Preparation and characterizations of Ni-alumina, Ni-ceria and Ni-alumina/ceria catalysts and their performance in biomass pyrolysis

Abstract

The catalytic activity of Ni/Al2O3, Ni/CeO2, and Ni/Al2O3-CeO2 catalysts of different compositions were investigated over biomass pyrolysis process. Catalysts were prepared using co-precipitation method with various compositions of nickel and support materials. Surface characterizations of the materials were evaluated using XRD, SEM, and BET surface area analysis with N2 adsorption isotherm. XRD analysis reveals the presence of Al2O3, CeO2, NiO, and NiAl2O4 phases in the catalysts. Paper samples used for daily writing purposes were chosen as biomass source in pyrolysis. TGA experiment was performed on biomass with and without presence of catalysts, which resulted in the decrease of initial degradation temperature of paper biomass with the influence of catalysts. In a fixed-bed reactor, untreated and catalyst mixed biomasses were pyrolyzed up to 800 °C, with a residence time of 15 min. The non-condensable gases were collected through gas bags every after 100 °C and also at 5, 10, and 15 min residence time at 800 °C, which were analyzed using TCD-GC equipment. Comparative distributions of solid, liquid and gaseous components were made. Results indicated diminished amount of tar production in presence of catalysts. 30 wt% Ni/CeO2 catalyst yielded least amount of tar product. The least amount of CO was produced over the same catalyst. According to gas analysis result, 30 wt% Ni doped alumina sample produced maximum amount of H2 production with 43.5 vol% at 800 °C (15 min residence time).