Heterogeneous catalysis is widely applied in industry due to important advantages it offers to chemical processes such as improved selectivity and easy catalyst separation from reaction mixture, reducing process stages and wastes. This is the reason why nowadays heterogeneous catalysts are being developed to produce biodiesel. Several catalytic materials have been showed in bibliography: acid solids capable to carry out free fatty acids esterification reaction, base solids which are able to carry out triglycerides transesterification reaction and bifunctional solids (acid–base character) which show ability to simultaneously catalyze esterification and transesterification reaction. This review discusses the latest advances in research and development related with heterogeneous catalysts used to produce biodiesel.

Recent developments on heterogeneous catalysts for biodiesel production by oil esterification and transesterification reactions: A review

Biodiesel production using heterogeneous catalysts.

Steep hikes of petroleum prices and rising demand of petroleum products compels the scientific society to think for the renewable alternative fuels like biodiesel. Biodiesel production is generally carried out through the process of transesterification reaction. The reaction is facilitated with a suitable catalyst either homogeneous or heterogeneous. The selection of appropriate catalyst depends on the amount of free fatty acids in the oil. Heterogeneous catalyst provides high activity, high selectivity, high water tolerance properties and these properties depend on the amount and strengths of active acid or basic sites. Basic catalyst can be subdivided based on the type of metal oxides and their derivatives. Similarly, acidic catalyst can be subdivided depending upon their active acidic sites. New varieties of mixed catalyst are also available in literatures. Catalyst generated from bio-waste and other biocatalysts which are heterogeneous in nature and extensively reported in literature are also reviewed. This review focused about the recent invention and use of the heterogeneous acid, base and biocatalysts for biodiesel production and their suitability for industrial application.

Modern heterogeneous catalysts for biodiesel production: A comprehensive review

MFI zeolite nanosheets tailored to 2.5-nm thickness were synthesized using a surfactant-type zeolite structure-directing agent, [C22H45–N+(CH3)2–C6H12–N+(CH3)2–C6H13](Br–)2. The zeolite nanosheets possessed Bronsted acid sites on their external surfaces as well as in the internal micropore walls. The acid strength and concentration was characterized by the 31P NMR signals of the adsorbed trimethylphosphine oxide and tributylphosphine oxide. The 31P NMR investigation identified three types of Bronsted acid sites with different strengths on external surfaces; there were four types inside the micropores. A linear correlation has been established between the number of the external strongest acid sites and the catalytic activity in decalin cracking for the MFI zeolite catalysts investigated in this work.

Characterization of the Surface Acidity of MFI Zeolite Nanosheets by 31P NMR of Adsorbed Phosphine Oxides and Catalytic Cracking of Decalin

Biodiesel has provided an eco-friendly solution to fuel crisis, as it is renewable, biodegradable and a non-toxic fuel that can be easily produced through enzymatic transesterification of vegetable oils and animal fats. Enzymatic production of biodiesel has many advantages over the conventional methods as high yields can be obtained at low reaction temperatures with easy recovery of glycerol. Microbial lipases are powerful biocatalysts for industrial applications including biodiesel production at lower costs due to its potential in hydrolyzing waste industrial materials. Among them, lipases from yeasts, Candida antarctica, Candida rugosa, Cryptococcus sp., Trichosporon asahii and Yarrowia lipolytica are known to catalyze such reactions. Moreover, stepwise addition of methanol in a three step, two step and single step reactions have been developed using yeast lipases to minimize the inhibitory effects of methanol. The latest trend in biodiesel production is the use of whole-cell as biocatalysts, since the process requires no downstream processing of the enzyme. Synthesis of value added products from the byproduct glycerol further reduces the production cost of biodiesel. This review aims at compiling the information on various yeast lipase catalyzed transesterification reactions for greener production of biodiesel.

Enzymatic transesterification for production of biodiesel using yeast lipases: An overview

http://cmdmc.com.br/redecmdmc/lab/arquivos_publicacoes/2931_Production%20of%20biodiesel%20by%20esterification%20of%20palmitic%20acid%20over%20mesoporous.pdf

Alipio C. Carmo

Papers

Production of biodiesel by esterification of palmitic acid over mesoporous aluminosilicate Al-MCM-41