Chapter 17 Hydrocarbon processing with zeolites

Maxwell, Ian E.; Stork, W.H.J.

doi:10.1016/s0167-2991(01)80259-7

Cited by 67 publications

(35 citation statements)

References 63 publications

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“…Tubular-pore zeolites (e.g., TON-, MTT-, MTW-, GON-, and ZSM-48-type zeolites) are of industrial interest because they absorb and hydroisomerize long linear alkanes (wax), effectively turning them into high-value base oil [31][32][33][34][35][36]. Catalysts based on tubular-pore zeolites have replaced catalysts based on intersecting-pore MFI-type zeolites, which absorb and hydrocrack the long linear alkanes out of the base oil fraction into less-valuable products [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

“…Catalysts based on tubular-pore zeolites have replaced catalysts based on intersecting-pore MFI-type zeolites, which absorb and hydrocrack the long linear alkanes out of the base oil fraction into less-valuable products [32][33][34][35]. The higher hydroisomerization selectivity of the nonintersecting tubular-pore zeolites and the higher hydrocracking selectivity of the intersecting-pore MFItype zeolite result from the way in which these zeolites process hydrocracking precursors.…”

Section: Introductionmentioning

confidence: 99%

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Shape-selective n-alkane hydroconversion at exterior zeolite surfaces

Maesen

Krishna²,

Baten³

et al. 2008

Journal of Catalysis

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A critical review of the adsorption and catalysis of n-and methylalkanes demonstrates that the interior surface of TON-and MTT-type zeolites dominates both adsorption and catalysis, and that the contribution from the exterior surface is negligible. For both n-and methylalkane isomers, the experimental Henry constants at the interior TON-type zeolite surface are more than an order of magnitude greater than those at the exterior surface. Molecular simulations on exclusively interior TON-type silica surface reproduce the adsorption isotherms of n-and methylalkane isomers remarkably well and suggest that even an isomer as bulky as 2,3-dimethylpentane could have access to the interior TON-type zeolite surface. Only the reference state used in solution thermodynamics affords an equitable comparison between internal and external surface thermodynamics. It indicates that methylalkanes adsorb in a structured fashion at the exterior TON-type zeolite surface when the interior surface is inaccessible. But the entropic penalty for this organized exterior surface "pore mouth" or "key-lock" adsorption is high, so that methylalkanes prefer adsorption at the interior surface when it is accessible. We speculate that CHA-and ERI-type sieves exhibit exterior surface catalysis in long n-alkane conversion, but the database remains too small to allow investigation of the full potential of shape selectivity in exterior zeolite surface catalysis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shape-selective n-alkane hydroconversion at exterior zeolite surfaces

Maesen

Krishna²,

Baten³

et al. 2008

Journal of Catalysis

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“…Long alkanes are then converted preferentially from their mixtures with shorter alkanes. In the hysomer process [3], the mixture of C5 and C6 straight alkane molecules is branched using bifunctional mordenite catalysts. In the present processes, extending the feed fraction to include C7 and C8 n-alkanes is not possible, since at reaction severity needed to convert C5 and C6, there is a too high conversion of C7 and C8 giving rise to undesired cracking of these molecules into gaseous compounds.…”

Section: Introductionmentioning

confidence: 99%

High-pressure liquid phase hydroconversion of heptane/nonane mixtures on Pt/H-Y zeolite catalyst

Denayer

2003

Journal of Catalysis

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The competitive hydroconversion of heptane and nonane molecules in their mixture was studied in a continuous flow, fixed-bed reactor filled with Pt/HY zeolite catalyst. Liquid-phase reaction conditions were established at reaction temperatures of 230, 250, and 270 • C by pressurizing the reactor at 100 bar. Hydrogen was supplied in an absorbed state with the liquid hydrocarbon feed. Under these liquidphase reaction conditions, the apparent reaction rates of heptane and nonane were almost identical. In a similar experiment under vaporphase conditions, nonane was much more reactive than heptane. The conversion data under liquid-phase conditions were analyzed with an adsorption-reaction model based on intrinsic kinetic parameters obtained from vapor-phase experiments. The model revealed that the enhanced reactivity of heptane in the liquid phase was due to its preferential adsorption. Simulation of the adsorption of the heptane/nonane mixture in the pores of zeolite Y with the configurational-bias Monte Carlo method confirmed the preferential adsorption of heptane in zeolite Y at high pressure. Under such conditions, in zeolite Y supercages the packing of the smaller heptane molecules is more favorable than that of the larger nonane molecules.

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“…Protonated zeolites are the principle component of cracking catalysts [5] and can be prepared by the treatment of the zeolite with strong acids. However, many crystalline zeolites decompose when treated with strong acids, so this method is only effective for high-silica zeolites [6].…”

Section: Introductionmentioning

confidence: 99%

Electrochemically controlled ion exchange: proton ion exchange with sodium zeolite X and A

Stephenson

Attfield

Holmes

et al. 2015

J Solid State Electrochem

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Structural characterisation of proton-exchanged zeolites, prepared using ion-transfer at the liquid-liquid interface, is reported. Specifically, electrochemical exchange of protons for sodium with zeolites X and A is described: the structural integrity of the resultant materials was probed by solid-state NMR spectroscopy and temperature-dependent powder X-ray diffraction. It is shown that replacement of ca. 40 % of the Na + can be achieved using this approach for both zeolites; however, the results indicate that exchange is accompanied by significant structural degradation in the case of zeolite A, with proton exchange occurring at the amorphous regions of the sample. In contrast, zeolite X retains its structure, and the level of proton exchange is comparable with the highest levels reported using conventional chemical methods, highlighting the utility of the electrochemical approach.

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Chapter 17 Hydrocarbon processing with zeolites

Cited by 67 publications

References 63 publications

Shape-selective n-alkane hydroconversion at exterior zeolite surfaces

Shape-selective n-alkane hydroconversion at exterior zeolite surfaces

High-pressure liquid phase hydroconversion of heptane/nonane mixtures on Pt/H-Y zeolite catalyst

Electrochemically controlled ion exchange: proton ion exchange with sodium zeolite X and A

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