Zhang Yaoyuan, Wu Qin, Zhang Kun, Shi Daxin, Jia Shujun, Chen Kangcheng, Li Hansheng
Beijing Key Laboratory for Chemical Power Source and Green Catalysis, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
Langmuir. 2023 Mar 7;39(9):3494-3501. doi: 10.1021/acs.langmuir.3c00028. Epub 2023 Feb 21.
Alkane catalytic cracking is regarded as one of the most significant processes for light olefin production; however, it suffers from serve catalyst deactivation due to coke formation. Herein, HZSM-5/MCM-41 composites with different Si/Al ratios were first prepared by the hydrothermal method. The physicochemical properties of the prepared catalysts were analyzed by a series of bulk and surface characterization methods, and the catalytic performance was tested in -decane catalytic cracking. It was found that HZSM-5/MCM-41 showed a higher selectivity to light olefins and a lower deactivation rate compared with the parent HZSM-5 due to an enhanced diffusion rate and decreased acid density. Moreover, the structure-reactivity relationship revealed that conversion, light olefin selectivity, and the deactivation rate strongly depended on the total acid density. Furthermore, HZSM-5/MCM-41 was further extruded with γ-AlO to obtain the catalyst pellet, which showed an even higher selectivity to light olefins (∼48%) resulting from the synergy effect of the fast diffusion rate and passivation of external acid density.
烷烃催化裂化被认为是生产轻质烯烃最重要的工艺之一；然而，由于焦炭形成，它存在严重的催化剂失活问题。在此，首先通过水热法制备了不同硅铝比的HZSM-5/MCM-41复合材料。通过一系列体相和表面表征方法分析了所制备催化剂的物理化学性质，并在正癸烷催化裂化中测试了其催化性能。结果发现，与母体HZSM-5相比，HZSM-5/MCM-41对轻质烯烃具有更高的选择性和更低的失活速率，这是由于扩散速率提高和酸密度降低所致。此外，结构-反应性关系表明，转化率、轻质烯烃选择性和失活速率强烈依赖于总酸密度。此外，将HZSM-5/MCM-41与γ-AlO进一步挤出以获得催化剂颗粒，由于快速扩散速率和外部酸密度钝化的协同效应，该颗粒对轻质烯烃表现出更高的选择性（约48%）。
