共查询到20条相似文献,搜索用时 31 毫秒
1.
Ki Baek Kim Min Kyu Kim Yun Ha Kim Kwang Sup Song Eun Duck Park 《Research on Chemical Intermediates》2010,36(6-7):603-611
We prepared Pd catalysts supported on various metal oxides, viz. γ-Al2O3, α-Al2O3, SiO2–Al2O3, SiO2, CeO2 and TiO2 by an incipient wetness method and applied them to propane combustion. Several techniques: N2 physisorption, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), CO chemisorption, temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO) were employed to characterize the catalysts. Pd/SiO2–Al2O3 showed the least catalytic activity at high temperatures among Pd catalysts supported on irreducible metal oxides, viz. SiO2, Al2O3 and SiO2–Al2O3. Pd/γ-Al2O3 was much superior for this reaction to Pd/α-Al2O3. The Pd catalyst supported on reducible metal oxides (CeO2 and TiO2) with a less specific surface area showed the higher catalytic activity compared with that supported on reducible metal oxides with a higher specific surface area, even though the former had a less Pd dispersion than the latter. In the case of Pd/SiO2–Al2O3, the initially reduced Pd catalyst was superior to the fully oxidized one. The oxidation of metallic Pd occurred in the presence of O2 with increasing reaction temperature, which resulted in the change in the catalytic activity. 相似文献
2.
S. Scire R. Maggiore S. Galvagno C. Crisafulli L. Solarino 《Reaction Kinetics and Catalysis Letters》1989,40(2):349-356
Addition of Sn modifies the catalytic performance of Pt/ZSM-5. Total conversions decrease with increasing Sn/Pt ratio. Selectivity to aromatics is higher on the Pt–Sn samples. A Pt–Sn interaction has been confirmed by H2 chemisorption and TPR experiments.
Sn Pt/ZSM5. Sn/Pt . Pt–Sn. Pt–Sn H2 .相似文献
3.
Ring opening of ethylcyclopentane (ECP) was studied over 6.3% Pt/SiO2 (EUROPT-1) and 10% Pt/Al2O3, as a function of the hydrogen pressure. Both catalysts gave almost nonselective ring opening. Pt/Al2O3 produced also olefins, more side dealkylation and less fragmentation products. It is likely, that adlineation sites are operative over both catalysts.
6,3% Pt/SiO2 (EUROPT-1) 10% Pt/Al2O3, . . Pt/Al2O3 . , .相似文献
4.
Le Ngoc Xuyen Hoang Dang Lanh Ho Si Thoang J. V?lter 《Reaction Kinetics and Catalysis Letters》1989,39(2):293-298
Pt–Ni/-Al2O3 catalysts have been prepared and studied in n-hexane dehydrocyclization. The selectivity for benzene and toluene, a chain lengthening product formation was improved by Ni and correlated with its content.
Pt–Ni/-Al2O3 -. Ni . Ni , .相似文献
5.
载体对负载型NiSn催化剂丙烷脱氢性能的影响 《燃料化学学报》2017,45(12):1529-1536
研究了载体对负载型Ni Sn催化剂丙烷脱氢性能的影响,主要对比考察了以Si O2、Mg O、Al2O3、Mg Al2O4为载体的Ni Sn催化剂的丙烷脱氢性能。采用X射线衍射技术(XRD)、氮气吸附-脱附技术、氨气程序升温脱附技术(NH3-TPD)以及氢气程序升温还原技术(H2-TPR)对催化剂样品进行表征。结果表明,Si O2因具有较大的比表面积、大孔径、酸性较弱等特点,以其为载体制备所得催化剂中Ni2.67Sn2组分含量高,催化剂性能较高。 相似文献
6.
Kazuhisa Murata Isao Takahara Megumu Inaba 《Reaction Kinetics and Catalysis Letters》2008,93(1):59-66
Solid acid supports such as H-ZSM5, H-Mordenite, γ-Al2O3, USY and Beta catalysts were modified with Pt. These Pt/oxide catalysts were found to be active for propane formation through
aqueous reforming of glycerol in the presence of hydrogen. The reforming reactions, possibly, proceeded through reaction cycles
of dehydration on acid sites and hydrogenation on Pt sites over the catalysts. 相似文献
7.
负载型钯催化剂上生物质气化气催化燃烧 总被引:2,自引:0,他引:2
采用浸渍法制备了Pd/Al2O3、Pd/Ce/Al2O3、Pd/Mn/Al2O3、Pd/La/Al2O3四种催化剂。并借助XRD、BET对催化剂相结构、比表面积、孔结构进行了表征,在固定床反应器上考察了四种催化剂对CO、H2和CH4的催化燃烧性能。结果表明,随着La、Ce、Mn离子的引入使得催化剂的比表面积和孔容积不断降低;添加助剂Ce可以提高催化剂活性和热稳定性,助剂La可以提高催化剂的抗烧结能力,而助剂Mn在低温时可以提高催化剂活性,但并不能抑制催化剂的高温钝化。CO和H2的起燃顺序随催化剂的不同而不同,但四种催化剂对CO和H2的催化燃烧活性接近,均可以在低温条件下迅速燃烧,同时其燃烧特征温度明显低于CH4。 相似文献
8.
Milan Králik Zuzana Vallušová Peter Major Adriana Takáčová Milan Hronec Dana Gašparovičová 《Chemical Papers》2014,68(12):1690-1700
Liquid phase hydrogenation of chloronitrobenzene isomers (x-CNB x = 2, 3, 4) to the corresponding chloroanilines (x-CAN) at mild reaction conditions (0.6 MPa, 25°C, diethyl ether-methanol as solvents) over palladium and platinum catalysts containing 1 mass % of metal on trimethylammonium functionalized poly{styrene-co-divinylbenzene} (Dowex-D) was studied. The average selectivities to x-CAN over Pd/D-Cl and Pd/D-OH catalysts were 72 % and 42 %, respectively, at the x-CNB conversion of about 80 %. The average selectivities of 81 % and 84 % were achieved using Pt/D-Cl and Pt/D-OH, respectively, at the x-CNB conversion of approximately 90 %, whereas the average starting reaction rates were 1.2 × 10?3 mol g?1 s?1 and 2.6 × 10?3 mol g?1 s?1 (hydrogen consumption rate per mass of platinum), respectively. Under similar reaction conditions, using palladium catalysts supported on a resin with anionic groups anchored to polymeric chains at the average reaction rate equal to 3.8 × 10?3 mol g?1 s?1 (hydrogen consumption rate per mass of palladium), the selectivities from 85 % (2-CAN and 3-CAN) to 95 % (4-CAN) were achieved (Kratky et al., 2002). 相似文献
9.
McCarty JG Malukhin G Poojary DM Datye AK Xu Q 《The journal of physical chemistry. B》2005,109(6):2387-2391
An essential property of combustion catalysts is long-term (>8000 h) stability at high temperatures in an environment (approximately 1 atm of both oxygen and water vapor) that aggressively promotes sintering of the supporting oxide and coarsening of the active component. Extrapolation of accelerated coarsening rate measurements, determined from shorter exposures at higher temperatures, can be made with more confidence if the physical processes of the coarsening and sintering processes were well understood. The current work examines in detail the coarsening of a high-weight-loaded palladium catalyst supported by silica-stabilized alumina at 900 degrees C in such an aggressive environment. The results of this investigation showed that the Pd particle size distribution was consistently log-normal for time periods from 100 to 4000 h, the mean particle growth rate was roughly inverse second-order in mean particle diameter, and the support not only sintered but also underwent phase transformation. The results implicate both coalescence and Ostwald ripening as important coarsening processes. 相似文献
10.
考察了整体式担载型Pt基催化剂上国产3号航空煤油(RP-3)的常压裂解反应,着重探讨了添加BaO和SrO助剂对裂解效果的影响,以及裂解时间对积炭量的影响.采用全自动吸附仪、程序升温还原、X射线光电子能谱以及X射线衍射和扫描电镜等方法对催化剂进行了表征.结果表明,在整体式担载型Pt基催化剂上RP-3裂解的总产气量比热裂解提高了39.7%;BaO或SrO助剂的添加又使其总产气量又分别提高了25.6%和37.0%;同时添加BaO和SrO的催化剂,其催化裂解总产气量则提高了96.5%.BaO和SrO助剂均可有效地抑制积炭的生成,而两者间的协同作用,进一步抑制了RP-3催化裂解过程中积炭的生成. 相似文献
11.
M. A. Aramendía V. Borau C. Jiménez J. M. Marinas F. Rodero M. E. Sempere 《Reaction Kinetics and Catalysis Letters》1992,46(2):305-312
In this work we studied and compared the catalytic activity of various supported Pt systems on the gas-phase hydrogenation of o-, m- and p-xylene. We analyzed the influence of different catalyst preparation variables (solvent, precursor, salt, support and catalyst reduction temperature used) on the catalytic activity and selectivity towards the corresponding cis-and trans-dimethylcyclohexanes.
- o-, m- -. (, , ) - -.相似文献
12.
Decomposition of methomyl over supported iron catalysts 总被引:1,自引:0,他引:1
Andjelka Tomaevi Goran Bokovi Duan Mijin Ern E. Kiss 《Reaction Kinetics and Catalysis Letters》2007,91(1):53-59
Catalytic wet peroxide oxidation of methomyl over Fe-ZSM-5 and AlFe-pillared montmorillonite was carried out at room temperature,
in a glass batch reactor, under constant airflow and halogen lamp light. Both catalysts have shown significant activity in
the degradation reaction of methomyl at a concentration of 1.0×10−4 mol. 相似文献
13.
镍基催化剂上乙醇水蒸气重整反应的研究 总被引:1,自引:1,他引:0
考察了载体对Ni催化剂乙醇水蒸气重整制氢反应性能的影响。结果表明,Ni/CeO2催化剂具有较好的低温活性和氢气选择性。对Ni担载量和焙烧温度考察发现,400℃焙烧的15%NiCeO2催化剂具有较好的催化性能;继续升高焙烧温度引起NiO和CeO2粒子的显著增大,导致对氢气选择性的降低。较小的Ni和CeO2粒子有利于乙醇水汽重整反应的进行,而大的粒子倾向于乙醇的分解反应。 350℃时,在反应过程中分别添加CO、CO2和CH4的结果表明没有发生CO和CO2甲烷化反应,而发生了一定程度的CH4水汽重整反应。 相似文献
14.
Lignier P Morfin F Mangematin S Massin L Rousset JL Caps V 《Chemical communications (Cambridge, England)》2007,(2):186-188
The gold reference catalyst Au/TiO(2) exhibits high activity in the stereoselective epoxidation of trans-stilbene in methylcyclohexane in the presence of 5 mol% TBHP, by taking part in a chain reaction involving the activation of molecular oxygen by a radical produced from methylcyclohexane. 相似文献
15.
N. Lingaiah N. Seshu Babu Rajesh Gopinath P. Siva Sankara Reddy P. S. Sai Prasad 《Catalysis Surveys from Asia》2006,10(1):29-39
The use of supported Pd catalysts, with low and high metal content, for the hydrodechlorination of chlorobenzene is presented in this article. Application of microwave irradiation during preparation of catalysts resulted in the synthesis of large Pd particles at moderate temperatures. The nature of the support played a key role in the formation of cationic Pd species. The extent of interaction of the Pd species with the support, the nature of metal precursor, particularly the residual chlorine on the surface were found to significantly affect the activity of the catalysts. In the case of bimetallic catalysts also microwave heating resulted in creation of bigger particles of Pd compared to those observed in conventionally heated catalysts. Besides, it minimized alloy formation as a result of which the activity of the catalysts in hydrodechlorination was found to be higher compared to that observed on conventionally prepared catalysts. Contrary to the general observation that low dispersed Pd catalysts are preferable for high stability, by means of the deposition-precipitation method adopted for catalyst preparation it was demonstrated that even highly dispersed (low Pd containing) catalysts can exhibit comparable activity and stability. An analysis of the nature of Pd species and its role in the stability of the catalysts is presented.IICT communication No. 051224 相似文献
16.
M. A. Aramendia V. Borau J. F. Gomez C. Jimenez J. M. Marinas 《Reaction Kinetics and Catalysis Letters》1986,30(2):337-344
In this work we have carried out a study on the liquid phase hydrogenation of benzylideneaniline, using dihydrogen over various supported Pd catalysts. Benzyl-ideneaniline reduction can be classified as insensitive to the catalyst structure. On the other hand, no compensating effect has been observed in performing the reaction over different supported Pd catalysts.
Pd , . . Pd , .相似文献
17.
18.
B. N. Kuznetsov V. I. Kovalchuk A. A. Efremov N. I. Bakhmutova L. D. Palagai V. I. Zaikovskii 《Reaction Kinetics and Catalysis Letters》1987,34(2):451-456
Modifying effect of phosphorus on the catalytic activity of supported Pt and Pt–Fe catalysts for CO hydrogenation has been studied. Phosphorus-containing compounds decrease significantly the methane yield with increasing yield of C2–C7 hydrocarbons.
CO Pt- Pt–Fe-. , C2–C7.相似文献
19.
《Journal of Energy Chemistry》2017,26(1):200-206
Wormholelike mesoporous carbons(WMCs) with three different pore diameters(D_p),namely WMC-F7(D_p=8.5nm),WMC-F30(D_p=4.4nm),and WMC-FO(D_p = 3.1nm) are prepared via a modified sol-gel process.Then PtRu nanoparticles with the particle size(d_(Pt)) of ~3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method.It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction.PtRu/WMC-F7 with Dp 2d_(Pt) exhibits the largest electrochemical surface area(ESA) and the highest activity toward methanol electrooxidation.With the decrease in D_p,PtRu/WMC-F30 and PtRu/WMC-FO have much lower ESA and electrochemical activity,especially for the isopropanol electrooxidation with a larger molecular size.When D_p is more than twice d_(Pt),the mass transfer of reactants and electrolyte are easier,and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced. 相似文献
20.
Re/Sibunite is a more active and selective catalyst for hydrogenation of ethyl acetate to ethanol under elevated temperatures
and hydrogen pressures than Re/θ-Al2O3 and Re/γ-Al2O3. The activity of the catalyst is increased on replacing NH4ReO4 with HReO4 and treatment of the support with a 13% solution of HNO3.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1006–1008, May, 1999. 相似文献