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Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization.

Shi CW, Wu WY, Li S, Bian X, Zhao SL, Pei MY - Sci Rep (2016)

Bottom Line: The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane.The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization.The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves.

View Article: PubMed Central - PubMed

Affiliation: College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning Shihua University, Funshun Liaoning 113001, China.

ABSTRACT
Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves.

No MeSH data available.


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Aromatization performance of the two composite molecular sieve samples.
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f9: Aromatization performance of the two composite molecular sieve samples.

Mentions: The results of n-pentane aromatization reactions catalyzed by different composite molecular sieves are shown in Fig. 9. As seen in Fig. 9, when composite zeolite Y/S-S (via single crystallization) was used as the catalyst, the yields of benzene and toluene were higher compared to using core-shell composite Y/S-D (via secondary crystallization). However, Y/S-D offered higher yield of xylenes, which have higher application value. In addition, the conversion obtained by using Y/S-D was 96.6% which was higher than those obtained by using Y/S-S (94.7%). This might be because the SBA-15 mesoporous phase of Y/S-D is uniformly distributed on the outer surface of the Y core. As a result, there is a relatively strong acid environment (provided by the microporous molecular sieve Y) suitable for aromatization reaction, as well as ordered and connected channels with a relatively large mesoporous space structure (provided by mesoporous molecular sieve SBA-15). The latter property favors the entrance of the sterically hindered n-pentane molecules, and facilitates shape selectivity and the exit of large products such as benzene, toluene and xylenes. Thus, the composite molecular sieve prepared by secondary crystallization provided more appropriate acidity and more regular mesoporous channel structure, resulting in better catalytic performance in the aromatization reaction.


Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization.

Shi CW, Wu WY, Li S, Bian X, Zhao SL, Pei MY - Sci Rep (2016)

Aromatization performance of the two composite molecular sieve samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4814903&req=5

f9: Aromatization performance of the two composite molecular sieve samples.
Mentions: The results of n-pentane aromatization reactions catalyzed by different composite molecular sieves are shown in Fig. 9. As seen in Fig. 9, when composite zeolite Y/S-S (via single crystallization) was used as the catalyst, the yields of benzene and toluene were higher compared to using core-shell composite Y/S-D (via secondary crystallization). However, Y/S-D offered higher yield of xylenes, which have higher application value. In addition, the conversion obtained by using Y/S-D was 96.6% which was higher than those obtained by using Y/S-S (94.7%). This might be because the SBA-15 mesoporous phase of Y/S-D is uniformly distributed on the outer surface of the Y core. As a result, there is a relatively strong acid environment (provided by the microporous molecular sieve Y) suitable for aromatization reaction, as well as ordered and connected channels with a relatively large mesoporous space structure (provided by mesoporous molecular sieve SBA-15). The latter property favors the entrance of the sterically hindered n-pentane molecules, and facilitates shape selectivity and the exit of large products such as benzene, toluene and xylenes. Thus, the composite molecular sieve prepared by secondary crystallization provided more appropriate acidity and more regular mesoporous channel structure, resulting in better catalytic performance in the aromatization reaction.

Bottom Line: The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane.The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization.The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves.

View Article: PubMed Central - PubMed

Affiliation: College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning Shihua University, Funshun Liaoning 113001, China.

ABSTRACT
Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves.

No MeSH data available.


Related in: MedlinePlus