Gas-phase indirect oxidative carbonylation of methanol to dimethyl carbonate (DMC) has been industrialized, but the reaction mechanism is still ambiguous. In this work, the reaction mechanism of DMC synthesis using a NaY zeolite catalyst doped with 1.0 wt% Pd was revealed by combining in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results with density functional theory (DFT) calculations. Two key reaction intermediates CO* (*, a surface site) and COOCH₃* were identified through the adsorption of a probe molecule of methyl chloroformate (CH₃OCOCl), and characterized by steady-state, dynamic-pulse and time-resolved transient DRIFTS experiments. The CO* intermediate is predominant on the catalyst surface when the reaction reached steady-state. The DFT results also showed that the inclusion of OCH₃* into CO* had the highest energy barrier of 150.1 kJ mol⁻¹. This verified that the formation of COOCH₃* is the rate-determining step for the DMC synthesis. A Langmuir-Hinshelwood mechanism including the fast formation of CO*, and rate-determining insertion of OCH₃* into CO* toward generation of COOCH₃* to yield DMC was proposed.

甲醇气相间接氧化羰基化制碳酸二甲酯（DMC）已实现工业化，但反应机理尚不明确。在这项工作中，通过将原位漫反射红外傅里叶变换光谱 (DRIFTS) 结果与密度泛函理论 (DFT) 计算相结合，揭示了使用掺杂 1.0 wt% Pd 的 NaY 沸石催化剂合成 DMC 的反应机理。通过吸附氯甲酸甲酯（_{CH 3}OCOCl)，并以稳态、动态脉冲和时间分辨瞬态漂移实验为特征。当反应达到稳态时，CO* 中间体在催化剂表面占优势。DFT结果还表明，将OCH ₃ * 包含在CO* 中具有最高的能垒，为150.1 kJ mol ^-1。这证实了COOCH ₃ * 的形成是DMC合成的速率决定步骤。提出了一种 Langmuir-Hinshelwood 机制，包括 CO* 的快速形成，以及 OCH ₃ * 到 CO* 中的速率决定性插入，以产生 COOCH ₃ * 以产生 DMC。