Different kind of catalyst used in biomass gasification using different kind of reactors has been published in the literature. Corella et al. (2008a, b) used small pine wood chips as biomass in fluidized bed gasifier along with steam reformer reactor and two shift reactors for hydrogen production. They have reported 73 vol.% of hydrogen with 140 g/kg of biomass yield using Ni-based commercial catalyst. Furthermore, they stated that 90 % CO conversion to H2 via water gas shift reaction due to using of catalyst in the shift reactors. Along with the high production rate they have stated that not only the system is very complex with fluidized bed, steam reformer, and two shift reactors but also the hydrogen production cost is very high. Along with this they stated that the overall process is technically feasible, meaning that there are no technical major problems.

Li et al. (2009) studied the palm oil waste (mixture of EFB + fiber + shell) for hydrogen production. They used fixed bed reactor with pure steam as gasification agent and tri-metallic catalyst, i. e., NiLaFe/y-Al2O3. They have investigated the effect of steam/biomass ratio, temperature, and particle size on the hydrogen pro­duction. They reported 59 vol.% hydrogen with yield of 133.25 g/kg of biomass at 1,173 K and steam/biomass ratio of 1.33. Their results showed that hydrogen is increased by increasing temperature. For steam/biomass ratio, initially hydrogen increased by increasing steam/biomass ratio, but at high steam/biomass ratio hydro­gen decreased. This is due to the decrease of temperature at high steam/biomass ratio in fixed bed reactor. Furthermore, the smaller biomass particles produced more hydrogen compared to the bigger particle size. They have reported that the catalyst has a strong impact on the hydrogen yield in steam gasification of biomass. Hydrogen yield without catalyst was reported 39.75 g/kg of biomass and by using catalyst hydrogen yield increased till 101.78 g/kg of biomass under the same condi­tions. Furthermore, the type of catalyst also plays important role for hydrogen pro­duction in biomass steam gasification.

He et al. (2009) studied the catalytic steam gasification of municipal solid waste in bench scale fixed bed gasifier using calcined dolomite as catalyst. They reported that the catalyst not only increased the hydrogen yield but also completed decom­posed tar in the system in the presence of steam at high temperature. The highest hydrogen concentration was obtained 53.29 mol% with the yield of 84 g/kg of bio­mass. Furthermore, they reported that the system has potation to produce 140 g/kg of biomass hydrogen yield at high temperature. The use of catalyst has proved that there is remarkable increase in the hydrogen yield and concentration and decrease of CO and CH4 due to the water gas shift reaction and steam reforming of the hydro­carbons. They did not detect any tar during the catalytic steam gasification.

Xiao et al. (2010) utilized large amount of animal waste (livestock manure com­post) as biomass. They investigated the effect of temperature, steam, and catalyst using fluidized bed gasifier and Ni-Al2O3 as catalyst. They reported that the both temperature and steam are in favor of hydrogen concentration and yield in catalytic steam gasification, as the methane reforming and water gas shift reaction moves to the product side. Furthermore, catalyst simultaneously promotes tar cracking and steam reforming reactions.