Synthesis Of Biodiesel From Soybean Oil Using Solid Acid And Co-Solvent

As supply of fossil fuels is limited whilst energy demand continues to rise, research is increasingly directed towards alternative renewable fuels. Biodiesel, consisting of methyl esters of fatty acids produced by transesterification of vegetable oils with methanol, has attracted considerable recent attention because of its environmental benefits and the fact that it comes from renewable resources. Indeed, biodiesel has already entered the fuel market as a diesel oil substitute. It is superior to diesel oil in terms of sulfur content and aromatic content, as well as safety and biodegradability.Biodiesel is usually prepared through transesterification with the presence of liquid acid or alkaline catalyst. However, many problems occurred when using these methods. If we choose alkaline catalyst, material oil and methanol have to be dried completely in order to avoid emulsification. And free fatty acid will do harm to basic catalyst. Meanwhile there are also several disadvantages when using liquid acid catalyst, such as erosion of reaction vessel, complicated post treatment, cost increasing. Furthermore, no matter liquid acid catalyst or basic catalyst, post treatment process will drain lots of waste water to pollute environment. Therefore solid acid catalyst becomes a focus of attention with its outstanding environment-friendliness.We choose two kinds of solid acid catalysts (Zr(SO4)2-4H2O&SO42-/ZrO2) and one kind of supported solid acid catalyst(Zr(SO4)2/AC) incorporating co-solvent to investigate the process of transesterification. The principle variables, reaction temperature, molar ratio of methanol to oil, reaction time, amount of catalyst, affecting the yield of methyl esters were investigated and the most feasible reaction condition and catalyst were screened out accordingly. After comparison, we found that our biodiesel product has a very similar properties with diesel0#in China.As a result, with Zr(SO4)2·4H2O as catalyst and CO2as co-solvent in the reaction systems, there was a significant decrease in the severity of the conditions required for usual reaction, which makes the production of biodiesel using Zr(SO4)2·4H2O and CO2viable as an industrial process.Furthermore, the solid acid and co-solvent can be recycled after suitable pretreatment and the production process is environmentally friendly.