Formation and Function of Formate in the Side-Chain Alkylation of Toluene with Methanol

Lin, Dan; Zhao, Huimin; Zhang, Xiaoyue; Lan, Dongxue; Yuan, Chun

doi:10.3724/sp.j.1088.2012.11243

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…To further understand the reaction mechanism, in situ DRIFTs are performed for CH 3 OH dehydrogenation on CsX-P and CsX-BN-600 catalysts (Figure ). After introducing CH 3 OH for reaction over CsX-BN-600, the characteristic peaks ascribed to the formates (HCOO*) at 2825 and 2887 cm –1 are gradually detected observed (Figure a). , Meanwhile, the peaks at around 2931 cm –1 assigned to the methoxy species (H 3 CO*) are simultaneously observed. , Such phenomena confirm that formates and methoxy are crucial intermediates for styrene production during the side-chain alkylation process, in line with the previous reports. − In comparison with CsX-BN-600, CsX-P also shows the characteristic peaks of the above crucial intermediates, but in a much lower intensity (Figure b), corresponding to its poorer catalytic performance in the toluene side-chain alkylation. Therefore, we infer that the formation of more active intermediates (HCOO* and H 3 CO*) is another reason responsible for the superiority of the catalyst fabricated via isomorphous N doping.…”

Section: Resultssupporting

confidence: 87%

Restructuring Surface Lewis Pairs of FAU Zeolite through N Doping for Boosting the Toluene Side-Chain Alkylation Performance

Hong,

Wang,

Fang

et al. 2024

Inorg. Chem.

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Toluene side-chain alkylation with methanol for the styrene monomer formation remains a great challenge. An optimal synergy between acidic and basic sites on zeolites is required for an efficient catalysis process. It is important to modulate the surface Lewis acid−base pairs precisely. Herein, we report a strategy to restructure the surface Lewis acid−base pairs in cesiummodified X zeolite (CsX) by N doping. In the process of toluene side-chain alkylation, the CsX-BN-600 catalyst, where N species is doped into the framework of the X zeolite, exhibits 2.7 times the styrene formation rate and a much better selectivity of 85.7% in comparison to the parent CsX of 70.1% selectivity to styrene at the same reaction conditions. The introduction of N species into zeolites acts as a new Lewis base site and optimizes the Lewis sites due to its ability of electron donation. Meanwhile, the frustrated Lewis pair (FLP) between the deprotonated framework nitrogen in X zeolite and positively polarized C species in the side-chain alkylation reaction is created. Furthermore, the N doping contributes to the generation of the active intermediates of HCOO* and H 3 CO*. These reasons favor the superiority of the catalyst through N doping.

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Section: Resultssupporting

confidence: 87%

Restructuring Surface Lewis Pairs of FAU Zeolite through N Doping for Boosting the Toluene Side-Chain Alkylation Performance

Hong,

Wang,

Fang

et al. 2024

Inorg. Chem.

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“…Additionally, the acid and alkali centers must be in close proximity on the surface and pores of the zeolite. This proximity facilitates contact between the generated alkylating reagent and activated toluene, thereby enabling side chain alkylation reactions [28]. Early works also suggested that the presence of a high density of basic sites in the CsX catalyst is related to the transformation of unidentate formate into bidentate formate, an unfavorable intermediate that can be easily transferred to CO and H 2 , thus decreasing the utilization of methanol and side chain product yield [32].…”

Section: Discussionmentioning

confidence: 99%

“…The nature of the active center of the catalyst and its role in the side chain alkylation reaction of toluene have been extensively studied [21,[26][27][28]. The alkylation of toluene and methanol proceeds smoothly through the synergistic effect of the acid-base center [29,30].…”

Section: Properties Of Active Centers In Csx Catalystsmentioning

confidence: 99%

Investigating the Role of Cs Species in the Toluene–Methanol Side Chain Alkylation Catalyzed by CsX Catalysts

Zhang,

Wang,

Gao

et al. 2024

Catalysts

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The side chain alkylation of toluene with methanol was studied on a series of CsX catalysts prepared by varying the Cs species and ion exchange conditions. The effects of various parameters, such as the exchanging temperatures and times on the adsorption/activation properties of different CsX catalysts, were investigated by combining a variety of characterization means for understanding the role of Cs species in the side chain alkylation reaction. On the basis of the various characterization results and their related literature results, it can be proposed that the Cs ions located on the ion-exchanged sites of X zeolites could effectively adsorb and activate toluene molecularly through modifying the basicity of framework oxygen, whereas the cluster of cesium oxide (Cs2O) could ensure the effective conversion of methanol into formaldehyde. Additionally, Cs ions can promote the production of monodentate formate, which enhances the selectivity of styrene. However, too much Cs2O will lead to the excessive decomposition of methanol into CO2, CO, and H2, thus inhibiting the production of styrene. In summary, the presence of suitable amounts of Cs ions and Cs2O clusters plays a significant role in the formation of the side chain products of styrene and ethylbenzene.

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Intergrowth MFI Zeolite with Inverse Al Zoning and Predominant Sinusoidal Channels for Highly Selective Production of Styrene

Hong,

Deng,

Wang

et al. 2024

Inorg. Chem.

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ZSM-5 zeolites with accessible micropore architecture and tunable acid−base sites are important shape-selective catalysts. However, the presence of exposed straight channels and the external acid−base sites of conventional ZSM-5 has a negative impact on shape selectivity. Herein, we report on the direct synthesis of an intergrowth ZSM-5 zeolite mimicking the mortise− tenon joints. It can be revealed by various methods that the mortise−tenon ZSM-5 shows an inverse Al gradient from the surface to the core of the zeolite. More importantly, the sinusoidal channels predominantly opened to their external surfaces are constructed. The shape-selective capability of the ZSM-5 zeolite has been fully exploited due to the intrinsic inert external surface and unique sinusoidal channel features, thereby resulting in high styrene selectivity (>90%) and good catalytic stability (>100 h) in the toluene side-chain alkylation reaction. In addition, in situ DRIFTS confirms that this intergrowth ZSM-5 contributes to the formation of more active intermediates of HCOO* and H 3 CO*, which is another reason responsible for the superior performance.

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Formation and Function of Formate in the Side-Chain Alkylation of Toluene with Methanol

Cited by 3 publications

References 14 publications

Restructuring Surface Lewis Pairs of FAU Zeolite through N Doping for Boosting the Toluene Side-Chain Alkylation Performance

Restructuring Surface Lewis Pairs of FAU Zeolite through N Doping for Boosting the Toluene Side-Chain Alkylation Performance

Investigating the Role of Cs Species in the Toluene–Methanol Side Chain Alkylation Catalyzed by CsX Catalysts

Intergrowth MFI Zeolite with Inverse Al Zoning and Predominant Sinusoidal Channels for Highly Selective Production of Styrene

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