Experimental study on wood chips gasification over Ni/dolomite

The catalytic activity of Ni/dolomite during biomass (wood chips) gasification was examined in a fluidized bed reactor. Ni-dolomite with Ni contents of 0% (dolomite), 10%, 20% and 25% (25%Ni/dolomite) was prepared by precipitating method. Effect of equivalence ratio, ER (0.078–0.128), temperature (700–850 °C) and Ni content on syngas composition, gas yield (GY), tar content in the product gas (TC), char conversion efficiency (CCE) and cold gas efficiency (CGE) was studied. An increase in ER led to an increase in GY and CCE, while TC gradually decreased. Increasing temperature contributed to more char conversion, gas production and tar elimination. The results also showed that Ni/dolomite had a high catalytic activity in terms of tar cracking/reforming, upgrading the produced syngas quality, as well as enhancing char conversion. Higher Ni content (0–20%) was more favorable for gas production, char conversion and tar reduction. However, a further increase in Ni content led to a slight increase in the gas quality and yield due to coke formation and subsequently a reduction in the availability of CaO and MgO active sites. Comparing with dolomite, the use of Ni/dolomite improved the gas quality and the gasifier performance, the optimal value of Ni content was found to be 20% at 850 °C and ER of 0.128.