Single-atom catalysis in space: Computational exploration of Fischer-Tropsch reactions in astrophysical environments
Single-atom catalysis in space: Computational exploration of Fischer-Tropsch reactions in astrophysical environments
复制标题
太空中的单原子催化：天体物理环境中费托反应的计算探索
DOI：
10.1051/0004-6361/202347877
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发表时间：
2023
影响因子：
6.5
通讯作者：
Pareras G
中科院分区：
文献类型：
--
作者：
Pareras G
在极端条件下（低密度和温度）的气相化学是困难的，因此星际颗粒的存在对于合成不能在气相中形成的分子特别重要。星际颗粒主张提高其表面上的反应性物种的相遇率，并耗散大量放热反应的能量过剩，但较少有人知道它们作为化学催化剂的作用，提供低活化能的途径，提高反应速率。星际环境中存在不同的具有催化性能的材料，在这项工作中，我们首次报道了在天体物理条件下使用单原子Fe-12-含二氧化硅表面作为星际非均相催化剂。方法考虑扩展周期表面的量子化学计算，寻找反应的驻点和过渡态，最终构造反应势能面。结合能和动力学计算的基础上水稻Ramsperger-Kassel-Marcus（RRKM）计划也进行了评估的催化能力的粮食和分配这些反应过程中的天体化学framework.ResultsOur机制的研究表明，天体催化是可行的天体物理环境。从热力学上讲，所提出的过程主要是放能的，但从动力学上讲，它显示了需要从能量输入中通过的能量障碍。动力学计算还表明，强烈的温度依赖性的反应过程中的隧道效应是不相关的，在所涉及的能量障碍。目前的结果可以解释的存在下，CH 3OH在不同的地区，目前的模型无法重现其观测quantity.ConclusionsThe证据的astrocatalysis开辟了一个全新的光谱的合成路线引发化学演变的空间。从机理的角度来看，由单个原子的Fe 0催化形成甲醇是可行的;然而，它对温度的依赖性使得能量学成为这种情况下的关键问题。
ContextGas-phase chemistry at extreme conditions (low densities and temperatures) is difficult, so the presence of interstellar grains is especially important for the synthesis of molecules that cannot form in the gas phase. Interstellar grains are advocated to enhance the encounter rate of the reactive species on their surfaces and to dissipate the energy excess of largely exothermic reactions, but less is known of their role as chemical catalysts that provide low activation energy pathways with enhanced reaction rates. Different materials with catalytic properties are present in interstellar environments, like refractory grains containing space-abundantd-block transition metals.AimsIn this work we report for first time mechanistic insights on the Fischer–Tropsch methanol (CH3OH) synthesis under astrophysical conditions using single-atom Fe-containing silica surfaces as interstellar heterogeneous catalysts.MethodsQuantum chemical calculations considering extended periodic surfaces were carried out in order to search for the stationary points and transitions states to finally construct the reaction potential energy surfaces. Binding energy and kinetic calculations based on the Rice–Ramsperger–Kassel–Marcus (RRKM) scheme were also performed to evaluate the catalytical capacity of the grain and to allocate those reaction processes within the astrochemical framework.ResultsOur mechanistic studies demonstrate that astrocatalysis is feasible in astrophysical environments. Thermodynamically the proposed process is largely exergonic, but kinetically it shows energy barriers that would need from an energy input in order to go through. Kinetic calculations also demonstrate the strong temperature dependency of the reaction process as tunnelling is not relevant in the involved energetic barriers. The present results can explain the presence of CH3OH in diverse regions where current models fail to reproduce its observational quantity.ConclusionsThe evidence of astrocatalysis opens a completely new spectrum of synthetic routes triggering chemical evolution in space. From the mechanistic point of view the formation of methanol catalysed by a single atom of Fe0is feasible; however, its dependency on the temperature makes the energetics a key issue in this scenario.