Effect of Temperature on the Catalytic Performance of Dolomite for H2 Production by Steam Reforming of a Bio-oil/ethanol Mixture

The catalytic performance of dolomite for the steam reforming of a raw bio-oil/bio-ethanol mixture (80/20 mass ratio) was studied in the 400-700 degrees C range. Blank runs (without dolomite) under the same operating conditions were also performed in order to differentiate the catalytic performance of dolomite from the thermal effect. Below 500 degrees C, dolomite mainly promotes inter-conversion reactions between the bio-oil oxygenates, contributing to a noticeable increase in the amount of ketones and phenols, whereas the ethanol conversion is low, once dolomite is saturated with CO2, and a H-2 yield below 10 % is obtained. Above 600 degrees C, dolomite is active for reforming reactions of ethanol and bio-oil oxygenates, and almost steady values of ethanol conversion (100 %), bio-oil conversion (-83 %) and H2 yield (-45 %) are obtained at 700 degrees C throughout 4 h. Cracking reactions of oxygenates are enhanced with the increase in temperature, which involves the formation of gaseous by-products (mainly CH4, with lower amounts of CO and hydrocarbons). The CO2 capture at 600 degrees C shifts the WGS and reforming reactions, providing high ethanol and bio-oil conversion (100 % and 90 %, respectively) and H2 yield (40 %) at zero time on stream, but these reaction indices rapidly decrease when dolomite is saturated.