Design of Rh catalyst by controlling crystal phase and facet is significant for providing higher mass-specific activity and selectivity for ethanol synthesis from syngas. We demonstrate here the roles of crystal phase and facet in syngas conversion to ethanol on different crystal facets of fcc and hcp Rh by DFT calculations and microkinetic modeling. Compared to hcp Rh, fcc Rh not only exhibits higher intrinsic activity for CH and ethanol formation, but also exposes much denser active facets and inhibits methanol, especially, the mainly exposed (1 1 1). Further, for the Fe-modified Rh catalysts, fcc Rh exhibits better activity and selectivity toward ethanol, which is still superior to hcp Rh. Thus, Rh-based catalysts should be focused on the fcc crystal phase instead of hcp crystal phase. The findings in this work are significantly beneficial to the rational design of Rh-based catalysts for CO hydrogenation to desired ethanol.

通过控制晶相和晶面设计 Rh 催化剂对于为合成气合成乙醇提供更高的质量比活性和选择性具有重要意义。我们在这里通过 DFT 计算和微动力学模型证明了晶相和晶面在 fcc 和 hcp Rh 的不同晶面上的合成气转化为乙醇中的作用。与 hcp Rh 相比，fcc Rh 不仅对 CH 和乙醇的形成表现出更高的内在活性，而且暴露出更致密的活性面并抑制甲醇，尤其是主要暴露的 (1  1 1）。此外，对于Fe修饰的Rh催化剂，fcc Rh对乙醇表现出更好的活性和选择性，仍然优于hcp Rh。因此，Rh 基催化剂应侧重于 fcc 晶相而不是 hcp 晶相。这项工作的发现对合理设计用于将 CO 加氢成所需乙醇的 Rh 基催化剂具有重要意义。