Creation of silanol nests on HZSM-5 catalyst to boost the alkylation of toluene with methanol for PX synthesis

Hou, Guoqiang; Fu, Tingjun; Li, Xin; Ma, Qian; Li, Zhong

doi:10.1016/j.apcata.2022.118713

Cited by 15 publications

(7 citation statements)

References 44 publications

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“…The coke species of spent Zn60 and spent HZ440 at different reaction stages were further analyzed by FT-IR. It can be seen from Figure a that the infrared characteristic peaks of the CC double bond (1585 cm –1 ) and C–H band (3030 cm –1 ) that belonged to aromatics species were gradually increased for spent Zn60 in Zn60&HZ440 mixed catalysts with the extension of reaction time. ,, In addition, the absorption peaks attributed to CO stretching vibration (1723 cm –1 ) and C–O stretching vibration (1247 and 1154 cm –1 ) were gradually enhanced, indicating that oxygen-containing coke species were also gradually increased as the reaction time progressed. ,, Also, these picks at 1723 and 1247 cm –1 of deactivated S-Zn60(M4-1:3-34h) were obviously higher than that of S-Zn60(S), suggesting that the introduction of HZ440 grains promoted the generation of oxygen-containing coke species over Zn60 grains.…”

Section: Resultsmentioning

confidence: 96%

“…The IR spectra were recorded at room temperature after the desorption of pyridine molecules at 400 °C for 30 min. The extinction coefficients of 1.88 and 1.42 cm mmol –1 were used for the calculation of Brønsted acid concentration and Lewis acid concentration according to previous reports, respectively. , …”

Section: Methodsmentioning

confidence: 99%

“…25,50,51 In addition, the absorption peaks attributed to C�O stretching vibration (1723 cm −1 ) and C−O stretching vibration (1247 and 1154 cm −1 ) were gradually enhanced, indicating that oxygencontaining coke species were also gradually increased as the reaction time progressed. 37,51,52 Also, these picks at 1723 and 1247 cm −1 of deactivated S-Zn60(M4-1:3-34h) were obviously higher than that of S-Zn60(S), suggesting that the introduction of HZ440 grains promoted the generation of oxygencontaining coke species over Zn60 grains. Further, as shown in Figure 9b, the spent HZ440 catalysts showed extremely high absorption peaks at 1247 cm −1 and 1154 cm −1 , which were gradually enhanced as the reaction time progressed.…”

Section: Analysis Of Coking and Inactivationmentioning

confidence: 99%

“…The extinction coefficients of 1.88 and 1.42 cm mmol −1 were used for the calculation of Brønsted acid concentration and Lewis acid concentration according to previous reports, respectively. 36,37 The external accessible acid sites of the synthesized catalyst were investigated through tert-butylamine titration measurement according to previous reports. 38 −40 Before the test, a 50 mg sample was absolutely dispersed in 60 mL acetonitrile and continuously stirred for 4 h. Then, the suspension was titrated by 0.01613 mol/ml tertbutylamine solution in acetonitrile using a Leici ZDJ-5 potentiometric titration meter.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

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Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

Zhang

Han

et al. 2023

ACS Catal.

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The catalytic conversion of hydrocarbon molecules over an acidic silica-aluminum molecular sieve is the core of the petrochemical and coal chemical industry. Finely controlling the reaction process between catalyst grains for catalytic stability and product selectivity can be achieved by configuring zeolites with different acid properties, but the details continue to be indefinable. Herein, mixed ZSM-5 with different acid configurations was used as the catalytic platform to study the inter-catalytic behavior of the grains using methanol to aromatics as the model reaction. It was found that the obvious multiple reactions of hydrocarbon intermediates occurred between ZSM-5 grains. The typical C3–C5 hydrocarbons produced from Zn-free ZSM-5 with a low SiO2/Al2O3 ratio could be aromatized on adjacent Zn60 grains. Although the external coke deposition of Zn-free ZSM-5 grains was promoted due to the secondary conversion of returned aromatics, the dealkylation reaction was enhanced on external strong acid sites, which significantly increased the light aromatic selectivity. Decreasing the SiO2/Al2O3 ratio of Zn-free ZSM-5 to 120 could significantly promote the heavy aromatic de-alkylation and inhibited external coke deposition due to the sufficient external strong acid sites. The lifetime of such a mixed catalyst was prolonged nearly 3 times than that of the previously reported olefin-aromatic doubled catalytic system, and the heavy aromatic selectivity was reduced by 30%. This work helps to clarify the catalytic behavior of acidic molecular sieve catalysts in the hydrocarbon conversion reaction and provides an effective path to improve the catalytic performance by configurating different molecular sieve catalysts.

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Section: Resultsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Analysis Of Coking and Inactivationmentioning

confidence: 99%

Section: Catalyst Characterizationmentioning

confidence: 99%

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Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

Zhang

Han

et al. 2023

ACS Catal.

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“…Therefore, it is of commercial and scientific interest to convert excessive benzene to valuable toluene or xylene through an alkylation reaction. Current approaches mainly focus on using methanol, − syngas, − methane, , or CO 2 − as the methylation reagents to react with benzene. Among these, CO 2 -coupled benzene alkylation is considered as a doubly beneficial route, which can not only increase the production of the high value-added toluene and xylene but also utilize CO 2 to alleviate the greenhouse effect …”

Section: Introductionmentioning

confidence: 99%

Integration of Nano-Sized HZSM-5 with ZnZrO_x as a Bifunctional Catalyst to Boost Benzene Alkylation with Carbon Dioxide and Hydrogen

Yin,

Fu,

et al. 2023

ACS Sustainable Chem. Eng.

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Benzene alkylation with CO2/H2 is a doubly beneficial option to upgrade benzene toward valuable products, in which benzene can be converted into valuable toluene and xylene, while CO2 can be utilized as an alkylation reagent to mitigate the greenhouse effect. It is quite challenging to ascertain the critical rule of zeolite regulation for the synergistic effect in oxide-zeolite composite (OXZEO) catalysts, a series of bifunctional catalysts were investigated in this work, consisting of ZnZrO x solid solution and nano-sized HZSM-5 with uniform size distribution and distinct acid properties. Key parameters affecting the catalyst performance were analyzed and optimized in this tandem reaction, namely, the mass ratio of two components, the SiO2/Al2O3 ratio of HZSM-5, and the proximity between ZnZrO x and HZSM-5. Due to the increased active site accessibility originating from nano-sized HZSM-5, the combined selectivity of toluene and xylene reaches 94.6% at 31.3% benzene conversion, respectively. Moreover, low ethylbenzene selectivity (<1%) has been achieved. It is worth noting that the long-term stability test indicates a faster deactivation in the nano-sized HZSM-5 system as compared with the micro-sized counterpart. Based on EDS mappings, it is found that nano-sized HZSM-5 experiences a more severe metal migration issue, resulting in lower catalyst stability. The reaction mechanism with formate-methoxy intermediates and the synergistic effect of CO2 hydrogenation-alkylation were further confirmed by in situ diffuse reflectance infrared Fourier transformations spectroscopy and gas chromatography–mass spectrometry. By correlating zeolite size and acidity with catalytic performances, these findings could facilitate the further rational design of OXZEO catalysts toward CO2 catalytic conversions.

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Pt Nanoparticles on Beta zeolites for Catalytic Toluene Oxidation: Effect of the Hydroxyl Groups of Beta Zeolite**

Zou,

Chansai,

et al. 2023

ChemCatChem

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Stabilisation of metal species using hydroxyl‐rich dealuminated zeolites is a promising method for catalysis. However, insights into the interactions between the hydroxyl groups in zeolite and noble metals and their effects on catalysis are not yet fully understood. Herein, comparative studies were conducted using Pt catalysts supported on hydroxyl‐rich dealuminated Beta (deAl‐Beta) and the pristine proton‐form Beta (H‐Beta) for catalytic oxidation of toluene. The findings suggest that during impregnation the Pt precursor (i.e., Pt(NH3)4(NO3)2) interacted with different sites on deAl‐Beta and H‐Beta, leading to the formation of supported Pt nanoparticles with different physicochemical properties. The resulting Pt/deAl‐Beta exhibited improved activity and anti‐coking ability than Pt/H‐Beta in catalytic toluene oxidation. According to toluene‐TPD, 1H NMR relaxation and in situ DRIFTS characterisation, the enhanced performance of Pt/deAl‐Beta could be ascribed to (i) the active Pt‐O sites stabilised by hydroxyl groups, which interact with toluene easily for conversion, and (ii) the acid‐free feature of the deAl‐Beta support, which avoids the formation of coke precursors (such as benzoate species) on the catalyst surface. Findings of the work can serve as the design guidelines for making effective supported metal catalysts using zeolitic carriers.

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Creation of silanol nests on HZSM-5 catalyst to boost the alkylation of toluene with methanol for PX synthesis

Cited by 15 publications

References 44 publications

Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

Integration of Nano-Sized HZSM-5 with ZnZrO_x as a Bifunctional Catalyst to Boost Benzene Alkylation with Carbon Dioxide and Hydrogen

Pt Nanoparticles on Beta zeolites for Catalytic Toluene Oxidation: Effect of the Hydroxyl Groups of Beta Zeolite**

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Creation of silanol nests on HZSM-5 catalyst to boost the alkylation of toluene with methanol for PX synthesis

Cited by 15 publications

References 44 publications

Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

Integration of Nano-Sized HZSM-5 with ZnZrOx as a Bifunctional Catalyst to Boost Benzene Alkylation with Carbon Dioxide and Hydrogen

Pt Nanoparticles on Beta zeolites for Catalytic Toluene Oxidation: Effect of the Hydroxyl Groups of Beta Zeolite**

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Product

Resources

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Integration of Nano-Sized HZSM-5 with ZnZrO_x as a Bifunctional Catalyst to Boost Benzene Alkylation with Carbon Dioxide and Hydrogen