Influence of boron promotion on the physico-chemical properties and catalytic behavior of Zn/ZSM-5 in the aromatization of n-hexane

Abstract

The characterization and catalytic performance of Zn/ZSM-5 and Zn-B/ZSM-5 catalysts in the n-hexane aromatization was reported. Catalysts were prepared by post-synthesis impregnation and thoroughly characterized by means of XRD, Py-FTIR, N2 adsorption, 27 Al and 11 B MAS NMR spectroscopy and electron microscopy techniques. The incorporation of zinc reduces the Brønsted acid site density and increases the Lewis acidic sites of the final ZSM-5 based catalysts. The presence of boron slightly reduces the initial activity of the catalyst but slows down its deactivation rate.

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).…”

“…Both the conversion of n-hexane and the selectivity of BTEX were in the range of papers working under similar reaction conditions. 30,37 The main products were methane, C 2 −C 4 olefins, and BTEX (Table 3). Selectivity toward saturated counterparts was lower than the selectivity of alkenes through the reaction, indicating that the hydrogen transfer to the olefins was not the main route.…”

A Comparative Study of Aromatization Catalysts: The Advantage of Hybrid Oxy/Carbides and Platinum-Catalysts Based on Carbon Gels

“…The highest aromatization selectivity was observed for Zn/ZSM5 (around 43%) while Mo/ZSM5 exhibits the lowest selectivity values (between 20 and 25%), even worse than those observed for acid forms. More recently, Huyen [31] et al prepared Zn/ZSM-5 and B-Zn/ZSM5 catalysts. Zn/ZSM5 is more active and selective to benzene, but deactivated faster.…”

Synthesis and Characterization of LSX Zeolite/AC Composite from Elutrilithe

“…The Si/Al molar ratios in the samples were determined by XRD [17,18] using the Breck and Flanigen equation: ((192 × 0.00868)/(a 0 -24.191))-1, in which a 0 is the lattice parameter calculated by XRD. The crystallinities of the samples were determined from the intensity of the XRD characteristic peaks [19,20], and the values were compared to those of commercial X-zeolite and A-zeolite (purchased from China Petroleum and Chemical Co. Ltd, Liaoning, China), which were considered as having 100% crystallinity. The crystallinities of FAU and LTA in the samples were denoted as Xx and Xa, respectively.…”