Synthesis of mesoporous ZSM-5 zeolite encapsulated in an ultrathin protective shell of silicalite-1 for MTH conversion

Abstract

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Performance of mesoporous HZSM-5 and Silicalite-1 coated mesoporous HZSM-5 catalysts for deoxygenation of straw fast pyrolysis vapors

“…Shell-Meso-ZSM-5. Following previous work [50], the as-synthesized mesoporous ZSM-5 was impregnated first with TPAOH until incipient wetness in a Teflon beaker and dried overnight at room temperature and then with TEOS until incipient wetness and dried overnight at room temperature. The beaker was placed in a Teflon-lined stainless steel autoclave with distilled water around the beaker and heated at 180 °C for 72 h. The product was washed with distilled water and calcined at 550 °C for 20 h. The final product was ion exchanged (see Ion exchange section).…”

Seed-Assisted Synthesis of ZSM-5 Aggregates Assembled from Regularly Stacked Nanosheets and Their Performance in n-Hexane Aromatization

“…The sorption isotherms of both the S-1 series samples and the S-2 series samples were mainly type IV and a clear hysteresis loop in a P/P 0 range of 0.4−1.0 could be observed, indicating the existence of a hierarchical pore structure. 30,31 Especially, for samples S-1-1 and S-2-1, there was a steep nitrogen uptake at high relative pressure, implying the existence of a large size pore structure. 32 The specific surface area and external surface area of S-2-1 are 369 and 80 m 2 /g, respectively, larger than those of S-1-1 (Table 1).…”

Recent advances in hydrogenation of CO2 into hydrocarbons via methanol intermediate over heterogeneous catalysts

“…The position of coke could be on the internal surface of the micropores (called soft/internal coke) blocking the accessibility to the active sites or as a coating on the outer surface of the zeolite crystal (called external coke) blocking the entrance to the internal pores. 190,191 The growth of coke species inside the internal pore is limited by the size and shape of the pore. No such spatial limitation is anticipated for the external coke.…”

“…Acid sites on the external surface of the zeolites deactivate more quickly than those located inside the crystals due to a lack of shape selectivity. Therefore, to improve the catalyst lifetime, Goodarzi et al 191 attempted a surface passivation technique involving the introduction of an inert porous shell of silicalite-1 with a thickness of 15 nm on the surface of a mesoporous ZSM-5 catalyst, thus replicating a core-shell structure. In comparison to the mesoporous ZSM-5 without the protective shell, the one with the protective shell had 10 times longer catalyst lifetime extending up to 70 hours of reaction as compared to 7 hours, and 12 times higher conversion capacity based on the acid sites (from 27 to 63%).…”