Department of Chemical Engineering, Center for Catalytic Science and Technology, University of Delaware, Newark, Delaware 19716, USA.
J Chem Phys. 2010 Sep 14;133(10):104702. doi: 10.1063/1.3488056.
The ability to control the bond scission sequence of O-H, C-H, and C-O bonds is of critical importance in the effective utilization of oxygenate molecules, such as in reforming reactions and in alcohol fuel cells. In the current study, we use methanol as a probe molecule to demonstrate the possibility to control the decomposition pathways by supporting monolayer coverage of Pt on a tungsten monocarbide (WC) surface. Density functional theory (DFT) results reveal that on the WC and Pt/WC surfaces CH3OH decomposes via O-H bond scission to form the methoxy (*CH3 O) intermediate. The subsequent decomposition of methoxy on the WC surface occurs through the C-O bond scission to form *CH3, which reacts with surface *H to produce CH4. In contrast, the decomposition of methoxy on the Pt/WC surface favors the C-H bond scission to produce *CH2 O,which prevents the formation of the *CH3 species and leads to the formation of a *CO intermediate through subsequent deprotonation steps. The DFT predictions are validated using temperature programmed desorption to quantify the gas-phase product yields and high resolution electron energy loss spectroscopy to determine the surface intermediates from methanol decomposition on Pt, WC,and Pt/WC surfaces.
控制 O-H、C-H 和 C-O 键键断裂顺序的能力对于有效利用含氧分子（如重整反应和醇燃料电池）至关重要。在目前的研究中，我们使用甲醇作为探针分子，通过在碳化钨（WC）表面上支持单层覆盖的铂来证明控制分解途径的可能性。密度泛函理论（DFT）结果表明，在 WC 和 Pt/WC 表面上，甲醇通过 O-H 键断裂分解形成甲氧基（CH3 O）中间体。随后，WC 表面上甲氧基的分解通过 C-O 键断裂形成CH3，与表面H 反应生成 CH4。相比之下，甲氧基在 Pt/WC 表面上的分解有利于 C-H 键断裂，生成CH2 O，这阻止了CH3 物种的形成，并通过后续的去质子化步骤导致CO 中间体的形成。使用程序升温脱附来量化气相产物产率，以及使用高分辨率电子能量损失光谱来确定甲醇在 Pt、WC 和 Pt/WC 表面上分解的表面中间体，验证了 DFT 预测。
