Catalysis of metal supported zeolites for dealkylation–transalkylation of alkyl-aromatics

Al-Khattaf, S.; Ali, Syed A.; Al-Nawad, K.; Chiu, Chih-Hsuan; Tsai, Tseng-Chang

doi:10.1016/j.apcata.2016.01.015

Cited by 15 publications

(9 citation statements)

References 34 publications

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“…With the dispersed Pt cluster size typically of 1.3 nm and since the intra crystalline pore diameter of Beta is 0.67 nm, the platinum must be predominantly located on the external crystalline surfaces of the zeolite. The location and level of dispersion observed was in line with a previous study where comparison of metal loading methods demonstrated much higher dispersion obtained when using impregnation as opposed to ion exchange …”

Section: Resultssupporting

confidence: 91%

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Transalkylation of Toluene with 1,2,4-Trimethylbenzene over Large Pore Zeolites

Almulla

Zholobenko

Hill³

et al. 2017

Ind. Eng. Chem. Res.

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Using industrially relevant operating parameters, the transalkylation of 1,2,4-Trimethylbenzene (TMB) with toluene was studied. The effect of acidity and structure, increased reaction pressure and very low levels of Pt impregnation have been investigated over both H-form and Pt-loaded zeolites: Beta, MOR, and Y. A fixed bed reactor was used at WHSV of 5 h-1 , 400 o C and a 50:50 wt. % Toluene:TMB ratio with the order of activity after 50 h TOS of Y > Beta >> MOR at 1 bar. At elevated pressure (10 bar), all catalysts showed better performance with significant improvement in MOR as pore blockage reduced and the order of activity was Beta > MOR > Y. Incorporation of Pt (0.08wt. %) further improved the activity of all catalysts with the highest conversion after 50 h TOS over Beta (62 wt. %) where Beta and MOR yielded similar levels of xylenes (40 wt. %). All catalysts were further optimized for activity whilst maintaining the desired stability and highest xylenes yield.

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Section: Resultssupporting

confidence: 91%

“…The location and level of dispersion observed was in line with a previous study where comparison of metal loading methods demonstrated much higher dispersion obtained when using impregnation as opposed to ion exchange. 29 3.2. Effect of Pressure on the Catalytic Activity of Large Pore Zeolites.…”

Section: X-ray Diffraction and Scanning Electron Microscope (Sem)mentioning

confidence: 99%

Transalkylation of Toluene with 1,2,4-Trimethylbenzene over Large Pore Zeolites

Almulla

Zholobenko

Hill³

et al. 2017

Ind. Eng. Chem. Res.

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“…Pt/mZSM-5 exhibited a very low olefins/paraffins ratio of 0.11 which means most olefins formed via MTO process were hydrogenated to paraffins. , In this regard, the hydrogenation reaction may promote MTO process equilibrium to be shifted toward products so that more methanol is used to generate light hydrocarbons. Furthermore, the low olefins/paraffins ratio may suppress the formation of higher alkylated products which can produce xylenes through transalkylation or dealkylation reactions. − The observation of decreased toluene conversion, methanol usage for alkylation, and yield of para-xylene over Pt/mZSM-5 under hydrogen can be explained by both counts. In brief, carrier gas effect on mZSM-5 (a representative ZSM-5 based catalyst modified by oxides) is that more coke deposits are generated under inert nitrogen than reactive hydrogen.…”

Section: Resultsmentioning

confidence: 99%

Methanol Usage in Toluene Methylation over Pt Modified ZSM-5 Catalyst: Effects of Total Pressure and Carrier Gas

Wang

Zhang

Zuo

et al. 2017

Ind. Eng. Chem. Res.

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The present study investigates the effects of total pressure and carrier gas on toluene methylation using two modified ZSM-5 based catalysts impregnated with or without platinum. Toluene alkylation with methanol was carried out not only at different reaction pressure under nitrogen or hydrogen but also at different total pressure while the partial pressure of reactants remained constant. The amount of coke formed on the catalysts was less under hydrogen atmosphere. However, the hydrogenation reaction catalyzed by Pt modified catalyst promoted methanol conversion to undesired methane and light hydrocarbons, which in turn decreased the toluene conversion. For both carrier gases, it was found that methanol usage toward undesired byproducts increased with total pressure. Such a trend suggests that a higher total pressure results in a lower toluene and methanol adsorption complexes formation rate in the ZSM-5 pores, and therefore the toluene conversion decreased. The hydrogenation reaction and the higher total pressure simultaneously increased the selectivity of methanol converted to light hydrocarbons and methane, which led to the deteriorated catalytic performance of Pt modified catalysts at elevated reaction pressure.

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“…Regarding the second approach, metal impregnation in MCM-36, examples include Au supported on the titanosilicate-pillared MCM-36 for epoxidation [18], Vsupported MCM-36 for oxidative dehydrogenation [19], Pt-supported MCM-36 for dealkylation and transalkylation [20] and Zn-, Au-, Ag-, Au-Zn-, Ag-Zn-and AuAg-Znsupported MCM-36 for methanol oxidation [21]. So far, no studies have been dedicated to the synthesis and catalytic behavior of Nb-impregnated MCM-36 materials.…”

Section: Introductionmentioning

confidence: 99%