Supercritical water reforming of glycerol: Performance of Ru and Ni catalysts on Al2O3 support

Supercritical water reforming of glycerol was studied in a tubular fixed-bed reactor using a Ru/Al2O3 catalyst, and was compared with our previous study using a Ni-based catalyst, with the aim of enhancing the performance of a global process designed under energy self-sufficient conditions. Relatively high glycerol concentrations of up to 25 wt.% and temperatures from 500 to 800 °C were tested. Glycerol conversion was very high (>99%) at temperatures of 600 °C and above, but low at 500 and 550 °C (<50%) using the Ru/Al2O3 catalyst. The gas product (dry basis) was mainly CH4 and CO2, while H2 production was quite low, against expectations. Under the same operating conditions, the behavior of the catalysts is quite different as the Ni catalyst promotes H2 production much more than the Ru catalyst. A detailed discussion is provided on our results and those of previous studies using the Ru/Al2O3 catalyst, thus acquiring more insight into the catalyst behavior. The Ru catalyst showed a large increase in its crystalline phase after testing, although the oxidation state of ruthenium did not change.