Bianca Peres Pinto

Green Acetylation of Solketal and Glycerol Formal by Heterogeneous Acid Catalysts to Form a Biodiesel Fuel Additive

A glut of glycerol has formed from the increased production of biodiesel, with the potential to integrate the supply chain by using glycerol additives to improve biodiesel properties. Acetylated acetals show interesting cold flow and viscosity effects. Herein, a solventless heterogeneously catalyzed process for the acetylation of both solketal and glycerol formal to new products is demonstrated. The process is optimized by studying the effect of acetylating reagent (acetic acid and acetic anhydride), reagent molar ratios, and a variety of commercial solid acid catalysts (Amberlyst-15, zeolite Beta, K-10 Montmorillonite, and niobium phosphate) on the conversion and selectivities. High conversions (72-95%) and selectivities (86-99%) to the desired products results from using acetic anhydride as the acetylation reagent and a 1:1 molar ratio with all catalysts. Overall, there is a complex interplay between the solid catalyst, reagent ratio, and acetylating agent on the conversion, selectivities, and byproducts formed. The variations are discussed and explained in terms of reactivity, thermodynamics, and reaction mechanisms. An alternative and efficient approach to the formation of 100% triacetin involves the ring-opening, acid-catalyzed acetylation from solketal or glycerol formal with excesses of acetic anhydride.

Developments in glycerol byproduct-based biorefineries

Abstract: Biodiesel is presently one of the most important biofuels used worldwide. Glycerol or glycerin is a byproduct of biodiesel production, with still few economical applications and can be used as a raw material for the fuel sector. Biotechnological pathways may be used for the production of ethanol, used as biofuel or in the biodiesel transesterification process. Production of syngas from glycerol opens the possibility of obtaining hydrocarbons in the diesel and gasoline range. Many glycerol derivatives can be used as additives for gasoline, diesel and biodiesel, showing the great versatility of this substance.

Transformações Catalíticas do Glicerol para Inovação na Indústria Química

Glicerol ou glicerina e um coproduto da producao do biodiesel e pode ser usado como materia-prima para a industria quimica. A disponibilidade de grandes quantidades de glicerol e a forca motriz para o desenvolvimento de novos processos e produtos baseados em fontes renovaveis de materia-prima. Este artigo discute a transformacao quimica do glicerol em acetais, eteres e esteres do glicerol, com grandes aplicacoes tecnologicas, especialmente como aditivos para combustiveis. A hidrogenolise do glicerol a propeno e desidratacao a acroleina e acido acrilico sao, tambem, discutidas. Por fim, a producao de carbonato de glicerina e evidenciada como forma de agregar a utilizacao de CO 2 e biomassa renovavel.

Glycerol Conversion in the Biorefinery Context

This last chapter discusses the opportunities and challenges of converting glycerol into different chemicals, within the biorefinery context. As most of the biodiesel plants in the world are of low to medium capacity, the surplus of glycerol is somewhat spread and available in small quantities in some regions. Therefore, logistic problems, related to the transportation, storage and purification of the glycerol must be taken into account to choose the best opportunity of investment. Specialty and fine chemicals can overcome these problems, because of the high-added value of the final products. Glycerol derivatives that are used as fuel additives may be the best choice for biodiesel producers, as they can be used in the biofuel to improve its properties. In addition, the process conditions and installations are similar to those used in the manufacture of the biodiesel itself. Finally, the use of glycerol as raw material for the production of commodities may be more suitable to traditional chemical companies. They are usually integrated companies, producing the monomers and the polymers to be used in the automotive, textile, painting and other large sectors. In addition, these companies are used to work with processes in continuous flow at high temperatures and pressures.

Thermochemical Routes of Glycerol Transformation to Commodity Chemicals

The chemical industry ultimately produces polymers for the use of the general public. Today, most of the chemicals are based on oil, coal or natural gas, which reserves are limited and exploitation associated with global warming. In the past years, there were many developments of technological routes to produce chemicals from renewable. The possibility of replacing oil and gas by biomass puts the chemical industry at the forefront of the research and development of new processes. This chapter highlights recent advances in the conversion of glycerol to commodity chemicals, mostly used to produce polymers. Glycerol can be an interesting raw material to replace propylene-based chemicals, such as propylene glycol, acrolein and acrylic acid. Other developments are also discussed, such as a pioneer process of selective glycerol hydrogenolysis to propene itself, as well as production of syngas, hydrogen and methanol.

Thermochemical Routes of Glycerol Transformation in Specialty Chemicals

Glycerol can be converted in ethers, acetals/ketals, esters and carbonate that find applications as fuel additives, special solvents and antioxidant, among others. The reaction of glycerol with ketone and aldehydes leads to the formation of cyclic oxygenated compounds, such as solketal, which is used as a solvent and plasticizer in the polymer industry or as suspension agent in pharmaceutical preparations. It can also be used as a fuel additive. Glycerol ethers comprehend compounds obtained in the reaction of glycerol with alkenes, such as isobutene, or alcohols, such as ethanol. Ether derivatives of glycerol are compatible with diesel and biodiesel fuels, being additives for these fuels. Glycerol dimer and trimer are used as starting materials for the production of emulsifiers in food and cosmetics. The glycerol acetates, monoacetin, diacetin and triacetin have many industrial applications, such as in cryogenics, synthesis of biodegradable polyesters and cosmetics. Glycerol carbonate is a relatively new product that is gaining new applications. Finally, oxidation of glycerol affords different products of high-added value.

Biotechnological Routes of Glycerol Transformation in Valuable Chemicals

Biotechnological transformations of glycerol from the biodiesel industry are highlighted in this chapter. Several strategies based on the biochemical transformation have been studied to convert the residual glycerol into products of higher-added value, such as 1,3-propanediol, 3-hydroxypropanal, ethanol, 2,3-butanediol, lactic acid, succinic acid, citric acid, dihydroxyacetone and hydrogen. The biotechnological conversion of glycerol is an interesting alternative, because the processes are usually highly selective to the desired product and operated near ambient temperature and pressure. This chapter emphasizes the advantages and disadvantages of the biotechnological transformation of glycerol, as well as the factors that still need to be improved for a proper industrial application.

Biomass and Biofuels

Biofuels are the new frontier for vehicular motion. They may be used in blends with traditional fuels, like gasoline and diesel, or neat in some circumstances. Bioethanol and biodiesel are, presently, the most commonly used biofuels in the world. They are primarily produced from edible biomass sources, but new generation of biofuel technologies will provide access to these biofuels from nonedible biomass sources. The chapter discusses the main generations of biofuel production, with particular emphasis in the technologies and raw materials of biodiesel production, as well as the glycerol produced as by-product. A general view of the world market and production of biodiesel, together with the characteristics of the glycerol obtained, is presented, as well as other sources of glycerol production, such as from sugar fermentation, algae and fossil raw materials.