Maria Aparecida F. César-Oliveira

Applications of Heterogeneous Catalysts in the Production of Biodiesel by Esterification and Transesterification

Abstract The development of solids with suitable catalytic properties has been one of the main drivers for the development of sustainable heterogeneous catalytic processes for the conversion of renewable resources in different forms of liquid biofuels such as biodiesel, bio-oils and synthetic hydrocarbons. The search for such catalytic processes is also listed as one of the main drivers for the development of green chemistry. However, heterogeneous solid catalysts are usually more expensive and less effective than homogeneous catalytic systems but they may offer other advantages such as selectivity, recyclability, low toxicity, easily handling and processing as well as a lower environmental impact due to the reduction of process wastes and effluents. This chapter describes a series of heterogeneous catalytic processes that are currently available for biodiesel production. Structural details of these catalysts are described along with their catalytic performance in both esterification and transesterification reactions.

Síntese de copolímeros metacrílicos através da modificação química do poli(metacrilato de metila) de massa molar Controlada

Controlled molecular weight poly(methyl methacrylate) (PMMA) was synthesized in toluene solution using benzoyl peroxide/dodecanethiol as initiator/chain transfer agent system. The effect of the thiol concentration on the molecular weight of PMMA was investigated. Methyl methacrylate and methacrylic acid copolymers, P(MMA-MAA), were prepared by partial hydrolysis of the PMMA homopolymers of different molecular weights. By reacting the acid residues of the copolymers with long chain alcohols, in the presence of 1,3-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, copolymeric esters of PMMA with long chain substituents, such as hexadecyl, were obtained. This technique has not been reported in the literature for the synthesis of PMMA esters.

Biodiesel: Matérias-Primas, Tecnologias de Produção e Propriedades Combustíveis

The entire biodiesel production chain developed tremendously in regions all over the world and this biofuel has established itself as one of the main alternatives to replace petroleum-derived fuels. Several studies have already demonstrated its compatibility with diesel oil and the international standards have evolved to ensure safety and satisfaction to the end-users. Although already losing priority in stronger economies such as United States, Germany and France, this production chain is still expanding considerably in emerging economies such as Brazil, where it has been established as a project of great scientific, technological, political and economic interests. In this article, important aspects of the biodiesel production and use are revised in detail, particularly in relation to the availability of suitable raw materials in large scale as well as to the chemistry involved in the technologies available to date for its conversion to biofuels that are fully compatible with diesel fuel applications.