Effects of carrier gases in the toluene disproportionation on HZSM-5 zeolite

Schulz‐Ekloff, G.; Jaeger, N. I.; Vladov, Ch.; Petrov, L.

doi:10.1016/s0166-9834(00)80584-9

Cited by 24 publications

(15 citation statements)

References 13 publications

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“…The effect of temperature on the catalysts performance could be explained as being a consequence of the faster reduction of Lewis acidic sites density, measured as adsorbed pyridine, when the temperature is increased. Consequently, the ratio of Brönsted-to-Lewis acidic sites density increases and, therefore, the desirable effect claimed by Matsuda et al [26] and Schulz-Ekloff et al [27] is obtained.…”

Section: Discussionmentioning

confidence: 91%

“…On the contrary, olefins are the result of a less hydrogen transfer [36]. However, the use of hydrogen as carrier gas was proposed as a mechanism to provide the desirable concentration of the strong acid sites in order to control the selectivity of the DBI reaction and avoid undesirable side reactions [26,27].…”

Section: Discussionmentioning

confidence: 99%

“…The use of hydrogen as carrier gas was proposed as a mean to provide the adequate amount of protons to the DBI reaction and as a mechanism to control reaction selectivity and avoid undesirable side reactions [26,27]. In this work, two catalysts: SO 4 = /ZrO 2 -Al 2 O 3 and SO 4 = /NiO-Al 2 O 3 , were tested for a-hexene DBI reaction at temperatures from 100 to 200°C.…”

Section: Introductionmentioning

confidence: 99%

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1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

et al. 2008

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Sulfated mixed oxides, SO 4 = /Ni-Al-O and SO 4 = / Zr-Al-O were evaluated for double bond isomerization (DBI) of 1-hexene using helium and hydrogen as carrier gases. The increase of temperature from 100 to 200°C seems to favor the deprotonation pathway and contribute to increase the 1-hexene conversion for both catalysts and without regard of the carrier gas. The results indicate that temperature it is the main factor that contributes to improve both conversion and selectivity towards (cis ? trans)-2-hexene, while the reductive atmosphere beneficiate only the SO 4 = /Ni-Al-O catalyst performance, as hydrogen prevents this catalyst from a fast deactivation.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

et al. 2008

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“…The influences of carrier gases on catalytic activity and stability of zeolites in monoalkylbenzene disproportionation reaction have been the focus of several studies [9,[15][16][17][18] in which hydrogen (H 2 ) and nitrogen (N 2 ) were the two most popular candidates for the study of CGE (carrier gas effect). For example, the effect of H 2 carrier gas on catalytic activity has been reported by Gnep and Guisnet [15] for toluene conversion on mordenite zeolite and for ethylbenzene disproportionation on 0.2 wt% Pt/LaNaX zeolite.…”

Section: Introductionmentioning

confidence: 99%

“…The decrease in catalytic activity is attributed either due to the decrease in the concentration of intermediate benzylic carbocations [15,16] or the decrease in Brønsted acidity; both interpretations need the activation of molecular H 2 . Schulz-Ekloff et al [17] investigated the variations of the catalyst conversion rate in the existence of different carrier gases. The authors disclosed that, under elevated pressures ([0.1 MPa), the degree of conversion during toluene disproportionation on H-ZSM-5 follows the trend H 2 \ He \ N 2 \ Ar.…”

Section: Introductionmentioning

confidence: 99%

Effect of N2 and O2 on selective disproportionation of xylene mixed ethylbenzene over highly active silylated HZSM-5

Nandiwale

Bokade

2013

Appl Petrochem Res

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The influence of carrier gases such as nitrogen and air (78 % N 2 and 21 % O 2 ) on catalytic activity and its stability etc., over modified H-ZSM-5 (pore size regulated by silylation) for the selective formation of Para-diethylbenzene (p-DEB) by xylene mixed ethylbenzene (EB) disproportionation is discussed. The comparison of plane and modified HZSM-5 catalysts using different carrier gases viz., nitrogen and air on pure EB and xylene mixed EB feeds are presented. The disproportionation reaction with xylene mixed EB feed in the presence of air over HZSM-5TS (8 % silica deposited) is observed to be more active and selective as far as p-DEB formation is concerned. Reaction kinetics of EB disproportionation with first-order power law model at different temperatures and W/F (weight of the catalyst/reactant feed rate), with pure EB and xylene mixed EB feed are also discussed. The reaction rate constants are within 0.0668-0.0969 dm 3 /g h and the activation energy of the reaction is calculated to be 30.16 kJ/mol. The catalyst stability (100 h) in the presence of carrier gas is also studied in detail.

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Catalytic Para‐Xylene Maximization. V. Toluene Methylation with Methanol and Disproportionation of Toluene Using Pt/ZSM‐5 and Pt/Mordenite Catalysts

Aboul-Gheit¹,

Aboul-Fotouh²,

Emam³

et al. 2004

J Chinese Chemical Soc

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Toluene was methylated with methanol and disproportionated using catalysts containing different Pt contents (0.2, 0.4 and 0.6%) supported on H‐ZSM‐5 or H‐mordenite (H‐M) zeolites in a fixed‐bed flow‐reactor operated atmospherically at temperatures of 300–500 °C in a flow of hydrogen. Platinum dispersion in the zeolite supports and acid sites strength distribution were evaluated using hydrogen chemisorption (1:1 stoichiometry) and ammonia temperature programmed desorption (TPD) in a differential scanning calorimeter (DSC). Toluene methylation was much faster on all catalysts than toluene disproportionation (DISP). Both reactions were more accelerated using H‐ZSM‐5 containing catalysts than H‐M containing catalysts. The yield of xylenes, and in particular para‐xylene, was significantly influenced by the yield of trimethylbenzenes (TMBs) in product. The selectivities for para‐, ortho‐ and meta‐xylenes production were found largely dependent on the Pt content in the catalysts, particularly when supported on H‐ZSM5‐zeolite. However, using Pt/H‐M catalysts, these selectivities were not strictly controlled by Pt content in the catalysts.

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Effects of carrier gases in the toluene disproportionation on HZSM-5 zeolite

Cited by 24 publications

References 13 publications

1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

1-Hexene Double Bond Isomerization Reaction Over SO 4 = Promoted NiO, Al2O3 and ZrO2 Acid Catalysts

Effect of N2 and O2 on selective disproportionation of xylene mixed ethylbenzene over highly active silylated HZSM-5

Catalytic Para‐Xylene Maximization. V. Toluene Methylation with Methanol and Disproportionation of Toluene Using Pt/ZSM‐5 and Pt/Mordenite Catalysts

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