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 Bronsted 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 C=N 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 C=N 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.