HZSM-5分子筛颗粒的热态流化磨损特性

Thermal fluidized attrition characteristics of HZSM-5 molecular sieve particles

低碳烷烃芳构化反应是煤炭资源清洁利用的标志性技术,但催化剂磨损会降低其反应效率,影响产物质量。因此在不同温度下以0.3 m/s空气流速对不同初始粒径的催化剂颗粒进行16 h流化磨损,分析环境温度对颗粒磨损特性的影响,结合颗粒形貌与粒径变化解释磨损机制与初始粒径间的关系。结果表明:磨损率与环境温度成正比,与初始粒径成反比,当环境温度升高至600℃,颗粒组分结构发生变化,累积磨损率由15%提高至25%;当初始粒度从100μm提高至150μm,累计磨损率降低接近10%。结合粒径分布变化,证明小颗粒磨损以表面剥层为主,大颗粒磨损以体相断裂为主。根据磨损速率与磨损机制的变化可将磨损行为分为高速阶段、减速阶段和匀速阶段,磨损速率在高速阶段达到峰值,催化剂主要发生裂纹增殖与表面剥层,体相断裂仅在减速阶段与表面剥层共同主导磨损。以上研究表明,降低反应温度与增大颗粒粒径均能减少颗粒磨损率,同时以温度与初始粒径为参数建立了磨损模型,有助于预测颗粒磨损进程。

The aromatization reaction of light alkanes represents a revolutionary technology for the clean utilization of coal resources.However,catalyst attrition poses a challenge by diminishing reaction efficiency and compromising product quality.To address this issue,the catalyst particles of varying initial sizes were subjected to fluidized attrition with an apparent air velocity of 0.3 m/s for 16 h at different temperatures.The effect of ambient temperature on particle attrition characteristics was rigorously analyzed and the relationship between attrition mechanisms and initial particle size was elucidated by considering alterations in particle morphology and size.The results show that a directly proportional between attrition ratio and ambient temperature,as well as an inversely proportional with the initial particle size.As the ambient temperature increases to 600℃,structural changes in the particle composition has changed and the cumulative attrition ratio has increased from 15%to 25%.Conversely,increasing the initial particle size from 100μm to 150μm results in a decrease of nearly 10%in cumulative attrition ratio.Examination of the particle size distribution confirms that small particles are primarily influenced by surface exfoliation,while large particles are predominantly affected by bulk phase fracture.Furthermore,the attrition behavior is categorized into high-speed stage,deceleration stage,and uniform-speed stage based on variations in attrition ratio and attrition mechanisms.The attrition ratio peaks at the high-speed stage,to the catalyst mainly under goes crack initiation and surface delamination.Bulk phase fracture only predominantly contributes to particle attrition in the deceleration stage along with surface delamination.Based on these insights,reducing reaction temperature and increasing particle size can both mitigate particle attrition.Meanwhile,an attrition model was developed by incorporating particle temperature and initial particle size as parameters to facilitate the prediction of particle attrition behavior.