Catalytic conversion of methane to methanol remains an economically tantalizing but fundamentally challenging goal. Current technologies based on zeolites deactivate too rapidly for practical application. We found that similar active sites hosted in different zeolite lattices can exhibit markedly different reactivity with methane, depending on the size of the zeolite pore apertures. Whereas zeolite with large pore apertures deactivates completely after a single turnover, 40% of active sites in zeolite with small pore apertures are regenerated, enabling a catalytic cycle. Detailed spectroscopic characterization of reaction intermediates and density functional theory calculations show that hindered diffusion through small pore apertures disfavors premature release of CH₃ radicals from the active site after C-H activation, thereby promoting radical recombination to form methanol rather than deactivated Fe-OCH₃ centers elsewhere in the lattice.

甲烷催化转化为甲醇仍然是一个经济上诱人但从根本上具有挑战性的目标。目前基于沸石的技术失活速度太快，无法实际应用。我们发现，不同沸石晶格中的相似活性位点可以表现出与甲烷明显不同的反应性，具体取决于沸石孔径的大小。大孔径沸石在一次周转后会完全失活，而小孔径沸石中 40% 的活性位点会再生，从而实现催化循环。反应中间体的详细光谱表征和密度泛函理论计算表明，通过小孔径的受阻扩散不利于CH活化后CH ₃自由基从活性位点过早释放，从而促进自由基重组形成甲醇，而不是在其他地方失活的Fe-OCH ₃中心在格子里。