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Porous aromatic framework 1 (PAF‐1) is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area. Currently, the synthesis of PAF‐1 is catalyzed by the Ni(COD)2/COD/bpy system, suffering from great instability and high cost. Herein, we developed an in situ reduction of the Ni(II) catalytic system to synthesize PAF‐1 in low cost and high yield. The active Ni(0) species produced from the NiCl2/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4‐bromophenyl)methane at the room temperature to form PAF‐1 with high Brunauer–Emmett–Teller (BET)‐specific surface area up to 4948 m2 g−1 (Langmuir surface area, 6785 m2 g−1). The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail. The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs' synthesis. This work provides a cheap, facile, and efficient method for scalable synthesis of PAFs and explores their application for high‐pressure storage of Xe and Kr. [ABSTRACT FROM AUTHOR]

Activation of O2 is a critical step in heterogeneous catalytic oxidation. Here, the concept of increased electron donors induced by nitrogen vacancy is adopted to propose an efficient strategy to develop highly active and stable catalysts for molecular O2 activation. Carbon nitride with nitrogen vacancies is prepared to serve as a support as well as electron sink to construct a synergistic catalyst with Pt nanoparticles. Extensive characterizations combined with the first-principles calculations reveal that nitrogen vacancies with excess electrons could effectively stabilize metallic Pt nanoparticles by strong p-d coupling. The Pt atoms and the dangling carbon atoms surround the vacancy can synergistically donate electrons to the antibonding orbital of the adsorbed O2. This synergistic catalyst shows great enhancement of catalytic performance and durability in toluene oxidation. The introduction of electron-rich non-oxide substrate is an innovative strategy to develop active Pt-based oxidation catalysts, which could be conceivably extended to a variety of metal-based catalysts for catalytic oxidation. Activation of O2 is a critical step in heterogeneous catalytic oxidation. Here, the authors adopt the concept of increased electron donors induced by nitrogen vacancy to develop an efficient strategy for preparing highly active and stable catalysts for molecular O2 activation. [ABSTRACT FROM AUTHOR]

The Pd/Al 2 O 3 catalyst was prepared by the impregnation method to investigate the deactivation and mechanism of coke formation on metal catalysts for the selective hydrogenation of benzonitrile in a continuous fixed-bed reactor under mild conditions. The Pd/Al 2 O 3 catalyst exhibited the initial benzonitrile conversion of ∼100% with a high benzylamine selectivity of ∼86%, and continuous deactivation during the long-term reaction period of ∼1500 h. The comparative investigation of the Pd/Al 2 O 3 catalysts before and after the benzonitrile hydrogenation demonstrated that the deactivation of the Pd/Al 2 O 3 was mainly attributed to carbonaceous compounds deposited on the catalyst. The carbonaceous species contained the aromatic ring conjugated with C N double bond and tertiary amine groups, which were chemically bound onto the surface of Pd particles, leading to the irreversible loss of metallic active sites. Moreover, the carbon deposition also resulted in partial blockage of the support pores. This study is helpful to understand the deactivation and formation mechanism of carbonaceous compounds on the surface of metal catalysts for the hydrogenation reaction. [ABSTRACT FROM AUTHOR]

• Supported ZnO catalysts were obtained by using nitrogen-doped carbon (NCM) as support. • NCM contains abundant mesopores, oxygen- and nitrogen-containing functional groups. • ZnO species are highly dispersed on NCM support through metal-support interaction. • ZnO/NCM is efficient catalyst for transesterification synthesis of ethyl methyl carbonate. • Surface Zn2+ and basic sties in NCM play synergistic role in transesterification reaction. Nitrogen-doped carbon material (NCM) supported ZnO catalysts were prepared by wet impregnation method, following a high-temperature thermal treatment process. The resultant ZnO/NCM catalysts calcined at different temperatures were characterized by X-ray diffraction (XRD), Raman spectroscopy, N 2 adsorption–desorption, elemental analysis, X-ray photoelectron spectroscopy (XPS) to investigate their physicochemical properties and the interaction between ZnO and NCM support. Their catalytic properties were studied by liquid phase transesterification of dimethyl carbonate (DMC) with diethyl carbonate (DEC). Of these the catalyst calcined at 800 °C, named ZnO/NCM-800 exhibits the highest catalytic activity, as well as excellent stability and recyclability for the synthesis of ethyl methyl carbonate (EMC). The NCM support possesses abundant mesopores, rich surface oxygen-containing and nitrogen-containing functional groups, which are beneficial to build relatively strong interaction between ZnO nanoparticles and the NCM support, resulting in the generation of a highly active and stable acidic-basic bifunctional catalyst for the transesterification of DMC with DEC. [ABSTRACT FROM AUTHOR]

Polyacrylonitrile (PAN) beads supported Pd nanoparticles (NPs) exhibit excellent catalytic performance for aqueous-phase formic acid (FA) dehydrogenation. Doping suitable content of Co or Fe species could further enhance the catalytic activity of the PAN supported Pd-based NPs catalysts. Abundant CN groups existed on the surface of PAN beads are beneficial to immobilizing Pd NPs, and may also act as proton scavengers to provide a suitable basic environment for activating FA molecular. Notably, the composition-optimized catalysts can also efficiently reduce the low concentration of organic dyes (methylene blue and rhodamine B) using FA as hydrogen source under ambient conditions. [ABSTRACT FROM AUTHOR]

Various phase alumina supports were prepared by heating commercial pseudoboehmite at 400 °C and 1200 °C to obtain gamma (γ) and alpha (α) Al 2 O 3 , and by calcinations of synthetic bayerite at 400 °C and 1000 °C to obtain Eta (η) and theta (θ) Al 2 O 3 . These supports were then impregnated and calcined to prepare 0.5 wt% Pd catalysts. The prepared catalysts were characterized by XRD, BET, NH 3 –TPD, CO–TPD, H 2 –TPR, etc., and their catalytic performances were evaluated for selective hydrogenation of benzonitrile. In the order of Pd/γ-Al 2 O 3 , Pd/η-Al 2 O 3 , Pd/θ-Al 2 O 3 and Pd/α-Al 2 O 3 , the surface areas decreased from 265 to 3.8 m 2 /g, the number of acidic sites was decreased, especially for strong acid sites, and meanwhile, the Pd size increased from 3.0 to 36.9 nm. The benzonitrile conversion showed limited relationship with the nature of catalysts and assumed to rely on the H 2 transmission rate. The dibenzylamine formation was considered to be a result of competitive reactions and performed as a function of the metal dispersion. Among the four Pd/Al 2 O 3 catalysts, the Pd/γ-Al 2 O 3 and Pd/η-Al 2 O 3 both exhibited excellent stability and catalytic performance with a high benzylamine yield of ca. 90%. [ABSTRACT FROM AUTHOR]

Highlights: [•] The preparation method could affect structure and properties of iron oxide supports and then further influence the activities of supported Pt catalysts. [•] The catalyst prepared by colloid deposition method (Pt/Fe2O3-CD) exhibits high catalytic activity for the low-temperature oxidation of HCHO. [•] Suitable interaction between Pt nanoparticles and iron oxide support play a crucial role in the oxygen activation at ambient temperature. [ABSTRACT FROM AUTHOR]

Modulation of the porosity and acidity of zeolites is a very attractive subject for designing highly efficient solid-acid catalysts. In this work, Beta nanozeolite aggregates with hierarchical porous structure were synthesized via steam-assisted conversion (SAC) of dry gel in presence of seeds and a cationic polymer of polydiallyldimethylammonium chloride (PDAD). The influence of various synthesis parameters, such as the alkalinity, the contents of PDAD and zeolite seeds, and the crystallization conditions (temperature, water/dry gel ratio and time) on the formation of Beta zeolites was studied by combining a variety of characterization techniques. The SAC-synthesized Beta zeolites (S-Beta) are assembled from ultra-small nanocrystals around 10 nm to form self-sustaining micron-sized zeolitic aggregates, and possess abundant interconnected mesopores and relatively mild acidity. Compared with the conventional Beta zeolite, S-Beta aggregates show much higher catalytic activity for the Friedel-Crafts acylation of anisole with acetic anhydride. The excellent catalytic performance of S-Beta should be mainly attributed to the enhanced mass transport ability for reagents as well as the mild acidity that can avoid the rapid deactivation of the catalyst under the test conditions. [Display omitted] • Hierarchical Beta nanozeolite aggregates were synthesized by steam-assisted conversion. • Polydiallyldimethylammonium chloride and zeolite seeds were employed for the synthesis. • Beta aggregates are assembled from ultra-small nanocrystals and possesses mild acidity. • Beta aggregates exhibit higher catalytic activity for Friedel-Crafts acylation of anisole. [ABSTRACT FROM AUTHOR]

A common nonionic surfactant of Triton X-100 (TX) was used as an additive in the hydrothermal synthesis of Beta zeolites (Beta- n TX, n represents the molar ratio of TX/SiO 2). The effect of the addition amount of TX on the crystallization process of Beta zeolites was investigated by combining a variety of characterization means. Introducing a small amount of TX (e.g., n = 0.005) in the initial sol-gel system could considerably shorten the induction period of crystallization, thus effectively improving the crystallization rate of Beta zeolites. Moreover, the crystal size of the resultant Beta zeolites decreases obviously after introducing the TX additive. The H-form Beta- n TX zeolites showed much higher catalytic activity in the acylation of anisole with acetic anhydride than the conventional Beta zeolite. Their excellent catalytic performance should be mainly related to the relatively small particle size and high crystallinity of Beta- n TX zeolites, which can reduce the diffusion limitation and improve the accessibility of catalytically active acid sites to reagents. [Display omitted] • Beta zeolites were hydrothermally synthesized by introducing Triton X-100 additive. • Triton X-100 may act as emulsifier to influence the nucleation and growth of zeolite. • Adding small amount of Triton X-100 can shorten the induction period of crystallization. • Highly crystallized Beta zeolite with small size can be obtained within 24 h. • Triton X-100 mediated H-form Beta catalysts exhibit enhanced activity for acylation reaction. [ABSTRACT FROM AUTHOR]

Abstract: A series of nitrogen-doped nanoporous carbon (NNC) materials were prepared by directly carbonizing sol–gel composites containing aluminum phosphate, citric acid and hexamethylene tetramine (HMT). The structure and surface properties of these NNC materials were characterized by means of elemental analysis, N2 adsorption, X-ray powder diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), and X-ray photoelectron spectra (XPS). Besides possessing various oxygen-containing groups, these NNC materials also contain different types of nitrogen-containing groups, including pyridinic-N, pyrrolic-N and quaternary-N groups. The resulting NNC materials are highly active and selective heterogeneous catalysts for the transesterification of dimethyl oxalate (DMO) with phenol to produce methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), and can be easily recycled by simple filtration. The presence of suitable surface basic sites should be mainly responsible for the excellent catalytic performance of NNC materials in the transesterification reaction. [Copyright &y& Elsevier]

Abstract: The acid properties of MCM-49 zeolites were modified by phosphonic acid via a simple impregnation method. The physicochemical properties of the samples were well characterized by XRD, NH3-TPD, FT-IR of d 3-acetonitrile adsorption, 27Al MAS NMR, and their activity in the skeletal isomerization of n-butene was measured as well. It was found that the concentrations of Brønsted and Lewis acid sites have been markedly reduced by the phosphonic acid impregnation. The catalytic results indicated that Brønsted acid sites were active sites for the skeletal isomerization of n-butene, while Lewis acid sites almost had no effect. [Copyright &y& Elsevier]

Abstract: Ammonium metatungstate (AMT) impregnated SiO2, TiO2 and Al2O3 catalysts were found to be highly active and selective for the vapour-phase O-methylation of catechol with methanol. Particularly, the AMT/SiO2 catalyst with 7.9wt% W content showed the highest catechol conversion (97.1%) and the highest guaiacol yield (88.1%). [Copyright &y& Elsevier]

Abstract: Au/MeCO3 (Me=Ca, Sr, Ba) catalysts prepared by co-precipitation method were studied for low-temperature CO oxidation in the presence/absence of water in the feed stream. The type of support and the calcination temperatures have considerable effect on the activity of the catalysts. Among them, Au/BaCO3 calcined at 473 K shows the highest activity, full conversion of CO can be obtained at ambient reaction temperature in the presence of moisture. The addition of water vapor in feed stream has positive influence on the activity of Au/MeCO3 catalysts for CO oxidation, which might be due to water can participate CO oxidation reaction directly. [Copyright &y& Elsevier]