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1
Mazaheri, Hoora, Hwai Chyuan Ong, Zeynab Amini, Haji Hassan Masjuki, M. Mofijur, Chia Hung Su, Irfan Anjum Badruddin e T. M. Yunus Khan. "An Overview of Biodiesel Production via Calcium Oxide Based Catalysts: Current State and Perspective". Energies 14, n. 13 (1 luglio 2021): 3950. http://dx.doi.org/10.3390/en14133950.
Testo completoAbstract (sommario):
Biodiesel is a clean, renewable, liquid fuel that can be used in existing diesel engines without modification as pure or blend. Transesterification (the primary process for biodiesel generation) via heterogeneous catalysis using low-cost waste feedstocks for catalyst synthesis improves the economics of biodiesel production. Heterogeneous catalysts are preferred for the industrial generation of biodiesel due to their robustness and low costs due to the easy separation and relatively higher reusability. Calcium oxides found in abundance in nature, e.g., in seashells and eggshells, are promising candidates for the synthesis of heterogeneous catalysts. However, process improvements are required to design productive calcium oxide-based catalysts at an industrial scale. The current work presents an overview of the biodiesel production advancements using calcium oxide-based catalysts (e.g., pure, supported, and mixed with metal oxides). The review discusses different factors involved in the synthesis of calcium oxide-based catalysts, and the effect of reaction parameters on the biodiesel yield of calcium oxide-based catalysis are studied. Further, the common reactor designs used for the heterogeneous catalysis using calcium oxide-based catalysts are explained. Moreover, the catalytic activity mechanism, challenges and prospects of the application of calcium oxide-based catalysts in biodiesel generation are discussed. The study of calcium oxide-based catalyst should continue to be evaluated for the potential of their application in the commercial sector as they remain the pivotal goal of these studies.
2
Stegner, Philipp C., Jonathan Eyselein, Gerd M. Ballmann, Jens Langer, Jochen Schmidt e Sjoerd Harder. "Calcium catalyzed enantioselective intramolecular alkene hydroamination with chiral C2-symmetric bis-amide ligands". Dalton Transactions 50, n. 9 (2021): 3178–85. http://dx.doi.org/10.1039/d1dt00173f.
Testo completoAbstract (sommario):
Enantioselective catalysis with calcium catalysts is challenging due to facile loss of the chiral spectator ligand. Herein a series of bis-amide calcium catalysts with chiral binaphtalene bridges is introduced.
3
Alsowayigh, Marwah M., Amal H. Alsehli, Fahad Alqahtani, Fahad Abdulaziz, Moncef Tounsi, Mazen Alshaaer e Abdulaziz Alanazi. "Investigation of Calcium Phosphate Catalysts in Sodium Borohydride Methanolysis for Improved Hydrogen Production". Catalysts 14, n. 8 (7 agosto 2024): 512. http://dx.doi.org/10.3390/catal14080512.
Testo completoAbstract (sommario):
In this study, calcium-rich resource minerals such as brushite, tricalcium phosphate (TCP), and hydroxyapatite were tested as catalysts for the methanolysis of alkaline solutions of NaBH4 to generate hydrogen H2. The synthesis of calcium phosphate compounds was characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The hydrogen generation rate with the TCP catalyst (15,214 mL min−1 g−1) was higher than with the hydroxyapatite catalyst (12,437 mL min−1 g−1) and brushite catalyst (6210 mL min−1 g−1) for the methanolysis of 250 mg NaBH4 at 298 K using 25 mg of catalyst. The impact of TCP weight on hydrogen generation was studied. The methanolysis reaction led to a higher hydrogen volume generation over time with an increase in the weight of the TCP catalyst at a temperature of 308 K. The calculated activation energy for NaBH4 hydrolysis with the TCP catalyst was 23.944 kJ mol−1, suggesting the high catalytic activity of TCP. The values of enthalpy (ΔH) and entropy (ΔS) were calculated, and the results showed that ΔH was 21.28 kJ mol−1 and ΔS was −93.096 J·mol−1. ΔH was positive, meaning that the reaction was endothermic, and the negative ΔS meant a decrease in the disorder of the methanolysis reaction. The stability of the catalysis was tested in successive methanolysis tests. The catalyst’s efficiency decreased to 89% after four cycles.
4
Díaz-Muñoz, L. L., H. E. Reynel-Ávila, D. I. Mendoza-Castillo, A. Bonilla-Petriciolet e J. Jáuregui-Rincón. "Preparation and Characterization of Alkaline and Acidic Heterogeneous Carbon-Based Catalysts and Their Application in Vegetable Oil Transesterification to Obtain Biodiesel". International Journal of Chemical Engineering 2022 (20 luglio 2022): 1–13. http://dx.doi.org/10.1155/2022/7056220.
Testo completoAbstract (sommario):
This paper reports the preparation, evaluation, and comparison of alkaline and acidic heterogeneous carbon-based catalysts in the transesterification of safflower oil with methanol to obtain biodiesel. These catalysts were obtained from the pyrolysis of flamboyant pods and their functionalization and activation with potassium hydroxide, citric acid, tartaric acid, sulfuric acid, and calcium nitrate. Different routes for the preparation of these catalysts were tested and analyzed where the FAME formation was the target variable to be improved. Results showed that the catalyst prepared with potassium hydroxide and calcium nitrate achieved the highest FAME formation (i.e., 95%) and outperformed the catalysts prepared with calcium nitrate and other acids even after four regeneration-reaction cycles. The best properties of an alkaline catalyst could be associated with its specific surface area and contents of potassium and calcium moieties, which were higher than those observed for acidic catalysts. Transesterification rates for biodiesel production were better estimated with the pseudo-order kinetic model, which ranged from 0.0004 to 0.038 L/mol⋅min for alkaline and acidic catalysts.
5
Istadi, Istadi, Udin Mabruro, Bintang Ayu Kalimantini, Luqman Buchori e Didi Dwi Anggoro. "Reusability and Stability Tests of Calcium Oxide Based Catalyst (K2O/CaO-ZnO) for Transesterification of Soybean Oil to Biodiesel". Bulletin of Chemical Reaction Engineering & Catalysis 11, n. 1 (10 marzo 2016): 34. http://dx.doi.org/10.9767/bcrec.11.1.413.34-39.
Testo completoAbstract (sommario):
<p>This paper was purposed for testing reusability and stability of calcium oxide-based catalyst (K<sub>2</sub>O/CaO-ZnO) over transesterification reaction of soybean oil with methanol to produce biodiesel. The K<sub>2</sub>O/CaO-ZnO catalyst was synthesized by co-precipitation method of calcium and zinc nitrates followed by impregnation of potassium nitrate. The fresh and used catalysts were tested after regeneration. The catalysts were characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and BET Surface Area in order to compare the catalyst structure between the fresh and used catalysts. The catalyst testing in transesterification proses was carried out at following operating conditions, i.e. catalyst weight of 6 wt.%, oil to methanol mole ratio of 1:15, and temperature of 60 oC. In addition, metal oxide leaching of K<sub>2</sub>O/CaO-ZnO catalyst during reaction was also tested. From the results, the catalysts exhibited high catalytic activity (80% fatty acid methyl ester (FAME) yield after three-cycles of usage) and acceptable reusability after regeneration. The catalyst also showed acceptable stability of catalytic activity, even after three-cycles of usage. Copyright © 2016 BCREC GROUP. All rights reserved</p><p><em>Received: 10<sup>th</sup> November 2015; Revised: 16<sup>th</sup> January 2016; Accepted: 16<sup>th</sup> January 2016</em></p><p><strong>How to Cite</strong>: Istadi, I., Mabruro, U., Kalimantini, B.A., Buchori, L., Anggoro, D.D. (2016). Reusability and Stability Tests of Calcium Oxide Based Catalyst (K<sub>2</sub>O/CaO-ZnO) for Transesterification of Soybean Oil to Biodiesel. <em>Bulletin of Chemical Reaction Engineering & Catalysis</em>, 11 (1): 34-39. (doi:10.9767/bcrec.11.1.413.34-39)</p><p><strong>Permalink/DOI</strong>: <a href="http://dx.doi.org/10.9767/bcrec.11.1.413.34-39">http://dx.doi.org/10.9767/bcrec.11.1.413.34-39</a></p><p> </p>
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Li, Changqing, Xinyue Cui, Aili Wang, Hengbo Yin, Yuting Li, Qiao Lin e Junjie Guo. "Direct Synthesis of Calcium Lactate through the Reaction of Glycerol with Calcium Hydroxide Catalyzed by Bimetallic AuCu/SiO2 Nanocatalysts". Catalysts 14, n. 5 (11 maggio 2024): 318. http://dx.doi.org/10.3390/catal14050318.
Testo completoAbstract (sommario):
Bimetallic AuCu/SiO2 nanosized catalysts were prepared using the wet chemical reduction technique. From among Au0.1–1.5Cu10/SiO2 catalysts, the Au0.5Cu10/SiO2 catalyst gave the highest yield of calcium lactate of 87% at a glycerol conversion of 96% when the reaction of glycerol with calcium hydroxide at a mole ratio of calcium hydroxide to glycerol of 0.8:1 was conducted under an anaerobic atmosphere at 200 °C for 2 h. The interactions between metallic Au0 and Cu0 nanoparticles facilitate calcium lactate formation. The simulation of glycerol consumption rate with an empirical power-function reaction kinetics equation yielded a reaction activation energy of 44.3 kJ∙mol−1, revealing that the catalytic reaction of glycerol with calcium hydroxide to calcium lactate can be conducted by overcoming a mild energy barrier. The synthesis of calcium lactate through the catalytic reaction of glycerol with calcium hydroxide on a bimetallic AuCu/SiO2 nanosized catalyst under a safe anaerobic atmosphere is an alternative to the conventional calcium lactate production technique through the reaction of expensive lactic acid with calcium hydroxide.
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Suprapto, Suprapto, Tikha Reskiani Fauziah, Meiske S. Sangi, Titie Prapti Oetami, Imroatul Qoniah e Didik Prasetyoko. "Calcium Oxide from Limestone as Solid Base Catalyst in Transesterification of Reutealis trisperma Oil". Indonesian Journal of Chemistry 16, n. 2 (13 marzo 2018): 208. http://dx.doi.org/10.22146/ijc.21165.
Testo completoAbstract (sommario):
CaO catalysts were synthesized from limestone by thermal decomposition and coprecipitation methods. The CaO and MgO reference catalysts were also synthesized for comparison. The catalysts were characterized by X-ray diffractometer (XRD) and the analysis result was refined by Rietica software. CaO catalyst obtained by coprecipitation method has higher purity of CaO and lower MgO content than those of calcined CaO. The catalysts were also characterized by Fourier Transform Infrared (FTIR) spectroscopy. FTIR spectra showed that the catalysts can be easily hydrated and carbonated in air. The catalytic activity of the catalyst was studied in transesterification reaction of Reutealis trisperma (Kemiri Sunan) oil with methanol. Transesterification reaction was carried out at oil to methanol molar ratio 1:1 and 1% of catalyst at 60 °C for 2 h. Catalytic activity of CaO catalyst obtained by coprecipitation was higher than calcined CaO. The methyl ester yield obtained from synthesized CaO, CaO from coprecipitation, calcined CaO, and synthesized MgO catalysts were 56.13; 37.74; 15.97; and 3.61%, respectively.
8
Garbarino, Gabriella, Federico Pugliese, Tullio Cavattoni, Guido Busca e Paola Costamagna. "A Study on CO2 Methanation and Steam Methane Reforming over Commercial Ni/Calcium Aluminate Catalysts". Energies 13, n. 11 (1 giugno 2020): 2792. http://dx.doi.org/10.3390/en13112792.
Testo completoAbstract (sommario):
Three Ni-based natural gas steam reforming catalysts, i.e., commercial JM25-4Q and JM57-4Q, and a laboratory-made catalyst (26% Ni on a 5% SiO2–95% Al2O3), are tested in a laboratory reactor, under carbon dioxide methanation and methane steam reforming operating conditions. The laboratory catalyst is more active in both CO2 methanation (equilibrium is reached at 623 K with 100% selectivity) and methane steam reforming (92% hydrogen yield at 890 K) than the two commercial catalysts, likely due to its higher nickel loading. In any case, commercial steam reforming catalysts also show interesting activity in CO2 methanation, reduced by K-doping. The interpretation of the experimental results is supported by a one-dimensional (1D) pseudo-homogeneous packed-bed reactor model, embedding the Xu and Froment local kinetics, with appropriate kinetic parameters for each catalyst. In particular, the H2O adsorption coefficient adopted for the commercial catalysts is about two orders of magnitude higher than for the laboratory-made catalyst, and this is in line with the expectations, considering that the commercial catalysts have Ca and K added, which may promote water adsorption.
9
Wang, Jian, e Yi Fan Zhang. "The Study of Divalent Metal Ion Catalysts on Phenol-Formaldehyde Resol Resins". Applied Mechanics and Materials 71-78 (luglio 2011): 818–21. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.818.
Testo completoAbstract (sommario):
The curing characteristic of phenol-formaldehyde resol resins catalyzed with magnesium hydroxide, calcium hydroxide and barium hydroxide was studied in this study.The effects of catalysts on chemical structure of phenol formaldehyde resin was investigated by fourier transform infrared.The results indicated that divalent metal ions catalysts played an important role influence both the cure rate and cure time.Phenol formaldehyde resin catalysed by diffierent catalysts showed diffierent addition of formaldehyde onto ortho positions of phenolic rings.The order of the divalent metal ions effectiveness studied in alkaline conditions is calcium hydroxide, barium hydroxide and magnesium hydroxide.
10
Lee, Sungho, Jeyoung Ha e Oi Lun Li. "Plasma Modification of Biomass-Based Starfish Catalysts for Efficient Biodiesel Synthesis". Nanomaterials 14, n. 15 (4 agosto 2024): 1313. http://dx.doi.org/10.3390/nano14151313.
Testo completoAbstract (sommario):
This study investigated biodiesel production via the transesterification of grapeseed oil with plasma-modified biomass-based catalysts originating from starfish. Dried starfish was first converted into magnesium and calcium oxide through heat treatment and then further modified by plasma engineering to improve the catalyst’s surface area and active sites via zinc addition. The Zn content was added via plasma engineering in the ratios of starfish (Mg0.1Ca0.9CO3): ZnO varying from 5:1, 10:1, to 20:1. The structure and morphology of the catalyst were confirmed through XRD, SEM, and XPS analysis. After the Zn addition and activation process, the surface area and the basicity of the synthesized catalysts were increased. The plasma-modified catalyst showed the highest basicity at the ratio of 10:1. Based on HPLC analyses, the optimized biodiesel yield in transesterification demonstrated 97.7% in fatty acid conversion, and its catalytic performance maintained 93.2% even after three repeated runs.
11
Balloi, Valentina, Manuel Antonio Diaz-Perez, Mayra Anabel Lara-Angulo, David Villalgordo-Hernández, Javier Narciso, Enrique V. Ramos-Fernandez e Juan Carlos Serrano-Ruiz. "Metal–Organic Frameworks as Formose Reaction Catalysts with Enhanced Selectivity". Molecules 28, n. 16 (17 agosto 2023): 6095. http://dx.doi.org/10.3390/molecules28166095.
Testo completoAbstract (sommario):
The formose reaction is an autocatalytic series of aldol condensations that allows one to obtain monosaccharides from formaldehyde. The formose reaction suffers from a lack of selectivity, which hinders practical applications at the industrial level. Over the years, many attempts have been made to overcome this selectivity issue, with modest results. Heterogeneous porous catalysts with acid–base properties, such as Metal–Organic Frameworks (MOFs), can offer advantages compared to homogeneous strong bases (e.g., calcium hydroxide) for increasing the selectivity of this important reaction. For the very first time, four different Zeolite Imidazolate Frameworks are presented in this work as catalysts for the formose reaction in liquid phase, and their catalytic performances were compared with those of the typical homogeneous catalyst (i.e., calcium hydroxide). The heterogeneous nature of the catalysis, the possible contribution of leached metal or linkers to the solution, and the stability of the materials were investigated. The porous structure of these solids and their mild basicity make them suitable for obtaining enhanced selectivity at 30% formaldehyde conversion. Most of the MOFs tested showed low structural stability under reaction conditions, thereby indicating the need to search for new MOF families with higher robustness. However, this important result opens the path for future research on porous heterogeneous basic catalysts for the formose reaction.
12
Brutovský, Milan, Daniela Kladeková, Katarína Reiffová e Adam Košturiak. "Vanadium-Phosphorus Catalysts Modified with Magnesium, Calcium and Barium". Collection of Czechoslovak Chemical Communications 62, n. 3 (1997): 392–96. http://dx.doi.org/10.1135/cccc19970392.
Testo completoAbstract (sommario):
Vanadium-phosphorus catalysts specially modified with promotors can ensure an efficient and selective oxidation of C4 hydrocarbons, even also that of butane to maleic anhydride. The catalysts with incorporated Mg, Ca or Ba ions provide a higher conversion of butane, yield of maleic anhydride, and selectivity for the latter compound than the unmodified catalyst. The conversion of butane and yield of maleic anhydride decrease with increasing basicity of the incorporated modifiers in the order: Mg, Ca, Ba, however, the selectivity of formation of maleic anhydride increases in the opposite order, which is interpreted by the idea that on the modified V-P catalysts the conversion of butane decreases faster than the yield of the anhydride with the natural basicity of the above-mentioned modifiers.
13
Kesic, Zeljka, Ivana Lukic, Miodrag Zdujic, Ljiljana Mojovic e Dejan Skala. "Calcium oxide based catalysts for biodiesel production: A review". Chemical Industry and Chemical Engineering Quarterly 22, n. 4 (2016): 391–408. http://dx.doi.org/10.2298/ciceq160203010k.
Testo completoAbstract (sommario):
Vegetable oils are mainly esters of fatty acids and glycerol, which can be converted to fatty acid methyl esters (FAME), also known as biodiesel, by the transesterification reaction with methanol. In order to attain environmental benignity, a large attention has been focused in the last decades on utilizing heterogeneous catalysts for biodiesel production instead the homogenously catalyzed transesterification of vegetable oil. The pure CaO or CaO mixed with some other metal oxide due to its low solubility in methanol, FAME and glycerol, low cost and availability is one of the most promising among the proposed heterogeneous catalysts. Solid catalysts which contain CaO usually fulfill a number of important requirements, such as high activity at mild temperature, marginal leaching of Ca cations, long life activity, reusability in transesterification of vegetable oil and easy recovery from the final products of transesterification (FAME and glycerol). This review is focused to the recent application of pure CaO or CaO in complex catalyst structure and their use as heterogeneous base catalysts for biodiesel synthesis and suitability for industrial application.
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Fayzullayev, N., K. Akmalaiuly e A. Karjavov. "CATALYTIC SYNTHESIS OF A LINE BY ACETYLENE HYDRATION". SERIES CHEMISTRY AND TECHNOLOGY 2, n. 440 (15 aprile 2020): 23–30. http://dx.doi.org/10.32014/2020.2518-1491.19.
Testo completoAbstract (sommario):
Acetone is a valuable chemical product. It can be obtained by oxidative dehydrogenation of isopropyl alcohol, oxidation of propylene, decomposition of acetic acid and ethyl alcohol, oxidation of cymene and others. Among the known processes for the production of acetone, the most promising is the synthesis by hydration of acetylene in the presence of catalysts. The advantage of this method is the possibility of carrying out the process in existing plants for the production of acetic aldehyde. On the other hand, the process of simultaneously producing acetaldehyde and acetone under the influence of multifunctional catalysts and carrying out the process using flexible technology is promising. The vapor-phase hydration of acetylene with the formation of acetone on polyfunctional catalysts was studied. Process parameters are found that provide acetone with high selectivity and acetylene conversion. At present, acetic aldehyde is mainly obtained by two methods - hydration of acetylene and oxidation of ethylene. The process of hydration of acetylene to acetic aldehyde in the presence of catalysts has been studied quite well. Numerous catalysts have been proposed for this process. Among the known catalysts for hydration of acetylene to acetic aldehyde, the most active was the cadmium calcium phosphate catalyst (CCF), which is recommended for industrial use. However, cadmium calcium phosphate catalyst is not without drawbacks. The average yield of acetaldehyde in one pass of acetylene does not exceed 7.0%. The CCF catalyst is very sensitive to temperature changes, its service life before regeneration does not exceed 72-76 hours. Keywords: acetone, propylene, hydration process, catalyst, crosslinking, multifunctional properties.
15
Huang, Da Ming, Wei Wei Jiang, Lin Lin, Saritporn Vittayapadung, Zhi Hong Xiao, Ai Hua Zhang e Chang Zhu Li. "Study on the Catalyst Performance on Cornus wisoniana Oil Catalytic Cracking Prepared Biological Fuel Oil". Applied Mechanics and Materials 477-478 (dicembre 2013): 1457–63. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.1457.
Testo completoAbstract (sommario):
In our Research, we Used Cornus Wisoniana oil as Feedstock and the High Temperature Pyrolysis Kettle as the Reactor. Examine the Performance of Lanthanum Oxide, Zirconium Sulfate, Calcium Oxide and KF Loaded Catalyst on Cornus Wisoniana oil Catalytic Cracking Reaction. and through the SEM, XRD and FT-IR, Optimal Catalysts were Used to Characterize the Structure. the Results Showed that among KF Modified Catalyst KF Supported on Cao Produced Highest Yield of Bio-Fuel Oil from Cornus Wisoniana oil. when the Dosage of Catalyst Reached 1%, KF Impregnation Ratio of 40%, and Catalyst Calcination for 4h at 600°C, it can be Obtained Highest Yield of Bio-Fuel Oil about 82.7% and Reaction Rate up to 94.1. in Addition to the KF/MgO Having Low Yield about 60.6%, Catalytic Activity of other Four KF Catalysts were Higher than that of Lanthanum Oxide, Zirconium Sulfate and Calcium Oxide. the Catalytic Efficiency of Lanthanum Oxide and Zirconium Sulfate Appeared Similarity and are all Low. the Catalytic Activity of Calcium Oxide is Slightly Higher than the Lanthanum Oxide and Zirconium Sulfate, but Lower than that of KF/CaO Catalyst.
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Buasri, Achanai, Teera Sriboonraung, Kittika Ruangnam, Pattarapon Imsombati e Vorrada Loryuenyong. "Utilization of Waste Enamel Venus Shell as Friendly Environmental Catalyst for Synthesis of Biodiesel". Key Engineering Materials 659 (agosto 2015): 237–41. http://dx.doi.org/10.4028/www.scientific.net/kem.659.237.
Testo completoAbstract (sommario):
Calcium oxide (CaO) is one of the most promising heterogeneous alkali catalysts since it is cheap, abundantly available in nature, and some of the sources of this compound are renewable (waste material consisting of calcium carbonate (CaCO3)). In this study, the waste enamel venus shell was used as the raw material for CaO catalyst. The calcination of bio-waste was conducted at 900 °C for 2 h. The raw material and the resulting CaO catalyst were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and the Brunauer-Emmett-Teller (BET) method. The effects of reaction variables such as reaction time, microwave power, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated by gas chromatograph-mass spectrometry (GC-MS). From the experimental results, it was found that the CaO catalysts derived from waste material showed good catalytic activity (the conversion of oil of nearly 93%, a very similar catalytic activity with laboratory CaO) and had high potential to be used as biodiesel production catalysts in transesterification of Jatropha Curcas oil with methanol.
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Koesnarpadi, Soerja, Teguh Wirawan, Mukhamad Nurhadi, Wirhanuddin Wirhanuddin, Yuniar Ponco Prananto, Nazarudin Nazarudin, Volkan Degirmenci, Sin Yuan Lai e Hadi Nur. "Oxidation of Styrene to Benzaldehyde Using Environmentally Friendly Calcium Sulfate Hemihydrate-Supported Titania Catalysts". Bulletin of Chemical Reaction Engineering & Catalysis 19, n. 4 (25 novembre 2024): 622–34. http://dx.doi.org/10.9767/bcrec.20224.
Testo completoAbstract (sommario):
This paper presents the synthesis and characterization of calcium sulfate hemihydrate (CSH)-supported titania (TiO2) catalysts and their application in the environmentally friendly oxidation of styrene to benzaldehyde using hydrogen peroxide (H2O2) as the oxidant. The study explores the catalyst's structure-activity relationship, emphasizing the importance of mesoporous materials for enhanced catalytic performance. The CSH-Titania catalysts were synthesized using fish bone-derived CSH as a support, which aligns with green chemistry principles. Characterization techniques such as Fourier Transform Infra Red (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis confirmed the successful impregnation of titania and its catalytic efficiency. The catalysts exhibited high selectivity for benzaldehyde, achieving up to 49.45% conversion of styrene, with benzaldehyde as being the main product. The research highlights that the catalyst’s performance decreased after calcination due to a reduced surface area and pore volume, yet it maintained recyclability across three cycles with minimal lose in selectivity loss. Overall, this study introduces a cost-effective and sustainable approach to styrene oxidation, demonstrating the potential for industrial application in producing high-value chemicals with minimal environmental impact. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
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Al-asadi, Mohammed, e Norbert Miskolczi. "High Temperature Pyrolysis of Municipal Plastic Waste Using Me/Ni/ZSM-5 Catalysts: The Effect of Metal/Nickel Ratio". Energies 13, n. 5 (10 marzo 2020): 1284. http://dx.doi.org/10.3390/en13051284.
Testo completoAbstract (sommario):
This work is dedicated to the high temperature pyrolysis of municipal plastic waste using Me/Ni/ZSM-5 catalysts. Catalysts were synthetized by wet impregnation. In addition to nickel, synthetic zeolite catalysts contain calcium, ceria, lanthanum, magnesia or manganese. Catalysts were prepared and tested using 0.1, 0.5 and 2.0 Me/Ni ratios. Catalyst morphology was investigated by SEM and surface analysis. Higher concentrations of second metals can block catalyst pore channels due to the more coke formation, which leads to smaller surface area. Furthermore, the chemicals used for the impregnation were among the catalyst grains, especially in case of 2.0 Me/Ni ratios. For pyrolysis, a horizontal tubular furnace reactor was used at 700 °C. The highest hydrogen and syngas yields were observed using ceria- and lanthanum-covered catalysts. The maximum production of syngas and hydrogen (69.8 and 49.2 mmol/g raw material) was found in the presence of Ce/Ni/ZSM-5 catalyst with a 0.5 Me/Ni ratio.
19
Wang, Bo, Xueyong Ding, Xiaofei Zhang, Tianhua Ju e Shigang Li. "Effect of catalyst on tail gas during reduction of vanadium-titanium magnetite carbon-containing pellet". E3S Web of Conferences 267 (2021): 02046. http://dx.doi.org/10.1051/e3sconf/202126702046.
Testo completoAbstract (sommario):
Catalyst can enhance the reduction effect and promote the reduction of vanadium titanomagnetite. In this paper, the carbon-containing pellets of vanadium titanomagnetite were prepared by using highly volatile coal as the reducing agent under the background of a novel process of pre-reduction in the rotary kiln. The effects of CaO, CaCO3, B2O3 and borax (Na2B4O7·10H2O) on the tail gas characteristics of carbon-containing pellets in the prereduction process were studied by using a simulated rotary kiln and flue gas analyzer. The results showed that the enhanced reduction effect of boron catalysts was slightly stronger than that of calcium catalysts, among which CaO catalyzed the least and borax the best. With the increase of metallization rate, the CO utilization in the tail gas is generally reduced, while when using CaCO3 as the catalyst, the CO utilization is significantly increased. Due to different reduction mechanism, the boron catalysts have little effect on the tail gas, and the calcium catalysts have a great effect on the tail gas. Based on the experimental results and the characteristics of the tail gas from the reduction process, we put forward the idea of using CaCO3 as the best catalyst and using CaO to absorb CO2 in the tail gas to form CaCO3.
20
Syuhada, Ain, Mariam Ameen, Farooq Sher, Mohammad Tazli Azizan, Aqsha Aqsha, Mohd Hizami Mohd Yusoff e Muhamad Syafiq Hazwan Ruslan. "Effect of Calcium Doping Using Aqueous Phase Reforming of Glycerol over Sonochemically Synthesized Nickel-Based Supported ZrO2 Catalyst". Catalysts 11, n. 8 (16 agosto 2021): 977. http://dx.doi.org/10.3390/catal11080977.
Testo completoAbstract (sommario):
The aqueous phase reforming (APR) of glycerol was studied using sonochemically synthesized 10%Ni-x%Ca/ZrO2 catalysts (where x = 0, 0.5, 3, and 5) for the production of value-added liquid products. The APR reaction was performed in a batch reactor under the following conditions: 20 bar, 230 °C 450 rpm, and 1 h of reaction time. The synthesized catalysts were characterized using XRD, FESEM, BET, and H2-TPR to observe the effect of Ca doping on the physio-chemical properties of the catalysts. The results revealed that, at higher Ca loading, the catalysts experienced serious particles’ agglomeration, which resulted in a larger particles’ size, smaller surface area, and smaller pore volume owing to uneven distribution of the particles. The characterization results of the catalysts confirmed that the Us catalysts have a slightly higher surface area, pore volume, and pore size, as well as highly reducible and fine crystalline structure, compared with WI catalysts. The catalytic performance of the catalysts shows that 1,3-propanediol (1,3-PDO) and 1,2-propanediol (1,2-PDO) were the two main liquid products produced from this reaction. The highest selectivity of 1,3-PDO (23.84%) was obtained over the 10%Ni/ZrO2 catalyst, while the highest selectivity of 1,2-PDO (25.87%) was obtained over the 10%Ni-5%Ca/ZrO2 catalyst.
21
Gaide, Ieva, Violeta Makareviciene, Egle Sendzikiene e Kiril Kazancev. "Natural Rocks–Heterogeneous Catalysts for Oil Transesterification in Biodiesel Synthesis". Catalysts 11, n. 3 (16 marzo 2021): 384. http://dx.doi.org/10.3390/catal11030384.
Testo completoAbstract (sommario):
Some of the more recent methods to produce biodiesel are based on heterogeneous catalysis, which has the advantage of easy separation of catalyst from the final product. In this paper, the heterogeneous transesterification of rapeseed oil with methanol is studied. The aim of this work was to investigate the possibilities of using natural catalysts in biodiesel synthesis and to determine the optimal conditions for this process. After the evaluation of catalytic effectiveness of rocks containing calcium and magnesium carbonates, it was determined that dolomite is the most effective catalyst in heterogeneous biodiesel synthesis. The optimal conditions of dolomite preparation are the following: heating at 850 °C for 5 h. The rapeseed oil transesterification was optimized by the application response surface methodology. Optimal conditions for the production of rapeseed methyl esters using dolomite as catalyst are the following: molar ratio of methanol to rapeseed oil of 11.94:1, reaction temperature of 64 °C, dolomite content of 6 wt%, reaction time of 5 h.
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Buasri, Achanai, Nattawut Chaiyut, Vorrada Loryuenyong, Phatsakon Worawanitchaphong e Sarinthip Trongyong. "Calcium Oxide Derived from Waste Shells of Mussel, Cockle, and Scallop as the Heterogeneous Catalyst for Biodiesel Production". Scientific World Journal 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/460923.
Testo completoAbstract (sommario):
The waste shell was utilized as a bioresource of calcium oxide (CaO) in catalyzing a transesterification to produce biodiesel (methyl ester). The economic and environmen-friendly catalysts were prepared by a calcination method at 700–1,000°C for 4 h. The heterogeneous catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET) method. The effects of reaction variables such as reaction time, reaction temperature, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the CaO catalysts derived from waste shell showed good reusability and had high potential to be used as biodiesel production catalysts in transesterification of palm oil with methanol.
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Dang, Kavisha, Navneet Kumar, Vimal Chandra Srivastava, Jinsub Park e Mu Naushad. "Efficient Propylene Carbonate Synthesis from Urea and Propylene Glycol over Calcium Oxide–Magnesium Oxide Catalysts". Materials 16, n. 2 (11 gennaio 2023): 735. http://dx.doi.org/10.3390/ma16020735.
Testo completoAbstract (sommario):
A series of calcium oxide–magnesium oxide (CaO–MgO) catalysts were prepared under the effects of different precipitating agents and using varied Mg/Ca ratios. The physiochemical characteristics of the prepared catalysts were analyzed using XRD, FE-SEM, BET, FTIR, and TG/DTA techniques. Quantification of basic active sites present on the surface of the CaO–MgO catalysts was carried out using the Hammett indicator method. The as-prepared mixed oxide samples were tested for propylene carbonate (PC) synthesis through the alcoholysis of urea with propylene glycol (PG). The effects of the catalyst composition, catalyst dose, reaction temperature, and contact time on the PC yield and selectivity were investigated. The maximum PC yield of 96%, with high PC selectivity of 99% and a urea conversion rate of 96%, was attained at 160 °C using CaO–MgO catalysts prepared using a Mg/Ca ratio of 1 and Na2CO3 as a precipitating agent. The best-performing catalysts also exhibited good reusability without any significant loss in PC selectivity. It is expected that the present study will provide useful information on the suitability of different precipitating agents with respect to the catalytic properties of the oxides of Ca and Mg and their application in the synthesis of organic carbonates.
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Guo, Yangyang, Xiaofei Xu, Hong Gao, Yang Zheng, Lei Luo e Tingyu Zhu. "Ca-Poisoning Effect on V2O5-WO3/TiO2 and V2O5-WO3-CeO2/TiO2 Catalysts with Different Vanadium Loading". Catalysts 11, n. 4 (30 marzo 2021): 445. http://dx.doi.org/10.3390/catal11040445.
Testo completoAbstract (sommario):
Ca poisoning behavior is inevitable for high-calcium content flue gas, so V2O5-WO3/TiO2 (VWT) and V2O5-WO3-CeO2/TiO2 (VWCeT) catalysts with different vanadium content have been prepared and the Ca-doped catalysts are compared in this manuscript. The result shows Ce addition can both promote the NO conversion and the alkali resistance. Lower Ca addition for 0.1VWCeT catalyst promotes its oxidability and Ce modification is more suitable for low vanadium catalysts. The total acidity and the reducibility of catalysts decline after Ca doping, and the reducibility of the active species on catalysts has been strengthened by Ce addition. CeO2 based catalysts with lower Ca loading struggle to resist sulfur poisoning, while higher Ca loading favors SO2 adsorption and also physically reduces the cerium acidification process. In the presence of SO2, additional Brønsted acid sites are formed in Ca rich catalyst. The dynamic NH3 adsorption has been investigated, shows that Ca doping content on catalyst is critical for SCR reaction, and the catalyst is more susceptible to SO2 initially in alkali flue gas during the actual application, but the sulfur resistance may increase with the alkali-poisoning effect aggravated by Ca doping.
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Hindryawati, Noor, Daniel Daniel, Erwin Erwin e Gaanty Pragas Maniam. "PREPARATION OF SPENT BLEACHING EARTH-SUPPORTED CALCIUM FROM LIMESTONE AS CATALYST IN TRANSESTERIFICATION OF WASTE FRYING OIL". Jurnal Bahan Alam Terbarukan 6, n. 1 (27 maggio 2017): 68–75. http://dx.doi.org/10.15294/jbat.v6i1.9860.
Testo completoAbstract (sommario):
An investigation was conducted on palm oil refinery waste-spent bleaching earth (POR-SBE), POR-SBE supported by calcium as catalysts for methyl esters production through transesterification process using waste frying oil. The catalysts showed longer lasting activity than the traditional alkali catalysts. The optimum conditions for the process were: Ca-POR-SBE catalyst amount 7 %; methanol to oil molar ratio 12:1; and a reaction duration is 4 h. The process was able to transesterify oil to methyl esters at 96.8 % conversion at 65 C. The catalysts were easily separated from the reaction mixture and the final product met selected biodiesel fuel properties in accordance with European Standard EN 14214.
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Makepeace, Joshua W., Hazel M. A. Hunter, Thomas J. Wood, Ronald I. Smith, Claire A. Murray e William I. F. David. "Ammonia decomposition catalysis using lithium–calcium imide". Faraday Discussions 188 (2016): 525–44. http://dx.doi.org/10.1039/c5fd00179j.
Testo completoAbstract (sommario):
Lithium–calcium imide is explored as a catalyst for the decomposition of ammonia. It shows the highest ammonia decomposition activity yet reported for a pure light metal amide or imide, comparable to lithium imide–amide at high temperature, with superior conversion observed at lower temperatures. Importantly, the post-reaction mass recovery of lithium–calcium imide is almost complete, indicating that it may be easier to contain than the other amide–imide catalysts reported to date. The basis of this improved recovery is that the catalyst is, at least partially, solid across the temperature range studied under ammonia flow. However, lithium–calcium imide itself is only stable at low and high temperatures under ammonia, with in situ powder diffraction showing the decomposition of the catalyst to lithium amide–imide and calcium imide at intermediate temperatures of 200–460 °C.
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REDDY, E. LINGA, A. PRABHAKARN, J. KARUPPIAH, N. RAMESHBABU e CH SUBRAHMANYAM. "GOLD SUPPORTED CALCIUM DEFICIENT HYDROXYAPATITE FOR ROOM TEMPERATURE CO OXIDATION". International Journal of Nanoscience 11, n. 03 (giugno 2012): 1240004. http://dx.doi.org/10.1142/s0219581x12400042.
Testo completoAbstract (sommario):
Gold supported hydroxyapatite (HA) and calcium deficient hydroxyapatite (CDHA) was studied for the room temperature CO oxidation. Nanostructured gold catalyst has been prepared by deposition precipitation method, whereas HA was synthesized by microwave synthesis. Inorder to understand the influence of surface properties of HA, support HA was synthesized with different Ca/P ratios (1.67, 1.62, 1.57, 1.534 and 1.5). The gold supported catalysts were characterized by XRD, BET, ICP-OES and TEM. Typical results indicate that gold supported 1.57 HA shows higher activity compared to other HA catalysts (1.67, 1.62, 1.534 and 1.5) which may be due to the presence of optimum number of acidic and basic sites.
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Çakırca, Emine E., Gizem N Tekin, Oğuzhan İlgen e Ayşe N Akın. "Catalytic activity of CaO-based catalyst in transesterification of microalgae oil with methanol". Energy & Environment 30, n. 1 (17 luglio 2018): 176–87. http://dx.doi.org/10.1177/0958305x18787317.
Testo completoAbstract (sommario):
In this work, activities of modified dolomite catalysts using calcium acetate in the heterogeneously catalyzed transesterification of microalgae oil with methanol were investigated. Modified catalysts were prepared via wet impregnation method and calcined 850°C for 2 h. Reaction conditions were examined as the catalyst type, amount of catalyst, methanol/microalgae oil molar ratio, and reusability of the catalyst using the dolomite and modified dolomite catalysts. When investigated reusability of the modified dolomite catalyst in the transesterification of microalgae oil with methanol, catalyst was reused three times with a small loss of activity. After fourth run, reused catalyst was calcined again and got similar activity to the first run. The highest fatty acid methyl esters (FAME) yield of 90% was obtained when the reaction was performed with methanol/microalgae oil molar ratio of 6:1, catalyst amount of 3%, and reaction temperature at 65°C for 3 h by using the 30% CaO/dolomite catalyst.
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Zheng, Yifan, Lin Gu, Yining Li, Jamal Ftouni e Abhishek Dutta Chowdhury. "Revisiting the Semi-Hydrogenation of Phenylacetylene to Styrene over Palladium-Lead Alloyed Catalysts on Precipitated Calcium Carbonate Supports". Catalysts 13, n. 1 (27 dicembre 2022): 50. http://dx.doi.org/10.3390/catal13010050.
Testo completoAbstract (sommario):
The quest for improved heterogeneous catalysts often leads to sophisticated solutions, which are expensive and tricky to scale up industrially. Herein, the effort to upgrade the existing inorganic nonmetallic materials has seldom been prioritized by the catalysis community, which could deliver cost-effective solutions to upgrade the industrial catalysts catalog. With this philosophy in mind, we demonstrate in this work that alloyed palladium-lead (Pd-Pb) deposited on novel precipitated calcium carbonate (PCC) supports could be considered an upgraded version of the industrial Lindlar catalyst for the semi-hydrogenation of phenylacetylene to styrene. By utilizing PCC supports of variable surface areas (up to 60 m2/g) and alloyed Pd-Pb loading, supported by material characterization tools, we showcase that achieving the “active-site isolation” feature could be the most pivotal criterion to maximize semi-hydrogenated alkenes selectivity at the expense of prohibiting the complete hydrogenation to alkanes. The calcite phase of our PCC supports governs the ultimate catalysis, via complexation with uniformly distributed alloyed Pb, which may facilitate the desired “active-site isolation” feature to boost the selectivity to the preferential product. Through this work, we also advocate increasing research efforts on mineral-based inorganic nonmetallic materials to deliver novel and improved cost-effective catalytic systems.
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Li, Suan, Zhenguang Sun, Qi Liu, Hang Ye e Kunpeng Wang. "Self-catalysed hydrogenation of heavy oil and coal mixtures". Polish Journal of Chemical Technology 25, n. 2 (1 giugno 2023): 8–14. http://dx.doi.org/10.2478/pjct-2023-0011.
Testo completoAbstract (sommario):
Abstract Coal liquefaction and heavy oil processing have become the urgent need for national energy strategic technology reserves in China. However, the inactivation of solid catalysts in these processes is an inevitable problem. Therefore, a self-catalysed method was proposed. The properties of raw oil could be changed by adding a modifier, as it has the function of self-catalysis, and the additional catalyst is no longer needed. The effect of 200 ppm modifier on the hydrogenation of heavy oil and 500 ppm on the hydrogenation of coal and oil were investigated. The results showed that modifiers could be miscible with heavy oil at 50~100 °C and could change the properties of oil. When the temperature exceeded 250 °C, the sulfur element in the heavy oil combined with the metal element brought in by the modifier to form a particle with the size of 2–8 nm, which could interact with the hydrogen molecule to activate the hydrogen molecule. Activated hydrogen atoms further formed the complexes with nickel, vanadium, calcium, iron, and other elements in heavy oil to achieve the purpose of purifying and lightening the oil phase. Therefore, the self-catalysed method could be widely used in oil refining and would greatly promote the development of the oil refining and catalysis industry.
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Turabjanov, Sadritdin Makhamatdinovich, Bakhytzhan Shilmirzaevich Kedelbaev, Gaffor Rakhmonberdiev, Komila Sadriddin kizi Ibragimova e Khasan Irgashevich Kadirov. "DEVELOPMENT AND INVESTIGATION OF PROPERTIES OF MIXED CATALYSTS FOR VAPOR-PHASE HYDRATION OF ACETYLENE". Chronos 7, n. 11(73) (13 dicembre 2022): 155–58. http://dx.doi.org/10.52013/2658-7556-73-11-44.
Testo completoAbstract (sommario):
In order to develop new catalysts for the synthesis of acetaldehyde by vapor-phase hydration of acetylene, new mono- and bifunctional catalysts based on cadmium, zinc, chromium, and iron compounds on supports were developed and their most important textural characteristics were studied. It was shown that zinc oxide and cadmium fluoride are bifunctional catalysts, in the presence of which acetaldehyde was synthesized with a yield of 69.0 — 70.0%. It has been established that the stability of their operation before regeneration exceeds more than 100 hours, i.e. 1.3 times more than industrial cadmium-calcium phosphate catalyst.
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Begouin, Jeanne-Marie, e Meike Niggemann. "Calcium-Based Lewis Acid Catalysts". Chemistry - A European Journal 19, n. 25 (24 maggio 2013): 8030–41. http://dx.doi.org/10.1002/chem.201203496.
Testo completo
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Andiena, Resty Zama, Karna Wijaya e Akhmad Syoufian. "Nanocatalysts of Sulfated Zirconia and Calcium Oxide/Zirconia for Microwave-Assisted Biodiesel Synthesis from Castor Oil". Materials Science Forum 1067 (10 agosto 2022): 167–76. http://dx.doi.org/10.4028/p-4320g2.
Testo completoAbstract (sommario):
Nanocatalysts of sulfated zirconia (SZ) and CaO/zirconia for microwave assisted-biodiesel synthesis from castor oil have been successfully prepared. The aim of the research was to determine the effectiveness and the selectivity of catalysts in biodiesel production. The sulfated zirconia catalyst was prepared by the wet impregnation method while the calcium oxide/zirconia catalyst was prepared through the wet impregnation by microwave-assisted method. The catalysts were used for the esterification and transesterification reaction with the highest acidity and the basicity value of 7.16 mmol NH3 g-1, 87.76 mmol HCl g-1, respectively. The acidity and basicity of the catalysts are directly related to the catalyst active site in the esterification and transesterification process. The results showed that catalyst 0.5 M SZ 500 and 1: 0.2 CaO/ZrO2 800 had excellent stability that can be seen from their high crystallinity and large surface area. The biodiesel products characterized by 1H-NMR, GC-MS and Bomb calorimeter also showed excellent results. After purification, 1H-NMR result shows the conversion of castor oil into methyl ester is close to 100%. This was supported by GC-MS where the highest area of methyl ester is 93.91% of methyl ricinoleate.
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Ogunkunle, Oyetola, e Opeyeolu Timothy Laseinde. "Development of heterogeneous catalyst from assorted periwinkle snail shells for sustainable biodiesel synthesis". E3S Web of Conferences 430 (2023): 01230. http://dx.doi.org/10.1051/e3sconf/202343001230.
Testo completoAbstract (sommario):
Owing to the environmental friendliness of biodiesel compared to fossil fuels, its application in internal combustion engines has gained wide recognition. The biodiesel industry requires effective heterogeneous catalysts developed from agricultural biomass/residues due to their overall cost-effectiveness, recoverability, and reusability. Scientific reports on developing active heterogeneous catalysts from periwinkle snail shells for application in transesterification reactions are limited, as there is no evidence of stability test results for the catalyst’s structural and elemental composition analysis. Also, there is a deficit of information on the catalytic effect on biodiesel yields. This research developed a heterogeneous catalyst derived from periwinkle snail shells (PSS) for biodiesel production. Pulverized PSS were sieved through several apertures to separate the samples into different particle sizes, viz. 250 mm, 500mm, and 1000 mm. The samples were calcined in an electric furnace at 500 oC for 3 and 5 hrs. The calcined catalyst samples were characterized using XRD, SEM, and EDS. Purified WCO was transesterified using the CPSS with the highest metallic oxides percentage under different experimental levels. All the CPSS samples exhibited a change in colour and weight loss after the calcination period. XRD observations revealed that calcium oxide (CaO) is the principal constituent of the calcined PSS (CPSS). The results showed that the highest (93%) traces of CaO was found in PSS 500 mm size calcined at 500 oC for 5 hrs. EDS results showed that the same sample had the highest calcium (Ca) composition with a weight percent of 57.38%. The highest biodiesel yield of 94.6% was obtained at optimum conditions of 70 oC reaction temperature, 9:1 molar ratio, 60 minutes reaction period, and catalyst content of 3 wt%. It was observed that biodiesel yields decreased when the catalyst concentration increased beyond 3wt%. Compared to the same amount of homogeneous catalyst, KOH, an average biodiesel yield of 90% was recorded from the same transesterification reaction conditions. The development of heterogeneous catalysts from PSS was established as a cost-effective means of catalyzing transesterification reactions and obtaining high biodiesel yields from WCO with the prospects of possible catalyst recovery and reuse.
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Zotov, Yu L., D. M. Zapravdina, E. V. Shishkin e Yu V. Popov. "Study of calcium-containing compounds as catalysts for the esterification of glycerol with higher carboxylic acids". Fine Chemical Technologies 18, n. 3 (2 agosto 2023): 175–86. http://dx.doi.org/10.32362/2410-6593-2023-18-3-175-186.
Testo completoAbstract (sommario):
Objectives. To investigate the catalytic activity of calcium-containing basic catalysts for the esterification of glycerol with higher carboxylic acids in order to develop a low-waste technology for the production of multifunctional additives, as well as to assess the possibility of using the reaction products for the processing of polyvinyl chloride.Methods. The consumption of oleic acid during synthesis was monitored using a titrimetric method of analysis with visual indication. The structure of the synthesized calcium-containing catalysts was confirmed by infrared spectroscopy; elemental analysis was additionally performed for calcium glyceroxide. Quantitative and qualitative analyses of the resulting mixtures of oleic acid glycerides were carried out using chromato-mass spectrometry. A sample of a multifunctional additive was tested in a model formulation of a medical plastic compound based on polyvinyl chloride.Results. It is shown that the catalytic activity of calcium derivatives in the reaction of esterification of glycerol with higher carboxylic acids increases in the series СаО < Са(ОН)2 < Ca(C17H33COO)2 < Ca(C2H5O)2 < Ca(C4H9O)2 < Ca(C3H7O3)2, while the use of calcium glyceroxide as a catalyst in an amount from 1 to 6 mol % increases the conversion of carboxylic acid from 58 to 86% in 10 h of synthesis. However, varying the amount of calcium glyceroxide from 1.5 to 6 mol % results in no observed changes in the conversion of carboxylic acid. The multifunctional additive obtained by selecting calcium glyceroxide as a catalyst has a thermally stabilizing and plasticizing effect on the polymer composition. The introduction of the developed additive into the formulation of a polyvinyl chloride composition for medical purposes reduces the processing torque and time to reach the dry point. By combining these factors, energy costs during production were reduced by more than 11% compared to the control composition.Conclusions. It is established that calcium alcoholates catalyze the reaction of esterification of glycerol with oleic (or higher) acid to increase the conversion of the initial substances and selectivity for the formation of monoglycerides as compared with calcium oxide, hydroxide, and oleate. By optimizing the ratio of glycerol : oleic acid : calcium glyceroxide at 1 : 1 : 0.015, the maximum conversion of oleic acid of up to 86% in 10 h was obtained via synthesis. The proposed method for esterification of glycerol with higher carboxylic acids in the presence of a calcium-containing catalyst avoids the stage of purification from the catalyst to obtain a composition with multifunctional additive properties for the processing of polyvinyl chloride.
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Sing Chong, Ngee, Francis Uchenna Okejiri, Saidi Abdulramoni, Shruthi Perna e Beng Guat Ooi. "Evaluation of Shell-Derived Calcium Oxide Catalysts for the Production of Biodiesel Esters from Cooking Oils". Academic Journal of Chemistry, n. 61 (29 marzo 2021): 20–27. http://dx.doi.org/10.32861/ajc.61.20.27.
Testo completoAbstract (sommario):
Due to the high cost of feedstock and catalyst in biodiesel production, the viability of the biodiesel industry has been dependent on government subsidies or tax incentives. In order to reduce the cost of production, food wastes including eggshells and oyster shells have been used to prepare calcium oxide (CaO) catalysts for the transesterification reaction of biodiesel synthesis. The shells were calcined at 1000 °C for 4 hours to obtain CaO powders which were investigated as catalysts for the transesterification of waste cooking oil. The catalysts were characterized by Fourier Transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and X-ray fluorescence (XRF) spectroscopy. Reaction parameters such as methanol-to-oil molar ratio, CaO catalyst concentration, and reaction time were evaluated and optimized for the percentage conversion of cooking oil to biodiesel esters. The oyster-based CaO showed better catalytic activity when compared to the eggshell-based CaO under the same set of reaction conditions.
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Weissenberger, Tobias, Ralf Zapf, Helmut Pennemann e Gunther Kolb. "Catalyst Coatings for Ammonia Decomposition in Microchannels at High Temperature and Elevated Pressure for Use in Decentralized and Mobile Hydrogen Generation". Catalysts 14, n. 2 (26 gennaio 2024): 104. http://dx.doi.org/10.3390/catal14020104.
Testo completoAbstract (sommario):
We report an investigation of catalyst performance for the decomposition of ammonia under industrially relevant conditions (high temperatures of up to 800 °C and an elevated pressure of 5 bar) with further emphasis on their stability at high reaction temperatures. The catalysts were applied and tested as coatings in 500 µm wide channels of microreactors. Nickel-based catalysts were studied and compared to a ruthenium-based catalyst supported on SiO2. The effect of the support on the catalytic performance was investigated, and CeO2-supported nickel catalysts were found to exhibit the highest activity. Promoters were applied to increase the NH3 decomposition activity of the Ni/CeO2 catalysts. The addition of cesium led to a slight reduction in activity, while lanthanum, calcium, and barium doping resulted in increased activity. In particular, the barium-doped Ni/CeO2 catalyst showed very high ammonia conversion and closed the activity gap with respect to ruthenium catalysts at reactor temperatures of 650 °C and higher. The hydrogen production rates achieved in this work were compared to values in the literature and were shown to exceed values found earlier for both nickel- and ruthenium-based catalysts. Furthermore, the ruthenium-based catalysts under investigation were rapidly deactivated at 700 °C, while the nickel-based catalysts did not show deactivation after 220 h on time on stream at 700 °C.
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Ali, Nur Afiqah, e Nozieana Khairuddin. "Biodiesel Production from Waste Cooking Oil using Heterogeneous CaO/Zn Catalyst: Yield and Reusability Performance". Chiang Mai Journal of Science 50, n. 6 (30 novembre 2023): 1–15. http://dx.doi.org/10.12982/cmjs.2023.070.
Testo completoAbstract (sommario):
Biodiesel is a r enewable, biodegradable, and non-toxic fuel derived from vegetable oils, animal fats, or recycled cooking oils. Biodiesel can be used as a direct replacement for diesel in diesel engines with minimal or no modification, and it has several advantages over conventional diesel. Eggshells, on the other hand, are composed mainly of calcium carbonate (CaCO3), a valuable resource for various industrial and agricultural applications. Improper disposal of eggshells can cause environmental pollution and discarding of eggshells in landfills takes up valuable space and emits potent greenhouse gases such as methane. The current study focuses on biodiesel production from waste cooking oil (WCO) using heterogeneous catalysts from eggshells impregnated with Zinc (Zn) metal. The transesterification process can produce biodiesel using WCO in the presence of a catalyst. The free fatty acid (FFA) of WCO is 0.45 mg KOH/g lower, enabling the transesterification process. The CaCO3 present in the eggshell will be converted into calcium oxide (CaO) after calcination. SEM analysis showed the catalyst’s morphology (CaO and CaO/Zn) changes after undergoing calcination and zinc impregnation processes. In this study, eggshells were utilized as a potential solid catalyst for biodiesel synthesis through transesterification. The reusability of the catalyst was also investigated. The reused catalyst produced an average yield of 65%.
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Antunes, Isabel, Luís C. M. Ruivo, Luís A. C. Tarelho e Jorge R. Frade. "Ca2Fe2O5-Based WGS Catalysts to Enhance the H2 Yield of Producer Gases". Catalysts 14, n. 1 (21 dicembre 2023): 12. http://dx.doi.org/10.3390/catal14010012.
Testo completoAbstract (sommario):
Ca2Fe2O5-based catalysts were synthesized from siderite and calcite precursors, which were processed in the form of pelletized samples and tested as water gas shift catalysts. Catalytic tests were performed in a tubular reactor, at temperatures in the range 400–500 °C and with different H2O:CO ratios, diluted with N2; this demonstrates the positive impact of Ca2Fe2O5 on conversion of CO and H2 yield, relative to corresponding tests without catalyst. The catalytic performance was also remarkably boosted in a microwave-heated reactor, relative to conventional electric heating. Post-mortem analysis of spent catalysts showed significant XRD reflections of spinel phases (Fe3O4 and CaFe2O4), and SiO2 from the siderite precursor. Traces of calcium carbonate were also identified, and FTIR analysis revealed relevant bands ascribed to calcium carbonate and adsorbed CO2. Thermodynamic modelling was performed to assess the redox tolerance of Ca2Fe2O5-based catalysts in conditions expected for gasification of biomass and thermochemical conditions at somewhat lower temperatures (≤500 °C), as a guideline for suitable conditions for water gas shift. This modelling, combined with the results of catalytic tests and post-mortem analysis of spent catalysts, indicated that the O2 and CO2 storage ability of Ca2Fe2O5 contributes to its catalytic activity, suggesting prospects to enhance the H2 content of producer gases by water gas shift.
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Dobosz, Justyna, Sylwia Hull e Mirosław Zawadzki. "Catalytic activity of cobalt and cerium catalysts supported on calcium hydroxyapatite in ethanol steam reforming". Polish Journal of Chemical Technology 18, n. 3 (1 settembre 2016): 59–67. http://dx.doi.org/10.1515/pjct-2016-0049.
Testo completoAbstract (sommario):
Abstract In this paper, Co,Ce/Ca10(PO4)6(OH)2 catalysts with various cobalt loadings for steam reforming of ethanol (SRE) were prepared by microwave-assisted hydrothermal and sol-gel methods, and characterized by XRD, TEM, TPR-H2, N2 adsorption-desorption measurements and cyclohexanol (CHOL) decomposition tests. High ethanol conversion (close to 100%) was obtained for the catalysts prepared by both methods but these ones prepared under hydrothermal conditions (HAp-H) ensured higher hydrogen yield (3.49 mol H2/mol C2H5OH) as well as higher amount of hydrogen formed (up to 70%) under reaction conditions. The superior performance of 5Co,10Ce/HAp-H catalyst is thought to be due to a combination of factors, including increased reducibility and oxygen mobility, higher density of basic sites on its surface, and improved textural properties. The results also show a significant effect of cobalt loading on catalysts efficiency in hydrogen production: the higher H2 yield exhibit catalysts with lower cobalt content, regardless of the used synthesis method.
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Kingkam, Wilasinee, Jirapa Maisomboon, Khemmanich Khamenkit, Sasikarn Nuchdang, Kewalee Nilgumhang, Sudarat Issarapanacheewin e Dussadee Rattanaphra. "Preparation of CaO@CeO2 Solid Base Catalysts Used for Biodiesel Production". Catalysts 14, n. 4 (4 aprile 2024): 240. http://dx.doi.org/10.3390/catal14040240.
Testo completoAbstract (sommario):
The study investigated the use of CeO2 extracted from monazite with calcium oxide (CaO) as a solid catalyst for biodiesel production. The wet impregnation method was used to produce CaO@CeO2 mixed-oxide catalysts with 0–50 wt.% CaO. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and a Fourier transform infrared spectrometer (FTIR) was used to characterize the catalysts. In order to determine the optimal preparation conditions, the effect of different CaO compositions on the performance of CaO@CeO2 mixed-oxide catalysts was examined. The catalytic activity of the CaO@CeO2 catalyst for the transesterification reaction of palm oil to produce biodiesel was studied. The results show that the optimum yield of biodiesel can reach 97% fatty acid methyl ester over the 30CaO@CeO2 catalyst at the reaction conditions of 5 wt.% catalysts, methanol-to-oil molar ratio of 9:1, with a reaction temperature of 65 °C within 30 min. The results show that the high catalytic activity and stability of the CaO@CeO2 catalyst make it a promising candidate for industrial-scale biodiesel production. Further study is needed to improve the stability and efficiency of catalysts in transesterification reactions to achieve a high FAME yield using long-life-span catalysts. Moreover, it is necessary to investigate the economic feasibility of this process for application in large-scale biodiesel production.
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Chukwuemeke U, Wisdom, Ruth Oghenerukevwe Eyankware U e Michael Chika Egwunyenga. "INVESTIGATION OF THE POTENTIAL OF WASTE BONES AS A CATALYST IN BIOFUEL PRODUCTION". Journal of Wastes and Biomass Management 5, n. 1 (16 febbraio 2023): 15–21. http://dx.doi.org/10.26480/jwbm.01.2023.15.21.
Testo completoAbstract (sommario):
It has recently come to light that inappropriate waste management (particularly of animal bones) is a major contributor to environmental degradation on a global scale. Instead, it would be extremely beneficial to the economy if the bioeconomy civilization could find novel applications for these discards. Biodiesel’s output can be put to good use as a heterogeneous catalyst in the effective recycling of animal bone. Ca-based catalysts produced from discarded bones, have been extensively studied in the transesterification reaction due to their high catalytic activity and abundant feedstock. Calcium oxide, a common mineral, can be used to create heterogeneous catalysts (in the form of discarded bones). However, process improvements are required to make calcium oxide-based catalysts suitable for industrial use. This research summarizes the sources of waste animal bones, provides context for the recent advances in the development of various Ca-based catalysts derived from waste animal bones, characterized a calcium oxide-based catalyst derived from waste animal bones, and details its application in biodiesel production. In this work, waste bones were modified by calcination at 9500C for 3h. The catalyst was analyzed using scanning electron microscopy (SEM) for its morphological structure, Fourier transform infrared spectroscopy (FTIR), for its functional group, X-ray fluorescence (XRF), for its elemental composition, thermogravimetric analysis (TGA), for thermal stability and Brunauer Emmett Teller (BET) surface area analysis. Overall, raw sample was found to have no effect on the waste bone, while high temperature calcination greatly affected the pore size, surface area, composition, and thermal decomposition profile of the waste bone sample. According to the study’s findings, used animal bones can be used to create catalysts that are appropriate for trans-esterifying a variety of oil sources into high-quality biodiesel. This increases the total energy and atom-efficiency of both conventional and new chemical processes while also making the system more cost-effective and ecologically benign. This discovery will encourage scientists to look into possible wastes of bones and pave the way for a more cost-effective and ecologically friendly way to make biodiesel and should also continue to be evaluated for the likelihood of their use in the commercial sector.
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Alam, W. S., F. Abraar, V. Pramananda e Z. Masyithah. "Synthesis of microalgae-based methyl ester using calcium glyceroxide catalyst derived from duck eggshells and crude glycerol in the n-hexane co-solvent system". IOP Conference Series: Earth and Environmental Science 1356, n. 1 (1 giugno 2024): 012114. http://dx.doi.org/10.1088/1755-1315/1356/1/012114.
Testo completoAbstract (sommario):
Abstract The synthesis of microalgae-based methyl ester has attracted the interest of researchers since microalgae have a high lipid content and can proliferate. Chlorella vulgaris, with its 63% lipid content on a dry basis, holds promise for methyl ester production. Heterogeneous catalysts, particularly calcium glyceroxide (Ca[O(OH)2C3H5]), play a crucial role in ester manufacturing due to their high catalytic activity. The synthesis of the calcium glyceroxide catalyst involves duck eggshells as a calcium source and crude glycerol. Optimal methyl ester production is achieved by employing n-hexane as a co-solvent for efficient microalgae oil dissolution. This research focuses on synthesizing and characterizing the calcium glyceroxide catalyst derived from duck eggshells and crude glycerol, emphasizing its application in manufacturing microalgae-based methyl esters with n-hexane as the co-solvent. Methyl ester synthesis variables include a 55°C reaction temperature, a 1.5% microalgae-derived catalyst, and a 9:1 methanol to microalgae ratio. FTIR functional group analysis identifies hydroxyl (O-H) groups from crude glycerol bound to calcium at 3345.71 cm−1, along with C-H group vibrations from crude glycerol bound to calcium at 2941.80 cm−1. SEM morphological analysis reveals aggregate formation on the calcium glyceroxide catalyst, indicating potential active sites. Utilizing the calcium glyceroxide catalyst for methyl ester synthesis yields a promising 62.42% yield. GC characterization demonstrates a methyl ester purity of 72.09%, with methyl palmitate as the predominant component at 30.927%. This study underscores the efficient use of the synthesized calcium glyceroxide catalyst for microalgae-based methyl ester production, showcasing its potential for sustainable biodiesel synthesis.
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Harder, Sjoerd. "From Limestone to Catalysis: Application of Calcium Compounds as Homogeneous Catalysts". Chemical Reviews 110, n. 7 (14 luglio 2010): 3852–76. http://dx.doi.org/10.1021/cr9003659.
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Nargiz Baghirova, Nargiz Baghirova. "RELATİONSHİP BETWEEN ELECTRICAL AND CATALYTIC IN THE REACTION OF CONVERSION OF ETHANOL TO ACETONE". PAHTEI-Procedings of Azerbaijan High Technical Educational Institutions 14, n. 03 (21 marzo 2022): 89–95. http://dx.doi.org/10.36962/pahtei14032022-89.
Testo completoAbstract (sommario):
Low molecular weight ketones are among the most important products widely used in industry, however, the existing methods for their production are multistage. The significant disadvantages of these methods include the implementation of individual stages at high temperatures and pressures. As a result, the development of more economical and easy-to-implement processes is presented as an actual task for the basic organic synthesis industry. Recently, ethanol has been considered as a possible feedstock for the production of acetone. The prospect of using ethanol as a feedstock is due to the large renewable resources for its production. The growing interest in recent years in the production of ethanol by processing agricultural products and waste from the food and woodworking industries will undoubtedly stimulate further development of the method of producing acetone from ethanol. The catalytic conversion of ethanol to acetone is a relatively new method for producing acetone and, naturally, the number of publications devoted to this process is relatively small. In previously published works, as a rule, the issues of the mechanism of the process, as well as the relationship between the physicochemical and catalytic properties of the proposed active systems in these reactions, are not considered in detail. Active and selective catalysts were selected for the conversion reaction of ethanol to acetone, the mechanism of the process and the relationship between the physicochemical and catalytic properties of the activated sample were studied. The experiments were carried out on an active catalyst with the composition ZnO:CaO=9:1 The main provisions of the electronic theory of catalysis are developed in application to semi¬con-ductors, since, firstly, the theory of semiconductors is now more developed, and secondly, most of the catalysts used in practice belong to semiconductors. The surface of a semiconductor is the protection of two phases: a solid body-gas. The approach to this boundary from the side of the gaseous environment is essential for catalysis. The environment affects the surface and volume of the solid body. The influence of the environment is carried out through adsorption, as a result, the Fermi level shifts, and the electrophysical pro¬pert¬ies of catalysts change in the processes of adsorption and catalysis. Reactions of heterogeneous-catalytic transformation of low molecular weight alcohols are of great practical importance. The relevance of catalytic transformations of ethanol into various valuable products is the most important task of modern catalytic chemistry. To elucidate the mechanism of these reactions, a necessary step is to study the nature of the electronic interaction of reactants with a solid body, since the vast majority of catalysts of heterogeneous-catalytic oxidation - metal oxides, semiconductors, so especially promising is to involve methods for studying the electro physical properties of the surface. Changing these properties and studying the nature of their change in the atmosphere of the reactants, it is possible obtain valuable information about the nature of the electronic interaction of the reactant-catalyst. The works carried out in this direction showed that in most cases the process of chemisorption is accompanied by the appearance of an additional surface potential, indicating the charging of the surface in the presence of a particular reactant. The electrical and catalytic properties of a series of active zinc-calcium oxide catalysts were studied (their activity was also studied in previous experiments). The study of the electrical properties of the catalyst is of the greatest interest for elucidating the mechanism of reactions, since they can provide information about the nature of electronic transitions that limit the course of the reaction. The number of different factors determines the catalytic activity of a solid body. Each of these factors can correlate with certain properties of a solid body. When comparing catalytic and electrophysical properties electrical conductivity is most often measured. Measuring on the same catalyst sample under the same conditions of conductivity change can provide useful information about mechanism of action of the catalyst and the course of the catalytic reaction. Studies of the electrical conductivity of the synthesized catalysts have shown that all the catalysts studied are semiconductors. This article shows the relationship between the electrical and catalytic properties of zinc-calcium oxide catalysts. Keywords: catalyst, electrical conductivity, activation energy, adsorption, ethanol, acetone.
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Buasri, Achanai, Tidarat Rattanapan, Chalida Boonrin, Chosita Wechayan e Vorrada Loryuenyong. "Oyster andPyramidellaShells as Heterogeneous Catalysts for the Microwave-Assisted Biodiesel Production fromJatropha curcasOil". Journal of Chemistry 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/578625.
Testo completoAbstract (sommario):
Microwave-assisted biodiesel production via transesterification ofJatropha curcasoil with methanol using solid oxide catalyst derived from waste shells of oyster andPyramidellawas studied. The shells were calcined at 900°C for 2 h and calcium oxide (CaO) catalyst characterizations were carried out by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), and the Brunauer-Emmett-Teller (BET) surface area measurements. The effects of reaction variables such as reaction time, microwave power, methanol/oil molar ratio, and catalyst loading on the yield of biodiesel were investigated. Reusability of waste shell catalyst was also examined. The results indicated that the economic and environmentally friendly catalysts derived from oyster andPyramidellashells showed good reusability and had high potential to be used as biodiesel production catalysts under microwave-assisted transesterification ofJatropha curcasoil with methanol.
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Yan, Dengjie, Lingxin Kong, Baoqiang Xu e Bin Yang. "One−Step Synthesis Strategy for a Platinum−Based Alloy Catalyst Designed via Crystal−Structure Prediction". Molecules 29, n. 23 (28 novembre 2024): 5634. http://dx.doi.org/10.3390/molecules29235634.
Testo completoAbstract (sommario):
The industrial application of polymer electrolyte membrane fuel cells is limited by the high cost of platinum catalysts. In this study, we developed a one−step synthesis strategy for low−platinum alloy catalysts based on crystal−structure predictions. Using this method, we successfully prepared a low−platinum alloy catalyst, i.e., CaPt2, which exhibits the same structure as its theoretically predicted counterpart in a single step via arc melting. There was no hazardous waste emission during the preparation of the alloy catalyst. Electrons were successfully enriched on the surfaces of platinum atoms, and the electronic structures of the platinum atoms were adjusted. The migration of oxygen intermediates during oxygen reduction was determined via an extensive oxygen−intermediate adsorption site test. The reaction path for the oxygen reduction process was determined. Electronic−structure analysis revealed the interaction mechanism between the oxygen intermediate and the platinum atom on the catalyst surface. The incorporation of calcium atoms into the alloy catalyst effectively improved the adsorption/dissociation state of the oxygen intermediates on the catalyst surface. Meanwhile, the molar fraction of platinum atoms in the CaPt2 alloy catalyst reduced by 33%, thus decreasing the feedstock cost of the catalyst. The double reduction in raw materials and manufacturing costs is conducive to the popularization and application of alloy catalysts. This study provides a reference for the design and production of other functional catalysts.
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Modekwe, Helen Uchenna, Messai Adenew Mamo, Michael Olawale Daramola e Kapil Moothi. "Catalytic Performance of Calcium Titanate for Catalytic Decomposition of Waste Polypropylene to Carbon Nanotubes in a Single-Stage CVD Reactor". Catalysts 10, n. 9 (8 settembre 2020): 1030. http://dx.doi.org/10.3390/catal10091030.
Testo completoAbstract (sommario):
Calcium titanate mixed metal oxides with different contents were used as supports for NiMo catalyst prepared by the sol–gel method. The activities of these catalysts were tested in the catalytic decomposition of waste polypropylene (PP) for the synthesis of carbon nanotubes (CNTs) using a single-stage chemical vapor deposition technique. The physico-chemical properties of the catalysts and deposited carbon over the catalysts were checked by X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-programmed reduction (TPR), N2 physisorption, transmission electron microscopy (TEM), Raman spectroscopy, and thermogravimetric analysis (TGA). The TEM and XRD results presented a high dispersion of the active metal species on the surface of the support materials. The result showed that increasing the support content led to an increased crystallite size of the catalysts and a resultant reduction in CNTs yield from 44% to 35%. NiMo-supported CaTiO3 catalyst displayed good catalytic activity and stability toward CNTs growth. Furthermore, the effect of calcination temperature on the morphology, yield, and quality of CNTs was also studied, and it was observed that thermal treatment up to 700 °C could produce well graphitized, high-quality, and high-yield CNTs from the waste PP.
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Zhang, Yi Jun, e Sheng Yong Liu. "Solid- Alkali Catalyst of Mussel Shell Used in Producing Biodiesel". Advanced Materials Research 608-609 (dicembre 2012): 206–9. http://dx.doi.org/10.4028/www.scientific.net/amr.608-609.206.
Testo completoAbstract (sommario):
Calcium dioxide can catalyze soybean oil to obtain biodiesel in triglyceride transesterification. Waste mussel shells were utilized as a source of calcium oxide. The shell was calcined in N2 at 1000°C with optimum time of 2 h to obtain active CaO catalysts. Parametric studies have been investigated and perfect conditions were found to be methanol/oil mole ratio, 9:1; catalyst amount, 4wt%; reaction temperature, 65°C; stirring rate of 450 round per minute; reaction time, constant 3h; methyl esters conversion above 98% . Reusability results improved that the prepared catalyst is able to be reemployed up to 9 times. These results indicate waste mussel shell combusted at high temperature can be reused in biodiesel production as a low cost catalyst.
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Ronduda, Hubert, Magdalena Zybert, Wojciech Patkowski, Dariusz Moszyński, Aleksander Albrecht, Kamil Sobczak, Artur Małolepszy e Wioletta Raróg-Pilecka. "Co nanoparticles supported on mixed magnesium–lanthanum oxides: effect of calcium and barium addition on ammonia synthesis catalyst performance". RSC Advances 13, n. 7 (2023): 4787–802. http://dx.doi.org/10.1039/d3ra00133d.
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