Catalytic steam reforming of biomass-derived tar for hydrogen production with K2CO3/NiO/γ-Al2O3 catalyst

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 aluminasupported Ni catalyst on catalytic performance in steam reforming of biomass-derived tar. Rice husk and K2CO3 were employed as the biomass feedstock and the alkali, respectively. The catalysts were prepared by a wet impregnation method with gamma-Al2O3 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 K2CO3/NiO/gamma-Al2O3 is more efficient for steam reforming of tar released from rice husk than NiO/gamma-Al2O3 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 K2CO3-promoted NiO/gamma-Al2O3 was found to have superior stability due to lower catalyst deactivation.