Citric-acid-induced mesoporous SAPO-11 loaded with highly dispersed nickel for enhanced hydroisomerization of oleic acid to iso-alkanes

In this study, a series of Ni/SAPO-11 catalysts with different Ni loadings were prepared by citric acid-assisted impregnation for the hydroisomerization of oleic acid to iso-alkanes. Serving as a chelating ligand, citric acid first promoted the dispersion of Ni nanoparticles loaded on SAPO-11. Becau...

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Bibliographic Details
Published in:Fuel processing technology 2019-05, Vol.187, p.52-62
Main Authors: Yang, Lingmei, Xing, Shiyou, Sun, Hongzhe, Miao, Changlin, Li, Ming, Lv, Pengmei, Wang, Zhongming, Yuan, Zhenhong
Format: Article
Language:English
Subjects:
Acids
Alkanes
Aluminum oxide
Catalysis
Catalysts
Chelation
Citric acid
Dispersion
Highly dispersed Ni
Hydroisomerization
Isomerization
Lewis acid
Mesoporous SAPO-11
Nanoparticles
Nickel
Oleic acid
Selectivity
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Summary:In this study, a series of Ni/SAPO-11 catalysts with different Ni loadings were prepared by citric acid-assisted impregnation for the hydroisomerization of oleic acid to iso-alkanes. Serving as a chelating ligand, citric acid first promoted the dispersion of Ni nanoparticles loaded on SAPO-11. Because of its acid properties, citric acid facilitated the removal of aluminium oxide species, contributing to the formation of a mesoporous SAPO-11 structure. A maximum of 67.3 mol% of iso-alkanes was formed using 7Ni/SAPO-11 as a catalyst under optimal conditions of 360 °C, 4 h, and 4.0 MPa H2. After reusing for five cycles, the catalyst still exhibited 21.5 mol% isomer selectivity. The reaction pathways and catalytic mechanisms concerning the oleic acid hydroisomerization process were proposed and discussed. The hydroisomerization of oleic acid mainly depended on the catalyst's Lewis acid sites, with the assistance of the metal centre and Brönsted acid sites. The mesoporous structure of SAPO-11 facilitated the availability of a significant number of catalytic Lewis acid sites, which, together with the highly dispersed Ni centres, contributed to the enhanced product isomerization. [Display omitted] •Ni/SAPO-11 catalysts were prepared with the assistance of citric acid.•Citric acid induced the formation of highly dispersed Ni and mesoporous SAPO-11.•High isomer selectivity (67.3 mol%) was achieved with 7 wt% Ni loading.•Lewis acid sites on the catalyst controlled the hydroisomerization of oleic acid.
ISSN:0378-3820
1873-7188
DOI:10.1016/j.fuproc.2019.01.008