Preparation of Thin Palladium Composite Membranes and Application to Hydrogen/Nitrogen Separation

薄钯合成的膜被修改无电的 plating 方法与高氢流动在氧化铝支持和稠密的 Pd/-Al2O3 合成的膜上准备，为氢的好选择被获得。它在氮上为氢渗入和氢选择在一个单个煤气的浸透系统被测试。相应的膜的氢渗入象 2.45 ×一样高 10 ? 6mol · m ? 2 · s ? 1 · Pa ? 1 并且在 623K 和 0.1MPa 的压力差别的超过 700 的 H2/N2 选择。到 H2 浸透的合成的膜的主要抵抗躺在铝陶器的支持而非薄 Pd 层。

Lanthanum Modified Ni/γ-Al_2O_3 Catalysts for Partial Oxidation of Methane

La modified Ni/T-Al2O3 catalysts prepared by co-precipitation method using NaOH-Na2CO3 as a precipitator show high activity and selectivity for the partial oxidation of methane （POM）. Meanwhile, the addition of La is beneficial for the formation of an active component and stability of support. We investigated some factors including calcining temperature, nickel content, and space velocity, which turned out to have a strong influence on catalytic activity and selectivity. By XRD and TPR, it is concluded that Ni^0 reduced from amorphous NiAl2O4 is the major active component for POM.

A highly selective catalyst of Co/La_(4)Ga_(2)O_(9) for CO_(2) hydrogenation to ethanol

A new catalyst of Co/La_(4)Ga_(2)O_(9) for CO_(2) hydrogenation to produce ethanol was prepared by reducing LaCo^(0).5 Ga0.5 O3,which showed excellent selectivity to ethanol(%35 C-mol%)at mild reaction conditions(270°C,3.5 MPa,3000 m L g-1 h-1).The catalysts were characterized by N_(2) adsorption/desorption,XRD,XAFS,CO and CO_(2)-TPD,H2 chemisorption,XPS and TEM techniques.The interaction between Co nanoparticles(NPs)and La2+4 Ga_(2)O_(9) oxide resulted in Co^(0)-Coon the surface of Co NPs.It was proposed that La_(4)Ga_(2)O_(9) could catalyze reverse water gas shift reaction(r-WGS),which converted CO_(2) to CO.Then,the CO migrated to Co^(0)-Co^(2+)on Co NPs,where it was hydrogenated to form ethanol like higher alcohols synthesis from syngas.The results suggest that by controlling the oxidation state of cobalt,and combined with a kind of active site for activating CO_(2) to form CO,a catalyst with excellent selectivity to ethanol could be obtained for CO_(2) hydrogenation,which means that the complex reaction may be proceed with high selectivity using only one active metal component.

NiO-Ce_(0.5)Zr_(0.5)O_2 catalysts prepared by citric acid method for steam reforming of ethanol

NiO-Ce0.5Zr0.5O2 催化剂被柠檬酸盐方法准备并且从乙醇(SRE ) 改过的蒸气为氢生产使用了。催化表演上的镍内容和空间速度的效果被调查。准备催化剂与 XRD 和热分析技术被描绘。20%NiO-Ce0.5Zr0.5O2 催化剂为经由 SRE，在乙醇， 100% 的变换能被获得与的氢生产很活跃、选择喂 20% 的部件(H2O+EtOH ) 和 80% N2，在在 350 点的臼齿的比率的 3/1 的水 /

Dehydrogenation of isobutane to isobutene over a Pt-Cu bimetallic catalyst in the presence of LaAlO_(3) perovskite

In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,including XRD,N_(2) adsorptiondesorption,TEM,XPS,H2TPR and TG.The results show that the existence of LaAlO_(3) perovskite can enhance the dispersion and sintering resistance of metal nanoparticles and facilitate the transfer of carbon deposits from active sites to the support.Interestingly,the perovskite nanoparticles can also inhibit the reduction of CuOx and the formation of PtCu alloys,resulting in the suitable interaction between Pt and Cu.The PtCu/LaAlO_(3)/SiO_(2)catalyst exhibits the optimal dehydrogenation performance with an isobutane conversion of 47%and isobutene selectivity of 92%after 310 min reaction,which was ascribed to the unique role of LaAlO_(3) perovskite as well as the appropriate PtCu interaction.

Valence State of Active Copper in CuO_x/CeO_2 Catalysts for CO Oxidation

CuOx/CeO2 catalysts were prepared by adsorption-impregnation method, CO conversion was tested over the catalysts pretreated under different conditions for preferential CO oxidation in H2, and the catalysts were characterized with X-ray photoelectron spectroscopy and temperature programmed reduction. Experimental results show that there are two kinds of copper, which are Cu^＋ and Cu^2＋ in calcined CuOx/CeO2, Among them, the Cu^＋ is the key active component for CO oxidation. The main reason is as follows： CO is activated by copper for CO oxidation over CuOx/CeO2, while CO can not be activated by Cu^2＋. Only when Cu^2＋ is reduced to Cu ^＋ or Cu^0, the copper may be active for CO oxidation, moreover, the experimental results show that the reduction of Cu^2＋ does not lead to an increase of catalytic activity. So the active species is Cu^＋ in CuOx/CeO2 catalysts.

Preferential Oxidation of Carbon Monoxide in Excess Hydrogen over Au/Co_3O_4-CeO_2 Catalysts

Au/Co3O4-CeO2 mixed-oxide catalysts were shown tion of CO in hydrogen-rich mixture. Activity was markedly experimentally to be highly active and selective for the oxidainfluenced by the composition of the support, aging temperature and Au-loading temperature. It provided that single-step removal of CO from hydrogen-rich stream both in the absence and presence of CO2 and H2O to a PEMFC tolerant level. It was found that catalytic activity is greatly affected by adding CO2 in the mixture and increased by farther adding H2O. It recants H2O has the effect to rise catalytic activity. Moreover, it shows better stability with reaction time for the preferential CO oxidation.

Monolithic macroporous catalysts—a new route for miniaturization of water-gas shift reactor

Monolithic macroporous Pt/CeO2/Al2O3 catalysts were prepared using concentrated emulsions synthesis route, and the obtained samples were characterized with SEM, TG, TEM, XRD and TPR techniques. These monolithic catalysts were applied to water gas shift （WGS） reaction in reformed gases. The SEM and TEM results indicated that the monoliths possessed macroporosity, and that the platinum particles homogeneously dispersed on the supports with the particle size in the range of 1-2 nm. The reducibility of the catalysts was characterized by TPR method, and it was shown that the monolithic PtOx/CeO2/Al2O3 exhibited the similar reducibility property to that of the particle PtOx/CeO2 reported in literatures. The CO conversion over the monolithic catalysts is higher than that over micro-reactor catalysts for WGS reaction in the reformed gases conditions, indicating that the monolithic macroporous catalysts is a potential new route for miniaturization of WGS reactor.

Preferential Oxidation of CO in H_2 over CuO/CeO_2 Catalysts

A very active catalyst of CuO/CeO_2 was made by adsorption-impregnation method for preferential oxidation of CO in H_2. The CO conversion is close to 100% and selectivity to CO oxidation is 96% over this catalyst at a low reaction temperature of 95 ℃ and a space velocity of 40000 cm^3·g^(-1)·h^(-1) in the reaction mixture of 1%CO, 1%O_2, and 50%H_2 balanced with N_2. The effect of preparation conditions on catalytic performances was investigated. The catalytic performance of the CuO/CeO_2 catalysts was compared with that of other CO preferential oxidation catalysts reported in literature.

Reverse water gas shift reaction over Co-precipitated Ni-CeO_2 catalysts

The Ni-CeO2 catalysts with different Ni contents were prepared by a co-precipitation method and used for Reverse Water Gas Shift （RWGS） reaction. 2wt.%Ni-CeO2 showed excellent catalytic performance in terms of activity, selectivity, and stability for RWGS reaction. Characterizations of the catalyst samples were conducted by XRD and TPR. The results indicated that, in Ni-CeO2 catalysts, there were three kinds of nickel, nickel ions in ceria lattice, highly dispersed NiO and bulk NiO. Oxygen vacancies were formed in CeO2 lattice due to the incorporation of Ni^2＋ ions into ceria lattice. Oxygen vacancies formed in ceria lattice and highly dispersed Ni were key active components for RWGS, and bulk Ni was key active component for methanation of CO2.

Cu-Co bi-metal catalyst prepared by perovskite CuO/LaCoO_3 used for higher alcohol synthesis from syngas

Cu-Co bi-metal catalysts derived from CuO/LaCoO3 perovskite structure were prepared by one-step citrate complexing method, and the structure evolution reaction from CuO/LaCoO3 to Cu-Co2C/La202CO3 under 1-12 pretreatment was investigated by techniques of XRD, TPR and TEM. The results suggest that a much higher dispersion of copper significantly enhanced the reduction of cobalt, and a stronger interaction between copper and cobalt ions in LaCoO3 particles led to the formation of bi-metallic Cu-Co particles in the reduced catalysts and the enrichment of Co on the surface of bimetallic particles. The prepared catalysts were highly active and selective for the alcohol synthesis from syngas due to the presence of copper-modified C02C species.

Perovskite LaFeO_3 supported bi-metal catalyst for syngas methanation

LaFeO3 perovskite supported Ni and Ni-Fe catalysts were prepared and applied to methanation reaction of syngas.Two preparation methods were employed.One was one-step citrate complexing method,and the other was a two step method using citrate complexing method to produce LaFeO3 and followed by loading nickel oxide on it with impregnation.The structure evolution of the sample as prepared was investigated by XRD,TPR and TEM techniques.For the former,the chemical composites of the calcined sample are NiO-Fe2O3/LaFe1-xNix O3.After reduction and reaction of CO methanation,its composites convert to Fe-Ni@Ni/LaFeO3-La2O2CO3,in which Fe-Ni@Ni is metal particles in nano-size composed of nickel core and Fe-Ni alloy shell.For the latter,the chemical composites of the calcined sample are NiO/LaFeO3; and after reduction and reaction of CO methanation,its chemical composites change to Ni/LaFeO3.Ni/LaFeO3 catalyst is a little more active, while Fe-Ni@Ni/LaFeO3-La2O2CO3 is much more stable and shows very good resistance to carbon deposition.In this work it is aimed to show that the structure and composites of the catalysts can be tailored using perovskite-type oxide as precursor prepared with different methods and conditions.Therefore,it is a promising route to prepare supported bi-metal catalysts in nano-size for a lot of metals with desired catalytic performances.

Ceria modified three-dimensionally ordered macro-porous Pt/TiO_2 catalysts for water-gas shift reaction

Three-dimensionally ordered macro-porous （3DOM） TiO2 and ceria-modified 3DOM TiO2 supported platinum catalysts were prepared with template and impregnation methods, and the resultant samples were characterized by scanning electron microscopy（SEM）, X-ray diffractometer（XRD）, high-resolution transmission electron microscopy（HRTEM） and temperature programmed reducfion（TPR） techniques. The catalytic performances over the platinum-based catalysts were investigated for water-gas shift （WGS） reaction in a wide temperature range （180-360 ℃）. The results showed that 3DOM Pt/TiO2 catalyst exhibited obviously better catalytic performance than the corresponding non macro-porous catalyst, owing to the macro-porous structure favoring mass transfer. Addition of celia into 3DOM Pt/TiO2 led to improvement of catalytic activity. TPR and HRTEM results showed that the interaction existed between ceria and titanium oxide and addition of ceria promoted the reducibility of platinum oxide and TiO2 on the interface of platinum and TiO2 particles, which contributed to high activity of the celia modified catalysts. The results indicated that ceria-modified 3DOM Pt/TiO2 was a promising candidate of fuel cell oriented WGS catalyst.

Effect of intermediate layer on the activity and adhesion stability of metal monolith supported LaMn-hexaaluminate catalyst for methane combustion

Al2O3 and La2O3 layers were coated respectively on a FeCrAl alloy foil by a dip-coating technique and used as the second support for the active LaMnAl11O19 hexaaluminate （HA） phase in a metallic monolithic catalyst. A sample without an intermediate layer was employed for comparison. The properties and performances of the catalyst were examined with X-ray diffraction （XRD）, scanning electron microscopy （SEM）, ultrasonic vibration and thermal shock techniques. Methane catalytic combustion was performed to evaluate the activity of the catalyst. The results showed that the activity and adhesion of the HA to the alloy foil could be improved with the introduction of the intermediate layer. Al2O3 provided a strong adhesion, while La2O3 weakened the interaction between the active component and alloy foil. For the activity, the catalysts made with the two different intermediate materials also showed difference.

Cerium-modified Ni-La2O3/ZrO2 for CO2 methanation

The key point in CO2 methanation is to improve the activity at low temperature and the stability.For this purpose,a new cerium-modified Ni-La2O3/ZrO2 catalyst was prepared using La1-xCexNiO3/ZrO2 with perovskite phase as the precursor,which was obtained by citrate complexation combined with an impregnation method.The resulting catalyst was characterized through Nitrogen adsorption and desorption,X-ray diffraction (XRD),Transmission electron microscopy (TEM),Hydrogen temperature programmed reduction (H2-TPR),Temperature-programmed desorption of CO2 (CO2-TPD) and that of H2 (H2-TPD),and X-ray photoelectron spectroscopy (XPS) techniques,and the catalytic performances for CO2 methanation was investigated.Cerium modification could improve the effective activation of CO2,thus enhancing the activity at low temperature for CO2 methanation.The metal Ni nanoparticles prepared using this method were highly dispersed and showed excellent resistance to sintering,leading to very good stability,which could be attributed to the following:Ni nanoparticles could be confined by cerium-modified La2O3;La2O3could be confined by the cerium ions at the La2O3/ZrO2 interface;and the cerium ions were confined by ZrO2.

CHARACTERIZATION AND ADSORPTION PROPERTIES OF POROUS CARBON NANOFIBER GRANULES

The properties of the porous granules produced by agglomeration of catalytically grown carbon nanofibers were investigated in this work. The single pellet crushing strength of the granules is high, e.g., 1.6-2.5 MPa. They have high specific surface areas, averaging 72-141 m^2·g^-1, and the majority of their pores are mesopores or macropores. The adsorption at 298 K of benzene or phenol on the granules is much lower than that on activated carbon and depends not only on the specific surface area of the carbon material but also on the sewing structure of the granules and the morphology of the carbon nanofibers. Treatment in dilute nitric acid appreciably reduces such adsorption.

Meso-macroporous Al_2O_3 supported Ru catalysts for CO preferential oxidation in hydrogen-rich gases

Series of meso-macroporous Al2O3 supported Ru catalysts with different loadings were prepared by incipient wetness method and applied to preferential oxidation of CO in hydrogen-rich gases. N2 adsorption-desorption, SEM, XRD, TEM, CO chemisorption and H2-TPR techniques were employed to characterize the catalysts. The results indicate that Ru/Al2O3 catalysts have meso-macroporous structure, high surface area and high metal dispersion. The characterization results of XRD and CO chemisorption indicate the entry of Ru ions into Al2O3 lattice. The results of catalytic performance tests indicate that the meso-macroporous Al2O3 supported Ru catalysts for CO preferential oxidation showed good activity under high space velocity. It is proposed that the macropores in the Ru/Al2O3 catalyst favor mass transfer and mesopores help to improve the dispersion of metal, resulting in the excellent catalytic performance.

Three-dimensionally ordered macro-porous Pt/TiO_2 catalyst used for water-gas shift reaction

Three-dimensionally ordered macro-porous （3DOM） Pt/TiO2 catalysts were prepared by template and impregnation methods, and the resultant samples were characterized by using TG-DTA, XRD, SEM, TEM, and TPR techniques. The catalytic performance for water-gas shift （WGS） reaction was tested, and the influences of some conditions, such as reduction temperature of catalysts, the amount of Pt loadings and space velocity on catalytic performance were investigated. It was shown that Pt particles were homogeneously dispersed on 3DOM TiO2. The reduction of TiO2 surface was important for the catalytic performance. The activity test results showed that the 3DOM Pt/TiO2 catalysts exhibited very good catalytic performance for WGS reaction even at high space velocity, which was owing to the better mass transfer of 3DOM porous structure besides the high intrinsic activity of Pt/TiO2.

Effect of precipitants on Ni-CeO_2 catalysts prepared by a co-precipitation method for the reverse water-gas shift reaction

A series of Ni-CeO2 catalysts were prepared by co-precipitation method with Na2CO3, NaOH, and mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant, respectively. The effect of the precipitants on the catalytic performance, physical and chemical properties of Ni-CeO2 catalysts was investigated with the aid of X-ray diffraction （XRD）, Bmmaner-Emmett-Teller method （BET）, Fou- rier-transform infrared spectroscopy （FT-IR）, thermogravimetry （TG）, and H2-TPR characterizations. The Ni-CeO2 catalysts were exam- ined with respect to their catalytic performance for the reverse water-gas shift reaction, and their catalytic activities were ranked as： Ni-CeO2-CP （Na2CO3：NaOH=I：I）〉Ni-CeO2-CP（Na2CO3）〉Ni-CeO2-CP（NaOH）- Correlating to the characteristic results, it was found that the catalyst prepared by co-precipitation with mixed precipitant （Na2CO3：NaOH; 1：1 ratio） as precipitant hadthe most amount of oxygen vacancies accompanied with highly dispersed Ni particles, which made the corresponding Ni-CeO2-CP（Na2CO3：NaOH=I： 1） catalyst exhibit the highest catalytic activity. While the precipitant of Na2CO3 or NaOH resulted in less or no oxygen vacancies in Ni-CeO2 catalysts. As a result, Ni-CeO2-CP（Na2CO3） and Ni-CeO2-CP（NaOH） catalysts presented poor catalytic performance.

Influence of preparation method on performance of Ni-CeO_2 catalysts for reverse water-gas shift reaction

This study investigated 1 wt.% Ni-CeO2 catalysts that were prepared using co-precipitation, deposition-precipitation, and impregnation methods for the reverse water-gas shift （RWGS） reaction. Characterizations of the catalyst samples were conducted by Brumauer-Emmett-Teller （BET）, atomic absorption spectrophotometer （AAS）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HR-TEM） and temperature programmed reduction （TPR）. The results showed that the Ni-CeO2 catalyst prepared using the co-precipitation method exhibited the best catalytic performance. In the Ni-CeO2 catalyst prepared using co-precipitation method, a combination of highly dispersed NiO and abundant oxygen vacancies was assumed to play a crucial role in determining the catalytic activity and selectivity of the RWGS reaction.