IR spectroscopic study of CD3CN adsorbed on ALPO-18 molecular sieve and the solid acid catalysts SAPO-18 and MeAPO-18

Abstract

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 Co^II(in CoAPO-18) and Mg^II(in MgAPO-18) centres exhibits bands at 2310–2305 and 2306–2302 cm^–1, respectively. There are two types of Zn^II 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 Al^III Lewis sites and (P)—OH groups were also observed.