固体酸改质生物油的研究

Study on upgrading of bio-oil catalyzed over solid acids

利用乙酸和乙醇生成乙酸乙酯的酯化反应为模型反应,筛选得到催化活性最好的固体酸催化剂40%S iO2/TiO2-SO42-。在一定的反应条件下,添加固体酸催化剂和溶剂,生物油的品质得到提高,热值提高了50.7%,运动黏度降低到原来的10%,密度降低了22.6%。生物油改质前后的GC-MS分析表明,固体酸可以将生物油中含有的有机羧酸转化为酯类,如甲酸酯、乙酸酯等,使生物油中的羧酸组分发生了催化酯化反应,改善了生物油的品质,生物油物理化学性能得到明显的提高。3A分子筛对生物油的脱水作用不显著,对酸性、密度、黏度等方面影响较小。

Bio-oil production from fast pyrolysis of biomass has aroused great attentions and interests extensively in recent years because the excess consumption of fossil fuels and high efficiency of biomass pyrolysis technique. The product of fast pyrolysis of biomass, bio-oil, has deleterious properties of high viscosity, thermal instability, corrosiveness and chemical complexity, which results in many obstacles to their applications. A novel upgrading process, selective esterification over solid acid catalysts, were suggested. With model compounds of acetic acid and ethanol reacted to get ethyl acetate, solid acid catalysts 40% SiO/TiO2-SO4^2- was selected as the best one for esterification activity. Upgrading of bio-oil over this solid acid catalyst in the subsequent experiment was investigated. The heating value increases by 50.7%. Dynamic viscosity is only one tenth of that of the original. Density of bio-oil is lowered by 22.6%. GC-MS analysis shows that organic acids are converted to esters such as formate, acetate et al over the solid acid by undergoing catalytic esterification. All of those proved that the properties of bio-oil are improved. However, the dehydration characteristic of 3A molecular sieve is not good and it has little effect on the properties of acidity, density and viscosity.