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The development of environmentally friendly and safe chemical processes using renewable energy sources is important. In this study, a photoelectrochemical (PEC) cell was used for the tandem bromination of sp3carbon within a unique two-phase electrolyte system. By incorporation of a RuOxcocatalyst, the Ta3N5photoelectrode demonstrated a remarkable selectivity for Br2close to 100%. The kinetic study for charge carriers of photoelectrodes reveals that the improved charge transfer at Ta3N5/RuOxinterfaces contributed to excellent photoelectrochemical Br2evolution activity. The photoelectrochemically produced Br2was utilized for bromination of α-sp3carbon in toluene, 1-methylnaphthalene, ethylbenzene, or cyclohexane by the Ta3N5/RuOxphotoanode with 100% regioselectivity. The coupling of the Ta3N5photoanode and InP photocathode generated H2and Br2under light illumination without external bias. This study provides systematic insights into the design of photoelectrodes for solar-driven tandem bromination systems within the unique environment of a two-phase electrolyte system.

[Display omitted] • Pt/ZM catalysts were synthesized by the microwave-solvothermal method. • Effect of zeolite/MOF ratio and Pt content on the catalytic behavior was evaluated. • Hydrodeoxygenation of stearic acid with a conversion efficiency of 92% after 2 h. • Hydrocarbon selectivity is 10–11 times higher in the ZM-based catalyst case. • Good catalytic stability after 4 recycle runs during hydrodeoxygenation reaction. Herein, we report the synthesis of a series of zeolite-porous metal–organic framework (MOF) (ZM) composites with different Pt loadings via a two-step approach, in which –COOH functionalized ZSM-5 particles were added during the formation of MIL-100(Fe) (Materials Institute Lavoisier) by a microwave-assisted solvothermal method. The acidity of the ZM composites was significantly improved compared to that of the parent materials, and the highest acidity was observed for the ZM2-based catalyst. This ZM composite-supported Pt (Pt/ZM) catalyst was investigated as a promising candidate for the selective hydrodeoxygenation (HDO) of stearic acid as a fatty acid model compound. The effect of zeolite/MOF ratio and Pt content on the catalytic behavior was also evaluated. As a result, the 3% Pt/ZM2 catalyst showed a conversion efficiency of 92% for the stearic acid HDO with a hydrocarbon selectivity of 10–11 times higher than that of the original Pt/MIL-100 (Fe). In addition, 3% Pt/ZM2 catalyst exhibited stable catalytic performance for stearic acid HDO during the recycle runs. The optimized Pt/ZM catalyst showed high thermal and catalytic stability, as well as high product yield. [ABSTRACT FROM AUTHOR]

Nickel is considered an economically feasible catalyst for the dry reforming of methane (DRM) owing to its high activity. Because the highly endothermic DRM requires a high reaction temperature to activate both CH4and CO2, deactivation of the Ni catalyst may be induced by sintering and carbon coking. To mitigate catalyst deactivation, Ni/CeO2catalysts composed of monodisperse Ni nanoparticles supported on CeO2nanorods are designed and coated with Al2O3layers by atomic layer deposition (ALD). The performance of the catalyst in DRM and amount of carbon deposited are correlated with the thickness of the Al2O3layer in the Ni/CeO2/Al2O3catalysts. As the number of ALD cycles increases from 1 to 10, the conversion of CO2and CH4at 700 and 800 °C decreases, but the Ni/CeO2/Al2O3catalysts remain coke-free as thermogravimetric analysis shows no weight loss up to 800 °C. The Al2O3layer generated by ALD curtails the coking substantially, but the weakly metallic character of Ni and blocking of Ni sites by the Al2O3layer are the major factors contributing to decreasing the catalytic conversion. The ALD technique provides an efficient way to fabricate atomically controlled oxide layers for improving the stability of catalysts against coke deposition and sintering.

Since adsorption performances are dominantly determined by adsorbate–adsorbent interactions, accurate theoretical prediction of the thermodynamic characteristics of gas adsorption is critical for designing new sorbent materials as well as understanding the adsorption mechanisms. Here, through our molecular modeling approach using a newly developed quantum-mechanics-based force field, it is demonstrated that the CO2adsorption selectivity of SBA-15 can be enhanced by incorporating crystalline potassium chloride particles. It is noted that the induced intensive electrostatic fields around potassium chloride clusters create gas-trapping sites with high selectivity for CO2adsorption. The newly developed force field can provide a reliable theoretical tool for accurately evaluating the gas adsorption on given adsorbents, which can be utilized to identify good gas adsorbents.

Solid acid catalysts based on silica–alumina (SiO 2 -Al 2 O 3 ) were used for promoting furfural production from D-xylose, and the partial least squares model was applied to develop an empirical kinetic model. Considering the experimental error and measurement noise, ∼85% of variances for the output block comprising the D-xylose conversion and selectivities were used by employing three latent variables, and the comparison between experimental and simulation results demonstrated the effectiveness of the model. The effects of the operating conditions, including xylose concentration, temperature, and space velocity were evaluated using the developed model, and optimal conditions for the maximum furfural productivity were determined. [ABSTRACT FROM AUTHOR]

The effects of cations of zeolite for the adsorption of organosulfur compounds were investigated by using density functional theory calculations. The binding energies of tetrahydrothiophene (C4H8S, THT), dimethyl sulfide (C2H6S, DMS), tert-butylmercaptan (C4H10S, TBM), hydrogen sulfide (H2S), and carbonyl sulfide (COS) on the zeolite model clusters [X(HO)3SiOAl(OH)3, X = H+, Na+and Ag+] were obtained and compared with those of H2O, CO2, and C1−C3light hydrocarbons. Compared to the H+and Na+cations, the Ag+cation induces much stronger binding of THT, DMS, TBM, and H2S over H2O suggesting great enhancements in the adsorption selectivity. The order of binding energies of these sulfur compounds is THT > DMS > TBM > H2S > COS, and it does not depend on the cation types. These results agree well with the experimental adsorption uptake and selectivity properties of AgNaY zeolites for organosulfur compounds.

The selective catalytic reduction of NOx with NH3 (NH3-SCR) was investigated over Pt catalysts supported on various supports such as alumina, ZSM-5, SBA-15, and Al-SBA-15 with different amounts of alumina. Among them, Pt catalysts supported on Al-SBA-15 showed the higher NOx conversion at low temperatures than those of others. These also showed high NOx conversions over a wide reaction temperature. As the Si/Al ratio in Al-SBA-15 decreased, the NH3-SCR activity increased. This was closely related to the amount of strongly-adsorbed NH3.

Carbon-supported palladium catalysts were prepared by an impregnation method using palladium chloride and different carbon supports such as activated carbons with different surface oxygen concentrations and a mesoporous carbon, CMK-5.. The different degree of surface oxidation was achieved by the nitric acid and high-temperature heat treatment. The molecular PdCl2 species was stabilized by adding an HCl in an impregnation step.. As the reduction temperature increased, the Pd dispersion decreased for all Pd catalysts. There was no noticeable difference in Pd dispersion among Pd catalysts supported on carbon supports with different physicochemical properties when the reduction temperature was 423 K. Pd catalysts supported on the carbon support with a high concentration of surface oxygen groups showed a better dispersion than did other Pd catalysts when they were reduced at 573 K. The maximum Pd dispersion was observed over Pd catalyst supported on carbon supports with the highest surface area when the reduction temperature was higher than 573 K.

Au/CeO2 catalysts prepared by a deposition-precipitation and a co-precipitation method were applied to CO oxidation in the absence and presence of hydrogen. The transmission electron microscope (TEM), the temperature programmed reduction (TPR), and the X-ray absorption near edge structure (XANES) were conducted to probe structural and electronic properties of gold. Au2O3 was determined to be mainly present when Au/CeO2 was prepared by a deposition-precipitation method. However, the metallic gold was observed in a co-precipitated Au/CeO2 catalyst. Au/CeO2 containing oxidized gold species, prepared by a deposition-precipitation method, showed the decreasing CO conversion with a reaction time, which accompanied the reduction of gold from Au(+3) to Au(0). However, co-precipitated Au/CeO2 showed the stable CO conversion. The effect of pretreatment condition on CO oxidation was also examined. These results support that Au/CeO2 catalyst containing oxidized gold species was superior to Au/CeO2 catalyst containing the metallic gold for CO oxidation. This Au/CeO2 catalyst was also active for the selective CO oxidation in the presence of hydrogen.

The effect of a microwave-enhanced wet chemical etching process of SiC particles on the electroless copper plating and on the Al/Cu-coated SiC composites was investigated. The microwave-enhanced wet etching process increased the concentration of surface oxides on SiC. The BET surface area of SiC increased, reached its maximum value at 30 s, and then decreased during an etching process. The enhanced chemical adhesion strength between the coated copper and SiC was observed after an etching process. Furthermore, the sintering density and transverse rupture strength (TRS) of Al/Cu-coated SiC composites were improved when SiC particles were etched. This result indicated that the microwave-enhanced etching of SiC particles also improved chemical and mechanical adhesion of Al/Cu-coated SiC composites.

Carbon-supported Pd catalysts with a copper compound for the oxidation of methane to a methanol derivative, CF3COOCH3, in the presence of CO and O2were characterized. The bulk structure and chemical environment of palladium and copper were determined by XRD and XAFS, respectively. In this reaction system, the nature of cocatalyst, the presence of Cl−, and the solvent composition changed the structure of the palladium species and affected the yield of CF3COOCH3. In the presence of a copper compound and Cl−, the metallic palladium can be partly oxidized into Pd(II) species, which resulted in higher yields of CF3COOCH3. For the active catalyst system, the copper compound was present as CuCl. Pd(II) species coordinated with Cl−appeared to be essential for the selective activation of methane and the metallic palladium for the in situgeneration of H2O2from CO, H2O, and O2.

The effect of surface treatment of the support on the oxidation of carbon monoxide over carbon-supported Wacker-type catalysts was examined. Temperature-programmed desorption (TPD) and FT-IR were used to characterize the surface functional groups of carbon. XRD patterns and XAFS spectra of the catalysts were measured to determine the structure and the chemical environment of palladium and copper. Carboxylic and carbonyl groups were enriched on the carbon support by the pretreatment of the support with HNO3or the addition of Cu(NO3)2as a copper precursor. These surface groups increased the hydrophilicity determined by H2O-TPD, and promoted the formation of active copper phase, Cu2Cl(OH)3. This appears to be responsible for the observed promotional effect on CO oxidation when Cu(NO3)2was added as an additional copper precursor.

Effects of copper phase on oxidation of carbon monoxide over supported Wacker-type catalysts were examined. XRD patterns and XANES spectra of the catalysts were measured to determine the bulk phase and the chemical environment of copper. The catalytic activity was affected by the composition of copper precursors, the nature of supports, the presence of HCl and SO2in the feed, and the reaction temperature. All these variables affecting the catalytic activity influenced the XRD intensity of Cu2Cl(OH)3phase in the same manner, which was believed to be the active copper phase of the catalyst. Thus the XRD intensity of Cu2Cl(OH)3of a catalyst was closely correlated with its catalytic activity and the change in the catalytic activity of CO oxidation with respect to different reaction and preparation conditions was directly related to the behavior of the active copper phase with respect to those variables.

Supported gold catalysts were prepared by a deposition–precipitation method and characterized to understand the different activities for CO oxidation with different pretreatment conditions. Gold catalysts supported on Fe2O3, TiO2, and Al2O3showed decreasing activity with increasing calcination temperatures, with the Al2O3-supported catalyst showing activity substantially lower than that of the other two catalysts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) studies showed the phase transition of gold from Au(OH)3through Au2O3to metallic gold with increasing calcination temperatures for all catalysts. In addition to the particle size of metallic gold, the oxidation states of gold were proven to be important for CO oxidation. The oxidized gold species were more active than metallic gold. Furthermore, facile formation of the interface between gold and support appears to be critical for high CO oxidation activity of supported gold catalysts.

A population of procollagen molecules has been isolated from the culture medium of a clonal line of calf dermatosparactic cells and shown to have the amino-acid composition, physical properties, and molecular structure consistent with collagen precursors. Although this procollagen population shares immunologic determinants with the procollagen obtained from dermatosparactic skin, it differs from the latter in aminoacid composition, in subunit properties, and by its content of bothamino and carboxyl terminal non-collagen peptide appendages. We propose that the cell culture procollagen contains earlier biosynthetic forms of dermatosparactic procollagen.

An atomic gradient passivation layer, (Ta,Mo)x(O,S)y, is designed to improve the charge transportation and photoelectrochemical activity of CuInS2-based photoelectrodes. We found that Mo spontaneously diffused to the a-TaOxlayer during e-beam evaporation. This result indicates that the gradient profile of MoOx/TaOxis formed in the sublayer of (Ta,Mo)x(O,S)y. To understand the atomic-gradation effects of the (Ta,Mo)x(O,S)ypassive layer, the composition and (photo)electrochemical properties have been characterized in detail. When this atomic gradient-passive layer is applied to CuInS2-based photocathodes, promising photocurrent and onset potential are seen without using Pt cocatalysts. This is one of the highest activities among reported CuInS2photocathodes, which are not combined with noble metal cocatalysts. Excellent photoelectrochemical activity of the photoelectrode can be mainly achieved by (1) the electron transient time improved due to the conductive Mo-incorporated TaOxlayer and (2) the boosted electrocatalytic activity by Mox(O,S)yformation.

In the presence of an optimized chiral organocatalyst and TiO2, aldehydes with TEMPO to give the corresponding α‐piperidinyloxy‐substituted aldehydes in a highly chemo‐ and stereoselective manner.

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