Research PaperVapor-phase transport (VPT) modification of ZSM-5/SiC foam catalyst using TPAOH vapor to improve the methanol-to-propylene (MTP) reaction

•TPAOH VPT modification of structured ZSM-5/SiC foam catalysts.•Effective conversion of aluminosilicate binder to zeolitic phase by TPAOH vapor.•Enhanced catalytic performance of VPT modified ZSM-5/SiC foam catalyst in MTP reaction.•Intrinsic properties of SiC foam are beneficial to MTP process.

Tetrapropylammonium hydroxide (TPAOH) was introduced in the vapor phase to perform the vapor-phase transport (VPT) modification of the structured ZSM-5 supported on SiC foam (ZSM-5/SiC foam) catalyst. An optimum precursor concentration of 0.5 M TPAOH could effectively convert the amorphous aluminosilicate binder to the zeolitic phase with improved intracrystal mesopores, nanosized crystals (ca. 100 nm), high concentration of acidity sites (83 mmol g−1) as well as a high value of the relative acidity (0.7). Combined with the intrinsic property of macroscopic SiC foams such as the low pressure drop and the high thermal conductivity (14 W m−1 K−1 at 773 K), TPAOH VPT modified ZSM-5/SiC foam catalyst demonstrated an excellent activity in the catalytic methanol-to-propylene (MTP) reaction, surpassing the state-of-the-art hierarchal ZSM-5 monolith catalyst. The catalyst showed an extended activity for ca. 970 h (>95% methanol conversion) with the high selectivity to the propylene (>45%). The coke formation was significantly retarded (ca. 2.1 × 10−2 wt.% h−1) due to the enhanced transport phenomena within the developed structured catalyst.

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