Conversion of succinic acid to 1,4-butanediol via dimethyl succinate over rhenium nano-catalyst supported on copper-containing mesoporous carbon.

Copper-containing mesoporous carbons (XCu-MC) with different copper content (X = 8.0, 12.7, 15.9, 23.3, and 26.8 wt%) were prepared by a single-step surfactant-templating method. Rhenium nano-catalysts supported on copper-containing mesoporous carbons (Re/XCu-MC) were then prepared by an incipient wetness method. Re/XCu-MC (X = 8.0, 12.7, 15.9, 23.3, and 26.8 wt%) catalysts were characterized by nitrogen adsorption-desorption isotherm, HR-TEM, FT-IR, and H2- TPR analyses. Liquid-phase hydrogenation of succinic acid to 1,4-butanediol (BDO) via dimethyl succinate (DMS) was carried out over Re/XCu-MC catalysts in a batch reactor. The effect of copper content on the physicochemical properties and catalytic activities of Re/XCu-MC catalysts in the hydrogenation of succinic acid to BDO was investigated. Re/XCu-MC catalysts retained different physicochemical properties depending on copper content. In the hydrogenation of succinic acid to BDO, yield for BDO showed a volcano-shaped trend with respect to copper content. Thus, an optimal copper content was required to achieve maximum catalytic performance of Re/XCu-MC. It was also observed that yield for BDO increased with increasing the amount of hydrogen consumption by copper in the Re/XCu-MC catalysts.

Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) heteropolyacid nano-catalysts for catalytic decomposition of 2,3-dihydrobenzofuran to aromatics.

Cesium-exchanged Cs(x)H(3.0-x)PW12O40 (X = 2.0, 2.3, 2.5, 2.8, and 3.0) heteropolyacid nanocatalysts were prepared, and they were applied to the catalytic decomposition of lignin model compound to aromatics. Successful formation of cesium-exchanged Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts was confirmed by FT-IR, ICP-AES, and XRD measurements. 2,3-Dihydrobenzofuran was employed as a lignin model compound for representing ß-5 bond in lignin. Phenol, ethylbenzene, and 2-ethylphenol were mainly produced by the catalytic decomposition of 2,3-dihydrobenzofuran. Conversion of 2,3-dihydrobenzofuran and total yield for main products (phenol, ethylbenzene, and 2-ethylphenol) were closely related to the surface acidity of Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts. Conversion of 2,3-dihydrobenzofuran and total yield for main products increased with increasing surface acidity of the catalysts. Among the catalysts tested, Cs2.5H0.5PW12O40 with the largest surface acidity showed the highest conversion of 2,3-dihydrobenzofuran and the highest total yield for main products. These results indicate that surface acidity of Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts served as an important factor determining the catalytic performance in the decomposition of 2,3-dihydrobenzofuran to aromatics.

Characterization and electrochemical performance of graphene-containing carbon aerogel for supercapacitor.

Graphene-containing carbon aerogel was prepared by a polycondensation of resorcinol with formaldehyde using chemically exfoliated graphene oxide in ambient conditions, and its electrochemical performance as an electrode for supercapacitor was examined. The effect of pH in the preparation of RFGO (resorcinol-formaldehyde and graphene oxide) solution on the physical and electrochemical properties of graphene-containing carbon aerogel was investigated. For comparison, graphene-free carbon aerogel was also prepared. Among the samples, graphene-containing carbon aerogel prepared at pH 6.5 showed the highest BET surface area (733 m2/g) and the largest pore volume (1.39 cm3/g) with well-developed porous structure. Electrochemical properties of graphene-containing carbon aerogel and graphene-free carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and by charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. From cyclic voltammetry measurements, it was found that graphene-containing carbon aerogel prepared at pH 6.5 showed higher specific capacitance than graphene-free carbon aerogel (63 F/g vs. 54 F/g). Specific capacitance calculated by charge/discharge test also revealed that graphene-containing carbon aerogel prepared at pH 6.5 showed higher specific capacitance than graphene-free carbon aerogel (85 F/g vs. 79 F/g). Thus, electrochemical performance of graphene-containing carbon aerogel prepared at pH 6.5 could be enhanced by adding graphene into carbon aerogel.

Catalytic cracking of C5 raffinate to light olefins over phosphorous-modified microporous and mesoporous ZSM-5.

Phosphorous-modified microporous and mesoporous ZSM-5 catalysts (XP/C-ZSM5) were prepared with a variation of phosphorous content (X = 0.17, 0.3, 0.7, 1.4, and 2.7 wt%), and they were applied to the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. The effect of phosphorous content on the physicochemical properties and catalytic activities of XP/C-ZSM5 catalysts was investigated. It was revealed that physicochemical properties of XP/C-ZSM5 catalysts were strongly influenced by phosphorous content. Strong acidity of XP/C-ZSM5 catalysts decreased with increasing phosphorous content. In the catalytic cracking of C5 raffinate, both conversion of C5 raffinate and yield for light olefins (ethylene and propylene) showed volcano-shaped curves with respect to strong acidity. This result indicates that strong acidity of XP/C-ZSM5 catalysts played an important role in determining the catalytic performance in the catalytic cracking of C5 raffinate. Among the catalysts tested, 0.3P/C-ZSM5 catalyst with moderate strong acidity showed the best catalytic performance.

Catalytic decomposition of 4-phenoxyphenol to aromatics over Pd/Cs(x)H3.0-x PW12O40/activated carbon aerogel (X = 2.0-3.0).

Cesium-exchanged heteropolyacid (Cs(x)H3.0-xPW12O40) was impregnated onto activated carbon aerogel (ACA) with a variation of cesium content (X = 2.0, 2.3, 2.5, 2.7, and 3.0) in order to provide acid sites to ACA. Palladium catalysts were then supported on Cs(x)H3.0-xPW12O40-impregnated activated carbon aerogel (Pd/Cs(x)H3.0-xPW12O40/ACA, X = 2.0-3.0) by an incipient wetness impregnation method for use in the decomposition of lignin model compound to aromatics. 4-Phenoxyphenol was used as a lignin model compound for representing 4-O-5 linkage of lignin. In the catalytic decomposition of 4-phenoxyphenol over Pd/Cs(X)H3.0-xPW12O40/ACA, cyclohexanol, benzene, and phenol were mainly produced. Conversion of 4-phenoxyphenol and total yield for main products (cyclohexanol, benzene, and phenol) were closely related to the acidity of Pd/Cs(x)H3.0-xPW12O40/ACA. Conversion of 4-phenoxyphenol and total yield for main products increased with increasing acidity of Pd/Cs(x)H3.0-xPW12O40/ACA. Among the catalysts tested, Pd/Cs2.5H0.5PW12O40/ACA catalyst with the largest acidity showed the highest conversion of 4-phenoxyphenol and total yield for main products. Therefore, it is concluded that acidity of catalysts would be an important factor determining the catalytic performance in the decomposition of 4-phenoxyphenol.

Hydrogenation of succinic acid to 1,4-butanediol over rhenium catalyst supported on copper-containing mesoporous carbon.

Copper-containing mesoporous carbon (Cu-MC) was prepared by a single-step surfactant-templating method. For comparison, copper-impregnated mesoporous carbon (Cu/MC) was also prepared by a surfactant-templating method and a subsequent impregnation method. Rhenium catalysts supported on copper-containing mesoporous carbon and copper-impregnated mesoporous carbon (Re/Cu-MC and Re/Cu/MC, respectively) were then prepared by an incipient wetness method, and they were applied to the liquid-phase hydrogenation of succinic acid to 1,4-butanediol (BDO). It was observed that copper in the Re/Cu-MC catalyst was well incorporated into carbon framework, resulting in higher surface area and larger pore volume than those of Re/Cu/MC catalyst. Therefore, Re/Cu-MC catalyst showed higher copper dispersion than Re/Cu/MC catalyst, although both catalysts retained the same amounts of copper and rhenium. In the liquid-phase hydrogenation of succinic acid to BDO, Re/Cu-MC catalyst showed a better catalytic activity than Re/Cu/MC catalyst. Fine dispersion of copper in the Re/Cu-MC catalyst was responsible for its enhanced catalytic activity.

Oxidative dehydrogenation of n-butane over magnesium vanadate nano-catalysts supported on magnesia-zirconia: effect of vanadium content.

Magnesia-zirconia (MgO-ZrO2) support was prepared by a sol-gel method, and magnesium vanadate nano-catalysts supported on magnesia-zirconia (X-Mg3(VO4)2/MgO-ZrO2) were then prepared by a wet impregnation method with a variation of vanadium content (X = 6.6, 9.9, 12.8, 15.2, and 19.1 wt%). X-Mg3(VO4)2/MgO-ZrO2 nano-catalysts were applied to the oxidative dehydrogenation of n-butane to n-butene and 1,3-butadiene. The formation of X-Mg3(VO4)2/MgO-ZrO2 nano-catalysts was well confirmed by XRD, XPS, and ICP-AES analyses. 15.2-Mg3(VO4)2/MgO-ZrO2 and 19.1-Mg3(VO4)2/MgO-ZrO2 catalysts experienced a catalyst deactivation, while the other Mg3(VO4)2/MgO-ZrO2 catalysts showed a stable catalytic performance during the whole reaction time. The effect of oxygen property of X-Mg3(VO4)2/MgO-ZrO2 nano-catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic performance, while oxygen mobility of the catalyst played an important role in the catalyst stability. Among the catalysts tested, 12.8-Mg3(VO4)2/MgO-ZrO2 catalyst showed the best catalytic performance in terms of yield for TDP (total dehydrogenation products).

Oxidative dehydrogenation of n-butane over vanadium magnesium oxide catalysts supported on nano-structured MgO and ZrO2: effect of oxygen capacity of the catalyst.

Vanadium-magnesium oxide catalysts supported on nano-structured MgO and ZrO2 (Mg3(VO4)2/MgO/ZrO2) were prepared by a wet impregnation method with a variation of Mg:Zr ratio (8:1, 4:1, 2:1, and 1:1). For comparison, Mg3(VO4)2/MgO and Mg3(VO4)2/ZrO2 catalysts were also prepared by a wet impregnation method. The prepared catalysts were applied to the oxidative dehydrogenation of n-butane in a continuous flow fixed-bed reactor. Mg3(VO4)2/MgO/ZrO2 (Mg:Zr = 4:1, 2:1, and 1:1) and Mg3(VO4)2/ZrO2 catalysts showed a stable catalytic activity during the whole reaction time, while Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts experienced a severe catalyst deactivation. Deactivation of Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts was due to their low oxygen mobility. Effect of oxygen capacity (the amount of oxygen in the catalyst involved in the reaction) of the supported Mg3(V04)2 catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic activity in the oxidative dehydrogenation of n-butane. A large oxygen capacity of the catalyst was favorable for obtaining a high catalytic activity in this reaction. Among the catalysts tested, Mg3(VO4)2/MgO/ZrO2 (4:1) catalyst with the largest oxygen capacity showed the best catalytic performance.

Hydrogenation of CO to methane over mesoporous nickel-iron-alumina xerogel nano-catalysts.

Mesoporous nickel-iron-alumina xerogel ((40-x)Ni(x)FeAX) nano-catalysts with different iron content (x = 0, 2.5, 5, 7.5, and 10) were prepared by a single-step sol-gel method for use in the methane production from carbon monoxide and hydrogen. The effect of iron content on the catalytic performance of (40-x)Ni(x)FeAX catalysts was investigated. In the methanation reaction, yield for CH4 decreased in the order of 35Ni5FeAX > 32.5Ni7.5FeAX > 30Ni10FeAX > 37.5Ni2.5FeAX > 40Ni0FeAX. This indicated that optimal iron content of mesoporous nickel-iron-alumina xerogel nano-catalyst was required for maximum production of CH4 in the methanation reaction. Experimental results revealed that optimal CO dissociation energy and large H2 adsorption ability of the catalyst were favorable for methane production. Among the catalysts tested, 35Ni5FeAX catalyst, which retained the most optimal CO dissociation energy and the largest H2 adsorption ability, exhibited the best catalytic performance in terms of conversion of CO and yield for CH4 in the methanation reaction. CO dissociation energy and H2 adsorption ability of the catalyst played a key role in determining the catalytic performance of (40-x)Ni(x)FeAX in the methanation reaction.

Enhancing the evanescent field in TiO2/Au hybrid thin films creates a highly sensitive room-temperature formaldehyde gas biosensor.

Discovery of the relationship between disease and the volatile organic compounds (VOCs) contained in respiratory gas in human bodies has led to the development of analytical methods and detection systems that can be used for diagnosis. Recent studies, however, have encountered problems using these diagnostic tools when operation temperatures are too high and the detection range of the gas concentration falls beyond the limits of diagnosis criteria. In this study, we propose a highly sensitive surface plasmon resonance (SPR) biosensor that is based on an enhanced evanescent wave technique and can be operated at room temperature (RT) for the detection of formaldehyde. The detection system relies on an improved Kretschmann configuration with an enhanced signal transducer algorithm and a novel microfluidic gas channel that can accomplish highly sensitive quantification using ligand-modified TiO2/Au hybrid thin film as a RT-operated sensing interface. The detection of formaldehyde was chosen to test this concept, because formaldehyde is a known breast cancer biomarker that exists in human exhalation. When the interface of our sensing system was exposed to formaldehyde, the interaction between the ligand and the analyte produced changes in the SPR profiles of the gold thin film. The linear range of the detection system was 0.2-1.8 ppm with limit of detection at 0.2 ppm. The diagnostic criteria suggest this method could be applied to biological monitoring and diagnostics.

Production of Light Olefins Through Catalytic Cracking of C5 Raffinate Over Surface-Modified ZSM-5 Catalyst.

Surface modification of phosphorous-containing porous ZSM-5 catalyst (P/C-ZSM5-Sil.(X)) was carried out by a chemical liquid deposition (CLD) method using tetraethyl orthosilicate (TEOS) as a silylation agent. Different amount of TEOS (X = 5, 10, 20, and 30 wt%) was introduced into P/C-ZSM5il.(X) catalysts for surface modification. The catalysts were used for the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. It was found that external surface acidity of P/C-ZSM5-Sil.(X) catalysts significantly decreased with increasing TEOS content. In the catalytic reaction, both conversion of C5 raffinate and yield for light olefins showed volcano-shaped curves with respect to TEOS content. Among the catalysts tested, P/C-ZSM5-Sil.(20) catalyst exhibited the best catalytic performance in terms of conversion of C5 raffinate and yield for light olefins. Thus, an optimal TEOS content was required for CLD treatment to maximize light olefin production in the catalytic cracking of C5 raffinate over P/C-ZSM5-Sil.(X) catalysts.

Catalytic Decomposition of 2,3-Dihydrobenzofuran to Monocyclic Compounds Over Palladium Catalysts Supported on Sulfonated Ordered Mesoporous Carbon.

Ordered mesoporous carbon (OMC) was sulfonated at different temperature (OMC-SO3H-X, X = 125, 150, 175, 200, and 225 degrees C) in order to provide acid sites to OMC. Palladium catalysts were then supported on OMC-SO3H-X by an incipient wetness impregnation method for use in the catalytic decomposition of 2,3-dihydrobenzofuran to monocyclic compounds. 2,3-Dihydrobenzofuran was used as a lignin model compound for representing ß-5 linkage of lignin. In the catalytic decomposition of 2,3-dihydrobenzofuran over Pd/OMC-SO3H-X, ethylcyclohexane and 2-ethlyphenol were mainly produced. Conversion of 2,3-dihydrobenzofuran and total yield for main products (ethylcyclohexane and 2-ethylphenol) were closely related to the acidity of the catalysts. Conversion of 2,3-dihydrobenzofuran and total. yield for main products increased with increasing acidity of Pd/OMC-SO3H-X catalysts. Among the catalysts tested, Pd/OMC-SO3H-150 with the largest acidity showed the highest conversion of 2,3-dihydrobenzofuran and the highest total yield for main products.

Platinum-Tin Nano-Catalysts Supported on Alumina for Direct Dehydrogenation of n-Butane.

Al2O3 supports were prepared by a precipitation method using various basic solutions (NaOH, KOH, NH4OH, and Na2CO3) as precipitation agents, and Pt/Sn/Al2O3 nano-catalysts were then prepared by a sequential impregnation method. The prepared catalysts were applied to the direct dehydrogenation of n-butane to n-butenes and 1,3-butadiene. The effect of precipitation agents on the physicochemical properties and catalytic activities of Pt/Sn/Al2O3 nano-catalysts in the direct dehydrogenation of n-butane was investigated. Catalytic performance of Pt/Sn/Al2O3 nano-catalysts decreased in order of Pt/Sn/Al2O3 (NaOH) > Pt/Sn/Al2O3 (KOH) > Pt/Sn/Al2O3 (NH4OH) > Pt/Sn/Al2O3 (Na2CO3). Among the catalysts tested, Pt/Sn/Al2O3 (NaOH) nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butenes and 1,3-butadiene). Hydrogen chemisorption experiments revealed that platinum surface area of the catalyst was closely related to the catalytic performance. Yield for TDP increased with increasing platinum surface area of the catalyst.

Direct Dehydrogenation of n-Butane Over Pt/Sn/Zn/γ-Al2O3 Nano-Catalyst: Effect of Zn Content.

A series of Pt/Sn/XZn/γ-Al2O3 nano-catalysts with different Zn content (X = 0, 0.25, 0.5, 0.75, and 1.0 wt%) were prepared by a sequential impregnation method. They were applied to the direct dehydrogenation of n-butane to n-butene and 1,3-butadiene. The effect of zinc content of Pt/Sn/XZn/γ-Al2O3 nano-catalysts on their physicochemical properties and catalytic activities in the direct dehydrogenation of n-butane was investigated. The catalytic performance of Pt/Sn/XZn/γ-Al2O3 nano-catalysts strongly depended on zinc content. Among the catalysts tested, Pt/Sn/0.5Zn/γ-Al2O3 nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butene and 1,3-butadiene). TPR (temperature-programmed reduction) and H2-chemisorption experiments were carried out to measure metal-support interaction and Pt surface area of the catalysts. Experimental results revealed that metal-support interaction and Pt surface area of the catalysts were closely related to the catalytic performance. Yield for TDP increased with increasing metal-support interaction and Pt surface area of the catalysts.

CO2 Activated Carbon Aerogel with Enhanced Electrochemical Performance as a Supercapacitor Electrode Material.

Carbon aerogel (CA) was prepared by a sol-gel polymerization of resorcinol and formaldehyde in ambient conditions. A series of activated carbon aerogels (ACA-X, X = 1, 2, 3, 4, 5, and 6 h) were then prepared by CO2 activation of CA with a variation of activation time (X) for use as an electrode material for supercapacitor. Specific capacitances of CA and ACA-X electrodes were measured by cyclic voltammetry and galvanostatic charge/discharge methods in 6 M KOH electrolyte. Among the samples, ACA-5 h showed the highest BET surface area (2574 m2/g) and the highest specific capacitance (100 F/g). It was found that CO2 activation was a very efficient method for enhancing physicochemical property and supercapacitive electrochemical performance of activated carbon aerogel.

Microporous and mesoporous ZSM-5 catalyst for catalytic cracking of C5 raffinate to light olefins.

ZSM5 catalysts (PAM(X)-ZSM5) with micropores and mesopores were prepared using polyacrylamide (PAM) as a soft template at different PAM content (X = 0, 0.12, 0.25, 0.53, 0.64, and 0.78 wt%), and they were applied to the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. The effect of PAM content of PAM(X)-ZSM5 catalysts on the physicochemical properties and catalytic activities was investigated. N2 adsorption-desorption isotherms of PAM(X)-ZSM5 catalysts exhibited a broad hysteresis loop at high relative pressure, indicating the existence of mesopores in the catalysts. It was found that the catalytic performance of PAM(X)-ZSM5 catalysts was closely related to the mesoporosity of the catalysts. Conversion of C5 raffinate and yield for light olefins showed volcano-shaped trends with respect to mesopore/micropore volume ratio of the catalysts. Thus, an optimal PAM content was required to achieve maximum production of light olefins through catalytic cracking of C5 raffinate over microporous and mesoporous PAM(X)-ZSM5 catalysts.

Mg3(VO4)2-MgO-ZrO2 nano-catalysts for oxidative dehydrogenation of n-butane.

A series of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts with different vanadium content (X = 3.3, 5.3, 7.0, 10.2, and 13.4) were prepared by a single-step citric acid-derived sol-gel method for use in the oxidative dehydrogenation of n-butane to n-butene and 1,3-butadiene. The effect of vanadium content of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts on their physicochemical properties and catalytic activities in the oxidative dehydrogenation of n-butane was investigated. Successful formation of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts was confirmed by XRD, Raman spectroscopy, and ICP-AES analyses. The catalytic performance of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts strongly depended on vanadium content. All the X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts showed a stable catalytic performance without catalyst deactivation during the reaction. Among the catalysts tested, 7.0-Mg3(VO4)2-MgO-ZrO2 nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butene and 1,3-butadiene). TPRO (temperature-programmed reoxidation) experiments were carried out to measure the oxygen capacity of the catalyst. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic performance. Yield for TDP increased with increasing oxygen capacity of the catalyst.