Nickel/USY Catalyst Derived from a Layered Double Hydroxide/Zeolite Hybrid Structure with a High Hydrogenation Efficiency

Abstract

It is important and challenging in heterogeneous catalysis to prepare catalysts with highly dispersed metal nanoparticles that have a high activity. Herein, a new Ni/USY catalyst derived from a core–shell NiAl‐LDHs/USY hybrid material has been prepared by the in situ growth of a layered double hydroxides (LDHs) precursor on the surface of USY zeolite crystals. Under the appropriate conditions, the adscititious Ni source interacted chemoselectively with Al species dissolved from the zeolite framework to form a LDHs structure anchored robustly on the surface of zeolite crystals. The dealumination of the low‐silica zeolite and the immobilization of Ni metal species were realized simultaneously in this one‐pot synthesis to afford hierarchical NiAl‐LDHs/USY hybrid composites. The NiII species in these hybrid composites were reduced readily at much lower temperatures than that of bulk NiAl‐LDH, which gave rise to highly dispersed Ni nanoparticles. Meanwhile, the resultant material possessed an excellent mesoporous structure and a high surface area inherited from the USY structure, which led to an excellent hydrogenation rate and activity for the conversion of m‐nitroaniline to m‐phenylenediamine. This unique method could be a promising and general strategy to fabricate desirable hybrid materials for redox catalysis in particular for supported transition metals with similar characteristics to Ni.

Deoxygenation of Stearic Acid over Cobalt-Based NaX Zeolite Catalysts

“…Finally, (iii) has proven challenging as hydrogen is required for the saturation of unsaturated fatty acids, leading to attempts to produce in-situ hydrogen from solvents or from sacrificial reactions [11,12]. Recent work has attempted to tackle these concerns by introducing bifunctional catalysts which provide both hydrogenation activity and solid acid activity [13][14][15][16][17][18]. Zeolites offer highly desirable properties such as high surface areas, good chemical and thermal stability, and strong acidity as a support material for metals [19].…”

Controllably Confined ZnO on USY Zeolites (USY@ZnO/Al2O3) as Efficient Lewis Acid Catalysts for Baeyer–Villiger Oxidation

“…Supporting the LDHs phase on as uitable substrate could effectively maintain the layered structure and guarantee the exposure of active sites. [22] On the basis of previous findings, herein we disclose a unique USY@ZnO/Al 2 O 3 catalyst derived from aU SY@ZnAl-LDHs core-shell precursor.T he in situ growth process of USY@ZnAl-LDHs was investigated in detail by varying the synthesis temperature, pH value, Zn source, and ammonium source.A na dvanced and thorough characterizationw as employed to determinet he nature of the ZnAl-LDHs structure and variation in the coordination state of aluminum during the whole synthetic process. Then Zhao et al obtaineda ne venly dispersed ZnAl mixed-metal oxide on an Al 2 O 3 support by using al egumeb iotemplate, whiche xhibited higherp hotocatalytic activity than the corresponding metal oxide powder sample.…”

“…Upon reduction,t he resultant Ni/USY catalyst, with highly dispersed Ni nanoparticles precisely confined on the Al 2 O 3 matrix, possessed as lightly decreased surfacea rea and pore volume, which prevented the aggregation of Ni nanoparticles during thermalt reatment and guaranteed the sufficient exposure of active sites in the hydrogenation reaction. [22] On the basis of previous findings, herein we disclose a unique USY@ZnO/Al 2 O 3 catalyst derived from aU SY@ZnAl-LDHs core-shell precursor.T he in situ growth process of USY@ZnAl-LDHs was investigated in detail by varying the synthesis temperature, pH value, Zn source, and ammonium source.A na dvanced and thorough characterizationw as employed to determinet he nature of the ZnAl-LDHs structure and variation in the coordination state of aluminum during the whole synthetic process. The catalytic activity of the resultant USY@ZnO/Al 2 O 3 catalyst was then evaluated in Baeyer-Villiger (B-V) oxidation reactions with H 2 O 2 or tert-butyl hydroxide (TBHP) as the oxidant.…”

Freestanding Cobalt‐Aluminum Oxides on USY Zeolite as an Efficient Catalyst for Selective Catalytic Reduction of NOx

“…However, the isolated LDHs precursors are prone to suffer serious aggregation by ab ‐face stacking upon calcination, highly lowering the accessibility to the active centers in the resultant aggregated bulk multiple oxides ,. Previously, we found that the Al 3+ species in Al‐rich USY zeolite themselves could participate in the fabrication of NiAl‐LDHs structure, bridging the connection between zeolite crystal and LDHs phase . The as‐fabricated Ni/USY catalyst upon reduction possessed well‐preserved hierarchical porosity of USY zeolite with sufficient exposure of highly dispersed confined Ni nanoparticles on Al 2 O 3 matrix, which thereby exhibited remarkably enhanced hydrogenation activity for the hydrogenation of nitro aromatics.…”