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Activity Promotion of Rh8–xCoxP4 Bimetallic Phosphides in Styrene Hydroformylation: Dual Influence of Adsorption and Surface Reaction
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-07-20 , DOI: 10.1021/acscatal.1c02014 Boyang Liu 1 , Yu Wang 1 , Ning Huang 1 , Xiaocheng Lan 1 , Tiefeng Wang 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-07-20 , DOI: 10.1021/acscatal.1c02014 Boyang Liu 1 , Yu Wang 1 , Ning Huang 1 , Xiaocheng Lan 1 , Tiefeng Wang 1
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The development of a highly active heterogeneous catalyst for styrene hydroformylation is a major challenge, and we previously found that Rh2P was a good candidate. By doping a second metal of Co, we further improved the activity by 1.7 times, and the highest TOF reached 2563 h–1 on Rh7Co1P4/SiO2. The addition of Co tuned the electronic environment of surface Rh atoms without changing the crystal structure, and the reaction activity showed a volcano relationship with the Co ratio. DFT calculations showed that Co doping decreased the overall activation energy of surface reactions and destabilized H2 adsorption simultaneously. When x ≤ 2 for Rh8–xCoxP4/SiO2 catalysts, surface Rh atoms had positive valence and H2 adsorption was exothermic. Therefore, the hydroformylation rate was mainly determined by surface reaction with a first order of styrene concentration. When x > 2, however, surface Rh atoms were negatively charged and H2 adsorption became thermodynamically unfavorable. The reaction activity was then determined by H2 adsorption and was independent of styrene concentration. We introduced δE, which was the sum of overall activation energy and H2 coadsorption energy with styrene, to predict activity. Moderate addition of Co decreased the value of δE and promoted the activity, while excessive doping would increase δE.
中文翻译：
Rh8-xCoxP4 双金属磷化物在苯乙烯加氢甲酰化中的活性促进：吸附和表面反应的双重影响
开发用于苯乙烯加氢甲酰化的高活性多相催化剂是一项重大挑战，我们之前发现 Rh 2 P 是一个很好的候选者。通过掺杂第二种金属 Co，我们将活性进一步提高了 1.7 倍，在 Rh 7 Co 1 P 4 /SiO 2上的最高 TOF 达到了 2563 h –1。Co的加入在不改变晶体结构的情况下调整了表面Rh原子的电子环境，反应活性与Co比例呈火山关系。DFT 计算表明，Co 掺杂降低了表面反应的总活化能，同时破坏了 H 2吸附。当x对于Rh 8– x Co x P 4 /SiO 2催化剂≤ 2 ，表面Rh 原子具有正价并且H 2吸附是放热的。因此，加氢甲酰化速率主要取决于与一级苯乙烯浓度的表面反应。然而，当x > 2 时，表面Rh 原子带负电，H 2吸附在热力学上变得不利。然后通过H 2吸附确定反应活性并且与苯乙烯浓度无关。我们引入了δ E，它是总活化能和 H 2的总和与苯乙烯的共吸附能，以预测活性。Co的适量添加降低了δ E的值并促进了活性，而过度掺杂会增加δ E。
更新日期：2021-08-07
中文翻译：
Rh8-xCoxP4 双金属磷化物在苯乙烯加氢甲酰化中的活性促进：吸附和表面反应的双重影响
开发用于苯乙烯加氢甲酰化的高活性多相催化剂是一项重大挑战，我们之前发现 Rh 2 P 是一个很好的候选者。通过掺杂第二种金属 Co，我们将活性进一步提高了 1.7 倍，在 Rh 7 Co 1 P 4 /SiO 2上的最高 TOF 达到了 2563 h –1。Co的加入在不改变晶体结构的情况下调整了表面Rh原子的电子环境，反应活性与Co比例呈火山关系。DFT 计算表明，Co 掺杂降低了表面反应的总活化能，同时破坏了 H 2吸附。当x对于Rh 8– x Co x P 4 /SiO 2催化剂≤ 2 ，表面Rh 原子具有正价并且H 2吸附是放热的。因此，加氢甲酰化速率主要取决于与一级苯乙烯浓度的表面反应。然而，当x > 2 时，表面Rh 原子带负电，H 2吸附在热力学上变得不利。然后通过H 2吸附确定反应活性并且与苯乙烯浓度无关。我们引入了δ E，它是总活化能和 H 2的总和与苯乙烯的共吸附能，以预测活性。Co的适量添加降低了δ E的值并促进了活性，而过度掺杂会增加δ E。
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