Investigation On Catalytic Hydrogenation Of Bio-oil’s Light Components Over Modified Raney-Ni Catalyst

Preparation of bio-oil from biomass with pyrolysis method is simple and high efficient, but its efficient application still need further modification. The purpose of this paper is to reduce the bio-oil’s inorganic acid, the contents of unsaturated compounds such as aldehyde and ketone. In order to achieve higher saturated alcohol content and lower biological oil acid, the methods of neutralization, hydrogenation and esterification hydrogenation can be used, meanwhile raising the stability of bio-oil.First of all, in the high pressure reaction kettle, the influences of temperature, cold-press of hydrogen and the performance of catalyst on the hydrogenation of bio-oil in real system under the catalyst of homemade Raney-Ni were discussed. Experimental results show that the highest yield of saturated alcohols reached 70.67%,which was obtained under the condition of 6.0 MP and 140℃,but acid content slightly reducing from 36.52% to 20.41%. In the process of bio-oil hydrogenation, the esterification reaction between acids and alcohols and dehydration reaction between alcohols also happened.Secondly, high acid content in bio-oil is easy to corrode the reactor and influence the effect of catalyst. Acids in bio-oil can be reduced by pretreatment methods of neutralization with Na2CO3 or CaCO3 respectively. The results show that the acids of bio-oil is greatly decreased as the process of neutralization and catalytic hydrogenation, acids changed from 42.19% to 6.86%, then reduced to zero, and saturated alcohol selectivity increasing to 90.02%. However, the carbonate neutralization bio-oil exist a certain amount of coke after catalytic hydrogenation, liquid products have poor stability and metal ions lead to increasing bio-oil ash content.Moreover, in view of the bio-oil’s pretreatment process of carbonate neutralization, organic matter content such as phenolic and macromolecular acid reduce in bio-oil, which due to the large insoluble or molecules with precipitation reaction. The bio-oil pretreated by supercritical methanol esterification for reducing acid, then use catalytic hydrogenation. The results showed that the suitable alcohol/oil is 2:1. At the same time, with Mo modified Raney Ni show better effect of hydrogenation the Sn modified Raney Ni.Finally, using the method of immersion on Raney Ni prepare metal modified Raney Ni, respectively. This paper use modified Raney Ni as catalysts in catalytic esterification-hydrogenation one step method on bio-oil model compounds for qualitative research. We study the effect of metal modified catalyst in the reaction. The experimental results show that the Fe-RN can curb the alcohol’s alkylation action, and Mo-RN have obvious hydrogenation effect. In the one step reaction of esterification-hydrogenation, phenol’s conversion rate up to 76.94% and product selectivity of cyclohexane and cyclohexane were 92.31%,7.69% respectively.