Influence of Pt particle size and support type on the aqueous-phase reforming of glycerol

The catalytic conversion of glycerol to hydrogen by aqueous-phase reforming (APR) on several platinum based catalysts was studied. Catalysts prepared from a variety of metal precursors, such as platinum ethanolamine, platinum(II)-nitrate, platinum sulfite and tetrammine platinum(II)-nitrate showed similar activities (glycerol conversion 45%) and also identical selectivity (85%) towards hydrogen. The application of different pre-treatment conditions resulted in catalysts with metal particle sizes in a range of 1.6-3.2 nm. In the catalytic reaction selectivity to hydrogen increased with increasing particle size from 78% to 95% while the conversion of glycerol remained nearly constant at 20%. Also, variation of support material from pure gamma-alumina to a mixture of gamma-, delta- and theta-phases (Puralox (R)) led to an increase in hydrogen production from 1.2 x 10(-3) to 7.6 x 10(-3) mol min(-1) g(cat)(-1). The use of crude glycerol as starting material was successful. However, due to impurities (e.g. NaCl) the rate of hydrogen production (7.6 x 10(-3) mol min(-1) g(-1)) was lower than observed for pure glycerol (r(max) = 3.3 x 10(-3) mol min(-1) g(-1)) and decreased dramatically (1 x 10(-3) mol min(-1) g(-1)) after about 4 h time on stream. (C) 2008 Elsevier B.V. All rights reserved.