Steam Reforming Of Bio-oil With Modified Ni/Olivine Catalyst

In the process of biomass gasification for hydrogen production, the presence of bio-oil leads to pipeline blockage, corrosion of equipment damage, and serious environmental pollution problems. Bio-oil is the major obstacles of biomass gasification technology development and industrialization. Of the methods of bio-oil removal, catalytic cracking, by which the tar will be converted into small molecular components in the gasifier, has attracted great interest. Bio-oil steam reforming process can be achieved in the External Circulating Concurrent Moving Bed developed in our group. During the process, bio-oil is conversed in situ, char is recycled continuous and catalyst is regenerated. The catalyst is used as heat carrier providing the energy needed for pyrolysis and gasification. For the process requirements, we developed the modified olivine nickel catalyst (NiO/MO). Also, the steam reforming of bio-oil from pine pyrolysis with NiO/Olivine and NiO/MO catalysts was carried out in a fixed bed reactor.In order to increase the steam reforming activity of NiO/Olivine, the olivine support is modified by molding technique through addition of calcium aluminate cement (CA) as binder followed by calcination. The modified olivine (MO) is prepared through a serious of processes by milling the olivine, mixing the olivine powder with CA, molding, curing, drying and calcination. The NiO/MO catalysts are prepared by wetness impregnation. The catalyst preparation paremeters are:amount of NiO loading 5wt%, calcination temperature 900℃.The results showed that the porosity of MO is above 30%, the BET surface ares increses, and the attrition rate is comparable to the raw olivine. SEM image shows that the pore structure of the NiO/MO catalyst is well-developed. XRD characterization shows that there are new phase of nickel aluminum and nickel-magnesiun spinel material. TPR characterized shows that the reduction temperature of NiO/MO catalyst increased from 600 to 750℃which noted that the interaction between the NiO and carrier has enhanced, improving the stability of the catalyst. The comparative catalytic activity study of the NiO/MO and NiO/olivine showed that, the carbon conversion on the Ni/MO catalyst is over 90%,30% more compared with that of the NiO/Olivine. The (H2+CO) content in product gas increased nearly 20%. The comparative catalytic activity study of the NiO/MO and Z409 showed that the carbon conversion rate of the Ni/MO catalyst is still higher, but the Z409 has a higher hydrogen yield and (H2+CO) selectivity.The regeneration performance of NiO/MO catalysts was investigated. The results showed there is active component loss. TPR analysis showed that the reduction temperature range of the regenerated catalyst has changed, which is due to the change of the interaction between the NiO and the carrier. Carbon conversion rate is maintained up to 70% after eighth regenerations of the NiO/MO catalyst.In order to improve reforming activity of Ni/MO catalyst, the addition of MgO, Fe2O3 and K2O promoter was investigated. It was shown that the addition of MgO improved the interaction between the active component and carrier. NiO-MgO solid solution phase improved the thermal stability of NiO/MO. The addition of Fe2O3 improved the interaction between active component and carrier, the catalyst becomes easier to reduce, and H2 yield increased. The optimized amount for MgO and Fe2O3 addition is 10wt% and 2wt%, respectively. The effect of addition K2O on catalyst performance was investigated. The addition of K has greatly improved the catalytic activity and reforming performance of the catalyst.