Fe-Substituted Pt/HZSM-48 for Superior Selectivity of i-C12 in n-Dodecane Hydroisomerization

Shang, Shujie; Li, Wenhui; Zhou, Ajuan; Zhang, Jiaxing; Yang, Hong; Zhang, Anfeng; Guo, Xinwen

doi:10.1021/acs.iecr.1c04091

Cited by 19 publications

(10 citation statements)

References 38 publications

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“…The pyridine adsorption spectra (Figure 2d) exhibit two IR bands located at 1546 and 1450 cm −1 , which are assigned to pyridine adsorbed on the Brønsted and Lewis acid sites, respectively. 33,34 The majority of the acid sites are Brønsted acid, suggesting that most of the aluminum species are incorporated in the zeolite framework, consistent with the 27 Al MAS NMR results (Figure S1). There is only one resonance signal at 55 ppm, indicating that the aluminum atoms are in the form of the tetrahedral coordination framework Al.…”

Section: Resultssupporting

confidence: 82%

“…The minor differences between the ZSM-5 nanosheets with different b -axis thicknesses suggest that the strength and concentration of acid sites are nearly identical due to their similar Si/Al ratios (Table ). The pyridine adsorption spectra (Figure d) exhibit two IR bands located at 1546 and 1450 cm –1 , which are assigned to pyridine adsorbed on the Brønsted and Lewis acid sites, respectively. , The majority of the acid sites are Brønsted acid, suggesting that most of the aluminum species are incorporated in the zeolite framework, consistent with the 27 Al MAS NMR results (Figure S1). There is only one resonance signal at 55 ppm, indicating that the aluminum atoms are in the form of the tetrahedral coordination framework Al. , A similar concentration of Brønsted acid sites in all samples (Table ) facilitate unraveling the thickness effect on the alkylation reaction.…”

Section: Resultssupporting

confidence: 79%

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b-Axis-Oriented ZSM-5 Nanosheets for Efficient Alkylation of Benzene with Methanol: Synergy of Acid Sites and Diffusion

et al. 2023

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ZSM-5 nanosheets are promising catalysts for the catalytic reactions controlled by diffusion limitations. This study reveals its significant application in the alkylation of benzene with methanol. The b-axis-oriented ZSM-5 nanosheets with similar acid property but varied thicknesses of about 30, 90, and 300 nm were prepared to investigate the effect of thickness on their catalytic properties for alkylation reactions. Comparative results demonstrate that the sample with a thickness of 30 nm exhibits higher benzene conversion, xylene selectivity, and methyl selectivity (up to 97%), accompanied by an ultralong lifetime (up to 1000 h, 10 times longer than that of the sample with a thickness of 300 nm) and lower byproduct ethylbenzene selectivity. This is ascribed to the shortened straight channel length, increased specific surface area, and enlarged mesopore volume that significantly facilitate the diffusion of reactants and products, increase the accessibility of acid sites, and decrease the coke formation. Moreover, compared with conventional ZSM-5 nanocrystals, ZSM-5 nanosheets deliver a substantially extended lifetime due to fewer framework defects. Most significantly, this study unravels the diffusion effect on ethylbenzene selectivity over ZSM-5 nanosheets with different thicknesses and illustrates the role of strong Brønsted acid sites in the dynamic changes of ethylbenzene selectivity. In light of the above analysis, we developed a precoking strategy and an introducing-heteroatom strategy to precisely tailor the catalyst acidity, further suppressing the ethylbenzene formation (<0.3%) while maintaining long-term stable operation (>300 h).

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Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 79%

b-Axis-Oriented ZSM-5 Nanosheets for Efficient Alkylation of Benzene with Methanol: Synergy of Acid Sites and Diffusion

et al. 2023

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“…NH 3 -TPD and Py-IR tests were performed to investigate the acidity of the four samples. As seen in Figure a, all samples display two NH 3 desorption peaks attributed to the weak acid sites and strong acid sites . By integration of the area of the entire NH 3 desorption peak on the NH 3 -TPD curve, the total acidity can be obtained.…”

Section: Resultsmentioning

confidence: 97%

Tuning Pt Location and Intimacy between Pt–Acid Active Sites in Pt/ZSM-5 Bifunctional Catalysts for Effective Alkylation of Benzene with Ethane

Zhou,

Zhang,

Shang

et al. 2024

Ind. Eng. Chem. Res.

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The rational design of bifunctional catalysts is an effective strategy for improving the reaction performance. In this work, three Pt/ZSM-5 catalysts (all of the loading of platinum is relatively low, about 0.2 wt %) were prepared through three different preparation methods, and then their application in the alkylation of benzene with ethane to ethylbenzene was studied. Among the three catalysts, the one prepared by the in situ encapsulation method contains nanoparticles of Pt mainly located in the interior of ZSM-5, and there is a low intimacy between the Pt−acid sites on the support. This catalyst shows the lowest benzene conversion. On the other hand, for the catalyst prepared by the impregnation method, the platinum particles are mainly located on the external surfaces of ZSM-5, and there is high intimacy between the Pt−acid active sites. This catalyst delivers high benzene conversion but low ethylbenzene selectivity due to easy access to the Pt−acid active sites for the side reactions. The best catalytic activity with a 90.6% ethylbenzene selectivity and a benzene conversion of 9.8% is achieved by the catalyst produced by ion exchange. This catalyst contains Pt located on both the external and interior of ZSM-5, with the highest intimacy between the Pt− acid active sites. It achieves not only high benzene conversion but also high ethylbenzene selectivity. This study reveals the relationship between the location and intimacy between two active sites of Pt/ZSM-5 catalysts in alkylation reactions and demonstrates a great significance for the rational design of other bifunctional or multifunctional metal−zeolite catalysts.

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“…The ZSM-48 seed parent was synthesized by a hydrothermal process described in the literature. 32 Aluminum sulfate was used in synthesis as the aluminum source, and the molar composition of 1.0 SiO 2 :0.1 NaOH:0.005 Al(OH) 3 :0.03 HMBr 2 :50 H 2 O was explored and crystallized at 190 °C for 120 h. Then the solid was recovered by centrifugation at 4000 rpm and washed with distilled water. Finally, the solid product was dried in an oven at 80 °C in air.…”

Section: Materials and Synthesismentioning

confidence: 99%

Ultrafast Synthesis and Regulating Al Status of Mesoporous ZSM-48 Zeolite via a Pretreated-Seed-Solution-Assisted Strategy

Shang

Ren

Liu

et al. 2023

Crystal Growth & Design

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Ultrafast synthesis of nanocrystal assembled mesoporous ZSM-48 zeolite spheres of highly crystalline was achieved within 1.5 h by using pretreated-seed-solution-assisted strategy. Interestingly, by altering the introducing sequence of aluminum source (in the pretreated seed solution or in the synthesis gel), the obtained ZSM-48 with similar particle size and total acid sites exhibited quite different crystallization behavior and acid property in terms of Al distribution and acid strength, because of the distinct local microenvironment (Al-rich or Al-free) in the pretreated seed solution. The HZ48-Al-pre (introduce an Al source to the pretreated seed solution) had more framework Al(IV) content and stronger acid strength than that of the HZ48-Al-post (synthesized by the Al-free pretreated seed solution). The corresponding Pt supported catalysts showed a great difference in the n-C 12 hydroisomerization reation. The Pt/HZ48-Al-pre catalyst had a very low selectivity (41.1%), and the maximum iso-yield was only 35.5%. However, the ultrafast synthesizedPt/HZ48-Al-post-1.5h catalyst exhibited a superior selectivity (90.1%) with a total i-C 12 yield of 82.3% at 330 °C, which was a high level in the exist literature reports.

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Fe-Substituted Pt/HZSM-48 for Superior Selectivity of i-C₁₂ in n-Dodecane Hydroisomerization

Cited by 19 publications

References 38 publications

b-Axis-Oriented ZSM-5 Nanosheets for Efficient Alkylation of Benzene with Methanol: Synergy of Acid Sites and Diffusion

b-Axis-Oriented ZSM-5 Nanosheets for Efficient Alkylation of Benzene with Methanol: Synergy of Acid Sites and Diffusion

Tuning Pt Location and Intimacy between Pt–Acid Active Sites in Pt/ZSM-5 Bifunctional Catalysts for Effective Alkylation of Benzene with Ethane

Ultrafast Synthesis and Regulating Al Status of Mesoporous ZSM-48 Zeolite via a Pretreated-Seed-Solution-Assisted Strategy

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