Kinetics modeling of disproportionation and ethylation of ethylbenzene over HZSM-5: Effects of SiO2/Al2O3 ratio

Osman, Mogahid; Atanda, Luqman; Hossain, Mohammad M.; Al-Khattaf, S.

doi:10.1016/j.cej.2013.02.040

Cited by 20 publications

(17 citation statements)

References 35 publications

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“…There is an increase in both extra-framework and framework aluminum as the Si/Al ratio decreases, promoting the formation of Brønsted and Lewis acid sites [12]. As indicated before, Lewis acid sites do not participate in xylene isomerization but they can strengthen the acidity of Brønsted sites [5]; therefore, an optimum balance between both types of acid sites is the goal in tailoring the catalyst for a particular service [8,13]. For instance, Nayak and Choudhary [10] found maximum conversion but minimum selectivity over ZSM-5 at an Si/Al ratio of 17.2.…”

Section: )mentioning

confidence: 93%

“…Disproportionation needs higher concentrations of acid sites [9] and the strength of these sites follows the trend: isomerization < dealkylation < disproportionation [10,11]. The acidity of zeolites is determined by their Si/Al ratio, with the total number of acid sites decreasing with increasing Si/Al ratio due to the lower amount of Al [2,5,12,13]. The strength of each site is enhanced by their separation among them, up to a maximum given by the specific topology of the zeolite [5,14].…”

Section: Introductionmentioning

confidence: 99%

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Xylene Isomerization in the Liquid Phase Using Large‐Pore Zeolites

Gonçalves

Rodrigues

2015

Chem Eng & Technol

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Three large-pore zeolites, Beta with Si/Al ratios of 25 and 35 and Mordenite with an Si/Al ratio of 30, were studied in the conversion of o-xylene at 493 K. Maximum conversion was achieved by the catalyst with the highest Si/Al ratio due to faster diffusion of the isomer inside the zeolite channels because of the lower acidity of the solid even with larger crystal size. A kinetic study was then carried out over this catalyst between 473 and 513 K in a batch reactor in the liquid phase. The activation energies obtained do not indicate the presence of diffusional constraints towards any isomer. Finally, the kinetic model obtained was simulated in a fixed-bed reactor and compared to ZSM-5 in the temperature range from 493 to 533 K. An increment in p-xylene production of 20 % on average was obtained.

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Section: )mentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Xylene Isomerization in the Liquid Phase Using Large‐Pore Zeolites

Gonçalves

Rodrigues

2015

Chem Eng & Technol

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“…It is commonly considered as proceeding via a carbenium ion-type mechanism [22]. The ethylation of benzene with ethanol has been proposed to take place by the reaction of the activated alkene (formed by dehydration of the alcohol) on the acid sites of the zeolite [23,24]. Scientists and researchers have developed different catalysts to make ethanol dehydration more industrial friendly to enhance ethylene yield and lower reaction temperature.…”

Section: Resultsmentioning

confidence: 99%

“…Various types of zeolites, such as mordenite, USY, Beta, MCM-22 and ZSM-5 catalysts show good catalytic activity and stability in ethylbenzene disproportionation/alkylation using different types of reactor and reaction conditions. The disproportionation of ethylbenzene gives rise to diethylbenzene and benzene [24].…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, the above reaction temperature of 400°C, transalkylation reaction and Ethylbenzene disproportionation were played an important role, thereby decreased conversion of benzene. According to Osman et al (2013), the catalytic experiment in the CREC Riser Simulator showed that low temperature favours the EB ethylation reaction while higher temperature is favourable for disproportionation. The effect of reaction temperature on selectivity of ethylbenzene over Mg (5 %)-B (4 %)-HZSM-5 catalyst for the above-stated ratio of feed is also shown in Fig.…”

Section: Boron Modified Hzsm-5 Zeolite Catalystmentioning

confidence: 99%

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Alkylation of benzene with ethanol over modified HZSM-5 zeolite catalysts

Emana

Chand

2015

Appl Petrochem Res

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Alkylation of benzene with ethanol was analysed using unmodified as well as modified shape selective HZSM-5 (Si/Al = 31) zeolite catalysts. The reaction was carried out in a continuous fixed bed flow reactor in the temperature range of 300-500°C at atmospheric pressure to investigate the activity of various catalysts for the selectivity and yield of ethylbenzene (the desired product). The alkylation of benzene with ethanol (2:1 by volume) produces ethyl benzene as primary product and others like diethylbenzene, triethylbenzene and xylene mixtures as secondary products. The modification of HZSM-5 was done by impregnation using boron and magnesium. The modification caused changes in the surface area, acidity and pore volume of zeolite sample. The physiochemical properties of catalysts were characterised by XRD, TEM, BET, TGA, FTIR, NH 3 -TPD and SEM. The feed and products were analysed by gas chromatography. The conversion of benzene was found to be better in bi metallic (B and Mg) modified HZSM-5 followed by unmodified HZSM-5. The modified catalysts gave better selectivity (72.8 %) and yield (38.1 %) of ethylbenzene.

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Evaluation of Major Product Distribution Using Experimental‐Theoretical Comparative Studies on Toluene and Ethylbenzene Ethylation over Catalysts Zeolite MCM‐22 and Modified MCM‐22

Thakkar

Bandyopadhyay

2019

ChemistrySelect

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The activity of zeolite MCM-22 and modified MCM-22 catalyst were tested in the vapor phase alkylation of toluene and ethylbenzene by ethanol to investigate the influence of thermodynamic parameters, reaction temperature, and the molar ratio of toluene and ethylbenzene to ethanol. The reactions were evaluated with experimental and theoretical approaches. The catalysts were characterized by XRD, FE-SEM, TGA, N 2 -adsorption, and NH 3 & Py-TPD analyses. The superior catalytic performance of modified MCM-22 was observed in ethylation of ethylbenzene and ethylation of toluene. The catalytic performance indicates that zeolite MCM-22 retained shape selectivity resulting into para-selectivity, while modified MCM-22 possessed more mesopores and increased accessibility to the acid sites thereby increasing conversion of ethylbenzene.

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Kinetics modeling of disproportionation and ethylation of ethylbenzene over HZSM-5: Effects of SiO2/Al2O3 ratio

Cited by 20 publications

References 35 publications

Xylene Isomerization in the Liquid Phase Using Large‐Pore Zeolites

Xylene Isomerization in the Liquid Phase Using Large‐Pore Zeolites

Alkylation of benzene with ethanol over modified HZSM-5 zeolite catalysts

Evaluation of Major Product Distribution Using Experimental‐Theoretical Comparative Studies on Toluene and Ethylbenzene Ethylation over Catalysts Zeolite MCM‐22 and Modified MCM‐22

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