Hydrogenation of CO 2 to methanol is an achievable way for “methanol economy” and “liquid sunshine” visions. Owing to highly tunable properties containing different morphologies, exposed crystal facets and oxygen vacancies , In 2 O 3 has become a promising material for CO 2 hydrogenation. Here we successfully introduced highly dispersed Pt 2+ species into three different morphologies In 2 O 3 supports by controllable precipitation method. The dominant exposed crystal facets of In 2 O 3 supports during the research are discovered to greatly affect the dispersion of active Pt 2+ species and the number of oxygen vacancies, as analyzed by diverse characterization techniques, and closely correlated with the catalytic performance. Compared with Pt/In 2 O 3 whcih mainly exposing (222) or (104) facet, Pt/In 2 O 3 which primarily exposed (211) facet obtained higher catalytic activity, including a CO 2 conversion of 11.7% and methanol selectivity of 74.8% with a space time yield of methanol of 0.63 g MeOH h −1 gcat −1 at 300 °C, 5 MPa, and 21,000 cm 3 h −1 g −1 . The highly enhanced activity of 1.5Pt/C-In 2 O 3 -S catalyst was ascribed to its more abundant oxygen vacancies and well-dispersed Pt 2+ species, which derived from the interaction between Pt 2+ and the underlying In 2 O 3 (211) facet. The special interface structure enabled the activation of CO 2 and hydrogenation of key intermediates effectively. Exposing the highly active crystal face of the In 2 O 3 supports is proved to be an effective strategy to enhance catalytic performance of Pt/In 2 O 3 catalyst for methanol synthesis .
Kaihang Sun,Ning Rui,Zhitao Zhang,Zeyu Sun,Qingfeng Ge,Chang-Jun Liu
Supported Pt catalysts have been extensively investigated for CO2 hydrogenation with methane and CO as the principal products. In this work, a Pt/In2O3 catalyst prepared with decomposition precipitation was tested for CO2 hydrogenation to methanol. The Pt/In2O3 catalyst exhibited a highly improved activity towards CO2 hydrogenation, with methanol selectivity of ca. 100% at temperatures below 225 °C, 74% at 275 °C and 54% at 300 °C, respectively, compared to the pure In2O3 catalyst. This represents the highest methanol selectivity reported on Pt catalysts for CO2 hydrogenation. The stability of the Pt/In2O3 catalyst at elevated temperatures has also been higher than that of the pure In2O3 catalyst, indicated by the methanol formation rate decreasing only to 95% of the initial rate after 5 h in the reaction stream and remaining largely constant thereafter. In contrast, the pure In2O3 catalyst loses 20% of the initial methanol formation rate after 9 h in the reaction stream. The characterization of the catalysts confirms that the Pt nanoparticles are well dispersed on In2O3 with a particle size below 3 nm. The strong metal–support interaction (SMSI) between Pt and In2O3 improves the stability of the catalyst and prevents the over-reduction of In2O3. The synergy between the supported Pt nanoparticles and In2O3 balances the hydrogen activation and the density of the surface oxygen vacancies in In2O3, resulting in the high activity for CO2 hydrogenation and enhanced stability of the Pt/In2O3 catalyst.
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