Inspirational perspectives and principles on the use of catalysts to create sustainability

Producción CientíficaMost of the products on which our welfare state is based are composed of chemicals. The growth of the world's population, its ageing and the continuous improvement of welfare state aspirations augur an increase in the needs for all these everyday products in our lives. A high percentage of these chemicals are synthesised using catalysis. In this perspective paper, we highlight the importance of catalysis, which is at the heart of chemical processes, and therefore one of the tools for creating products that drive sustainability. We have compiled twelve methodological best practices in catalyst design and conception that can serve as inspiration for the creation and improvement of catalysts. We include some application examples to illustrate this.Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (project PID2019-105975GB-I00

Recovery of carbon fibres and production of high quality fuel gas from the chemical recycling of carbon fibre reinforced plastic wastes

A solvolysis process to depolymerize the resin fraction of carbon fibre reinforced plastic waste to recover carbon fibre, followed by hydrothermal gasification of the liquid residual product to produce fuel gas was investigated using batch reactors. The depolymerisation reactions were carried out in ethylene glycol and ethylene glycol/water mixtures at near-critical conditions of the two solvents. With ethylene glycol alone the highest resin removal of 92.1% was achieved at 400 °C. The addition of water to ethylene glycol led to higher resin removals compared to ethylene glycol alone. With an ethylene glycol/water ratio of 5, at 400 °C, resin removal was 97.6%, whereas it was 95.2% when this ratio was 3, at the same temperature. The mechanical properties of the recovered carbon fibre were tested and showed minimal difference in strength compared to the virgin carbon fibre. The product liquid, containing organic resin degradation products was then subjected to catalytic supercritical water gasification at 500 °C and 24 MPa in the presence of NaOH and Ru/AlO as catalysts, respectively. Up to 60 mol.% of H gas was produced with NaOH as catalyst, and 53.7 mol.% CH gas was produced in the presence of Ru/AlO

Technology readiness level assessment of composites recycling technologies

Composite materials made of glass and carbon fibres have revolutionised many industries. Demand for composites is experiencing rapid growth and global demand is expected to double. As demand for composites grows it is clear that waste management will become an important issue for businesses. Technically composite materials evoke difficult recycling challenges due to the heterogeneity of their composition. As current waste management practices in composites are dominated by landfilling, governments and businesses themselves foresee that this will need to change in the future. The recycling of composites will play a vital role in the future especially for the aerospace, automotive, construction and marine sectors. These industries will require different recycling options for their products based on compliance with current legislation, the business model as well as cost effectiveness. In order to be able to evaluate waste management strategies for composites, a review of recycling technologies has been conducted based on technology readiness levels and waste management hierarchy. This paper analyses 56 research projects to identify growing trends in composite recycling technologies with pyrolysis, solvolysis and mechanical grinding as the most prominent technologies. These recycling technologies attained high scores on the waste management hierarchy (either recycling or reuse applications) suggesting potential development as future viable alternatives to composite landfilling. The research concluded that recycling as a waste management strategy is most popular exploration area. It was found mechanical grinding to be most mature for glass fibre applications while pyrolysis has been most mature in the context of carbon fibre. The paper also highlights the need to understand the use of reclaimed material as important assessment element of recycling efforts. This paper contributes to the widening and systematising knowledge on maturity and understanding composites recycling technologies

Crosslink Density Changes during the Hydrolysis of Tridimensional Polyesters

The hydrolysis of almost ideal networks based on macrodiols of average molar mass about 2 kg mol 1, with L¼18 ester groups per chain is studied. Tensile testing is used to evaluate the crosslink density through the statistical theory of rubber elasticity at two temperatures and three values of relative humidity. A kinetic model for ester consumption including an autocatalysis term is proposed and combined with two original approaches for modeling the crosslink density changes. This allows kinetic parameters of hydrolysis to be determined, and very good predictions are obtained for the variations of crosslink density (or elastic modulus) in the three aging conditions considered. The initial curvature of elastic modulus versus time is predicted positive for weak autocatalysis and negative for strong autocatalysis. The obtained conversion ratio at degelation is found to decrease sharply with the number of esters per elastically active chaincontrat de recherche SAFRAN - ART