Study On Production Of Aromatic Hydrocarbons From Bio-oil Light Components

It is of great significance for the utilization of biomass to produce aromatic hydrocarbons from bio-oil catalytic cracking.Water phase obtained by water extraction from bio-oil enriches light components is more suitable for cracking than crude bio-oil.In this paper,an improved process of two-stage hydrogenation-cocracking with methanol was developed,in view of the hydrogen-lacking property of bio-oil causes coking problem easily.Hydrogenation-cocracking performances of bio-oil light components and the actual bio-oil water phase with methanol were studied.Firstly,a typical compound of bio-oil light components,furfural,was selected to study the effects of hydrogenation temperature and the methanol blending ratio of on the preparation of aromatic hydrocarbons.The results showed that,increasing the hydrogenation temperature is beneficial to the saturation of the furan ring,which promoted the formation of aromatic hydrocarbons in the cracking process.But gasification reaction became severe under the overhigh hydrogenation temperature.Increasing the methanol blending ratio is also beneficial to increase the overall aromatic hydrocarbons yield.Hydrogenation temperature of 250 ? and the blending ratio of 25%furfural 75%methanol is more suitable for hydrogenation-cocracking.Under this condition,oil phase products were completely composed of hydrocarbons,and the relative content of aromatic hydrocarbons was up to 94.4%.The hydrogenation-cocracking reaction mechanism was constructed to explain the theory of hydrogen supplying based on the experimental results.Secondly,acids and ketones are important components in the bio-oil.Hydrogenation-cocracking behaviors of the mixture of typical acids and ketones(acetic acid and hydroxy acetone)and methanol were investigated.It was found that interaction between these components existed in the hydrogenation-cocracking process:the presence of ketones promoted the conversion of acids;and the addition of methanol further improved the oil phase yield and quality,and inhibited formation of coke.The oil phase yield of 35.5%was obtained from hydrogenation-cocracking of 30%acetic acid and 30%hydroxy acetone and 40%methanol.Oil products were completely composed of hydrocarbons,and the relative content of aromatic hydrocarbons was up to 95.2%.The reaction mechanism of hydrogenation-cocracking of mixtures of acids and ketones and methanol was summarized.Finally,The actual bio-oil water phase enriches light components like acids,ketones and aldehydes was used for hydrogenation-cocracking with methanol to produce aromatic hydrocarbons.The effects of hydrogenation temperature and the methanol blending ratio on the preparation of aromatic hydrocarbons were investigated.It was found that the hydrogenation temperature of 250 ? and the blending ratio of bio-oil water phase and methanol of 1:1 were more suitable for hydrogenation-cocracking.Under this condition,the yield of oil phase was up to 22.5%,and the relative content of aromatic hydrocarbons was up to 96.6%.In addition,the hydrogenation-cocracking process was found to be more favorable for the generation of aromatic hydrocarbons compared to the direct cocracking process.