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1.
This research is aimed to improve the activity and stability of ternary alloy Pt–Ru–Ni/C catalyst. A novel anodic catalyst for direct methanol fuel cell (DMFC), carbon supported Pt–Ru–Ni–P nanoparticles, has been prepared by chemical reduction method by using NaH2PO2 as a reducing agent. One glassy carbon disc working electrode is used to test the catalytic performances of the homemade catalysts by cyclic voltammetric (CV), chronoamperometric (CA) and amperometric i–t measurements in a solution of 0.5 mol L–1 H2SO4 and 0.5 mol L–1 CH3OH. The compositions, particle sizes and morphology of home‐made catalysts are evaluated by means of energy dispersive analysis of X‐ray (EDAX), X‐ray diffraction (XRD) and transmission electron micrographs (TEM), respectively. TEM images show that Pt–Ru–Ni–P nanoparticles have an even size distribution with an average diameter of less than 2 nm. The results of CV, CA and i–t curves indicate that the Pt–Ru–Ni–P/C catalyst shows significantly higher activity and stability for methanol electrooxidation due to the presence of non‐metal phosphorus in comparison to Pt–Ru–Ni/C one. All experimental results indicate that the addition of non‐metallic phosphorus into the Pt–Ru–Ni/C catalyst has definite value of research and practical application for enhancing the performance of DMFC. 相似文献
2.
Hydrogen production by partial oxidation of methanol (POM) was investigated over Au–Ru/Fe2O3 catalyst, prepared by deposition–precipitation. The activity of Au–Ru/Fe2O3 catalyst was compared with bulk Fe2O3, Au/Fe2O3 and Ru/Fe2O3 catalysts. The reaction parameters, such as O2/CH3OH molar ratio, calcination temperature and reaction temperature were optimized. The catalysts were characterized by ICP, XRD, TEM and TPR analyses. The catalytic activity towards hydrogen formation is found to be higher over the bimetallic Au–Ru/Fe2O3 catalyst compared to the monometallic Au/Fe2O3 and Ru/Fe2O3 catalysts. Bulk Fe2O3 showed negligible activity towards hydrogen formation. The enhanced activity and stability of the bimetallic Au–Ru/Fe2O3 catalyst has been explained in terms of strong metal–metal and metal–support interactions. The catalytic activity was found to depend on the partial pressure of oxygen, which also plays an important role in determining the product distribution. The catalytic behavior at various calcination temperatures suggests that chemical state of the support and particle size of Au and Ru plays an important role. The optimum calcination temperature for hydrogen selectivity is 673 K. The catalytic performance at various reaction temperatures, between 433 and 553 K shows that complete consumption of oxygen is observed at 493 K. Methanol conversion increases with rise in temperature and attains 100% at 523 K; hydrogen selectivity also increases with rise in temperature and reaches 92% at 553 K. The overall reactions involved are suggested as consecutive methanol combustion, partial oxidation, steam reforming and decomposition. CO produced by methanol decomposition is subsequently transformed into CO2 by the water gas shift and CO oxidation reactions. 相似文献
3.
The electronegativity of Li is much higher than that of Na or K, but the ammonia synthesis activities of Li-promoted Ru/AC catalysts were comparable to the values of Ru catalyst promoted with K, which were much higher than those over Ru catalyst with Na promoter. The presence of Li increased the catalytic activity by changing the chemisorption properties such as hydrogen adsorption and nitrogen adsorption for carbon-supported Ru catalysts, rather than affecting the sizes of Ru particles or the electron density of Ru metal. 相似文献
4.
The effects of promoters K, Ba, Sm on the resistance to carbon-methanation and catalytic activity of ruthenium supported on active carbon (Ru/AC) for ammonia synthesis have been studied by means of TG-DTG (thermalgravity-differential thermalgravity), temperature-programmed desorption, and activity test. Promoters Ba,K, and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly. Much higher activity can be reached for Ru/AC catalyst with bi- or tri-promoters. Indeed, the triply promoted catalyst showed the highest activity, coupled to a surprisingly high resistance to methanation. The ability of resistance of promoter to methanation of Ru/AC catalyst is dependent on the adsorption intensity of hydrogen. The strong adsorption of hydrogen would enhance methanation and impact the adsorption of nitrogen, which results in the decrease of catalytic activity. 相似文献
5.
Bimetallic Ru–Re/SiO2 and monometallic Ru/SiO2 catalysts were prepared by impregnation method and their catalytic performances were evaluated in the hydrogenolysis of glycerol to propanediols (1,2-propanediol and 1,3-propanediol) with a batch type reactor (autoclave) under the reaction conditions of 160 °C, 8.0 MPa and 8 h. Ru–Re/SiO2 showed much higher activity in the hydrogenolysis of glycerol than Ru/SiO2, and the pretreatment conditions of the catalyst precursors had great influence on the catalytic performance of both Ru–Re/SiO2 and Ru/SiO2 catalysts. The physicochemical properties of Ru–Re/SiO2 and Ru/SiO2, such as specific surface areas, crystal phases, morphologies/microstructures, surface element states, reduction behaviors and dispersion of Ru metal, were characterized by N2 adsorption/desorption, XRD, Raman, TEM–EDX, XPS, H2-TPR and CO chemisorption. The results of XRD, TEM–EDX and CO chemisorption characterizations showed that Re component had an effect on promoting the dispersion of Ru species on the surface of SiO2, and the measurements of H2-TPR revealed that the co-existence of Re and Ru components on SiO2 changed the respective reduction behavior of Re or Ru alone. High pre-reduction temperatures would decrease the activities of Ru–Re/SiO2 and Ru/SiO2 catalysts, compared with the corresponding calcined catalysts (without pre-reduction), which actually went through an in-situ reduction during the reaction. XPS analysis indicated that Ru species was in Ru0 metal state, while Re species was mostly in Re oxide state in the spent Ru–Re/SiO2 sample. Re component was probably in rhenium oxide state rather than Re0 metal state to take part in the reaction via interaction with Ru0 metal. 相似文献
6.
CMK-3 carbon was used as a catalyst support for Ru catalyst for ammonia decomposition. The supports were treated with acid, and the effects of treatment on the properties of CMK-3 supports were studied by N2 adsorption, XRD, XPS and mass titration. The chemical treatment of carbon support cause significant changes in carbon surface chemistry and in turn had significant effects on both catalyst dispersion and catalytic activity. It is found that the as-synthesized CMK-3 carbon is not a good catalyst support for this reaction. However, surface functional groups produced by acid treatments led to larger Ru catalyst particles, while alkali treatments made the Ru catalyst dispersion even worse due to the residue alkali or earth alkali metals. Interestingly, relatively larger Ru catalyst particles but still well dispersed in the channel of the mesoporous structures of the carbon improves NH3 conversion into H2. This is determined by the chemical reaction rate-limiting step of ammonia decomposition. The catalytic activity follows the order: Ru-K/CMK-3 > Ru-Na/CMK-3 > Ru-Ca/CMK-3 > Ru-Cl/CMK-3 > Ru-SO4/CMK-3 > Ru-PO4/CMK-3 > Ru/CMK-3 > Ru-Li/CMK-3. CMK-3 is not a good carbon catalyst support due to its amorphous structure resulting in the poor electron conductivity. 相似文献
7.
Cecilia R. Lederhos Pablo C. L’Argentière Fernando Coloma-Pascual Nora S. Fígoli 《Catalysis Letters》2006,110(1-2):23-28
The 1-heptyne selective hydrogenation carried out at 150 kPa, and at 283 and 303 K using Ru/Al2O3 and Ru/C as catalysts, was studied. Catalysts were prepared by the incipient wetness impregnation technique using RuCl3 as precursor. Ru/Al2O3 was treated in hydrogen at 373 or 573 K and Ru/C only at the last temperature. Catalysts were characterized by hydrogen chemisorption,
TPR and XPS. Ru dispersion after treatment in hydrogen at the highest temperature is similar for both catalysts. Ru is present
as Ru0 in Ru/C, while Ru0 and Ru electron-deficient species are present on the catalysts surface after hydrogen treatment at the two temperatures using
Al2O3 as support. The best catalytic behavior was observed for the highest temperature of hydrogen treatment and for 303 K reaction
temperature. As a consequence of a shape selectivity effect of the C support, the best conversion is obtained with the alumina
supported catalyst. 相似文献
8.
Saburo Hosokawa Yukihiro Hayashi Seiichiro Imamura Kenji Wada Masashi Inoue 《Catalysis Letters》2009,129(3-4):394-399
Ceria colloidal particles with a mean crystallite size of 2 nm were synthesized by a solvothermal reaction. The Ru/CeO2 catalyst prepared from the CeO2 colloids exhibited higher activity than the catalyst prepared from Ce(NO3)3. Temperature-programmed reduction analysis indicated that the reduction of surface Ce4+ was accelerated by highly dispersed Ru species on the CeO2 particles and occurred at low temperatures. The single component CeO2 sample prepared by the coagulation of the CeO2 colloid was more easily reduced and re-oxidized than the CeO2 sample prepared by the precipitation method from Ce(NO3)3. The higher activity of Ru/CeO2 prepared from the CeO2 colloids came from the inherent nature of the CeO2 support itself. 相似文献
9.
Steam reforming of toluene as a model of aromatics was performed over various Ru/12SrO–7Al2O3 (S12A7) catalysts, and the effects of Ru precursor, calcination and pre-treatment conditions on the catalytic activity and durability of Ru/S12A7catalysts were investigated. The catalytic activity of prepared Ru/S12A7 catalysts exhibited higher than that of a commercial Ru/Al2O3 (RA), despite low Ru loading. The catalysts prepared by the physical mixing of Ru (PPh3)3Cl2 and S12A7 (PPH) had higher catalytic activities than the catalysts prepared by the impregnation with RuCl3 nH2O (CL). It is interesting that the N2 pre-treated PPH and CL catalysts especially had higher catalytic activities than the H2 pre-treated PPH and CL catalysts. In their catalysts, there was a linear relationship between the catalytic activity and the Ru dispersion estimated by CO chemisorption. The catalytic activity of the N2 pre-treated PPH catalyst has little decreased with time on stream, whereas the catalytic activities of the N2 pre-treated CL catalyst and H2 pre-treated PPH catalyst gradually decreased with time on stream. 相似文献
10.
Long Zhao Jinghong Zhou Hong Chen Mingguang Zhang Zhijun Sui Xinggui Zhou 《Korean Journal of Chemical Engineering》2010,27(5):1412-1418
Carbon nanofiber (CNFs) supported Ru catalysts for sorbitol hydrogenolysis to ethylene glycol and propylene glycol were prepared
by incipient wetness impregnation, calcination and reduction. The effect of calcination on catalyst properties was investigated
using thermal gravimetry analysis, temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy,
transmission electron microscopy and N2 physisorption. The results indicated that calcination introduced a great amount of surface oxygen-containing groups (SOCGs)
onto CNF surface and induced the phase transformation of Ru species, but slightly changed the texture of Ru/CNFs. The catalytic
performance in sorbitol hydrogenolysis showed that Ru/CNFs catalyst calcined at 240 °C presented the highest glycol selectivities
and reasonable glycol yields. It was believed that the inhibition and confinement effect of SOCGs around Ru particles as well
as the high dispersion of Ru particles was the key factor for the catalytic activity. 相似文献
11.
《Catalysis Today》2000,55(1-2):45-49
The catalytic activity for oxidation of CO by O2 was investigated on commercial Pt/C, Pt-Ru/C (Pt/Ru atomic ratio = 20, 3, 1, 1/3) and Ru/C. All samples contained 20 wt.% metal. Assuming equal surface and bulk composition, the number of surface Pt and Ru atoms was calculated from the average size of the supported metal particle as determined by TEM. On Pt-Ru/C alloys, the turnover frequency per Ru atom, NRu/molecules s−1 Ru-atom−1, was independent of chemical composition. This finding suggests that the active site in these alloys is Ru. In the temperature range 300–400 K, the turnover frequency per active metal atom was 50–300 times higher on Pt-Ru/C than on Pt/C. The turnover frequency was 400 times higher on Ru/C than on Pt/C at 313 K and 90 times higher at 353 K. Addition of water vapor to the reactant mixture left the catalytic activity of Ru/C unchanged but slightly increased the activity of Pt/C. On both catalysts the activation energy and reaction orders were nearly the same as in dry atmosphere. Conversely, the addition of water markedly decreased the activation energy for Pt-Ru(1 : 1)/C alloy (from 19 to 11 kcal mol−1). These findings suggest that fuel cells equipped with Pt-Ru/C anodes perform better than cells with Pt/C anodes. They do so because Ru effectively oxidizes the carbon monoxide present as an impurity in the H2-reformed fuel. 相似文献
12.
13.
Ammonia synthesis reaction was performed over a novel ruthenium catalyst supported on perovskite-type BaTiO3. It was quite worth noting that Ru/BaTiO3 catalyst exhibited outstanding activity for ammonia synthesis. The results of XRD, CO2-TPD, H2-TPR and TEM indicated that the strong metal–support interaction (SMSI) between a partially reduced support and Ru combined with strong basicity of support was responsible for such high catalytic activity. The electrons could be easily transferred from the support to the surface of Ru particles by the SMSI effect facilitated the cleavage of NN and greatly enhanced the activity for ammonia synthesis. 相似文献
14.
《Catalysis communications》2009,10(15):2489-2495
Ru/Al2O3, Ru/C and Ru/ZrO2 catalysts were applied to the hydrogenolysis of glycerol to propanediol, and the effect of Re as an additive on the catalytic performance of Ru catalysts was examined. The catalyst systems were characterized by N2 adsorption/desorption, XRD, TEM-EDX and XPS. The hydrogenolysis of glycerol was carried out under the conditions of 120–180 °C, 4–10 MPa hydrogen pressure and 4–8 h, and the conversion of glycerol varied from 18.7% to 29.7% over Ru/Al2O3, Ru/C and Ru/ZrO2 catalysts. The reaction results indicate that Re possesses high promoting effect on the catalytic performance of Ru catalysts in glycerol hydrogenolysis. 相似文献
15.
Abigail Rose Yangdong Qian Peter P. Wells Jun Yao Fred Mosselmans 《Electrochimica acta》2007,52(18):5556-5564
Ruthenium modified carbon supported platinum catalysts have been shown to have a similar activity towards carbon monoxide oxidation as conventionally prepared bimetallic PtRu alloy catalysts. In this study the effect of the applied electrode potential and potential cycles on the location and oxidation state of the Ru species in such Ru modified Pt/C catalysts was investigated using in situ EXAFS collected at both the Ru K and Pt L3 absorption edges. The as prepared catalyst was found to consist of a Pt core with a Ru oxy/hydroxide shell. The potential dependent data indicated alloying to form a PtRu phase at 0.05 V versus RHE and subsequent dealloying to return to the Ru oxy/hydroxide decorated Pt surface at potentials greater than 0.7 V. The Ru-O distances obtained indicate that both Ru3+ and Ru4+ species are present on the surface of the Pt particles at oxidising potentials; the former is characteristic of the as prepared Ru modified Pt/C catalyst and following extensive periods at potentials above 0.7 V and the latter of the Ru oxide species on the PtRu alloy. 相似文献
16.
Dipak D. Payal 《Chemical Engineering Communications》2018,205(5):657-666
Effluents from the pharmaceutical and dye industries contain chlorinated organic pollutants. The effective treatment of such effluents constitutes a challenging task. In this work, 4-chlororesorcinol (PCRE) and 4-chloro-2-aminophenol (PCAP) were selected as model chloro-organic compounds. Catalytic hydrodechlorination (HDC) of PCRE and PCAP in the aqueous phase was investigated in a slurry reactor using commercial carbon supported ruthenium catalyst. HDC reactions of PCRE and PCAP were studied over the ranges in temperature, 313–353?K, H2 partial pressure, 0.69–2.76?MPa, and catalyst loading, 0.2–1.2?kg/m3. The performance of Ru/C catalyst for hydrodechlorination and ring saturation was promising. The kinetic data were modeled using Langmuir–Hinshelwood–Hougen–Watson kinetics. The HDC reaction of PCRE and PCAP using Ru/C catalyst proceeds via a dual-site mechanism, wherein atomic H2 reacts with the adsorbed organic substrate. The activation energy for the hydrodechlorination reactions of PCRE and PCAP was 41.6 and 49.4?kJ/mol, respectively. 相似文献
17.
Highly ordered Ru-containing mesoporous carbons (Ru-OMC) were for the first time synthesized by a one-pot method. Comparing with our previously reported Ir-OMC, the Ru precursor must be added after the formaldehyde was consumed by polycondensation with resorcinol to obtain a small particle size. The resultant Ru-OMC samples with different Ru contents were characterized with X-ray diffraction (XRD), N2 adsorption-desorption, and Transmission electron microscopy (TEM). The results evidenced the formation of highly ordered mesostructure, in which Ru particles were imbedded. The new carbon materials were further evaluated in the selective hydrogenation of cinnamaldehyde (CMA). By comparison with the traditional Ru/AC catalyst, our Ru-OMC samples exhibited much higher activity (2–14-fold) and up to 60% of selectivity to cinnamyl alcohol (CMO). 相似文献
18.
《Catalysis communications》2003,4(9):471-476
Catalytic wet air oxidation of a representative organic compound (aqueous solution of 5 g l−1 succinic acid at 190 °C and 50 bar total air pressure) was investigated over gold on titania prepared from the deposition–precipitation method (with urea or NaOH) and compared to experiments performed over a Ru/TiO2 catalyst. These preliminary results demonstrate that gold catalysts are efficient for the degradation of this organic acid. The catalytic activity is strongly dependent on the gold particle size characterized by transmission electron microscopy (TEM) with smaller particles producing higher turnover frequencies. Modification of metal dispersion occurs during reaction, leading to minor activity. 相似文献
19.
钌基氨合成催化剂氢氮吸附性能的研究 总被引:1,自引:0,他引:1
The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and nitrogen, dispersion of metallic Ru and catalytic activity of active carbon (AC) supported ruthenium catalyst for ammonia synthesis have been studied by means of pulse chromatography, temperature-programmed desorption, and activity test. Promoters K, Ba and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly, and particularly, potassium exhibited the best promotion on the activity because of the strong electronic donation to metallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or triple promoters. The activity of Ru/AC catalyst is dependent on the adsorption of hydrogen and nitrogen. The high activity of catalyst could be ascribed to strong dissociation of nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit the adsorption of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by Sm2O3 shows the best dispers 相似文献
20.
《Catalysis communications》2011,16(1):23-26
A series of Ru/Sm2O3–CeO2 catalysts were prepared by using a co-precipitation (CP) method and characterized by XRD, BET, SEM, H2-TPD-MS, H2-TPR and CO chemisorption. The activity test shows that ammonia concentration of the catalyst with 7% Sm is 13.4% at 10 MPa, 10,000 h− 1, 425 °C, which is 21% higher than that of Ru/CeO2. Such high catalytic activity was due to three effects: the morphology changes of catalyst, electrodonating property of partially reduced CeO2 − x to Ru metal and the property of easily hydrogen desorption derived from the presence of Sm3+ in ceria. 相似文献