Monolithic metal-fiber@HZSM-5 core–shell catalysts for methanol-to-propylene

•We developed a monolithic metal-fiber@HZSM-5 core–shell catalyst.•Core–shell catalyst is obtained by growth of HZSM-5 on sinter-locked metal fibers.•Such catalyst offers dramatic selectivity and lifetime improvement in MTP reaction.•This approach propagates olefin methylation/cracking pathway in HP mechanism.

Monolithic metal-fiber@HZSM-5 core–shell catalysts have been developed by direct growth of zeolite crystals on a macroscopic 3D network of sinter-locked metal microfibers. This approach provides a combination of excellent thermal conductivity, hierarchical porous structure from micro- to macro-size, and unique form factor. The metal-fiber@HZSM-5 catalysts, with high HZSM-5 loadings (e.g., 27–30 wt%) and excellent core–shell robustness, deliver dramatic selectivity and life-time improvement in the methanol-to-olefin process. Such unprecedented performance is due to propagation of the olefin methylation/cracking cycle over the aromatic-based cycle in the methanol-to-hydrocarbon catalysis. Using a feed of 30 vol% methanol in N2, for example, at 480 °C high propylene selectivity of ∼46% can be obtainable with a total C2–C4 olefin selectivity of ∼70%, being much higher than that (∼37%, C2–C4 olefin selectivity of ∼64%) for the corresponding zeolite powder. The core–shell catalyst is stable at least for 210 h, almost 3-fold longer than the life-time of 60 h for the powdered HZSM-5 catalysts, because the coking rate is obviously suppressed in association with the propagated olefin-based cycle.

Graphical abstractMacroscopic metal-fiber@HZSM-5 core–shell catalysts are developed by direct growth HZSM-5 on 3D microfibrous substrates, demonstrating dramatic selectivity and stability improvement in the MTP application. The unprecedented performance is due to the promotion of olefin methylation/cracking cycle in the methanol-to-hydrocarbon catalysis.Figure optionsDownload full-size imageDownload as PowerPoint slide