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Fiber glass supported catalysts and pure platinum: laser ignition of catalytic combustion of propane
A pure platinum (Pt) catalyst and a new industrial catalyst, the silica fiber glass catalyst (SFGC) doped with only 0.2% Pt, were studied and compared. For propane–air catalytic combustion, the ignition of the reaction and its stability were investigated. The reaction, ignited by a laser beam, propagated as a wave front with constant amplitude and velocity along both catalysts, 10 mm/s for Pt, and 1–2 mm/s for SFGC. Laser ignition thresholds and the parameter space for front propagation were determined for both catalysts. Spatial instability (resulting in the destruction of the homogeneous regime of combustion and in the formation of hot spots) was found for Pt, but not for SFGC. The new catalyst (SFGC) containing only 10–3 of Pt has the same catalytic activity as pure Pt and better spatial stability. 相似文献
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以ZSM-5分子筛、铝溶胶、硝酸钯、硝酸铂和水为原料制备分子筛浆料,采用真空抽提-一次涂覆法在堇青石蜂窝陶瓷载体表面制备出PdxPty-ZSM-5/Cordierite整体式催化剂,考察了Pd负载量、ZSM-5分子筛的硅铝比和Pd/Pt质量比对整体式催化剂的丙烷催化燃烧性能的影响,并用超声波振荡、SEM、XRD、H2-TPR和C3H8-TPD等手段对整体式催化剂进行了表征。当球磨时间为60 min,分子筛浆料固含量为38%时,整体式催化剂的涂层上载量可达到178 g?L-1,涂层脱落率低于0.5%。Pd2Pt3-ZSM-5/Cordierite整体式催化剂(贵金属总负载量为1.2 g?L-1)对于丙烷的催化燃烧具有较好的催化活性(T50=259℃,T90=323℃)和稳定性,具有良好的工业应用前景,其中较低的ZSM-5分子筛硅铝比以及Pd和Pt之间的相互作用增加了对丙烷的吸附能力和表面活性氧物种的数量,从而提高了整体式催化剂的催化活性。 相似文献
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The dehydrogenation of propane over a silica-supported vanadium oxide catalyst was investigated at 823 K under atmospheric pressure in the presence/absence of CO2. The yield of propene and the selectivity to propene were higher in the dehydrogenation in the presence of CO2 than those in the dehydrogenation in the absence of CO2. On the other hand, the yield of aromatics and the selectivity to aromatics were much higher in the dehydrogenation in the absence of CO2 than those in the dehydrogenation in the presence of CO2. TPR measurements, NH3 desorption studies and in-situ UV–vis studies on the catalyst were also performed to elucidate the effects of CO2 on the behavior of the vanadium oxide in the catalyst during the dehydrogenation of propane. 相似文献
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The ammoxidation of propane to acrylonitrile was investigated over various multicomponent mixed oxidecatalysts. Bi3GaMo2 oxide, Bi0.85V0.55Mo0.45 oxide and Bi2TiMo oxide showed a good selectivity to acrylonitrile. The catalytic performance was strongly dependent on the components constituting the oxides due to the concentration of defects, the nature of the component and the mixed oxide phases. The effect of support type on the catalytic performance of Bi0.85V0.55Mo0.45 oxide showed that selectivity to acrylonitrile decreased in the order silica > alumina > magnesia. The catalytic performance of Bio0.85V0.55Mo0.45 oxide was improved by the addition of a small amount of a component such as magnesium, calcium and tellurium. The catalytic performance of Bi3GaMo2, oxide catalyst, however, decreased significantly with the addition of a smallamount of alkali metal (Li, Na, K, Cs). 相似文献
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Electrochemical promotion of the oxidation of propane on Pt/YSZ and Rh/YSZ catalyst-electrodes 总被引:1,自引:0,他引:1
The effect of electrochemical promotion (EP) or non-faradaic electrochemical modification of catalytic activity (NEMCA) was
studied in the catalytic reaction of the total oxidation of propane on Pt and Rh films deposited on Y2O3-stabilized-ZrO2 (or YSZ), an O2− conductor, in the temperature range 420–520 °C. In the case of Pt/YSZ and for oxygen to propane ratios lower than the stoichiometric
ratio it was found that the rate of propane oxidation could be reversibly enhanced by application of both positive and negative
overpotentials (“inverted volcano” behavior), by up to a factor of 1350 and 1130, respectively. The induced rate increase
Δr exceeded the corresponding electrochemically controlled rate I/2F of O2− transfer through the solid electrolyte, resulting in absolute values of the apparent faradaic efficiency Λ=Δr/(I/2F) up to 2330. The Rh/YSZ system exhibited similar EP behavior. Abrupt changes in the oxidation state of the rhodium catalyst,
accompanied by changes in the catalytic rate, were observed by changing the O2 to propane ratio and catalyst potential. The highest rate increases, by up to a factor of 6, were observed for positive overpotentials
with corresponding absolute values of faradaic efficiency Λ up to 830. Rate increases by up to a factor of 1.7 were observed
for negative overpotentials. The observed EP behavior is explained by taking into account the mechanism of the reaction and
the effect of catalyst potential on the binding strength of chemisorbed reactants and intermediates and on the oxidative state
of the catalyst surface. 相似文献
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Earlier studies have shown that sulfur dioxide and metal-support interaction can strongly influence propane oxidation over platinum. In particular, oxidation activity is enhanced when platinum is supported on sulfated -alumina or zirconia compared to -alumina. Therefore, it is of interest to compare the performance of palladium under the same experimental conditions. Four model catalysts were examined: Pt/-alumina, Pt/zirconia, Pd/-alumina and Pd/zirconia. The metal loading was kept at or below 0.05 wt% to emphasize changes in activity attributable to metal-support interaction. Reaction rates were measured with and without sulfur dioxide. Surface sulfation was analyzed by measuring acid strength and evaluating spectra obtained by Fourier-transform infrared spectroscopy. In contrast to platinum, sulfation does not promote propane oxidation on Pd/-alumina, and Pd/zirconia is less active than Pd/-alumina. 相似文献
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丙烷氨氧化制丙烯腈催化剂设计进展 总被引:2,自引:1,他引:1
丙烷氨氧化制丙烯腈反应工艺是潜在的具有较大经济效益的丙烯腈生产路线。介绍了丙烷氨氧化制丙烯腈催化剂的设计、催化反应机理、典型催化剂组成和结构的研究进展。 相似文献
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Propane catalytic dehydrogenation to propylene was investigated over novel platinum-based catalysts, and the BET, H2-chemisorption, H2-TPR, H2-TPD, C3H6-TPD and O2-pulse techniques were used for catalyst characterization in this paper. The results showed that the addition of Zn and Ce
promoters into Pt-based catalyst could remarkably improve the performances of dehydrogenation. Highly propylene selectivity,
about 99%, was obtained in the dehydrogenation reaction. This improvement in catalytic performances could be attributed to
the strong surface interactions, which modified the surface properties of the active platinum metal and the support, and further
improved the catalytic performance of Pt-based catalyst. 相似文献
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Several hexaaluminate-related materials were prepared via hydrolysis of alkoxide and powder mixing method for high temperature combustion of CH4 and C3H8, in order to investigate the effect of the concentration of the fuels, O2 and H2O on NOx emission and combustion characteristics. Among the hexaaluminate catalysts, Sr0.8La0.2MnAl11O19− prepared by the alkoxide method exhibited the highest activity for methane combustion and low NOx emission capability. NOx emission at 1500 °C was increased linearly with O2 concentration, whereas water vapor addition decreased NOx emission in CH4 combustion over the Sr0.8La0.2MnAl11O19− catalyst. In the catalytic combustion of C3H8 over the Sr0.8La0.2MnAl11O19− catalyst, the amount of NOx emitted was raised in the temperature range between 1000 and 1500 °C when the C3H8 concentration increased from 1 to 2 vol.%. It was found that NOx emission in this temperature range was reduced effectively by adding water vapor. 相似文献
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以L-赖氨酸为模板剂,采用沉淀法制备了BiOCl催化剂,对催化剂进行了X射线衍射、N2吸附-脱附和H2-TPR等表征,并测试了BiOCl催化剂对丙烷氧化脱氢制丙烯反应的催化性能。结果表明,制备的BiOCl催化剂为四面体结构,500 ℃焙烧3 h后,催化剂比表面积为11.2 m2·g-1,未完全还原氧物种的含量较多。随着反应温度升高,丙烷转化率和丙烯选择性增加,丙烷转化率为20%时,丙烯选择性达64.5%。 相似文献
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Zeeshan Nawaz Xiaoping Tang Qiang Zhang Dezheng Wang Wei Fei 《Catalysis communications》2009,10(14):1925-1930
The Pt–Sn-based catalyst was intensified using SAPO-34 as support for direct propane dehydrogenation to propylene. The catalyst was prepared by sequential impregnation method and characterized by XRF, BET, XRD, NH3-IR, NH3-TPD, H2-TPR, HR-TEM and O2-pulse coke analysis. NH3-TPD, IR spectra and XRD results suggested that the doping of metals on SAPO-34 did not affect its acidic strength and structural topology of support, respectively. Propylene selectivity of 94% and total olefins selectivity greater than 97% was achieved using Pt–Sn/SAPO-34. The results were compared with Pt–Sn/ZSM-5 under identical conditions. The possible reasons for improvement were the larger surface area, shape selectivity and particular by suitable acidity of SAPO-34. 相似文献