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Hari C. Bajaj - One of the best experts on this subject based on the ideXlab platform.

  • Solvent free synthesis of methyl palmitate over sulfated zirconia Solid Acid Catalyst
    Fuel, 2016
    Co-Authors: K. Saravanan, Beena Tyagi, Ram S. Shukla, Hari C. Bajaj
    Abstract:

    Abstract Sulfated zirconia (SZr) Solid Acid Catalyst, prepared by conventional precipitation technique was studied for esterification of palmitic Acid with methanol to synthesize methyl palmitate. The Catalyst exhibited 90% yield of methyl palmitate at 60 °C over 6 wt% Catalyst. The yield was significantly higher under solvent-free conditions than using hexane as a solvent. The alkyl palmitate yield was decreased with an increase in the alkyl chain of alcohol from methanol to n -butanol. The reaction followed pseudo-first order kinetics under the optimized reaction conditions with a reaction rate of 0.61 mmol h −1 , rate constant of 12.13 × 10 −3  h −1 and turn over frequency of 0.088 min −1 .

  • esterification of palmitic Acid with methanol over template assisted mesoporous sulfated zirconia Solid Acid Catalyst
    Applied Catalysis B-environmental, 2015
    Co-Authors: K. Saravanan, Beena Tyagi, Ram S. Shukla, Hari C. Bajaj
    Abstract:

    Abstract The esterification of palmitic Acid with methanol was studied over mesoporous sulfated zirconia (SZ) Solid Acid Catalyst, prepared by using CTAB cationic surfactant as a template. The effect of various reaction parameters has been studied. The Catalyst showed an excellent activity with 88–90% yield of methyl palmitate at 60 °C after 5–7 h. The reaction follows pseudo-first order kinetics under the reaction conditions studied with a reaction rate of 48.67 mmol h−1 g−1 and turnover frequency of 6.96 h−1. It is noteworthy that SZ Catalyst showed comparable activity to conventional Bronsted Acids namely H2SO4 and p-TSA; as well as it exhibited higher activity than various other heterogeneous Catalysts such as zeolites, ion-exchange resins and Acid clay.

Yanqin Wang - One of the best experts on this subject based on the ideXlab platform.

Fengbao Zhang - One of the best experts on this subject based on the ideXlab platform.

  • sulfonated graphene as water tolerant Solid Acid Catalyst
    Chemical Science, 2011
    Co-Authors: Junyi Ji, Guanghui Zhang, Hongyu Chen, Shulan Wang, Guoliang Zhang, Fengbao Zhang
    Abstract:

    Acid Catalysts are essential for various chemical reactions in the industrial hydrocarbon chemistry. Sulfonated carbon has shown promising application as a new, cheap and environmentally friendly Solid Acid Catalyst. In this study, we prepared the sulfonated graphene Acid Catalyst, and it was characterized by electron microscopy, Raman spectroscopy, Solid state 13C MAS NMR, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Catalytic hydrolysis of ethyl acetate shows that the sulfonated graphene has highly catalytic activity and can be repetitively used as a water-tolerant Solid Acid Catalyst.

  • Sulfonated graphene as water-tolerant Solid Acid Catalyst
    Chemical Science, 2011
    Co-Authors: Guanghui Zhang, Hongyu Chen, Shulan Wang, Guoliang Zhang, Fengbao Zhang, Xiaobin Fan
    Abstract:

    Acid Catalysts are essential for various chemical reactions in the industrial hydrocarbon chemistry. Sulfonated carbon has shown promising application as a new, cheap and environmentally friendly Solid Acid Catalyst. In this study, we prepared the sulfonated graphene Acid Catalyst, and it was characterized by electron microscopy, Raman spectroscopy, Solid state 13C MAS NMR, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Catalytic hydrolysis of ethyl acetate shows that the sulfonated graphene has highly catalytic activity and can be repetitively used as a water-tolerant Solid Acid Catalyst.

Jinfu Wang - One of the best experts on this subject based on the ideXlab platform.

  • reaction kinetics of biodiesel synthesis from waste oil using a carbon based Solid Acid Catalyst
    Chinese Journal of Chemical Engineering, 2011
    Co-Authors: Yuhui Liao, Jinfu Wang
    Abstract:

    Abstract The kinetics of simultaneous transesterification and esterification with a carbon-based Solid Acid Catalyst was studied. Two Solid Acid Catalysts were prepared by the sulfonation of carbonized vegetable oil asphalt and petroleum asphalt. These Catalysts were characterized on the basis of elemental analysis, Acidity site concentration, the Brunauer-Emmett-Teller (BET) surface area and pore size. The kinetic parameters with the two Catalysts were determined, and the reaction system can be described as a pseudo homogeneous catalyzed reaction. All the forward and reverse reactions follow second order kinetics. The calculated concentration values from the kinetic equations are in good agreement with experimental values.

  • synthesis of biodiesel from waste vegetable oil with large amounts of free fatty Acids using a carbon based Solid Acid Catalyst
    Applied Energy, 2010
    Co-Authors: Zeeshan Nawaz, Yuhui Liao, Dezheng Wang, Jinfu Wang
    Abstract:

    A carbon-based Solid Acid Catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt. This Catalyst was employed to simultaneously catalyze esterification and transesterification to synthesis biodiesel when a waste vegetable oil with large amounts of free fatty Acids (FFAs) was used as feedstock. The physical and chemical properties of this Catalyst were characterized by a variety of techniques. The maximum conversion of triglyceride and FFA reached 80.5 wt.% and 94.8 wt.% after 4.5 h at 220 °C, when using a 16.8 M ratio of methanol to oil and 0.2 wt.% of Catalyst to oil. The high catalytic activity and stability of this Catalyst was related to its high Acid site density (-OH, Bronsted Acid sites), hydrophobicity that prevented the hydration of -OH species, hydrophilic functional groups (-SO3H) that gave improved accessibility of methanol to the triglyceride and FFAs, and large pores that provided more Acid sites for the reactants.

  • synthesis of biodiesel from a model waste oil feedstock using a carbon based Solid Acid Catalyst reaction and separation
    Bioresource Technology, 2010
    Co-Authors: Zeeshan Nawaz, Yuhui Liao, Qiang Zhang, Dezheng Wang, Jinfu Wang
    Abstract:

    A Solid Acid Catalyst that can keep high activity and stability is necessary when low cost feedstocks are utilized for biodiesel synthesis because the reaction medium contains a large amount of water. Three Solid Acid Catalysts were prepared by the sulfonation of carbonized vegetable oil asphalt and petroleum asphalt. The structure of these Catalysts was characterized by a variety of techniques. A new process that used the coupling of the reaction and separation was employed, which greatly improved the conversion of cottonseed oil (triglyceride) and free fatty Acids (FFA) when a model waste oil feedstock was used. The vegetable oil asphalt-based Catalyst showed the highest catalytic activity. This was due to the high density and stability of its Acid sites, its loose irregular network, its hydrophobicity that prevented the hydration of –OH species, and large pores that provided more Acid sites for the reactants.

  • synthesis of biodiesel from cottonseed oil and methanol using a carbon based Solid Acid Catalyst
    Fuel Processing Technology, 2009
    Co-Authors: Qing Shu, Qiang Zhang, Zeeshan Nawaz, Dezheng Wang, Jinfu Wang
    Abstract:

    A carbon-based Solid Acid Catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt and used to catalyze the transesterification of methanol with cottonseed oil. This Catalyst was characterized by scanning electron microscopy/energy dispersive spectroscopy, BET surface area and pore size measurement, thermogravimetry analysis and Fourier transform infrared spectroscopy. The sulfonated multi-walled carbon nanotubes (s-MWCNTs) was also prepared and used to catalyze the same transesterification as the asphalt Catalyst. The asphalt-based Catalyst shows higher activity than the s-MWCNTs for the production of biodiesel, which may be correlated to its high Acid site density, its loose irregular network and large pores can provide more Acid sites for the reactants. The conversion of cottonseed oil 89.93% was obtained (using the asphalt-based Catalyst) when the methanol/cottonseed oil molar ratio was 18.2, reaction temperature at 260 °C, reaction time 3.0 h and Catalyst/cottonseed oil mass ratio of 0.2%. Also, it can be re-used. The sulfonated polycyclic aromatic hydrocarbons provide an electron-withdrawing function to keep the Acid site stable. The Catalyst can substantially reduce energy consumption and waste generation in the production of biodiesel.

John Meurig Thomas - One of the best experts on this subject based on the ideXlab platform.

  • Probing the Evolution of Water Clusters During Hydration of the Solid Acid Catalyst H-ZSM-5
    Philosophical Magazine, 2009
    Co-Authors: Kenneth D. M. Harris, John Meurig Thomas
    Abstract:

    A technique developed recently for in situ Solid-state 1H NMR studies of adsorption processes is applied to probe hydration of the Solid Acid Catalyst H-ZSM-5, yielding information on the interaction between the adsorbed water molecules and Brønsted Acid sites on the H-ZSM-5 host material. Quantitative analysis of the results from the in situ experiment allows the average size of water clusters associated with the Brønsted Acid sites to be determined directly, and suggests that there is a preference to form clusters comprising 5 – 6 water molecules. The in situ 1H NMR data also provide insights on kinetic aspects of the adsorption process.

  • In situ Solid-state 1H NMR studies of hydration of the Solid Acid Catalyst ZSM-5 in its ammonium form
    Solid State Nuclear Magnetic Resonance, 2009
    Co-Authors: Mingcan Xu, Kenneth D. M. Harris, John Meurig Thomas
    Abstract:

    Hydration of the ammonium form of the Solid Acid Catalyst ZSM-5 is investigated by applying a technique that has been developed recently for carrying out in situ Solid-state NMR studies of adsorption processes. From 1H MAS NMR spectra recorded as a function of time and temperature during the hydration process, insights are established on the nature of the interaction between the adsorbed water molecules and the ammonium cations in the ZSM-5 material. The change in isotropic chemical shift for the ammonium cations is consistent with the formation of N–H⋯O hydrogen bonding with the water molecules. Studies of the adsorption of deuterated water, and dehydration of the hydrated material, are also reported.

  • On the Nature of Water Bound to a Solid Acid Catalyst
    Science, 1996
    Co-Authors: Luis J. Smith, John Meurig Thomas, Anthony K. Cheetham, Russell E. Morris, Leonardo Marchese, Paul A. Wright, Jiesheng Chen
    Abstract:

    The nature of the species formed when water interacts with Bronsted Acid sites in a microporous Solid Acid Catalyst, HSAPO-34, was studied by powder neutron diffraction and infrared spectroscopy. Previous infrared and computational studies had failed to unambiguously establish whether water is protonated to form hydronium (H3O+) ions or is merely hydrogen-bonded to Acid sites inside the zeolite. Our experiments clearly showed that both species are present: An H3O+ ion is found in the eight-ring channel of the zeolite and a second water molecule is hydrogen-bonded to an Acid site on the six-ring.