Electromagnetic Mill-Promoted Palladium-Catalyzed Heck-Type Cyclization/Decarboxylative Coupling of (Z)-1-Iodo-1,6-diene with Propiolic Acids.

Electromagnetic mill (EMM)-promoted solid-state cascade Heck-type cyclization/decarboxylative coupling of propiolic acid with (Z)-1-iodo-1,6-diene derivate was demonstrated. The reaction was realized via palladium catalysis, which is solvent-free and involves no additional heating. The collision between ferromagnetic rods could not only be a favor to the mixing between the solid substrates and the catalyst system, but also the thermogenic action could accelerate this transformation. More importantly, this EMM strategy realized multiple bond construction under mechanochemical conditions in one pot.

Ultrasonic-pretreated hydrothermal synthesis of less dense zeolite CHA from the transformation of zeolite T.

Because of containing the same double 6-ring (D6R) building unit, the pure zeolite CHA with lower framework density (FDSi = 15.1 T/1000 Å3) has been transformed from zeolite T with higher framework density (FDSi = 16.1 T/1000 Å3) through ultrasonic-pretreated hydrothermal synthesis in MOH (KOH and NaOH) solution without adding organic template or seed crystals. Ultrasonic pretreatment facilitates the transformation rate and generates high-quality zeolite CHA. The ultrasound condition should be precisely controlled because that CHA phase is metastable, which is inclined to transform to other more stable phase. The ultrasonic conditions at 313 K and 333 K have been investigated in detail. In KOH solution, the ultrasonic treatment at 313 K can effectively restrain the generation of MER phase, however, it is hard to avoid the existence of MER phase when ultrasound temperature is 333 K. In NaOH solution, the samples with ultrasonic treatment of 313 K show the small particles size of about 1 µm, and the GIS framework topology starts to grow with the ultrasonic treatment of 333 K. The products prepared with the appropriate ultrasonic pretreatment represents smaller particles size, larger mesopore volume and higher CO2 adsorption capacity than the sample without the ultrasonic pretreatment. The structural evolution of interzeolite transformation has been explored by XRD, FT-IR and SEM observations. With the assistance of ultrasound, the parent zeolite T can quickly decompose into intermediate phase and then regenerate into CHA phase.

Cu/SiO2 synthesized with HKUST-1 as precursor: high ratio of Cu+/(Cu+ + Cu0) and rich oxygen defects for efficient catalytic hydrogenation of furfural to 2-methyl furan.

Cu/SiO2 is one of the most promising catalysts for the furfural (FF) hydrogenation reaction but suffers from the difficulty of tailoring the microstructure and surface properties. Herein, we developed a MOF-derived Cu/SiO2 catalyst (Cu/SiO2-MOF) for FF hydrogenation to 2-methyl furan (2-MF). In comparison with Cu/SiO2 catalysts prepared from ammonia evaporation (Cu/SiO2-AE) and traditional impregnation (Cu/SiO2-TI), the copper species in Cu/SiO2-MOF could not only be anchored on the silica surface via forming Cu-O-Si bonds but also exposed many more active sites. In this way, a higher ratio of Cu+/(Cu+ + Cu0) and richer oxygen defects were constructed via strong metal-support interactions, which were responsible for the superior catalytic performance. In addition, it was found that the solvent effect on product distribution played an important role in adjusting the selectivity to 2-MF and cyclopentanone (CPO). The present work not only provides a deep insight into the catalytic mechanism of Cu/SiO2-MOF for the FF hydrogenation reaction but also sheds light on the design and synthesis of highly efficient catalysts for other heterogeneous catalysis fields.

Surface-sealing encapsulation of phosphotungstic acid in microporous UiO-66 as a bifunctional catalyst for transfer hydrogenation of levulinic acid to γ-valerolactone.

The efficient production of γ-valerolactone (GVL) from renewable lignocellulose that is synthesized in plants by photosynthesis to replace the declining fossil resources conforms to the principles of circular economy. Compared to direct hydrogenation by H2 molecules, catalytic transfer hydrogenation (CTH) of levulinic acid (LA) and/or its esters to GVL with organic alcohols as a hydrogen source is a much milder route. The synergistic catalysis between Lewis and Brønsted acids is indispensable in the CTH process. Considering that unsaturated coordinated Zr species could act as Lewis acid sites and phosphotungstic acid (PTA) could dissociate protons as Brønsted acid sites, UiO-66 (Zr) was thus "acidified" by encapsulating PTA in its channels to tune the ratio of Brønsted to Lewis acid sites as a bifunctional catalyst so as to better understand the catalytic structure-performance relationship in the CTH process. To address the dilemma of encapsulated PTA that is prone to leach, a rapid surface sealing strategy was adopted to establish a polyimide (PI) coating over the surface of UiO-66 introducing a space confinement effect via an anhydride-amine coupling reaction. The as-synthesized PTA/UiO-66@PI catalyst exhibited 100% of LA conversion, a 93.2% of GVL yield and high recyclability for at least five consecutive cycles. Moreover, a reaction pathway followed by esterification, hydrogenation and dealcoholization as well as a catalytic hydrogenation mechanism based on intermolecular hydride ß-H transfer were proposed. Current work not only provides a high-performance and high-stability catalytic system to selectively produce GVL from LA or its esters, but also sheds light on the catalytic mechanism of the CTH process at the molecular level.

Enhanced metal-support interaction between Pd and hierarchical Nb2O5via oxygen defect induction to promote CO oxidative coupling to dimethyl oxalate.

Production of ethylene glycol from coal is a particularly interesting route as it is an economic alternative to the petrochemical-based route. In this process, effectively generating dimethyl oxalate (DMO) is a crucial step by CO oxidative coupling reaction under Pd-based catalysts. However, the aggregation of Pd species over the support is still an issue that relates to the deterioration of catalytic activity and stability. To this end, enhancing the metal-support interaction is urgently required. In this work, hierarchical Nb2O5 (H-Nb2O5) microspheres with abundant oxygen defects were synthesized to anchor the Pd species thus promoting the electron transfer between Pd species and Nb species associated with the generation of interfacial Pd-NbOx sites. Besides, the thinned electron density of Pd species resulting from the electron-withdrawing effect of Nb species is beneficial for activating the adsorbed CO molecules, leading to superior catalytic activity. The Pd/H-Nb2O5 catalyst exhibited 63.1% of CO conversion (theoretical maximum conversion: 64.3%) and 92.9% of DMO selectivity, with a DMO weight time yield of 1297.9 g kgcat.-1 h-1, and remained robust even after 50 h of time on stream evaluation. Current work provides a deep insight into the CO activation mechanism and helps improve the catalytic stability by boosting interfacial electron interaction via oxygen defects induction, and also sheds light on the design and synthesis of high-performance catalysts in other heterogeneous catalysis fields.

Turning Pore Size of Silica-Based Nano-TiO2 for Treating Cyanide Wastewater.

Cyanide wastewater is a very highly toxic substance. In this study, a kind of silicon-based nano-TiO2 material by turning pore size accurately is prepared to treat cyanide wastewater. The materials are characterized by XRD, TG analysis, N2 adsorption/desorption test, UVAS analysis and TEM. Results show that adding NaCl to the synthesis of silica supports can change the size of pores. It emerges that pore size can affect the catalytic performance of the material. Catalytic experiments confirm that cyanide has the best catalytic effect when it has a pore size of 16.47 nm. UVAS spectrum demonstrate that the cyanide has been broken down rather than adsorbed onto the material.

Synergistic effect of adsorptive photocatalytic oxidation and degradation mechanism of cyanides and Cu/Zn complexes over TiO2/ZSM-5 in real wastewater.

The treatment of cyanide wastewater from the gold industry is essential. Photocatalytic oxidation is an effective method for the elimination of cyanides and metal cyanide complexes. TiO2/ZSM-5 composite photocatalysts with different SiO2/Al2O3 ratios were prepared using the solid-state dispersion (SSD) method. The composite catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The catalytic efficiency of different SiO2/Al2O3 ratios and the synergistic effect of adsorptive photocatalytic oxidation for the degradation of cyanide wastewater was investigated under different adsorption and illumination times. With the extension of the photocatalytic time (>2.0 h), the composite catalyst with a high SiO2/Al2O3 ratio had better photocatalytic performance. A 93.97% degradation efficiency of total cyanides was observed after adsorption for 3.0 h and illumination for 4.0 h under room temperature with air as the oxidant. The removal efficiencies of the copper and zinc ions were 81.67% and 100%, respectively. The degradation of cyanide followed pseudo-first-order kinetics. Energy dispersive spectroscopy (EDS) results showed that the generally irregular surface of the catalyst with a high SiO2/Al2O3 ratio contains more nano-TiO2. The adsorption capacities of copper and zinc were relatively high. X-ray photoelectron spectroscopy (XPS) suggested that cyanide was eventually degraded to CO2 and NO3-. Copper and zinc were removed in the form of Cu(II) and Zn(II).

Synergetic Effect of Brønsted/Lewis Acid Sites and Water on the Catalytic Dehydration of Glucose to 5-Hydroxymethylfurfural by Heteropolyacid-Based Ionic Hybrids.

The effective dehydration of glucose to 5-hydroxymethylfurfural (HMF) has attracted increasing attention. Herein, a series of sulfonic-acid-functionalized ionic liquid (IL)-heteropolyacid (HPA) hybrid catalysts are proposed for the conversion of glucose to HMF. A maximum total yield of HMF and levoglucosan (LGA; ≈71 %) was achieved in the presence of pyrazine IL-HPA hybrid catalyst [PzS]H2PW in THF/H2O-NaCl (v/v 5:1). The mechanism of glucose dehydration was studied by tailoring the Brønsted/Lewis acid sites of the hybrid catalysts and altering the solvent composition. It was found that water and heteropolyanions have a significant effect on the reaction kinetics. Heteropolyanions are able to stabilize the intermediates and promote the direct dehydration of glucose and intermediate LGA to HMF. A small amount of water could facilitate the conversion of glucose to LGA and suppress the dehydration of LGA to levoglucosenone. In addition, the synergetic effect of Brønsted/Lewis acid sites and a little water was conducive to accelerated proton transfer, which improved the yield of HMF from glucose dehydration.

Three Dimensional Nitrogen-Doped and Nitrogen, Sulfur-Codoped Graphene Hydrogels for Electrode Materials in Supercapacitors.

In present work, reduced graphene oxide hydrogels (RGOHs) with three-dimensional (3D) porous structure are prepared through chemical reduction method by using aminourea (NRGOHs) and aminothiourea (NSRGOHs) as reductants. The as-prepared RGOHs are considered not only as promising electrode materials for supercapacitors, but also the doping of nitrogen (aminourea, NRGOHs) or nitrogen/sulfur (aminothiourea, NSRGOHs) can improve electrochemical performance through faradaic pseudocapacitance. The optimized samples have been prepared by controlling the mass ratios of graphene oxide (GO) to aminourea or aminothiourea to be 1:1, 1:2 and 1:5, respectively. With adding different amounts of aminourea or aminothiourea, the obtained RGOHs exhibited different electrochemical performance in supercapacitors. With increasing the dosage of the reductants, the RGOHs revealed better specific capacitances. Moreover, NSRGOHs with nitrogen, sulfur-codoping exhibited better capacitance performance than that of NRGOHs with only nitrogen-doping. NSRGOHs showed excellent capacitive performance with a very high specific capacitance up to 232.2, 323.3 and 345.6 F g-1 at 0.2 A g-1, while NRGOHs showed capacitive performance with specific capacitance up to 220.6, 306.5 and 332.7 F g-1 at 0.2 A g-1. This provides a strategy to improve the capacitive properties of RGOHs significantly by controlling different doping the materials.

Three-Dimensional Reduced Graphene Hydrogels Using Various Carbohydrates for High Performance Supercapacitors.

In present work, three-dimensional (3D) reduced graphene hydrogels (RGHs) are prepared through an efficient and facile strategy by employing three types of carbohydrates (glucose, fructose and sucrose) as reducing agents in aqueous solution of graphene oxide (GO) with ammonia. The formation of RGHs could be confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The structures and porosity were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and N2 sorption experiments. Benefiting from the abundant porous architectures as fast ionic channels for electrochemical energy storage, the prepared RGHs exhibited a high specific capacitance up to 153.5, 145.0 and 150.3 F g−1 at 0.3 A g−1 for FRGHs (fructose), GRGHs (glucose) and SRGHs (sucrose), which can be maintained for 61.4, 61.5 and 46.9% as the discharging current density was increased up to 20 A g−1. Moreover, it also showed that the electrode based on RGHs has good electrochemical stability and high degree of reversibility in the charge/discharge cycling test.

Reduced graphene oxide aerogel with high-rate supercapacitive performance in aqueous electrolytes.

Reduced graphene oxide aerogel (RGOA) is synthesized successfully through a simultaneous self-assembly and reduction process using hypophosphorous acid and I2 as reductant. Nitrogen sorption analysis shows that the Brunauer-Emmett-Teller surface area of RGOA could reach as high as 830 m2 g-1, which is the largest value ever reported for graphene-based aerogels obtained through the simultaneous self-assembly and reduction strategy. The as-prepared RGOA is characterized by a variety of means such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical tests show that RGOA exhibits a high-rate supercapacitive performance in aqueous electrolytes. The specific capacitance of RGOA is calculated to be 211.8 and 278.6 F g-1 in KOH and H2SO4 electrolytes, respectively. The perfect supercapacitive performance of RGOA is ascribed to its three-dimensional structure and the existence of oxygen-containing groups.

2-Amino-4-methyl-benzene-sulfonamide.

In the crystal of the title compound, C(7)H(10)N(2)O(2)S, the mol-ecules are linked by two strong N-H⋯O hydrogen bonds. The mol-ecular structure is stabilized by an intra-molecular N-H⋯O hydrogen bond. The C/S/N plane makes a dihedral angle of 69.7 (2)° with the aromatic ring plane.

4-(Methyl-sulfon-yl)benzaldehyde.

In the crystal of the title compound, C(8)H(8)O(3)S, the mol-ecules are linked into a three-dimensional array by inter-molecular C-H⋯O hydrogen bonds.

(E)-2-Methyl-N-[4-(methyl-sulfon-yl)benzyl-idene]aniline.

Mol-ecules of the title compound, C(15)H(15)NO(2)S, display an E configuration with respect to the C=N double bond. The crystal structure is stabilized by weak C-H⋯O hydrogen bonds. The dihedral angle between the two aromatic ring planes is 50.41 (12)°.

(E,E)-N,N'-Bis[4-(methyl-sulfon-yl)benzyl-idene]ethane-1,2-diamine.

In the crystal structure of the title Schiff base compound, C(18)H(20)N(2)O(4)S(2), the mol-ecule lies across a crystallographic inversion centre. The torsion angle of the N-C-C-N fragment is 180°, as the inversion centre bis-ects the central C-C bond. The crystal packing is stabilized by C-H⋯O hydrogen bonds and aromatic π-π stacking inter-actions with a centroid-centroid distance of 3.913 (2) Å.

Aqueous dye adsorption on ordered mesoporous carbons.

Ordered mesoporous carbons (OMCs) with varying pore size, and microporous carbon, CFY, were synthesized using ordered mesoporous silica SBA-15 and NaY zeolite as hard templates, respectively. N(2) adsorption tests show that the synthesized OMCs possess abundant mesopores and centralized mesopore distribution. Methylene blue (MB) and neutral red (NR) were used as probe molecules to investigate their adsorption behaviors on OMCs and CFY. As evidenced by adsorption tests, the volume of mesopores of which the pore size is larger than 3.5 nm is a crucial factor for the adsorption capacity and adsorption rate of MB on OMCs. However, the most probable pore diameter of OMCs was found to be vital to the adsorption capacity and adsorption rate of NR. Theoretical studies show that the adsorption kinetics of MB and NR on OMCs can be well depicted by using pseudo-second-order kinetic model.