Sistemas (bio) catalíticos verdes para el desarrollo de procesos químicos sostenibles de interés industrial

Résumé

The design of new sustainable chemical processes, based on the development of efficient catalytic syntheses with the appropriate combination of new reaction / separation protocols, are fundamental elements for the development of the chemical industry in the immediate future, since they entail significant savings in the production cost, as well as minimizing environmental impacts. Therefore, it is of utmost importance to replace volatile organic solvents with non-volatile and fully recoverable solvents (i.e. ionic liquids, scCO2, DES, etc.), as well as the use of high-efficiency heterogeneous (bio)catalysts, which allow their reuse, providing high selectivities and minimal generation of by-products. Thus, it is possible to avoid additional product purification steps, as well as to improve and facilitate the integration of the transformation and separation steps. Green Chemistry is a scientific philosophy that focuses on the design of processes and chemical reactions that reduce or minimize the generation of products that are harmful to humans and the environment as a whole. From the chemical sector point of view, the fundamental idea is to minimize or eradicate the use of dangerous substances and transform those that can already be generated into non-toxic compounds. It is clearly a goal that can not be easily achieved. In this sense, chemical processes include steps in which substances are progressively transformed to obtain the desired product. However, the process requires the use of traditional organic solvents that can be aggressive with the environment and secondary compounds are also generated, becoming highly toxic. Generally, solvents are used as auxiliary materials in chemical synthesis, since they act as a reaction medium and improve the transport and separation of the product. However, the vast majority of solvents used in laboratories are molecular liquids, which belong to the group of volatile organic compounds, and their recovery can never be total, and their reuse is usually associated with distillation processes that require a lot of Energy. For this main reason, their replacement and / or elimination is not an easy task, since due to their functionality they turn out to be key elements in most chemical processes. In recent years, with the main objective of creating a more environmentally friendly chemical industry, focusing on the use of alternative reaction media and more sustainable synthetic strategies. These alternative solvents (that is, ionic liquids or Supercritical fluids), offer the possibility of being recovered and reused in their entirety, which is why their exploitation as an alternative to organic solvents is today at the forefront. This Doctoral Thesis has been developed in the conceptual field of Sustainable Chemistry, with direct contributions of applications of interest to various industrial sectors. In this way, this Doctoral Thesis successfully presents the development and design of chemical processes that integrate the synthesis and separation of products of great industrial interest with high added value in the pharmaceutical and food sectors and cosmetics, as well as in the polymer industry. The protocol approaches developed offer the synergistic advantages provided by different sustainable elements, such as ILs, DES, scCO2 and enzymes, and their appropriate combination, to obtain the products in an efficient and safe way. In addition, protocols for the separation of products have been implemented, with easy extrapolation for possible scaling at an industrial level, in various synthetic products such as fragrances, omega-3 fatty acid monoacylglycerides, or cyclic carbonates. Additionally, it has also been possible to demonstrate the adequacy of all solvent-free reaction systems, even based on solid substrate mixtures at room temperature, for the verification of biotransformations through the formation of DESs, or the assistance with ultrasounds, obtaining products of interest for the cosmetic industry (e.g. panthenol monoesters, xylitol monoesters).