Isotopic Tracer Studies of Propane Reactions on H−ZSM5 Zeolite

Biscardi, Joseph A.; Iglesia, Enrique

doi:10.1021/jp9824860

Cited by 46 publications

(61 citation statements)

References 29 publications

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“…3b) results in a good description of the formation of butanes and has no noticeable effect on ethane formation. These results allow us to conclude that at low propane conversions over H-ZSM-5 ethane is formed in the HT steps involving propane and adsorbed ethene molecules, and not in the steps of ethene hydrogenation, as was assumed earlier by Biscardi and Iglesia (1998) and . Also, based on the data shown in Figs.…”

Section: Reaction Stepsupporting

confidence: 72%

“…In fact, Price et al (1998) have shown that C 5 and C 6+ alkanes are not normally observed in the reaction mixture, or observed in very small concentrations because of their fast cracking into lower alkanes and alkenes. Furthermore, alkenes, once formed in the PC steps, participate in the fast oligomerization-cracking steps that control alkene distribution during alkane aromatization process (Biscardi and Iglesia, 1998;Haag, 1984;Lukyanov et al, 1995).…”

Section: Alkene Oligomerization-cracking Over Zeolite Acid Sites (10 mentioning

confidence: 99%

“…According to the literature (Biscardi and Iglesia, 1998;Gnep et al, 1987;Guisnet and Gnep, 1996;Haag, 1984;Kitagawa et al, 1986;Lukyanov et al, 1995), the aromatization of light alkanes over ZSM-5 catalysts can be schematically represented as a three-stage process ( Fig. 1) …”

Section: Introductionmentioning

confidence: 99%

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Combined experimental and kinetic modelling studies of the pathways of propane and n-butane aromatization over H-ZSM-5 catalyst

Nguyen

Vazhnova

Kolaczkowski

et al. 2006

Chemical Engineering Science

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Section: Reaction Stepsupporting

confidence: 72%

Section: Alkene Oligomerization-cracking Over Zeolite Acid Sites (10 mentioning

confidence: 99%

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Combined experimental and kinetic modelling studies of the pathways of propane and n-butane aromatization over H-ZSM-5 catalyst

Nguyen

Vazhnova

Kolaczkowski

et al. 2006

Chemical Engineering Science

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“…NH 4 -ZSM5 was treated in ambient air at 398 K overnight and then at 773 K in flowing dry air (Airgas, zero grade) for 20 h to form H-ZSM5. The synthesis and characterization of the H-ZSM5 samples have been reported elsewhere [17][18][19].…”

Section: Experimental Methodsmentioning

confidence: 99%

Catalytic desulfurization of thiophene on H-ZSM5 using alkanes as co-reactants

Waku

Iglesia

2003

Applied Catalysis A: General

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Propane, n-hexane, n-decane, and hydrogen were used as co-reactants in the desulfurization of thiophene catalyzed by H-ZSM5 at 673 K. These co-reactants lead to hydrogen-rich intermediates, which are required for the removal of unsaturated fragments formed in thiophene decomposition reactions. Thiophene desulfurization rates increased with increasing alkane chain size, suggesting that the availability of hydrogen-rich intermediates increases with increasing alkane reactivity. Desulfurization rates with alkane co-reactants were significantly higher than those achieved with hydrogen. Sulfur is predominately removed as hydrogen sulfide (>80% S-selectivity) in the presence of alkane co-reactants, but much lower hydrogen sulfide selectivities were obtained when hydrogen was used and when thiophene decomposed in the absence of any co-reactants. The presence of thiophene did not alter the nature of the cracking, dehydrogenation, oligomerization, and cyclization pathways typical of alkane reactions or the overall rates of propane conversion on H-ZSM5. The selectivity for alkane conversion to aromatics, however, increased when alkane reactions occur concurrently with thiophene desulfurization, indicating that thiophene-derived intermediates contribute to the formation of aromatics by scavenging alkene intermediates formed from the alkane co-reactants. The higher alkene/alkane ratios observed during alkane reactions in the presence of thiophene are consistent with the scavenging of hydrogen-rich intermediates by thiophene-derived species via reactions that form aromatic molecules containing carbon atoms from both alkane and thiophene reactants.

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“…Then, subsequent alkene oligomerization and cracking, and finally main aromatics such as benzene, toluene and xylenes (BTX) were formed through a sequence of cyclization and hydride transfer steps including diene formation from hydride transfer of alkenes, cyclization of dienes and hydride transfer of cyclodienes [36,40,41]. The reaction rate is generally considered as an order of alkene oligomerization and cracking [ aromatization [ alkane dehydrogenation [42,43]. Nguyen et al [42] investigated the kinetic model of the reaction pathway of propane and n-butane aromatization over ZSM-5.…”

Section: Effect Of Synthesis Conditions To Para-selectivitymentioning

confidence: 99%

para-Selectivity of silicalite-1 coated MFI type galloaluminosilicate in aromatization of light alkanes

et al. 2015

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MFI type galloaluminosilicates (GaAlMFI) were coated with inert silicalite-1 layers. The silicalite-1 coating could improve the para-selectivity for xylene production in aromatization of propane. In the silicalite-1 coating step, low alkali concentration in the synthesis solution enhanced para-selectivity. A proton-exchange procedure also had an impact on the para-selectivity. Significant decrease of para-selectivity was observed over the silicalite-1 coated GaAlMFI with repeated proton-exchange. From the 71 Ga and 27 Al MAS NMR measurements, demetalation occurred during the proton-exchange process, and those metal species is likely to become catalytically active sites without para-selectivity. From the aromatization of propane and n-butane, para-selectivity in n-butane aromatization was found to be higher than that in propane aromatization. From the product distribution, naphthalene and its derivatives were easier to be produced in propane aromatization compared to n-butane aromatization. The formation of naphthalene and its derivatives may relate to decrease in the para-selectivity in propane aromatization.

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Isotopic Tracer Studies of Propane Reactions on H−ZSM5 Zeolite

Cited by 46 publications

References 29 publications

Combined experimental and kinetic modelling studies of the pathways of propane and n-butane aromatization over H-ZSM-5 catalyst

Combined experimental and kinetic modelling studies of the pathways of propane and n-butane aromatization over H-ZSM-5 catalyst

Catalytic desulfurization of thiophene on H-ZSM5 using alkanes as co-reactants

para-Selectivity of silicalite-1 coated MFI type galloaluminosilicate in aromatization of light alkanes

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