Role of size and pretreatment of Pd particles on their behaviour in the direct synthesis of H2O2

Role of size and pretreatment of Pd particles on their behaviour in the direct synthesis of H2O2

Salvatore Abate;Katia Barbera;Gabriele Centi;Gianfranco Giorgianni;Siglinda Perathoner

【期刊名称】《天然气化学（英文版）》 【年(卷),期】2016(025)002

【摘要】Two families of catalysts,based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes,are studies in the direct synthesis of H2O2.They are prepared by depositing Pd in two ways:(i) reduction with N2H4 in an ultrasonic bath and (ii) by impregnation-deposition.The

first

preparation

leads

to

larger

particles,with average size of around 11 nm,while the second preparation leads to smaller particles,with average size around 4 nm.The catalytic membranes were tested as prepared,after thermal treatment in air and after further pre-reduction with H2 in mild (100℃) conditions.Samples were characterized by TEM,CO-chemisorption monitored by DRIFTS method and TPR,while catalytic tests have been performed in a semi-batch recirculation membrane reactor.Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network.Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion,even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity