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1.
The conversions ofn-hexane and methylcyclopentane on Pt–Dy/Al2O3 containing different amounts of Dy have been investigated in a pulsed microcatalytic reactor. The poisoning effect of thiophene on the activity of Pt–Dy/Al2O3 for n-hexane conversion has been studied. The influence of Dy over Pt–Dy/Al2O3 is also discussed. 相似文献
2.
D. T. Gokak A. G. Basrur D. Rajeswar G. S. Rao K. R. Krishnamurthy 《Reaction Kinetics and Catalysis Letters》1996,59(2):315-323
Four lithium metal precursors (LiNO3, CH3COOLi, LiOH, LiCl) have been used as promoters in Pt–Sn/Al2O3 catalysts to improve activity, selectivity and stability in a modeln-decane dehydrogenation reaction. Acidity, TPR and TPCO measurements have shown that the precursors affect the acid site distribution in the support, modify the reducibility and dispersity of Pt–Sn active species, coke lay-over patterns, stability and also selectivity for formation of monoolefins in the dehydrogenation ofn-decane. 相似文献
3.
Linsheng Wang Liwu Lin Tingling Zang Hailin Cai 《Reaction Kinetics and Catalysis Letters》1994,52(1):107-111
Stabilization methods of Pt–Sn/Al2O3 dehydrogenation catalysts by modification with Sm and Li are introduced. Pt crystallite dispersion on the support can be promoted by Sm. Li, especially when corporated with Sm, very effectively inhibits carbonization and prolongs the life of the catalysts. 相似文献
4.
Metal promoted zirconia-based oxide sorbents, such as Pt–ZrO2/Al2O3 for NO
x
have been investigated. To clarify the role of the catalyst component, sorption of NO and NO2 was compared using the samples with and without Pt. The catalytic oxidation of NO to NO2 and successively to nitrate ions is an important role for the Pt catalyst. The experimental results indicate that a high-temperature calcination is essential to remove residual Cl from Pt–ZrO2–Al2O3 prepared from H2PtCl6 in order to provide more active NO
x
sorption sites. Of M–ZrO2–Al2O3 samples investigated, ruthenium as well as Pt demonstrated relatively good performance as a catalyst component in the sorbent. The FT-IR spectra after sorption of NO and NO2 demonstrated a strong band attributed to stored nitrate ions. The Pt catalyst was more resistant to sulfur poisoning than a base metal catalyst. However, the NO
x
sorptive capacities of the Pt–ZrO2/Al2O3 sorbents were expected to be deteriorated in dilute SO2 as far as observed from FT-IR spectra. 相似文献
5.
The catalytic performance and the properties of active sites on PtY/Al2O3 have been studied using a pulse microreactor, TEM and poisoning technique. The study shows that PtY/Al2O3 shows higher activity and selectivity for n-hexane conversion and the dehydrogenation of cyclohexane, as compared to Pt/Al2O3. The changes in PtY/Al2O3 geometric patterns and in both the total numbers of active sites (TNAS) and the active site distribution (ASD) caused by Y are likely to be responsible for the catalytic improvements. 相似文献
6.
T. López R. Silva V. Bertin J. Sánchez R. Gómez 《Reaction Kinetics and Catalysis Letters》1997,61(1):49-55
Tin precursor effect in Pt−Sn/Al2O3 sol-gel catalysts has been studied. It is shown that catalysts prepared with tetrabutyltin allow a better reduction of platinum
than catalysts prepared with tin tetrachloride and with tin tetra-tert-amyloxide. The solids prepared with tetrabutyltin are catalysts showing a high activity in isopropanol decomposition and
cyclohexane dehydrogenation. 相似文献
7.
Yihua Zhang Run Liu Yumei Teng Erti Fang Zhengyu Huang Xiankang Zeng 《Reaction Kinetics and Catalysis Letters》1996,58(1):91-96
A new type of catalyst from supporting C60 on MoO3 and Al2O3 has been prepared. The effect of different order of impregnation and calcination atmosphere on catalyst are investigated by the solution test in toluene, UV-VIS spectroscopy and temperature programmed reduction (TPR). The results show that when the catalyst was prepared by supporting MoO3 on C60/Al2O3 and calcined in N2, there is a stronger interaction between C60, MoO3 and Al2O3, but when supporting C60 on MoO3/Al2O3, the interaction is relatively weak. We consider that in the former method a new complex, Mo–C60–O–Al, is formed. 相似文献
8.
M. A. Ryashentseva 《Russian Chemical Bulletin》1993,42(2):387-388
Catalysts containing as little as 0.5 mass. % Pd are highly active in the dehydrogenation of cyclohexane when Sibunite® or active alumina (for gas dehumidification) are used as catalyst supports. Dehydrogenative activity of the Pd/Al2O3 catalyst is further increased upon surface sulfidation and addition of 0.25–0.5 mass. % Re.Translated fromIzvestiya Akademii Nauk. Seriya Khmicheskaya, No. 2, pp. 422–423, February, 1993. 相似文献
9.
C. Martin I. Martin V. Rives S. Damyanova A. Spojakina 《Reaction Kinetics and Catalysis Letters》1995,54(1):203-208
A correlation exists between the number of surface acid sites and the catalytic activity of NiMo/TiO2–Al2O3 systems in thiophene hydrodesulfurization. The catalytic activity for thiophene hydrodesulfurization and surface concentration of Brönsted acid sites increase with the titania content in the TiO2–Al2O3 support. 相似文献
10.
The solid state reaction of NaAlO2 with γ-Al2O3 was investigated kinetically. Powdered compacts with various compositions (Al2O3/NaAlO2 = 1–5) were fired at 700–1200°C for 1–768 hr. The amounts of the reaction product were determined by peak heights of X-ray diffraction patterns. β″-Al2O3 was formed predominantly from the sample with Al2O3/NaAlO2 = 2. The firing time for the β″-Al2O3 formation was shortened as the firing temperature was raised, and the activation energy, Ea, for formation was about 130–135 kcal/mole. The sample of Al2O3/NaAlO2 = 5 formed m-Al2O3 with the mullite structure and was observed to transform gradually to β-Al2O3. Ea for the m-Al2O3 formation and for the transition were about 55–60 and 40 kcal/mole, respectively, which resulted in Ea of about 95–100 kcal/mole for the β-Al2O3 formation. The mechanism of the m-Al2O3 formation is discussed briefly. 相似文献
11.
12.
Jifei Jia Yuan Kou Liwu Lin Zhusheng Xu Tao Zhang Jianzhong Niu Dongbai Liang 《Reaction Kinetics and Catalysis Letters》1998,63(2):391-396
Pt LIII-edge XANES and EXAFS were employed to investigate the nature of Pt/γ-Al2O3, Pt−Sn/γ-Al2O3 and Pt−Fe/γ-Al2O3 catalysts. The results indicated that Pt species on these catalysts were all in the oxidized states before reduction, and
in the metallic states after reduction. The dispersity of the Pt species on the catalysts was very high after reduction. The
electronic properties of the highly dispersed Pt species were different from that of the bulk Pt in large crystallites. An
interaction between Pt and the metal-oxide modified γ-Al2O3 support is proposed. The interaction improved the dispersity of the Pt species on the catalysts and is thought to be the
reason for the enhanced activity and selectivity for dehydrogenation reactions over these catalysts. 相似文献
13.
Xiujie Li Weiping Zhang Shenglin Liu Sujuan Xie Xiangxue Zhu Xinhe Bao Longya Xu 《Journal of molecular catalysis. A, Chemical》2009,313(1-2):38-43
Promoting effects of Mg in heterogeneous Mo/HBeta–Al2O3 catalyst have been carefully studied for cross-metathesis of ethene and butene-2 to propene. The catalyst shows good stability with Mg content in the range of 1–2 wt%. Such effect may be attributed to the elimination of weak acid sites through introduction of Mg which suppresses the side olefin oligomerization reaction, as evidenced from NH3-TPD and 1H MAS NMR results. Addition of more Mg content to 3 wt% may change the state and reducibility of Mo species, as indicated from the UV–vis, UV-Raman and H2-TPR measurements. The increasing difficulty for the reduction of Mo(VI) species is closely related with the poor performance of 3 wt% Mg–4Mo/HBeta–30% Al2O3 catalyst in the metathesis reaction. 相似文献
14.
Pt−Sn bimetallic catalysts were prepared by a CVD technique in which Sn was added by passing volatile organometallic compounds
over Pt/ZnAl2O4 in a H2 flow. Mixed Pt−Sn sites improve the activity of isobutane dehydrogenation, while Sn on the support improves the selectivity. 相似文献
15.
Lucie Smoláková árka Botková Libor apek Peter Priecel Agnieszka Soltysek Martin Kout Lenka Matějová 《催化学报》2013,34(10):1905-1913
Ni/Al2O3 catalysts for oxidative dehydrogenation(ODH) of ethane were prepared by impregnation of Al2O3 with nickel acetate or nickel nitrate,and by mechanical mixing of NiO and Al2O3.The Ni-based catalysts were characterized by N2 adsorption-desorption,X-ray diffraction,diffuse reflectance UV-visible diffuse reflectance spectroscopy,and temperature-programmed reduction of hydrogen.The results showed that formation of crystalline NiO particles with a size of < 8 nm and/or non-stoichiometric NiO species in the Ni/Al2O3 catalysts led to more active species in ODH of ethane under the investigated reaction conditions.In contrast,tetrahedral Ni species present in the catalysts led to higher selectivity for ethene.Formation of large crystalline NiO particles(22-32 nm) over Ni/Al2O3 catalysts decreased the selectivity for ethene. 相似文献
16.
Phenylacetylene hydrogenation on Pd, Pt and Pd–Pt/Al2O3 catalysts has been studied. In all catalysts activity was found not to depend on particle size. However, selectivity to styrene was found to depend on Pd/Al2O3 catalysts. Carbon deposition in both metal and support explains such a behavior. Nevertheless, in small Pd particles a longer residence time of styrene may control the selectivity. 相似文献
17.
A. Brito R. Arvelo R. Villarroel M. T. García 《Reaction Kinetics and Catalysis Letters》1995,55(1):85-91
A model has been used to predict the temperature, butene and carbon concentration profiles in a fixed bed reactor during butene-1 dehydrogenation when Cr2O3/Al2O3 is used as a catalyst. Furthermore, the model gives information about the temperature, butene and carbon concentration profiles inside the pellet. 相似文献
18.
A. Drelinkiewicz P. Byszewski A. Bielanski 《Reaction Kinetics and Catalysis Letters》1996,59(1):19-27
Catalytic hydrogenation of C60 with H2 or by hydrogen transfer reactions using Pd/SiO2, Rh/Al2O3 and Ru/Al2O3 has been studied. The final products containing partially hydrogenated C60 fullerence C60H42–C60H46 were characterized by FTIR, UV and NMR methods. 相似文献
19.
F. M. Bautista J. M. Campelo A. Garcia D. Luna J. M. Marinas A. A. Romero 《Reaction Kinetics and Catalysis Letters》1996,57(1):61-70
The alkylation of toluene with methanol over AlPO4-Al2O3 (5–15 wt.% Al2O3) catalysts produces a mixture of xylenes (XYL) although trimethylbenzenes (TMB) were also found. The TMB selectivity increased with temperature at the expense of XYL selectivity. Isomer distribution was approximately 48, 24 and 27 mol% foro-, m- andp-XYL, and 74, 26 and 0 mol% for 1,2,3-, 1,2,4- and 1,3,5-TMB, both quite different from the equilibrium isomer composition. The catalytic activity increased with alumina content, however, it decreased on increasing the calcination temperature in the 923–1273 K range. Good correlations between catalytic activity and the increase in acidic properties with Al2O3 loading (as determined by base chemisorption, in the gas phase,versus pyridine and 2,6-dimethylpyridine) have been obtained. 相似文献
20.
The system CpTiCl3/Al2O3–SiO2 (0–100 wt.% of Al2O3), (Cp=cyclopentadienyl) was reduced with a tenfold excess of NaNp (Np=naphthalene) in THF and argon atmosphere at room temperature. Only titanium(IV) and titanium(III) compounds were found by the polarographic method in the systems studied. The amount of the titanium(III) compounds is influenced by the acidity of supports. 相似文献