@article {43020, title = {Nitrogen doping in oxygen-deficient Ca2Fe2O5: a strategy for efficient oxygen reduction oxide catalysts}, journal = {ACS Applied Materials and Interfaces}, volume = {8}, year = {2016}, month = {NOV}, pages = {34387{\textendash}34395}, doi = {10.1021/acsami.6b11718}, author = {Jijil, Chamundi P. and Lokanathan, Moorthi and Chithiravel, Sundaresan and Nayak, Chandrani and Bhattacharyya, Dibyendu and Jha, Shambhu Nath and Babu, P. D. and Kakade, Bhalchandra A. and Devi, R. Nandini} } @article {45738, title = {Convenient route for Au@Ti-SiO2 nanocatalyst synthesis and its application for room temperature CO oxidation}, journal = {Journal of Physical Chemistry C}, volume = {121}, year = {2017}, month = {MAR }, pages = {4946-4957}, type = {Article}, abstract = {

Small gold nanoparticles.of size less than 5 nm encapsulated inside titanium modified silica shell have been reported. Here, a modified sol-gel method, which is a one-step process, produces Au@Ti-SiO2 nanocatalyst with a good control of titanium loading. With a titanium loading of 0.9 and 2.2 wt \% in silica, unprecedented low temperature activity (full conversion) is observed for this catalyst for CO oxidation reaction compared to Au@SiO2 catalyst. A combination of optimum sized gold nanoparticles with a large amount of oxygen vacancies created due to Ti incorporation in silica matrix is considered to be the reason for this enhanced catalytic activity. The size of.gold nanoparticles is maintained even after high temperature pretreatments, which show the benefit of encapsulation. The effect of the various pretreatments on the catalytic activity has also been reported.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.6b10202}, author = {Soni, Yogita and Kumar, Anumol Erumpukuthical Ashok and Nayak, Chandrani and Deepak, Francis Leonard and Vinod, C. P.} } @article {44639, title = {Selective oxidation of cyclohexane to cyclohexanone using chromium oxide supported mesoporous MCM-41 nanospheres: probing the nature of catalytically active chromium sites}, journal = {ChemCatChem}, volume = {10}, year = {2018}, month = {AUG}, pages = {3291-3298}, abstract = {

Highly dispersed chromium oxide supported mesoporous MCM-41 nanosphere catalysts have been synthesized using a simple wet impregnation method. This work is devoted to a systematic study to reveal the active Cr sites in chromium oxide supported MCM-41 nanosphere catalysts for the selective oxidation of cyclohexane to cyclohexanone. To probe the nature of the active species, we synthesized 0.5-10wt\% Cr loaded catalysts and characterized them by using XRD, UV/Vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, extended X-ray absorption fine structure analysis, X-ray absorption near edge structure analysis, N-2 sorption analysis, FTIR spectroscopy, (SiNMR)-Si-29 spectroscopy, SEM, and TEM. The liquid-phase oxidation of cyclohexane to cyclohexanone (99\% selectivity) was performed under mild reaction conditions, and the results reveal clearly that the 5wt\% Cr loaded catalyst was optimum for the reaction. The initial composition of isolated Cr3+ species in the catalyst is the major factor that influences the enhanced activity for cyclohexane oxidation.

}, keywords = {chromium, heterogeneous catalysis, Nanostructures, Oxidation, supported catalysts}, issn = {1867-3880}, doi = {10.1002/cctc.201800309}, author = {Betsy, Kurisingal J. and Nayak, Chandrani and Lazar, Anish and Krishnan, Athira and Bhattacharyya, Dibyendu and Jha, Shambhu N. and Vinod, Chathakudath 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 {48765, title = {MnXWO4 nanostructure-based catalysts for single-step oxidation of cyclohexane and methane to oxygenates}, journal = {ACS Applied Nano Materials}, volume = {6}, year = {2023}, month = {APR}, pages = {7245-7258}, type = {Article}, abstract = {

Activation of the C-H bond in cyclohexane (CYH) and methane is a crucial step to obtain desirable oxygenated products using nanostructured catalyst and is a great challenge and an efficient route to mitigate the inauspicious effects of climate change. The active sites were identified using XRD, HR-TEM, SEM, N2 sorption analysis, TPR, Raman, XPS, TGA, in situ DRIFT, XAS, etc. In optimal reaction conditions, 46\% of CYH was converted into adipic acid (AA) on MnxWO4 nanostructures within 6 h. The recyclability test confirmed the catalyst heterogeneity, which revealed no appreciable loss of catalytic activity even after three consecutive reactions. In situ DRIFT study reveals that CYH is oxidized to cyclohexanone and cyclohexanol (KA oil) and is further oxidized to AA via carboxylate intermediates. DFT studies disclosed that MnOx species are responsible for the C-H activation of CYH, and the Mn2+/Mn3+ redox centers play a vital role in the absorption of KA oil to form AA. Herein, we demonstrated the significant role of the {\textquoteleft}{\textquoteleft}MnOx{\textquoteright}{\textquoteright} species and that adequate Lewis and Bronsted acidic sites, redox centers of (Mn2+/Mn3+), and lattice oxygen are accountable for the CYH conversion toward the AA. Additionally, we have reported the oxidation of methane to methanol (146 mu mole per gram of catalyst) in the presence of water at 75 degrees C without over-oxidation products.

}, keywords = {Adipic Acid, C-H bond activation, Cyclohexane oxidation, methane activation, MnOx chain, Redox center}, doi = {10.1021/acsanm.3c00319}, author = {Prabu, Marimuthu and Manikandan, Marimuthu and Samal, Pragnya Paramita and Gurrala, Lakshmi Prasad and Mekala, Siva Prasad and Archana, Ramakrishnan and Nayak, Chandrani and Bhattacharyya, D. and Jha, S. N. and Krishnamurty, Sailaja and Raja, Thirumalaiswamy} }