Attrition resistances and mechanisms of three types of FCC catalysts

Abstract

Attrition tests of three fluid catalytic cracking (FCC) catalyst samples, named here as sample A, B and C, were carried out in an ASTM (American Society for Testing and Materials) design fluidized bed test unit. The results showed sample A is the most easy to be attrited while sample B has the best attrition resistance. Factors which affect the attrition characteristics including hardness, mechanical strength and surface properties were investigated with particle size distribution (PSD) analysis, scanning electron microscope (SEM), nanoindentation and particle strength tests. The results of the PSD test showed that the attrition mechanisms of the three samples were a mixture of abrasion and fragmentation. Fragmentation of samples B and C was more severe than that of sample A. The nanoindentation and particle strength tests proved that hardness and mechanical strength are the dominant factors of attrition resistances. The combination of attrition tests, SEM images and PSD analyses showed that surface properties such as shapes and surface roughness have weak impacts on attrition resistance, but they can influence attrition mechanisms. Fragmentation was found to occur to particles which have irregular shapes while abrasion generally takes place when surfaces are rough. These findings are important for the manufacture of some solid catalysts.