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Reaction-driven selective CO2 hydrogenation to formic acid on Pd(111)
Physical Chemistry Chemical Physics ( IF 3.3 ) Pub Date : 2022-06-09 , DOI: 10.1039/d2cp01971j
Hong Zhang 1 , Xuelong Wang 2 , Ping Liu 1, 2
Affiliation  

Conversion of CO2 to useful fuels and chemicals has gained great attention in the past decades; yet the challenge persists due to the inert nature of CO2 and the wide range of products formed. Pd-based catalysts are extensively studied to facilitate CO2 hydrogenation to methanol via a reverse water gas shift (rWGS) pathway or formate pathway where formic acid may serve as an intermediate species. Here, we report the selective production of formic acid on the stable Pd(111) surface phase under CO2 hydrogenation conditions, which is fully covered by chemisorbed hydrogen, using combined Density Functional Theory (DFT) and Kinetic Monte Carlo (KMC) simulations. The results show that with the full coverage of hydrogen, instead of producing methanol as reported for Pd(111), the CO2 activation is highly selective to formic acid via a multi-step process involving the carboxyl intermediate. The high formic acid selectivity is associated with surface hydrogen species on Pd(111), which not only acts as a hydrogen reservoir to facilitate the hydrogenation steps, but also enables the formation of confined vacancy sites to facilitate the production and removal of formic acid. Our study highlights the importance of reactive environments, which can transform the surface structures and thus tune the activity/selectivity of catalysts.

中文翻译:

Pd(111) 上反应驱动的选择性 CO2 加氢制甲酸

在过去的几十年中,将CO 2转化为有用的燃料和化学品受到了极大的关注。然而,由于 CO 2的惰性和形成的产品范围广泛,挑战依然存在。Pd 基催化剂被广泛研究以通过反向水煤气变换 (rWGS) 途径或甲酸途径促进 CO 2氢化成甲醇,其中甲酸可以作为中间物质。在这里,我们报告了在 CO 2下在稳定的 Pd(111) 表面相上选择性产生甲酸使用组合的密度泛函理论 (DFT) 和动力学蒙特卡罗 (KMC) 模拟,氢化条件完全被化学吸附的氢覆盖。结果表明,在氢气完全覆盖的情况下,CO 2活化对甲酸具有高度选择性,而不是像报道的Pd(111) 那样产生甲醇。涉及羧基中间体的多步骤过程。甲酸的高选择性与 Pd(111) 上的表面氢物种有关,它不仅可以作为氢库来促进氢化步骤,还可以形成受限的空位以促进甲酸的产生和去除。我们的研究强调了反应环境的重要性,它可以改变表面结构,从而调整催化剂的活性/选择性。
更新日期:2022-06-09
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