On the Removal of Template from Silicalite-1 90° Intergrowths. A Study by X-ray Photoelectron Spectroscopy

Thermal template removal from a surface layer of TPA+−silicalite-1 90° intergrowths, performed in gas flow between 150 and 530 °C, was investigated a posteriori by X-ray photoelectron spectroscopy. In the N 1s photoelectron spectrum the low (L) and the high (H) energy line have been observed. These lines are assigned to TPA+ (H line) and nitrogen-containing products of template degradation (L line), respectively. Two types of template species were distinguished: those physisorbed on the amorphous surface and, on the other hand, those entrapped in the channels of silicalite-1. Linear correlation was established between surface and bulk concentrations of entrapped template species. The products of template removal thus migrate mainly along the boundaries of domains of different crystallographic order.