Effect of metal modification of HZSM-5 on catalyst stability in the shape-selective methylation of toluene
Effect of metal modification of HZSM-5 on catalyst stability in the shape-selective methylation of toluene
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DOI：
10.1016/j.cattod.2009.12.012
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发表时间：
2010-10
期刊：
影响因子：
5.3
通讯作者：
Yan Zhao;Hongyu Wu;W. Tan;Mengmeng Zhang;Min Liu;C. Song;Xiangsheng Wang;Xinwen Guo
中科院分区：
文献类型：
--
作者：
Yan Zhao;Hongyu Wu;W. Tan;Mengmeng Zhang;Min Liu;C. Song;Xiangsheng Wang;Xinwen Guo
在连续流固定床反应器中，采用改性 HZSM-5 催化剂进行甲苯 (T) 与甲醇 (M) 的择形甲基化反应。研究了金属改性对催化性能尤其是催化剂稳定性的影响。使用包括 X 射线衍射 (XRD)、扫描电子显微镜 (SEM) 和透射电子显微镜 (TEM) 在内的各种技术来表征催化剂。结果表明，SiO2含量为3wt%的P-Mg改性催化剂表现出优异的稳定性（大于500h），但降低了对二甲苯选择性（小于90%）。当进一步增加SiO2的量时，催化剂在相对较短的运行时间内失活，尽管对位选择性显着提高至99.5%。经过Pt、Pd、Co、Ni金属进一步改性的高对二甲苯选择性催化剂即使在运行100-400h后也表现出优异的稳定性，对二甲苯选择性超过98.3%，甲苯转化率为20.0%。因此，负载具有良好加氢性能的金属，如Pt、Pd、Co和Ni，是提高催化剂稳定性的有效方法。
Shape-selective methylation of toluene (T) with methanol (M) was carried out in a continuous flow fixed-bed reactor over modified HZSM-5 catalysts. The effect of metal modification on the catalytic performance, especially the catalyst stability, was investigated. Various techniques including X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM), were used to characterize the catalysts. The results showed that P–Mg modified catalysts with 3wt% SiO2exhibited excellent stability (more than 500h), but lowered p-xylene selectivity (less than 90%). Upon further increasing the amount of SiO2, the catalyst deactivated in a relatively short time on stream, although the para-selectivity was significantly increased up to 99.5%. The high p-xylene-selectivity catalyst modified further with Pt, Pd, Co, Ni metal demonstrated excellent stability, even after 100–400h on stream, and the selectivity for p-xylene of more than 98.3% with toluene conversion of 20.0% was achieved. Hence, loading metals with good hydrogenation properties, such as Pt, Pd, Co and Ni, was an effective method to improve the catalyst stability.