Better catalysts benefit clean fuel production
Catalysts play a pivotal role in process intensification by accelerating and steering chemical reactions to the desired products. One emerging strategy is the integration of two catalysts within a single reactor, resulting in consecutive ‘tandem’ reactions. The EU-funded project 3DMULTICAT (3D microscopy-guided assembly of novel hierarchical, multi-pore, multi-function catalysts for clean fuel production) developed innovative solid catalysts for single-step production of liquid fuels from synthesis gas. This gas mixture comprises carbon monoxide (CO) and hydrogen (H2), which can be obtained from natural gas or biomass feedstocks. Project partners sought to develop a new generation of catalysts, with porous structures designed to control the traffic of molecules within their pores. They possess multiple catalytic functions, effecting several reactions in a cascade fashion. The process is based on the integration of two catalytic reactions in a single reactor, namely the Fischer-Tropsch (FT) synthesis of hydrocarbons and the ‘in situ’ hydroprocessing (isomerization and cracking) of the primary products on a hydrocracking catalyst. Through fundamental catalytic studies using model reactants researchers found that unlike under standard hydrocracking conditions, the presence of synthesis gas poisoned the hydrocracking catalyst by strongly absorbing CO, causing the reaction pathway of different FT hydrocarbons on the hydrocracking catalyst to change notably. Encouraged by these findings researchers pursued innovative FT solid catalyst designs aided by 3-dimensional structural quantification methods at the nano- to micrometre scale. Results showed that under relevant reaction conditions, pore mass transport phenomena can affect the primary FT product pattern. Research into cobalt-based FT catalysts led to the development of solid catalysts with complex and hierarchically organized porosities and uniformly distributed catalytic metal species. These proved efficient in controlling molecular traffic and adjusting the nature of the primary FT for tandem catalytic processes. 3DMULTICAT outcomes will help to improve the design of complex porous materials in the field of catalysis and support the sustainable exploitation of natural resources. These advances contribute to environment preservation and climate change mitigation.
