超声波辅助制备微生物柴油的研究

Ultrasonic Wave-assisted Preparation of Microbial Biodiesel

研究了在低频超声波（28kHz和40kHz）的辅助作用下，微生物油脂与短链醇在碱催化作用下进行酯交换反应。研究结果表明，与传统的机械搅拌相比，采用低频超声波，醇油摩尔比为6：1，会使反应时间大大缩短10-40min，同时催化剂的用量也会减少2—3倍。直链醇反应相当迅速，而仲醇和叔醇在60min后基本没有反应。采用28kHz的低频超声波达到了很高的转化率（98％-99％），但反应时间稍长一些；采用40kHz的低频超声波可有效地缩短反应时间10—20min；而高频超声波对脂肪酸的酯交换反应没有强化作用。

The transesterification of microorganism grease with short-chain alcohols, in the presence of basecatalyst, by means of low frequency ultrasound （28 and 40 kHz） in order to obtain biodiesel fuel was studied. By using ultrasounds the reaction time is much shorter （10 -40 min） than for mechanical stirring. The quantity of required catalyst is 2 or 3 times lower. The molar ratio of alcohol/oil used is only 6 ： 1. Normal chain alcohols react fast, while secondary and tertiary alcohols show some or no conversion after 60 min of reaction. Surprisingly, 40 kHz ultrasounds are much more effective in the reduction of the reaction time （ 10 - 20 min ）. Twenty eight kilohertz give slighdy better yields （98% -99% ）, but longer reaction time, while higher frequencies are not useful at all for the transesterification of fatty acids.