Vasant R Choudhary
Articles written in Journal of Chemical Sciences
Volume 115 Issue 4 August 2003 pp 281-286
Vasant R Choudhary Abhijeet J Karkamkar
Temperature-programmed desorption (TPD) of water and ammonia over ZrO2 and sulphated ZrO2 prepared by different methods has been investigated for measuring strong acidity and acidity distribution on sulphated zirconia-type solid super-acid catalysts. The TPD of water provides a simple reliable method for this purpose because of the high stability of water molecules under redox conditions
Volume 115 Issue 4 August 2003 pp 287-298
Low temperature complete combustion of dilute propane over Mn-doped ZrO2 (cubic) catalysts
Vasant R Choudhary Subhabrata Banerjee Suryakant G Pataskar
Combustion of dilute propane (0.9 mol%) over Mn-doped ZrO2 catalysts prepared using different precipitating agents (viz. TMAOH, TEAOH, TPAOH, TBAOH and NH4OH), having different Mn/Zr ratios (0.05—0.67) and calcined at different temperatures (500—800°C), has been thoroughly investigated at different temperatures (300—500°C) and space velocities (25,000–100,000 cm3 g−1 h−1) for controlling propane emissions from LPG-fuelled vehicles. Mn-doped ZrO2 catalyst shows high propane combustion activity, particularly when its ZrO2 is in the cubic form, when its Mn/Zr ratio is close to 0.2 and when it is prepared using TMAOH as a precipitating agent and calcined at 500—600°C. Pulse reaction of propane in the absence of free-O2 over Mn-doped ZrO2 (cubic) and Mn-impregnated ZrO2 (monoclinic) catalysts has also been investigated for studying the relative reactivity and mobility of the lattice oxygen of the two catalysts. Both reactivity and mobility of the lattice oxygen of Mn-doped ZrO2 are found to be much higher than that of Mnimpregnated ZrO2. Propane combustion over Mn-doped ZrO2 catalyst involves a redox mechanism
Volume 116 Issue 3 May 2004 pp 175-177
Acylation of aromatic alcohols and phenols over InCl3/montmorillonite K-10 catalysts
Vasant R Choudhary Kailash Y Patil Suman K Jana
Montmorillonite K-10 clay supported InCl3 is a highly active catalyst for the acylation of aromatic alcohols and phenols with different acyl chlorides. This catalyst can be reused in reactions a number of times without very significant loss of catalytic activity
Volume 117 Issue 6 November 2005 pp 635-639
Vasant R Choudhary Rani Jha Pankaj A Choudhari
Fe-Mg-hydrotalcite (Mg/Fe = 3) anionic clay with or without calcination (at 200–800‡C) has been used for the benzylation of toluene and other aromatic compounds by benzyl chloride. Hydrotalcite before and after its calcination was characterized for surface area, crystalline phases and basicity. Both the hydrotalcite, particularly after its use in the benzylation reaction, and the catalyst derived from it by its calcination at 200–800‡C show high catalytic activity for the benzylation of toluene and other aromatic compounds. The catalytically active species present in the catalyst in its most active form are the chlorides and oxides of iron on the catalyst surface.
Volume 118 Issue 3 May 2006 pp 261-267
Non-catalytic pyrolysis of ethane to ethylene in the presence of CO2 with or without limited O2
Vasant R Choudhary Kartick C Mondal Shafeek A R Mulla
Influence of the presence of CO2, which is a mild oxidant, on the performance of the thermal cracking of ethane to ethylene in the absence or presence of limited O2 at different temperatures (750–900‡C), space velocities (1500–9000 h-1) and CO2/C2H6 and O2/C2H6 mole ratios (0–2.0 and 0–0.3 respectively) has been investigated. In both the presence and absence of limited O2, ethane conversion increases markedly because of the presence of CO2, indicating its beneficial effect on the ethane to ethylene cracking. The increased ethane conversion is, however, not due to the oxidation of ethane to ethylene by CO2; the formation of carbon monoxide in the presence of CO2 is found to be very small. It is most probably due to the activation of ethane in the presence of CO2.
Volume 124 Issue 4 July 2012 pp 835-839
Vasant R Choudhary Deepa K Dumbre Vijay S Narkhede
A number of hydrotalcite (Mg-Al, Mn-Al, Co-Al, Ni-Al, Mg-Fe, Mg-Cr and Cu-Al) catalysts, with or without MnO$^{−1}_4$-exchange, were evaluated for their performance in the solvent-free oxidation of benzaldehyde to benzoic acid by tert-butyl hydroperoxide under reflux in the absence of any solvent. The MnO$^{−1}_4$-exchanged Mg-Al-hydrotalcite (Mg/Al = 10) showed high activity in the oxidation of different aromatic and aliphatic aldehydes to their corresponding acids and also showed excellent reusability in the oxidation process which is environmental-friendly.
Volume 135, 2023
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