共查询到20条相似文献,搜索用时 15 毫秒
1.
F.E. Lpez-Surez A. Bueno-Lpez M.J. Illn-Gmez. 《Applied catalysis. B, Environmental》2008,84(3-4):651-658
Cu/Al2O3 catalysts with metal loading from 0.64 to 8.8 wt.% have been prepared and characterized by different techniques: N2 adsorption at −196 °C (BET surface area), ICP (Cu loading), XRD, selective copper surface oxidation with N2O (Cu dispersion), TPR-H2 (redox properties), and XPS (copper surface species). The catalytic activity for soot oxidation has been tested both in air and NOx/O2. The activity in air depends on the amount of easily-reduced Cu(II) species, which are reduced around 275 °C under TPR-H2 conditions. The amount of the most active Cu(II) species increases with the copper loading from Cu_1% to Cu_5% and remains almost constant for higher copper loading. In the presence of NOx, the first step of the mechanism is NO oxidation to NO2, and the catalytic activity for this reaction depends on the copper loading. For catalysts with copper loading between Cu_1% and Cu_5%, the catalytic activity for soot oxidation in the presence of NOx depends on NO2 formation. For catalysts with higher copper loading this trend is not followed because of the low reactivity of model soot at the temperature of maximum NO2 production. Regardless the copper loading, all the catalysts improve the selectivity towards CO2 formation as soot oxidation product both under air and NOx/O2. 相似文献
2.
Aqueous-phase reforming of ethylene glycol over supported Pt and Pd bimetallic catalysts 总被引:3,自引:0,他引:3
George W. Huber John W. Shabaker Steven T. Evans James A. Dumesic 《Applied catalysis. B, Environmental》2006,62(3-4):226-235
More than 130 Pt and Pd bimetallic catalysts were screened for hydrogen production by aqueous-phase reforming (APR) of ethylene glycol solutions using a high-throughput reactor. Promising catalysts were characterized by CO chemisorption and tested further in a fixed bed reactor. Bimetallic PtNi, PtCo, PtFe and PdFe catalysts were significantly more active per gram of catalyst and had higher turnover frequencies for hydrogen production (TOFH2) than monometallic Pt and Pd catalysts. The PtNi/Al2O3 and PtCo/Al2O3 catalysts, with Pt to Co or Ni atomic ratios ranging from 1:1 to 1:9, had TOFH2 values (based on CO chemisorption uptake) equal to 2.8–5.2 min−1 at 483 K for APR of ethylene glycol solutions, compared to 1.9 min−1 for Pt/Al2O3 under similar reaction conditions. A Pt1Fe9/Al2O3 catalyst showed TOFH2 values of 0.3–4.3 min−1 at 453–483 K, about three times higher than Pt/Al2O3 under identical reaction conditions. A Pd1Fe9/Al2O3 catalyst had values of TOFH2 equal to 1.4 and 4.3 min−1 at temperatures of 453 and 483 K, respectively, and these values are 39–46 times higher than Pd/Al2O3 at the same reaction conditions. Catalysts consisting of Pd supported on high surface area Fe2O3 (Nanocat) showed the highest turnover frequencies for H2 production among those catalysts tested, with values of TOFH2 equal to 14.6, 39.1 and 60.1 min−1 at temperatures of 453, 483 and 498 K, respectively. These results suggest that the activity of Pt-based catalysts for APR can be increased by alloying Pt with a metal (Ni or Co) that decreases the strengths with which CO and hydrogen interact with the surface (because these species inhibit the reaction), thereby increasing the fraction of catalytic sites available for reaction with ethylene glycol. The activity of Pd-based catalysts for APR can be increased by adding a water-gas shift promoter (e.g. Fe2O3). 相似文献
3.
The La1−xKxMnO3 perovskite-type oxides whose sizes were in nanometric range were prepared by the citric acid-ligated method. The structures of these perovskite-type oxides were examined by XRD and FT-IR. The catalytic activity for the combustion of soot particulate was evaluated by a technique of the temperature-programmed reaction. In the LaMnO3 catalyst, the partial substitution of K for La at A-site enhanced the catalytic activity for the combustion of soot particle. In the La1−xKxMnO3 catalysts, the combustion temperature of soot particle decreases with increasing x values. The La1−xKxMnO3 oxides with the substitution quantity between x=0.20 and x=0.25 are good candidate catalysts for the soot particle removal reaction, and the combustion temperature of soot particle is between 285 and 430 °C when the contact of catalysts and soot is loose, and their catalytic activities for the combustion of soot particle are as good as supported Pt catalysts, which is the best catalyst system so far reported for soot combustion under loose contact conditions. 相似文献
4.
Beatriz Miranda Eva Díaz Salvador Ordez Fernando V. Díez 《Catalysis communications》2006,7(12):945-949
The performance of 0.5% Ru/Al2O3 for the deep oxidation of trichloroethene (1000–2500 ppmV, WHSV = 55 h−1) in air was studied in this work. Experiments were carried out both at dry and wet (20,000 ppmV of H2O) conditions. Catalytic performance was studied in terms of activity and selectivity for the different reaction products (CO2, HCl, Cl2, C2Cl4, CCl4 and CHCl3). Both the activity and the selectivity for total combustion are higher than other catalysts suggested in the literature for this process (especially Pd and Pt).The main organic by-products are CCl4 and CHCl3, whereas in all the other catalysts tested in the literature, tetrachloroethene is the main organic by-product. This fact suggests that the mechanism of the combustion reaction, involving a double-bond scission, is essentially specific for this catalyst.Kinetic data was fit to a pseudo-first order kinetic expression, providing fairly good fit. 相似文献
5.
A number of nano-gold catalysts were prepared by depositing gold on different metal oxides (viz. Fe2O3, Al2O3, Co3O4, MnO2, CeO2, MgO, Ga2O3 and TiO2), using the homogeneous deposition precipitation (HDP) technique. The catalysts were evaluated for their performance in the combustion of methane (1 mol% in air) at different temperatures (300–600 °C) for a GHSV of 51,000 h−1. The supported nano-gold catalysts have been characterized for their gold loading (by ICP) and gold particle size (by TEM/HRTEM or XRD peak broadening). Among these nano-gold catalysts, the Au/Fe2O3 (Au loading = 6.1% and Au particle size = 8.5 nm) showed excellent performance. For this catalyst, temperature required for half the methane combustion was 387 °C, which is lower than that required for Pd(1%)/Al2O3 (400 °C) and Pt(1%)/Al2O3 (500 °C) under identical conditions. A detailed investigation on the influence of space velocity (GHSV = 10,000–100,000 cm3 g−1 h−1) at different temperatures (200–600 °C) on the oxidative destruction of methane over the Au/Fe2O3 catalyst has also been carried out. The Au/Fe2O3 catalyst prepared by the HDP method showed much higher methane combustion activity than that prepared by the conventional deposition precipitation (DP) method. The XPS analysis showed the presence of Au in the different oxidation states (Au0, Au1+ and Au3+) in the catalyst. 相似文献
6.
Dalia Angeles-Wedler Katrin Mackenzie Frank-Dieter Kopinke 《Applied catalysis. B, Environmental》2009,90(3-4):613-617
Pd-based catalysts have become important in environmental catalysis for their ability to hydrodechlorinate a wide range of chlorinated organic contaminants in water under ambient conditions. The success of their application in the remediation practice, e.g. for groundwater treatment, is often hindered by the sensitivity of Pd to poisoning by sulphur compounds. In this study, the stability and sulphide-induced deactivation behaviour of a highly active Pd/Al2O3 catalyst was investigated. The specific activity of Pd for the hydrodechlorination of chlorobenzene corresponds to rate coefficients up to kPd = 350 L g−1 min−1. The totally deactivated catalyst, resultant of sulphide poisoning, was regenerated with potassium permanganate. The pH value, as a key parameter which may influence the degree of deactivation as well as the efficiency of catalyst regeneration, was evaluated. Results show that in clean water the Pd/Al2O3 catalyst showed no inherent deactivation regardless of the ageing time and the pH value of the catalyst suspension. The degree of catalyst poisoning effected by 1.8–5.4 μM sulphide, corresponding to molar ratios of S:Pdsurface = 1.5–8.5, was observed to be higher under neutral and alkaline than under acidic conditions. The exposure of the catalyst to higher sulphide concentration of 14.2 μM resulted in complete catalyst deactivation regardless of the pH conditions. However, the efficacy of permanganate as oxidative regenerant for the fouled catalyst showed strong pH-dependence. A regeneration time of 10–30 min at low pH was sufficient to recover completely the high catalytic activity of Pd/Al2O3 for the hydrodechlorination reaction. 相似文献
7.
Chunshan Li Daisuke Hirabayashi Kenzi Suzuki 《Applied catalysis. B, Environmental》2009,88(3-4):351-360
Newly synthesized nickel calcium aluminum catalysts (Ni/Ca12Al14O33) were tested in a fixed bed reactor for biomass tar steam reforming, toluene as tar destruction model compound. Four catalysts (Ni/Ca12Al14O33) were prepared with Ni loading amount from 1, 3, 5 to 7 wt%, even 1% loading catalyst also showed excellent performance. Catalysts aged experiments in the absence (60 h on stream) and presence of H2S were characterized by BET, X-ray diffraction (XRD), and Raman spectra. It was observed that Ni/Ca12Al14O33 showed excellent sustainability against coke formation due to the “free oxygen” in the catalysts. It also exhibited higher H2S-poisoning resistance property compared to the commercial catalysts Ni/Al2O3 (5%) and Ni/CaO0.5/MgO0.5. Raman spectra revealed that “free oxygen O2− and O22−” in the structure of the catalysts could be substituted by sulfur then protected Ni poisoning on some degree, but reactivation experiments by O2 flowing showed that the sulfide Ni/Ca12Al14O33 was difficult to completely restore, incorporation of sulfur in the structure only partly regain by O2. The kinetic model proposes, as generally accepted, a first-order reaction for toluene with activation energy of 82.06 kJ mol−1 was coincident with the literature data. The Ni/Ca12Al14O33 catalyst was effective and relative cheap, which may be lead to reduction in the cost of hot gas cleaning process. 相似文献
8.
V. Matsouka M. Konsolakis R.M. Lambert I.V. Yentekakis 《Applied catalysis. B, Environmental》2008,84(3-4):715-722
The nature and relative populations of adsorbed species formed on the surface of un-promoted and sodium-promoted Pt catalysts supported either on bare Al2O3 or CeO2/La2O3-modified Al2O3, were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) under simulated automobile exhaust conditions (CO + NO + C3H6 + O2) at the stoichiometric point. The DRIFT spectra indicate that interaction of the reaction mixture with the Pt/Al2O3 catalyst leads mainly to formation of formates and acetates on the support and carbonyl species on partially positively charged Pt atoms (Ptδ+). Although enrichment of Al2O3 with lanthanide elements (CeO2 and La2O3) does not significantly modify the carboxylate species formed on the support, it causes significant modification of the oxidation state of Pt, as indicated by the appearance of a substantial population of carbonyl species on reduced Pt sites (Pt0–CO). This modification of the Pt component is enhanced when Na-promotion is used, leading to formation of carbonyl species only on electron enriched Pt (i.e., fully reduced Pt0 sites) and to the formation of NCO on these Pt entities (2180 cm−1). The latter are thought to result from enhanced NO dissociation at Na-modified Pt sites. These results correlate well with observed differences in the catalytic performance of the three different systems. 相似文献
9.
This paper presents some important results of the studies on preparation and catalytic properties of nanodispersed Au/Al2O3 catalysts for low-temperature CO oxidation, which are carried out at the Boreskov Institute of Catalysis (BIC) starting from 2001. The catalysts with a gold loading of 1–2 wt.% were prepared via deposition of Au complexes onto different aluminas by means of various techniques (“deposition-precipitation” (DP), incipient wetness, “chemical liquid-phase grafting” (CLPG), chemical vapor deposition (CVD)). These catalysts have been characterized comparatively by a number of physical methods (XRD, TEM, diffuse reflectance UV/vis and XPS) and catalytically tested for combustion of CO impurity (1%) in wet air stream at near-ambient temperature. Using the hydroxide or chloride gold complexes capable of chemical interaction with the surface groups of alumina as the catalyst precursors (DP and incipient wetness techniques, respectively) produces the catalysts that contain metallic Au particles mainly of 2–4 nm in diameter, uniformly distributed between the external and internal surfaces of the support granules together with the surface “ionic” Au oxide species. Application of organogold precursors gives the supported Au catalysts of egg shell type which are either close by mean Au particle size to what we obtain by DP and incipient wetness techniques (CVD of (CH3)2Au(acac) vapor on highly dehydrated Al2O3 in a rotating reactor under static conditions) or contain Au crystallites of no less than 7 nm in size (CLPG method). Regardless of deposition technique, only the Cl-free Au/Al2O3 catalysts containing the small Au particles (di ≤ 5 nm) reveal the high catalytic activity toward CO oxidation under near-ambient conditions, the catalyst stability being provided by adding the water vapor into the reaction feed. The results of testing of the nanodispersed Au/Al2O3 catalysts under conditions which simulate in part removal of CO from ambient air or diesel exhaust are discussed in comparison with the data obtained for the commercial Pd and Pt catalysts under the same conditions. 相似文献
10.
A series of MnOx–CeO2 mixed oxide catalysts with different compositions prepared by sol–gel method were tested for the catalytic combustion of chlorobenzene (CB), as a model of volatile organic compounds of chlorinated aromatics. MnOx–CeO2 catalysts with different ratios of Mn/Ce + Mn were found to possess high catalytic activity in the catalytic combustion of CB, and MnOx(0.86)–CeO2 was identified as the most active catalyst, on which the temperature of complete combustion of CB was 254 °C. Effects of systematic variation of reaction conditions, including space velocity and inlet CB concentration on the catalytic combustion of CB were investigated. Additionally, the stability and deactivation of MnOx–CeO2 catalysts were studied by various characterization methods and other assistant experiments. MnOx–CeO2 catalysts with high Mn/Ce + Mn ratios present a stable high activity, which is related to their high ability to remove the adsorbed Cl species and a large amount of active surface oxygen. 相似文献
11.
A series of samples of La–Cr–O– perovskites were designed as catalysts for diesel soot combustion. They were prepared by using co-precipitation method, at ambient temperature using ammonia followed by a hydrothermal treatment (T = 200 °C, P = 20 atm, t = 24 h). All the chromium-containing precursors were then calcined at high temperature to develop the oxide catalyst. Two phase composition 86%LaCrO3–(14%) La2CrO6 or 94%LaCrO3–6%La2O3 were formed depending on the atmosphere of calcination (oxygen or hydrogen respectively) used. Their respective BET surface areas were 1.1 and 6.5 m2 g−1. Highly crystalline, pure phase of LaCrO3 and La2CrO6 powders were also prepared, with BET area of 4 and 3 m2 g−1, respectively. The crystalline structure and properties of all samples were characterised by X-ray diffraction (XRD), using Rietveld refinement, and temperature-programmed reduction (TPR) techniques. O2-TPD measurements performed on all samples showed the presence of suprafacial, weakly chemisorbed oxygen only for LaCrO3, which contributes actively to soot combustion. TPR study performed on all catalysts showed that while pure LaCrO3 and La2O3 samples did not reduce, the biphasic catalysts showed the presence of oxygen depletion peaks characteristic of lattice oxygen mobility in the samples at ca. 665 °C. Catalytic combustion of diesel soot was studied over all catalysts. The results showed that pure LaCrO3 exhibited significant catalytic activity which was sensitively affected by the modifier La2CrO6 or La2O3. 相似文献
12.
Jong-Woo Jeong Byungchul Choi Myung Taeck Lim 《Journal of Industrial and Engineering Chemistry》2008,14(6):830-835
Catalytic oxidation activity of carbon-black (CB) simulating the soot of diesel particulate matters to CO2 over 3Pt/Al2O3, 3Pt5Mn/Al2O3 and 3Pt/30Ba–Al2O3 catalysts is investigated with model gases of diesel emission. In case of the large amount of CB compared to the amount of catalyst (3/1, w/w) in the mixture sample, insufficient oxygen at the point of sudden increase in the amount of CO2 is leaded to the partial oxidation using the lattice oxygen of the catalyst. And the peaks of CO2 after the first peak were attributed to the regional combustion of the CB, which was not in contact with catalyst particles. The fresh 3Pt5Mn was estimated to the oxidation states on the catalyst surface by XPS. For used sample at 700 °C, the BEs of Pt 4d5 was revealed to metallic state Pt(0) (314.4 eV) in a predominant levels compared with Pt(II) (317.3 eV). While BEs of Mn 2p were similar to that obtained from the fresh 3Pt5Mn. It is suggested that Pt is in charge of the roles in CB-oxidation, using the lattice oxygen of the catalyst. Two-stage catalytic system with the strategies of promoting the soot oxidation and NOx reduction, simultaneously, were composed of the CB oxidation catalyst and the diesel oxidation catalyst. The catalytic oxidation of CB was accelerated by activated oxidants and exothermic reaction resulted from the diesel oxidation catalyst, which lies in upstream of two-stage. But the system with the CB oxidation catalyst sited in the upstream showed the initiation of CB oxidation at a lower temperature than the other case. Two-stage catalytic system composed of 3Pt5Mn with CB in the upstream and DOC in the downstream showed high oxidation activity with 95% consumption rate of CB to the total loaded CB in the range of 100–500 °C during the TPR process. 相似文献
13.
D. Mescia J.C. Caroca N. Russo N. Labhsetwar D. Fino G. Saracco V. Specchia 《Catalysis Today》2008,137(2-4):300
Nano-structured perovskite-type lanthanum ferrites La1 − xAxFe1 − yByO3 (where A = Na, K, Rb and B = Cu), prepared by the solution combustion synthesis (SCS) method and characterized by BET, XRD, FESEM, AAS and catalytic activity tests in microreactors as well as on an engine bench, proved to be effective in the simultaneous removal of soot and NO, the two prevalent pollutants in diesel exhaust gases in the temperature range 350–450 °C. The best compromise between soot and nitrogen oxide abatement was shown by the La-K-Cu-FeO3 catalyst which displayed the highest catalytic activity towards carbon combustion and the highest NO conversion activity. 相似文献
14.
M. Zawadzki W. Walerczyk F.E. López-Suárez M.J. Illán-Gómez A. Bueno-López 《Catalysis communications》2011,12(13):1238-1241
Mesoporous and nanosized cobalt aluminate spinel with high specific surface area was prepared using microwave assisted glycothermal method and used as soot combustion catalyst in a NOx + O2 stream. For comparison, zinc aluminate spinel and alumina supported platinum catalysts were prepared and tested. All samples were characterised using XRD, (HR)TEM, N2 adsorption–desorption measurements. The CoAl2O4 spinel was able to oxidise soot as fast as the reference Pt/Al2O3 catalyst. Its catalytic activity can be attributed to a high NOx chemisorption on the surface of this spinel, which leads to the fast oxidation of NO to NO2. 相似文献
15.
Solid superacid catalysts including SO42−/ZrO2 (SZ), rare earth (RE) oxide-promoted SZ and RE oxides together with alumina-promoted SZ were prepared. Their catalytic performances in the esterification reaction of ethanol and acetic acid were investigated. The textural property, crystalline phase and surface acidity of the prepared catalysts were characterized by using nitrogen adsorption–desorption isotherms, X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy of pyridine adsorption techniques, respectively. Effects of the reaction time and catalyst reuse cycle as well as catalyst regeneration on the catalytic behaviors were studied. Experimental results showed that Yb2O3–Al2O3 promoted SZ (designated as SZAY) catalyst exhibited an optimal esterification performance; the Lewis acid sites with moderate and super strong strength could mainly be responsible for the esterification reaction; and doping both Yb2O3 and Al2O3 on SZ not only boosted the esterification activity but also alleviated catalyst deactivation resulted from the surface sulfur loss by solvation. 相似文献
16.
In this work we report results of NOx adsorption and diesel soot combustion on a noble metal promoted K/La2O3 catalyst. The fresh-unpromoted solid is a complex mixture of hydroxide and carbonate compounds, but the addition of Rh favors the preferential formation of lanthanum oxycarbonate during the calcination step. K/La2O3 adsorbs NOx through the formation of La and K nitrate species when the solid is treated in NO + O2 between 70 and 490 °C. Nitrates are stable in the same temperature range under helium flow. However, they become unstable at ca. 360 °C when either Rh and/or Pt are present, the effect of Rh being more pronounced. Nitrates decompose under different atmospheres: NO + O2, He and H2. The effect of Rh might be to form a thermally unstable complex (Rh–NO+) which takes part both in the formation of the nitrates when the catalyst is exposed to NOx and in the nitrates decomposition at higher temperatures. Regarding soot combustion, nitrates react with soot with a temperature of maximun reaction rate of ca. 370 °C, under tight contact conditions. This temperature is not affected by the presence of Rh, which indicates that the stability of nitrates has little effect on their reaction with soot. 相似文献
17.
Thermal behavior of crude oil (Fosterton) asphaltenes mixed with reservoir sand was investigated using thermogravimetric analysis (TGA), in nitrogen and air atmospheres for different heating rates up to 800 °C. In this study, four sets of TGA runs were performed to examine the thermal behavior of Fosterton asphaltenes and the coke derived from the asphaltenes. The parameters studied were heating rate (10, 15 and 20 °C min− 1) and the type of purge gas (N2 and air) employed for the process of thermal degradation of asphaltenes. Distributed activation energy model (DAEM) has been applied to study the asphaltene pyrolysis kinetics. It was observed that the activation energy was distributed from 46.16 to 72.17 kJ/mol, for the conversion range of 0.1 to 0.4. The general model for nth order reaction was used to obtain the kinetic parameters of coke oxidation reaction from the TGA data. From the model, the calculated activation energy, E, was 93.46 kJ/mol and the pre-exponential factor was 9.59 × 105 min− 1 for the coke combustion. The apparent order of combustion reaction gradually increased from 0.7 to 0.8 for different temperatures. 相似文献
18.
M. Kaneeda H. Iizuka T. Hiratsuka N. Shinotsuka M. Arai 《Applied catalysis. B, Environmental》2009,90(3-4):564-569
The present work has been undertaken to tailor Pt/Al2O3 catalysts active for NO oxidation even after severe heat treatments in air. For this purpose, the addition of Pd has been attempted, which is less active for this reaction but can effectively suppress thermal sintering of the active metal Pt. Various Pd-modified Pt/Al2O3 catalysts were prepared, subjected to heat treatments in air at 800 and 830 °C, and then applied for NO oxidation at 300 °C. The total NO oxidation activity was shown to be significantly enhanced by the addition of Pd, depending on the amount of Pd added. The Pd-modified catalysts are active even after the severe heat treatment at 830 °C for a long time of 60 h. The optimized Pd-modified Pt/Al2O3 catalyst can show a maximum activity limited by chemical equilibrium under the conditions used. The bulk structures of supported noble metal particles were examined by XRD and their surface properties by CO chemisorption and EDX-TEM. From these characterization results as well as the reaction ones, the size of individual metal particles, the chemical composition of their surfaces, and the overall TOF value were determined for discussing possible reasons for the improvement of the thermal stability and the enhanced catalytic activity of Pt/Al2O3 catalysts by the Pd addition. The Pd-modified Pt/Al2O3 catalysts should be a promising one for NO oxidation of practical interest. 相似文献
19.
J. Yang V. Tschamber D. Habermacher F. Garin P. Gilot 《Applied catalysis. B, Environmental》2008,83(3-4):229-239
The goal of this paper was to make the link between sintering of a 1.6% Pt/Al2O3 catalyst and its activity for CO oxidation reaction. Thermal aging of this catalyst for different durations ranging from 15 min to 16 h, at 600 and 700 °C, under 7% O2, led to a shift of the platinum particle size distributions towards larger diameters, due to sintering. These distributions were studied by transmission electron microscopy. The number and the surface average diameters of platinum particles increase from 1.3 to 8.9 nm and 2.1 to 12.8 nm, respectively, after 16 h aging at 600 °C. The catalytic activity for CO oxidation under different CO and O2 inlet concentrations decreases after aging the catalyst. The light-off temperature increased by 48 °C when the catalyst was aged for 16 h at 600 °C. The CO oxidation reaction is structure sensitive with a catalytic activity increasing with the platinum particle size. To account for this size effect, two intrinsic kinetic constants, related either to platinum atoms on planar faces or atoms on edges and corners were defined. A platinum site located on a planar face was found to be 2.5 more active than a platinum site on edges or corners, whatever the temperature. The global kinetic law {r (mol m−2 s−1) = 103 × exp(−64,500/RT)[O2]0.74[CO]−0.5)} related to a reaction occurring on a platinum atom located on planar faces allows a simulation of the CO conversion curves during a temperature ramp. Modeling of the catalytic CO conversion during a temperature ramp, using the different aged catalysts, allows prediction of the CO conversion curves over a wide range of experimental conditions. 相似文献
20.
Pt–W and Pt–Mo based catalysts were evaluated for methane combustion using a sandwich-type microreactor. Alumina washcoated microchannels were impregnated with platinum in combination with and promoted with tungsten and molybdenum and compared with commercially available Pt/Al2O3 catalysts. Catalysts were tested in the range of 300–700 °C with flow rates adjusted to GHSV of 74,000 h−1 and WHSV of 316 L h−1 g−1. Catalysts containing tungsten were found to be the most active and the most stable possibly due to a metal interaction effect. A Pt–W/γ-Al2O3 containing 4.6 wt% Pt and 9 wt% W displayed the highest activity with full conversion at 600 °C and a selectivity to CO2 of 99%. 相似文献