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41.
Fengyu Zhao Shin-ichio Fujita Jianmin Sun Yutaka Ikushima Masahiko Arai 《Catalysis Today》2004,98(4):1695-528
Hydrogenation of a series of substituted nitro compounds such as 2-,3-,4-nitroanisole, 2-,3-,4-nitrotoluene, 2,4-dinitrobenzene and 2,4-dinitrotoluene has been studied in supercritical carbon dioxide, scCO2 (two phases), and ethanol (three phases) with a 5 wt.% carbon supported platinum catalyst. The solubility of these compounds in scCO2 has also been examined in the presence and absence of hydrogen. The solubility of those nitro compounds increases with increasing CO2 pressure but decreases with the presence of hydrogen. The solubility is in the order of nitrotoluene > nitroanisole > dinitrotoluene, dinitrobenzene. Although the total conversion obtained with hydrogenation in scCO2 is similar to that in ethanol, the selectivity to amino products is higher in the former reaction medium, indicating that scCO2 is an ideal medium for the production of amino compounds with hydrogenation of nitro substrates using conventional supported metal catalysts. 相似文献
42.
The development of a high throughput reactor for the catalytic screening of three phase reactions 总被引:1,自引:0,他引:1
Stuart Thomson Christian Hoffmann Silvia Ruthe H. -W. Schmidt Ferdi Schüth 《Applied Catalysis A: General》2001,220(1-2):253-264
The design and utilisation of a reactor for the optimisation of multiple heterogeneous catalytic reactions in liquid phase is described. With the ability to screen up to 25 samples simultaneously at a maximum pressure of 50 bar, the reactor is one of the first to be designed specifically for what is termed stage II, the optimisation phase, of catalytic high throughput experimentation (HTE). Experiments demonstrating the reliability and reproducibility of the reactor are described, including the use of the reactor to study the catalytic hydrogenation of crotonaldehyde (CrAld) over bimetallic samples based on a commercial 5 wt.% Pt on activated carbon catalyst. Modification of the mono-metallic Pt sample by the impregnation of aqueous metal salts and various pre-treatments, resulted in 140 bimetallic catalysts that were used in the hydrogenation study. The changes observed in both selectivity and reactivity of the modified catalysts are described and show, by way of example, how the speed of catalyst screening can be increased by at least an order of magnitude. 相似文献
43.
M. Di Serio V. Balato A. Dimiccoli L. Maffucci P. Iengo E. Santacesaria 《Catalysis Today》2001,66(2-4):403-410
The hydrogenation of 1,5-cyclo-octadiene has been studied on well-defined Pd catalysts. The reaction is affected by internal diffusion of hydrogen into the catalyst particles. Despite this limitation, the reaction orders of the reactants have been determined. All the performed kinetic runs have been simulated and the kinetic and mass-transfer parameters giving the best fit of experimental data have been evaluated. The reaction occurs in two steps, in the first, a conjugate diene (1,3-cyclo-octene) is formed via isomerization, then, hydrogenation occurs quickly forming the monoene. The hydrogenation of the obtained cyclo-octene is relatively slow and strongly inhibited by the presence of the cyclo-octadiene. This last reaction has, therefore, been used for comparing the activities of different palladium catalysts showing an exponential behaviour of the reaction rate with the metal dispersion. 相似文献
44.
S. R. de Miguel M. C. Romn-Martínez D. Cazorla-Amors E. L. Jablonski O. A. Scelza 《Catalysis Today》2001,66(2-4):289-295
In this paper, a study on the hydrogenation of carvone by using Pt/Al2O3, PtSn/Al2O3, PtGe/Al2O3, Pt/C and PtSn/C is reported. TPR, H2 chemisorption, XPS and test reaction results show that the addition of a second metal to Pt leads to important modifications of the structure of the metallic phase, though these modifications are different according to the nature of the support (Al2O3 or C). The activity and selectivity of these catalysts in carvone hydrogenation depend not only on the composition of the metallic phase, but also on the nature of the support. Thus, adding Sn or Ge to Pt/Al2O3 enhances the selectivity to unsaturated ketones (at a fixed carvone conversion, Xcarv=1). When Pt is supported on activated carbon, small amounts of unsaturated alcohols are observed. The Sn addition to Pt/C sharply enhances the selectivity to carveol formation (the doubly unsaturated alcohol) reaching values close to 100% at the initial stages of the reaction. 相似文献
45.
Myoung-Jae Choi Jun-Sik Kim Hak-Ki Kim Sang-Bong Lee Yong Kang Kyu-Wan Lee 《Korean Journal of Chemical Engineering》2001,18(5):646-651
Catalytic hydrogenation of CO2to produce hydrocarbons was conducted in a fixed bed reactor (1.6 cm-IDx60 cm-High). Fe-K based catalysts (KRICAT-A, B) were
used for more than 850 hours to maintain CO2 conversion level up to 30 C-mol% in the fixed bed micro-reactor. Effects of operating variables on the CO2 conversion, hydrocarbon yield and its selectivity were investigated. The CO2 conversion and total hydrocarbon yield increased with increasing reaction temperature (250-325 °C), pressure (0.5-2.5 MPa)
and H2/CO2 mol ratio (2-5); however, they decreased with increasing space velocity (1,000-4,000 ml/gcathr) in the reactor. The selectivities of liquid products increased with increasing reaction pressure; however, they decreased
with increasing temperature, space velocity and H2/CO2 ratio. From the results of an experimental study, optimum operating conditions for the maximum yield of olefinic liquid products
were found as T=315 °C, P=1.5 MPa, SV=2,000 ml/gcathr and H2/CO2 ratio=3 in the fixed bed reactor within these experimental conditions.
Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8-10, 2001), dedicated to Prof. H. S. Chun on the occasion of his
retirement from Korea University. 相似文献
46.
Jun Sik Kim Hak Ki Kim Sang Bong Lee Myoung Jae Choi Kyu Wan Lee Yong Kang 《Korean Journal of Chemical Engineering》2001,18(4):463-467
Characteristics of CO2 hydrogenation were investigated in a fluidized bed reactor (0.052 m IDxl.5 m in height). Coprecipitated Fe-Cu-K-Al catalyst
(dρ=75–90 Μm) was used as a fluidized solid phase. It was found that the CO2 conversion decreases but the CO selectivity increases, whereas the space-time-yield attains maximum values with increasing
gas velocity. The CO2 conversion has increased, but CO selectivity has decreased with increasing hydrogenation temperature, pressure or H2/CO2 ratio in the fluidized bed reactor. Also, the CO, conversion and olefin selectivity appeared to be higher in the fluidized
bed reactor than those of the fixed bed reactor.
Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his
retirement from Korea University 相似文献
47.
This article reviews the enantio-differentiating hydrogenation of prochiral ketones over a asymmetrically modified catalyst, focusing on the hydrogenation of simple prochiral alkanones. The parameters affecting catalytic activity and enantiodifferentiating ability are considerable in number, and each parameter should be optimized in order to attain a highperformance enantio-differentiating catalyst. Optimization of the parameters and the mode of enantio-differentiation are discussed and compared with the enantio-differentiating hydrogenation of β-ketoesters. 相似文献
48.
Inferior crude oil and fuel oil upgrading lead to escalating increase of hydrogen consumption in refineries. It is imperative to reduce the hydrogen consumption for energy-saving operations of refineries. An integration strategy of hydrogen network and an operational optimization model of hydrotreating (HDT) units are proposed based on the characteristics of reaction kinetics of HDT units. By solving the proposed model, the operating conditions of HDT units are optimized, and the parameters of hydrogen sinks are determined by coupling hydrodesulfurization (HDS), hydrodenitrification (HDN) and aromatic hydrogenation (HDA) kinetics. An example case of a refinery with annual processing capacity of eight million tons is adopted to demonstrate the feasibility of the proposed optimization strategies and the model. Results show that HDS, HDN and HDA reactions are the major source of hydrogen consumption in the refinery. The total hydrogen consumption can be reduced by 18.9% by applying conventional hydrogen network optimization model. When the hydrogen network is optimized after the operational optimization of HDT units is performed, the hydrogen consumption is reduced by 28.2%. When the benefit of the fuel gas recovery is further considered, the total annual cost of hydrogen network can be reduced by 3.21×107 CNY·a-1, decreased by 11.9%. Therefore, the operational optimization of the HDT units in refineries should be imposed to determine the parameters of hydrogen sinks base on the characteristics of reaction kinetics of the hydrogenation processes before the optimization of the hydrogen network is performed through the source-sink matching methods. 相似文献
49.
50.
Hydrogenation of liquid organic hydrogen carriers is usually carried out in liquid phase. To measure the kinetics of this hydrogenation, an experimental setup using in situ Raman spectroscopy for analysis of the reaction mixture is proposed. With this setup it is possible to perform hydrogenation reactions at temperatures of up to 573 K and pressures up to 25 MPa. For validation of the experimental setup the hydrogenation of 1‐octene was measured in liquid phase. The reaction progress can be monitored in detail by Raman spectroscopy. To determine kinetic parameters from the experimental data, two modeling approaches were applied: a classic kinetic model and a thermodynamic kinetic model. The results were compared to literature data. 相似文献