The Study Of High Acid Value Oil’s Esterification Reaction In Pipeline Reactor

As the traditional fossil energy reserves is dwindling, more attention and advocating is paid to the new alternative energy. Biodiesel, as a kind of fossil diesel fuel substitute, with its good performance and friendly environment effect, got wide attention by many countries all-over the world. Recently, the main bottleneck that restricting the development of biodiesel in our country is the cost of raw material. Using high acid value oil to produce biodiesel, which with lower cost of the raw material, more extensive sources, and it must be the new direction for the future of biodiesel manufacturing. Pipeline reactor as a kind of continuous reactor, has the incomparable advantage that compare to the batch reactor. It can save energy consumption, increase production capacity in the industrialized mass production, it is also convenient to control. This paper is about high acid value oil’s esterification reaction in pipeline reactor.It aims to provide a basis for the application of biodiesel preparation that using high acid value oil. The research content is as follows:(1) Through two-step solution, saponification and acid decompose to prepared Jatropha oil fatty acids, measured the acid value is191.91mgKOH·g-1, the density under20℃is C.857g·mL-1. Then different ratio of acid ester grease formula is deduced. According to the formula, using Jatropha oil and Jatropha oil fatty acid as raw materials, to prepare five different acid value oil, these acid value respectively are:190mgKOH·g-1,150mgKOH·g-1,110mgKOH·g-1,70mgKOH·g-1,30mgKOH·g-1. Set up a pipeline reactor, the reactor filled with4A molecular sieve as dehydrating agent, by adjusting the material flow velocity to control the reaction time, through thermostatic water bath to provide the heating environment. With Jatropha oil fatty acids as raw material to explore the optimum process conditions of this pipeline reactor: using methanol soak molecular sieve for3h, debugging the thermostatic water bath as the temperature of60℃, and the8h’s molecular sieve continuous working time, In addition, by comparing the catalytic performance of p-toluenesulfonic acid and concentrated sulfuric acid, determined use the concentrated sulfuric acid as the better catalyst for this study.(2) Carried out an esterification reaction experiment with5different acid value oil in the Pipeline Reactor. Experimental results show that when the acid value of oil is190mgKOH·g-1, the oil-methanol ratio is8:1, the dosage of catalyst is4%for the oil, acid value within60min can be decreased to37.40mgKOH·g-1, and the conversion rate can be80.32%; When the acid value of oil is150mgKOH·g-1the oil-methanol ratio is9:1, the dosage of catalyst is4%for the oil, acid value within120min can be decreased to13.83mgKOH·g-1, and the conversion rate can be90.78%; When the acid value of oil is110mgKOH·g-1, the oil-methanol ratio is8:1, the dosage of catalyst is4%for the oil, acid value within60min can be decreased to8.10mgKOH·g-1, and the conversion rate can be92.64%; When the acid value of oil is70mgKOH·g-1, the oil-methanol ratio is9:1, the dosage of catalyst is4%for the oil, acid value within60min can be decreased to11.57mgKOH·g-1, and the conversion rate can be83.47%; When the acid value of oil is30mgKOH·g-1, the oil-methanol ratio is9:1, the dosage of catalyst is4%for the oil, acid value within60min can be decreased to5.72mgKOH·g-1, and the conversion rate can be80.93%; Oil with different acid value has different esterification reaction effects in the pipeline reactor. Among them,110mgKOH·g-1oil has the highest conversion rate,150mgKOH·g-1and70mgKOH·g-1oil second,190mgKOH·g-1and30mgKOH·g-1oil has a relatively lowest conversion ratio. Through the analysis of all the test data, based on the optimization scheme of this pipeline reactor:the oil-methanol ratio is8:1, the dosage of catalyst concentrated sulfuric acid is4%, the reaction time of60min (that is, the flow velocity is0.62cm·min-1). The influence degree of various factors to the conversion rate is:acid value> oil-methanol ratio> dosage of catalyst> reaction time (flow velocity).(3) Established the kinetic equation of rsterification reaction which expressed by the initial concentration of fatty acid and the conversion rate, that is:r=k[CA0(1x)]2. Under the condition that the oil-methanol ratio is8:1, the dosage of catalyst is4%, got the5kinds of speed constant of kinetic equation:190mgKOH·g-1with0.240mol·L-1·min-1,150mgKOH·g-1with0.304mol·L-1·min-1,110mgKOH·g-1with0.413mol·L-1·min-1,70mgKOH·g-1with0.652mol·L-1·min-1,30mgKOH·g-1with1.521mol·L-1·in-1. Deduced a design equation of this pipeline reactor which associated by the kinetic equation, the size of pipeline, the flow of materials, the concentration of materials and the conversion rate, that is: According to this equation, made a comparison in predicted value and measured value of the former experiment data, it turned out that the equation has a good fit when the flow of materials are large.