Concrete as low-cost catalyst to improve gas quality during biomass gasification in a pilot-scale gasifier

摘要

Concrete was evaluated as low-cost catalyst for in-situ application in an autothermal 80 kWth pilot-scale bubbling fluidized bed direct (air) biomass gasifier. To improve the understanding of the observed phenomena, the process was also evaluated in smaller-scale reactive system, namely an externally heated 3 kWth bench-scale bubbling fluidized bed.Concrete application showed promising results regarding the relative increase of H-2 concentration and H-2/CO molar ratio in the producer gas (up to 99.2 and 77.4%, respectively), indicating that this material can promote the water-gas shift reaction. However, this effect was dependent on the gas-solid contact time and catalyst temperature, being that it was only relevant when these parameters were at least 5.2 s and 746 degrees C, respectively. A maximum lower heating value of 7.5 MJ/Nm(3) of the producer gas was found with concrete application (23.8% relative increase), which is higher than commonly found in the liter-ature. Relative increases of up to 25.1, 55.3 and 47.0% for the specific dry gas production, cold gas effi-ciency and carbon conversion efficiency, respectively, were also found, consequently suggesting that, in addition to the promotion of the water-gas shift reaction, this material has potential to promote tar reforming/cracking and carbon gasification reactions. (C) 2021 Elsevier Ltd. All rights reserved.