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

Abstract

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.

Selective steam reforming of n‐dodecane over stable subnanometric NiPt clusters encapsulated in Silicalite‐1 zeolite

“…Zeolite materials were deemed as idea supports to confine metal particles, owing to the diverse porosities, controllable synthesis process, and large surface areas . The encapsulating Ni NPs in mesoporous zeolites, thus enhancing sintering resistance, has been reported by several groups . For example, Gong et al designed a nickel phyllosilicate nanotubes catalyst for ethanol steam reforming, which showed high thermal stability of nickel nanoparticles at 650°C due to the confinement effect of phyllosilicate nanotubes, thus improving the stability and inhibiting carbon deposition .…”

Synergy Effects of Cobalt Oxides on Ni/Co-Embedded Al2O3 for Hydrogen-Rich Syngas Production by Steam Reforming of Propane

“…Moreover, the facile aggregations of Ni metals, which lead to their transformations to the less active solid-solutions such as nickel aluminates, induce lower stability of the Ni-based catalysts [12,13]. The Ni-based reforming catalysts can be modified to lessen these problems by following general methodologies: to keep the small sizes of nickel nanoparticles [14][15][16][17] for better dispersion and less aggregation, to modify the supports via addition of alkali metals, lanthanides and rare earth metals [5,[18][19][20][21][22], to decrease carbon deposition with a help of basicity of those promoters and to add a small amount of noble metals such as Ru and Rh to promote the in-situ reducibility of the Ni species through various synthetic methods [9,23]. Interestingly, compared to the monometallic Ni or Co-based catalysts, bimetallic catalysts using Ni and Co species simultaneously were reported to enhance the catalytic performances as well as produce less coke formations in various reforming processes [12,[24][25][26].…”

Designing Nanoparticles and Nanoalloys for Gas-Phase Catalysis with Controlled Surface Reactivity Using Colloidal Synthesis and Atomic Layer Deposition

“…In that regard, "embedding" the colloidal NPs within a support proves an interesting solution. By encasing the particles, their mobility is restricted, such that sintering-induced deactivation is mitigated [162]. The support's porosity, created by thermal and/or chemical treatments [163][164][165], ensures the mass transfer of reagents and products.…”