NMR techniques for studying the coking of zeolite-based catalysts

This article is a brief review of the state of the art in the use of Nuclear Magnetic Resonance for studying deactivation of zeolite based catalysts which occurs during cracking, hydrocracking, reforming and isomerization reactions. C-13, Si-29, Al-27, H-1 and Xe-129 are the nuclei studied to obtain information about the nature of the coke, pore blocking, location of the coke, diffusion of reactants, loss of crystallinity, or appearance of defects after coking. Sophisticated techniques such as CP/MAS, DOR (double rotation) or NMR imaging can enhance resonance lines or directly visualize the coke profile in a deactivated coked sample.