ECOCAT · Improving the economic feasibility of the biorefinery through catalysis engineering: enhancing the catalyst performance and optimizing valuable product yields

Improving the economic feasibility of the biorefinery through catalysis engineering: enhancing the catalyst performance and optimizing valuable product yields

The growing energy demand globally, in combination with environmental concerns and concerns with the dependency on finite fossil energy resources and energy security, has spurred research into alternative energy resources. Lignocellulose is a non-edible, abundant and low-cost form of biomass that can be converted to a liquid renewable energy carrier (bio-oil) via a process known as fast pyrolysis. Bio-oil is a complex mixture of oxygenates derived from biomass and has some unfavourable properties that make its conversion to transportation biofuels very challenging. By incorporating a solid catalyst in the fast pyrolysis process, the biomass-derived products can be partially deoxygenated and a bio-oil with more favourable properties can be produced that can be upgraded to transportation fuels. The disadvantage of using a catalyst is the formation of byproducts such as coke, water and permanent gases. In addition, the need to periodically replace the catalyst has a significant impact on the economics of the process and the cost of the products. The aim of ECOCAT was to improve on the economics of catalytic fast pyrolysis by reducing catalyst-related operating costs. This can be achieved by the development of a more active catalyst with superior selectivity towards key valuable products. The most commonly used catalyst for catalytic fast pyrolysis is the ZSM-5 zeolite, a catalyst with a unique microporous structure that is very effective for the production of valuable monoaromatic hydrocarbons and for the minimisation of solid byproducts (coke). However, the microporous structure of ZSM-5 may not be optimal for the conversion of the large biomass-derived compounds that are formed during. As such, adding a degree of mesoporosity in the ZSM-5 may be beneficial for the cracking of the large compounds into smaller intermediates, which can then diffuse through the micropores to be converted to valuable deoxygenated products. In ECOCAT, ZSM-5 zeolites with varying degrees of added mesoporosity were synthesised. The mesoporous ZSM-5 zeolites were both more active and more selective than microporous ZSM-5 and gave consistently higher yields of desirable products.

Data: CORDIS, © European Union