Cupric Ion Location and Adsorbate Interactions in Cu(II) Exchanged Erionite-like SAPO-17 Molecular Sieve

Abstract

Erionite-like silicoaluminophosphate molecular sieve SAPO-17 has been synthesized using cyclohexylamine as the organic structure directing molecule. The location of Cu(II) ions exchanged into H-SAPO-17 and the interaction of Cu(II) ions with water, ammonia, methanol, and ethylene have been investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) techniques. Simulation parameters of the 31P ESEM spectrum suggest that the hydrated Cu(II) complex, CuII(H2O)6, is located in the erionite supercage. During dehydration some of the bare Cu(II) ions migrate into the smaller cancrinite cage. Room temperature adsorption of D2O on CuH-SAPO-17 after dehydration at 723 K and subsequent O2 treatment and evacuation at the same temperature (activation) forms a Cu−aquo complex with axially symmetric ESR parameters (g|| = 2.391 and A|| = 0.0142 cm-1). This complex is suggested to be CuII(D2O)3 based on 2D ESEM data. Adsorption of ND3 on activated CuH-SAPO-17 produces CuII(ND3)3 with axially sym...