CO₂ hydrogenation to methanol is an effective way to convert CO₂ into useful chemicals and fuel. Recently, some of metal-doped zirconia solid-solutions exhibit high selectivity and activity for CO₂ hydrogenation to methanol. Herein, we report a mechanistic study of the process on MZrO_x (M = Ga, Cr) using density functional calculations and microkinetic simulations. It is found that the pathway for methanol formation is → COOH* → HCOOH* → CHO* → CH₂O* → CH₂OH* → CH₃OH* and HCOOH* → CHO* + OH* is the rate-controlling step on both catalysts. The calculated methanol selectivity agrees with the experimental results very well, supporting the mechanism identified. Investigations show that the influence of strain on reaction kinetics and thermodynamics is not “black or white”: while compressive strain greatly promotes the activity and selectivity of GaZrO_x, both tensile and compressive strains suppress the catalytic performance of CrZrO_x. Analysis also reveals that there is a good transition state scaling (TSS) relation and strain tends to degrade the linear correlation. Furthermore, the error of the predicted barriers using the TSS relation is relatively large, indicating that cautions should be taken when applying TSS relations to estimate barriers.

中文翻译：

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MZrOx (M = Ga, Cr)固溶体催化剂上CO2加氢生成CH3OH的机理及晶格应变的影响

CO _{2加氢制甲醇是将CO 2}转化为有用化学品和燃料的有效途径。近年来，一些金属掺杂氧化锆固溶体对CO ₂加氢制甲醇表现出高选择性和活性。在此，我们报告了使用密度泛函计算和微动力学模拟对 MZrO _x (M = Ga, Cr)过程的机理研究。研究发现甲醇生成路径为→ COOH* → HCOOH* → CHO* → CH ₂ O* → CH ₂ OH* → CH ₃ OH*，其中 HCOOH* → CHO* + OH* 为反应速率控制步骤两者都是催化剂。计算出的甲醇选择性与实验结果非常吻合，支持了所确定的机制。研究表明，应变对反应动力学和热力学的影响并不是“黑白分明”的：虽然压缩应变极大地促进了GaZrO _{x的活性和选择性，但拉伸应变和压缩应变均抑制了CrZrO x}的催化性能。分析还表明，存在良好的过渡态标度（TSS）关系，并且应变往往会降低线性相关性。此外，利用TSS关系预测障碍的误差较大，表明应用TSS关系估计障碍时应谨慎。