Mechanism-Guided Catalyst Design for CO₂ Hydrogenation to Formate and Methanol

Abstract

Metrics & MoreArticle Recommendations CONSPECTUS: CO 2 to formate/formic acid and methanol has emerged as a promising method for utilizing CO 2 in chemical and fuel synthesis, as well as reducing CO 2 emissions when H 2 is produced through renewable energy sources. This reaction requires the activation of two chemically distinct molecules, CO 2 and H 2 , along with the selective formation of the desired product.Creating efficient catalysts that surpass the limitations of existing catalysts remains a significant challenge. Historically, the development of catalysts has largely depended on trial and error until successful outcomes are achieved. However, recent advances in material synthesis for well-defined structures, reaction kinetics analysis, in situ characterization techniques, and computational studies have facilitated a systematic understanding of catalytic reactions and enabled mechanism-guided catalyst development. This innovative approach has empowered researchers to strategically design effective catalysts that optimize the target reaction, particularly the rate-determining step, while tackling other limitations, such as selectivity and stability. This Account provides an overview of our recent efforts in catalyst development for CO 2 hydrogenation through mechanism-guided engineering, which are primarily divided into two sections: (i) formic acid/formate and (ii) methanol production. For the CO 2 hydrogenation to formate/formic acid, we first discuss the structure−activity correlation studies of various metal/support catalyst systems, including different metal particle sizes, types of support, and crystalline morphologies of the support. These studies highlight the crucial role of electron-rich metal sites for H 2 splitting and an adequate number of weak basic sites for CO 2 activation, which inform the design of improved catalysts with unique architectures. Notably, encapsulated metal cluster catalysts enhance the utilization of metal species and optimize the synergistic interaction between metal active sites and the support material. The encapsulation strategy can also be applied to inexpensive metal elements such as Ni, facilitating the development of highly efficient catalysts. Our primary focus for CO 2 -to-methanol catalysts is the design of active and durable oxide-based catalysts. We first identify that the critical limitation of metal oxide catalysts is their poor H 2 activation capability, based on a comprehensive review of classical and state-of-the-art understanding of the CO 2 -to-methanol catalysts. Consequently, the principal catalyst design concept involves coupling metal promoters, which provide high H 2 activation functionality, with metal oxide catalysts that enable the adsorption of CO 2 and selective methanol synthesis. An essential synthetic approach is the doping of metal promoters on the surface of oxide catalysts. Specifically, atomically dispersed metal promoters significantly improve methanol yield by maximizing interfacial synergy with the oxide catalyst. A remarkable strateg...

Enhanced Methanol Formation over Cu/MgO Catalysts Derived from Mg-Rich Active Hydroxycarbonate Precursors

“…These findings align closely with the existing literature over similar CO 2 reduction catalysts suggesting the critical impact of both BET surface area and the concentration of basic sites in refining methanol selectivity. , Furthermore, high experimental H 2 consumption values over the theoretical showed enhanced reduction of MgO in CM-HT with subsequent increase in strong basic sites (γ) . The CO 2 molecules adsorbed on both sites (i.e., β and γ) undergo sequential hydrogenation steps, ultimately yielding HCOO, H 2 COO, H 2 COOH, and H 2 CO with atomic hydrogen (H) being transferred via H spillover from Cu.…”

“…52,54 Furthermore, high experimental H 2 consumption values over the theoretical showed enhanced reduction of MgO in CM-HT with subsequent increase in strong basic sites (γ). 61 The CO 2 molecules adsorbed on both sites (i.e., β and γ) undergo sequential hydrogenation steps, ultimately yielding HCOO, H 2 COO, H 2 COOH, and H 2 CO with atomic hydrogen (H) being transferred via H spillover from Cu. Moreover, the adsorption of the C�O bond of H 2 CO on the most robust basic sites (γ) causes a reaction with surface hydrogen, resulting in methanol formation.…”

Recent advances in CO2 reduction with renewable reductants under hydrothermal conditions: towards efficient and net carbon benefit CO2 conversion

“…Still far from practical implementation, CO 2 conversion approaches face formidable challenges in terms of renewable reductive sources, easy handling reaction systems, and readily accessible high efficiency. Specifically, (1) catalytic CO 2 hydrogenation exhibits the highest reaction efficiency, while the need for gaseous hydrogen compromises the net carbon benefit since industrial hydrogen production relies heavily on fossil fuels as the feedstock; moreover, the storage and transportation of high pressure gas also require large amounts of energy input; 137 (2) solar or electro induced CO 2 reduction could entirely or partly use solar energy as the energy input which promises the high prospect of achieving net carbon benefit; however, the efficiency of solar reactions is relatively poor now, and the competitive reaction of hydrogen evolution in electrochemical CO 2 reduction interferes with reaction selectivity; and (3) for solar-/electro-CO 2 reduction, delicate prepared catalysts or electrodes are inevitable, leading to difficulties in implementing the technology practically. Therefore, from the perspective of practical applications, it is urgent to develop efficient strategies to use renewable reductants and operable and scalable methods in CO 2 conversion to achieve the dual goals of efficient and net carbon benefit CO 2 reduction.…”

Rational Control of Oxygen Vacancy Density in In2O3 to Boost Methanol Synthesis from CO2 Hydrogenation

“…Based on the theoretical and experimental results, the exact structure–function relationship between the O v density and methanol synthesis performance was clarified. The In 2 O 3 -5 catalyst that was prepared by sequentially carbonizing at 500 °C and oxidizing at 500 °C exhibited excellent methanol yield (9.0 mmol MeOH h –1 g cat –1 ), which is superior to most of pure In 2 O 3 catalytic components that were prepared by the direct calcination step. ,− Our catalyst design concept can be combined with other strategies, such as noble metal doping, ,,,− crystal structure engineering, , electronic structure modulating, − etc. to further boost the methanol synthesis performance of the In-based catalyst via CO 2 hydrogenation technology.…”