CO₂ Hydrogenation to Methanol over a Pt-Loaded Molybdenum Suboxide Nanosheet with Abundant Surface Oxygen Vacancies

Abstract

Hydrogenation of carbon dioxide (CO 2 ) using CO 2 -free hydrogen (H 2 ) to produce methanol (CH 3 OH) is a promising reaction that can alleviate both carbon emissions and the dependence on fossil fuels. Nonstoichiometric molybdenum suboxide coupled with Pt nanoparticles (NPs) acts as a promising catalyst for this reaction, in which surface oxygen vacancies (V O ) and the redox ability of Mo in molybdenum suboxide are the keys to transforming CO 2 into the CO intermediate and further to afford CH 3 OH. In this study, a series of molybdenum oxides with different morphologies, including bulk, nanosheet, nanobelt, and rod morphologies, are used as catalysts, and the effects of particle morphologies on the catalytic performance toward CO 2 hydrogenation are examined. A Pt-loaded molybdenum suboxide nanosheet (Pt/ H x MoO 3−y (Sheet)) with a high specific surface area affords 1.35 times greater CO 2 conversion and CH 3 OH yield in liquid-phase CO 2 hydrogenation compared with the corresponding bulk analog under relatively mild reaction conditions (total 4.0 MPa, 200 °C). Experiments and comprehensive analyses, including X-ray diffraction and in situ X-ray absorption fine structure studies, reveal that the enhanced activity of Pt/H x MoO 3−y (Sheet) is attributable to a high concentration of surface-exposed V O sites, which are introduced in the (010) plane during the H 2 reduction due to the high surface-to-volume ratio of the nanosheet-structured MoO 3 . In addition, the nanosheet-structured catalyst exhibits better reusability because of its antiaggregation behavior for Pt NPs compared with the conventional bulk analog.

Sodium Promoted FeZn@SiO2-C Catalysts for Sustainable Production of Low Olefins by CO2 Hydrogenation

“…Combined with our previous work [29,30], GC-modified mesoporous silica-encapsulated metal nanoparticles can effectively improve reducibility and electron conductivity properties similar to those of expensive noble metals (Pt [31] and Ru [32]). In this study, FeZnNa@SiO 2 -C catalysts were prepared by the sol-gel method via regulating the amount of Na loading.…”

Review of Mechanism Investigations and Catalyst Developments for CO2 Hydrogenation to Alcohols

“…This indicated that CO 2 hydrogenation follows the formate pathway. Kuwahara et al [67] found that a Pt-loaded molybdenum suboxide nanosheet structure showed a high CO 2 conversion and methanol yield, which was about 1.35 times higher than that of other molybdenum suboxide supports (including bulk, nanostrip and rod) under similar volume. This is because the high specific surface area of the Pt-loaded molybdenum suboxide nanosheet structure could form more oxygen vacancies for CO 2 adsorption and activation and inhibit Pt aggregation.…”