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DFT study of ethanol dehydration catalysed by hematite

机译：赤铁矿催化乙醇脱水的DFT研究

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Hematite (alpha-Fe2O3) has been used as an ethanol gas sensor and as a catalyst for nanomaterial synthesis, motivating the investigation of ethanol dehydration over a hematite surface using computational chemistry methods. Using a molecular approach and a simple model for alpha-Fe2O3 to mimic the catalyst effect on the thermodynamics and kinetics of the reaction and quantum chemical Density Functional Theory (DFT) calculations, we showed that the energy barrier for the formation of ethylene plus water is around 70% lower than the corresponding gas phase value and that the products are thermodynamically stable with respect to the ethanol reactant in the presence of a non-planar model catalyst (Fe10O15). This stimulating result supports a mechanism proposed for ethylene formation at mild temperatures using hematite as a catalyst. We also showed that the effect of a catalyst on a chemical process can be very satisfactorily simulated as a local effect through first principles quantum chemical calculations, being of practical use, and so, large cluster calculations with many atomic layers or the use of large periodic super cells are not strictly required to reach reasonable estimates of temperature dependent rate constants and products stabilization. Our results strongly support a proposal that the main intermolecular interactions between the species present in a chemical process and the catalyst, leading to stabilization of transition state structure and consequent reduction of energy barrier can be fairly described by the DFT level of theory using small molecular models based on sound chemical ground.
机译：赤铁矿（α-Fe2O3）已被用作乙醇气体传感器和纳米材料合成的催化剂，从而激发了使用计算化学方法研究赤铁矿表面乙醇脱水的研究。使用分子方法和简单的α-Fe2O3模型来模拟催化剂对反应的热力学和动力学的影响以及量子化学密度泛函理论（DFT）的计算，我们证明了形成乙烯加水的能垒是在非平面模型催化剂（Fe10O15）存在下，其相对于乙醇反应物而言，比相应的气相值低约70％，并且该产物相对于乙醇反应物是热力学稳定的。该刺激结果支持了提出的在赤铁矿作为催化剂的温和温度下形成乙烯的机理。我们还表明，通过第一原理量子化学计算，催化剂对化学过程的影响可以非常令人满意地模拟为局部效应，具有实际用途，因此，具有许多原子层的大簇计算或使用大周期性并非严格要求超级电池达到温度依赖性速率常数和产物稳定性的合理估计值。我们的结果有力地支持了这样的建议：化学过程中存在的物种与催化剂之间的主要分子间相互作用，可导致过渡态结构的稳定化，从而降低能垒，可以通过使用小分子模型的DFT理论水平来描述。基于良好的化学基础。

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