Development of Nano-NiO/Al2O3 Catalyst to be Used for Tar Removal in Biomass Gasification

Abstract

The objective of this study isto develop a novel supported nano-NiO catalyst for tar removal in biomass gasification/pyrolysis, to significantly enhance the quality of the produced gases. For this purpose, the supported nano-NiO/gamma-Al2O3 catalyst was prepared by deposition-precipitation (DP) method. Different analytical approaches such as XRD, BET, TEM and SEM/EDX were used to characterize the synthesized catalysts. The results showed thatthe prepared nano-NiO/gamma-Al2O3 catalysts had a coated structure with a loading of NiO in catalysts over 12 wt %, and they had also a higher BET surface area over commercial nickel based catalysts. The active components of catalyst were spherical NiO nanoparticles coated on the surface of supports with a size range of 12-18 nm. Furthermore, the activity of the catalysts to remove tar in the process of biomass pyrolysis was also investigated using a bench-scale combined fixed bed reactor. The experiments demonstrated that the tar yield after addition of the catalyst was reduced significantly; the tar removal efficiency reached to 99% for catalytic pyrolysis at 800 degrees C, and the gas yield after addition of the catalyst increased markedly. The compositions of gas products before and after addition of the catalyst in the process also changed significantly. The percentages of CO2 and CH4 in the product gas after addition of the catalysts were obviously reduced, while those of the valuable H2 and CO strongly increased. Therefore, using the prepared NiO/gamma-Al2O3 catalyst in biomass gasification/pyrolysis can significantly improve the quality of the produced gas and meanwhile efficiently eliminate the tar generation.