动物油在不同催化剂上的转化

在固定床微反装置内,对动物油在USY,HZSM-5,ANA,Al2O3和SiO2催化剂上的反应行为进行了研究.结果表明,脂肪酸酯分子一般先发生脱羧和脱羰反应(主要是C-O键的断裂),初始裂化反应产生的大分子烃类及其含氧衍生物会在催化剂的酸性位上发生二次裂化和脱氧等反应.USY和HZSM-5分子筛的酸性强,有利于二次裂化,生成较多的液化气和汽油;在具有弱酸位、大孔的Al2O3催化剂上,发生温和的二次裂化反应,转化率略低;而在非酸性的大孔SiO2催化剂及无孔的ANA分子筛上,二次裂化反应被显著抑制,转化率更低,产物中存在大量的含氧衍生物.热裂化反应会产生较多的CO2,而催化裂化反应会产生相对较多的CO.

Conversion of Animal Fat over Various Catalysts

USY, HZSM-5, ANA, Al2O3, and SiO2 catalysts were used to study the effects of catalysts on the conversion of animal fat and yields of products in a fixed-bed microreactor. The results showed that the initial decomposition (mainly cleavage of the C - O bond) of animal fat proceeded through decarboxylation and decarbonylation reactions. Subsequent cracking of the resulting heavy hydrocarbons and oxygenated hydrocarbons into light molecules (such as liquefied petroleum gas and gasoline) occurred on acid sites of the catalysts. The conversion of this secondary cracking over USY and HZSM-5 zeolites was high because of their strong acid sites. However, the weak acidic Al2O3 catalyst containing large pores permitted a mild secondary cracking with a lower conversion. On the other hand, the secondary cracking was strongly inhibited on non-acidic and large pore SiO2 catalyst and non-acidic and none pore ANA zeolite. The conversion on these two catalysts was much low, and there were a lot of heavy oxygenated hydrocarbons in the liquid products. Additionally, more CO2 was produced by thermal cracking, but a relatively more CO was formed by catalytic cracking.