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

Abstract

Nowadays, due to detrimental carbon dioxide emissions and dwindling non‐renewable fossil energy from crude oil, biodiesel from green sources such as vegetable oils, animal fats, waste oils and microbial oils have been described as a promising non‐fossil fuel, renewable, sustainable, clean, and biodegradable. So far, transesterification is the most superior process for converting green resources into biodiesel by reacting with alcohol in the presence of a catalyst. This process is influenced by some considerations such as alcohol to oil molar ratio, reaction temperature, reaction pressure, reaction time and specifically the amount of catalyst, which greatly affect the reaction performance and the biodiesel production. In depth, this review will discuss novel catalysts for biodiesel production under supercritical methanol and ethanol conditions by reviewing published articles related to this field to date.

Investigation of Jatropha Oil Transesterification into Methyl Esters under Supercritical Methanol Environment using Advanced Heterogeneous Catalysts

“…Finally, the cationic group in the alkoxide anion interacts with the diglyceride anion, resulting in the formation of diglyceride. The complete reaction occurs by repeating these steps twice on the carbon chain of the fatty acid [2c] . In the following, experiments were conducted with different parameters to accurately achieve the best possible results.…”

Optimization and kinetic study of biodiesel production from Jatropha curcas oil in supercritical methanol environment using ZnO/γ-Al2O3 catalyst

“…Thus, different alternative catalysts are developed in order to eliminate the disadvantages caused by these catalysts [5,6]. The abovementioned drawbacks give priority to the application of heterogeneous catalysts due to their reusability, non-corrosive properties, ease of separation, lower cost, energy savings, enhanced fatty acid alkyl ester yield, and biodiesel purity, as well as its high tolerance to water and FFAs in the feedstocks [7]. According to Ramos et al [8], drawbacks of heterogeneous catalysis in transesterification reactions encompass lower conversion rates that may necessitate more rigorous reaction conditions compared to homogeneous catalysis, as well as mass transfer resistance resulting from the presence of three phases (oil, alcohol, and catalyst) in the reaction mixture.…”

“…This will be elaborated upon in the following. The authors strongly recommend stopping on the review that synthesizes the results of multiple investigations focused on developing heterogeneous catalysts utilizing a diverse range of waste, natural, or commercial materials under supercritical conditions of alcohols [7]. These types of studies serve as a valuable resource for comprehending the current state of the field and identifying promising avenues for further exploration.…”