CUPRIC ION LOCATION AND ADSORBATE INTERACTIONS IN CU(II) EXCHANGED ERIONITE-LIKE SAPO-17 MOLECULAR SIEVE

摘要

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 P-31 ESEM spectrum suggest that the hydrated Cu(II) complex, Cu-II(H2O)(6), is located in the erionite supercage. During dehydration some of the bare Cu(IT) ions migrate into the smaller cancrinite cage. Room temperature adsorption of D2O on CuH-SAPO-17 after dehydration at 723 K and subsequent O-2 treatment and evacuation at the same temperature (activation) forms a Cu-aquo complex with axially symmetric ESR parameters (g(parallel to) = 2.391 and A(parallel to) = 0.0142 cm(-1)). This complex is suggested to be Cu-II(D2O)(3) based on D-2 ESEM data. Adsorption of ND3 on activated CuH-SAPO-17 produces Cu-II(ND3)(3) with axially symmetric ESR parameters (g(parallel to) = 2.342 and A(parallel to) = 0.0184 cm(-1)). When CD3OH is adsorbed on CuH-SAPO-17, the complex formed with ESR parameters g(parallel to) = 2.327 and A(parallel to) = 0.0125 cm(-1) is found to contain two methanol molecules coordinating directly with the metal ion. Adsorption of C2D4 on activated CuH-SAPO-17 gives an ESR signal characterized by orthorhombic g-values and the complex is suggested to be Cu-II(C2D4)(1) based on ESEM data. [References: 30]