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1.
J. Margitfalvi S. Gbölös E. Kwaysser M. Hegedüs F. Nagy L. Koltai 《Reaction Kinetics and Catalysis Letters》1984,24(3-4):315-321
The influence of rhenium on the behavior of a Pt/Al2O3 catalyst was studied in n-hexane reaction by means of dilution of the catalyst bed with Re/Al2O3. Parallel to activity, selectivity and ageing data obtained in slug pulse and continuous flow reactors, the amount of the surface carbon formed during the reaction was determined and its reactivity in hydrogen atmosphere was also studied. It is suggested that in the presence of rhenium due to the increase in the amount of hydrogen available for hydrogen consuming reactions including hydrodepolymerization of the carbonaceous surface overlayer, the routes of ageing processes are changed, resulting in lower carbon content on the catalyst and less pronounced catalyst deactivation.
Pt/Al2O3 -, Re/Al2O3. , , , , . , , , , , , , .相似文献
2.
Yu. A. Ryndin S. Gbölös V. I. Zaikovskii J. Margitfalvi Yu. I. Yermakov 《Reaction Kinetics and Catalysis Letters》1982,21(1-2):91-95
The addition of gallium is shown to increase Pt dispersity and its stability to deactivation in n-hexane dehydrocyclization, to decrease the rate of n-hexane hydrogenolysis and to increase the selectivity to benzene, apparently, due to the interaction of Pt clusters with surface Ga ions.
, -, - . .相似文献
3.
The reactivity of the carbonaceous surface overlayer formed on Pt/Al2O3 catalysts in n-hexane dehydrocyclization has been studied by high temperature Pyrolysis Gas Chromatography. This method can be used to characterize surface carbon overlayers formed on different catalysts in the course of hydrocarbon reactions.
, Pt/Al2O3 -, . , .相似文献
4.
Szijjárto GP Tompos A Héberger K Margitfalvi JL 《Combinatorial chemistry & high throughput screening》2012,15(2):105-113
Effects of different catalyst components on the catalytic performance in steam reforming of ethanol have been investigated by means of Artificial Neural Networks (ANNs) and Partial Least Square regression (PLSR). The data base consisted of ca. 400 items (catalysts with varied composition), which were obtained from a former catalyst optimization procedure. Marten's uncertainty (jackknife) test showed that simultaneous addition of Ni and Co has crucial effect on the hydrogen production. The catalyst containing both Ni and Co provided remarkable hydrogen production at 450°C. The addition of Ceas modifier to the bimetallic NiCo catalyst has high importance at lower temperatures: the hydrogen concentration is doubled at 350°C. Addition of Pt had only little effect on the product distribution. The outliers in the data set have been investigated by means of Hotelling T2 control chart. Compositions containing high amount of Cu or Ce have been identified as outliers, which points to the nonlinear effect of Cu and Ce on the catalytic performance. ANNs were used for analysis of the non-linear effects: an optimum was found with increasing amount of Cu and Ce in the catalyst composition. Hydrogen production can be improved by Ce only in the absence of Zn. Additionally, negative cross-effect was evidenced between Ni and Cu. The above relationships have been visualized in Holographic Maps, too. Although predictive ability of PLSR is somewhat worse than that of ANN, PLSR provided indirect evidence that ANNs were trained adequately. 相似文献
5.
Ervin Gy. Szabó Mihály Hegeds József L. Margitfalvi 《Reaction Kinetics and Catalysis Letters》2008,93(1):119-125
Au/Al2O3 catalysts were modified by different redox metal oxides, such as FeOx, MnOx and CoOx, resulting in a pronounced activity increase in CO oxidation. 相似文献
6.
Tompos A Margitfalvi JL Hegedus M Szegedi A Fierro JL Rojas S 《Combinatorial chemistry & high throughput screening》2007,10(1):71-82
In the present work, the role and the effect of platinum and gold on the catalytic performance of ceria supported tri-metallic Pt-Pd-Au catalysts have been studied. The optimum composition of these tri-metallic supported catalysts has been discovered using methods and tools of combinatorial catalyst library design. Detailed catalytic, spectroscopic and physico-chemical characterization of catalysts in the vicinity of the optimum in the given compositional space has been performed. The temperature-programmed oxidation of methane revealed that the addition of Pt and Au to Pd/CeO2 catalyst resulted in higher conversion values in the whole investigated temperature range compared to the monometallic Pd catalyst. The time-on-stream experiments provided further evidence for the high-stability of tri-metallic catalysts compared to the monometallic one. Kinetic studies revealed the stronger adsorption of methane on Pt-Pd/CeO2 catalysts than over Pd/CeO2. XPS analysis showed that Pt and Au stabilize Pd in a more reduced form even under condition of methane oxidation. FTIR spectroscopy of adsorbed CO and hydrogen TPD measurements provided indirect evidences for alloying of Pt and Au with Pd. CO chemisorption data indicated that tri-metallic catalysts have increased accessible metallic surface area. It is suggested that advantageous catalytic properties of tri-metallic Pt-Au-Pd/CeO2 catalysts compared to the monometallic one can be attributed to (i) suppression of the formation of ionic forms of Pd(II), (ii) reaching an optimum ratio between Pd0 and PdO species, and (iii) stabilization of Pd in high dispersion. The results also indicate that Pd0 - PdO ensemble sites are required for methane activation. 相似文献
7.
Ferenc Somodi Mihály Heged?s István E. Sajó Sergio Rojas József L. Margitfalvi 《Applied Surface Science》2009,256(3):726-736
In this study the influence of SnOx nanoparticles on the catalytic performance of alumina-supported gold catalysts was investigated in CO oxidation. The tin modified supports were prepared by grafting of tetraethyltin onto the surface of alumina via its hydroxyl groups. The decomposition of organometallic surface species in oxygen yielded highly dispersed tin oxide on the surface of alumina. Gold was introduced onto the tin modified alumina support by both deposition-precipitation with urea and direct anionic exchange techniques using HAuCl4 solution. Based on catalytic and different spectroscopic measurements it is suggested that the presence of “Snn+-Au ensemble sites” is responsible for the increased activity of these catalysts. 相似文献
8.
J. Margitfalvi M. Hegeds S. Szabó F. Nagy 《Reaction Kinetics and Catalysis Letters》1982,18(1-2):89-93
A -Al2O3 supported Pd–Pt bimetallic catalyst prepared by electrochemical metal adsorption has been tested in n-hexane dehydrocyclization. The Pd–Pt/Al2O3 catalyst, after calcination in oxygen followed by hydrogen treatment, showed higher activities and better selectivities for benzene and iso-hexane formation. The Pd–Pt/Al2O3 catalyst appeared to be less sensitive to the changes in the temperature of hydrogen treatment than the base Pt/Al2O3 catalyst.
Re–Pt, -Al2O3, . -. , Re–Pt/Al2O3, , , , . , Pt/Al2O3.相似文献
9.
Hydrogenation of C2H2:C2H4 mixtures using a double labelling method has been studied. Both in the presence and absence of ethylene the rate of acetylene hydrogenation on its partial pressure proceeds through a maximum and the rate is higher when ethylene is added. Using14C–C2H2 it was demonstrated that at low acetylene partial pressures the main route of acetylene hydrogenation was the formation of ethane and C4 hydrocarbons. Using14C–C2H4 it was also shown that at certain acetylene partial pressures the formation of ethane from ethylene completely ceased. Different surface species are suggested and a reaction mechanism is proposed.
C2H2:C2H4, . , , . C14–C2H2, , C4. C14–C2H4, , . .相似文献
10.
J. Margitfalvi S. Gbölös M. Hegedüs F. Nagy 《Reaction Kinetics and Catalysis Letters》1982,21(4):541-547
Pt/Al2O3 catalysts with good reforming activity were prepared from [(CH3)3PtX]4 (X=Cl, Br, I) complexes and tested in pulse and continuous-flow reactors in n-hexane dehydrocyclization. It has been demonstrated that [(CH3)3PtX]4 complexes are excellent precursors of supported platinum catalysts.
Pt/Al2O3 [(CH3)3 PtX]4 (X=Cl, Br, I) -. , [(CH3)3PtX]4 .相似文献