Integrated Laser and Electron Microscopy Correlates Structure of Fluid Catalytic Cracking Particles to Brønsted Acidity

Abstract

Fluid catalytic cracking (FCC) is the main industrial process used worldwide to convert crude oil fractions into fuels and important base chemicals, such as light olefins.[1] This is achieved by using micron-sized spherical catalyst particles of complex composition. Zeolitic material, usually zeolite Y, is the main acidic active cracking ingredient and it is embedded in a matrix consisting of clay, silica, and alumina. Fluorescence microscopy (FM) experiments made major contributions to the visualization and investigation of active sites within heterogeneous catalyst materials.[2] Confocal FM, for instance, was employed to selectively visualize the active zeolite component within FCC catalyst particles.[3] However, FM has limited spatial resolution and solely reveals fluorescent structures. Electron microscopy (EM), on the other hand, allows for high-resolution imaging of nanometer-sized structural details of the sample without the use of probe molecules.[4] Unlike FM, EM does not enable identification of the active areas in the FCC particles. Therefore, we combine the strengths of both FM and EM in the characterization of FCC particles.