Molecular-size selective H-β zeolite-encapsulated Ce-Zr/Ni-Mg catalysts for steam reforming

Cimenler, Ummuhan; Joseph, Babu; Kuhn, John N.

doi:10.1016/j.apcata.2015.05.014

Cited by 22 publications

(29 citation statements)

References 40 publications

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“…H‐β‐zeolite‐encapsulated Ni−Mg/Ce 0.6 Zr 0.4 O 2 core shell catalysts have been synthesized by double physical coating strategy for SRT and SRM reaction ,. The effect of H‐β‐zeolite shell thickness to the activity and selectivity has been systematically studied.…”

Section: Applications Of Core/yolk Shell Catalysts For Hydrocarbon Rementioning

confidence: 99%

“…The effect of H‐β‐zeolite shell thickness to the activity and selectivity has been systematically studied. It was found that the H‐β‐zeolite shell coating had an opposite effect to CH 4 and toluene conversion respectively with the former increased after shell coating due to the intermediate pore size of the shell compared with these two molecules, showing size selectivity of the core shell catalysts for SRT and SRM reaction respectively . Further increase of shell thickness (when the content of zeolite raised from 34.3 wt % to 51 wt %) will lead to the decrease of conversions for both these two molecules due to the mass transfer limitation .…”

Section: Applications Of Core/yolk Shell Catalysts For Hydrocarbon Rementioning

confidence: 99%

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Sintering and Coke Resistant Core/Yolk Shell Catalyst for Hydrocarbon Reforming

Wang

Kawi

2018

ChemCatChem

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Syngas/hydrogen production via hydrocarbon reforming reactions is crucial. Whereas, they need high reaction temperature to obtain economically feasible hydrocarbon conversions, which renders the active and cheap transition metal based catalysts easy to be sintered, leading to the high carbon deposition rate and gradual degradation of catalytic performance. Therefore, developing sintering and carbon resistant catalysts becomes one of the most important issues for these reforming reactions to be industrially applied. Designing catalysts with core/yolk shell structure turns out to be one of the most effective strategies to solve this issue. Herein, recent progress which has been made in the synthesis method for core/yolk shell catalysts with different shell materials such as SiO2, zeolite, CeO2 and Al2O3 is summarized. Additionally, specific applications of these core/yolk catalysts for various hydrocarbon reforming reactions such as dry reforming, steam reforming and methane oxidation are reviewed with the emphasis on revealing the reasons leading to their outstanding catalytic performance. Lastly, possible research directions in core/yolk shell catalysts are proposed.

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Section: Applications Of Core/yolk Shell Catalysts For Hydrocarbon Rementioning

confidence: 99%

Section: Applications Of Core/yolk Shell Catalysts For Hydrocarbon Rementioning

confidence: 99%

Sintering and Coke Resistant Core/Yolk Shell Catalyst for Hydrocarbon Reforming

Wang

Kawi

2018

ChemCatChem

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“…It possesses pores larger than those of ZSM-5 with 12-memeberd ring openings (0.75 by 0.57 nm for linear and 0.65 by 0.56 nm for tortuous channels). BEA zeolite was tested as a support of catalytically active phases [35][36][37][38][39], including the total oxidation of VOCs [13-15, 20-21, 40]. In the latter case, a majority of research was done for noble-metal systems.…”

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confidence: 99%

Cobalt-containing BEA zeolite for catalytic combustion of toluene

Rokicińska

Drozdek

Dudek

et al. 2017

Applied Catalysis B: Environmental

104

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GRAPHICAL ABSTRACT Highlights-Controlled amounts of cobalt were homogeneously introduced in BEA structure.-Various forms of Co species were identified in Co-containing BEA structure.-After saturation of framework sites Co formed oxide clusters and crystallites.-The presence of Lewis acid sites resulted in enhanced selectivity to CO and benzene.-The highest activity showed Co-containing SiBEA with dominant contribution of Co3O4. AbstractCo-containing HAlBEA zeolite was obtained by conventional wet impregnation of HAlBEA zeolite with an aqueous Co(NO3)2 . 6 H2O solution, whereas Co-containing SiBEA zeolites were prepared by a two-step post-synthesis method. This approach consists of, in the first step, dealumination of parent BEA zeolite to obtain an aluminum-free SiBEA support and then, in the subsequent step, contact of the obtained material with an aqueous solution of cobalt nitrate. As shown by X-ray diffraction and low-temperature N2 adsorption, the dealumination of BEA zeolite and introduction of cobalt ions did not involve destruction of zeolite structure, and only insignificant blocking of pore system was observed after introduction of high amounts of cobalt. Nevertheless, clear changes in acidity were found by FTIR of pre-adsorbed pyridine after dealumination of parent BEA zeolite and introduction of cobalt ions. The presence of Lewis acid sites resulted in enhanced selectivity to CO and benzene formed as by-products in the toluene combustion. Therefore, SiBEA zeolite was chosen as a support for an introduction of various amounts of Co into the zeolite structure (the intended Co contents of 3.0 -9.0 wt %). Depended on the amount of the introduced Co, cobalt was incorporated into the framework of BEA zeolite as isolated mononuclear Co(II) species, small Co(II) oxide clusters and/or Co3O4 crystallites distributed in the whole zeolite structure.The chemical environment and dispersion of cobalt species were studied by transmission electron microscopy (TEM), FTIR of pre-adsorbed NO, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). Temperature-programmed reduction of hydrogen (H2-TPR) was also performed to determine reducibility of the Cocontaining SiBEA zeolites. It was confirmed that siliceous SiBEA zeolite was the excellent support of Co3O4, which was in turn recognized as the main active phase in the total oxidation of toluene. The best catalytic performance was achieved over the catalysts containing at least 0.05 mmol of Co in the form of Co3O4 per 1 g of SiBEA zeolite.

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“…The controlled traffic of reactants providing improved reforming selectivity was demonstrated very recently by Cimenler [242] in the steam reforming of CH4 and C7H8 where the latter represents a model for tar impurity in feed. Applying H-β zeolite membrane shell on the steam reforming Ni/Mg/Ce0.6Zr0.4O2 catalyst led to decreased C7H8 conversion compared to the uncoated catalyst exemplifying the molecular-size selective properties of the membrane.…”

Section: Application In Reactant-selective or Product-selective Reactmentioning

confidence: 99%

“…Alternatively, liquid membrane crystallization being a modified vapor transport method was proposed as economic, environmental and highly effective method for synthesis of zeolite-encapsulated catalysts [240]. Furthermore, physical coating was suggested for easy scalable synthesis where the required high temperature and alkaline conditions during hydrothermal synthesis were excluded [241][242][243]. Recently, steam-assisted crystallization process was recommended as an efficient method for capsuled catalysts preparation [244].…”

Section: Zeolite Membrane Coatings On Catalyst Particlesmentioning

confidence: 99%

Zeolite Membranes in Catalysis—From Separate Units to Particle Coatings

Dragomirova

Wohlrab

2015

Catalysts

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Literature on zeolite membranes in catalytic reactions is reviewed and categorized according to membrane location. From this perspective, the classification is as follows: (i) membranes spatially decoupled from the reaction zone; (ii) packed bed membrane reactors; (iii) catalytic membrane reactors and (iv) zeolite capsuled catalyst particles. Each of the resulting four chapters is subdivided by the kind of reactions performed. Over the whole sum of references, the advantage of zeolite membranes in catalytic reactions in terms of conversion, selectivity or yield is evident. Furthermore, zeolite membrane preparation, separation principles as well as basic considerations on membrane reactors are discussed.

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Molecular-size selective H-β zeolite-encapsulated Ce-Zr/Ni-Mg catalysts for steam reforming

Cited by 22 publications

References 40 publications

Sintering and Coke Resistant Core/Yolk Shell Catalyst for Hydrocarbon Reforming

Sintering and Coke Resistant Core/Yolk Shell Catalyst for Hydrocarbon Reforming

Cobalt-containing BEA zeolite for catalytic combustion of toluene

Zeolite Membranes in Catalysis—From Separate Units to Particle Coatings

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