Low-temperature test reaction for hydride transfer on solid acid catalysts

Platon, Alexandru; Thomson, W. W.

doi:10.1007/s10562-005-3741-9

Cited by 11 publications

(5 citation statements)

References 16 publications

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“…Controlling the zeolite acid site density and optimum dispersion of these acid sites is crucial in minimizing hydrogen transfer [14,72,85]. Reducing the number of acid sites may be accomplished by minimizing the zeolite unit cell size (UCS) [85].…”

Section: Effect Of Hydrogen Transfer Indexmentioning

confidence: 99%

Maximizing propylene production via FCC technology

2015

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This review looks at the main processes available for the production of light olefins with a focus on maximizing the production of propylene. Maximization of propylene production has become the focus of most refineries because it is in high demand and there is a supply shortage from modern steam crackers, which now produce relatively less propylene. The flexibility of the fluid catalytic cracking (FCC) to various reaction conditions makes it possible as one of the means to close the gap between supply and demand. The appropriate modification of the FCC process is accomplished by the synergistic integration of the catalyst, temperature, reaction-residence time, coke make, and hydrocarbon partial pressure. The main constraints for maximum propylene yield are based on having a suitable catalyst, suitable reactor configuration and reaction conditions.

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Section: Effect Of Hydrogen Transfer Indexmentioning

confidence: 99%

Maximizing propylene production via FCC technology

2015

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“…Consequently, the n-butane yield is an important indicator for hydride transfer activity. Activity of hydride transfer, which is important for alkylation activity, occurs on catalysts with strong acid sites 20) . Although the findings of the desorption peak temperature of NH3 presented in Table 1 show that H-ZSM-5 had stronger acid sites than H-Y and DGC-H-BEA, n-butane yield was not so high over H-ZSM-5 compared to DGC-H-BEA.…”

Section: Catalytic Activities Of Various Zeolitesmentioning

confidence: 99%

H-ベータゼオライトを用いたcstr中でのイソブタンの1-ブテンによるアルキル化（第1報）ゼオライトの構造および合成法のアルキル化反応への影響

Sekine

Ichikawa

Tajima

et al. 2012

J. Jpn. Petrol. Inst.

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The effects of zeolite structures on alkylation of isobutane with 1-butene were investigated in a batch reactor and in a continuously stirred tank reactor (CSTR) using the proton-form zeolites, H-ZSM-5, H-L, H-Y, and H-BEA (beta). H-ZSM-5 and H-L zeolite catalysts were deactivated rapidly, whereas H-Y and H-BEA zeolites retained catalytic activity for a long time in the CSTR, implying that zeolites with three-dimensional large pore systems are useful for preventing deactivation of the catalyst during alkylation of isobutane with 1-butene. H-BEA synthesized using a dried-gel method (DGC-H-BEA) showed the most stable activity among the various H-BEA zeolites. The effects of the synthesis methods and zeolite characteristics were investigated using H-BEA zeolite. Characterization using NH3-TPD and pyridine-sorption monitored by FT-IR showed that high acid density and high Brønsted acid ratio promoted alkylation of isobutane with 1-butene over H-BEA zeolite.

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“…16,17 Product distribution obtained from bimolecular alkane reactions is potentially interesting for the evaluation of the HT capability of solid acids. However, the validity of the results depends on the system chosen as model reaction.…”

Section: Introductionmentioning

confidence: 99%

A theoretical study of the hydride transfer between 1-Adamantyl cation and isopentane

Oliveira¹,

Rosenbach²,

Santos³

et al. 2010

J. Braz. Chem. Soc.

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Foi realizado um estudo teórico da transferência de hidreto entre o cátion 1-adamantila e isopentano, usando a teoria do funcional da densidade em nível PBE1PBE/6-31G (d,p). Os resultados indicaram que há formação de um íon carbônio como intermediário, que é mais estável que os complexos de van der Waals entre os íons carbênios e os alcanos. Os fatores entrópicos são bastante importantes e sobrepujam o termo entálpico à temperatura ambiente.A density functional teory study of the hydride transfer between 1-adamantyl cation and isopentane has been performed at the PBE1PBE/6-31G(d,p) theoretical level. The results indicate that a carbonium ion is involved as intermediate and is more stable than the van der Waals complexes between the carbenium ions and the alkanes. Entropic factors are important and overcome the enthalpic term at room temperature. Keywords: hydride transfer, carbocations, adamantane, isopentane IntroductionIntermolecular or bimolecular hydride transfer (HT) is a crucial step in acid-catalyzed hydrocarbon transformations. This reaction is involved in the propagation of the catalytic cycle of cracking 1,2 and alkylation 3 of hydrocarbons, as well as in the formation of aromatic hydrocarbons 4 in gasoline and coke, 5,6 which are carbonaceous materials deposit over the catalyst surface that may lead to loss of activity. Conceptually, HT involves the bimolecular transfer of a hydride from an alkane to a carbenium ion (Scheme 1). R⊕ + R'-H → R-H + R'⊕ Scheme 1. Schematic representation of hydride transfer reactions.In the gas phase, HT is much slower than proton transfer 7 and shows a negative temperature dependence. [8][9][10] The reaction is believed to occur via formation of a "tight" complex, 11,12 whose structure may resemble a carbonium ion, 13 formed by the interaction of the empty p-orbital of a carbenium ion with the C-H bond of the alkane. The reaction is used 14,15 to assess the carbenium ion stability in the gas phase.In condensed phase, especially on zeolites and other solid acid catalysts, there are few studies regarding hydride transfer. 16,17 Product distribution obtained from bimolecular alkane reactions is potentially interesting for the evaluation of the HT capability of solid acids. However, the validity of the results depends on the system chosen as model reaction. Indeed, variation of the hydride acceptor seems to affect the rates of hydride transfer to a considerably greater extent, than an equal change of the thermodynamic driving force caused by variation of the hydride donor. 18 In addition, some systems involve simultaneous reactions competing with HT, and may significantly affect the interpretation of the results.The 1-adamantyl cation is a stable species 19 and can be synthesized from the 1-adamantanol and fluorosulfonic acid-antimony pentafluoride. 20 On the zeolite surface, this species can be also generated from its halide. 21 In addition de Oliveira et al. 2181 Vol. 21, No. 12, 2010 to the stabilization by sC-C bond hyperconjugation, the 1-adamantyl cation has a cage ...

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Low-temperature test reaction for hydride transfer on solid acid catalysts

Cited by 11 publications

References 16 publications

Maximizing propylene production via FCC technology

Maximizing propylene production via FCC technology

H-ベータゼオライトを用いたcstr中でのイソブタンの1-ブテンによるアルキル化（第1報）ゼオライトの構造および合成法のアルキル化反応への影響

A theoretical study of the hydride transfer between 1-Adamantyl cation and isopentane

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