@article { ISI:000246754200022, title = {Generation of hydrogen peroxide via the selective reduction of oxygen by hydrazine sulfate over Br-promoted Pd/Al2O3 catalyst in an aqueous medium at ambient conditions}, journal = {Applied Catalysis A-General}, volume = {323}, year = {2007}, month = {APR}, pages = {202-209}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The in situ generation of H2O2 via the selective reduction of OZ by hydrazine sulfate (in an aqueous medium) has been thoroughly investigated over the Br-promoted Pd(or PdO)/Al2O3 catalyst. The influence of the following factors have been addressed in this study: (a) Br concentration (in the reaction medium or incorporated in the catalyst); (b) reaction conditions (viz. reaction time, temperature); (c) concentrations of reducing agent and phosphoric acid in the reaction medium. Decomposition of N2H4 (from NH4-H2SO4) and its reaction with H2O2 under similar reaction conditions (in the absence of O-2) have also been studied. H2O2, which is an intermediate product of the O-2 reduction, is involved in further consecutive reactions. It can be converted to water via its decomposition and/or reaction with the unconverted NZH(4). In the presence of Br promoter, the later (reaction with unconverted N2H4) is more dominant. Both the consecutive reactions are drastically retarded in the presence of protons and Br promoter. A plausible reaction mechanism has been proposed for illustrating the role of the protons and Br promoter in the selective formation of H2O2 in the O-2 reduction process. (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {brominated Pd/Al2O3 catalyst, hydrazine sulfate, Hydrogen peroxide, in situ H2O2 generation, oxygen reduction, Pd/Al2O3 catalyst}, issn = {0926-860X}, doi = {10.1016/j.apcata.2007.02.014}, author = {Choudhary, Vasant R. and Jana, Prabhas and Samanta, Chanchal} } @article { ISI:000250256700004, title = {In situ generation of hydrogen peroxide from reaction of O-2 with hydroxylamine from hydroxylammonium salt in neutral aqueous or non-aqueous medium using reusable Pd/Al2O3 catalyst}, journal = {Catalysis Communications}, volume = {8}, number = {11}, year = {2007}, month = {NOV}, pages = {1578-1582}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

In situ generation of H2O2 with high yield can be accomplished by reacting 02 with NH2OH from hydroxylammonium salt [NH2OH.HCl or (NH2OH)(2) . H2SO4] in a neutral aqueous medium using a reusable heterogeneous Pd (1.0 wt\%)/Al2O3 catalyst, even at low temperature (10 degrees C), with the formation of harmless by-products (viz. N-2 and water). The presence of KCl or KBr in the medium has beneficial effect. The H2O2 generation is strongly influenced by the pH of medium, reaction period and temperature; best results are obtained at the optimum pH and reaction medium. (c) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Hydrogen peroxide, hydroxylamine, Hydroxylammonium salt, in situ H2O2 generation, oxygen, Pd/AlO3 catalyst}, issn = {1566-7367}, doi = {10.1016/j.catcom.2007.01.003}, author = {Choudhary, Vasant R. and Jana, Prabhas} } @article { ISI:000245961800014, title = {Reduction of oxygen by hydroxylammonium salt or hydroxylamine over supported Au nanoparticles for in situ generation of hydrogen peroxide in aqueous or non-aqueous medium}, journal = {Catalysis Communications}, volume = {8}, number = {5}, year = {2007}, month = {MAY}, pages = {811-816}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Reaction of O-2 with hydroxylamine or its salts over a number of supported gold catalysts containing An nanoparticles (at 10-70 degrees C) has been studied at atmospheric pressure for the in situ generation of H2O2 (required for organic oxidation reactions in the synthesis of fine/specialty chemicals) in aqueous (water) or non-aqueous medium. Hydrogen peroxide in high yields with harmless by-products (viz. water and nitrogen) can be generated in situ by the reduction Of O-2 by hydroxylammonium sulfate (or chloride) or hydroxylamine using the supported gold catalysts particularly Au/Gd2O3, Au/La2O3 and Au/MgO, in aqueous (water) or non-aqueous (viz. methanol) medium at close to ambient conditions. The reduction of O-2 by hydroxylammonium salt to H2O2, however, requires preneutralization of the salt by alkali; in the absence of the neutralization, only water is formed in the reaction. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Au Nanoparticles, Au/Gd2O3, Au/La2O3, Au/MgO, Hydrogen peroxide, hydroxylamine, hydroxylammonium salts, in situ H2O2 generation}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.08.041}, author = {Choudhary, Vasant R. and Jana, Prabhas and Bhargava, Suresh Kumar} }