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论文类型：期刊论文

发表时间：2010-10-25

发表刊物：ACS Fall Meeting on Renewable Alternatives to Petroleum and the Key Role of Catalysis

收录刊物：SCIE、EI、CPCI-S、Scopus

卷号：156

期号：1-2,SI

页面范围：69-73

ISSN号：0920-5861

关键字：Shape-selective methylation; p-Xylene; HZSM-5; Hydrogenation metal; Stability

摘要：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 3 wt% SiO(2) exhibited excellent stability (more than 500 h), but lowered p-xylene selectivity (less than 90%). Upon further increasing the amount of SiO(2), 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 100-400 h 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. (C) 2010 Elsevier B.V. All rights reserved.