固体碱催化剂上生物油催化酯化改质

采用湿混法制备了以γ-A l2O3为载体的固体碱催化剂(M gCO3/γ-A l2O3,Na2CO3/γ-A l2O3,CaCO3/γ-A l2O3,K2CO3/γ-A l2O3),将K2CO3/γ-A l2O3催化剂用NaOH溶液浸渍得到K2CO3/γ-A l2O3-NaOH催化剂。以乙酸和乙醇的酯化反应为模型反应,对所制备的固体碱催化剂的酯化反应活性进行了评价,并在筛选出的酯化反应活性较高的K2CO3/γ-A l2O3催化剂上,对生物油催化酯化改质进行了研究。实验结果表明,生物油经催化酯化改质后,运动黏度显著降低,流动性增强,稳定性提高;改质后生物油的pH由2.60升到5.35,运动黏度降低了86.2%,热值提高了45.8%;同时,改质后的生物油中酸类物质含量减少、酯类物质含量增加,挥发性和难挥发性的有机羧酸转化为酯。

Upgrading of Bio-Oil by Esterification over Solid Base Catalyst

The solid base catalysts,MgCO_3/γ-Al_2O_3,Na_2CO_3/γ-Al_2O_3,CaCO_3/γ-Al_2O_3 and K_2CO_3/γ-Al_2O_3 were prepared by mixing carbonates with γ-Al_2O_3 as support.The catalysts were used in esterification of bio-oil.K_2CO_3/γ-Al_2O_3-NaOH catalyst used in esterification was prepared by impregnation of K_2CO_3/γ-Al_2O_3 in 1mol/L NaOH solution.Activities of catalysts for esterification were evaluated with acetic acid and ethanol as model reactants at 80℃ in stirring batch reactor.Catalytic activity of K_2CO_3/γ-Al_2O_3 catalyst was the highest.The chosen highly active K_2CO_3/γ-Al_2O_3 was then used in esterfication of bio-oil for upgrading.After reaction kinematic viscosity of bio-oil lowered,its fluidity was improved and its stability was enhanced.Quality upgrading of bio-oil was as expected.The pH of bio-oil rose from 2.60 to 5.35,its kinematic viscosity reduced by 86.2% and its heating value increased by 45.8%.GC-MS analysis showed that esterification of bio-oil was truly enhanced by solid base catalysts,with decrease of acidic substances and increase of esters.