Catalytic performance of La-modified HZSM-5 catalysts for methanol to gasoline reaction
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摘要: 采用浸渍法制备了La改性HZSM-5分子筛催化剂,利用X射线衍射(XRD)、氮气吸附-脱附、氨气程序升温脱附(NH3-TPD)以及吡啶吸附红外光谱(Py-FTIR)技术对催化剂进行表征,并在固定床微型反应评价装置上,在反应温度350℃,系统压力0.1 MPa,甲醇质量空速4.74 h-1的条件下,考察La改性HZSM-5分子筛催化剂的甲醇转化制汽油反应性能。结果表明,La改性HZSM-5分子筛催化剂的酸量降低,比表面积和孔容减小。La负载量为4%时,其MTG反应性能最佳,催化剂的寿命和汽油收率分别由改性前的12 h和52.69%增加到16 h和59.28%。此外,随着La负载量的增加,汽油中芳烃含量显著降低,降幅达18%。Abstract: La-modified HZSM-5 catalysts were prepared by impregnation method, and characterized by XRD, NH3-TPD, Py-FTIR and N2 adsorption/desorption techniques. Their catalytic performance in methanol to gasoline (MTG) reaction was evaluated in a fixed-bed tubular reactor at 350℃ and WHSV of 4.74 h-1 under ambient pressure. The results show that the introduction of La decreased the amount of acid sites, specific surface area and pore volume of HZSM-5 catalyst. The catalyst with La loading of 4% exhibited the best catalytic performance in MTG reaction, over which the lifetime and gasoline yield increased from 12 h and 52.69% to 16 h and 59.28%, respectively. In addition, the selectivity to aromatics in gasoline decreased markedly by 18% with increasing La content.
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Key words:
- methanol to gasoline /
- HZSM-5 zeolite /
- La
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表 1 不同La负载量HZSM-5催化剂的结构性质和酸性质
Table 1 Textural properties and acid properties of HZSM-5 catalysts with different La contents
Catalyst ABET/(m2·g-1) Amicro/(m2·g-1) vtotal/(cm3·g-1) vmicro/(cm3·g-1) L/B HZ5-0 372.5 350.1 0.23 0.15 0.450 HZ5-1 343.4 331.3 0.21 0.13 0.483 HZ5-2 341.6 323.6 0.20 0.12 0.528 HZ5-4 338.2 311.5 0.19 0.12 0.574 HZ5-6 331.1 308.9 0.19 0.11 0.755 -
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