Search for: catalyst
Total 714 records
Article International Journal of Modern Physics B ; Volume 22, Issue 18-19 , 2008 , Pages 3278-3288 ; 02179792 (ISSN) ; Kazemeini, M ; Kazemian, H ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd 2008
Calcined Na-ZSM-5 zeolite was directly reacted with the chloroauric acid solution in different concentrations and pH for gold loading process. The synthesized Au/ZSM-5 catalyst was then characterized using XRD, BET, SEM, TEM and EDS techniques. In order to evaluate its catalytic activity, effect of temperature on CO conversion was investigated. © 2008 World Scientific Publishing Company
Article Monatshefte fur Chemie ; Volume 138, Issue 4 , 2007 , Pages 363-379 ; 00269247 (ISSN) ; Rahimi, A ; Pourjavadi, A ; Sharif University of Technology
Polymer supported reagents have found many applications in recent years. Scientists in research laboratories of agrochemical and pharmaceutical industries now routinely utilize these compounds to prepare ensembles of small organic molecules for screening. This review is aimed to highlight some of the most important applications of these promising materials in organic synthesis. Furthermore, an extensive listing of polymeric reagents that were recently used in organic synthesis is included. © Springer-Verlag 2007
Rapid and selective acetalization of aldehydes using anhydrous copper sulfate supported on silica gel (CuSO4/SiO2) under microwave irradiation in solvent-free conditions, Article Letters in Organic Chemistry ; Volume 2, Issue 2 , 2005 , Pages 151-155 ; 15701786 (ISSN) ; Oskoui, A. A ; Boinee, H. Z ; Sharif University of Technology
CuSO4/SiO2 is found to be an efficient and selective medium for the acetalization of aldehydes in the presence of ketones in solvent-free conditions under microwave irradiation. © 2005 Bentham Science Publishers Ltd
Study of Deactivation of Carbon Nanotubes Supported on Cobalt Catalysts in Fischer-Tropsch Synthesis, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad ; Rohani, Ali Asghar
Purified RIPI–CNT was used as support material for the preparation of cobalt FTS catalysts. Carbon nanotubes supported catalysts (S1–S4) were prepared with loadings of 15, 20, 30 and 40 wt.%. The FT synthesis was carried out in a fixed-bed micro reactor. Deactivation factors of cobalt catalysts supported on carbon nanotubes in FT synthesis is investigated. Using carbon nanotubes as cobalt catalyst support was found to cause the reduction temperature of cobalt oxide species to shift to lower temperatures. The strong metal-support interactions are reduced to a large extent and the reducibility of the catalysts improved significantly. Then, the main reason for the catalyst deactivation will be...
Modified Catalyst Based on Zeolite: Preparation, Characterization and Application as Catalysts for the Isomerization of C8 Aromatics, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza ; Salari, Hadi
In this project Mordinate and Eu-1 zeolite were synthesized by hydrothermal method and then bifunctional catalysts including acid-base zeolite and Pt-Al2O3 metal base were mixed and made using a planetary mill. The modified catalysts were detected by various methods such as XRD, SEM, FTIR. The aim of this project is to synthesize and characterize the modified catalysts and to escalate their catalytic properties. Our focus is primarily on the synthesis of zeolite-based catalysts modified with unique features such as having active acid sites, high thermal stability and appropriate selectivity for the purpose of investigating the mechanism and kinetics of the C8 aromatic Compounds...
Zinc oxide as a useful and recyclable catalyst for the one-pot synthesis of 2,4,6-trisubstituted-1,3,5-trioxanes under solvent-free conditions, Article Industrial and Engineering Chemistry Research ; Volume 52, Issue 28 , 2013 , Pages 9538-9543 ; 08885885 (ISSN) ; Nasr, A. H ; Rabiee, S ; Adibi, E ; Sharif University of Technology
Different aliphatic and aromatic aldehydes such as isobutyraldehyde, ethanal, n-propanal, n-butanal, n-hexanal, n-octanal, and substituted benzaldehydes were cyclotrimerized into their corresponding 2,4,6-trialkyl-1,3, 5-trioxanes in the presence of commercial bulk zinc oxide at room temperature under neat conditions within a short span of time with high yield and excellent selectivity. Liquid products were formed as a separate phase and were decanted easily, whereas solid products were isolated by simple extraction. Effect of different additives, mol % of catalyst, kind of substrate, and reaction temperature were examined on the progress of cyclotrimerization reaction
Supported cobalt oxide nanoparticles as efficient catalyst in esterification and amidation reactions, Article Catalysis Communications ; Volume 59 , January , 2014 , Pages 122-126 ; 15667367 (ISSN) ; Raessi, M ; Arancon, R. A. D ; Saidi, M. R ; Luque, R ; Sharif University of Technology
Co/SBA-15 nanoparticle catalysts (CoNP) were prepared using a commonly adapted synthetic route and then utilised for esterification and amidation reactions using aromatic and linear chain compounds for the production of long chain esters and amides. The study shows that the use of CoNP catalysts favours the use of aromatic reactants with electron donating substituents specifically in the para position. For the amidation reaction, good to excellent yields were obtained demonstrating tolerance towards differently substituted aromatic compounds. Overall, the synthesized catalysts proved to be efficient and highly versatile, and recyclable under the investigated conditions
Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) ; Soltanieh, M ; Rashidzadeh, M ; Sharif University of Technology
This article presents the research results on production and performance of palladium-only catalytic converters. Monolith is used as catalyst carrier and gamma alumina as substrate. Dipping method is used for monolith washcoating. Palladium as the active metal is impregnated on gamma alumina using wet impregnation to produce catalyst samples. The effects of factors such as percent solid in slurry, milling time, calcination time and temperature, pH and existence of Al(NO3)3 on wash-coat characteristics were studied experimentally. SEM, XRD, and BET tests were carried out on the samples. Catalyst performance was tested in an experimental reactor that was designed for this research. The results...
Cobalt supported on CNTs-covered γ- and nano-structured alumina catalysts utilized for wax selective Fischer-Tropsch synthesis, Article Journal of Natural Gas Chemistry ; Volume 21, Issue 6 , 2012 , Pages 713-721 ; 10039953 (ISSN) ; Kazemeini, M ; Khorasheh, F ; Zarkesh, J ; Rashidi, A ; Sharif University of Technology
Cobalt supported on carbon nanotubes (CNTs)-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis (FTS). Problems associated with shaping of Co/CNTs into extrudates or pellets as well as catalyst attrition rendered these materials unfavorable for industrial applications. In this investigation regular γ- and nano-structured (N-S) alumina as well as CNTs-covered regular γ- and N-S-alumina supports were impregnated by cobalt nitrate solution to make new cobalt-based catalysts which were also promoted by Ru. The catalysts were characterized and tested in a micro reactor to evaluate their applicability in FTS. γ-Al2O3 was prepared by...
Effects of nano graphene oxide as support on the product properties and performance of Ziegler-Natta catalyst in production of UHMWPE, Article Polymers for Advanced Technologies ; Volume 26, Issue 4 , 2015 , Pages 315-321 ; 10427147 (ISSN) ; Ramazani, S. A ; Khorasheh, F ; Baghalha, M ; Bahrami, H ; Sharif University of Technology
John Wiley and Sons Ltd 2015
The synthesis of mono- and bi-supported Ziegler-Natta catalysts using magnesium etoxide Mg(OEt)2 and graphene oxide (GO) as catalyst support for production of Ultra High Molecular Weight Polyethylene (UHMWPE) is reported in this investigation. Nano-graphene oxide was prepared by the modified Hummer's method and its structure was analyzed by XRD and FTIR indicating the presence of hydroxyl groups on graphene oxide and the formation of an exfoliated structure. The activity of TiCl4/Mg(OEt)2, TiCl4/Mg(OEt)2-GO, and TiCl4/GO catalysts in terms of grams of PE produced per mmol of Ti per hour was experimentally obtained for catalysts with different ratios of co-catalyst (triisobutylaluminium) to...
Article Journal of Molecular Catalysis A: Chemical ; Volume 365 , 2012 , Pages 55-59 ; 13811169 (ISSN) ; Hosseini, S. H ; Soleyman, R ; Sharif University of Technology
A dual acidic heterogeneous organocatalyst was synthesized by copolymerization of acidic ionic liquid monomer (vinyl-3-(3-sulfopropyl) imidazolium hydrogen sulfate [VSim][HSO 4]) and ionic liquid crosslinker (1,4-butanediyl-3,3′-bis-l-vinyl imidazolium dihydrogen sulfate). The resulting ionic heterogeneous catalyst is shown to be an efficient dual acidic organocatalyst for synthesis of dihydropyrimidines using the Biginelli synthetic route under mild reaction conditions in high yields. Since monomers make the catalyst bed, crosslinked poly(ionic liquid) will have high loading level of acidic groups comparing to other heterogeneous acid catalysts. Despite of conventional heterogeneous ionic...
Modeling and sensitivity analysis of styrene monomer production process and investigation of catalyst behavior, Article Computers and Chemical Engineering ; Volume 40 , 2012 , Pages 1-11 ; 00981354 (ISSN) ; Ebrahimi, A. N ; Ramazani S.A., A ; Abdollahzadeh, H ; Sharif University of Technology
In this work, a fundamental kinetic model based upon the Hougen-Watson non-porosity formalism was derived and used to simulate dehydrogenation and oxidation axial flow reactors. In addition, partial pressure profiles of components during styrene production process inside porous catalyst were obtained using Dusty-Gas model. The preservation equations are adopted to calculate temperature and flow profiles in the reactors filled with iron-potassium promoted catalyst pellets. The presented mathematical model for ethylbenzene dehydrogenation consists of nonlinear simultaneous differential equations with multiple dependent variables. Simulation results such as selectivity and operating temperature...
Bacterial leaching of a spent Mo-Co-Ni refinery catalyst using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, Article Hydrometallurgy ; Volume 106, Issue 1-2 , February , 2011 , Pages 26-31 ; 0304386X (ISSN) ; Borghei, S. M ; Mousavi, S. M ; Sharif University of Technology
A spent processing catalyst from an Iranian oil refinery was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize Al, Co, Mo and Ni from the spent catalysts under optimized conditions in batch cultures. The characteristics of the bioleach solution (pH, Eh, cell concentration and Fe(II)/Fe(III) concentration) were determined along with the concentration of metal values extracted from the catalyst. The results showed that after bioleaching using A. ferrooxidans in the presence of ferrous sulfate, maximum extractions of 63% Al, 96% Co, 84% Mo and 99% Ni were achieved after 30 days at pH 1.8-2.0. However, the...
Magnetic GO-PANI decorated with Au NPs: a highly efficient and reusable catalyst for reduction of dyes and nitro aromatic compounds, Article Applied Organometallic Chemistry ; Volume 31, Issue 12 , 2017 ; 02682605 (ISSN) ; Doroudian, M ; Abedin Moghanaki, A ; Bennett, C ; Sharif University of Technology
Due to the high activity of Au nanoparticles (NPs) for various reactions, many researchers have tried to develop heterogeneous catalysts in order to prevent irreversible agglomeration of Au NPs. Herein, magnetic graphene oxide modified with polyaniline (PANI) was used as a support for Au NPs that brings together advantages including: uniform dispersal of the catalyst in water,alarge surface area related to the graphene oxide; easy electron transfer in chemical reactions and good attachment of Au NPs to the support associated with PANI; and finally facile recovery in the presence of a magnetic field. Catalytic reduction of different analytes (Congo red, methylene blue, rhodamine B and 4-nitro...
Production of renewable hydrogen through aqueous-phase reforming of glycerol over Ni/Al2O3–MgO nano-catalyst, Article International Journal of Hydrogen Energy ; Volume 43, Issue 2 , 2018 , Pages 614-621 ; 03603199 (ISSN) ; Kazemeini, M ; Larimi, A ; Maleki, H ; Sharif University of Technology
Elsevier Ltd 2018
In this study, a series of Ni nano-catalysts supported on Al2O3 and MgO were prepared through the co-precipitation technique. Effects of the Al/Mg ratio on physicochemical characteristics of Ni/Al2O3–MgO catalysts were examined. Moreover, catalytic performance was investigated in order to determine the optimum catalyst for H2 production in aqueous phase reforming (APR) of glycerol. It was revealed that, the APR activity of synthesized catalysts strongly depended on the aforementioned ratio. In addition, it was observed that, the catalytic activity of Ni/MgO and Ni/Al2O3 samples were both lower than that of the corresponding mixed oxide supports. Furthermore, it was shown that, amongst the...
Kinetic and morphological study of a magnesium ethoxide-based Ziegler-Natta catalyst for propylene polymerization, Article Polymer International ; Volume 58, Issue 1 , 2009 , Pages 40-45 ; 09598103 (ISSN) ; Ramazani Saadatabadi, A ; Hiraoka, Y ; Kim, S. Y ; Taniike, T ; Terano, M ; Sharif University of Technology
Background: Kinetic andmorphological aspects of slurry propylene polymerization using a MgCl2-supported Ziegler-Natta catalyst synthesized from a Mg(OEt)2 precursor are investigated in comparison with a ball-milled Ziegler-Natta catalyst. Results: The two types of catalyst show completely different polymerization profiles: mild activation and long-standing activity with good replication of the catalyst particles for the Mg(OEt)2-based catalyst, and rapid activation and deactivation with severe fragmentation of the catalyst particles for the ball-milled catalyst. The observed differences are discussed in relation to spatial distribution of TiCl4 on the outermost part and inside of the...
Article Scientia Iranica ; Volume 16, Issue 2 C , 2009 , Pages 94-98 ; 10263098 (ISSN) ; Ebrahimi, F ; Saidi, M. R ; Sharif University of Technology
A mild and practically-convenient one-pot procedure for the direct Mannich reaction has been developed using a condensation of amines, aldehydes and unmodified ketones under solvent free conditions in the presence of Znl 2 with good to excellent yields. The present methodology offers several advantages, such as excellent yields, simple procedures, short reaction times and milder conditions with very small amounts of catalyst. Furthermore, it is the first time that the catalytic activity of several catalysts under solvent free conditions has been studied. It was found that both the diastereoselectivity and the rate of reaction were improved with various Lewis acids and metal oxides. However,...
Optimizing Structure of Catalysts and Development of Kinetic Parameters for Synthesis Gas to Olefin Reaction, Ph.D. Dissertation Sharif University of Technology ; Ghotbi, Siroos ; Bozorg Mehri, Ramin ; Zarrinpashne, Saeid
Synthesis gas to light olefin reactions especially propylene production is one of the important path for clean fuel production in gas conversion processes. The object of this study is to define true kinetic model of process first step (e.g. Synthesis gas to light Olefins). For that, kinetic model for Co/Mn/TiO2 catalyst, which has the best conversion and selectivity for propylene, has been developed. Kinetic reaction parameters were measured by kinetic modeling in (220-300)0C temperature , (1-5)bar pressure , H2/CO=(1:3) and (450-600)hr-1 space velocity .After studying with significant models ,the best fitting can obtained with "KPCO P 1/2H2/(1+aPco+bPH2 1/2)2"equation. Later to...
Transesterification of waste cooking oil to biodiesel using KOH/γ-Al2O3 catalyst in a new two-impinging-jets reactor, Article Industrial and Engineering Chemistry Research ; Vol. 53, Issue. 31 , 2014 , Pages 12238-12248 ; ISSN: 08885885 ; Molaei Dehkordi, A ; Sharif University of Technology
In this article, the transesterification of waste cooking oil (WCO) to biodiesel fuel (BDF) has been studied using KOH loaded on millimetric γ-Al2O3 particles in a novel type of two-impinging-jets reactor (TIJR). The effects of various parameters such as KOH loading (wt %), catalyst loading, and methanol-to-oil molar ratio on the BDF yield were studied. The catalyst particles with a KOH loading of 25 wt % at appropriate reaction conditions (i.e., catalyst loading = 4 wt % and methanol-to-oil molar ratio = 15:1) and at 65 °C were used in the TIJR. The influences of various operating and design parameters such as jet Reynolds number value, feed flow rate, jet diameter, and the internozzle...
Selective oxidation of sulfides to sulfoxides by a molybdate-based catalyst using 30% hydrogen peroxide, Article Catalysis Communications ; Vol. 52, issue , July , 2014 , pp. 16-21 ; ISSN: 15667367 ; Shakourian-Fard, M ; Hashemi, M. M ; Sharif University of Technology
An efficient method is reported for selective oxidation of various types of sulfides to sulfoxides and sulfones in good to high yields using 30% H 2O2 in the presence of catalytic amounts of molybdate-based catalyst in acetonitrile as solvent at room temperature. The catalyst can be easily recovered and reused for seven reaction cycles without considerable loss of activity