Supercritical transesterification route for biodiesel production: Effect of parameters on yield and future perspectives

Abstract

Catalyst‐free biodiesel production through supercritical transesterification is faster with the high conversion and a more environment‐friendly route than conventional catalyst transesterification. Improving and exploring the new possibilities in this alternative biodiesel production method by including newly available technology will lead us to a more sustainable future. In this paper, supercritical transesterification of biodiesel production has been reviewed in detail. The different parameters of this method, such as temperature, pressure, molar ratio, alcohol types, and residence time which affect the yielding and quality of fuel, have been reviewed. Besides, recycling the energy and suitable feedstock for this method has also been explored to reduce the intensive energy demand and operating cost. Furthermore, light has also thrown on co‐solvents effect on this method to reduce the extreme reaction conditions required. At last, the review concludes future recommendations in supercritical transesterification along with the challenges in energy integration and recycling.

New Catalysts for Biodiesel Production under Supercritical Conditions of Alcohols: A Comprehensive Review

“…Despite SCF advantages over other traditional methods, the process faces many obstacles due to harsh reaction conditions, high‐energy consumption (high temperature and pressure requirements), and high molar ratio of alcohol to triglycerides, as well as being expensive and producing higher amounts of glycerol. A large number of studies have focused on reducing high SCF parameters to obtain higher biodiesel using co‐solvents and catalysts, and for increasing heat recovery by applying an energy integration process (e. g. heat exchangers) [6a,63h,65] . Aboelazayem et al [66] .…”

Current State and Perspectives on Transesterification of Triglycerides for Biodiesel Production

“…The transesterification reaction between supercritical alcohol and triglycerides occurs in the absence of any catalysts. Once the alcohol molecules reach the supercritical region, hydrogen bonding in the alcohol dramatically decreases, allowing alcohol molecules to behave similar to an acid catalyst [226][227][228]. At particularly high pressure and temperature, for instance, 240 • C and 78.60 bar, methanol behaves similarly to a supercritical fluid, and the nature is similar to a compressible fluid with an intermediate density between a liquid and a gaseous fluid that allows excellent mass transfer characteristics due to the low surface tension and viscosity.…”

A Short Review on Catalyst, Feedstock, Modernised Process, Current State and Challenges on Biodiesel Production

“…To overcome the increased demand of edible oil in food industries with high cost of feedstock [38], the selection and studies of the potentials different of non-edible oil feedstock for low costly biodiesel production is highly required. Non-edible feedstock that are currently utilized for the effective low-cost biodiesel production are Jatropha curcas oil, waste cooking oil, grease oil, and palm fatty acid distillate (PFAD) [39]. Many palm oil factories produced waste from crude palm oil refining in Malaysia, which reaches up to 17.4 million metric tons generated from the palm oil industries [40].…”