Catalytic steam reforming of biomass-derived tar for hydrogen production with K_2CO_3/NiO/γ-Al_2O_3 catalyst

摘要

A major problem of using Ni-based catalysts is deactivation during catalytic cracking and reforming, lowering catalytic performance of the catalysts. Modification of catalyst with alkali-loading was expected to help reduce coke formation, which is a cause of the deactivation. This paper investigated the effects of alkali-loading to alumina-supported Ni catalyst on catalytic performance in steam reforming of biomass-derived tar. Rice husk and K_2CO_3 were employed as the biomass feedstock and the alkali, respectively. The catalysts were prepared by a wet impregnation method with γ-Al_2O_3 as a support. A drop-tube fixed bed reactor was used to produce tar from biomass in a pyrolysis zone incorporated with a steam reforming zone. The result indicated that K_2CO_3/NiO/γ-Al_2O_3 is more efficient for steam reforming of tar released from rice husk than NiO/γ-Al_2O_3 in terms of carbon conversion and particularly hydrogen production. Effects of reaction temperature and steam concentration were examined. The optimum temperature was found to be approximately 1,073 K. An increase in steam concentration contributed to more tar reduction. In addition, the K_2CO_3-promoted NiO/γ-Al_2O_3 was found to have superior stability due to lower catalyst deactivation.