Search

A series of ZSM-5 zeolites with tunable mesoporosity were synthesized by a facile ultrasound-assisted method. XRD, FT-IR and NH 3 -TPD results exhibited that as-synthesized ZSM-5 kept the MFI structure as well as the original acidity. Traced by TEM techniques, the crystallization process, especially the state of initial amorphous gel, was found notably affected by the ultrasound treatment by breaking the weak bonds, which led to formation of mesopores in crystals. The ZSM-5 catalysts with abundant mesoprores inhibited coking significantly and showed high catalytic stability for methanol to propylene reaction. The Z5-us-60 catalyst exhibited the highest catalytic stability for >600 h at a high WHSV of 4.0 h −1 . [ABSTRACT FROM AUTHOR]

Abstract: A series of boron isomorphously framework-substituted ZSM-5 (B x –Al–ZSM-5, Si/Al=200, B/Al=X) were synthesized and used to selectively transform methanol to propylene (MTP). The catalytic stability can be significantly influenced by B incorporation. In comparison with the conventional ZSM-5, the B1–Al–ZSM-5 catalyst afforded a 7-time-long catalytic life under a space velocity of WHSV 1.8h−1 (700h for B1–Al–ZSM-5 and 100h for ZSM-5, respectively). The enhancement of catalytic stability can be attributed to the increase of weak acid sites on the ZSM-5 catalysts. [Copyright &y& Elsevier]

Abstract: Modified high silica HZSM-5 catalysts have been used to selectively transform methanol to propylene (MTP). The HZSM-5 catalyst with a Si/Al ratio of 220 exhibited satisfying catalytic performance (space time yield of propylene is up to 18mmol/gh). The selectivity of propylene can be obviously affected by additives. P leads to a pronounced improvement of propylene selectivity up to 55.6% with complete conversion of methanol. The enhancement of propylene selectivity and catalytic life can be attributed to partial elimination of the strong acid sites on the HZSM-5 catalyst. [Copyright &y& Elsevier]