IR spectroscopic study of CD3CN adsorbed on ALPO-18 molecular sieve and the solid acid catalysts SAPO-18 and MeAPO-18
CD3CN has been used as an IR spectroscopic probe to elucidate the nature of the Brønsted and Lewis acid sites in ALPO-18, SAPO-18 and MeAPO-18 (Me = Co, Mg and Zn) microporous materials. Interaction of CD3CN with (Si)–OH–(Al) bridging hydroxy groups in SAPO-18 gives rise to CN absorption bands at 2291 and 2284 cm–1, whereas CD3CN bound to CoII(in CoAPO-18) and MgII(in MgAPO-18) centres exhibits bands at 2310–2305 and 2306–2302 cm–1, respectively. There are two types of ZnII centres in ZnAPO-18, one of which is associated with a CN band at 2316 cm–1 and the other at 2306–2303 cm–1. Interactions between CD3CN and strong/weak AlIII Lewis sites and (P)—OH groups were also observed.