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    Preparation of sorbitan stearate

    , Article 2nd International Multi-Conference on Engineering and Technological Innovation, IMETI 2009, Orlando, FL, 10 July 2009 through 13 July 2009 ; Volume 1 , 2009 , Pages 81-85 ; 193427268X (ISBN); 9781934272688 (ISBN) Amin Mahalati, A. R ; Alemzadeh, I ; Vossoughi, M ; Inter-American Organization for Higher Education (IOHE); International Institute of Informatics and Systemics (IIIS); Journal of Systemics, Informatics and Cybernetics (JSCI) ; Sharif University of Technology
    International Institute of Informatics and Cybernetics, IIIC  2009
    The present paper relates to an improved method for making surfactant esters, especially sorbitan monostearate and tristearate. Sorbitan esters of fatty acid, stéarate are derived from a reaction between sorbitan and fatty acid. Method of sorbitan ester production needs addition of catalyst. Sorbitan stéarate production was studied using chemical catalyst. Two steps process leading sorbitan production under atmospheric and vacuum pressure with acid catalyst resulted dehydrated product at optimal residence time of 195 min at 180°C for atmospheric conditions and optimalresidence time of 150 min at the same temperature respectively. Sorbitan stearate production was studied by utilizing sorbitan... 

    Oxovanadium(IV) complexes as homogeneous catalyst-aerobic epoxidation of olefins

    , Article Applied Catalysis A: General ; Volume 278, Issue 2 , 2005 , Pages 263-267 ; 0926860X (ISSN) Mohebbi, S ; Boghaei, D. M ; Sarvestani, A. H ; Salimi, A ; Sharif University of Technology
    The novel N2O2 unsymmetrical tetradentate Schiff bases complexes are used as catalysts for the selective aerobic oxidation of cyclohexene. In general, conversion percentages decrease with increasing ΔEp and decreasing Eredox 0′. Catalytic activity increases with decrease of the number of electron-donating groups and the catalytic selectivity varies according to the types of substituents in the ligands. The catalytic system described here is an inexpensive method for selective oxidation of olefins, with advantages of high activity, selectivity, re-usability and short reaction times. Analysing GC and redox potential results shows a moderate correlation between selectivity and activity. © 2004... 

    The effect of variable catalyst loading in electrodes on PEM fuel cell performance

    , Article 3rd International Conference on Fuel Cell Science, Engineering, and Technology, 2005, Ypsilanti, MI, 23 May 2005 through 25 May 2005 ; 2005 , Pages 145-152 ; 0791837645 (ISBN); 9780791837641 (ISBN) Roshandel, R ; Farhanieh, B ; Sharif University of Technology
    American Society of Mechanical Engineers  2005
    Catalyst layers are one the important parts of the PEM fuel cells as they are the main place for electrochemical reaction taking place in anode and cathode of the cells. The amount of catalyst loading of this layer has a large effect on PEM fuel cell performance. Non-uniformity of reactant concentration could lead to a variation of current density in anode and cathode catalyst layer. The main reason for this phenomenon is porosity variation due to two effects: 1. compression of electrode on the solid landing area and 2. Water produced at the cathode side of diffusion layer. In this study the effect of variable current density in anode and cathode electrode on cell performance is... 

    Synthesis of Platinum Nanoparticles and Study on its Application as a Catalyst and an Adsorbent of the Radioactive Elements

    , M.Sc. Thesis Sharif University of Technology Mehdizadeh, Sofia (Author) ; Outokesh, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor) ; Sadjadi, Sodeh (Co-Advisor)
    The present study was aimed at investigating the use of platinum and platinum nanoparticles stabilized on zeolite as catalyst for the reduction reaction of p-nitrotoluene as one of the dangerous pollutants. The adsorption properties of platinum based on zeolite have been studied for some heavy metals. Monodispersed platinum nanoparticles were synthesized through reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone (PVP) as a stabilizer, and then were immobilized on four types of zeolites. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. In order to investigate the catalytic properties, operating... 

    Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst [electronic resource]

    , Article Reactive and Functional Polymers ; 01/2002; 51(1):49-53 Pourjavadi, A. (Ali) ; Soleimanzadeh, B ; Marandi, G. B
    γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity  

    On the formation of SWCNTs and MWCNTs by Arc-discharge in aqueous solutions: the role of iron charge and counter ions [electronic resource]

    , Article Journal of Fullerenes, Nanotubes and Carbon Nanostructures ; 2011, Volume 19, Issue 4, Pages 317-328 Gheytani, S ; Shervin, Sh ; Simchi, A. (Abdolreza) ; Sharif University of Technology
    Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were synthesized in aqueous solutions containing FeCl2, FeCl3, FeSO4 and Fe2(SO4)3. The effects of iron charge and the counter ions on the formation of carbon nanotubes (CNTs) were investigated. Thermogravimetric (TG) analysis indicated that carbon multilayer structures including CNTs and multishell graphite particles were formed in deionized (DI) water without the iron precursor. SWCNTs were also synthesized in the presence of the iron ions. It was also found that the mole ratio of [Fe2+]/[Fe3+] in the solution has a significant influence on the purity of CNTs and the process yield. The highest yield was... 

    Functionalized poly(amidoamine) dendrimer as a strong ionic Brønsted acid organocatalyst for protection/deprotection of aldehydes

    , Article Phosphorus, Sulfur and Silicon and the Related Elements ; Vol. 189, issue. 12 , 2014 , pp. 1794-1801 ; ISSN: 10426507 Pourjavadi, A ; Hosseini, S. H ; Sharif University of Technology
    Poly(amidoamine) dendrimer (PAMAM) was successfully functionalized by chlorosulfonic acid to form an strong ionic acid catalyst. The resulting polymeric catalyst was shown to be an efficient catalyst for the synthesis of 1,1-diacetyl from aldehydes under free solvent conditions at room temperature. Also, the deprotection of the resulting aldehydes was investigated under catalytic conditions. The Hammett acidity function of catalyst showed that catalyst is a strong Brønsted acid. Due to the multi-functional nature of PAMAM, the catalyst has high loading level of acidic protons  

    Investigating the effect of calcination repetitions on the lifetime of Co/γ-Al2O3 catalysts in Fischer-Tropsch synthesis utilising the precursor's solution affinities

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 44, Issue 2 , 2013 , Pages 205-213 ; 18761070 (ISSN) Hemmati, M. R ; Kazemeini, M ; Khorasheh, F ; Zarkesh, J ; Sharif University of Technology
    Cobalt-based catalysts were prepared on different alumina supports, and their behaviour for different Fischer-Tropsch synthesis (FTS) conditions assessed. Although Co/γ-Al2O3 is a well-known FTS catalyst, its durability ought to be improved to make the industrial process economically feasible. Here calcination repetitions effects on the catalyst lifetime were examined utilising reactor tests and characterisation techniques including XRD, TPR, ICP and N2 porosimetry. Results revealed that fewer calcination repetitions improved catalyst activity and selectivity. Based upon the XRD results, these findings appeared to be due to the improved size of cobalt crystals on the pore surfaces. These... 

    Preparation and characterization of Co-Mo catalyst supported on CNT coated cordierite monoliths utilized for naphta HDS process

    , Article Procedia Engineering ; Volume 42 , 2012 , Pages 1484-1492 ; 18777058 (ISSN) Soghrati, E ; Kazemeini, M ; Rashidi, A. M ; Jafari Jozani, Kh ; Sharif University of Technology
    In the present study, an acid treatment of the cordierite monolith followed by coating of the CNT onto it by means of catalytic chemical-vapor deposition (CCVD) of methane over CoMo catalyst was performed. The resulting material utilized as the supports for the HDS catalyst onto which was deposited Co and Mo species. The as-prepared samples were characterized by the BET, XRD, FESEM and ICP-MS techniques. BET experiments showed that a significant increase in specific surface area and pore volume was observed, and a suitable pore size distribution was obtained after acid pretreatment. The FESEM images of CNT coated monolith showed that CNTs were distributed uniformly on the surface of monolith... 

    Magnetic nanoparticles coated by acidic functionalized poly(amidoamine) dendrimer: Effective acidic organocatalyst

    , Article Catalysis Communications ; Volume 28 , 2012 , Pages 86-89 ; 15667367 (ISSN) Pourjavadi, A ; Hosseini, S. H ; Hosseini, S. T ; Aghayeemeibody, S. A ; Sharif University of Technology
    A novel magnetic Br∅nsted acid catalyst was synthesized based on growing poly(amidoamine) dendrimers on the surface of magnetic nanoparticles. After the dendronizing process, the MNP coated PAMAM was functionalized by chlorosulfuric acid to form an acid catalyst. Because of dendrimer coating of MNPs, catalyst shows good loading level of acidic groups on the surface. Also zwitterion nature of catalyst surface improves the catalytic activity. This new catalyst is proven to be highly effective in the synthesis of α-aminophosphonate compounds in a green way  

    Multi-Layer functionalized poly(ionic liquid) coated magnetic nanoparticles: Highly recoverable and magnetically separable brønsted acid catalyst

    , Article ACS Catalysis ; Volume 2, Issue 6 , 2012 , Pages 1259-1266 ; 21555435 (ISSN) Pourjavadi, A ; Hosseini, S. H ; Doulabi, M ; Fakoorpoor, S. M ; Seidi, F ; Sharif University of Technology
    A functionalized poly(ionic liquid) coated magnetic nanoparticle (Fe 3O 4@PIL) catalyst was successfully synthesized by polymerization of functionalized vinylimidazolium in the presence of surface modified magnetic nanoparticles. The resulting heterogeneous catalyst is shown to be an efficient acidic catalyst for synthesis of 1,1-diacetyl from aldehydes under solvent free conditions and room temperature in high yields. Also, the catalyst shows good activity for the deprotection reaction of acylals. After completion of reaction, the catalyst was simply recovered by an external conventional magnet and recycled without significant loss in the catalytic activity. Because of the polymer layers... 

    Simple and highly efficient catalyst- and waste-free ring opening of epoxides with Na2S in water

    , Article Monatshefte fur Chemie ; Volume 141, Issue 3 , 2010 , Pages 323-326 ; 00269247 (ISSN) Azizi, N ; Akbari, E ; Ebrahimi, F ; Saidi, M. R ; Sharif University of Technology
    Water was found to be a highly efficient and green catalyst and solvent for ring-opening reaction of epoxides with Na2S at room temperature to give substituted bis(hydroxyethyl)thioethers in high yields  

    Synthesis, characterization, and catalytic activity of supported molybdenum Schiff base complex as a magnetically recoverable nanocatalyst in epoxidation reaction

    , Article Journal of Coordination Chemistry ; Volume 69, Issue 4 , 2016 , Pages 668-677 ; 00958972 (ISSN) Moradi Shoeili, Z ; Zare, M ; Bagherzadeh, M ; Ozkar, S ; Akbayrak, S ; Sharif University of Technology
    Taylor and Francis Ltd  2016
    A heterogeneous nanocatalyst was prepared via covalent anchoring of dioxomolybdenum(VI) Schiff base complex on core-shell structured Fe3O4@SiO2. The properties and the nature of the surface-fixed complex have been identified by a series of characterization techniques such as SEM, EDX, XRD, TGA, FT-IR, and VSM. The synthesized hybrid material was an efficient nanocatalyst for selective oxidation of olefins to corresponding epoxides with t-BuOOH in high yields and selectivity. The catalyst could be conveniently recovered by applying an external magnetic field and reused several times without significant loss of efficiency. © 2016 Taylor and Francis  

    Magnetic starch nanocomposite as a green heterogeneous support for immobilization of large amounts of copper ions: Heterogeneous catalyst for click synthesis of 1,2,3-triazoles

    , Article RSC Advances ; Volume 6, Issue 23 , 2016 , Pages 19128-19135 ; 20462069 (ISSN) Pourjavadi, A ; Motamedi, A ; Hosseini, S. H ; Nazari, M ; Sharif University of Technology
    Royal Society of Chemistry 
    A new magnetic heterogeneous copper catalyst was prepared by immobilization of copper ions onto a cross-linked polymeric nanocomposite composed of starch grafted polyacrylamide and functionalized Fe3O4 magnetic nanoparticles. The resulting support was loaded with large amounts of copper ions (1.6 mmol g-1). The prepared catalyst is highly active in Huisgen 1,3-dipolar cycloaddition reactions of different azides and alkynes at low catalyst amounts. Various corresponding 1,2,3-triazoles were produced with high yields in mild conditions. The catalyst was easily recovered and reused for ten cycles of reaction and no significant loss of catalytic activity was observed  

    Separation and recovery of cobalt catalyst from wastewater of PTA unit

    , Article Reviews in Inorganic Chemistry ; Volume 29, Issue 3 , 2009 , Pages 171-179 ; 01934929 (ISSN) Sajadi, S. A. A ; Abdolahifar, A ; Jafarbegloo, M ; Sharif University of Technology
    The goal of this work is separation and recovery of catalyst residue in wastewater and byproducts of PTA (poly terephetalic acid) unit. Catalyst recovery consists in separating the maximum amount of catalyst and changing the same into valuable compounds. The PTA unit uses cobalt catalyst for oxidation reactions. The byproducts, which contain catalyst, were burned. In the case of metal oxide recovery in the ashes of waste materials, we could solve the problem of the Petrochemical Company. This new method may help us to recover catalyst from wastewater in PTA unit, after which small amounts of ions may be absorbed on a column filled with special absorbent, in such a way that the wastewater... 

    Naphtha HDS over Co-Mo/Graphene catalyst synthesized through the spray pyrolysis technique

    , Article Journal of Analytical and Applied Pyrolysis ; Volume 123 , 2017 , Pages 144-151 ; 01652370 (ISSN) Hajjar, Z ; Kazemeini, M ; Rashidi, A ; Soltanali, S ; Bahadoran, F ; Sharif University of Technology
    Elsevier B.V  2017
    Co-Mo/Graphene composite synthesized for the first time through the spray pyrolysis method and applied as an HDS catalyst to produce a sulfur free Naphtha feed. The major advantage of the spray pyrolysis technique was its concurrent capability of the in-situ and simultaneous Co-Mo deposition upon the graphene. The produced material was characterized through the XRD, BET-BJH, FTIR and Raman spectroscopy as well as; the NH3-TPD, TPR, TEM and FESEM techniques. The prepared catalyst showed unique properties such as; high degree of total acidity of 5.1 (vs. the usual 0.2–2.0) mmole NH3/g-cat and a relatively high surface area of 705 vs. 189 m2/g of the commercial material. Furthermore, the... 

    In-situ preparation and characterization of ultra-high molecular weight polyethylene/diamond nanocomposites using bi-supported Ziegler-Natta catalyst: effect of nanodiamond silanization

    , Article Materials Today Communications ; Volume 14 , March , 2018 , Pages 53-64 ; 23524928 (ISSN) Haddadi, S. A ; Ramezani Saadatabadi, Ahmad ; Amini, M ; Kheradmand, A ; Shsrif University of Technology
    Elsevier Ltd  2018
    In this study, reinforcement of ultra-high molecular weight polyethylene (UHMWPE) was investigated using the sol-gel surface modified diamond nanoparticles (NDs). Nanocomposite samples were synthesized via in-situ polymerization using bi-supported Ziegler-Natta catalyst. Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle measurements proved the proper silanization (∼1.9%) of NDs. Characterization of the catalysts revealed decrease in the activity of catalysts in presence of NDs which were responsible for the lower average molecular weight of the samples. Field emission scanning electron microscopy revealed an improved dispersion of the modified NDs in... 

    Catalyst-Free three-component synthesis of spirobenzimidazolidines bearing an indole scaffold

    , Article Synlett ; Volume 29, Issue 17 , 2018 , Pages 2301-2305 ; 09365214 (ISSN) Matloubi Moghaddam, F ; Moafi, A ; Zamani, Z ; Daneshfar, M ; Sharif University of Technology
    Georg Thieme Verlag  2018
    An efficient catalyst-free one-pot three-component reaction was developed for the synthesis of a new family of N- A nd S-containing spirocyclic compounds. Various derivatives of spirobenzimidazolidine containing an indole scaffold were synthesized for the first time in a modestly toxic solvent and under mild reaction conditions. The reaction times were of the order of several minutes, and all the products were obtained in moderate to high yields (overall yields 58-80%). © Georg Thieme Verlag Stuttgart New York  

    A facile and convenient synthesis of 3-alkylidene-oxindoles bearing tetrahydropyrazine scaffold under catalyst-free conditions

    , Article Heteroatom Chemistry ; Volume 29, Issue 2 , March , 2018 ; 10427163 (ISSN) Matloubi Moghaddam, F ; Moafi, A ; Sharif University of Technology
    Wiley-Blackwell  2018
    A facile and efficient synthesis of 2-oxindole derivatives bearing tetrahydropyrazine scaffold has been developed. Using water as solvent without any additional acid or metal catalyst, easy work up and high yield of products are the main advantages of this protocol. © 2018 Wiley Periodicals, Inc  

    Synthesis and characterization of molybdenum complex supported on magnetic and non-magnetic supports: comparing their catalytic activity, selectivity, and reusability

    , Article Journal of the Iranian Chemical Society ; Volume 16, Issue 4 , 2019 , Pages 673-685 ; 1735207X (ISSN) Bagherzadeh, M ; Balali, M ; Haghdoost, M. M ; Keypour, H ; Sharif University of Technology
    Springer Verlag  2019
    A molybdenum complex was immobilized on Schiff-base-modified magnetic and non-magnetic particles by covalent linkage. The characterizations of the obtained materials were carried out by means of TG–DTG, SEM, TEM, VSM, XPS, IR, and Raman microprobe techniques. All of them exhibited efficient activities in the oxidation of sulfides to sulfoxides by urea hydrogen peroxide oxidant. The advantages and disadvantages of these catalysts are discussed in detail. Molybdenum complex immobilized on silica bead can be recycled and recovered by simple filtration, but it demonstrated low activity in catalytic oxidation reaction. Immobilization on nano-SiO 2 leads to the formation of nanocatalyst having...