Search for: catalysts
Total 722 records
Synthesis of α-aminophosphonates in the presence of a magnetic recyclable Fe3O4@SiO2-2mimSO3H nanocatalyst, Article Bulletin of the Chemical Society of Japan ; Vol. 87, issue. 9 , 2014 , pp. 982-987 ; ISSN: 00092673 ; Rezayan, A. H ; Kheirjou, S ; Bayat, A ; Hashemi, M. M ; Sharif University of Technology
A highly efficient magnetic Brønsted acid catalyst was synthesized based on immobilization of 2-methylimidazole functionalized by chlorosulfonic acid on the surface of silica-coated magnetic nanoparticles (Fe3O4@SiO2-2mimSO3H). The catalyst has an excellent activity and recyclable for at least 6 reaction runs and is proven to be highly effective in the synthes is of α-aminophosphonate compounds in a green way. The facile recovery of the catalyst is carried out by applying an external magnet device. It is both "green" and efficient. The catalyst was fully characterized by techniques of TEM, SEM, FT-IR, TGA, and elemental analysis (CHNS)
Development of an empirical model for catalyst lifetime in isobutane/ butene alkylation, Article Industrial and Engineering Chemistry Research ; Volume 42, Issue 17 , 2003 , Pages 3886-3892 ; 08885885 (ISSN) ; Sahebdelfar, S ; Khorasheh, F ; Badakhshan, A ; Sharif University of Technology
American Chemical Society 2003
Dimensional analysis of the governing equations in liquid-phase, solid-acid-catalyzed alkylation was used to develop an empirical model for the catalyst lifetime in terms of important operating variables. It was found that the dimensionless catalyst lifetime in a continuous stirred tank reactor was a function of four dimensionless groups, incorporating all important kinetic and operating variables. A power-law correlation was found to be adequate in representing the available experimental data. Because the alkylation reactions are highly diffusion-limited, it was shown that only three of the four exponents in the power-law correlation were independent. As such, the fourth exponent was...
Treatment of diatomaceous earth to obtain its catalyst support, Article Scientia Iranica ; Volume 10, Issue 3 , 2003 , Pages 350-356 ; 10263098 (ISSN) ; Kazemeini, M ; Sharif University of Technology
Sharif University of Technology 2003
Treatment of diatomaceous earth with sulfuric acid reduces mineral and organic impurities, such as Fe2O3, Al2O3 and alkali metal oxides (CaO, MgO and Na2O). In addition, wettability and porosity of the acid-treated diatomite are greatly enhanced. Acid-treated diatomite is suitable to be used as a siliceous support for catalysts, due to high silica content (> 90%), amorphous structure with low cristobalite and quartz phases, appropriate Brunauer-Emmett-Teller surface area, high absorptive capacity, good mechanical strength after calcinations and low cost of production. In the first part of this study, the influence of temperature, sulfuric acid concentration, acid-diatomite mass ratio and...
CoSALEN as a new catalyst for oxidation of fullerene C60, Article Journal of Coordination Chemistry ; Volume 62, Issue 20 , 2009 , Pages 3384-3390 ; 00958972 (ISSN) ; Tangeysh, B ; Sharif University of Technology
The effect of CoSALEN on anti-oxidative properties of fullerene C60 in the presence of O2 in cumene was investigated. A comparison was made between the role of the CoSALEN as a catalyst in the C60 oxidation and oxidation in the presence of an initiator, i.e., AIBN. A mechanism is proposed for the catalytic role of CoSALEN in oxidation of C60. Oxidation of octadecylaminofullerene C60 at the same conditions reveals that oxidation could be a result of hydroperoxidation of the unreacted sites of C60. We conclude that C60 as well as its aminoderivatives enhance the efficiency of CoSALEN in the oxidation of cumene due to their radical scavenging property of their unreacted double-bond sites. ©...
Ultra-small and highly dispersive iron oxide hydroxide as an efficient catalyst for oxidation reactions: a swiss-army-knife catalyst, Article Scientific Reports ; Volume 11, Issue 1 , 2021 ; 20452322 (ISSN) ; Mousazade, Y ; Zand, Z ; Bagherzadeh, M ; Najafpour, M. M ; Sharif University of Technology
Nature Research 2021
Ultra-small and highly dispersive (< 10 nm) iron oxide hydroxide is characterized by some methods. The compound is an efficient and stable catalyst for alcohol oxidation, organic sulfide oxidation, and epoxidation of alkenes in the presence of H2O2. The electrochemical oxygen-evolution reaction of the iron oxide hydroxide is also tested under acidic, neutral, and alkaline conditions. In the presence of the iron oxide hydroxide, excellent conversions (75–100%) and selectivities of substrates (92–97%), depending on the nature of the sulfide, were obtained. Benzylalcohols having electron-donating and-withdrawing substituents in the aromatic ring were oxidized to produce the corresponding...
Manganese and cobalt-terephthalate metal-organic frameworks as a precursor for synthesis of Mn
Inorganic Chemistry Communications
; Zare, M
; Bagherzade, M
Sharif University of Technology
2O 3, Mn 3O 4 and Co 3O 4 nanoparticles: Active catalysts for olefin heterogeneous oxidation
The thermal decomposition of manganese and cobalt-terephthalate Metal-Organic Framework precursors was utilized as a synthetic route for fabrication of Co
3O 4, Mn 3O 4 and Mn 2O 3 nanoparticles. The prepared metal oxide nanoparticles of Co 3O 4, Mn 3O 4 and Mn 2O 3 possess average size diameter of 40, 60 and 80 nm respectively. The findings demonstrate that spinel structure nanoparticles of Co 3O 4 and Mn 3O 4 exhibit efficient catalytic activity toward heterogeneous olefin epoxidation in the presence of tert-butyl hydroperoxide. In...
Magnetic nanoparticles entrapped in the cross-linked poly(imidazole/imidazolium) immobilized Cu(ii): An effective heterogeneous copper catalyst, Article RSC Advances ; Volume 4, Issue 87 , 2014 , Pages 46418-46426 ; ISSN: 20462069 ; Hosseini, S. H ; Zohreh, N ; Bennett, C ; Sharif University of Technology
Anchoring of copper sulfate in layered poly(imidazole-imidazolium) coated magnetic nanoparticles provided a highly stable, active, reusable, high loading, and green catalyst for the click synthesis of 1,2,3-triazoles via a one-pot cycloaddition of alkyl halide, azide, and alkyne (Cu-A3C). The catalyst was characterized by FTIR, TGA, TEM, SEM, XRD, EDAX, VSM and AAS. High selectivity, broad diversity of alkyl/benzyl bromide/chloride and alkyl/aryl terminal alkynes, and good to excellent yields of products were obtained using 0.7 mol% catalyst. The catalyst was readily recovered and reused up to 6 times without significant loss of activity
Synthesis of quinazolin-4(3H)-one derivatives using heteropolyacids as heterogeneous and recyclable catalysts, Article Asian Journal of Chemistry ; Volume 23, Issue 4 , 2011 , Pages 1588-1590 ; 09707077 (ISSN) ; Hashemi, M. M ; Heravi, M. M ; Bamoharram, F. F ; Sharif University of Technology
A highly efficient and simple procedure for the synthesis of quinazolin-4(3H)-ones from the condensation of 2-aminobenzamide with triethylorthoesters in presence of a catalytic amounts of heteropolyacids in various solvents is reported
Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes, Article Journal of Industrial and Engineering Chemistry ; 2015 ; ISSN: 1226086X ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.% of palladium on activated carbon)...
Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes, Article Journal of Industrial and Engineering Chemistry ; Volume 28 , August , 2015 , Pages 202-210 ; 1226086X (ISSN) ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
Korean Society of Industrial Engineering Chemistry 2015
Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl
2 and Pd(OAc) 2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl 2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.%...
Immobilized tungstate on magnetic poly(2-ammonium ethyl acrylamide): A high loaded heterogeneous catalyst for selective oxidation of sulfides using H2O2, Article Journal of Industrial and Engineering Chemistry ; Volume 44 , 2016 , Pages 73-81 ; 1226086X (ISSN) ; Hosseini, S. H ; Pourjavadi, A ; Soleyman, R ; Bennett, C ; Sharif University of Technology
Korean Society of Industrial Engineering Chemistry 2016
A heterogeneous tungstate-based catalyst has been prepared for selective oxidation of sulfides to sulfoxides in the presence of 30% H2O2. The catalyst was prepared via immobilization of high amounts of WO4 2− onto the cross-linked poly(ammonium ethyl acrylamide) coated magnetic nanoparticles (MNP). FT-IR, TEM, TGA, VSM, XRD, EDX, and CHN analysis were used for characterization of catalyst. Variety of sulfides successfully converted to the related sulfoxides using 1 mol% of catalyst at room temperature in high yields. The catalyst was easily recovered and reused up to 6 times without loss of activity
Application of Magnetic Bi-and Trimetallic Nanocatalysts Based on Fe in the Synthesis of Polycyclic Heterocycles, M.Sc. Thesis Sharif University of Technology ; Matloubi Moghaddam, Firooz ; Sajjadi, Ali Akbar
Nowadays, two metallic catalyst are used in many organic reaction; so,different types of these catalytic systems have been synthesized up to now and been employed. One of these systems that recently has attracted many attention is magnetic two metallic nanocatalyst, that showing very good activity due to the synergistic effect between the two metal and fine particle size.On the other hand, poly cyclic heterocyclic compounds are one the main families of organic compounds having many application in biochemicals and pharmaceuticals. The main purpose of this project is to introduce a new method for the synthesize of these compounds such as tetrazoles and 1,4-dihydropyridines, using two- and...
Thermokinetic study of Fischer-Tropsch synthesis on Fe2Cu 1 and FeCu surfaces with comparison to Fe(110) and Cu(111) catalysts by the UBI-QEP method, Article Journal of the Iranian Chemical Society ; Vol. 11, issue. 5 , 2014 , pp. 1305-1310 ; SSN: 1735-207X ; Sajjadifar, S ; Sharif University of Technology
The purpose of this study is to predict the activation barriers and enthalpy for elementary steps in the process of Fischer-Tropsch (F-T) on the surfaces of Fe(110), Cu(111) and Fe/Cu alloys catalyst using "Unity Bond Index-Quadratic Exponential Potential" method aimed at predicting the activity and selectivity on the basis of energy criteria. The elementary steps, such as dissociation of CO, hydrogenation of carbidic carbon, C-C chain growth by insertion of CH2 versus CO into the metal-alkyl bonds, and chain termination, which lead to hydrocarbons (alkanes versus α-olefins) or oxygenates are discussed in detail. The results show that metallic Fe(110) is necessary to produce the carbidic...
Cross-linked poly (dimethylaminoethyl acrylamide) coated magnetic nanoparticles: a high loaded, retrievable, and stable basic catalyst for the synthesis of benzopyranes in water, Article RSC Advances ; Vol. 4, issue. 91 , 2014 , p. 50047-50055 ; Hosseini, S. H ; Pourjavadi, A ; Bennett, C ; Sharif University of Technology
A novel heterogeneous catalyst has been synthesized based on the distillation-precipitation-polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups using N,N-dimethylethylenediamine. The resulting poly(dimethylaminoethyl acrylamide) coated magnetic nanoparticles (MNP@PDMA) catalyst was characterized using an array of sophisticated analytical techniques, including FT-IR, TGA, SEM, TEM, CHN, vibrating sample magnetometer (VSM), and XRD analysis. The resulting heterogeneous base catalyst allowed the performance of a domino Knoevenagel condensation/Michael addition/cycloaddition reaction toward the synthesis of...
Simple methodology for the aerobic N-methylation of substituted anilines catalyzed by zirconium oxychloride octahydrate, ZrOCl2·8H 2O, Article Industrial and Engineering Chemistry Research ; Volume 52, Issue 32 , 2013 , Pages 11001-11006 ; 08885885 (ISSN) ; Rezaei Seresht, E ; Jafari, F ; Rabiei, S ; Sharif University of Technology
A highly chemoselective methodology is described for the N-methylation of functionalized anilines with dimethyl carbonate (MeOCO2Me, DMC) in the presence of ZrOCl2·8H2O. Dimethyl carbonate, which usually promotes methylation at T > 120 C and eventually under inert atmosphere, was activated in the presence of zirconium oxychloride for the desired transformation at 90 C under aerobic conditions. Aminophenols showed good reactivity in this transformation and produced the corresponding N-methylanilines, as the major products, with high selectivity. Catalyst reusability study confirmed that ZrOCl2·8H2O is a recyclable catalyst and its catalytic activity was remained unchanged at least after eight...
Oxido-peroxido molybdenum(VI) complexes in catalytic and stoichiometric oxidations, Article Coordination Chemistry Reviews ; Volume 257, Issue 7-8 , April , 2013 , Pages 1093-1121 ; 00108545 (ISSN) ; Haghdoost, M. M ; Bagherzadeh, M ; Sharif University of Technology
This review mainly discusses the application of oxido-peroxido Molybdenum(VI) complexes as catalysts or mediators in homogeneous or heterogeneous catalytic systems for oxidations of olefins, sulfides, alcohols, alkanes, and amines toward the synthesis of a variety of organic compounds, such as epoxides, sulfoxides, aldehydes and ketones, carboxylic acids, alcohols and nitroso compounds
Modeling of platinum extraction from used reforming catalyst in iodine solutions, Article ECS Transactions ; Volume 41, Issue 17 , 2012 , Pages 45-51 ; 19385862 (ISSN) ; 9781607683070 (ISBN) ; Baghallha, M ; Sharif University of Technology
Platinum extraction from spent reforming catalysts in iodine solutions under atmospheric pressure and at temperatures up to 95°C was previously investigated in our group. In this system, platinum is oxidized from the spent catalyst with tri-iodide. In some of the experiments, it was observed that platinum extraction peaked and then decreased. This indicates that a precipitation reaction slowly occurs that removes the dissolved Pt ions from the solution. Power-law rate equation for the Pt extraction to PtI6 2- and the precipitation of the dissolved platinum to PtI 4(s) was implemented to model the experimental Pt extraction data. The activation energies for the platinum dissolution reaction...
DFT investigations for "Fischer" esterification mechanism over silica-propyl-SO3H catalyst: Is the reaction reversible?, Article Computational and Theoretical Chemistry ; Volume 1071 , 2015 , Pages 27-32 ; 2210271X (ISSN) ; Fattahi, A ; Sharif University of Technology
For the first time, the mechanism of Fischer esterification between acetic acid and ethanol over silica-functionalized propylsulfonic acid (silica-propyl-SO3H) catalyst was explored by means of computational modeling techniques. For this purpose, 6-edge-atom cage-like cluster comprising Si-O-Si sequences has been selected to represent the surface of the catalyst. The results indicate that the reaction goes through concerted transition states. In all optimized structures no proton (H+) transfer occurs from catalyst to the substrates and the role of the catalyst is via the activation of the substrates through the formation of strong hydrogen bonds (H-bonds). Furthermore, the energetic diagram...
Preparation and study of bi-supported Ziegler-Natta catalyst with nano graphene oxide and magnesium ethoxide supports for polymerization of polyethylene, Article Polymer Science - Series B ; Volume 58, Issue 3 , 2016 , Pages 271-277 ; 15600904 (ISSN) ; Ramazani SaadatAbadi, A ; Khorasheh, F ; Baghalha, M ; Bahrami, H ; Sharif University of Technology
Maik Nauka-Interperiodica Publishing 2016
In this study, we have reported the preparation of bi-supported Ziegler-Natta catalysts using magnesium ethoxide and graphene oxide as support. The polymerization process was carried out in slurry phase using triisobutylaluminum as a co-catalyst.The XRD analysis of TiCl4/graphene oxide/Mg(OEt)2 catalyst demonstrated that the space between the layers of graphene oxide had increased to 0.2 nm.The catalyst was characterized by XPS, BET, BJH, SEM, and TGA. The catalyst activity was studied for various Al/Ti molar ratios, and the catalyst activity was optimum at Al/Ti molar ratio of 315. © 2016, Pleiades Publishing, Ltd
A simple, economical, and catalyst-free oxidation of thiols to disulfides, Article Journal of Sulfur Chemistry ; Volume 30, Issue 6 , 2009 , Pages 578-580 ; 17415993 (ISSN) ; Hashemi, M. M ; Sharif University of Technology
A simple, rapid, and highly efficient method for the preparation of symmetrical aliphatic, aromatic, and heteroaromatic disulfides is reported. Addition of NBS to an alkyl- or arylthiol under catalyst-free conditions in dichloromethane solution produces the corresponding disulfides in nearly quantitative yields