焙烧态水铝钙石催化剂的制备及催化合成生物柴油

Preparation of calcined hydrocalumite and its catalytic effect on synthesis of biodiesel

分别采用共沉淀法、清洁法制备焙烧态水铝钙石,通过低温N2吸脱附法、CO2-TPD、XRD、DTA和FT-IR表征结构,并将其作为大豆油与甲醇酯交换合成生物柴油的催化剂,探讨制备方法对焙烧态水铝钙石催化合成生物柴油的影响。此外,考察了Ca/Al摩尔比、焙烧温度、甲醇与大豆油摩尔比(醇油比)、催化剂用量和反应时间对酯交换合成生物柴油的影响。结果表明,清洁法制备的焙烧态水铝钙石具有更高的比表面积,强碱中心的表面碱量更大,催化活性更高。当Ca/Al摩尔比为2∶1,焙烧温度为600℃时,制备的Ca2AlO-2-600催化剂的催化活性最高,在醇油比8∶1、催化剂用量3%、反应温度65℃、反应时间4 h的条件下,大豆油转化率达到98.0%。催化剂经重复使用3次后仍保持较高催化活性。

Calcined hydrocalumite was prepared by precipitation method and cleaning method respectively.The structure of calcined hydrocalumite was characterized by N2 adsorption and desorption at low temperature,CO2-TPD,XRD,DTA and FT-IR.Then the catalytic activities of calcined hydrocalumites prepared by the two methods were evaluated by the transesterification of soybean oil with methanol to synthesize biodiesel.In addition,the effects of Ca/Al molar ratio,calcination temperature,molar ratio of methanol to soybean oil,amount of catalyst and reaction time on the transesterification synthesis of biodiesel were also investigated.The results showed that the calcined hydrocalumite prepared by cleaning method had higher specific surface area,surface alkali content in strong alkali center and catalytic activity.And Ca2AlO-2-600 prepared under the conditions of Ca/Al molar ratio 2∶1,calcination temperature 600℃had the highest catalytic activity with the conversion rate of soybean oil 98.0%under the tranesterification conditions of molar ratio of methanol to soybean oil 8∶1,amount of Ca2AlO-2-6003%,reaction temperature 65℃and reaction time 4 h.The catalyst remained highly catalytic activity after three times of reuse.