Secondary-metals promotion is key to tune the CO₂ hydrogenation performance of Rh-based catalyst. We describe the addition of Cu or Co in TiO₂ nanorods supported Rh catalyst (viz., RhM_x/TiO₂), showing significant impact on the CO₂ hydrogenation activity and productivity. Cu addition can promote the partial hydrogenation to alcohols (methanol and ethanol), whereas Co led to the deep hydrogenation to alkanes (CH₄, C₂H₆). Comparative time-resolved in situ DRIFTS studies with H₂/D₂ isotopic exchange further reveal that both surface adsorbed CO* and formates could be the key reaction intermediates during the CO₂ hydrogenation over RhM_x/TiO₂ (especially the RhCu_2.5/TiO₂), in which the interaction strength of CO* regulated by secondary-metals addition was key to tune the reaction pathways and productivity. The findings suggested that rational design of active metal sites, for example the synergy between Rh and secondary-metals, is highly needed to promote the CO insertion and CC coupling to produce ethanol.

中文翻译：

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通过添加仲金属调节 TiO2 纳米棒负载的 Rh 催化剂的 CO2 加氢活性和选择性


再生金属的推广是调整 Rh 基催化剂的 CO₂ 加氢性能的关键。我们描述了在 TiO₂ 纳米棒负载的 Rh 催化剂（即 RhM_x/TiO₂）中添加 Cu 或 Co，显示出对 CO₂ 加氢活性和生产率的显着影响。Cu 添加可促进部分氢化为醇类（甲醇和乙醇），而 Co 导致深度氢化为烷烃（CH₄、C₂H₆）。具有 H₂/D₂ 同位素交换的时间分辨原位 DRIFTS 比较研究进一步表明，表面吸附的 CO* 和甲酸盐都可能是 RhM_x/TiO₂（尤其是 RhCu_2.5/TiO₂）上 CO₂ 加氢过程中的关键反应中间体，其中受仲金属添加调节的 CO* 的相互作用强度是调整反应途径和生产率的关键。研究结果表明，活性金属位点的合理设计，例如 Rh 和仲金属之间的协同作用，对于促进 CO 插入和 CC 耦合产生乙醇是非常必要的。