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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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XRD spectra of Y/SBA-15 at different crystallization times (a) SWXD and (b) WXRD.
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f1: XRD spectra of Y/SBA-15 at different crystallization times (a) SWXD and (b) WXRD.

Mentions: Figure 1 shows the XRD spectra of Y/SBA-15 composite molecular sieves prepared at 100 °C for different crystallization times. It can be seen from Fig. 1 that when the crystallization time was 10 hours, there was no mesoporous characteristic diffraction peak at 100, 110, or 200 in Fig. 1(a). Also, the intensities of the Y zeolite characteristic peaks at 111, 533, and 751 stayed constant in Fig. 1(b). Clearly, the desired reaction did not proceed at this short crystallization time, as the SBA-15 was still at the amorphous gel stage. When the crystallization time was extended to 24 hours, a weak mesoporous characteristic peak started to show up at 100 degrees. However, there was no characteristic peak at 110 or 200, indicating that formation of the mesoporous phase was incomplete. When the crystallization time was extended to 36 hours, the mesoporous characteristic peak gradually increased and the characteristic peak of SBA-15 appeared in the wide angle area along with the characteristic peak of Y, which indicated good degree of crystallization for both mesopores and micropores. When the crystallization time was extended to 48 hours, the characteristic peak intensities decreased slightly, perhaps indicating some degradation. Thus, the crystallization time of 36 hours is considered optimum for the SBA-15 to form a mesoporous phase with good crystallization degree on the surface of the microporous phase Y.


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)

XRD spectra of Y/SBA-15 at different crystallization times (a) SWXD and (b) WXRD.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: XRD spectra of Y/SBA-15 at different crystallization times (a) SWXD and (b) WXRD.
Mentions: Figure 1 shows the XRD spectra of Y/SBA-15 composite molecular sieves prepared at 100 °C for different crystallization times. It can be seen from Fig. 1 that when the crystallization time was 10 hours, there was no mesoporous characteristic diffraction peak at 100, 110, or 200 in Fig. 1(a). Also, the intensities of the Y zeolite characteristic peaks at 111, 533, and 751 stayed constant in Fig. 1(b). Clearly, the desired reaction did not proceed at this short crystallization time, as the SBA-15 was still at the amorphous gel stage. When the crystallization time was extended to 24 hours, a weak mesoporous characteristic peak started to show up at 100 degrees. However, there was no characteristic peak at 110 or 200, indicating that formation of the mesoporous phase was incomplete. When the crystallization time was extended to 36 hours, the mesoporous characteristic peak gradually increased and the characteristic peak of SBA-15 appeared in the wide angle area along with the characteristic peak of Y, which indicated good degree of crystallization for both mesopores and micropores. When the crystallization time was extended to 48 hours, the characteristic peak intensities decreased slightly, perhaps indicating some degradation. Thus, the crystallization time of 36 hours is considered optimum for the SBA-15 to form a mesoporous phase with good crystallization degree on the surface of the microporous phase Y.

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