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Improving the Stability of CeO2 Catalyst by Rare Earth Metal Promotion and Molecular Insights in the Dimethyl Carbonate Synthesis from CO2 and Methanol with 2-Cyanopyridine
ACS Catalysis ( IF 12.9 ) Pub Date : 2018-03-05 00:00:00 , DOI: 10.1021/acscatal.7b04198
Dragos Stoian 1, 2 , Francisco Medina 2 , Atsushi Urakawa 1
Affiliation  

The unmatched efficiency of the direct dimethyl carbonate (DMC) synthesis from CO2 and methanol over CeO2 catalysts in the presence of an organic dehydrating agent (2-cyanopyridine, 2-CP) was recently reported with high DMC yield (>90%) in both batch and continuous operations. However, the CeO2 catalyst gradually deactivates in the time scale of days due to suggested surface poisoning by 2-picolinamide (2-PA) produced by hydration of 2-CP. This work seeks active and stable CeO2-based catalysts and aims to understand the material factors influencing the catalytic performance. Surface modification of CeO2 by the addition of rare earth metal (REM) was found to be effective for improving the catalyst stability. Surface basicity and reducibility of the Ce4+ species play important roles in preventing catalyst deactivation by stabilizing the reactive methoxy species in comparison to the poisoning species (2-PA or species alike). This has been evidenced by in situ attenuated total reflection infrared spectroscopy. CeO2 materials promoted with 1 wt % rare earth metals (La, Gd, and Pr) greatly enhanced the catalyst stability while retaining the high catalytic activity of CeO2. Among them, 1 wt % Pr promotion to CeO2 was the most effective, affording 35% higher DMC yield in comparison to that of bare CeO2 after 150 h on stream under the optimized reaction conditions of 30 bar and 120 °C.

中文翻译:

通过稀土金属促进提高CeO 2催化剂的稳定性,以及使用2-氰基吡啶从CO 2和甲醇合成碳酸二甲酯中的分子洞察力

最近报道了在有机脱水剂(2-氰基吡啶,2-CP)存在下,由CeO 2催化剂由CO 2和甲醇直接合成碳酸二甲酯(DMC)具有无与伦比的效率,且DMC收率高(> 90%)在批处理和连续操作中。然而,由于建议的2-CP水合产生的2-吡啶甲酸酰胺(2-PA)引起的表面中毒,CeO 2催化剂在几天的时间内逐渐失活。这项工作寻求活性和稳定的CeO 2基催化剂,并旨在了解影响催化性能的物质因素。CeO 2的表面改性发现通过添加稀土金属(REM)可有效提高催化剂的稳定性。与中毒物质(2-PA或类似物质)相比,Ce 4+物质的表面碱性和可还原性在通过稳定反应性甲氧基物质来防止催化剂失活方面起着重要作用。这已经通过原位衰减全反射红外光谱法得到了证明。以1 wt%的稀土金属(La,Gd和Pr)促进的CeO 2材料大大提高了催化剂的稳定性,同时保留了CeO 2的高催化活性。其中,最有效的Pr提升为CeO 2的1 wt%,与裸CeO 2相比,DMC的产率提高了35%。 在30 bar和120°C的最佳反应条件下,连续运行150小时后。
更新日期:2018-03-05
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