Synthesis course of the Ni-SAPO-34 catalyst for methanol-to-olefin conversion

Electronic spectra of Ni-SAPO-34 catalysts prepared by the rapid crystallization method, which show high performance in methanol conversion (i.e., ca. 90% ethylene selectivity with 100% conversion of methanol), suggest that the nickel ions are tetrahedrally coordinated with oxygen and are incorporated into the framework of SAPO-34. Nuclear magnetic resonance and electronic spectra as well as elemental analyses of samples quenched at various temperatures during temperature-programmed hydrothermal crystallization of the rapid crystallization method suggest that the aluminophosphate-like framework is developed first, the silicon atoms then being gradually incorporated into the framework, and the nickel ions falling into the tetrahedral sites at the last stage of crystallization. (C) 1999 Elsevier Science B.V. All rights reserved.