碱性季胺聚砜膜制备及其催化酯交换反应的研究

Preparation and catalytic performance of quaternized alkaline polysulfone membrane for transesterification reaction

以聚砜(PSf)为原材料,通过氯烷基化和季胺化后浇铸成膜,进一步进行碱化处理制备碱性聚砜膜.采用红外光谱表征聚砜膜的化学结构,并将此碱性季胺聚砜膜用于催化大豆油酯交换反应制备生物柴油.考察并优化了原料油中含水率、共溶剂种类、共溶剂添加量以及醇油质量比对酯交换反应转化率的影响.研究结果表明,在醇油摩尔比9∶1,碱性聚砜膜用量为油重的2%,反应时间1h,正己烷添加量为油重的50%,反应温度65℃,大豆油转化率达到最大值95.2%.当原料油中的含水率≤5%时,碱性季胺聚砜膜可以吸收原料油中的水分,原料油中的水分对酯交换反应影响较小.碱性季胺聚砜膜重复使用5次后,酯交换反应转化率没有明显下降.

A quaternized alkaline polysulfone （PSf） membrane used for catalysis of transesterification reaction was developed by successive processes of chlorin alkylation,quaternary amination and alkalization of PSf.The grafting of polysulfone was characterized by Infrared Spectroscopy.The quaternized alkalization polysulfone membrane was used to catalyze the transesterification of soybean oil for biodiesel.The effects of water content,the kinds of co-solvents,the amount of co-solvent and the molar ratio of methanol/soybean oil on the conversion of transesterification were studied and optimized.The experimental results showed that the conversion of soybean oil reached the maximum value of 95.2％ under the reaction condition：the molar ratio of methanol/soybean oil of 9 ∶ 1,the amount of alkaline polysulfone membrane of 2wt％ （weight of soybean oil）,the reaction time of 1 h,the amount of n-hexane of 50％ （weight of soybean oil） and the reaction temperature of 65 ℃.When the water content of soybean oil was below 5 ％,the quaternized alkalization polysulfone membrane could absorb the water in soybean oil,and the water had few effects on the transesterification reaction.After the reuse of the quaternized alkalization polysulfone membrane for 5 times,transesterification conversion did not decrease significantly.