Analysis of HZSM-5 molecular sieve particles attrition behavior under fluidized conditions

Abstract

The attrition behavior of HZSM-5 zeolite catalyst particles at room temperature was investigated in a laboratory-scale fluidized bed. The effects of three fluidization conditions on particle attrition were investigated, and a new attrition model was proposed. The results demonstrate that the attrition rate is inversely proportional to the initial particle size and proportional to the apparent gas velocity. After increasing to 80 μm and .3 m/s respectively, they are no longer the main factor affecting attrition. The effect of bed pressure on attrition rate is nonlinear, and the lowest attrition rate is obtained when the diameter-height ratio is 1:1. Unsteady attrition stage can be divided into initial stage and deceleration stage. Surface delamination dominates particle attrition throughout the whole process, and bulk fracture is the dominant mechanism only in the deceleration stage. Based on the Gwyn equation, a new attrition model in the form of cubic polynomial is established with the ratio of total attrition rate to unstable attrition rate P as a parameter. The model has high accuracy and repeatability and is suitable for various fluidization conditions. It can effectively describe the attrition process and change rule of particles and reasonably predict the fluidization attrition rate of particles.