Understanding hydrocarbon generation in the zeolite-catalysed conversions of methanol and methyl chloride requires advanced spectroscopic approaches to distinguish the complex mechanisms governing C–C bond formation, chain growth and the deposition of carbonaceous species. Here operando photoelectron photoion coincidence (PEPICO) spectroscopy enables the isomer-selective identification of pathways to hydrocarbons of up to C₁₄ in size, providing direct experimental evidence of methyl radicals in both reactions and ketene in the methanol-to-hydrocarbons reaction. Both routes converge to C₅ molecules that transform into aromatics. Operando PEPICO highlights distinctions in the prevalence of coke precursors, which is supported by electron paramagnetic resonance measurements, providing evidence of differences in the representative molecular structure, density and distribution of accumulated carbonaceous species. Radical-driven pathways in the methyl chloride-to-hydrocarbons reaction(s) accelerate the formation of extended aromatic systems, leading to fast deactivation. By contrast, the generation of alkylated species through oxygenate-driven pathways in the methanol-to-hydrocarbons reaction extends the catalyst lifetime. The findings demonstrate the potential of the presented methods to provide valuable mechanistic insights into complex reaction networks.

了解沸石催化的甲醇和氯甲烷转化中的烃生成需要先进的光谱方法来区分控制 C-C 键形成、链生长和碳质物质沉积的复杂机制。在这里，操作光电子光离子重合 (PEPICO) 光谱能够对尺寸高达 C ₁₄的烃的途径进行异构体选择性识别，从而为甲醇制烃反应中的甲基自由基和乙烯酮反应提供直接的实验证据。两条路线都汇聚到 C ₅转化为芳烃的分子。Operando PEPICO 强调了焦炭前体普遍存在的差异，这得到了电子顺磁共振测量的支持，为积累的碳质物种的代表性分子结构、密度和分布的差异提供了证据。氯甲烷-烃反应中的自由基驱动途径加速了扩展芳烃体系的形成，导致快速失活。相比之下，在甲醇制烃反应中通过含氧化合物驱动的途径生成烷基化物质可延长催化剂寿命。这些发现证明了所提出的方法有可能为复杂的反应网络提供有价值的机理见解。