Optimising metal oxide frameworks
Materials with novel structures and properties form the basis of exciting new applications. Metal oxide frameworks first produced nearly 20 years ago are among those materials. They have very strong chemical bonds that impart rigidity. Simultaneously, they are incredibly empty inside creating not only an ideal storage space for gases but tremendous surface area for chemical reactions. The EU-funded project 'MOFs as catalysts and adsorbents: discovery and engineering of materials for industrial applications' (MACADEMIA) targeted increased efficiency and less environmental impact compared to conventional processes. The focus was on gas separation and storage, liquid separation and catalysis. Hundreds of samples were prepared and novel high throughput screening technology developed to assess performance. Gas separation and storage focused largely on energy-related applications and hydrocarbons. The team investigated propane/propene mixture separation, nitrogen recovery from light hydrocarbons and the separation of benzene from hydrocarbons. Numerous promising materials were identified. Liquid phase absorption and separation focused on xylene separation for production of polyester and other plastics and nitrogen/sulphur adsorption to lower sulphur levels in fuels. MACADEMIA also investigated catalysts for Lewis acid catalysis, an important type of metal-catalysed reaction where background reactions and lack of specificity are the main problem. Metal oxide frameworks with regular periodicity of active sites can act as single-site catalysts for high selectivity and yield with decreased energy. Several materials were developed and tested, demonstrating higher catalytic activity than conventional ones due to regular organisation of the active centres in the framework. Scientists also developed process simulation and predictive models to support development of materials and pilot line setup. Outcomes led to several patents and 97 peer-reviewed publications in high-impact scientific journals. Sorption-based processes for gas and liquid separation and catalysis can significantly contribute to the greening of conventional industrial methods. The commercial potential of metal oxide frameworks for plastics production, fuel purification, carbon dioxide capture and catalysis is quite promising and MACADEMIA has pointed the way to future paths of development.
Keywords
Storage, chemical reactions, metal oxide frameworks, gas separation, liquid separation, catalysis, propane, nitrogen, benzene, xylene, Lewis acid
