The synthesis of endurable B–Al–ZSM-5 catalysts with tunable acidity for methanol to propylene reaction

A series of boron isomorphously framework-substituted ZSM-5 (Bx–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 1.8 h− 1 (700 h for B1–Al–ZSM-5 and 100 h for ZSM-5, respectively). The enhancement of catalytic stability can be attributed to the increase of weak acid sites on the ZSM-5 catalysts.

Conversion of methanol (a) and selectivity of propylene (b) over zeolites B0–Al–ZSM-5 (□), B0.5–Al–ZSM-5 (■), B1–Al–ZSM-5 (▽), B2–Al–ZSM-5 (▼). Reaction conditions: WHSV = 1.8 h−1, T = 460 °C, n (CH3OH) : n (H2O) = 1 : 3, Ptotal = 1 atm.Figure optionsDownload as PowerPoint slideHighlights
► ZSM-5 zeolite catalysts with tunable acidity are synthesized.
► Weak acid amount is adjusted whereas strong acid amount keeps constant.
► Acidity is tuned to improve catalytic stability and product selectivity.
► Catalytic stability is remarkably enhanced after B incorporation in MTP reaction.