Interzeolite transformation through cross-nucleation

Polymorph selection and efficient crystallization are cen-tral goals in zeolite synthesis. Crystalline seeds are used for both purposes. The seed’s crystal structure may not always match the daughter zeolite’s. For example, zeolite CHA seeds speed-up 24-fold zeolite AFI’s synthesis. It was proposed that structural elements in CHA promote AFI nucleation. However, these zeolites do not have a common crystal plane or composite building units (CBUs). Here we present the first molecularly resolved investigation of mechanism of seed assisted zeolite syn-thesis. We use molecular simulations to elucidate how CHA promotes AFI. Consistent with experiments, we find that CHA increases AFI’s nucleation 24-fold. The speed up arises from cross-nucleation of AFI on the (001) face of CHA. The CHA/AFI interface is connected by an interfacial transition layer with order distinct from par-ent and daughter. We find that stand-alone CBUs of CHA do not assist in AFI nucleation, implying that the integrity of the crystalline seed is key for increased effi-ciency and selectivity in zeolite synthesis.