Solid acid catalysts for biorefinery processes

The present work regards the study of alternative synthetic routes for biofuels and biochemicals. Biofuels and biochemicals constitute the two main classes of biorefinery products. Biofuels are obtained from biomass and have many environmental advantages over the traditional fuels. In this work particular attention has been given to biodiesel, one of the most widely used biofuels. Biodiesel is a safe, non-toxic, and biodegradable alternative diesel fuel. The development of active acid catalysts for biodiesel synthesis could reduce the production costs, in particular because the acid catalysts permit the use of low value feedstocks such as waste and non-edible oils. Biodiesel production occurs with co-production of glycerol, which is co-product also in other industrial productions such as the production of fatty acids and soaps. Because of its large production the market demand is largely less than the supply. For this reason glycerol is considered a problematic product. Possible solution to its disposal is the use as platform chemical in the production of high value bioproducts. Among them are particularly interesting the trioses dihydroxyacetone and glyceraldehyde. They could be feedstocks for an alternative synthetic way for lactic acid and its esters. Lactic acid and lactates are, nowadays, considerably important because they are used as building blocks in the production of biodegradable polymers (the polylactic acids), which are potential substitute for petroleum derived polymers. Lactic acid is also one of the most promising bio-based platform molecules. The high costs of the conventional production process hinder the use of lactic acid and lactates in many applications. So it is essential to develop cheaper and greener synthetic routes. In this work catalysts synthesis, characterization of the materials, and catalytic testing have been carried out mainly at the Laboratory of Industrial Chemistry in the Department of Chemical and Geological Sciences of the University of Cagliari. The study involved the use of several techniques for the characterization of the materials. All the catalytic results have been related to the acid properties of the tested materials. For this reason the measurements of adsorption microcalorimetry and adsorption FTIR using basic probe molecules have been the most important used techniques in this work. The measurements of adsorption microcalorimetry were carried out at the Laboratory of Industrial Chemistry in Cagliari while the measurements of adsorption FTIR were carried out under the supervision of Prof. Konstantin Hadjiivanov at the Institute of General and Inorganic Chemistry of the Bulgarian Academy of Sciences. This work is divided in five chapters. The first chapter is an introduction of the fundamentals of sustainable chemistry, biorefinery and acid-base heterogeneous catalysis. The second chapter is a description of the most important techniques for the characterization of acid-base properties of solid materials. In the third chapter are listed the used materials, the experimental procedures and apparatus. The chapter four is the study of the acid catalyzed transesterification of tryglicerides for the production of biodiesel and glycerol. In chapter five is described the work on the conversion of dihydroxyacetone to methyl lactate