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Trigoura, Leslie, Yalan Xing i Bhanu P. S. Chauhan. "Recyclable Catalysts for Alkyne Functionalization". Molecules 26, nr 12 (9.06.2021): 3525. http://dx.doi.org/10.3390/molecules26123525.
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In this review, we present an assessment of recent advances in alkyne functionalization reactions, classified according to different classes of recyclable catalysts. In this work, we have incorporated and reviewed the activity and selectivity of recyclable catalytic systems such as polysiloxane-encapsulated novel metal nanoparticle-based catalysts, silica–copper-supported nanocatalysts, graphitic carbon-supported nanocatalysts, metal organic framework (MOF) catalysts, porous organic framework (POP) catalysts, bio-material-supported catalysts, and metal/solvent free recyclable catalysts. In addition, several alkyne functionalization reactions have been elucidated to demonstrate the success and efficiency of recyclable catalysts. In addition, this review also provides the fundamental knowledge required for utilization of green catalysts, which can combine the advantageous features of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis.
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Hauli, Latifah, Karna Wijaya i Ria Armunanto. "Preparation of Cr Metal Supported on Sulfated Zirconia Catalyst". Materials Science Forum 948 (marzec 2019): 221–27. http://dx.doi.org/10.4028/www.scientific.net/msf.948.221.
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Catalyst of Chromium (Cr) metal supported on sulfated zirconia (SZ) was prepared by wet impregnation method. This study aim to determine the optimal concentration of Cr metal that impregnated on SZ catalyst. Preparation of catalyst was conducted at different concentrations of Cr metal (0.5%, 1%, 1.5% (w/w)), impregnated on SZ catalyst, then followed by the calcinationand reduction process. Catalysts were charaterized by FTIR, XRD, XRF, SAA, TEM, and acidity test. The results showed the Cr/SZ 1% had the highest acidity value of 8.22 mmol/g which confirmed from FTIR spectra. All the crystal phase of these catalysts were in monoclinic. The specific surface area increased with the increasing of Cr metal concentration on SZ catalyst and the isotherm adsorption-desorption of N2 gas observed all the catalysts as mesoporous material. The impregnation process formed particles agglomeration.
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Mardwita, Mardwita, Eka Sri Yusmartini i Nidya Wisudawati. "Effects of Cobalt and Chromium Loadings to The Catalytic Activities of Supported Metal Catalysts in Methane Oxidation". Bulletin of Chemical Reaction Engineering & Catalysis 15, nr 1 (15.01.2020): 213–20. http://dx.doi.org/10.9767/bcrec.15.1.6320.213-220.
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A series of alumina supported cobalt and chromium catalysts with different metal loadings were prepared by impregnation method. Six types of alumina supported cobalt and chromium catalysts contained 5 wt%, 10 wt%, and 15 wt% loadings were produced and tested in methane oxidation. The catalysts were characterized by using x-ray diffraction (XRD) and carbon monoxide chemisorption (CO chemisorption). The XRD results do not confirmed any features of cobalt and chromium metal. The metal sizes for both catalysts were larger in high loading as shown by CO chemisorption results. Methane conversion results showed that the conversion increases with increasing the metal loading, however supported chromium catalysts were higher in activities compared to supported cobalt catalysts. Thermal stability tests on 15 wt% Co/Al and 15 wt% Cr/Al catalyst showed that supported chromium catalyst is more stable and maintain the particle size due to its strong interaction with support, while supported cobalt catalyst decrease in methane conversion due to deactivation of the catalyst. Copyright © 2020 BCREC Group. All rights reserved
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Mistri, Rajib, i Bidyapati Kumar. "Supported Transition Metal Catalysts for Organic Fine Chemical Synthesis: A Review". Asian Journal of Chemistry 33, nr 3 (2021): 489–98. http://dx.doi.org/10.14233/ajchem.2021.23025.
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Transition metal catalysts play an important role for synthesis of industrially and laboratory important organic fine chemicals to control the selectivity, activity and stability. In this review, we focus on mainly transition metal based supported catalyst, mainly oxide supported catalyst for heterogeneous catalytic hydrogenation and oxidation of some synthetically important organic molecules. First we discuss the industrially important catalytic organic synthetic reactions. This is followed by the role of supported metal catalysts in the heterogeneous synthetic catalytic reactions with specific attention to hydrogenation and oxidation of organic molecules. The role of base metals and noble metals in monometallic and bimetallic catalysts are then discussed. Some synthetic routes for preparation of oxide supported metal catalysts are also discussed. Finally, a general discussion of the metal-support interaction (MSI) in oxide supported metal catalysts is made.
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Hepburn, J. S. "EPMA/TEM characterization of a Pt/Al2O3 catalyst with a nonuniform internal distribution". Proceedings, annual meeting, Electron Microscopy Society of America 47 (6.08.1989): 274–75. http://dx.doi.org/10.1017/s0424820100153348.
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The internal distribution of catalytically active metal within a supported metal catalyst can determine its activity, selectivity, and durability. Since the early 1950s, electron probe microanalysis has grown into a mature and widely available technique. By providing quantitative elemental analysis from volumes on the order of 1μm3, EPMA is uniquely suited for the study of metal concentration profiles in supported metal catalysts. However, independent knowledge of metal particle size or dispersion is needed to identify the catalytically active fraction of deposited metal. Most available techniques for metal particle size determination are indirect methods such as selective chemisorption. The transmission electron microscope is the only available device which is capable of resolving metal particles on the order of lnm in diameter. For years, the EPMA has been used in determining internal distributions of deposited metal within supported catalysts, while the TEM has been used to observe supported metal catalyst particles on powdered supports. However, there has been no study that combines both EPMA and TEM which attempts to furnish the information about a supported metal catalyst which is truly desired (its internal distribution of catalytically active metal). In the present work, a Pt/Al2O3 catalyst with a nonuniform internal distribution of deposited Pt was analyzed by incorporating EPMA and TEM.
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Patil, Siddappa A., Shivaputra A. Patil i Renukadevi Patil. "Magnetic Nanoparticles Supported Carbene and Amine Based Metal Complexes in Catalysis". Journal of Nano Research 42 (lipiec 2016): 112–35. http://dx.doi.org/10.4028/www.scientific.net/jnanor.42.112.
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Catalysis is one of the hottest research topics in chemistry. In recent years, metal complexes attracted great interest as catalysts towards various types of organic reactions. However, these catalysts, in most cases, suffer from the deficits during their recovery, recycling and the difficulty in separation of catalysts from the products. Therefore, the design and synthesis of recoverable and recyclable catalyst is very important aspect in catalysis. The aim of this review article is to highlight the speedy growth in the synthesis and catalytic applications of magnetic nanoparticles (Fe3O4, MNPs) supported N-heterocyclic carbene (NHC) and amine based metal complexes in various organic reactions. Furthermore, these catalysts can be easily separated from the reaction media with the external magnet and reused various times without a substantial loss of catalytic activity.
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Gökağaç, Gülsün, i Brendan J. Kennedy. "Carbon Supported Pt+Os Catalysts for Methanol Oxidation". Zeitschrift für Naturforschung B 57, nr 2 (1.02.2002): 193–201. http://dx.doi.org/10.1515/znb-2002-0211.
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11% Pt/C, 10% Pt + 1%Os/C, 9% Pt + 2%Os/C, 8% Pt + 3%Os/C, 7% Pt + 4%Os/C, 6% Pt + 5%Os/C and 5%Pt + 6% Os/C catalysts have been prepared for methanol oxidation reaction. Transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and cyclic voltammetry have been used to understand the nature of the species present in these catalysts. 7% Pt + 4% Os/C was the most active catalyst, while 8% Pt + 3% Os/C was the least active one. It is found that the metal particle size and distribution on the carbon support, the surface composition and the oxidation states of the metal particles, the metal-metal and metal support interactions are important parameters to define the activity of the catalyst.
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Ye, Ke, Ying Liu, Shubin Wu i Junping Zhuang. "Efficient catalytic liquefaction of organosolv lignin over transition metal supported on HZSM-5". BioResources 17, nr 2 (25.03.2022): 2275–95. http://dx.doi.org/10.15376/biores.17.2.2275-2295.
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In this work, the catalytic liquefaction of eucalyptus organosolv lignin (EOL) over hydrogen type-zeolite socony mobile-five (HZSM-5) zeolite supported transition metals in an ethanol system was studied, and a cheap transition metal NiCr/HZSM-5 catalyst was prepared. Among them, nickel and chromium proved to have a good synergistic effect, which could remarkably enhance the acidity of the catalyst surface, and the catalytic effect was better than Ru-based precious metal catalysts and commercial Raney Ni catalysts. Meanwhile, the optimal reaction process of NiCr/HZSM-5 and Raney Ni catalyst for synergistic catalysis of EOL was explored. Under the optimal process conditions, the lignin liquefaction rate reached 95.9%, the monophenol yield was 8.64%, and the char content was only 2.08%. Furthermore, 1H-13C heteronuclear single quantum correlation nuclear magnetic resonance (1H-13C HSQC NMR) showed that the β-O-4, β-β, and β-5 linkages of lignin were effectively broken. Thus, a higher liquefaction rate of lignin was realized, which provided the possibility for further comprehensive utilization of lignin.
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Sasaki, Teruyoshi, Yusuke Horino, Tadashi Ohtake, Kazufumi Ogawa i Yoshifumi Suzaki. "A Highly Efficient Monolayer Pt Nanoparticle Catalyst Prepared on a Glass Fiber Surface". Catalysts 10, nr 5 (25.04.2020): 472. http://dx.doi.org/10.3390/catal10050472.
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Over the past few years, various nanoparticle-supported precious metal-based catalysts have been investigated to reduce the emission of harmful substances from automobiles. Generally, precious metal nanoparticle-based exhaust gas catalysts are prepared using the impregnation method. However, these catalysts suffer from the low catalytic activity of the precious metal nanoparticles involved. Therefore, in this study, we developed a novel method for preparing highly efficient glass fiber-supported Pt nanoparticle catalysts. We uniformly deposited a single layer of platinum particles on the support surface using a chemically adsorbed monomolecular film. The octane combustion performance of the resulting catalyst was compared with that of a commercial catalyst. The precious metal loading ratio of the proposed catalyst was approximately seven times that of the commercial catalyst. Approximately one-twelfth of the mass of the proposed catalyst exhibited a performance comparable to that of the commercial catalyst. Thus, the synthesis method used herein can be used to reduce the weight, size, and manufacturing cost of exhaust gas purification devices used in cars.
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Mita, Yasuhiro. "Development of metal-supported catalyst." DENKI-SEIKO[ELECTRIC FURNACE STEEL] 61, nr 2 (1990): 124–35. http://dx.doi.org/10.4262/denkiseiko.61.124.
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Kim, Soohyun, Yunxia Yang, Renata Lippi, Hokyung Choi, Sangdo Kim, Donghyuk Chun, Hyuk Im, Sihyun Lee i Jiho Yoo. "Low-Rank Coal Supported Ni Catalysts for CO2 Methanation". Energies 14, nr 8 (7.04.2021): 2040. http://dx.doi.org/10.3390/en14082040.
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As renewable energy source integration increases, P2G technology that can store surplus renewable power as methane is expected to expand. The development of a CO2 methanation catalyst, one of the core processes of the P2G concept, is being actively conducted. In this work, low-rank coal (LRC) was used as a catalyst support for CO2 methanation, as it can potentially enhance the diffusion and adsorption behavior by easily controlling the pore structure and composition. It can also improve the process efficiency owing to its simplicity (no pre-reduction step) and high thermal conductivity, compared to conventional metal oxide-supported catalysts. A screening of single metals (Ni, Co, Ru, Rh, and Pd) on LRC was performed, which showed that Ni was the most active. When Ni on the LRC catalyst was doped with a promoter (Ce and Mg), the CO2 conversion percentage increased by >10% compared to that of the single Ni catalyst. When the CO2 methanation activity was compared at 250–500 °C, the Ce-doped Ni/Eco and Mg-doped Ni/Eco catalysts showed similar or better activity than the commercial metal oxide-supported catalyst. In addition, the catalytic performance remained stable even after the test for an extended time (~200 h). The results of XRD, TEM, and TPR showed that highly efficient LRC-based CO2 methanation catalysts can be made when the metal dispersion and composition are modified.
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Wardhani, Sri, Danar Purwonugroho i Diah Mardiana. "PHENOL OXIDATION USING NATURAL ZEOLITE SUPPORTED METAL ION CATALYST". Indonesian Journal of Chemistry 8, nr 2 (17.06.2010): 215–18. http://dx.doi.org/10.22146/ijc.21636.
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Phenol which contained in waste water has to be reduced and it could be done by oxygen oxidation. In order to increase the rate of reaction it was needed a catalyst. In this research the capability of various catalysts, namely zeolite-Zn(II), zeolite-Cu(II) and zeolite-Co(II)in oxidation of phenol has been investigated. The aim of this research was to study the type of metal ion catalyst towards the percentage of oxidated phenol. The oxidation process were carried out in an aqueous phenol of 100 ppm with oxygen flow rate of 200 mL/min. in the presence of catalysts with 0.2M of initial impregnation concentration. The capabilities of catalysts were performed by calculating the activation energy and it was done at two different temperatures, i.e. 70 and 90 oC. The percentage of oxidated phenol was determinated by measuring its concentration using UV-VIS spectrophotometer. In addition, the impregnated metal was calculated by measuring the ion concentration remains in the filtrate solution and it was determined using Atomic Absorption Spectrophotometer. The results showed that metal ion types affected the catalytic activity. The order of phenol oxidationactivity decreased as Co(II) > Cu(II) > Zn(II). The surface characteristics of catalysts were supported by pore volume and pore diameter i.e 0.009 cm3/g and 16.59 Å for Zn(II) whereas specific surface area was 10.32 m2/g for Zn(II), 0.004 cm3/g and 24.37 Å for Cu(II) whereas specific surface area was 3.57 m2/g for Cu(II), 0.001 cm3/g and 19.63 Å for Co(II) whereas specific surface area was 10.26m2/g for Co(II). Keywords: phenol,natural zeolite, catalyst, oxidation
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Zhang, Xiaolong, Shilei Jin, Yuhan Zhang, Liyuan Wang, Yang Liu i Qian Duan. "One-Pot Facile Synthesis of Noble Metal Nanoparticles Supported on rGO with Enhanced Catalytic Performance for 4-Nitrophenol Reduction". Molecules 26, nr 23 (30.11.2021): 7261. http://dx.doi.org/10.3390/molecules26237261.
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In this study, reduced graphene oxide (rGO)-supported noble metal (gold, silver, and platinum) nanoparticle catalysts were prepared via the one-pot facile co-reduction technique. Various measurement techniques were used to investigate the structures and properties of the catalysts. The relative intensity ratios of ID/IG in rGO/Au, rGO/Ag, rGO/Pt, and GO were 1.106, 1.078, 1.047, and 0.863, respectively. The results showed the formation of rGO and that noble metal nanoparticles were decorated on rGO. Furthermore, the catalytic activities of the designed nanocomposites were investigated via 4-nitrophenol. The catalysts were used in 4-nitrophenol reduction. The catalytic performance of the catalysts was evaluated using the apparent rate constant k values. The k value of rGO/Au was 0.618 min−1, which was higher than those of rGO/Ag (0.55 min−1) and rGO/Pt (0.038 min−1). The result proved that the rGO/Au catalyst exhibited a higher catalytic performance than the rGO/Ag catalyst and the rGO/Pt catalyst. The results provide a facile method for the synthesis of rGO-supported nanomaterials in catalysis.
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Pan, M., J. M. Cowley, I. Y. Chan i R. Garcia. "Structure Studies of Supported Metal Catalyst Particles by Microdiffraction Technique". Proceedings, annual meeting, Electron Microscopy Society of America 45 (sierpień 1987): 202–3. http://dx.doi.org/10.1017/s0424820100125919.
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Understanding the structures of the small metal particles (<5nm) in supported metal catalysts can provide some basis for understanding the properties and performance of these catalysts. High resolution transmission electron microscopy (HRTEM) has been extensively used to characterize the structures of small particles in the past few years. As a complement to HRTEM, microdiffraction technique has its unique advantage of being able to provide local structure information within regions of diameter 1-2nm.In our VG HB-5 STEM an electron beam with diameter of 1-1.5nm can be easily generated at the specimen level and microdiffraction patterns from such small regions are routinely observed with the help of the attached optical system. Two series of catalyst samples, Pt/γ-Al2 O3 and Rh/CeO2 with various metal loadings and reduction temperatures, have been studied. The series of Pt/γ-Al2 O3 catalyst included both calcined and reduced samples. Both series of catalysts contain high dispersions of metal particles (<5nm). In the case of Rh/CeO2 Rh particles usually have sizes of 2-3nm.
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du Plessis, Hester, Roy Forbes, Werner Barnard, Alta Ferreira i Axel Steuwer. "In situ reduction study of cobalt model Fischer-Tropsch synthesis catalyst". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C948. http://dx.doi.org/10.1107/s2053273314090512.
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Fischer-Tropsch (FT) synthesis is an important process to manufacture hydrocarbons and oxygenated hydrocarbons from mixtures of carbon monoxide and hydrogen (syngas). The catalysis process occurs on for example cobalt metal surfaces at elevated temperatures and pressures. A fundamental understanding of the reduction pathway of supported cobalt oxides, and the intermediate species present during the activation, can assist in developing improved industrial supported cobalt catalysts. Measurements were done during in-situ hydrogen activation of a model Co/alumina catalyst using in-situ synchrotron X-ray powder diffraction and pair-distribution function (PDF) analysis. Strong metal-support interactions between the Co and the support1 can make the catalyst more stable towards sintering. The supported cobalt oxide catalyst precursors have to undergo reductive pre-treatments before their use as FT catalysts. During activation the cobalt oxides evolve, resulting in the formation of metallic cobalt depending on temperature, pressure of activation gases, concentration, time of exposure etc. The effect of hydrogen activation treatments on model catalysts were reported previously [1,2], however analysis of the alumina support phases was excluded from the interpretation by subtraction and normalisation. The PDF refinement accounted for all cobalt present in the catalyst sample and after reduction mainly Co(fcc) with a little Co(hcp) was found to be present. This is a novel approach to in situ PDF analysis of catalysts containing a mixture of phases [3].
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Yang, Hui, Hui Wang, Lisha Wei, Yong Yang, Yong-Wang Li, Xiao-dong Wen i Haijun Jiao. "Simple mechanisms of CH4 reforming with CO2 and H2O on a supported Ni/ZrO2 catalyst". Physical Chemistry Chemical Physics 23, nr 46 (2021): 26392–400. http://dx.doi.org/10.1039/d1cp04048k.
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To understand the metal–support interaction of oxide supported transition metal catalysts, we computed the reaction mechanisms of dry and steam reforming of methane on a tetragonal ZrO2(101) supported Ni catalyst.
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Kaewtrakulchai, Napat, Araya Smuthkochorn, Kanit Manatura, Gasidit Panomsuwan, Masayoshi Fuji i Apiluck Eiad-Ua. "Porous Biochar Supported Transition Metal Phosphide Catalysts for Hydrocracking of Palm Oil to Bio-Jet Fuel". Materials 15, nr 19 (22.09.2022): 6584. http://dx.doi.org/10.3390/ma15196584.
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The upgrading of plant-based oils to liquid transportation fuels through the hydrotreating process has become the most attractive and promising technical pathway for producing biofuels. This work produced bio-jet fuel (C9–C14 hydrocarbons) from palm olein oil through hydrocracking over varied metal phosphide supported on porous biochar catalysts. Relative metal phosphide catalysts were investigated for the highest performance for bio-jet fuel production. The palm oil’s fiber-derived porous biochar (PFC) revealed its high potential as a catalyst supporter. A series of PFC-supported cobalt, nickel, iron, and molybdenum metal phosphides (Co-P/PFC, Ni-P/PFC, Fe-P/PFC, and Mo-P/PFC) catalysts with a metal-loading content of 10 wt.% were synthesized by wet-impregnation and a reduction process. The performance of the prepared catalysts was tested for palm oil hydrocracking in a trickle-bed continuous flow reactor under fixed conditions; a reaction temperature of 420 °C, LHSV of 1 h−1, and H2 pressure of 50 bar was found. The Fe-P/PFC catalyst represented the highest hydrocracking performance based on 100% conversion with 94.6% bio-jet selectivity due to its higher active phase dispersion along with high acidity, which is higher than other synthesized catalysts. Moreover, the Fe-P/PFC catalyst was found to be the most selective to C9 (35.4%) and C10 (37.6%) hydrocarbons.
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Albano, Gianluigi, Antonella Petri i Laura Antonella Aronica. "Palladium Supported on Bioinspired Materials as Catalysts for C–C Coupling Reactions". Catalysts 13, nr 1 (16.01.2023): 210. http://dx.doi.org/10.3390/catal13010210.
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In recent years, the immobilization of palladium nanoparticles on solid supports to prepare active and stable catalytic systems has been deeply investigated. Compared to inorganic materials, naturally occurring organic solids are inexpensive, available and abundant. Moreover, the surface of these solids is fully covered by chelating groups which can stabilize the metal nanoparticles. In the present review, we have focused our attention on natural biomaterials-supported metal catalysts applied to the formation of C–C bonds by Mizoroki–Heck, Suzuki–Miyaura and Sonogashira reactions. A systematic approach based on the nature of the organic matrix will be followed: (i) metal catalysts supported on cellulose; (ii) metal catalysts supported on starch; (iii) metal catalysts supported on pectin; (iv) metal catalysts supported on agarose; (v) metal catalysts supported on chitosan; (vi) metal catalysts supported on proteins and enzymes. We will emphasize the effective heterogeneity and recyclability of each catalyst, specifying which studies were carried out to evaluate these aspects.
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Fornalczyk, A., M. Kraszewski, J. Willner, J. Kaduková, A. Mrážiková, R. Marcinčáková i O. Velgosová. "Dissolution of Metal Supported Spent Auto Catalysts in Acids". Archives of Metallurgy and Materials 61, nr 1 (1.03.2016): 233–36. http://dx.doi.org/10.1515/amm-2016-0043.
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Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported) Converters (MSC), catalytic functions are performed by the Platinum Group Metals (PGM): Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from the ceramic carriers, however, the issue of platinum recovery from metal supported catalysts has not been studied sufficiently yet. The paper presents preliminary results of dissolution of spent automotive catalyst on a metal carrier by means of acids: H2SO4, HCl, HNO3, H3PO4. The main assumption of the research was the dissolution of base metals (Fe, Cr, Al) from metallic carrier of catalyst, avoiding dissolution of PGMs. Dissolution was the most effective when concentrated hydrochloric acid, and 2M sulfuric acid (VI) was used. It was observed that the dust, remaining after leaching, contained platinum in the level of 0.8% and 0.7%, respectively.
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Shinde, Preeti S., Pradnya S. Suryawanshi, Kanchan K. Patil, Vedika M. Belekar, Sandeep A. Sankpal, Sagar D. Delekar i Sushilkumar A. Jadhav. "A Brief Overview of Recent Progress in Porous Silica as Catalyst Supports". Journal of Composites Science 5, nr 3 (6.03.2021): 75. http://dx.doi.org/10.3390/jcs5030075.
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Porous silica particles have shown applications in various technological fields including their use as catalyst supports in heterogeneous catalysis. The mesoporous silica particles have ordered porosity, high surface area, and good chemical stability. These interesting structural or textural properties make porous silica an attractive material for use as catalyst supports in various heterogeneous catalysis reactions. The colloidal nature of the porous silica particles is highly useful in catalytic applications as it guarantees better mass transfer properties and uniform distribution of the various metal or metal oxide nanocatalysts in solution. The catalysts show high activity, low degree of metal leaching, and ease in recycling when supported or immobilized on porous silica-based materials. In this overview, we have pointed out the importance of porous silica as catalyst supports. A variety of chemical reactions catalyzed by different catalysts loaded or embedded in porous silica supports are studied. The latest reports from the literature about the use of porous silica-based materials as catalyst supports are listed and analyzed. The new and continued trends are discussed with examples.
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Maru, Minaxi S., Parth Patel, Noor-ul H. Khan i Ram S. Shukla. "Copper Hydrotalcite (Cu-HT) as an Efficient Catalyst for the Hydrogenation of CO2 to Formic Acid". Current Catalysis 9, nr 1 (10.09.2020): 59–71. http://dx.doi.org/10.2174/2211544709999200413110411.
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: Hydrogenation of CO2 to energy-rich products over heterogeneous metal catalysts has gained much attention due to their commercial applications. Specifically, the first-row transition metal catalysts are very rarely reported and discussed for the production of formic acid from the hydrogenation of CO2. Herein, hydrotalcite supported copper metal has shown activity and efficiency to produce formic acid from the hydrogenation of CO2, without adding any additional base or promoter and was effectively recycled 4 times after separating by simple filtration without compromising the formic acid yield. Hydrotalcite supported copper-based catalyst (Cu-HT) was synthesized through the coprecipitation method and used as a heterogeneous catalyst for the hydrogenation of CO2. The precise copper metal content determined by ICP in Cu-HT is 0.00944 mmol. The catalyst afforded maximum TOF, 124 h-1 under the employed reaction conditions: 100 mg catalyst, 60 °C, 60 bar total pressure of CO2/H2 (1:1, p/p) with 60 mL of mixed methanol:water (5:1, v/v) solvent. Cu-HT catalyst was synthesised and thoroughly characterized by FT-IR, PXRD, SEM, TEM, XPS and BET surface area. The first-order kinetic dependence with respect to the catalyst amount, partial pressures of CO2, and of H2 was observed and a plausible reaction mechanism is suggested. Background: CO2 hydrogenation to energy-rich products over heterogeneous metal catalysts has gained much attention due to their commercial applications. Specifically, the first-row transition metal catalysts are very rarely reported and discussed for the production of formic acid from the hydrogenation of CO2. Objective: he aim is to investigate the heterogeneous catalyst systems, using solid soft base hydrotalcite supported Cu metal-based catalyst for effective and selective hydrogenation of CO2 to formic acid. Methods: The Cu –HT catalyst was synthesized and characterized by FT-IR, PXRD, SEM, TEM, XPS and BET surface area in which the precise copper content was 0.00944 mmol. The Cu-HT catalysed hydrogenation of CO2 was carried out in the autoclave. Results: The Cu-HT catalyst afforded maximum TOF of 124 h-1 under the employed reaction conditions: 100 mg catalyst, 60 °C, 60 bar total pressure of CO2/H2 (1:1, p/p) with 60 mL of mixed methanol: water (5:1, v/v) solvent, without adding any additional base or promoter and was recycled 4 times by simple filtration without compromising the formic acid yield. Formation of formic acid was observed to depend on the amount of the catalyst, partial pressures of CO2 and H2, total pressure, temperature and time. Conclusion: Cu-HT based heterogeneous catalyst was found to be efficient for selective hydrogenation of CO2 to formic acid and was effectively recycled four times after elegantly separating by simple filtration.
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Yao, Ming-Hui, David J. Smith i Abhaya K. Datye. "Observation of supported catalyst particles by high-resolution SEM". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1.08.1993): 782–83. http://dx.doi.org/10.1017/s042482010014974x.
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Supported metal particle catalysts have found wide application in the chemical industry and for environmental control. Many microscopy techniques have been employed to study these catalysts. Although scanning electron microscopy(SEM) is not commonly used, its ability to provide surface topological information as well as the ease of sample preparation and observation are positive attractions for catalysis research. Due to limited SEM resolution in the past, as well as severe charging of the insulating catalyst supports, very few studies of catalysts using SEM appear to have been reported. Recent development of in-lens specimen immersion systems and cold field emission sources of high brightness have made it possible to image specimen surfaces with secondary electrons at subnanometer resolution. Using a high resolution Hitachi S-5000 in-lens field emission SEM, we have studied Pt particles supported on TiO2 and CeO2. The purpose of this study was to evaluate relative merits and demerits of high resolution SEM for catalysis research, in particular with respect to TEM and STEM techniques.
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Ibrahim, Mohamed, Fahad A. Al-Zahrani, Francisco J. Diaz, Tareq Al-Attas, Hasan Zahir, Syed A. Ali, Mohammed Abdul Bari Siddiqui i Mohammad M. Hossain. "Experimental Investigation of Metal-Based Calixarenes as Dispersed Catalyst Precursors for Heavy Oil Hydrocracking". Catalysts 12, nr 10 (17.10.2022): 1255. http://dx.doi.org/10.3390/catal12101255.
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Slurry-phase hydrocracking utilizing metal-containing oil-soluble compounds as precursors of dispersed catalysts is an effective approach for heavy oil upgrading. We propose applying metal-based p-tert-butylcalix[6]arene (TBC[6]s) organic species as dispersed catalyst precursors to enhance catalytic hydrogenation reactions involved in the upgrading of vacuum gas oil (VGO). Co- and Ni-based TBC[6]s were synthesized and characterized by SEM-EDX, ICP, XRD, and FT-IR. The thermogravimetric and calorimetric behaviors of the synthesized complexes, which are key properties of dispersed hydrocracking catalysts, were also explored. The experimental evaluation of the synthesized catalyst precursors show that the synthesized metal-based TBC[6] catalyst precursors improved the catalytic hydrogenation reactions. A co-catalytic system was also investigated by adding a commercial, first-stage hydrocracking supported catalyst in addition to the dispersed catalysts. The naphtha yields increased from 10.7 wt.% for the supported catalyst to 11.7 wt.% and 12 wt.% after adding it along with Ni-TBC[6] and Co-TBC[6], respectively. Mixing the metal-based precursors resulted in elevated yields of liquid products due to the in situ generation of highly active Co–Ni bimetallic dispersed catalysts.
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Nugrahaningtyas, Khoirina Dwi, Wega Trisunaryanti, Triyono Triyono, Nuryono Nuryono, Dian Maruto Widjonarko, Ari Yusnani i Mulyani Mulyani. "PREPARATION AND CHARACTERIZATION THE NON-SULFIDED METAL CATALYST: Ni/USY and NiMo/USY". Indonesian Journal of Chemistry 9, nr 2 (22.06.2010): 177–83. http://dx.doi.org/10.22146/ijc.21526.
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The two-new catalysts had been prepared by using the impregnation method according to Nugrahaningtyas [6] and Li [4]. One catalyst is of Nickel (Ni), supported on Ultra Stable Zeolite Y (USY), whereas the other one is NiMo supported on same supporting agent. These new catalysts are expected to be more effective when applied on the hydrotreatment reaction in standpoint of its capabilities on removing the unwanted-heteroatom. Characterization those two types of catalysts then carried out by using the criteria of acidity, porosity and, metal content. The result shows that these non-sulfide catalysts have several good characters that supporting their usefulness in hydrotreatment-catalytic reaction. In addition, catalyst NiMo/USY - 1 performs many ideal criteria as the best functional catalyst. Keywords: Non-sulfided Catalyst, hydro-treating, preparation, characterization
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Kim, Munjeong, Juyoung Kim, Young Min Jo i Jong-Ki Jeon. "Decomposition of Hydroxylammonium Nitrate Solution Over Nanoporous CuO Supported on Honeycomb". Journal of Nanoscience and Nanotechnology 21, nr 8 (1.08.2021): 4532–36. http://dx.doi.org/10.1166/jnn.2021.19438.
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We investigated the influence of a copper loading strategy over a honeycomb structure on the catalytic performance during the decomposition of a hydroxylammonium nitrate (HAN) aqueous solution. Copper was supported on the honeycomb surface by means of a metal coating method (MC), i.e., a method of directly coating a metal, and a metal alumina coating method (MAC), i.e., a method of coating a mixture of metal and alumina. The properties of the catalysts were analyzed by N2 adsorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Cu(16.8)/honeycomb-MC catalyst showed a lower decomposition onset temperature during the decomposition of the HAN aqueous solution compared to that over the Cu(7.0)/honeycomb- MAC catalyst, an outcome ascribed to the higher copper loading and the higher dispersion of copper in the Cu(16.8)/honeycomb-MC catalyst compared to that in the other catalyst. The Cu(16.8)/honeycomb-MC catalyst was confirmed to have both excellent activity and heat resistance during the decomposition of a HAN aqueous solution.
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Jo, Yoo-Jin, Won Suk Jung i Boyoung Lim. "Review of Electro-catalysts Supported by Metal Oxides for Electrochemical Oxygen Reduction Reaction". Korean Journal of Metals and Materials 61, nr 4 (5.04.2023): 231–41. http://dx.doi.org/10.3365/kjmm.2023.61.4.231.
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Global warming and air pollution have forced greater attention to new energy sources to replace fossil fuels. Among several eco-friendly energy sources, polymer electrolyte membrane fuel cells have been increasingly investigated since they have zero emissions, high energy density, and high energy efficiency. Carbon-supported Pt catalyst is generally used for the cathodic catalyst in polymer electrolyte membrane fuel cells. However, Pt/C catalysts corrode under start-up/shut-down conditions. Pt agglomeration, separation, and loss can occur due to the carbon corrosion, which results in a rapid performance loss. Metal oxide is a promising candidate as an alternative support since it shows high stability in the high potential. Of several metal oxides, titanium oxides and tin oxides have been widely investigated. Their performance is comparable to the Pt/C catalyst, and they have shown even higher durability than the Pt/C catalyst in accelerated stress tests simulating start-up/shut-down conditions. In this paper, we summarize the development of metal oxide supports for the Pt catalyst in the five most recent years. In recent studies, the characteristics of metal oxides have been varied using new synthesis methods, annealing temperature, precursors, and dopants, which results in enhanced ORR activity and durability. Advanced metal oxides have shown high durability and exhibited acceptable performance compared to the state-of-the-art Pt/C catalysts.
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Zhuang, Huimin, Bili Chen, Wenjin Cai, Yanyan Xi, Tianxu Ye, Chuangye Wang i Xufeng Lin. "UiO-66-supported Fe catalyst: a vapour deposition preparation method and its superior catalytic performance for removal of organic pollutants in water". Royal Society Open Science 6, nr 4 (kwiecień 2019): 182047. http://dx.doi.org/10.1098/rsos.182047.
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A vapour deposition (VD) method was established for preparation of the UiO-66-supported Fe (Fe/UiO-66) catalyst, which provided the first case of the metal-organic framework (MOF)-supported Fe catalyst prepared by using the vapour-based method. The Fe loading was around 7.0–8.5 wt% under the present preparation conditions. The crystal structure of UiO-66 was not obviously influenced by the Fe loading, while the surface area significantly decreased, implicating most of the Fe components resided in the pores on UiO-66. The results for the methyl orange (MO) removal tests showed that MO in aqueous solution can be removed by UiO-66 by adsorption, and in contrast, it can be oxidized by H 2 O 2 with the catalysis of Fe/UiO-66. Further catalytic tests showed that Fe/UiO-66 was rather effective to catalyse the oxidation of benzene derivatives like aniline in water in terms of chemical oxygen demand (COD) removal efficiency. The catalytic test results for Fe/UiO-66 were compared to those of Fe/Al 2 O 3 with the same Fe loading and to the catalysts reported in the literature. This paper provides a general strategy for VD preparation of MOF-supported Fe catalyst on the one hand, and new catalysts for removing organic pollutants from water, on the other hand.
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Lee, Su-Un, You-Jin Lee, Soo-Jin Kwon, Jeong-Rang Kim i Soon-Yong Jeong. "Pt-Sn Supported on Beta Zeolite with Enhanced Activity and Stability for Propane Dehydrogenation". Catalysts 11, nr 1 (28.12.2020): 25. http://dx.doi.org/10.3390/catal11010025.
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With the growing global propylene demand, propane dehydrogenation (PDH) has attracted great attention for on-purpose propylene production. However, its industrial application is limited because catalysts suffer from rapid deactivation due to coke deposition and metal catalyst sintering. To enhance metal catalyst dispersion and coke resistance, Pt-based catalysts have been widely investigated with various porous supports. In particular, zeolite can benefit from large surface area and acid sites, which favors high metal dispersion and promoting catalytic activity. In this work, we investigated the PDH catalytic properties of Beta zeolites as a support for Pt-Sn based catalysts. In comparison with Pt-Sn supported over θ-Al2O3 and amorphous silica (Q6), Beta zeolite-supported Pt-Sn catalysts exhibited a different reaction trend, achieving the best propylene selectivity after a proper period of reaction time. The different PDH catalytic behavior over Beta zeolite-supported Pt-Sn catalysts has been attributed to their physicochemical properties and reaction mechanism. Although Pt-Sn catalyst supported over Beta zeolite with low acidity showed low Pt dispersion, it formed a relatively lower amount of coke on PDH reaction and maintained a high surface area and active Pt surfaces, resulting in enhanced stability for PDH reaction. This work can provide a better understanding of zeolite-supported Pt-Sn catalysts to improve PDH catalytic activity with high selectivity and low coke formation.
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Lei, L., X. Hu, H. P. Chu, G. Chen i P. L. Yue. "Catalytic wet air oxidation of dyeing and printing wastewater". Water Science and Technology 35, nr 4 (1.02.1997): 311–19. http://dx.doi.org/10.2166/wst.1997.0145.
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The treatment of dyeing and printing wastewater from the textile industry by oxidation was studied. The reaction was carried out in a two-litre high pressure reactor. In order to promote the oxidation of organic pollutants present in the wastewater, experiments were conducted using various catalysts including metal salts, metal oxides, and porous alumina supported metals. All catalysts tested were able to enhance the conversion of organic compounds in wastewater, shorten the reaction time, and lower the reaction temperature. The alumina supported catalyst has an advantage over other catalysts in that it can be easily separated from the treated wastewater by filtration and recycled. The conditions in preparing the catalyst supported by porous alumina were experimentally optimised.
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Saha, Subrata, Md Eaqub Ali, Azman Maamor i Wan Jeffery Basirun. "Design and Synthesis of Silica Supported Nanoporous Gold-Palladium Bimetallic Catalyst for Alkyl Benzene Oxidation". Advanced Materials Research 1109 (czerwiec 2015): 444–47. http://dx.doi.org/10.4028/www.scientific.net/amr.1109.444.
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Gold palladium (Au-Pd) bimetallic catalysts are very promising for various reactions including oxidative catalysis. Mesoporous silica supported Au-Pd catalysts have large surface area, controlled hydrophobi and file-cities and are thus highly efficient for the oxidation of alkyl benzene to selective products. Alkyl Benzene oxidation is important for the productions of drugs, perfumes, polymers, insecticides and pesticides. Unfortunately, the efficient oxidation of alkyl benzene has been remaining a challenging task due to lack of suitable catalysts. Functionalized mesoporous silica with ordered surface and uniform porosity is an exciting template for the synthesis of supported catalysts. Metal precursors could be co-impregnated on the highly ordered surface of ammine functionalized silica. This method facilitates great dispersion of the Au-Pd clusters with tiny and controlled particle size. Here, we described a two-step adsorption –reduction method along with various ratios of metal loadings for the synthesis of silica supported nanoporous Au-Pd catalyst for alkyl benzene oxidation.
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Ballaschk, Frederic, i Stefan F. Kirsch. "Oxidation of secondary alcohols using solid-supported hypervalent iodine catalysts". Green Chemistry 21, nr 21 (2019): 5896–903. http://dx.doi.org/10.1039/c9gc02605c.
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Jomhataikool, Buntita, Wachiraporn Gunpum, Wasawat Kraithong, Nawin Viriya-Empikul i Apiluck Eiad-Ua. "Fantastic Carbon Material for Nickel/Carbon Support Catalyst Reducing via Calcination Enhanced with Hydrothermal Carbonization". Materials Science Forum 872 (wrzesień 2016): 201–5. http://dx.doi.org/10.4028/www.scientific.net/msf.872.201.
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In generally, the metal catalyst which synthesis by conventional techniques is usually in metal oxide form or easily oxidize in the air thus the metal catalyst must reduce to metallic form before using. It was complex process and dangerous. In the research, Carbon material from cattail flower (CF) were used as supporter of Nickel/Carbon supported metal catalyst (Ni/C). This research were studied effect of used carbon material from CF as supporter of Ni/C and varying nickel loading. The Ni/C catalyst were prepared by hydrothermal, impregnation and calcination process. Firstly, Dried CF has been pretreat via hydrothermal process with optimized condition at 180°C for 8h. Then, the nickel solution was added to support via impregnation method by varying Ni loading from 20 to 60 wt% of supported. Finally, the sample has been pelleted into 0.5mm-Ni/C pellet and calcined at 900°C for 2h under nitrogen atmosphere. Ni/C were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), surface area and pore size distribution was determined by N2 adsorption. The result indicate that nickel particle on Ni/C were in the free metal from without reduction and well dispersed on supported surface. Particle size and surface area of Ni/C were decreases at the increase metal loading. Nickel/Carbon supported metal catalyst were ready to use and could be controlled particle size, surface area and crystallinity by metal loading.
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Hong, Ga-Ram, Kyoung-Jin Kim, Seon-Yong Ahn, Beom-Jun Kim, Ho-Ryong Park, Yeol-Lim Lee, Sang Soo Lee, Yukwon Jeon i Hyun-Seog Roh. "Sulfur-Resistant CeO2-Supported Pt Catalyst for Waste-to-Hydrogen: Effect of Catalyst Synthesis Method". Catalysts 12, nr 12 (19.12.2022): 1670. http://dx.doi.org/10.3390/catal12121670.
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To improve the sulfur tolerance of CeO2-supported Pt catalysts for water gas shift (WGS) using waste-derived synthesis gas, we investigated the effect of synthesis methods on the physicochemical properties of the catalysts. The Pt catalysts using CeO2 as a support were synthesized in various pathways (i.e., incipient wetness impregnation, sol-gel, hydrothermal, and co-precipitation methods). The prepared samples were then evaluated in the WGS reaction with 500 ppm H2S. Among the prepared catalysts, the Pt-based catalyst prepared by incipient wetness impregnation showed the highest catalytic activity and sulfur tolerance due to the standout factors such as a high oxygen-storage capacity and active metal dispersion. The active metal dispersion and oxygen-storage capacity of the catalyst showed a correlation with the catalytic performance and the sulfur tolerance.
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Safaat, Muhammad, Indri Badria Adilina i Silvester Tursiloadi. "A Review on the Hydroisomerisasion of n-Parafins over Supported Metal Catalysts". Jurnal Rekayasa Proses 15, nr 2 (30.12.2021): 141. http://dx.doi.org/10.22146/jrekpros.67587.
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Catalytic hydroisomerization of n-paraffin aims to produce branched paraffin isomers and suppress cracking reactions in the production of the low cloud point of biodiesel. The development of the type of metal and catalyst support, amount of metal loading, and reaction conditions are important to increase the catalyst activity. A high performace catalyst for hydroisomerization bears bifunctional characteristics with a high level of hydrogenation active sites and low acidity, maximizing the progress of hydroisomerization compared to the competitive cracking reaction. In addition, a catalyst support with smaller pore size can hinder large molecular structure isoparaffins to react on the acid site in the pore thus providing good selectivity for converting n-paraffin. Catalysts loaded with noble metals (Pt or Pd) showed significantly higher selectivity for hydroisomerization than non-noble transition metals such as Ni, Co, Mo and W. The reaction temperature and contact time are also important parameters in hydroisomerization of long chain paraffin, because long contact times and high temperatures tend to produce undesired byproducts of cracking. This review reports several examples of supported metal catalyst used in the hydroisomerization of long chain hydrocarbon n-paraffins under optimized reaction conditions, providing the best isomerization selectivity results with the lowest amount of byproducts. The role of various metals and their supports will be explained mainly for bifunctional catalysts.
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Hamzah, Noraini, Wan Nor Roslam Wan Isahak, Nadia Farhana Adnan, Nor Asikin Mohamad Nordin, Mohamad Bin Kassim i Mohd Ambar Yarmo. "Catalytic Activity and Physical Properties of Nanoparticles Metal Supported on Bentonite for Hydrogenolysis of Glycerol". Advanced Materials Research 364 (październik 2011): 211–16. http://dx.doi.org/10.4028/www.scientific.net/amr.364.211.
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Catalysts prepared from a variety of noble metal (Os, Ru, Pd and Au) supported on bentonite using impregnation method were studied and it found these series catalyst system gave different activity and selectivity. Among these catalysts, Os/bentonite and Ru/bentonite catalyst showed high activity in glycerol hydrogenolysis reaction at 150°C, 2.0 MPa initial hydrogen pressure for 7 hours. TEM analysis revealed that these nanometal particles catalyst have different in size and result showed that Os and Ru which have smaller average size in range 1-3 nm gave high activity which are 54.1% and 61.2% respectively. In contrast, less activity was obtained when using Pd/bentonite (29.0%) and Au/bentonite (27.8%) catalyst and TEM result showed that Pd and Au nanoparticles have large average particles size (8-10) nm. NH3-TPD analysis revealed that Ru/bentonite and Os/bentonite catalyst gave high total acidity and this behaviour contribute to high activity of the catalyst. This study revealed that size of nanoparticles and catalyst acidity play an important role in the activity and selectivity in glycerol hydrogenolysis reaction. These catalysts were also characterized by BET, XRD and XPS in order to get some physicochemical properties of the catalyst.
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Harris, Peter J. F. "The surface structure of platinum catalyst particles". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 4 (sierpień 1990): 296–97. http://dx.doi.org/10.1017/s0424820100174618.
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For many metal-catalysed reactions, activity and selectivity depend strongly on the structure of the metal surface. However, surprisingly little is known about the surface structures of supported ultrafine metal particles of the type used in practical catalysts. Transmission electron microscopy can play an important role in this area, and is beginning to produce results which could have a major impact on our understanding of processes such as catalyst poisoning and promotion.In this study, which builds on previous work, the effect of various heat-treatments on the shapes and surface structures of alumina-supported platinum particles has been investigated using both conventional bright field TEM and high-resolution imaging. It has been found, for example, that heating in hydrogen tends to produce almost spherical particles with little faceting, as shown in Figure 1. Heating in sulphur-containing atmospheres, on the other hand, produces sharp (100) faceting so that the particles often display square or rectangular profiles, as shown in Figure 2. It is well known that sulphur poisoning can produce changes in catalytic selectivity without deactivating the catalyst completely.
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Yang, Hui Min, Xiao Hui Guo, Chun Hua Yuan, Jin Yan Liu i Wen Xiu He. "One-Pot Preparation of Carbon Immobilized Nano-Metal Catalysts from Biomass". Materials Science Forum 932 (wrzesień 2018): 119–23. http://dx.doi.org/10.4028/www.scientific.net/msf.932.119.
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Preparation of carbon supported nanometal catalysts were realized through the carbonization of metal precursor doped carboxymethyl cellulose under nitrogen condition. This carbon supported nanometal catalyst exhibited good activity in the reductive amination of amine. The results suggested a promising one-pot route based on economical and sustainable biomass towards the development of value carbon materials as effective catalyst for C-N bond synthesis reaction.
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Shao, Jiaming, Yunchu Zhai, Luyang Zhang, Li Xiang i Fawei Lin. "Low-Temperature Catalytic Ozonation of Multitype VOCs over Zeolite-Supported Catalysts". International Journal of Environmental Research and Public Health 19, nr 21 (4.11.2022): 14515. http://dx.doi.org/10.3390/ijerph192114515.
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Volatile organic compounds (VOCs) are an important source of air pollution, harmful to human health and the environment, and important precursors of secondary organic aerosols, O3 and photochemical smog. This study focused on the low-temperature catalytic oxidation and degradation of benzene, dichloroethane, methanethiol, methanol and methylamine by ozone. Benzene was used as a model compound, and a molecular sieve was selected as a catalyst carrier to prepare a series of supported active metal catalysts by impregnation. The effects of ozone on the catalytic oxidation of VOCs and catalysts’ activity were studied. Taking benzene as a model compound, low-temperature ozone catalytic oxidation was conducted to explore the influence of the catalyst carrier, the active metal and the precious metal Pt on the catalytic degradation of benzene. The optimal catalyst appeared to be 0.75%Pt–10%Fe/HZSM(200). The catalytic activity and formation of the by-products methylamine, methanethiol, methanol, dichloroethane and benzene over 0.75%Pt–10%Fe/HZSM(200) were investigated. The structure, oxygen vacancy, surface properties and surface acidity of the catalysts were investigated. XRD, TEM, XPS, H2-TPR, EPR, CO2-TPD, BET, C6H6-TPD and Py-IR were combined to establish the correlation between the surface properties of the catalysts and the degradation activity.
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Mardwita, Mardwita, Eka Sri Yusmartini i Nidya Wisudawati. "Effects of Calcination Temperatures on The Catalytic Activities of Alumina Supported Cobalt and Chromium Catalysts". Bulletin of Chemical Reaction Engineering & Catalysis 14, nr 3 (1.12.2019): 654. http://dx.doi.org/10.9767/bcrec.14.3.4673.654-659.
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Catalysts properties are important for catalytic reactions. The interaction between support and metal in a catalyst is resulted from catalyst preparation. In this study, gamma-alumina (Al2O3) supported cobalt (Co) and chromium (Cr) catalysts were prepared by impregnation method and calcined at two different temperatures, they are 400 °C for 4 hours and 800 °C for 4 hours. The resulted catalysts contained 10 wt.% of metal and denoted as Co/Al2O3(400), Co/Al2O33(800), Cr/Al2O3(400), and Cr/Al2O3(800) catalysts. The surface and state of the catalysts were examined by using x-ray diffraction (XRD), x-ray photoelectron spectrometer (XPS) and transmission electron microscopy (TEM). The XRD result reveals that strong interaction between Co and Al2O3 due to a formation of higher cobalt oxide. The XRD result further indicates aggregation and strong support metal interaction between Co and Al2O3 during calcination. On the other hand, TEM result showed that large Co particle was observed on Al2O3. The Cr/Al2O3 catalysts were characterized by using XPS. The XPS results showed that Cr/Al2O3(800) catalyst was dominated by Cr6+ species at binding energy 579.04 eV, indicating high dispersion of Cr on Al2O3. Moreover, Cr metal particle was not observed on XRD and TEM image. All the characterization results provide information that the impregnated metal on Al2O3 showed different properties. Co metal particle tends to be more oxidized and formed large particle, however it was not observed on Cr metal particle. Copyright © 2019 BCREC Group. All rights reserved
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Stanchovska, Silva, Georgy Ivanov, Sonya Harizanova, Krasimir Tenchev, Ekaterina Zhecheva, Anton Naydenov i Radostina Stoyanova. "New Insight into the Interplay of Method of Deposition, Chemical State of Pd, Oxygen Storage Capability and Catalytic Activity of Pd-Containing Perovskite Catalysts for Combustion of Methane". Catalysts 11, nr 11 (18.11.2021): 1399. http://dx.doi.org/10.3390/catal11111399.
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Elaboration of Pd-supported catalysts for catalytic combustion is, nowadays, considered as an imperative task to reduce the emissions of methane. This study provides new insight into the method of deposition, chemical state of Pd and oxygen storage capability of transition metal ions and their effects on the catalytic reactivity of supported catalysts for the combustion of methane. The catalyst with nominal composition La(Co0.8Ni0.1Fe0.1)0.85Pd0.15O3 was supported on SiO2-modified/γ-alumina using two synthetic procedures: (i) aerosol assisted chemical vapor deposition (U-AACVD) and (ii) wet impregnation (Imp). A comparative analysis shows that a higher catalytic activity is established for supported catalyst obtained by wet impregnation, where the PdO-like phase is well dispersed and the transition metal ions display a high oxygen storage capability. The reaction pathway over both catalysts proceeds most probably through Mars–van Krevelen mechanism. The supported catalysts are thermally stable when they are aged at 505 °C for 120 h in air containing 1.2 vol.% water vapor. Furthermore, the experimentally obtained data on La(Co0.8Ni0.1Fe0.1)0.85Pd0.15O3—based catalyst, supported on monolithic substrate VDM®Aluchrom Y Hf are simulated by using a two-dimensional heterogeneous model for monolithic reactor in order to predict the performance of an industrial catalytic reactor for abatement of methane emissions.
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Silas, Kiman, Wan Azlina Wan Ab Karim Ghani, Thomas Shean Yaw Choong i Umer Rashid. "Monolith Metal-Oxide-Supported Catalysts: Sorbent for Environmental Application". Catalysts 10, nr 9 (4.09.2020): 1018. http://dx.doi.org/10.3390/catal10091018.
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The emission of untreated environmental harmful gases such as sulfur and nitrogen oxide (SOx and NOx) emissions is considered old fashioned, since industries are compelled by governments and legislations to meet the minimum threshold before emitting such substances into the atmosphere. Numerous research has been done and is ongoing to come up with both cost-effective equipment and regenerable catalysts that are adsorbent—or with enhanced sorption capacity—and with safer disposal methods. This work presents the general idea of a monolith/catalyst for environmental application and the technicality for improving the surface area for fast and efficient adsorption–desorption reactions. The chemical reactions, adsorption kinetics, and other properties, including deactivation, regeneration, and the disposal of a catalyst in view of environmental application, are extensively discussed.
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Legrouri, A. "Preparation and characterisation of vanadium pentoxide supported rhodium catalyst". Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 946–47. http://dx.doi.org/10.1017/s042482010010679x.
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The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.
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Rusanen, Annu, Riikka Kupila, Katja Lappalainen, Johanna Kärkkäinen, Tao Hu i Ulla Lassi. "Conversion of Xylose to Furfural over Lignin-Based Activated Carbon-Supported Iron Catalysts". Catalysts 10, nr 8 (22.07.2020): 821. http://dx.doi.org/10.3390/catal10080821.
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In this study, conversion of xylose to furfural was studied using lignin-based activated carbon-supported iron catalysts. First, three activated carbon supports were prepared from hydrolysis lignin with different activation methods. The supports were modified with different metal precursors and metal concentrations into five iron catalysts. The prepared catalysts were studied in furfural production from xylose using different reaction temperatures and times. The best results were achieved with a 4 wt% iron-containing catalyst, 5Fe-ACs, which produced a 57% furfural yield, 92% xylose conversion and 65% reaction selectivity at 170 °C in 3 h. The amount of Fe in 5Fe-ACs was only 3.6 µmol and using this amount of homogeneous FeCl3 as a catalyst, reduced the furfural yield, xylose conversion and selectivity. Good catalytic activity of 5Fe-ACs could be associated with iron oxide and hydroxyl groups on the catalyst surface. Based on the recycling experiments, the prepared catalyst needs some improvements to increase its stability but it is a feasible alternative to homogeneous FeCl3.
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Yang, Haobo, Jichao Li, Hao Yu, Feng Peng i Hongjuan Wang. "Metal-Foam-Supported Pd/Al2O3 Catalysts for Catalytic Combustion of Methane: Effect of Interaction between Support and Catalyst". International Journal of Chemical Reactor Engineering 13, nr 1 (1.03.2015): 83–93. http://dx.doi.org/10.1515/ijcre-2014-0009.
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Abstract Structured Pd/Al2O3 catalysts were fabricated by impregnating Pd onto Ni and Cu foams coated with Al2O3 layers. By testing the adhesion stability and catalytic activity in the combustion of methane, the superior performance of Ni-foam-supported Pd/Al2O3 catalyst was demonstrated, to its counterpart powder catalysts. The resultant structured catalysts enable the fabrication of lamellar microreactor systems. It is found that the metal foams influence the activity of catalyst layer, due to the diffusive penetration of metallic atoms into catalysts from metal foams. The Ni foam is beneficial for enhancing the activity of Pd/Al2O3 catalyst, while the Cu foam plays a negative role. The investigation to the model powder catalysts doped with Ni and Cu verified the modification of Ni and Cu to the physicochemical properties of Pd/Al2O3 catalyst, thereby the catalytic performances. Thus, it can be expected that the performance of structured catalysts may be improved by rationally designing and selecting proper supports.
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Hamzah, Noraini, Aznira Alias, Wan Zurina Samad, Mohamad Bin Kassim i Mohd Ambar Yarmo. "Effect of Ruthenium Metal Precursors Supported on Bentonite in Hydrogenolysis Glycerol". Advanced Materials Research 173 (grudzień 2010): 134–39. http://dx.doi.org/10.4028/www.scientific.net/amr.173.134.
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Various ruthenium precursors (Ru= RuCl3, Ru2 = Ru(acac)3, Ru3 = Ru3(CO)12) supported on bentonite were prepared by conventional impregnation method. Their catalytic performances were evaluated in the hydrogenolysis of glycerol using autoclave Parr reactor under mild reaction conditions of 150°C, hydrogen pressure 30 bar for 7 hours. Among the studied catalyst, 5% Ru/bentonite catalyst prepared from Ru and Ru3 precursor exhibited higher activity which are 79.6% and 72.5% respectively. In contrast, Ru2/bentonite prepared from Ru(acac)3 precusor gave lowest activity (41.8%). In term of selectivity to 1,2-propanediol, Ru2 and Ru3 precusor gave higher selectivity (67.0% and 66.9%) compared to Ru precursor (50.6%). These results indicated that metal precursor plays an important role on activity and selectivity of the catalyst in hydrogenolysis reaction. The catalysts were characterized by XRD, XPS, BET, FESEM-EDX and TEM, and the reasons for the high performances of the catalyst were also discussed.
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Yu, Jian Xiang, i Tai Qi Liu. "Preparation of Chitosan Grafting Acrylic Acid Supported Palladium Fibrous Catalyst and its Application in Hydrogenation". Materials Science Forum 620-622 (kwiecień 2009): 537–40. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.537.
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Chitosan grafting acrylic copolymer (CTS-g-AA) supported Nano palladium catalyst was obtained in this paper. Chitosan grafting acrylic copolymer (CTS-g-AA) was prepared firstly and palladium was supported on CTS-g-AA; then nano fibrous catalyst was gained via electrospinning technique. The title catalysts were characterized by TEM, SEM and IR, the diameter of nanofiber was about 70~200 nm, the size of metal particles were in a range of 10~40 nm, and palladium particles dispersed on nanofibers homogeneously. The catalyst was applied to catalyze α-octene hydrogenation in normal temperature and pressure. The results showed that the conversion of α-octene was 99%, and the yield of octane was 65% by double-metal catalyst.
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Targos, W. "A microscopist's view of catalysis". Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 396–97. http://dx.doi.org/10.1017/s042482010013835x.
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Analytical electron microscopy, AEM, has provided valuable information on the structure, composition, location and size of metal clusters and/or crystallites supported on amorphous or crystalline metal oxide materials. Although this information is vital to the understanding of how a catalyst functions, the catalytic reaction is usually more complex. Many variables must be taken into account to evaluate properly a catalyst. Improper selection of process variables can make a good catalyst perform poorly. Consequently, focusing on specific metal site properties may not always be the appropriate direction to take when evaluating a supported metals catalyst problem.To help the microscopist appreciate the complexity of the problem, the following examples were chosen to illustrate this point. Reforming catalysis involves a complex set of reactions to convert naphtha feed to high octane gasoline. The catalyst is comprised of highly dispersed Pt on a high surface area alumina with Cl. The catalyst is dual functional requiring both metal site activity for dehydrogenation and acidity for isomerization and cyclization.
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Schmitz, Andrew D., Darrell P. Eyman i Kenneth C. Moore. "Scanning Electron Microscopy of a supported molten salt CuC1-KCl/SiO2 catalyst". Proceedings, annual meeting, Electron Microscopy Society of America 48, nr 4 (sierpień 1990): 286–87. http://dx.doi.org/10.1017/s0424820100174564.
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Carbon monoxide hydrogenation reactions catalyzed by heterogeneous catalysts are of significant industrial importance. Most methanol synthesis catalysts contain copper in synergism with ZnO and other metal oxide components. The chemical constitution and physical form of the copper phase in the working alcohol synthesis catalyst has been the subject of considerable concern. Recent NMR and x-ray, spectroscopic and microscopic investigation of alkali metal-promoted copper catalysts confirm earlier reports that the copper phase in methanol synthesis catalysts is a mixture of Cu(O) and Cu(I). Stabilization of a dispersion of Cu(I) is imperative for high activity.
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Selpiana, Selpiana, David Bahrin, Muhammad Ridho Habibie i Faras Saskia Samara. "Preparation and Characterization of Catalyst Zn/Al2O3 Catalyst Using Dry and Wet Impregnation Method". Indonesian Journal of Fundamental and Applied Chemistry 8, nr 1 (25.02.2023): 25–33. http://dx.doi.org/10.24845/ijfac.v8.i1.25.
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Metal supported catalysts are used in many catalytic cracking processes. Experiments have shown that the increasing of metal loaded within the catalyst support may affected the increasing of cracking process conversion and selectivity. Therefore, a fundamental understanding of increasing the metal loaded is needed. In this study, Zinc on Alumina supported catalyst was prepared using the dry and wet impregnation methods to obtain the best amount of Zn metal content in Al2O3 as catalyst support with good characteristics for catalytic cracking. The prepared precursor solution in wet impregnation method was varied in concentration. While the dry impregnation method was varied in drying temperature. The Atomic Absorption Spectroscopy test results the metal content of Zn on the variation of precursor solution concentration on 0,5 M; 2,5 M; 4,5 M are 1,06%; 9,65%; 15,91% and in the variation of the drying temperature at 25ºC, 50ºC, and 80ºC respectively are 18,32%; 12,48%; and 39,07%. Characteristics analysis through X-Ray Diffraction, Brunauer-Emmet-Teller, and Scanning Electron Microscopy tests have also been carried out on samples with the highest metal content of 39,07% and samples with the lowest metal content of 1,06%.
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Takabatake, Moe, i Ken Motokura. "Montmorillonite-based heterogeneous catalysts for efficient organic reactions". Nano Express 3, nr 1 (1.03.2022): 014004. http://dx.doi.org/10.1088/2632-959x/ac5ac3.
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Abstract In this review, we give a brief overview of recently developed montmorillonite-based heterogeneous catalysts used for efficient organic reactions. Cation-exchanged montmorillonite catalysts, metal catalysts supported on montmorillonite, and an interlayer design used for selective catalysis are introduced and discussed. In traditional syntheses, homogeneous acids and metal salts were used as catalysts, but the difficulty in separation of catalysts from products was a bottleneck when considering industrialization. The use of solid heterogeneous catalysts is one of the major solutions to overcome this problem. Montmorillonite can be used as a heterogeneous catalyst and/or catalyst support. This clay material exhibits strong acidity and a stabilizing effect on active species, such as metal nanoparticles, due to its unique layered structure. These advantages have led to the development of montmorillonite-based heterogeneous catalysts. Acidic montmorillonite, such as proton-exchanged montmorillonite, exhibits a high catalytic activity for the activation of electrophiles, such as alcohols, alkenes, and even alkanes. The montmorillonite interlayer/surface also functions as a good support for various metal species used for oxidation and carbon-carbon bond forming reactions. The use of an interlayer structure enables selective reactions and the stabilization of catalytically active species.