@article { ISI:000349088000020, title = {Oxidation catalysis by large trisoctahedral gold nanoparticles: Mind the step!}, journal = {Catalysis Today}, volume = {244}, year = {2015}, month = {APR}, pages = {177-183}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

To understand the origin of catalysis by gold and to probe the role of defects and interfaces, benchmark reactions namely CO oxidation and benzyl alcohol oxidation were carried out on supported trisoctahedral gold nanoparticles and on the inverse catalyst system. The sizes of these particles which are between 45 nm and 110 nm, are well beyond the quantum size regime and well above the optimum size range where gold is considered to be catalytically active. The periodic steps sites in contact with oxide support interface were able to promote the reaction. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {CO oxidation, Defects, Gold catalysis, Inverse catalysta, Steps and kinks}, issn = {0920-5861}, doi = {10.1016/j.cattod.2014.02.049}, author = {Sreedhala, S. and Sudheeshkumar, V. and Vinod, C. P.} } @article {45361, title = { One pot ligand exchange method for a highly stable Au-SBA-15 catalyst and its room temperature CO oxidation}, journal = {Chemical Communications}, volume = {54}, year = {2018}, month = {NOV}, pages = {12412-12415}, type = {Article}, abstract = {A modified deposition precipitation (DP) method has been developed to address a fundamental issue of supporting well dispersed Au nanoparticles on silica. Ammonium chloride (NH4Cl) plays an important role in in situ modifying the gold precursor (HAuCl(4)3H(2)O) solution allowing facile deposition of gold NPs in the channels of SBA-15. The Au-SBA-15 catalyst (2.8 wt\%) synthesized by this procedure showed 100\% conversion for CO oxidation at room temperature with excellent stability at room temperature and high temperature.}, issn = {1359-7345}, doi = {10.1039/c8cc06887a}, author = {Soni, Yogita and Kavya, I. and Ajithkumar, T. G. and Vinod, C. P.} } @article {45527, title = {Operando X-ray absorption spectroscopy study of the Fischer-Tropsch reaction with a Co catalyst}, journal = {Journal of Synchrotron Radiation}, volume = {26}, year = {2019}, month = {JAN}, pages = {137-144}, type = {Article}, abstract = {

This article describes the setting up of a facility on the energy-scanning EXAFS beamline (BL-09) at RRCAT, Indore, India, for operando studies of structure-activity correlation during a catalytic reaction. The setup was tested by operando X-ray absorption spectroscopy (XAS) studies performed on a Co-based catalyst during the Fischer-Tropsch reaction to obtain information regarding structural changes in the catalyst during the reaction. Simultaneous gas chromatography (GC) measurements during the reaction facilitate monitoring of the product gases, which in turn gives information regarding the activity of the catalyst. The combination of XAS and GC techniques was used to correlate the structural changes with the activity of the catalyst at different reaction temperatures. The oxide catalyst was reduced to the metallic phase by heating at 400 degrees C for 5h under H-2 at ambient pressure and subsequently the catalytic reaction was studied at four different temperatures of 240, 260, 280 and 320 degrees C. The catalyst was studied for 10h at 320 degrees C and an attempt has been made to understand the process of its deactivation from the XANES and EXAFS results.

}, keywords = {catalysis, EXAFS, Fischer-Tropsch reaction, in situ studies, structure-activity correlation, XANES}, issn = {1600-5775}, doi = {10.1107/S1600577518015588}, author = {Nayak, Chandrani and Jain, Preeti and Vinod, C. P. and Jha, S. N. and Bhattacharyya, D.} } @article {48292, title = {Oxidation of ethylene by Cu/TiO2: reducibility of Cu2+ in TiO2 as a possible descriptor of catalytic efficiency}, journal = {Catalysis Science \& Technology}, volume = {13}, year = {2023}, month = {APR}, pages = {2330-2339}, type = {Article}, abstract = {

Catalytic oxidation using non-noble metal-based catalysts is a promising approach to mitigate pollution due to VOCs in the air. In this work, mesoporous Cu/TiO2 catalysts containing different concentrations of Cu2+ (0.2, 1, 3, and 4 wt\% Cu w.r.t. Ti) were synthesized using the sol-gel technique. The catalysts were characterized using inductively coupled plasma-optical emission spectrometry, XRD, Raman spectroscopy, N-2 physisorption, cyclic voltammetry, H-2-TPR and electron microscopy to understand the structure and composition. The thermal catalytic gas phase oxidation of ethylene was studied by heating a mixture of ethylene (1.5 vol\%) and air (5.9 vol\%) in the presence of the Cu/TiO2 samples in the temperature range of 298 to 773 K. Cu/TiO2 showed a higher catalytic activity compared to TiO2 for the thermal oxidation of ethylene, indicating a strong promotion by doped copper ions. A volcanic behaviour in the catalytic activity was observed with different concentrations of Cu doping, with 1\% Cu/TiO2 showing a 99.5\% ethylene conversion at 673 K and 100\% selectivity to CO2. The activity of 1\% Cu/TiO2 remained consistent without deactivation for 24 h. At low dopant concentrations of Cu (0.2 and 1\% Cu/TiO2), the reduction of Cu2+ to Cu+ was observed. An interplay of oxygen vacancies (O-V), Cu+, Cu2+ and Ti4+ may be involved in controlling the activity. DRIFT studies indicated the formation of surface bidendate carbonate as a possible intermediate.

}, issn = {2044-4753}, doi = {10.1039/d2cy02170f}, author = {Rajendran, K. and Sharma, Mandeep and Jaison, Augustine and Ankitha, Menon and Tiwari, Ankit D. and Vinod, C. P. and Jagadeesan, Dinesh} }