Theoretical investigation of layered zeolite frameworks: Interaction between IPC-1P layers derived from zeolite UTL

Interaction between layers of layered zeolite framework IPC-1P was investigated computationally. The inter-layer interaction is controlled by inter-layer hydrogen bonds formed between silanols on adjacent layers. Due to a relatively large concentration of surface silanols in IPC-1P the inter-layer hydrogen bonds account for about 80% of inter-layer interactions. Large number of possible arrangements of neighboring layers exist; the stability of individual arrangements depends primarily on the number of inter-layer hydrogen bonds and their strength. The most stable structure is formed when silanol groups are all parallel with the ac plane and forming a hydrogen-bonded analogue of 10R channel along b direction. Several different arrangements were found with similar interaction energies (within 2.5 kJ mol(-1) per surface silanol). The reliability of computational methods was also investigated. The non-local vdW-DF2 exchange-correlation functional was found to give very accurate description of inter-layer interactions. (C) 2012 Elsevier B.V. All rights reserved.