Synthesis gas and H2 production by chemical looping reforming using bio-oil from fast pyrolysis of wood as raw material

The interest of using bio-oil produced by biomass fast pyrolysis to generate H2 and high value chemicals is growing up in order to reduce CO2 emissions by the use of biomass. In the present work, bio-oil Chemical Looping Reforming was demonstrated in a 1 kWth continuous unit during 60 h of operation using a Ni-based oxygen carrier to produce syngas/H2. No agglomeration of the oxygen carrier was detected. Complete conversion of the bio-oil was obtained in all cases, obtaining as main products H2, CO, CO2 and in much lower concentration CH4. Carbon deposition in the bed appeared in almost all the experiments carried out during the bio-oil reforming, and CO2 was found in the air reactor outlet, although did not affect to the process performance when oxygen carriers were used. This fact only let to a reduction of the CO2 capture efficiency. Fuel reactor temperature was a key factor for the H2 production, the H2/CO ratio and the carbon accumulated in the CLR unit. The maximum H2 production together with the maximum H2/CO ratio of 6 were found at the lowest temperature used, 650 °C. In addition, the carbon formed in the fuel reactor was reactive enough so that it could be burnt in the air reactor with minimum accumulation in the continuous unit. The autothermal H2 production was 13.6 g/100 g of bio-oil without water at 650 °C with a H2O/bio-oil = 6, which corresponds to 68 mol H2/kg of bio-oil without water. Therefore, the CLR process of bio-oil allows obtaining high H2 production with low carbon deposition at 650 °C using less amount of water than in conventional bio-oil reforming.