Elucidating the promoting advantages and fundamentals for their creation in Sn-modified commercial CrOx/Al2O3 catalyst for propane dehydrogenation

Zhang, Lei; Chen, Kezhen; Chen, Huarong; Han, Xiangyun; Liu, Chenqian; Qiao, Lingdan; Wu, Wenwei; Yang, Bairen

doi:10.1016/j.cej.2024.149366

Cited by 4 publications

(1 citation statement)

References 51 publications

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“…For example, taking advantage of the large surface area and ordered pore structure of ZSM-5, with the pore size of 0.56 × 0.51 nm being larger than the molecule dynamics diameter (0.47 nm) of propane molecules, Wang et al [18] investigated propane dehydrogenation over Cr loaded ZSM-5 (Cr-ZSM-5) zeolite, the Brönsted acid sites of which have also been reported to be favorable for the adsorption and reaction of propane. Igonina et al [19] impregnated 5 wt.% Cr on MCM-41 using the first impregnation method, which resulted in 20% conversion of C 3 H 8 and 76% selectivity of C 3 H 6 at 650 • C. Singh et al [20] used ZrO 2 as a support loaded with 2.5 wt.% Cr and achieved 16% conversion of C 3 H 8 and 86.6% selectivity of C 3 H 6 at 550 • C. Zhang et al [21] introduced 5 wt.% Sn into an Al 2 O 3 catalyst loaded with 3 wt.% Cr in order to improve the stability of the catalyst. The initial conversion of C 3 H 8 in the catalyst was 40%, and after 10 h of reaction, the conversion of C 3 H 8 was stable at 32%.…”

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confidence: 99%

CO2 Oxidative Dehydrogenation of Propane to Olefin over Cr-M (M = Zr, La, Fe) Based Zeolite Catalyst

Xing,

Liu,

Dai

et al. 2024

Catalysts

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CO2 oxidative dehydrogenation of propane (CO2-ODHP), being not only favorable for olefin production but also beneficial for CO2 emission control, has recently attracted great attention. Here, a series of single metal (Cr) and bimetal (Zr, La, Fe) modified ZSM-5 zeolites were prepared via an impregnation method. It was found that the bimetal modified ZSM-5 possessed much higher C3H8 and CO2 conversion than that of monometallic modified Cr3%-ZSM-5 (Cr3%-Z5), especially for Cr3%Zr2%-ZSM-5 (Cr3%Zr2%-Z5), which displayed the highest activity (65.4%) and olefin yield (1.65 × 103 μmol·gcat−1 h−1). Various characterizations were performed, including XRD, N2 adsorption-desorption, H2-TPR, Raman, XPS, HAAD-STEM, and TEM. It was revealed that Zr not only favored an improvement in the redox ability of Cr, but also contributed to the surface dispersion of loaded Cr species, constituting two major reasons explaining the superior activity of Cr3%Zr2%-Z5. To further improve CO2-ODHP catalytic behavior, a series of Cr3%-ZSM-5@SBA-15-n composite zeolite catalysts with diverse (ZSM-5/SBA-15) mass ratios were prepared (Cr3%-ZS-n, n = 0.5, 2, 6, 16), which screened out an optimum mass ratio of six. Based on this, the Cr3%Zr2%-ZS-6 compound was further prepared, and it eventually achieved even higher CO2-ODHP activity (76.9%) and olefin yield (1.72 × 103 μmol·gcat−1 h−1). Finally, the CO2-ODHP reaction mechanism was further investigated using in situ FTIR, and it was found that the reaction followed the Mars–van Krevelen mechanism, wherein CO2 participated in the reaction through generation of polydentate carbonates. The Cr6+ constituted as the active site, which was reduced to Cr3+ after the dihydrogen reaction, and was then further oxidized into Cr6+ by CO2, forming polydentate carbonates, and thus cycling the reactive species Cr6+. Additionally, assisted by a Brönsted acid site (favoring breaking of the C-C bond), C2H4 and CH4 were produced.

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