Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan.
Department of Chemistry, National Taiwan Normal University, No. 88, Sec. 4, Ting-Zhou Road, Taipei, Taiwan.
J Chem Phys. 2023 May 7;158(17). doi: 10.1063/5.0151135.
We have studied the decomposition of methanol-d4 on thin film Al2O3/NiAl(100) under near-ambient-pressure conditions, with varied surface-probe techniques and calculations based on density-functional theory. Methanol-d4 neither adsorbed nor reacted on Al2O3/NiAl(100) at 400 K under ultrahigh vacuum conditions, whereas they dehydrogenated, largely to methoxy-d3 (CD3O*, * denoting adsorbates) and formaldehyde-d2 (CD2O*), on the surface when the methanol-d4 partial pressure was increased to 10-3 mbar and above. The dehydrogenation was facilitated by hydroxyl (OH* or OD*) from the dissociation of little co-adsorbed water; a small fraction of CD2O* interacted further with OH* (OD*) to form, via intermediate CD2OOH* (CD2OOD*), formic acid (DCOOH* or DCOOD*). A few surface carbonates were also yielded, likely on the defect sites of Al2O3/NiAl(100). The results suggest that alumina not only supports metal clusters but also participates in reactions under realistic catalytic conditions. One may consider accordingly the multiple functions of alumina while designing ideal catalysts.
我们研究了在近环境压力条件下，薄膜 Al2O3/NiAl(100) 上甲醇-d4 的分解，使用了多种表面探针技术和基于密度泛函理论的计算。在超高真空条件下，甲醇-d4 在 400 K 时既不吸附也不与 Al2O3/NiAl(100) 反应，而当甲醇-d4 的分压增加到 10-3 mbar 及以上时，它们在表面脱氢，主要生成甲氧基-d3 (CD3O*，表示吸附物) 和甲醛-d2 (CD2O)。脱氢由来自少量共吸附水的解离的羟基 (OH* 或 OD*) 促进；一小部分 CD2O* 与 OH* (OD*) 进一步相互作用，通过中间体 CD2OOH* (CD2OOD*) 形成甲酸 (DCOOH* 或 DCOOD*)。还生成了少量的表面碳酸盐，可能在 Al2O3/NiAl(100) 的缺陷位上。结果表明，氧化铝不仅支撑金属簇，而且在实际催化条件下参与反应。在设计理想催化剂时，可以相应地考虑氧化铝的多种功能。
