Selective Methanol Carbonylation to Acetic Acid on Heterogeneous Atomically Dispersed ReO4/SiO2 Catalysts,Journal of the American Chemical Society

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Selective Methanol Carbonylation to Acetic Acid on Heterogeneous Atomically Dispersed ReO4/SiO2 Catalysts
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-07-21 , DOI: 10.1021/jacs.0c05026
Ji Qi ₁ , Jordan Finzel ₁ , Hossein Robatjazi ₁ , Mingjie Xu , Adam S Hoffman ₂ , Simon R Bare ₂ , Xiaoqing Pan , Phillip Christopher ₁

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Methanol carbonylation to acetic acid (AA) is a large-scale commodity chemical production process that requires homogeneous liquid-phase organometallic catalysts with corrosive halide-based co-catalysts to achieve high selectivity and activity. Here we demonstrate a heterogeneous catalyst based on atomically dispersed rhenium (ReO4) active sites on an inert support (SiO2) for the halide-free, gas phase carbonylation of methanol to AA. Atomically dispersed ReO4 species and nanometer sized ReOx clusters were deposited on a high surface area (700 m2/g) inert SiO2 using triethanolamine as a dispersion promoter and characterized using aberration corrected scanning transmission electron microscopy (AC-STEM), UV-Vis spectroscopy and X-ray absorption spectroscopy (XAS). Reactivity measurements at atmospheric pressure with 30 mbar of methanol and CO (1:1 molar ratio) showed that bulk Re2O7¬ and ReOx clusters on SiO2 (formed at > 10 wt.%) were selective for dimethyl ether formation, while atomically dispersed ReO4 on SiO2 (formed at < 10 wt.%) exhibited stable (for 60 hours) > 93% selectivity to AA with single pass conversion > 60%. Kinetic analysis, in-situ FTIR and in-situ XAS measurements suggest that the AA formation mechanism involves methanol activation on ReO4, followed by CO insertion into the terminal methyl species. Further, by introducing ~0.2 wt.% of atomically dispersed Rh to 10 wt.% atomically dispersed ReO4 on SiO2 > 96% selectivity toward AA production at volumetric reaction rates comparable to homogeneous processes were observed. This work introduces a new class of promising heterogeneous catalysts based on atomically dispersed ReO4 on inert supports for alcohol carbonylation.

中文翻译：

在多相原子分散的 ReO4/SiO2 催化剂上选择性甲醇羰基化制乙酸

甲醇羰基化制乙酸 (AA) 是一种大规模商品化学生产过程，需要均相液相有机金属催化剂和腐蚀性卤化物基助催化剂，以实现高选择性和活性。在这里，我们展示了一种基于原子分散的铼 (ReO4) 活性位点在惰性载体 (SiO2) 上的多相催化剂，用于将甲醇无卤化物气相羰基化为 AA。使用三乙醇胺作为分散促进剂，将原子分散的 ReO4 物质和纳米尺寸的 ReOx 簇沉积在高表面积 (700 m2/g) 惰性 SiO2 上，并使用像差校正扫描透射电子显微镜 (AC-STEM)、紫外-可见光谱和X 射线吸收光谱 (XAS)。在大气压下使用 30 mbar 甲醇和 CO 进行反应性测量 (1: 1 摩尔比）表明，SiO2 上的本体 Re2O7 和 ReOx 团簇（以 > 10 wt.% 形成）对二甲醚的形成具有选择性，而在 SiO2 上原子分散的 ReO4（以 < 10 wt.% 形成）表现出稳定（对于 60小时) > 93% 的 AA 选择性，单程转化率 > 60%。动力学分析、原位 FTIR 和原位 XAS 测量表明 AA 形成机制涉及甲醇在 ReO4 上的活化，然后将 CO 插入末端甲基物种。此外，通过在 SiO2 上引入约 0.2 重量％的原子分散的 Rh 到 10 重量％的原子分散的 ReO4，观察到在与均相过程相当的体积反应速率下对 AA 生产的选择性 > 96％。

更新日期：2020-07-21

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