水热处理对纳米HZSM-5分子筛催化甲醇制汽油性能的影响

对比了微米HZSM-5和纳米HZSM-5分子筛催化甲醇制汽油(MTG)反应的性能，发现采用纳米HZSM-5分子筛催化剂能得到较高的汽油收率和较长的使用寿命。对纳米HZSM-5分子筛在不同温度下进行水热处理，利用低温N₂吸附-脱附、XRD、NH_3-TPD手段对水热处理前后的分子筛样品进行表征。在380℃、1.0 MPa、空速3.0 h^-1的反应条件下进行MTG反应，对水热处理后的催化剂进行评价。结果表明，对纳米HZSM-5水热处理能显著提高其催化MTG反应的汽油收率和延长催化剂使用寿命。纳米HZSM-5分子筛的最佳水热处理温度为600℃，在此条件下处理后用于MTG反应，催化剂的使用寿命由水热处理前的84 h显著增加到216 h，积炭量却由35.8%降至23.7%。另外，随着纳米HZSM-5催化剂水热处理温度的升高，其催化MTG所得汽油产品中的异构烷烃和烯烃含量增加，芳烃含量降低。

Effect of Hydrothermal Treatment on Catalytic Performance of Nanosize HZSM-5 Zeolites for Methanol Conversion to Gasoline

The catalytic performances of microsize and nanosize HZSM-5 zeolites for the conversion of methanol to gasoline (MTG) were compared. The results showed that with nanosize HZSM-5zeolite as catalyst, a higher gasoline yield of MTG and longer catalyst lifetime could be obtained. Hydrothermal method was used to treat the nanosize HZSM-5 zeolite, and the parent and hydrothermal treated samples were characterized by N₂ adsorption-desorption, XRD and NH₃-TPD. Their performances for MTG were tested at reaction temperature of 380℃, pressure of 1.0 MPa and methanol mass space velocity (MHSV) of 3.0 h^-1. It is found that the gasoline yield of MTG and catalytic lifetime of the treated nanosize HZSM-5were significantly increased. When the nanosize HZSM-5zeolite was hydrothermal treated at the optimum temperature of 600℃, the catalytic lifetime was increased from 84 h to 216 h, and the content of carbon deposition on the deactivated catalyst was decreased from 35.8% to 23.7%, compared to its parent catalyst. In addition, isomerization alkane and olefin content in gasoline product of MTG increased with the increase of hydrothermal treatment temperature of the catalyst, while the aromatic content decreased.