Development of a catalytic microreactor for aqueous phase reforming of biofeeds

Hydrogen production by means of Aqueous Phase Reforming (APR) is an excellent way of valorization of waste biomass. In APR, a water soluble carbohydrate and liquid water undergo a reforming reaction at mild conditions (ca. 200 ºC, 25 bar) in the presence of a reforming catalyst like Pt/Al2O3 to produce highly pure H2 and CO2. The low temperatures result in suppression of CO production and reduction of the energy input compared to traditional gas phase reforming. The very low CO content of the gas produced, makes this technology excellently suited for combining it with PEM fuel cells, thereby making this an attractive option for power generation at remote locations. In this work, we are developing a catalytic microreactor system for aqueous phase reforming. H2 is selectively produced by combining catalysis and micro-reactor engineering. APR of sorbitol was conducted in a washcoated microchannel. A well adherent, stable and uniform 5 µm layer of Pt/AlO(OH) was washcoated on the walls of a 320 µm ID microchannel. Due to enhanced mass transfer properties, undesired hydrogenation reactions could be avoided, thus enhancing the H2 formation. The selectivity towards H2 in the microchannel was greatly increased compared to that in a fixed bed reactor (60 vs. 20 % at the same conversion), resulting in an overall increased turnover frequency (461 h-1 vs. 173 h-1). According to these results, the use microtechnology for APR would allow for a great reduction in the reformer size, thus being promising for distributed H2 production.