Designing organic structure-directing agent for cost-effective production of multipore MSE zeolite

Abstract

Multipore MSE zeolite possesses three-dimensional (3D) pore-network constructed of interconnected 10- and 12- membered rings (MRs), i.e., between its broadly used cousins, medium-pore MFI and large-pore Beta, and has exhibited promising catalytic performances in catalytic cracking reactions. One major bottleneck for the commercial deployment of MSE zeolite is the prohibitive production cost due to the use of expensive organic structure directing agent (OSDA). We report here a designed inexpensive OSDA, dispiro[piperidine-1,2′-(1′,2′,3′,5′,6′,7′-hexahydrobenzo [1,2-c: 4, 5-c′] dipyrrolium)-6′,1″-piperidine, that can better stabilize the framework and is specific to the generation of MSE in the presence of K⁺. The OSDA is occluded in the supercage and 12-MR straight channel, while the K⁺ occupies the 6²5⁴4² cage, affording high crystallinity and strong acidity. The dealuminated zeolite shows improved light olefin (in particular, propylene) selectivity and catalyst lifetime in catalytic cracking of typical naphtha pool molecule n-heptane. The recipe is a step forward for the specific, low-cost generation of the MSE zeolite and may inspire more investigations on its catalytic applications.