Insights into the Selectivity Determinant and Rate-Determining Step of CO2 Hydrogenation to Methanol,The Journal of Physical Chemistry C

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Insights into the Selectivity Determinant and Rate-Determining Step of CO2 Hydrogenation to Methanol
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2022-06-16 , DOI: 10.1021/acs.jpcc.2c02995
Chizhou Tang _{1,

2} , Shan Tang _{1,

2} , Feng Sha _{1,

3} , Zhe Han _{1,

3} , Zhendong Feng _{1,

2} , Jijie Wang ₁ , Can Li ₁

Affiliation

CO₂ hydrogenation to methanol has attracted much attention. The mechanism, the factors affecting selectivity, and the rate-determining step of the reaction have not been clearly concluded. Here, the reaction mechanism on the Cu/ZnO/Al₂O₃, the Pd/ZnO, and the ZnZrO_x catalysts was studied by in situ infrared spectroscopy and HCOOH temperature-programmed surface reaction (HCOOH-TPSR) experiment. It is shown that the HCOO* mechanism is a feasible mechanism, and the more stable HCOO* on the catalysts is, the higher the selectivity of methanol accompanied with the less CO produced via the decomposition of HCOO*. H₂–D₂ isotope exchange reaction is inhibited in the presence of CO₂, which indicates that H₂ activation and H* migration are inhibited by CO₂ adsorbed on the catalysts. As for CO₂ hydrogenation to methanol, the reaction orders of H₂ and CO₂ are close to 0.5 and 0, respectively, indicating that activated H* on the catalysts is insufficient. Comparing CO₂ hydrogenation to methanol reaction and H₂–D₂ isotope exchange reaction, their H₂ reaction orders are both 0.5 and the two reaction rates show a linear relationship when the temperature changes. It is considered that the rate-determining step of CO₂ hydrogenation to methanol is the migration of H* on the catalysts.

中文翻译：

深入了解 CO2 加氢制甲醇的选择性决定因素和速率决定步骤

CO ₂加氢制甲醇备受关注。该反应的机理、影响选择性的因素和限速步骤还没有明确的结论。在此，通过原位红外光谱和HCOOH程序升温表面反应（HCOOH-TPSR）实验研究了Cu/ZnO/Al ₂ O ₃、Pd/ZnO和ZnZrO _{x催化剂的反应机理。}结果表明HCOO*机理是一种可行的机理，HCOO*在催化剂上越稳定，甲醇的选择性越高，同时HCOO*分解产生的CO越少。H ₂ -D ₂同位素交换反应在 CO 存在下受到抑制_如图2所示，表明催化剂上吸附的CO ₂抑制了H _{2活化和H*迁移。}对于CO ₂加氢制甲醇，H ₂和CO ₂的反应级数分别接近0.5和0，表明催化剂上的活化H*不足。将CO ₂加氢与甲醇反应和H ₂ -D ₂同位素交换反应进行比较，它们的H ₂反应级数均为0.5，两种反应速率在温度变化时呈线性关系。认为CO _{2的限速步骤}氢化成甲醇是 H* 在催化剂上的迁移。

更新日期：2022-06-16

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