Generation of subnanometric platinum with high stability during transformation of a 2D zeolite into 3D

Abstract

Single metal atoms and metal clusters have attracted much attention thanks to their advantageous capabilities as heterogeneous catalysts. However, the generation of stable single atoms and clusters on a solid support is still challenging. Herein, we report a new strategy for the generation of single Pt atoms and Pt clusters with exceptionally high thermal stability, formed within purely siliceous MCM-22 during the growth of a two-dimensional zeolite into three dimensions. These subnanometric Pt species are stabilized by MCM-22, even after treatment in air up to 540 °C. Furthermore, these stable Pt species confined within internal framework cavities show size-selective catalysis for the hydrogenation of alkenes. High-temperature oxidation-reduction treatments result in the growth of encapsulated Pt species to small nanoparticles in the approximate size range of 1 to 2 nm. The stability and catalytic activity of encapsulated Pt species is also reflected in the dehydrogenation of propane to propylene.

Controllable cyanation of carbon-hydrogen bonds by zeolite crystals over manganese oxide catalyst

“…Meanwhile, it is worth noting that the zeolite sheath with micropores might offer a good opportunity for achieving shape-selective catalysis, which is a crucial and an important advantage for heterogeneous catalysts4243444546. To approve this hypothesis, we performed the oxidative cyanation of a mixture of toluene and 1,3,5-trimethylbenzene.…”

Building Zeolites from Precrystallized Units: Nanoscale Architecture

“…[101] By grafting titanocene onto ITQ-2, Corma et al succeeded in preparing Ti-containing ITQ-2 as ac atalyst for the epoxidation of alkenes.T he material showed high conversion of the bulky substrate cyclohexene together with ahigh yield of the target epoxide. [103] Thea ctivity of this catalyst is nearly six times higher than normal Pt loaded by impregnation and was stable against frequent reaction-regeneration cycles at high temperature.The small cluster size,high activity,and stability is due to the spatial confinement of the MWW framework as aresult of layer engineering. [103] Thea ctivity of this catalyst is nearly six times higher than normal Pt loaded by impregnation and was stable against frequent reaction-regeneration cycles at high temperature.The small cluster size,high activity,and stability is due to the spatial confinement of the MWW framework as aresult of layer engineering.…”

Directing Reaction Pathways through Controlled Reactant Binding at Pd–TiO2 Interfaces

“…[4][5][6][7][8] Thei mportance of interfacial sites in catalysis suggests that catalyst design should emphasize novel methods for tailoring these interfaces that go beyond using the oxide as as imple catalyst carrier. While encapsulated structures have been applied to enhance the stability of metal NPs [11][12][13][14] or improve the selectivity and/or activity for selective oxidation, [15][16][17] hydrogenation, [18][19][20] and decarbonylation, [21] HDO provides an important probe reaction for testing their utility for reactions that occur at metal/oxide interfaces.M oreover,t he unique geometry of the sites in an encapsulated structure could result in an ew way to control interfacial properties via biasing the reactant binding orientations.F or aromatic alcohols,flat-lying adsorbates are prone to decarbonylation and ring hydrogenation while upright adsorption geometries favor HDO. While encapsulated structures have been applied to enhance the stability of metal NPs [11][12][13][14] or improve the selectivity and/or activity for selective oxidation, [15][16][17] hydrogenation, [18][19][20] and decarbonylation, [21] HDO provides an important probe reaction for testing their utility for reactions that occur at metal/oxide interfaces.M oreover,t he unique geometry of the sites in an encapsulated structure could result in an ew way to control interfacial properties via biasing the reactant binding orientations.F or aromatic alcohols,flat-lying adsorbates are prone to decarbonylation and ring hydrogenation while upright adsorption geometries favor HDO.…”