Combined Diffusion, Adsorption, and Reaction Studies of n-Hexane Hydroisomerization over Pt/H–Mordenite in an Oscillating Microbalance

Donk, Sander van; Broersma, Alfred; Gijzeman, O.L.J.; Bokhoven, Jeroen A. van; Bitter, Johannes H.; Jong, Krijn P. de

doi:10.1006/jcat.2001.3393

Cited by 120 publications

(72 citation statements)

References 20 publications

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“…Although alumina supported catalysts are more active at low temperatures, they are highly sensitive to poisoning by both water and sulfur and therefore require constant regeneration with chlorine which is hazardous and can potentially alter the structure of the precious metal. Consequently, enormous research effort has focused on using the more stable and environmental-friendly zeolite-based catalysts, since they possess the necessary acidity, internal structure and pore size distribution to be catalytically active and selective for these hydroisomerizations [6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite Beta materials and on their catalytic activity for the hydroisomerization of alkanes

Roldán

Beale²,

Sánchez‐Sánchez

et al. 2008

Journal of Catalysis

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A series of mono-and bi-metallic (Pt and/or Pd) impregnated zeolite Beta samples have been prepared, characterized using a number of experimental techniques and catalytically tested for the hydroisomerization of a mixture of light paraffins. In particular, the effect of the order of Pt and Pd impregnation on the type/structure of the metallic species of the zeolite support and on the catalytic activity has been studied. Studied samples included a zeolite Beta in which both Pt and Pd (0.5 wt% of each) were simultaneously impregnated (and subsequently calcined and reduced) and two equally metal-loaded samples where the metals were sequentially impregnated (samples Pt*-Pd/Beta and Pd*-Pt/Beta, in which Pt and Pd were impregnated first, respectively). Mono-metallic samples were also prepared for comparison. TPR, DR-UV-visible, TEM, and XAS studies confirm that the order of impregnation plays a key role in the formation of metallic particles, influencing aspects as decisive in their catalytic behavior as their size, their dispersion and their composition (e.g., mono-or bi-metallic). The initial impregnation of Pd and subsequently of Pt produces a higher number of hetero-metallic (Pt-Pd) bonds than the simultaneous co-impregnation and especially for the impregnation in reverse order, which does not produce Pt-Pd bonds in a detectable amount. Based on the results from the different characterization techniques, a model of the metal distribution and composition of the particles was proposed for each bi-metallic sample. In good agreement, the order of the catalytic activity was found to be Pd*-Pt/Beta > Pd-Pt/Beta > Pt/Beta > Pt*-Pd/Beta > Pd/Beta, making clear that not only the presence of both metals, but also an adequate preparation method generating a high number of hetero-metallic bonds must be taken into account to improve the catalytic properties in relation to the mono-metallic samples.

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Section: Introductionmentioning

confidence: 99%

Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite Beta materials and on their catalytic activity for the hydroisomerization of alkanes

Roldán

Beale²,

Sánchez‐Sánchez

et al. 2008

Journal of Catalysis

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“…Since the point of view of large reactant molecules, the presence of mesoporous in the zeolite will increase the external surface and pore openings accessible to the reactant [417,418]. Mesoporous zeolites can be used for a number of industrial catalytic applications such as catalytic cracking, hydrocracking, aromatic alkylation and alkene hydroisomerization, as well as fine chemical synthesis [417,419,420].…”

Section: Catalysismentioning

confidence: 99%

Template-based syntheses for shape controlled nanostructures

Pérez-Page

et al. 2016

Advances in Colloid and Interface Science

129

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A variety of nanostructured materials are produced through template-based synthesis methods, including zerodimensional, one-dimensional, and two-dimensional structures. These span different forms such as nanoparticles, nanowires, nanotubes, nanoflakes, and nanosheets. Many physical characteristics of these materials such as the shape and size can be finely controlled through template selection and as a result, their properties as well. Reviewed here are several examples of these nanomaterials, with emphasis specifically on the templates and synthesis routes used to produce the final nanostructures. In the first section, the templates have been discussed while in the second section, their corresponding synthesis methods have been briefly reviewed, and lastly in the third section, applications of the materials themselves are highlighted. Some examples of the templates frequently encountered are organic structure directing agents, surfactants, polymers, carbon frameworks, colloidal sol-gels, inorganic frameworks, and nanoporous membranes. Synthesis methods that adopt these templates include emulsion-based routes and template-filling approaches, such as self-assembly, electrodeposition, electroless deposition, vapor deposition, and other methods including layer-by-layer and lithography. Templatebased synthesized nanomaterials are frequently encountered in select fields such as solar energy, thermoelectric materials, catalysis, biomedical applications, and magnetowetting of surfaces.

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“…An equitable comparison between the performance of MAZand MOR-type zeolites turned out to be remarkably complicated, for the accessibility [21][22][23][24][25][26][27], density, and strength [7,28,29] of the Brønsted acid sites all appear critically dependent on the zeolite synthesis [23,[30][31][32][33][34] and modification [23,35,36] processes. After nearly a decade of research, it was concluded that the improvement of MAZ-over MORtype zeolites was too small to merit commercialization of the former [29,37].…”

Section: Introductionmentioning

confidence: 99%

The selectivity of -hexane hydroconversion on MOR-, MAZ-, and FAU-type zeolites

Calero

Schenk

Dubbeldam

et al. 2004

Journal of Catalysis

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Analyses of a series of published n-hexane hydroisomerization product slates suggest that MAZ-type zeolites yield more dimethylbutane and less methylpentane than either FAU-or MOR-type zeolites. Molecular simulations do not corroborate the traditional view that these selectivity differences are specifically related to the MAZ-, FAU-, or MOR-type zeolite topology. A scrutiny of the literature indicates that reported variation in selectivity relates to a variation in the efficiency of the (de)hydrogenation function relative to the acid function. The FAU-type zeolite catalyst had the most efficient hydrogenation function. The efficiency of the hydrogenation function on the MAZ-type zeolite was low enough to significantly enhance the 2,3-dimethylbutane yield relative to the methylpentane yield, but not low enough to decrease the 2,2-dimethylbutane yield. The efficiency of the hydrogenation function on the MOR-type zeolite was low enough to do both. Only at a sufficiently high n-hexane hydroconversion does the catalyst with the most efficient hydrogenation function exhibit the highest dimethylbutane yield. This new perspective on the reported hexane hydroconversion selectivities suggests that a FAU-type zeolite catalyst with a highly efficient hydrogenation function is best suited for n-hexane hydroisomerization. The FAU topology has the highest porosity which should afford the highest activity without impairing selectivity.  2004 Elsevier Inc. All rights reserved.

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Combined Diffusion, Adsorption, and Reaction Studies of n-Hexane Hydroisomerization over Pt/H–Mordenite in an Oscillating Microbalance

Cited by 120 publications

References 20 publications

Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite Beta materials and on their catalytic activity for the hydroisomerization of alkanes

Effect of the impregnation order on the nature of metal particles of bi-functional Pt/Pd-supported zeolite Beta materials and on their catalytic activity for the hydroisomerization of alkanes

Template-based syntheses for shape controlled nanostructures

The selectivity of -hexane hydroconversion on MOR-, MAZ-, and FAU-type zeolites

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