一氧化碳有潛力成為通過費-托合成 (FTS) 生產碳氫化合物的替代原油原料。 CO 和 H2 已被用於通過基於Rh 的奈米催化劑有效合成碳氫化合物。不幸的是，如果團簇沒有支撐在基材上，過小的奈米團簇 (原子顆數≤ 20) 的結構將難以定義。並且Rh 奈米團簇在不同載體上的催化活性會明顯不同，因為團簇和載體之間會形成相互作用，這取決於相互作用是產生正向的影響還是負面之影響。 因此我們研究了Rh4 奈米團簇與不同負載物之間的穩定性，並進一步討論了負載物對催化效果的影響。本研究通過 DFT 計算研究了Rh4 奈米團簇接上不同載體，載體為石墨烯(Graphene)、沸石 (ZSM-5)和介孔分子篩(MCM-41)。我們以費托合成出 *CHx 形式的反應機理。 我們研究了*CHxO (x = 1, 2, 3)、*CH4、*CH3OH，在Rh4 以石墨烯為載體、Rh4 以沸石為載體和 Rh4 以介孔分子篩為載體中，氫對輔助解離生成特定*CHx 片段的反應選擇性。 此外，我們還通過電子分析進一步了解了*CHx 片段是如何被不同的載體選擇性穩定的。 最後我們希望通過仔細篩選適當的載體來改變 Rh4 奈米團簇的活性，以幫助開發高選擇性費托合成催化劑，從而實現最佳之能量屏障。
Carbon monoxide is a promising alternative crude oil feedstock for
producing hydrocarbons via Fischer-Tropsch synthesis (FTS). Rh-based
nanocatalysts have been found to efficiently synthesize hydrocarbons from
CO and H2. However, the conformation of small nanoclusters (N ⤠20) is
difficult to define without substrate support. The catalytic activity of Rhnanoclusters on different supports varies significantly due to varied
interactions between cluster and support, inducing either a positive or
negative effect. Therefore, this study investigates the stability of Rh4
nanoclusters on different supports and their influence on catalytic effects.
Using DFT calculations, we systematically study the reaction mechanism
of *CHx formation in Fischer-Tropsch synthesis on Rh4@Supported (Supported = ZSM-5, and MCM-41) and investigate the selectivity of the
hydrogen-assisted dissociation of *CHxO (x = 1 ~ 4) on Rh4@ZSM-5, and
Rh4@MCM-41 to generate specific *CHx fragments. Additionally, we
analyze how different Rh4@Supported selectively stabilize *CHx
fragments through electronic analysis. Ultimately, our goal is to identify the proper support to optimize the activity of Rh4 nanoclusters and develop high selectivity FTS catalysts with an optimal barrier. Based on our findings, Rh4@MCM-41 exhibits the highest selectivity among the chosen Rh4@Supported catalysts. This is due to the superior stability of *CHx (x= 3, 4) fragments on this catalyst, making it an excellent candidate for use in Fischer-Tropsch synthesis. We believe that these results have important implications for the development of high-performance FTS catalysts and suggest that Rh4@MCM-41 should be further investigated as a potential catalyst for industrial applications.
