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Wednesday 21 August 2013

Direct synthesis of hydrogen peroxide in water in a continuous trickle bed reactor optimized to maximize productivity



Hydrogen peroxide direct synthesis was studied in continuous mode over a 5% wt Pd/C commercial catalyst in a Trickle Bed Reactor. The target of the study was to maximize the hydrogen peroxide production. The catalyst was uniformly diluted in quartz sand at different concentrations to investigate their effects on the direct synthesis.
The amount of catalyst and the distribution of the catalyst along the bed were optimized to obtain the highest possible yield. The distribution of the catalyst along the bed gave the possibility to significantly improve the selectivity and production of hydrogen peroxide (up to 0.5% under selected conditions). Higher production rate and selectivity were found when the catalyst concentration was decreased along the bed from the top to the bottom as compared to the uniformly dispersed catalyst.
The H2/Pd ratio was found to be an important parameter that has to be investigated in the hydrogen peroxide direct synthesis. The effect of a pretreatment of the catalyst with a solution of sodium bromide and phosphoric acid was studied; the results showed how a catalyst pretreatment can lead to a real green hydrogen peroxide synthesis in water. Some optimization guidelines are also provided.
Green Chem., 2013, 15,2502-2513
DOI: 10.1039/C3GC40811F, Paper


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Corresponding authors
a
Department of Chemical Engineering, Åbo Akademi University, Turku/Åbo, Finland
E-mail: bpierdom@abo.fi ;
Fax: +358 2 215 4479 ;
Tel: +358 2 215 4555
b
Department of Chemical Engineering and Environmental Technology, University of Valladolid, Valladolid, Spain
E-mail: jgserna@iq.uva.es
Hydrogen peroxide direct synthesis was studied in continuous mode over a 5% wt Pd/C commercial catalyst in a Trickle Bed Reactor.

Iodine-mediated arylation of benzoxazoles with aldehydes



A simple and efficient methodology for the arylation of benzoxazoles with aldehydes using iodine as the mediator has been developed. The reaction proceeded smoothly with a range of substrates to give the corresponding arylated products in moderate to good yields
Green Chem., 2013, 15,2365-2368
DOI: 10.1039/C3GC41027G, Communication


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Corresponding authors
a
Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore
E-mail: ygzhang@ibn.a-star.edu.sg ;
Fax: (+65) 6478-9020
A simple and efficient methodology for the arylation of benzoxazoles with aldehydes using iodine as the mediator has been developed