Fluid catalytic cracking catalyst microstructure as determined by a scanning ion microprobe

Abstract

Zeolite and matrix phases are observed in secondary ion mass spectrometry (SIMS) elemental maps of fluid cracking catalyst microspheres prepared by the in-situ zeolite growth procedure. Digitized high lateral resolution (≈50 nm) analytical SIMS images were obtained with a scanning ion microprobe, and zeolite, matrix and precipitate image subareas were identified and analyzed retrospectively. Zeolite Y regions are differentiated from the calcined aluminosilicate matrix in catalyst microspheres by differences in their silicon and aluminum secondary ion yields. Sodium ion maps show that intrinsic and added sodium counter ions are associated predominantly with the zeolites in non-steamed samples. Catalyst steaming promotes zeolite debris formation and causes sodium repartitioning between the zeolite and matrix phases, increasing sodium concentration in the matrix. The data demonstrate the capabilities of high-resolution imaging SIMS studies of these materials and suggest further investigations of zeolite counter ion migration.