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1.
La 2NiO 4 tubular membranes of relative density over 92% were used to separate oxygen from air and facilitate the partial oxidation of methane to H 2 and CO at 900 °C. When methane was fed into a tube of inner surface area 5.11 cm 2 at a rate of 10.5 ml/min, methane throughput conversion was 89%, CO selectivity 96%, H 2/CO ratio 1.5, and the equivalent oxygen flux was 6.8 ml/min. The surface of the La 2NiO 4 membrane exposed to CH 4 decomposed into La 2O 3 and Ni, while the surface in contact with air remained almost unchanged. It is suggested that the conversion of methane in the membrane reactor involves the reforming of methane by the H 2O and CO 2 catalyzed by nickel. 相似文献
2.
Dispersing La 2O 3 on δ- or γ-Al 2O 3 significantly enhances the rate of NO reduction by CH 4 in 1% O 2, compared to unsupported La 2O 3. Typically, no bend-over in activity occurs between 500° and 700°C, and the rate at 700°C is 60% higher than that with a Co/ZSM-5 catalyst. The final activity was dependent upon the La 2O 3 precursor used, the pretreatment, and the La 2O 3 loading. The most active family of catalysts consisted of La 2O 3 on γ-Al 2O 3 prepared with lanthanum acetate and calcined at 750°C for 10 h. A maximum in rate (mol/s/g) and specific activity (mol/s/m 2) occurred between the addition of one and two theoretical monolayers of La 2O 3 on the γ-Al 2O 3 surface. The best catalyst, 40% La 2O 3/γ-Al 2O 3, had a turnover frequency at 700°C of 0.05 s −1, based on NO chemisorption at 25°C, which was 15 times higher than that for Co/ZSM-5. These La 2O 3/Al 2O 3 catalysts exhibited stable activity under high conversion conditions as well as high CH 4 selectivity (CH 4 + NO vs. CH 4 + O 2). The addition of Sr to a 20% La 2O 3/γ-Al 2O 3 sample increased activity, and a maximum rate enhancement of 45% was obtained at a SrO loading of 5%. In contrast, addition of SO =4 to the latter Sr-promoted La 2O 3/Al 2O 3 catalyst decreased activity although sulfate increased the activity of Sr-promoted La 2O 3. Dispersing La 2O 3 on SiO 2 produced catalysts with extremely low specific activities, and rates were even lower than with pure La 2O 3. This is presumably due to water sensitivity and silicate formation. The La 2O 3/Al 2O 3 catalysts are anticipated to show sufficient hydrothermal stability to allow their use in certain high-temperature applications. 相似文献
3.
In this contribution, a commercial spherical SiO 2 was modified with different amounts of La 2O 3, and used as the support of Ni catalysts for autothermal reforming of methane in a fluidized-bed reactor. Nitrogen adsorption, XRD and H 2-TPR analysis indicated that La 2O 3-modified SiO 2 had higher surface area, strengthened interaction between Ni and support, and improved dispersion of Ni. CO 2-TPD found that La 2O 3 increased the alkalescence of SiO 2 and improved the activation of CO 2. Coking reaction (via both temperature-programmed surface reaction of CH 4 (CH 4-TPSR) and pulse decomposition of CH 4) disclosed that La 2O 3 reduced the dehydrogenation ability of Ni. CO 2-TPO, O 2-TPO (followed after CH 4-TPSR) confirmed that only part amount of carbon species derived from methane decomposition could be removed by CO 2, and O 2 in feed played a crucial role for the gasification of the inactive surface carbons. Ni/ xLa 2O 3-SiO 2 ( x = 10, 15, 30) possessed high activity and excellent stability for autothermal reforming of methane in a fluidized-bed reactor. 相似文献
4.
Mixed oxides of the general formula La 0.5Sr xCe yFeO z were prepared by using the nitrate method and characterized by XRD and Mössbauer techniques. The crystal phases detected were perovskites LaFeO 3 and SrFeO 3−x and oxides -Fe 2O 3 and CeO 2 depending on x and y values. The low surface area ceramic materials have been tested for the NO+CO and NO+CH 4+O 2 (“lean-NO x”) reactions in the temperature range 250–550°C. A noticeable enhancement in NO conversion was achieved by the substitution of La 3+ cation at A-site with divalent Sr +2 and tetravalent Ce +4 cations. Comparison of the activity of the present and other perovskite-type materials has pointed out that the ability of the La 0.5Sr xCe yFeO z materials to reduce NO by CO or by CH 4 under “lean-NO x” conditions is very satisfying. In particular, for the NO+CO reaction estimation of turnover frequencies (TOFs, s −1) at 300°C (based on NO chemisorption) revealed values comparable to Rh/-Al 2O 3 catalyst. This is an important result considering the current tendency for replacing the very active but expensive Rh and Pt metals. It was found that there is a direct correlation between the percentage of crystal phases containing iron in La 0.5Sr xCe yFeO z solids and their catalytic activity. O 2 TPD (temperature-programmed desorption) and NO TPD studies confirmed that the catalytic activity for both tested reactions is related to the defect positions in the lattice of the catalysts (e.g., oxygen vacancies, cationic defects). Additionally, a remarkable oscillatory behavior during O 2 TPD studies was observed for the La 0.5Sr 0.2Ce 0.3FeO z and La 0.5Sr 0.5FeO z solids. 相似文献
5.
Ni catalysts supported on γ-Al 2O 3, CeO 2 and CeO 2–Al 2O 3 systems were tested for catalytic CO 2 reforming of methane into synthesis gas. Ni/CeO 2–Al 2O 3 catalysts showed much better catalytic performance than either CeO 2- or γ-Al 2O 3-supported Ni catalysts. CeO 2 as a support for Ni catalysts produced a strong metal–support interaction (SMSI), which reduced the catalytic activity and carbon deposition. However, CeO 2 had positive effect on catalytic activity, stability, and carbon suppression when used as a promoter in Ni/γ-Al 2O 3 catalysts for this reaction. A weight loading of 1–5 wt% CeO 2 was found to be the optimum. Ni catalysts with CeO 2 promoters reduced the chemical interaction between nickel and support, resulting in an increase in reducibility and stronger dispersion of nickel. The stability and less coking on CeO 2-promoted catalysts are attributed to the oxidative properties of CeO 2. 相似文献
6.
Co 3O 4/CeO 2 composite oxides with different cobalt loading (5, 15, 30, 50, 70 wt.% as Co 3O 4) were prepared by co-precipitation method and investigated for the oxidation of methane under stoichiometric conditions. Pure oxides, Co 3O 4 and CeO 2 were used as reference. Characterization studies by X-ray diffraction (XRD), BET, temperature programmed reduction/oxidation (TPR/TPO) and X-ray photoelectron spectroscopy (XPS) were carried out. An improvement of the catalytic activity and thermal stability of the composite oxides was observed with respect to pure Co3O4 in correspondence of Co3O4–CeO2 containing 30% by weight of Co3O4. The combined effect of cobalt oxide and ceria, at this composition, strongly influences the morphological and redox properties of the composite oxides, by dispersing the Co3O4 phase and promoting the efficiency of the Co3+–Co2+ redox couple. The presence in the sample Co3O4(30 wt.%)–CeO2 of a high relative amount of Ce3+/(Ce4+ + Ce3+) as detected by XPS confirms the enhanced oxygen mobility. The catalysts stability under reaction conditions was investigated by XRD and XPS analysis of the used samples, paying particular attention to the Co3O4 phase decomposition. Methane oxidation tests were performed over fresh (as prepared) and thermal aged samples (after ageing at 750 °C for 7 h, in furnace). The resistance to water vapour poisoning was evaluated for pure Co3O4 and Co3O4(30 wt.%)–CeO2, performing the tests in the presence of 5 vol.% H2O. A methane oxidation test upon hydrothermal ageing (flowing at 600 °C for 16 h a mixture 5 vol.% H2O + 5 vol.%O2 in He) of the Co3O4(30 wt.%)–CeO2 sample was also performed. All the results confirm the superiority of this composite oxide. 相似文献
7.
Surface-phase ZrO 2 on SiO 2 (SZrOs) and surface-phase La 2O 3 on Al 2O 3 (SLaOs) were prepared with various loadings of ZrO 2 and La 2O 3, characterized and used as supports for preparing Pt/SZrOs and Pt/SLaOs catalysts. CH 4/CO 2 reforming over the Pt/SZrOs and Pt/SLaOs catalysts was examined and compared with Pt/Al 2O 3 and Pt/SiO 2 catalysts. CO 2 or CH 4 pulse reaction/adsorption analysis was employed to elucidate the effects of these surface-phase oxides. The zirconia can be homogeneously dispersed on SiO2 to form a stable surface-phase oxide. The lanthana cannot be spread well on Al2O3, but it forms a stable amorphous oxide with Al2O3. The Pt/SZrOs and Pt/SLaOs catalysts showed higher steady activity than did Pt/SiO2 and Pt/Al2O3 by a factor of three to four. The Pt/SZrOs and Pt/SLaOs catalysts were also much more stable than the Pt/SiO2 and Pt/Al2O3 catalysts for long stream time and for reforming temperatures above 700 °C. These findings were attributed to the activation of CO2 adsorbed on the basic sites of SZrOs and SLaOs. 相似文献
8.
Both NO decomposition and NO reduction by CH 4 over 4%Sr/La 2O 3 in the absence and presence of O 2 were examined between 773 and 973 K, and N 2O decomposition was also studied. The presence of CH 4 greatly increased the conversion of NO to N 2 and this activity was further enhanced by co-fed O 2. For example, at 773 K and 15 Torr NO the specific activities of NO decomposition, reduction by CH 4 in the absence of O 2, and reduction with 1% O 2 in the feed were 8.3·10 −4, 4.6·10 −3, and 1.3·10 −2 μmol N 2/s m 2, respectively. This oxygen-enhanced activity for NO reduction is attributed to the formation of methyl (and/or methylene) species on the oxide surface. NO decomposition on this catalyst occurred with an activation energy of 28 kcal/mol and the reaction order at 923 K with respect to NO was 1.1. The rate of N 2 formation by decomposition was inhibited by O 2 in the feed even though the reaction order in NO remained the same. The rate of NO reduction by CH 4 continuously increased with temperature to 973 K with no bend-over in either the absence or the presence of O 2 with equal activation energies of 26 kcal/mol. The addition of O 2 increased the reaction order in CH 4 at 923 K from 0.19 to 0.87, while it decreased the reaction order in NO from 0.73 to 0.55. The reaction order in O 2 was 0.26 up to 0.5% O 2 during which time the CH 4 concentration was not decreased significantly. N 2O decomposition occurs rapidly on this catalyst with a specific activity of 1.6·10 −4 μmol N 2/s m 2 at 623 K and 1220 ppm N 2O and an activation energy of 24 kcal/mol. The addition of CH 4 inhibits this decomposition reaction. Finally, the use of either CO or H 2 as the reductant (no O 2) produced specific activities at 773 K that were almost 5 times greater than that with CH 4 and gave activation energies of 21–26 kcal/mol, thus demonstrating the potential of using CO/H 2 to reduce NO to N 2 over these REO catalysts. 相似文献
9.
The influence of catalyst pre-treatment temperature (650 and 750 °C) and oxygen concentration ( λ = 8 and 1) on the light-off temperature of methane combustion has been investigated over two composite oxides, Co 3O 4/CeO 2 and Co 3O 4/CeO 2–ZrO 2 containing 30 wt.% of Co 3O 4. The catalytic materials prepared by the co-precipitation method were calcined at 650 °C for 5 h (fresh samples); a portion of them was further treated at 750 °C for 7 h, in a furnace in static air (aged samples). Tests of methane combustion were carried out on fresh and aged catalysts at two different WHSV values (12 000 and 60 000 mL g−1 h−1). The catalytic performance of Co3O4/CeO2 and Co3O4/CeO2–ZrO2 were compared with those of two pure Co3O4 oxides, a sample obtained by the precipitation method and a commercial reference. Characterization studies by X-ray diffraction (XRD), BET and temperature-programmed reduction (TPR) show that the catalytic activity is related to the dispersion of crystalline phases, Co3O4/CeO2 and Co3O4/CeO2–ZrO2 as well as to their reducibility. Particular attention was paid to the thermal stability of the Co3O4 phase in the temperature range of 750–800 °C, in both static (in a furnace) and dynamic conditions (continuous flow). The results indicate that the thermal stability of the phase Co3O4 heated up to 800 °C depends on the size of the cobalt oxide crystallites (fresh or aged samples) and on the oxygen content (excess λ = 8, stoichiometric λ = 1) in the reaction mixture. A stabilizing effect due to the presence of ceria or ceria–zirconia against Co3O4 decomposition into CoO was observed. Moreover, the role of ceria and ceria–zirconia is to maintain a good combustion activity of the cobalt composite oxides by dispersing the active phase Co3O4 and by promoting the reduction at low temperature. 相似文献
10.
The subsolidus region of the BaO–La 2O 3–V 2O 5 phase diagram has been redetermined. Previously reported binary phases of LaVO 4, La 8V 2O 17, La 3VO 7, BaLa 2O 4, Ba 3V 2O 8, Ba 2V 2O 7, Ba 3V 4O 13 and BaV 2O 6 have all been confirmed. The ternary phases Ba 2LaV 3O 11, Ba 3LaV 3O 12 and Ba 3La 40V 12O 93 have also been confirmed. The new phase “BaLa 10V 4O 26” has been synthesised for the first time and is reported here along with the amended phase diagram. The previously omitted phase of La 1.42V 0.58O 3.58 has also been included and reasons for this are cited. The diagram is shown for two temperatures (1000 and 600 °C) due to the low melting point of V 2O 5-rich compounds. 相似文献
11.
The perovskite-type oxides La 0.8Ce 0.2Cu 0.4Mn 0.6O 3 and La 0.8Ce 0.2Ag 0.4Mn 0.6O 3 prepared by reverse microemulsion and sol–gel methods (denoted as R and S, respectively), have been investigated on their catalytic performance for the (NO + CO) reaction, and characterized by means of temperature-programmed desorption (TPD), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). XRD measurements proved the presence of the perovskite phase with a considerable amount of CeO 2 phase and the formation of CeO 2 phase was restrained with the reverse microemulsion method. TEM investigations revealed that the La 0.8Ce 0.2Cu 0.4Mn 0.6O 3-R nanoparticles were uniform spheres in shape with diameters ranging from 40 to 50 nm, whereas an aggregation of particles was found for the La 0.8Ce 0.2Cu 0.4Mn 0.6O 3-S catalyst. The activity of NO reduction with CO decreased in the order of La 0.8Ce 0.2Cu 0.4Mn 0.6O 3-R > La 0.8Ce 0.2Cu 0.4Mn 0.6O 3-S > La 0.8Ce 0.2Ag 0.4Mn 0.6O 3-R > La 0.8Ce 0.2Ag 0.4Mn 0.6O 3-S. In NO-TPD experiments, the principal desorbed species detected in the effluent was NO with a trace amount of O 2 and N 2O, suggesting that the non-dissociated adsorption of NO on the surface of the perovskite-type oxides was dominant. The XPS results revealed that Ce 4+ and Cu + was the predominant oxidation state for Ce and Cu components in La 0.8Ce 0.2Cu 0.4Mn 0.6O 3 and La 0.8Ce 0.2Ag 0.4Mn 0.6O 3 catalysts. The existence of Cu + ions and its redox reaction (Cu + ↔ Cu 2+) would benefit the NO adsorption and reduction by CO. 相似文献
12.
The sintering of lime doped with up to 2 mol% La 2O 3 as well as CeO 2 was followed on firing at 1400, 1500 and 1600°C. X-ray diffraction and reflected-light microscopy techniques have been used to investigate the phase composition and texture of the fired samples. The load bearing capacity and the rate of hydration of the obtained dense lime samples have also been determined to assess its quality. It is found that doping lime with 0·5–1·0 mol% of either La 2O 3 or CeO 2 and firing up to 1600°C leads to dense and hydration-resistant lime with uniform texture. At this level of the dopant oxides, normal grain growth occurred with the increase in the degree of direct bonding. Doping with less than 0·5 mol% La 2O 3 or CeO 2 is insufficient for inhibiting the discontinuous grain growth of the lime grains. On the other hand, increase in the dopant content above 1·0 mol% showed finer grain sizes at the expense of the degree of direct bonding. 相似文献
13.
Direct nitric oxide decomposition over perovskites is fairly slow and complex, its mechanism changing dramatically with temperature. Previous kinetic study for three representative compositions (La 0.87Sr 0.13Mn 0.2Ni 0.8O 3−δ, La 0.66Sr 0.34Ni 0.3Co 0.7O 3−δ and La 0.8Sr 0.2Cu 0.15Fe 0.85O 3−δ) has shown that depending on the temperature range, the inhibition effect of oxygen either increases or decreases with temperature. This paper deals with the effect of CO 2, H 2O and CH 4 on the nitric oxide decomposition over the same perovskites studied at a steady-state in a plug-flow reactor with 1 g catalyst and total flowrates of 50 or 100 ml/min of 2 or 5% NO. The effect of carbon dioxide (0.5–10%) was evaluated between 873 and 923 K, whereas that of H 2O vapor (1.6 or 2.5%) from 723 to 923 K. Both CO 2 and H 2O inhibit the NO decomposition, but inhibition by CO 2 is considerably stronger. For all three catalysts, these effects increase with temperature. Kinetic parameters for the inhibiting effects of CO 2 and H 2O over the three perovskites were determined. Addition of methane to the feed (NO/CH 4=4) increases conversion of NO to N 2 about two to four times, depending on the initial NO concentration and on temperature. This, however, is still much too low for practical applications. Furthermore, the rates of methane oxidation by nitric oxide over perovskites are substantially slower than those of methane oxidation by oxygen. Thus, perovskites do not seem to be suitable for catalytic selective NO reduction with methane. 相似文献
14.
Reforming of methane with carbon dioxide into syngas over Ni/γ-Al 2O 3 catalysts modified by potassium, MnO and CeO 2 was studied. The catalysts were prepared by impregnation technique and were characterized by N 2 adsorption/desorption isotherm, BET surface area, pore volume, and BJH pore size distribution measurements, and by X-ray diffraction and scanning electron microscopy. The performance of these catalysts was evaluated by conducting the reforming reaction in a fixed bed reactor. The coke content of the catalysts was determined by oxidation conducted in a thermo-gravimetric analyzer. Incorporation of potassium and CeO 2 (or MnO) onto the catalyst significantly reduced the coke formation without significantly affecting the methane conversion and hydrogen yield. The stability and the lower amount of coking on promoted catalysts were attributed to partial coverage of the surface of nickel by patches of promoters and to their increased CO 2 adsorption, forming a surface reactive carbonate species. Addition of CeO 2 or MnO reduced the particle size of nickel, thus increasing Ni dispersion. For Ni–K/CeO 2–Al 2O 3 catalysts, the improved stability was further attributed to the oxidative properties of CeO 2. Results of the investigation suggest that stable Ni/Al 2O 3 catalysts for the carbon dioxide reforming of methane can be prepared by addition of both potassium and CeO 2 (or MnO) as promoters. 相似文献
16.
Four different β-Si 3N 4 ceramics with silicon oxynitrides [Y 10(SiO 4) 6N 2, Yb 4Si 2N 2O 7, Er 2Si 3N 4O 3, and La 10(SiO 4) 6N 2, respectively] as secondary phases have been fabricated by hot-pressing the Si 3N 4–Re 4Si 2N 2O 7 (Re=Y, Yb, Er, and La) compositions at 1820°C for 2 h under a pressure of 25 MPa. The oxidation behavior of the hot-pressed ceramics was characterized and compared with that of the ceramics fabricated from Si 3N 4–Re 2Si 2O 7 compositions. All Si 3N 4 ceramics investigated herein showed a parabolic weight gain with oxidation time at 1400°C and the oxidation products of the ceramics were SiO 2 and Re 2Si 2O 7. The Si 3N 4–Re 4Si 2N 2O 7 compositions showed inferior oxidation resistance to those from Si 3N 4–Re 2Si 2O 7 compositions, owing to the incompatibility of the secondary phases of those ceramics with SiO 2, the oxidation product of Si 3N 4. Si 3N 4 ceramics from a Si 3N 4–Er 4Si 2N 2O 7 composition showed the best oxidation resistance of 0·198 mg cm −2 after oxidation at 1400°C for 192 h in air among the compositions investigated herein. 相似文献
17.
Palladium (Pd) supported on CeO 2-promoted γ-Al 2O 3 with various CeO 2 (ceria) crystallinities, were used as catalysts in the methane steam reforming reaction. X-ray diffraction (XRD) analysis, FTIR spectroscopy of adsorbed CO, and X-ray photoelectron spectroscopy (XPS) were employed to characterize the samples in terms of Pd and CeO 2 structure and dispersion on the γ-Al 2O 3 support. These results were correlated with the observed catalytic activity and deactivation process. Arrhenius plots at steady-state conditions are presented as a function of CeO 2 structure. Pd is present on the oxidized CeO 2-promoted catalysts as Pd 0, Pd + and Pd 2+, at ratios strongly dependent on CeO 2 structure. XRD measurements indicated that Pd is well dispersed (particles <2 nm) on crystalline CeO 2 and is agglomerated as large clusters (particles in 10–20 nm range) on amorphous CeO 2. FTIR spectra of adsorbed CO revealed that after pre-treatment under H 2 or in the presence of amorphous CeO 2, partial encapsulation of Pd particles occurs. CeO 2 structure influences the CH 4 steam reforming reaction rates. Crystalline CeO 2 and dispersed Pd favor high reaction rates (low activation energy). The presence of CeO 2 as a promoter conferred high catalytic activity to the alumina-supported Pd catalysts. The catalytic activity is significantly lower on Pd/γ-Al 2O 3 or on amorphous (reduced) CeO 2/Al 2O 3 catalysts. The reaction rates are two orders of magnitude higher on Pd/CeO 2/γ-Al 2O 3 than on Pd/γ-Al 2O 3, which is attributed to a catalytic synergism between Pd and CeO 2. The low rates on the reduced Pd/CeO 2/Al 2O 3 catalysts can be correlated with the loss of Pd sites through encapsulation or particle agglomeration, a process found mostly irreversible after catalyst regeneration. 相似文献
18.
It is shown that introduction of additives of rare-earth element oxides (La 2O 3, CeO 2) enables regulating the structural and functional characteristics of Pd/Al 2O 3-catalysts (applied on ceramic monoliths of honeycomb structure) of nitrogen oxide reduction by methane. Modifying additives provide increase of thermal stability of porous structure of both highly dispersed Al 2O 3, as the second support, and the catalyst as a whole. Contribution of La2O3 and CeO2 in increasing the thermal stability is of an additive nature, and lanthanum oxide shows the higher efficiency than cerium one. According to X-ray phase analysis data, stabilizing action is conditioned by occurrence of rare-earth element oxides into lattice of Al2O3, which retards diffusional processes leading to phase transitions of low-temperature crystalline modifications of alumina into high-temperature ones with a low specific surface. For the catalyst samples modified with La2O3 an effect of thermal activation is observed, which is revealed by increase in catalytic activity as a result of annealing at 850 °C. Such a phenomenon, as shown by means of X-ray photoelectron spectroscopy technique, can be explained via stabilization of palladium in singly charged state in the form of groups of Pd+O2− and corresponding increase in concentration of active centers. 相似文献
19.
Coupled semiconductor (CS) Cu/CdS–TiO 2/SiO 2 photocatalyst was prepared using a mutli-step impregnation method. Its optical property was characterized by UV–vis spectra. BET, XRD, Raman and IR were used to study the structure of the photocatalyst. Fine CdS was found dispersed over the surface of anatase TiO 2/SiO 2 substrate. Chemisorption and IR analysis showed methane absorbed in the molecular state interacted weakly with the surface of catalyst, and the interaction of CO 2 with CS produced various forms of absorbed CO 2 species that were primarily present in the form of formate, bidentate and linear absorption species. Photocatalytic direct conversion of CH 4 and CO 2 was performed under the operation conditions: 373 K, 1:1 of CO 2/CH 4, 1 atm, space velocity of 200 h −1 and UV intensity of 20.0 mW/cm 2. The conversion was 1.47% for CH 4 and 0.74% for CO 2 with a selectivity of acetone up to 92.3%. The reaction mechanisms were proposed based on the experimental observations. 相似文献
20.
A series of novel dense mixed conducting ceramic membranes based on K 2NiF 4-type (La 1–xCa x) 2 (Ni 0.75Cu 0.25)O 4+δ was successfully prepared through a sol-gel route. Their chemical compatibility, oxygen permeability, CO and CO 2 tolerance, and long-term CO 2 resistance regarding phase composition and crystal structure at different atmospheres were studied. The results show that higher Ca contents in the material lead to the formation of CaCO 3. A constant oxygen permeation flux of about 0.63 mL·min −1·cm −2 at 1173 K through a 0.65 mm thick membrane was measured for (La 0.9Ca 0.1) 2 (Ni 0.75Cu 0.25)O 4+δ, using either helium or pure CO 2 as sweep gas. Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO 2 concentration. The membrane showed excellent chemical stability towards CO 2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature. In addition, this membrane did not deteriorate in a high-energy CO 2 plasma. The present work demonstrates that this (La 0.9Ca 0.1) 2(Ni 0.75Cu 0.25)O 4+δ membrane is a promising chemically robust candidate for oxygen separation applications. 相似文献
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