Highly Active Ir/In2O3 Catalysts for Selective Hydrogenation of CO2 to Methanol: Experimental and Theoretical Studies,ACS Catalysis

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Highly Active Ir/In2O3 Catalysts for Selective Hydrogenation of CO2 to Methanol: Experimental and Theoretical Studies
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-03-16 , DOI: 10.1021/acscatal.0c05628
Chenyang Shen ₁ , Kaihang Sun ₁ , Zhitao Zhang ₁ , Ning Rui ₁ , Xinyu Jia ₁ , Donghai Mei ₂ , Chang-jun Liu ₁

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Iridium (Ir) catalysts have been extensively applied in homogeneous and photocatalytic CO₂ conversion. However, CO₂ hydrogenation to methanol over the supported Ir catalyst in a heterogeneous flowing reactor has not been reported yet. Here, we report that indium oxide supported Ir catalyst (Ir/In₂O₃) of high dispersion is very active for CO₂ hydrogenation to methanol. Compared to In₂O₃, Ir/In₂O₃ shows a significantly higher activity with even higher methanol selectivity. For example, CO₂ conversion of 17.7% is achieved on Ir/In₂O₃ of 10 wt % Ir loading with methanol selectivity over 70% and high methanol space time yield of 0.765 g_MeOH h^–1 g_cat^–1 at 4/1 of the CO₂/H₂ feed ratio, 21 000 h^–1, 300 °C, and 5 MPa. With the catalysts tested, the higher Ir loading causes the higher activity. The catalyst characterization confirms an intense interaction between iridium and In₂O₃, which causes the high dispersion of the Ir catalyst with the Ir–In₂O₃ interface as the active site for selective hydrogenation of CO₂ into methanol. The Ir loading not only enhances the formation of oxygen vacancies but also stabilizes the vacancies for improved CO₂ activation. Further density functional theory studies reveal that the reverse water–gas shift route is more favorable over the formate route for CO₂ hydrogenation to methanol over Ir/In₂O₃ catalyst.

中文翻译：

用于将CO ₂选择性加氢为甲醇的高活性Ir / In ₂ O ₃催化剂：实验和理论研究

铱（Ir）催化剂已广泛应用于均相和光催化CO ₂转化中。然而，尚未报道在非均相流动反应器中通过负载的Ir催化剂将CO ₂加氢成甲醇。在这里，我们报道了高分散度的氧化铟负载的Ir催化剂（Ir / In ₂ O ₃）对于将CO ₂加氢为甲醇非常活泼。与In ₂ O ₃相比，Ir / In ₂ O ₃表现出明显更高的活性，甚至具有更高的甲醇选择性。例如，在Ir / In ₂ O ₃上实现了17.7％的CO ₂转化率的10重量％的Ir装载用甲醇选择性超过70％和高的甲醇时空收率0.765克_MeOH中ħ ^-1克_猫^-1在CO的4/1 ₂ / H ₂的进料比，21 000小时^-1，300 °C和5 MPa。使用测试的催化剂，较高的Ir负载量导致较高的活性。催化剂的表征证实了铱与In ₂ O ₃之间的强烈相互作用，这导致具有Ir–In ₂ O ₃界面作为CO ₂选择性加氢活性位点的Ir催化剂的高度分散。转化为甲醇。Ir负载不仅增强了氧空位的形成，而且稳定了空位以改善CO ₂活化。进一步的密度泛函理论研究表明，与Ir / In ₂ O ₃催化剂相比，CO ₂加氢制甲醇的甲酸盐路线比水路线更有利。

更新日期：2021-04-02

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