Ca/Al固体碱催化菜籽油制备生物柴油

采用共沉淀法制备了Ca/Al复合氧化物固体碱催化剂,考察了沉淀剂种类、Ca/Al摩尔比、沉淀温度、溶液pH值、老化时间和焙烧温度等制备条件对其催化剂活性的影响。采用正交实验方法得到制备Ca/Al复合固体碱催化剂前躯体的最佳制备条件为,沉淀剂NaOH,Ca/Al摩尔比为3,沉淀温度为60 ℃,沉淀过程中pH值保持在10,在90 ℃老化18 h。在该最优条件下制备的催化剂前驱体主要以Ca₄Al₂O₆(NO₃)₂·10H₂O晶相存在,在N₂气保护下300 ℃焙烧2 h后,催化剂形成高分散钙铝复合氧化物,且碱性强度达到26.5以上。在催化菜籽油和甲醇的酯交换反应中,菜籽油的转化率达到95%,脂肪酸甲酯的质量分数为95.9%。

Synthesis of biodiesel from rapeseed oil catalyzed by Ca/Al solid base

Ca/Al solid basic catalysts were prepared by co-precipitation method and used in the synthesis of biodiesel from rapeseed oil;the effect of preparation conditions such as precipitant selection,mole ratio of calcium to aluminum,precipitation temperature,pH value,aging temperature and time,and calcination temperature on their catalytic activity were investigated.Through orthogonal tests,the optimal conditions to prepare catalyst precursor are obtained as Ca/Al = 3,NaOH as precipitant,precipitation temperature of 60 ℃,pH value of 10,and aging at 90 ℃ for 18 h.Under the optimal conditions,the catalyst precursor obtained is in the form of Ca4Al2O6(NO3)2·10H2O crystal.After calcination at 300 ℃ for 2 h in N2 atmosphere,Ca/Al mixed oxide is then highly dispersed on the catalyst surface with a pH value of above 26.5.The catalyst exhibits excellent activity in transesterification of rapeseed oil with methanol;the conversion of rapeseed oil and selectivity to fatty acid methyl ester reach 95% and 95.9%,respectively.