Efficient catalytic conversion of small molecules for synthetic fuels and chemicals

Title : Efficient catalytic conversion of small molecules for synthetic fuels and chemicals

Abstract:

Efficient utilization of green hydrogen has become the focal point for achieving the net zero target. Hydrogenation has consistently posed a significant challenge in many domains, including renewable energy, bulk chemical production, and petrochemical engineering. The specific technical difficulties mainly include targeted bond cleavage, efficient oxygen removal, enhancing low-temperature activity, and the optimization of catalyst stability. We employed various probe reactions of carbon molecules to elucidate our comprehension and strategies concerning controllable hydrogenation and catalyst stability promotion.

In the context of enhancing catalytic activity, we showcased Mo₂C-carbon with nonstoichiometric metal defects dramatically improved the selective hydrogenation efficiency for the Reverse Water-Gas-Shift (RWGS) reaction of CO₂ (CO₂+H₂=CO+H₂O) at low-temperatures, surpassing noble metals and other Mo based catalysts. For the RWGS reaction, Mo₂C supported on modified graphene (Mo₂C@NGn) demonstrated outstanding catalytic performance at temperatures as low as 300°C with good stability, surpassing many noble metal catalysts. Modeling reveals defects were essential for balancing the negative charge of H atoms, facilitating their surface migration and accelerating products desorption with reduced magnetization of the active site^1,2. In terms of curbing excessive hydrogenation of C₂H₂ (C₂H₂+H₂=C₂H₄), we harnessed the oxygen vacancies within the Pd-SrTiO₃ (STO) system to induce Pd-Ti alloy formation. With the Pd-STO solid-solution induced by O vacancy, the C₂H₄ desorption became an exothermic process, facilitating the semi-hydrogenation of acetylene, and greatly benefiting the highly selective production of C₂H₄³. As for optimizing catalyst stability, we overcame the stability challenge inherent in nickel-based catalysts in dry reforming reactions (CH₄+CO₂=2CO+2H₂) with two distinct strategies for achieving long-term catalyst stability. The deactivation regions of the Ni-based catalyst were discovered to display distinct colors during the CH₄-CO₂ dry reforming. Operando TEM revealed the deactivation mechanism in both oxidizing and reducing atmospheres. From the perspective of in-situ regeneration and surface modification, we proposed a gas-switching strategy that effectively ensured catalyst long-term stability, which could also be attained by another steady-state strategy of oxidation state regulation.

The research we are sharing encompasses comprehensive results, obtained from operando experiments and multi-scale modeling. Our study elaborates on several strategies for regulating the local electronic structure of catalytic active centers, which include defect engineering, dynamic coordination, alloy modification, and elemental doping. By realizing these strategies, we have successfully achieved precise hydrogenation of different carbon molecules and a remarkable promotion of the catalyst life.

Audience Take Away: 

• The advancement of controllable hydrogenation in hydrocarbon resource utilization.

• The state-of-the-art fundamental knowledge on local electron regulation, enabling highly efficient catalysis

• The practicable strategy to deal with the deactivation of catalysts with detailed mechanisms elaboration

Biography:

Professor Luo is a Fellow of the Royal Academy of Engineering and a Member of Academia Europaea. He has a PhD from Cambridge University and has been a full professor of the University of London since 2002. He has held various positions at Imperial College London; Queen Mary, University of London; Southampton University; Tsinghua University; and University College London. He is specialized in modelling and simulation across scales, with application in energy, power and interdisciplinary fields. He founded and has led the “UK Consortium On Mesoscale Engineering Sciences” since 2013 to advance mesoscopic, atomistic and multiscale modelling and simulation.