Bores Cecilia, Luo Song, David Lonergan J, Richardson Eden, Engstrom Alexander, Fan Wei, Auerbach Scott M
Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-0304, USA.
Department of Chemical Engineering, University of Massachusetts Amherst, 686 N Pleasant St, Amherst, MA 01003, USA.
Phys Chem Chem Phys. 2021 Dec 22;24(1):142-148. doi: 10.1039/d1cp03913j.
We investigated the influence of organic structure-directing agents (OSDAs) on the formation rates of all-silica zeolite LTA using both simulations and experiments, to shed light on the crystallization process. We compared syntheses using one OSDA with a diameter close to the size of the large cavity in LTA, and two OSDAs of diameters matching the sizes of both the small and large LTA cavities. Reaction-ensemble Monte Carlo (RxMC) simulations predict a speed up of LTA formation using two OSDAs matching the LTA pore sizes; this qualitative result is confirmed by experimental studies of crystallization kinetics, which find a speedup in all-silica LTA crystallization of a factor of 3. Analyses of simulated rings and their Si-O-Si angular energies during RxMC crystallizations show that all ring sizes in the faster crystallization exhibit lower angular energies, on average, than in the slower crystallization, explaining the origin of the speedup through packing effects.
我们通过模拟和实验研究了有机结构导向剂（OSDA）对全硅型LTA沸石形成速率的影响，以阐明其结晶过程。我们比较了使用一种直径接近LTA大孔尺寸的OSDA，以及两种直径分别与LTA小孔和大孔尺寸匹配的OSDA的合成情况。反应系综蒙特卡罗（RxMC）模拟预测，使用两种与LTA孔径匹配的OSDA可加快LTA的形成；结晶动力学的实验研究证实了这一定性结果，该研究发现全硅型LTA结晶速度加快了3倍。对RxMC结晶过程中模拟环及其Si-O-Si角能的分析表明，较快结晶过程中的所有环尺寸平均而言比较慢结晶过程中的角能更低，这通过堆积效应解释了加速的原因。
