The dynamics of catechol in zeolite Beta was studied using quesielastic neutron scattering (QENS) experiments and molecular dynamics simulations at 393 K, to understand the behaviour of phenolic monomers relevant in the catalytic conversion of lignin via metal nanoparticles supported on zeolites. Compared to previous work studying phenol, both methods observe that the presence of the second OH group in catechol can hinder mobility significantly, as explained by stronger hydrogen-bonding interactions between catechol and the Brønsted sites of the zeolite. The instrumental timescale of the QENS experiment allows us to probe rotational motion, and the catechol motions are best fit to an isotropic rotation model with a \(D^{rot}\) of 2.9 × 10\(^{10}\) s\(^{-1}\). While this \(D^{rot}\) is within error of that measured for phenol, the fraction of molecules immobile on the instrumental timescale is found to be significantly higher for catechol. The MD simulations also exhibit this increased in ‘immobility’, showing that the long-range translational diffusion coefficients of catechol are lower than phenol by a factor of 7 in acidic zeolite Beta, and a factor of \(\sim\)3 in the siliceous material, further illustrating the significance of Brønsted site H-bonding. Upon reproducing QENS observables from our simulations to probe rotational motions, a combination of two isotropic rotations was found to fit the MD-calculated EISF; one corresponds to the free rotation of catechol in the pore system of the zeolite, while the second rotation is used to approximate a restricted and rapid “rattling”, consistent with molecules anchored to the acid sites through their OH groups, the motion of which is too rapid to be observed by experiment.

使用quesielastic中子散射（QENS）实验和393 K的分子动力学模拟研究了Beta中邻苯二酚的动力学，以了解酚类单体与木质素通过负载在沸石上的金属纳米粒子催化转化有关的行为。与先前研究苯酚的工作相比，两种方法均观察到邻苯二酚中存在第二个OH基团可显着阻碍流动性，这可由邻苯二酚和沸石的Brønsted位点之间更强的氢键相互作用来解释。QENS实验的仪器时间尺度使我们能够探测旋转运动，而邻苯二酚运动最适合2.9×10 \（^ {10} \） s \（D ^ {rot} \）的各向同性旋转模型\（^ {-1} \）。尽管该（D ^ {rot} \）在苯酚测量值的误差范围内，但发现仪器时间尺度上固定的分子分数对于邻苯二酚而言明显更高。MD模拟也显示出这种增加的“固定性”，表明儿茶酚的远程平移扩散系数在酸性沸石Beta中比苯酚低7倍，而\（\ sim \）硅质材料中的图3进一步说明了布朗斯台德位点H键的重要性。从我们的模拟中复制QENS观测值以探测旋转运动后，发现两个各向同性旋转的组合适合MD计算的EISF。第一个旋转对应于邻苯二酚在沸石孔隙系统中的自由旋转，而第二个旋转用于近似受限和快速的“咔嗒作响”，这与通过其OH基团锚定在酸性位点上的分子保持一致太快而无法通过实验观察到。