State of the art and perspectives in heterogeneous catalysis of CO2 hydrogenation to methanol.

The ever-increasing amount of anthropogenic carbon dioxide (CO2) emissions has resulted in great environmental impacts. The selective hydrogenation of CO2 to methanol, the first target in the liquid sunshine vision, not only effectively mitigates the CO2 emissions, but also produces value-added chemicals and fuels. This critical review provides a comprehensive view of the significant advances in heterogeneous catalysis for methanol synthesis through direct hydrogenation of CO2. The challenges in thermodynamics are addressed first. Then the progress in conventional Cu-based catalysts is discussed in detail, with an emphasis on the structural, chemical, and electronic promotions of supports and promoters, the preparation methods and precursors of Cu-based catalysts, as well as the proposed models for active sites. We also provide an overview of the progress in noble metal-based catalysts, bimetallic catalysts including alloys and intermetallic compounds, as well as hybrid oxides and other novel catalytic systems. The developments in mechanistic aspects, reaction conditions and optimization, as well as reactor designs and innovations are also included. The advances in industrial applications for methanol synthesis are further highlighted. Finally, a summary and outlook are provided.

Enhanced catalytic peroxymonosulfate activation over carbon shells encapsulating cobalt ferrite via radical and nonradical routes.

Well-defined carbon shells encapsulating CoFe2O4 deliver superior performance in catalytic PMS activation for organics degradation with a reaction rate constant of 0.269 min-1, 4.7 times the hollow CoFe2O4 and 2.7 times the solid carbon sphere encapsulated one. This is attributed to the comprehensive effects of the Co2+ and C[double bond, length as m-dash]O active sites for free radical and nonradical mechanisms. The nanostructured materials outperformed most of the carbon- or cobalt-iron-based catalysts.

Tuning reactivity of Fischer-Tropsch synthesis by regulating TiOx overlayer over Ru/TiO2 nanocatalysts.

The activity of Fischer-Tropsch synthesis (FTS) on metal-based nanocatalysts can be greatly promoted by the support of reducible oxides, while the role of support remains elusive. Herein, by varying the reduction condition to regulate the TiOx overlayer on Ru nanocatalysts, the reactivity of Ru/TiO2 nanocatalysts can be differentially modulated. The activity in FTS shows a volcano-like trend with increasing reduction temperature from 200 to 600 °C. Such a variation of activity is characterized to be related to the activation of CO on the TiOx overlayer at Ru/TiO2 interfaces. Further theoretical calculations suggest that the formation of reduced TiOx occurs facilely on the Ru surface, and it involves in the catalytic mechanism of FTS to facilitate the CO bond cleavage kinetically. This study provides a deep insight on the mechanism of TiOx overlayer in FTS, and offers an effective approach to tuning catalytic reactivity of metal nanocatalysts on reducible oxides.