Mechanistic details of acid-catalyzed reactions and their role in the selective synthesis of triptane and isobutane from dimethyl ether

Simonetti, Dante A.; Ahn, John H.; Iglesia, Enrique

doi:10.1016/j.jcat.2010.11.004

Cited by 85 publications

(102 citation statements)

References 47 publications

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“…At similar conditions, methanol conversion over large-pore zeolites proceeds mainly via the arene cycle [25][26][27][28]. However, the reaction conditions are of great importance, as the alkene cycle can be promoted in large-pore zeolites when low temperatures and high pressures are employed [29,30]. Some of the present authors recently demonstrated that the relative importance of the arene and alkene cycle is influenced by the zeolitic acid strength [31,32].…”

Section: Introductionmentioning

confidence: 95%

How zeolitic acid strength and composition alter the reactivity of alkenes and aromatics towards methanol

Erichsen

Wispelaere

Hemelsoet

et al. 2015

Journal of Catalysis

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a b s t r a c tThis work encompasses a combined experimental and theoretical assessment of how zeolitic acid strength and composition affects acid-catalysed methylation reactions. Overall, higher methylation rates were observed over the material with higher acid strength. Co-reactions of methanol with benzene at 250°C over the two isostructural AFI materials H-SSZ-24 and H-SAPO-5 revealed large differences in selectivity. While the stronger acidic H-SSZ-24 mainly produced toluene and polymethylbenzenes, high yields of C 4+ aliphatics were observed over H-SAPO-5. These results strongly suggest that alkene methylation was preferred over H-SAPO-5 even at very low conversion during methanol/benzene co-reactions. Furthermore, a comparison of benzene and propene methylation at 350-400°C revealed a significantly faster rate of benzene than propene methylation in H-SSZ-24, whereas the rates of benzene and propene methylation were similar in H-SAPO-5. The observed difference in reactivity of the two hydrocarbons in both catalysts could be understood by careful analysis of various molecular dynamics simulations of the co-adsorbed complexes. The probability to form protonated methanol was, as expected, higher in the more acidic material. However, in H-SSZ-24, the probability for methanol protonation was higher when co-adsorbed with benzene than when co-adsorbed with propene, while the same was not observed in H-SAPO-5. Furthermore, it was found that benzene and methanol are more likely to form a reactive co-adsorbed complex in H-SSZ-24 compared to propene and methanol, while the opposite was observed for H-SAPO-5. This work shows that molecular dynamics simulations provide insights into the adsorption behaviour of guest molecules in large pore AFI materials. The obtained insights correlate with the experimentally observed reactivities.

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Section: Introductionmentioning

confidence: 95%

How zeolitic acid strength and composition alter the reactivity of alkenes and aromatics towards methanol

Erichsen

Wispelaere

Hemelsoet

et al. 2015

Journal of Catalysis

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“…n-Octane has been hydrocracked on various mordenites, and ratios of 1.1 [55,57] and 0.5 [59] have been found. Simonetti et al [60] converted triptene in the presence of dimethyl ether on H-beta and found a high selectivity to isobutyl product, presumably through methylation and subsequent cracking. Thus, when the zeolite is presented with a triply-methylated C8 species, the species does crack to selectively product isobutane.…”

Section: Evidence That Bimolecular Pathways Dominate At ''High'' Alkementioning

confidence: 99%

Mechanism of n-butane skeletal isomerization on H-mordenite and Pt/H-mordenite

Wulfers

Jentoft

2015

Journal of Catalysis

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“…For a BEA catalyst, experiments based on the simultaneous feeding of DME with labeled carbon atoms and С 3-8 hydrocarbons were conducted [26]. According to the data on the distribution of 13 C in the reaction products and the calculation results of methylation, hydrogen transfer, isomerization, and β scission reaction rates, the probability of occurrence of these reactions was determined (see Table 2).…”

Section: Mechanism and Kineticsmentioning

confidence: 99%

Triptane synthesis from methanol and dimethyl ether: A review

2016

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The review summarizes and analyzes the results of research in the field of triptane synthesis from methanol and dimethyl ether (DME). The reaction with a fairly high triptane yield occurs in the presence of both homogeneous and heterogeneous catalysts. It has been shown that InI 3 and ZnI 2 are the most com monly used catalysts for the homogeneous process, while zeolite systems based on H BEA and H Y are promising catalysts for the heterogeneous process. The effect of the catalyst nature (acidity and structure) on the type of resulting intermediates and the reaction mechanism has been described. Currently available approaches to describing the kinetics of the complex triptane synthesis reaction and the engineering aspects of the process have been discussed.Keywords: high octane component of motor fuel, triptane, triptene, mechanism of triptane synthesis from oxygenates, zinc and indium iodides, H BEA and H Y zeolite catalysts

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Mechanistic details of acid-catalyzed reactions and their role in the selective synthesis of triptane and isobutane from dimethyl ether

Cited by 85 publications

References 47 publications

How zeolitic acid strength and composition alter the reactivity of alkenes and aromatics towards methanol

How zeolitic acid strength and composition alter the reactivity of alkenes and aromatics towards methanol

Mechanism of n-butane skeletal isomerization on H-mordenite and Pt/H-mordenite

Triptane synthesis from methanol and dimethyl ether: A review

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