Relevant bibliographies by topics / Zeolites as catalysts

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Academic literature on the topic 'Zeolites as catalysts'

Author: Grafiati
Published: 4 June 2021
Last updated: 3 February 2022

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Journal articles on the topic "Zeolites as catalysts"

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Peng, Peng, Xiong-Hou Gao, Zi-Feng Yan, and Svetlana Mintova. "Diffusion and catalyst efficiency in hierarchical zeolite catalysts." National Science Review 7, no. 11 (August 21, 2020): 1726–42. http://dx.doi.org/10.1093/nsr/nwaa184.

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Abstract The preparation of hierarchical zeolites with reduced diffusion limitation and enhanced catalyst efficiency has become a vital focus in the field of zeolites and porous materials chemistry within the past decades. This review will focus on the diffusion and catalyst efficiency of hierarchical zeolites and industrial catalysts. The benefits of diffusion and catalyst efficiency at two levels of hierarchies (zeolitic component level and industrial catalyst level) from a chemical reaction engineering point of view will be analysed. At zeolitic component level, three types of mesopores based on the strategies applied toward enhancing the catalyst effectiveness factor are presented: (i) ‘functional mesopores’ (raising effective diffusivity); (ii) ‘auxiliary mesopores’ (decreasing diffusion length); and (iii) ‘integrated mesopores’ (a combination thereof). At industrial catalyst level, location and interconnectivity among the constitutive components are revealed. The hierarchical pore interconnectivity in multi-component zeolite based industrial catalysts is exemplified by fluid catalytic cracking and bi-functional hydroisomerization catalysts. The rational design of industrial zeolite catalysts at both hierarchical zeolitic component and catalyst body levels can be fully comprehended using the advanced in situ and/or operando spectroscopic, microscopic and diffraction techniques.
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Erofeev, Vladimir I., Sofiya N. Dzhalilova, Mikhail V. Erofeev, Vasilii S. Ripenko, and Vladimir P. Reschetilowski. "Conversion of the Propane–Butane Fraction into Arenes on MFI Zeolites Modified by Zinc Oxide and Activated by Low-Temperature Plasma." Molecules 25, no. 11 (June 11, 2020): 2704. http://dx.doi.org/10.3390/molecules25112704.

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The effect of modification of MFI zeolite 1–5 wt.% ZnO activated by plasma on acid and catalytic properties in the conversion of the propane–butane fraction into arenes was investigated. The high-silica zeolites with silicate module 45 were synthesized from alkaline alumina–silica gels in the presence of an ‘X-oil’ organic structure-forming additive. The modification of the zeolite with zinc was carried out by impregnating the zeolite granules in the H-form with an aqueous solution of Zn(NO3)2. The obtained zeolites were characterized by X-ray phase analysis and IR spectroscopy. It is shown that the synthesized zeolites belong to the high-silica MFI zeolites. The study of microporous zeolite-containing catalysts during the conversion of C3-C4 alkanes to aromatic hydrocarbons made it possible to establish that the highest yield of aromatic hydrocarbons is observed on zeolite catalysts modified with 1 and 3% ZnO and amount to 63.7 and 64.4% at 600 °C, respectively, which is 7.7–8.4% more than on the original zeolite. The preliminary activation of microporous zeolites modified with 1–5% ZnO and plasma leads to an increase in the yield of aromatic hydrocarbons from the propane–butane fraction; the maximum yield of arenes is observed in zeolite catalysts modified with 1 and 3% ZnO and activated by plasma, amounting to 64.9 and 65.5% at 600 °C, respectively, which is 8.9–9.5% more than on the initial zeolite. The activity of the zeolite catalysts modified by ZnO and activated by plasma show good agreement with their acid properties. Activation of the zeolites modified by 1 and 3% ZnO and plasma leads to an increase in the concentration of the weak acid sites of the catalyst to 707 and 764 mmol/g in comparison with plasma-inactivated 1 and 3% ZnO/ZKE-XM catalysts at 626 and 572 mmol/g, respectively.
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Machado, Ana Vera, Isabel Neves, Gabriela Botelho, and P. Rebelo. "Thermogravimetric Study of Polyethylene Catalytic Degradation by Zeolites." Materials Science Forum 514-516 (May 2006): 901–4. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.901.

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Commercial samples of high density polyethylene were decomposed over faujasites (FAU) type zeolites (Y-type) using thermal gravimetric analysis (TGA). The catalytic activity and behavior of the FAU-zeolites catalysts were determined. It was found that the degradation temperature of polymer strongly depends on the catalytic acidity of the zeolites. HY zeolite was identified as the most active catalyst due to its strong acidity. The results showed that the activation energy decrease with the amount of catalyst added.
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Gao, Feng. "Fe-Exchanged Small-Pore Zeolites as Ammonia Selective Catalytic Reduction (NH3-SCR) Catalysts." Catalysts 10, no. 11 (November 14, 2020): 1324. http://dx.doi.org/10.3390/catal10111324.

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Cu-exchanged small-pore zeolites have been extensively studied in the past decade as state-of-the-art selective catalytic reduction (SCR) catalysts for diesel engine exhaust NOx abatement for the transportation industry. During this time, Fe-exchanged small-pore zeolites, e.g., Fe/SSZ-13, Fe/SAPO-34, Fe/SSZ-39 and high-silica Fe/LTA, have also been investigated but much less extensively. In comparison to their Cu-exchanged counterparts, such Fe/zeolite catalysts display inferior low-temperature activities, but improved stability and high-temperature SCR selectivities. Such characteristics entitle these catalysts to be considered as key components of highly efficient emission control systems to improve the overall catalyst performance. In this short review, recent studies on Fe-exchanged small-pore zeolite SCR catalysts are summarized, including (1) the synthesis of small-pore Fe/zeolites; (2) nature of the SCR active Fe species in these catalysts as determined by experimental and theoretical approaches, including Fe species transformation during hydrothermal aging; (3) SCR reactions and structure-function correlations; and (4) a few aspects on industrial applications.
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Marosz, Monika, Bogdan Samojeden, Andrzej Kowalczyk, Małgorzata Rutkowska, Monika Motak, Urbano Díaz, Antonio E. Palomares, and Lucjan Chmielarz. "MCM-22, MCM-36, and ITQ-2 Zeolites with Different Si/Al Molar Ratios as Effective Catalysts of Methanol and Ethanol Dehydration." Materials 13, no. 10 (May 22, 2020): 2399. http://dx.doi.org/10.3390/ma13102399.

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MCM-22, MCM-36, and ITQ-2 zeolites with the intended Si/Al molar ratios of 15, 25, and 50 were synthetized and tested as catalysts for dehydration of methanol to dimethyl ether and dehydration of ethanol to diethyl ether and ethylene. The surface concentration of acid sites was regulated by the synthesis of zeolite precursors with different aluminum content in the zeolite framework, while the influence of porous structure on the overall efficiency of alcohol conversion was analyzed by application of zeolitic materials with different types of porosity—microporous MCM-22 as well as microporous-mesoporous MCM-36 and ITQ-2. The zeolitic samples were characterized with respect to their: chemical composition (ICP-OES), structure (XRD, FT-IR), texture (N2 sorption), and surface acidity (NH3-TPD). Comparison of the catalytic activity of the studied zeolitic catalysts with other reported catalytic systems, including zeolites with the similar Si/Al ratio as well as γ-Al2O3 (one of the commercial catalysts for methanol dehydration), shows a great potential of MCM-22, MCM-36, and ITQ-2 in the reactions of alcohols dehydration.
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Santoso, Aman, Ida Bagus S. Sumari, Novia Nina Safitri, Anugrah Ricky Wijaya, and Daratu Eviana Kusuma Putri. "Activation of Zeolite from Malang as Catalyst for Plastic Waste Conversion to Fuel." Key Engineering Materials 851 (July 2020): 212–19. http://dx.doi.org/10.4028/www.scientific.net/kem.851.212.

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Plastic pollution is an environmental problem that has not resolved until now. Pyrolysis is able to be a solution to reduce plastic waste. The use of catalysts will reduce heating temperatures, speed up processing time, and increase product yield. Natural zeolite has the potency as a catalyst in pyrolysis process due to its micropore structure, high acidity and thermal stability. The purpose of this research is to determine the effect of active zeolite catalyst on the polypropylene pyrolysis. The main process of this study is pyrolysis of polypropylene (PP) plastic waste without catalysts and with natural zeolite catalysts which were non-activated and activated. Natural zeolites were activated by HF, HCl and NH4Cl. The well result of this research is represented by the yield, viscosity, calorific value, FTIR and GC-MS analysis. Based on the results of diffractogram analysis, natural zeolites catalyst in this study is included in modernite minerals crystalline. The ratio of Si/Al in zeolite before activation was 7.07 and the acidity was 0.697 g/mmol. After the activation process, the ratio of Si/Al and zeolite acidity increased by 62.181% and 43.84%. The use of active natural zeolite catalysts in pyrolysis PP could reduce the total reaction time by 57.14%. Pyrolysis products with active zeolite catalyst compared to without catalysts had clearer color and higher heating value, compared to pirolysis without catalyst. Based on function group analysis with FTIR, the mixture of hydrolyzed compounds containing successive functional groups are-C-H (alkanes), double bond of C=C, hydroxyl-OH group which can be determined as phenol (ArOH), alcohol (ROH), and carboxylic acid (RCOOH). The GC-MS analysis showed that pyrolysis products are composed of a mixture of alkanes, cycloalkanes, alkenes, carboxylic acids with aromatic rings, and ketones. The pyrolysis products without catalysts consist of 5-11 (C5-C11) carbon atoms, whereas the range of carbon atoms of pyrolysis products with active zeolite catalysts was 6-24 (C6-C24).
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Jeong, Sangmin, Ki-Joon Jeon, Young-Kwon Park, Byung-Joo Kim, Kyong-Hwan Chung, and Sang-Chul Jung. "Catalytic Properties of Microporous Zeolite Catalysts in Synthesis of Isosorbide from Sorbitol by Dehydration." Catalysts 10, no. 2 (January 23, 2020): 148. http://dx.doi.org/10.3390/catal10020148.

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As bisphenol A has been found to cause hormonal disturbances, the natural biomaterial isosorbide is emerging as a substitute. In this study, a method for isosorbide synthesis from sorbitol was proposed by dehydration under high temperature and high pressure reaction. Microporous zeolites and Amberlyst 35 solid acids with various acid strengths and pore characteristics were applied as catalysts. In the synthesis of isosorbide from sorbitol, the acidity of the catalyst was the main factor. MOR and MFI zeolite catalysts with high acid strength and small pore size showed low conversion of sorbitol and low yield of isosorbide. On the other hand, the conversion of sorbitol was high in BEA zeolite with moderate acid strength. Amberlyst 35 solid acid catalysts showed a relatively high conversion of sorbitol, but low yield of isosorbide. The Amberlyst 35 solid acid catalyst without micropores did not show any inhibitory effects on the production of by-products. However, in the BEA zeolite catalyst, which has a relatively large pore structure compared with the MOR and MFI zeolites, the formation of by-products was suppressed in the pores, thereby improving the yield of isosorbide.
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Lao-Ubol, Supranee, Phunthinee Somwongsa, Pracha Laoauyporn, Pasinee Panith, Siriporn Larpkiattaworn, and Shih Yuan Chen. "Effect of Silica Base Catalyst on Transformation of Methanol to Hydrocarbon." Key Engineering Materials 751 (August 2017): 512–17. http://dx.doi.org/10.4028/www.scientific.net/kem.751.512.

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Five different types of silica catalyst (SBA-15, SBA-15-PO3H2, and three different Si/Al ratio of commercial zeolites (30, 80 and 280) were used to study the transformation of methanol to hydrocarbon (MTH). The aim of this study was to investigate the effect of pore diameter and acidity in the structure of silica catalysts on the process performances in terms of methanol conversion and hydrocarbon selectivity. The mesoporous silica catalysts were prepared by co-condensation method. The catalysts samples were characterized by GC-MS, XRD, BET, and NH3-TPD techniques. The catalytic performance of synthesized and commercial catalysts for MTH process was evaluated using a homemade fixed bed reactor at temperature (300°C). It was found that the liquid hydrocarbon product provided by zeolite catalysts is aromatic hydrocarbons-rich. High Si/Al zeolites with larger pore size lead to higher selectivity and yield to paraffins (C1-C7). In contrast to commercial zeolite catalyst, SBA-15 and its modification with phosphorus species showed no conversion under studied condition. These results indicate that both pore diameter and acidity influence the product distribution in methanol to hydrocarbon process.
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Putluru, Siva Sankar Reddy, Leonhard Schill, Anker Degn Jensen, and Rasmus S. N. Fehrmann. "Selective Catalytic Reduction of NOx with NH3 on Cu-, Fe-, and Mn-Zeolites Prepared by Impregnation: Comparison of Activity and Hydrothermal Stability." Journal of Chemistry 2018 (December 10, 2018): 1–11. http://dx.doi.org/10.1155/2018/8614747.

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Cu-, Fe-, and Mn-zeolite (SSZ-13, ZSM-5, and BEA) catalysts have been prepared by incipient wetness impregnation and characterized by N2 physisorption, H2-TPR, NH3-TPD, and XPS methods. Both metal and zeolite support influence the deNOx activity and hydrothermal stability. Cu-zeolites and Mn-zeolites showed medium temperature activity, and Fe zeolites showed high temperature activity. Among all the catalysts, Cu-SSZ-13 and Fe-BEA are the most promising hydrothermally resistant catalysts. Fresh and hydrothermally treated catalysts were further examined to investigate the acidic and redox properties and the zeolite surface composition. Increased total acidity after metal impregnation and loss of acidity due to hydrothermal treatment were observed in all the catalysts. Hydrothermal treatment resulted in migration of metal or in strong metal support interations, whereby changes in reduction patterns are observed.
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Juzsakova, Tatjána, Noor Al-Jammal, Igor Cretescu, Viktor Sebestyén, Cuong Le Phuoc, Endre Domokos, Ákos Rédey, and Catalina Stan. "Case Studies for Clean Technology Development in the Chemical Industry Using Zeolite Based Catalysts." Minerals 8, no. 10 (October 17, 2018): 462. http://dx.doi.org/10.3390/min8100462.

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This paper deals with the practical implementation of cleaner technologies in the chemical industry, using two case studies as an illustration. The first case study deals with the removal of NOx and N2O gases over an iron-doped ZSM-5 catalyst developed for tail gas treatment in nitric acid manufacturing. The aim for this case study was to investigate the efficiency of the zeolitic catalyst in the DeNOx process and to compare its catalytic activity with the conventional vanadia-titania. By the experiments carried out, it can be concluded that the new technological developments could significantly contribute to a decrease in environmental pollution. The second case study focuses on zeolite-based catalysts prepared from zeolitic tuff by the impregnation method, for biodiesel production from waste sunflower vegetable oil. The effects of operating and processing variables such as reaction temperature and time were investigated. The results showed that the highest biodiesel yield was 96.7% at an 11.5 MeOH/oil molar ratio, in the presence of 6.4 wt % catalyst at a 50 °C reaction temperature and reaction time of 2 h. The properties of the biodiesel that was produced, such as the viscosity, meet the required specifications of standard JUS EN14214. The common feature of the two different case studies is that both technologies use zeolite catalysts, namely naturally-occurring zeolitic tuff and synthetic ZSM type zeolite catalyst. The examples shown emphasize the importance of the zeolites in clean chemical technologies, which contribute to the protection of the environment.
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Dissertations / Theses on the topic "Zeolites as catalysts"

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Sonqishe, Thantaswa Millecent. "Treatment of brines using commercial zeolites and zeolites synthesized from fly ash derivative." Thesis, University of the Western Cape, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6127_1297842299.

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The objectives of this project was to ameroliate two waste materials, namely Acid Mine Drainage and Fly Ash and recover the solid residues for conversion into an adsorbent to treat brine. The solid residues were then converted into zeolite P through low temperature hydrothermal treatment. The adsorption capacity of the solid residues, zeolite P derived from the solid residues was compared to the commercial zeolite Y and fresh Arnot fly ash. The quality of the resulting water was assessed using different analytical methods before the reaction with adsorbents and after the reaction and a comparison was done based on the removal efficiency of elements Zeolite P from solid residues was successfully synthesized as confirmed by XRD, BET and FTIR. Brine treatment with fly ash, solid residues, zeolite P and commercial zeolite Y adsorbents was done concentration on the following major elements Na, K, Mg, Ca and Si. Zeolite P had higher or similar removal efficiency that the commercial zeolite Y for the following elements K, Ca and Mg. Fly ash is the only adsorbent that managed to reduce the concentration of Na in brine and also had a good removal efficiency of Mg. Si leached out of all the adsorbents which could be ascribed to Si being the major component of these adsorbents which could indicate some dissolution of these adsorbents under the conditions tested. Overall, zeolite P did not completely remove the major elements, especially for Na, but did result in a cleaner waste stream which would improve brine processing.

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Huang, Wei. "Selective hydrogenation on zeolite-supported bimetallic catalysts." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.90 Mb., p. 76, 2005. http://proquest.umi.com/pqdlink?did=1037889271&Fmt=7&clientId=8331&RQT=309&VName=PQD.

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Uçar, Şule Yılmaz Selahattin. "Investigation Of Catalytic Activity And Selectivity Of Pd and Ni Loaded Clinoptilolite Rich Natural Zeolite For Citral Hydrogenation/." [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000122.doc.

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Monama, Winnie. "Hierarchical zeolites: novel supports for hydrocracking catalysts." Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/1565.

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Thesis (M. Sc. (Chemistry)) -- University of Limpopo, 2016
In this study, the use of synthetic hierarchical MFI zeolites as supports for palladium hydrocracking catalysts was investigated. Hierarchical zeolites were synthesised through two different routes, viz., (i) the indirect and (ii) direct routes. In (i) pristine ZSM-5 zeolites with different SiO2/Al2O3 ratios (SARs) were synthesised hydrothermally using tetrapropylammonium bromide as structure-directing agent (SDA), followed by a brief desilication of its calcined form in 0.2 M NaOH solution at 65 °C for 0.5 h. Procedure (ii) involved prior synthesis of three polyquaternary ammonium surfactants (containing 2 - 4 ammonium centres), followed by their use as SDAs in the hydrothermal synthesis of hierarchical MFI zeolites. The resulting materials were characterised by XRD, FT-IR, SEM and N2 adsorption isotherms (including BET surface area measurements). Successful synthesis of different classes of the hierarchical MFI zeolites was confirmed by XRD patterns, while successful synthesis of polyquaternary ammonium surfactants was confirmed by both their 1H NMR spectra and their ability to direct the MFI structure. On the basis of IR, peak intensities in the OH region between 3500 and 3800 cm-1, the surfactant-templated zeolites were inferred to be more acidic than zeolites prepared through the desilication route. Significant changes in crystal morphology were observed upon desilication of ZSM-5(50), while the ZSM-5(77) and ZSM-5(100) retained their agglomerated morphology upon a similar treatment. The micrograph pristine of ZSM-5(50) showed a predominant morphology of large and small spheroids, together with some ill-defined cubic shapes. After desilication, the zeolite did not retain the original morphology entirely, showing hexagonal prismatic crystals with twinning occurring in other areas and large spheroids “hatching” to reveal their contents upon treatment. Desilicated zeolites exhibited improved textural properties (i.e., increased SBET, pore volumes and pore diameters) and minor structural readjustments compared to their pristine counterparts. Textural properties of surfactant-templated zeolites were superior to those of desilicated zeolites, and improved with increasing number of quaternary ammonium centres in the surfactant template. These materials were generally more crystalline than the conventional zeolites. Hydrocracking catalysts containing 0.9 wt.% Pd loading on different MFI supports were prepared by the incipient wetness impregnation method. The n- v hexadecane hydrocracking conditions used were typical of LTFT process (i.e., Temperature = 215 - 310 °C, WHSV = 1 h-1, Pressure = 20 bar, in addition to the H2 /n-C16 ratio of 10). The catalytic activity in all catalyst systems increased with increasing reactor temperature and displayed C4/C12 ratios ≠ 1, evidence of the occurrence of secondary cracking (i.e., a non-ideal hydrocracking behaviour). This was also supported by the shapes of their product distribution profiles, which showed dominant C3 - C7 n-paraffins. Co-feeding H2O with n-C16 into the reactor was found to be detrimental to n-C16 conversion, but promoted the selectivity to iso-paraffins in the product spectrum. Simultaneous introduction of CO and H2O aggravated secondary cracking. Amongst the pristine ZSM-5 zeolite-based catalysts, Pd/P-ZSM-5(77) showed the best catalytic performance. Upon desilication, the performance order changed to favour Pd/D-ZSM-5(50*). For the surfactant-templated supports, Pd/HSZ(N4) showed the most superior hydrocracking performance. Comparison of catalytic activities of the best performing catalyst systems derived from the conventional and surfactant-templated zeolites in the hydrocracking of n-hexadecane, follow the order Pd/D-ZSM-5(50*) > Pd/P-ZSM-5(77) > Pd/HSZ(N4). That is, the pristine and desilicated zeolite-based catalysts performed better than their surfactant-templated zeolite-based counterparts. Therefore, the post-synthesis generation of mesoporosity through desilicating ZSM-5 with a SAR of 50 has proven beneficial for the resulting catalyst system. One of the possible reasons for the relatively inferior hydrocracking performance of the Pd/HSZ(N4) catalyst may be the aluminium-richness of the support (SAR = 40) compared to the conventional ZSM-5-based supports. In summary, catalysts Pd/D-ZSM-5(50*), Pd/P-ZSM-5(77) and Pd/HSZ(N4) are promising for diesel-selective catalysis and need further refinements and exploration.
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Woods, Gary B. "Computer simulation of fluids in zeolites." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237831.

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Seyedeyn-Azad, Fakhry. "Nitrogen monoxide reduction over ZSM-5 zeolite-supported catalysts /." Title page, summary and contents only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phs519.pdf.

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Panpranot, Joongjai. "Hydrothermal aging of zeolite-based catalysts." Morgantown, W. Va. : [West Virginia University Libraries], 1998. http://etd.wvu.edu/templates/showETD.cfm?recnum=274.

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Thesis (M.S.)--West Virginia University, 1998.
Title from document title page. Document formatted into pages; contains xi, 84 p. : ill. Includes abstract. Includes bibliographical references (p. 64-67).
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Folifac, Leo. "Performance of zeolite ZSM-5 synthesised from South African fly ash in the conversion of methanol to hydrocarbons." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2751.

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Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018.
Zeolites have found applications as heterogeneous or solid catalyst in the petrochemical and refining industries. Zeolite ZSM-5 in particular is a highly siliceous solid catalyst with a porous network that consists of medium pore structure (pore openings 5-5.5 A). The solid catalyst (ZSM-5) is well known for its high temperature stability and strong acidity, which makes it an established catalyst used for different petrochemical processes such as Methanol-To-Gasoline (MTG), isomerisation, disproportionation, and cracking. Unlike in the past, the synthesis of zeolite ZSM-5 from other sources that contains silica (Si) and alumina (Al) with the addition of a template (TPBr) as a structure-directing agent is eminent. Its synthesis can be achievable from coal fly ash that is a waste material and a cheap source of Si and Al. Coal fly ash is a waste material that is produced during the combustion of coal to generate electricity. The elemental composition of coal fly ash consists of mostly SiO2 and Al2O3 together with other significant and trace elements. Zeolite ZSM-5 catalyst synthesised from coal fly ash by previous authors required an excessive amount of additional source of silica even though the XRD spectra still show the presence of quartz and mullite phase in the final products. These phases prevented the use of fly ash (solid) as a precursor to synthesise zeolite ZSM-5 products. However, the synthesis of high purity zeolite ZSM-5 products by extracting silica and alumina from South African fly ash and then using it with small amounts of fumed silica was investigated This aim was achieved by fusing fly ash (FA) with sodium hydroxide (NaOH) under hydrothermal condition set at 550 oC for 1 hour 30 minutes. The quartz and mullite phase observed by previous authors was digested by the fusion process. Thereafter, the treatment of fused fly ash filtrate (FFAF) with concentrated H2SO4 (98-99%), precipitated silica and removed Al that therefore increased the Si/Al ratio from 1.97 in fly ash (FA) to 9.5 in the silica extract (named fused fly ash extract). This route was designed to improve the quality of the final products and reduced the amount of fumed silica added to the synthesis mixture prior to hydrothermal synthesis. In this line of investigation, the process of adding fumed silica to the hydrothermal gel was optimised. H-FF1 with a Si/Al ratio of 9.5 was synthesised using the silica extract without the addition of fumed silica. Its XRD, SEM and relative crystallinity results proved that H-FF1 was inactive and hence was not further characterised and utilised in the conversion of methanol to hydrocarbons (MTH). Purer phase zeolite ZSM-5 products (H-FF2 and H-FF3) that were synthesised from silica extract with the addition of small amounts of fumed silica were characterised and successfully used in the methanol to hydrocarbons (MTH) reaction. The synthesised ZSM-5 products had different Si/Al ratio, different morphology, crystal size, BET surface area, and relative crystallinity as well as different trends in the MTH reaction. It was also observed that H-FF2 and H-FF3 (pure phase) solid catalyst deactivated faster than the commercial H-ZSM-5 in the MTH reaction. However, the MTH conversion over H-FF2 competed with that of the commercial H-ZSM-5 within 3 hours of time on stream (TOS) but later deactivated at a faster rate. This was caused by the large crystal size and reduced BET surface area of H-FF2 when compared to the commercial H-ZSM-5. However, H-FF2 performed better than H-FF3 on stream (MTH reaction) due to its smaller crystal size and higher BET. This study has successfully utilised a route that synthesised high purity zeolite ZSM-5 products from the South African fused fly ash extract (FFAE) with the addition of small amounts of fumed silica. The properties of the synthesised zeolite ZSM-5 products (H-FF2 and H-FF3) were similar to that of the commercial H-ZSM-5 as well as active in the MTH reaction. This promoted the utilisation of a waste material (coal fly ash) to synthesise highly siliceous zeolite ZSM-5 products that avoided the presence of mineral phases from fly ash in the final products.
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Axon, Sean Alexander. "MFI-type zeolites synthesized in non-alkaline media." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240100.

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Güneş, Alev Bayraktar Oğuz. "The production of thymoquinone from thymol and carvacrol by using zeolite catalysts/." [s.n.]: [s.l.], 2005. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000391.pdf.

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Books on the topic "Zeolites as catalysts"

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1920-, Degnan Thomas F., and Smith C. Morris, eds. Molecular transport and reaction in zeolites: Design and application of shape selective catalysts. New York, N.Y: VCH, 1994.

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library, Wiley online, ed. Zeolites in industrial separation and catalysis. Weinheim: Wiley-VCH, 2010.

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Scherzer, Julius. Octane-enhancing, zeolitic FCC catalysts: Scientific and technical aspects. New York: M. Dekker, 1990.

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Bachelin, F. Noble metal loaded zeolites as catalysts for alkane hydroconversion. Manchester: UMIST, 1995.

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Naonobu, Katada, Okumura Kazu, and SpringerLink (Online service), eds. Characterization and Design of Zeolite Catalysts: Solid Acidity, Shape Selectivity and Loading Properties. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2010.

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Jan Cornelis van der Waal. Synthesis, characterization and catalytic application of zeolite titanium beta. Delft: Delft Univ. Press, 1998.

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International FEZA Conference (2nd 2002 Taormina, Italy). Impact of zeolites and other porous materials on the new technologies at the beginning of the new millennium: Proceedings of the 2nd International FEZA (Federation of the European Zeolite Associations) Conference, Taormina, Italy, September 1-5, 2002. Amsterdam: Elsevier, 2002.

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Weitkamp, Jens, and Lothar Puppe, eds. Catalysis and Zeolites. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-662-03764-5.

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Cejka, Jirí, Russell E. Morris, and Petr Nachtigall, eds. Zeolites in Catalysis. Cambridge: Royal Society of Chemistry, 2017. http://dx.doi.org/10.1039/9781788010610.

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Chester, Arthur W., and E. G. Derouane. Zeolite characterization and catalysis: A tutorial. Dordrecht: Springer, 2009.

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Book chapters on the topic "Zeolites as catalysts"

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Ogura, Masaru, and Masahiko Matsukata. "Development of Hierarchical Pore Systems for Zeolite Catalysts." In Mesoporous Zeolites, 259–94. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2015. http://dx.doi.org/10.1002/9783527673957.ch8.

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Blauwhoff, P. M. M., J. W. Gosselink, E. P. Kieffer, S. T. Sie, and W. H. J. Stork. "Zeolites as Catalysts in Industrial Processes." In Catalysis and Zeolites, 437–538. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-662-03764-5_7.

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Triantafyllidis, Kostas S., Eleni F. Iliopoulou, Stamatia A. Karakoulia, Christos K. Nitsos, and Angelos A. Lappas. "Mesoporous Zeolite Catalysts for Biomass Conversion to Fuels and Chemicals." In Mesoporous Zeolites, 497–540. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2015. http://dx.doi.org/10.1002/9783527673957.ch15.

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Climent, Maria J., Avelino Corma, and Sara Iborra. "Zeolites as Catalysts for the Synthesis of Fine Chemicals." In Zeolites and Catalysis, 775–826. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527630295.ch25.

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Niwa, Miki, Naonobu Katada, and Kazu Okumura. "Solid Acidity of Zeolites." In Characterization and Design of Zeolite Catalysts, 9–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-12620-8_2.

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Martínez, Agustín, Gonzalo Prieto, Andrés García-Trenco, and Ernest Peris. "Advanced Catalysts Based on Micro- and Mesoporous Molecular Sieves for the Conversion of Natural Gas to Fuels and Chemicals." In Zeolites and Catalysis, 649–85. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527630295.ch21.

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van Bokhoven, Jeroen A., and Carlo Lamberti. "XAS Techniques to Determine Catalytically Active Sites in Zeolites: The Case of Cu-Zeolites." In XAFS Techniques for Catalysts, Nanomaterials, and Surfaces, 299–316. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-43866-5_20.

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Dosa, Melodj, Marco Piumetti, Elahe Davarpanah, Giulia Moncaglieri, Samir Bensaid, and Debora Fino. "Natural Zeolites as Sustainable Materials for Environmental Processes." In Nanostructured Catalysts for Environmental Applications, 367–81. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-58934-9_13.

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Niwa, Miki, Naonobu Katada, and Kazu Okumura. "Catalytic Reaction on the Palladium-Loaded Zeolites." In Characterization and Design of Zeolite Catalysts, 163–79. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-12620-8_9.

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Sauer, J. "Ab Initio Studies on Zeolites and Related Catalysts." In Cluster Models for Surface and Bulk Phenomena, 533–50. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4684-6021-6_42.

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Conference papers on the topic "Zeolites as catalysts"

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Koneti, Siddardha. "Atomically dispersed catalysts on zeolites." In European Microscopy Congress 2020. Royal Microscopical Society, 2021. http://dx.doi.org/10.22443/rms.emc2020.1049.

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Bond, Gary, A. Halman, H. Eccles, R. Mao, S. Pollington, P. Hinde, V. Demidyuk, and A. Gkelios. "A COMPARATIVE STUDY OF MICROWAVE AND BARRIER DISCHARGE PLASMA FOR THE REGENERATION OF SPENT ZEOLITE CATALYSTS." In Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9936.

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Due to their acid characteristics and pore structure, which can induce high product selectivity; zeolite catalysts are used extensively in industry to catalyse reactions involving hydrocarbons. However, these catalysts can suffer from deactivation due to cracking reactions that result in the deposition of carbon leading to poisoning of the acid sites and blocking of the pores [1]. Depending upon the reaction and the particular catalyst involved this deactivation may take place over several months or even years but in some cases occurs in minutes. Therefore, zeolite catalysts are frequently reactivated / regenerated. This generally involves a thermal treatment involving air which results in oxidation of the carbon [2]. However, the oxidation of carbon is highly exothermic, and if not carefully controlled, results in the generation of exceedingly high localized temperatures which can destroy the zeolite structure and result in subsequent loss of catalyst activity. More conservative thermal treatments can result in incomplete regeneration and again a catalyst displaying inferior activity. This paper explores the use of non-thermal plasma which had been either generated using microwaves or via a barrier discharge to regenerate spent zeolite catalysts. The catalyst, H-mordenite, was tested for the disproportionation of toluene (Figure 1) using conventional heating. The spent catalyst was then regenerated using a plasma or conventional thermal treatment before having its activity re-evaluated for the toluene disproportionation reaction as previous. Fig. 1. Reaction Scheme for Toluene Disproportionation. Interestingly, not only is plasma regeneration highly effective but also catalysts can be regenerated in greatly reduced times. There is an additional advantage in that plasma regeneration can impart physical properties that result in a zeolite that is resistant to further deactivation. However, the results are highly dependent upon the experimental conditions involved for plasma regeneration. References Wu J, Leu L., Appl. Catal., 1983; 7:283-294. M. Guisnet and P. Magnoux, Deactivation of Zeolites by Coking. Prevention of Deactivation and Regeneration. In: Zeolite Microporous Solids: Synthesis, Structure, and Reactivity. E.G. Derouane, F Lemos, C. Naccache, F. Ramôa Ribeiro, Eds. Pages 437-456. Springer 1992.
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Das, Randip K., B. B. Ghosh, Souvik Bhattacharyya, and Maya DuttaGupta. "Catalytic Control of SI Engine Emissions Over Ion-Exchanged X-Zeolites." In ASME 1997 Turbo Asia Conference. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-aa-077.

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Three catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper, Iron and Nickel metal ions and tested in a SI engine exhaust for a wide range of exhaust and operating conditions. Of the three catalysts, the Cu-X catalyst exhibits the best NOx and CO conversion performance while Ni-X shows slightly better performance compared to the Fe-X catalyst at any catalyst temperature. Unlike noble metals, the doped X-zeolite catalysts, studied here, exhibit significant NOx reduction for a wide λ range and exhibit a slow rate of decrease with increase in λ ratio. Back pressure developed across the catalyst bed is found to be well-afford able and power loss due to back pressure is only 0.216% at space velocity of 52500 /h. During 30 hours of testing of each catalyst, no significant deactivation of any catalyst is observed.
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Dzinun, Hazlini, and Mohd Hafiz Dzarfan Othman. "A Review on Modification of Zeolite for Photocatalytic Applications." In Conference on Center of Diploma Studies (CeDS) 2020/1. Penerbit UTHM, 2020. http://dx.doi.org/10.30880/mari.2020.01.01.002.

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Zeolites are microporous crystalline alumina-silicate materials, widely used as catalysts, ion exchangers and adsorbents due to their chemical structure and surface properties. The unique properties of zeolite such as high adsorption capacity and cation exchange make it interesting to be used as a support material. This review article presents the details of various researches of zeolite used as photocatalyst in photocatalytic application. The modifications of zeolite using several methods are described in details for photocatalytic enhancement. The effect of zeolite nanoparticles in membrane fabrication also provided in this article. Furthermore, the efficiency of zeolite used as adsorbents and photocatalyst in the photocatalytic application also presented.
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Simakov, A., N. Bogdanchikova, I. Tuzovskaya, E. Smoletseva, A. Pestryakov, M. Farias, and M. Avalos. "Catalysts based on gold nanosized species incorporated into zeolites." In Optics & Photonics 2005, edited by Martin W. McCall, Graeme Dewar, and Mikhail A. Noginov. SPIE, 2005. http://dx.doi.org/10.1117/12.616102.

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Sugiarti, S., D. D. Septian, H. Maigita, N. A. Khoerunnisa, S. Hasanah, T. Wukirsari, N. Hanif, and Y. B. Apriliyanto. "Investigation of H-zeolite and metal-impregnated zeolites as transformation catalysts of glucose to hydroxymethylfurfural." In THE 8TH INTERNATIONAL CONFERENCE OF THE INDONESIAN CHEMICAL SOCIETY (ICICS) 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0001789.

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Wang, Tianyou, Shuliang Liu, Hongjun Xu, Xing Li, Maolin Fu, Landong Li, and Naijia Guan. "Evaluation of In-Situ Synthesized Monolithic Metal-MFI/Cordierite Catalysts to Remove NOx From Lean Exhaust." In ASME 2005 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/icef2005-1253.

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In this study, ZSM-5 zeolites were successfully in situ synthesized on the surface of honeycomb cordierite substrate and certified by XRD and SEM techniques. Strong interaction between zeolite and substrate has been found during in-situ synthesis, and hydrothermal stabilities of the zeolites was improved by entailing. The in-situ synthesized monolithic ZSM-5/cordierite showed superior thermal and hydrothermal stabilities. Cu-ZSM-5/cordierite was prepared by ion-exchange and impregnation methods were studied as catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NOx) in a lean-burn gasoline engine. Engine test results show that NOx emission was decreased by reductants of HC and CO in the exhaust gas without any other extra reducing agents. It also exhibited high activities. Using Cu-ZSM-5/cordierite, the maximum NOx conversion efficiency to N2 reached to 64% at the exhaust temperature of 400 °C and the gas hourly space velocity (GHTV) of 25 000/h. Meanwhile, the HC conversion efficiency was about 60%, while CO was little converted. Cu-ZSM-5/cordierite also showed good duration and anti-poison properties. Furthermore, the activated temperature of the Cu-ZSM-5/cordierite was decreased and the NOx conversion was increased via addition of iridium as a modifier.
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Endo, Yoshinori, Joe Nishikawa, Hironori Iwakura, Masaaki Inamura, Takashi Wakabayashi, Yuunosuke Nakahara, Masataka Ogasawara, and Sumio Kato. "Development of Highly Durable Zeolites as Hydrocarbon Trap Materials for Automotive Catalysts." In WCX World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2018. http://dx.doi.org/10.4271/2018-01-0947.

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DE TARSO FIGUEIREDO GRECCO, SAULO, PAULO SÉRGIO SANTANA NOBRE, ERNESTO ANTÔNIO URQUIETA-GONZÁLEZ, and MARIA DO CARMO RANGEL. "TWO-STEP SYNTHESIS PROCEDURE OF BETA ZEOLITES: MESOPOROSITY AND PERFORMANCE AS ACID CATALYSTS." In Proceedings of the 5th International Symposium. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812779168_0061.

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Fedorova, E. D., L. A. Buluchevskaya, E. A. Buluchevskiy, A. V. Lavrenov, and E. R. Saybulina. "Isodewaxing of hydrocarbon biodiesel using catalysts based on zeolites and anion-modified metal oxides." In 21ST CENTURY: CHEMISTRY TO LIFE. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5122929.

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Reports on the topic "Zeolites as catalysts"

1

Monnier, J. Hydrotreatment of coal-derived middle distillates with catalysts supported on zeolites or titania. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1986. http://dx.doi.org/10.4095/302675.

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Sachtler, Wolfgang M. H. Chemical Interactions in Multimetal/Zeolite Catalysts. Office of Scientific and Technical Information (OSTI), April 2004. http://dx.doi.org/10.2172/899300.

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Sachtler, W. M. H. Chemical interactions in multimetal/zeolite catalysts. Office of Scientific and Technical Information (OSTI), December 1992. http://dx.doi.org/10.2172/6905684.

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Sachtler, W. M. H. Chemical interactions in multimetal/zeolite catalysts. Office of Scientific and Technical Information (OSTI), November 1991. http://dx.doi.org/10.2172/5977368.

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Sachtler, W. M. H. Chemical interactions in multimetal/zeolite catalysts. Office of Scientific and Technical Information (OSTI), February 1992. http://dx.doi.org/10.2172/5837744.

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Sachtler, W. M. H. Chemical interactions in multimetal/zeolite catalysts. Office of Scientific and Technical Information (OSTI), February 1992. http://dx.doi.org/10.2172/5837780.

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Sachtler, W. M. H. Chemical interactions in multimetal/zeolite catalysts. Office of Scientific and Technical Information (OSTI), February 1992. http://dx.doi.org/10.2172/5830229.

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Eckert, J., A. Bug, and J. M. Nicol. Characterization of active sites in zeolite catalysts. Office of Scientific and Technical Information (OSTI), November 1997. http://dx.doi.org/10.2172/548615.

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Tsao, G. T. [Zeolite catalysis in conversion of cellulosics]. Office of Scientific and Technical Information (OSTI), January 1992. http://dx.doi.org/10.2172/6849507.

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Tsao, G. T. [Zeolite catalysis in conversion of cellulosics]. Office of Scientific and Technical Information (OSTI), December 1992. http://dx.doi.org/10.2172/10122903.

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