Incorporating metal nanoparticles in porous materials via selective heating effect using microwave

Metal nanoparticle@porous material composites have attracted increasing attention due to their excellent synergistic catalytic performance.However,it is a challenge to introduce metal nanoparticles into cavities of porous materials without agglomeration on the exterior.Despite the progress achieved,a universal approach that can integrate different kinds of metal nanoparticles and porous materials is still highly desirable.Here we report a facile and general approach to fabricating metal nanoparticle@porous materials by microwave-triggered selective heating.The microwave can pass through the non-polar solvent and act on the polar solvent in the porous materials,causing the polar solvent to be heated,vaporized,and away from the pores of porous materials.The local void produced by the escape of polar solvent facilitates non-polar solvent containing metallic precursor to be dragged into the narrow pores,followed by further reduction,resulting in the complete encapsulation of nanoparticles.A series of metal nanoparticles@porous materials,ranging from metal-organic frameworks(MOFs)to zeolites,are successfully prepared by this method and show excellent size selectivity in catalytic reactions.

Plasmonic coupling-enhanced in situ photothermal nanoreactor with shape selective catalysis for C–C coupling reaction

Carbon-carbon(C–C)coupling reactions represent one of the most powerful tools for the synthesis of complex natural products,bioactive molecules developed as drugs and agrochemicals.In this work,a multifunctional nanoreactor for C–C coupling reaction was successfully fabricated via encapsulating the core-shell Cu@Ni nanocubes into ZIF-8(Cu@Ni@ZIF-8).In this nanoreactor,Ni shell of the core-shell Cu@Ni nanocubes was the catalytical active center,and Cu core was in situ heating source for the catalyst by absorbing the visible light.Moreover,benefiting from the plasmonic resonance effect between Cu@Ni nanocubes encapsulated in ZIF-8,the absorption range of nanoreactor was widened and the utilization rate of visible light was enhanced.Most importantly,the microporous structure of ZIF-8 provided shape-selective of reactant.This composite was used for the highly shape-selective and stable photocatalysed C–C coupling reaction of boric acid under visible light irradiation.After five cycles,the nanoreactor still remained high catalytical activity.This Cu@Ni@ZIF-8 nanoreactor opens a way for photocatalytic C–C coupling reactions with shape-selectivity.

Shape selective catalysis in methylation of toluene： Development, challenges and perspectives

Toluene methylation with methanol offers an alternative method to produce p-xylene by gathering methyl group directly from C1 chemical sources. It supplies a ＂molecular engineering＂ process to realize directional conversion of toluene/methanol molecules by selective catalysis in complicated methylation system. In this review, we introduce the synthesis method ofp-xylene, the development history of methylation catalysts and reaction mechanism, and the effect of reaction condition in para-selective technical process. If constructing p-xylene as the single target product, the major challenge to develop para-selective toluene methylation is to improve the p-xylene selectivity without, or as little as possible, losing the fraction of methanol for methylation. To reach higher yield ofp-xylene and more methanol usage in methylation, zeolite catalyst design should consider improving mass transfer and afterwards coveting external acid sites by surface modification to get short ＂micro-tunnels＂ with shape selectivity. A solid understanding of mass transfer will benefit realizing the aim of converting more methanol feedstock into para-methyl group.

A new breakthrough in selective catalysis: metal-organic framework nanocomposites with sandwich structure

Selective hydrogenation of C=O group that is conjugated with a C=C group in a,b-unsaturated aldehydes(R–CH=CH–CHO)is one of important reactions in industry due to the resulting product unsaturated alcohols(R–CH=CH–CH2OH)with broad applications in synthesis of fine chemicals such as flavour,fragrance,pharmaceuticals[1].However,despite the increasing reported catalysts on the selectivity[2,3],developing an effective

Regulating Electronic Status of Platinum Nanoparticles by Metal-Organic Frameworks for Selective Catalysis

Selective hydrogenation of alkynes to alkenes remains challenging in the field of catalysis due to the ease of over-hydrogenated of alkynes to alkanes.Favorably,the incorporation of metal nanoparticles(MNPs)into metal-organic frameworks(MOFs)provides an opportunity to adjust the surface electronic properties of MNPs for selective hydrogenation of alkynes.Herein,we used differentmetal-O clusters of MOFs to regulate the electronic status of platinum nanoparticles(Pt NPs)toward overhydrogenation,semihydrogenation,and unhydrogenation of phenylacetylene.Specifically,Pt/Fe-O cluster-based MOFs are found to reduce the electronic density on Pt NPs and inhibit the overhydrogenation of styrene,leading to an 80%increase in selectivity toward a semihydrogenation product(styrene).Meanwhile,Cu-O cluster-based MOFs generate high oxidation states of Pt NPs and release Cu^(2+)ions,which worked together to deactivate Pt NPs in the hydrogenation reaction entirely.Thus,our studies illustrate the critical role of metal-O clusters in governing chemical environments within MOFs for the precise control of selective hydrogenation of alkynes,thereby,offering appealing opportunities for designing MNPs/MOFs catalysts to prompt a variety of reactions.

Synergetic catalysis of ceria and titania for selective reduction of NO

The promotional effect of the interaction between titania and ceria on the catalytic performance for selective reduction of NO was studied.The catalysts,CeO 2,TiO 2,CeO 2 /TiO 2 and Ti x Ce 1-x O 2,were synthesized and tested in NH 3-Selective catalytic reduction（SCR） of NO,and the samples were characterized by the Brunaller,Emmett and Teller（BET absorbed gas N 2）,X-ray diffraction（XRD）,high resolution transmission electron microscopy（HR-TEM）,and temperature programmed desorption（TPD NH 3） techniques.The improvement mechanism of the interaction between the titania and ceria had been explored and discussed from two aspects of micro-structure and surface acidity.The interaction between the titania and ceria greatly improved the catalytic activity but had little effect on the active temperature.It was first reported that the acid amount determined the catalytic activity and the acid strength determined the active temperature for NH 3-SCR of NO.

Nanoparticles@nanoscale metal-organic framework composites as highly efficient heterogeneous catalysts for size-and shape-selective reactions

Composites incorporating nanoparticles （NPs） within metal-organic frameworks （MOFs） find applications in many different fields.In particular,using MOF layers as molecular sieves built on the NPs could enable selectivity in heterogeneous catalysis.However,such composites typically exhibit low catalytic efficiency,due to the slow diffusion of the reactants in the long and narrow channels of the MOF shell.In order to improve the catalytic efficiency of these systems,here we report the fabrication of NPs incorporated in nanosized MOFs （NPs@nano-MOFs）,obtained by reducing the size of the MOF crystals grown around the NPs.The crystal size of the composites was controlled by modulating the nucleation rate of the MOFs during the encapsulation of pre-synthesized and catalytically active NPs;in this way,NPs@MOF crystals smaller than 50 nm were synthesized and subsequently used as highly efficient catalysts.Due to the shorter path from the MOF surface to the active sites,the obtained Pt@nano-MOFs composites showed a higher conversion rate than their larger-sized counterparts in the synthesis of imines via cascade reaction of nitrobenzene and in the hydrogenation of olefins,while retaining the excellent size and shape selectivity associated with the molecular sieving effect of the MOF layer.The present strategy can also be applied to prepare other encapsulated nanostructures combining various types of NPs and nano-MOFs,thus highlighting the broad potential of this approach for developing optimized catalysts with high reactivity and selectivity.

Precise Synthesis of Hollow Mesoporous Palladium–Sulfur Alloy Nanoparticles for Selective Catalytic Hydrogenation

Hollow mesoporous metals have unique potential for catalysis,but their precise synthesis and further elaboration of their structure–performance relationships are still huge challenges.Herein,wereport a new synthetic strategy,named the Kirkendall effect in synergistic template(KEST),for the desired preparation of hollow mesoporous palladium–sulfur(h-mesoPdS)alloy nanoparticles.

Tf_2NH-catalyzed,highly regio-and stereo-selective synthesis of trisubstituted alkenes and indane derivatives from benzylic alcohols and alkenes

A reaction of benzylic alcohols with alkenes has been developed in the presence of bis（trifluoromethane）sulfonimide for the synthesis of trisubstituted alkenes and indane derivatives with high stereoselectivity.In general,benzylic alcohols react with 1,1-diaryl alkenes to afford trisubstituted alkenes,and the reaction with 1,2-disubstituted and trisubstituted alkenes affords indane derivatives through a [3 ＋ 2] annulation reaction.