Microreactor technology for biodiesel production: a review

Due to a rise in global demand for energy and an increase in greenhouse gases, biodiesel has been accepted as an alternative fuel because of its biodegradability, low environment detrimental effect, better quality of exhaust gas emission, and renewability. Biodiesel is a mixture of monoalkyl esters of long-chain fatty acids also known as fatty acid methyl esters. Transesterification is the most commonly adopted technique for the production process. But the conventional biodiesel technology has its own disadvantages. Process intensification technologies can overcome these drawbacks. Some novel reactors such as microchannel reactor, static mixers, oscillatory flow reactors, and spinning tube reactors have been developed so as to improve mass transfer and mixing. These technologies can achieve rapid and high reaction rates due to the high surface area/volume ratio and short diffusion distance thus intensifying the transesterification process. Various factors such as alcohol to triglyceride molar ratio, microchannel size, residence time, reaction temperature, mixing mechanism, and catalyst affect the production process. Although biodiesel production has been commercialized in several countries, it still requires a clean, effective, and environment-friendly technology to make it cost-effective and increase its competency against conventional fossil fuels. Microreactor technology, however, has proved to be a benchmark to serve this purpose. The current review paper provides an overview about different types of microreactors used in biodiesel production and the parameters affecting biodiesel production in microreactors. The microreactor technology discussed in this paper aims to improve the production process by decreasing the reaction time from hours to minutes.