Electron Spin Resonance and Electron Spin Echo Modulation Studies of Ion-Exchanged NiH−SAPO-17 and NiH−SAPO-35 Molecular Sieves: Comparison with Ion-Exchanged NiH−SAPO-34 Molecular Sieve

Abstract

Erionite-like silicoaluminophosphate molecular sieve SAPO-17 and levyne-like SAPO-35, in which Ni ions were incorporated via solid-state ion-exchange into known extraframework sites, have been studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM). The Ni ion reducibility, location, and interaction with several adsorbates have been investigated. Among these adsorbates, the interaction with nitric oxide was emphasized and compared to that of Ni ion with NO in the previously studied chabazite-like SAPO-34. Room-temperature adsorption of C2D4 on NiH−SAPO-17 after dehydration at 573 K, oxygen treatment at 823 K, evacuation, and subsequent hydrogen treatment at 573 K produces two Ni−ethylene complexes. Carbon monoxide adsorption gives rise to a Ni(I)−(CO)n complex with unresolved 13C hyperfine lines. Following the kinetics of nitric oxide adsorption on NiH−SAPO-17 shows that initially, a Ni(I)−(NO)+ complex, a NO radical, and a new species which appears to be another NO species are g...