Papers by Keyword: Catalytic Hydrogenation

Abstract: The catalytic hydrogenation kinetics of N-ethylcarbazole over 5 wt% Ru/Al₂O₃ was investigated at various temperatures. The results shows that the hydrogenation reaction was exothermic and high temperature is unfavorable for the reaction rate. Fully hydrogenation was achieved within 1 hour under the best reaction temperature of 170 °C. The kinetics of N-ethylcarbazole follows the first-order kinetics in terms of the reactant concentration but independent of hydrogen pressure, which was maintained as a constant in the reaction process. The apparent activation energy of N-ethylcarbazole hydrogenation reaction at 150-180 °C was found to be 71.2 kJ/mol.

Abstract: An improved method for practical synthesis of 4-azaindole from 2-chloro-3-nitropyridine has been developed. In the key step, decarboxylation with acetic acid afforded 3-nitro-2-pyridylacetonitrile in high yield.

Abstract: By using heavy polycyclic aromatic hydrocarbon from a factory in Northwest China as raw material and 6% Ni/USY as catalyst, a study on hydrogenation process is carried out with a high-pressure hydrocracking assessment device, which mainly focuses on investigating the effect of LHSV, oil hydrogen ratio, temperature and pressure on heavy polycyclic aromatic hydrocarbon. Experimental results show that under the condition that the optimum LHSV is 3.0 h^-1 and the ratio of oil to hydrogen is 600, both conversion rate of heavy components and yield of one-membered ring increase at first and then decrease with reaction temperature, with the peak value of conversion rate at 320°C and yield peak at 340°C. Though fluctuates with the increase of pressure, but conversion rate of heavy components shows an overall upward trend. Yield of one-membered ring increases at first and then decreases with pressure, and eventually tends to stabilize. When the temperature is greater than 300°C, the yield slightly fluctuates with pressure and shows an overall increasing trend.

Abstract: We have successfully prepared a novel passivation Ni/HY catalyst by the technologies of macerate-precipitatio.The catalysts are comprised of two contents: HY as carrier, Ni as active component，and we put it into the process of preparating aromatic amines.The nature of the catalysts was discussed based on the characterization results of BET , IR , SEM , XRD , TEM ,TPD , XPS and TPR . The catalytic hydrogenation technology for 2,4-dinitrobenzene in liquid phase can be an attractive and elegant routine for production of 2,4-tolylenediamine. The catalytic activity is evaluated at 2.2 MPa, 90 °C, 750r/min, solvent with reaction materials mass ratio of 60, catalyst with reaction materials mass ratio of 0.1. In the catalytic test, The experimental results over the catalyst showed that 2,4-dinitrobenzene and 2,4-tolylenediamine conversion and selective of 99.88% and 99.16% were obtained respectively.It is found that the catalyst is highly dispersion, stable, and reusable. No obvious deactivation of the catalyst was observed after repeated using twelve times.

Abstract: Pd-only catalyst supported on activated carbon has been prepared by chemical impregnation and used to catalyze the hydrogenation of 2-chloro-6-nitrotoluene (2-CNT) to 3-chloro-2-methylaniline in solvent-free condition. The effects of reaction temperature，H2 pressure on the hydrogenation have been investigated. The reaction showed very high selectivity with the dehalogenation side product with a yield of less than 1.2 %. The most favorable conditions could be temperature= 353 K, stirring speed= 1200 rpm, H2 pressure= 1 MPa. The catalytic hydrogenation reaction was found to have a zero order with hydrogen and 1 order with 2-CNT. The apparent activation energy of the hydrogenation was 60.58 kJ/mol.

Abstract: The Al2O3-Supported Ni Catalyst was prepared by chemical reduction method, and take benzaldehyde as catalytic hydrogenation model to explore the effect in catalytic hydrogenation of benzaldehyde at different time and temperatures. The results show that the best temperature is between 60°Cand 80°C, and the catalytic time is about 1-2 h. Furthermore, the catalytic effect of Ni-Co/Al2O3 is best, it should be due to Co and Ni forming to alloys and obtain the function of the dual catalyst, which is conducive to benzaldehyde was activated and forming benzyl alcohol.

Abstract: Effect of ultrasonic waves, premonitory LixMoS2 and La/Ni-MoS2 composites were prepared by n-butyl lithium intercalating in the MoS2 layers, using the single-molecular-layer exfoliated-restacked technology. The effect of catalyst on the performance was investigated with catalytic hydrogenation of sulfolene over composites as probe reaction. The catalyst evaluation results show that the optimum atomic ratio, hydrogen pressure and reactive temperature were n(La):n(Ni) = 0.05, 2.5 MPa and 60 °C, respectively. Under such condition, conversion of sulfolene was 99.8%, the yield of sulfolane reached 95.5%.

Abstract: One new Ruthenium and one known Iron bimetallic carbonyl clusters containing triphos (1,1,1-tris(diphenylphosphinomethyl)ethane) ligand have been prepared as catalyst to study the reduction of amide to amine. All clusters were characterized by elemental analysis, 1HNMR, 31PNMR and IR spectroscopy. The reduction of N,N-dimethylbenzamide and N,N-diethyl-(3-methyl) benzamide catalyzed by Ru and Fe carbonyl clusters were investigated at 100 ~ 110 °C for 24 ~ 28h, polymethylhydrogensiloxane (PMHS) as reduction agent. The products were analysized using GC-MS, IR and UV-vis spectroscopy and an excellent yield (97%) of N,N-diethyl- (3-methyl)benzamine was obtained when using 3 mol% of bimetallic ruthenium carbonyl cluster as catalyst. The data of IR and UV-vis show that the frameworks of clusters are not changed remarkably during the reaction.

Abstract: A 2 wt % Pd/C catalyst has been prepared by chemical impregnation and used to catalyze the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) in solvent-free conditions. The effects of reaction temperature, H₂ pressure, and stirring intensity on the hydrogenation kinetics have been investigated. The hydrogenation reaction showed very high selectivity with dehalogenation side products as low as 0.3% of total yield. The favorable reaction conditions were found to be temperature T = 383 K, stirring speed = 900 rpm, and feeding ratio CNB/catalyst = 200/1 (m/m). The recycled Pd/C still retained more than 98% of its original selectivity after 12 repeat used, indicating the catalyst had strong potentials for commercial application at industrial scale.

Abstract: Palladium-copper bimetallic catalysts supported over different supporters were prepared by chemical reduction method, and their catalytic performance was investigated with the hydrogenation of nitrate ions in drinking water under mild conditions. The results show that Pd-Cu/ZSM-5 bimetallic catalyst has the highest catalytic activity among all used catalysts. In addition, nitrate conversion influenced by metal content, metal molar ratio (Pd:Cu) and the addition of CO₂ are also discussed. It is well established that the addition of CO₂ has changed the reduction path of the intermediate nitrite, but is no influence on the steps of nitrate-to-nitrite reduction. In the end, the mechanism of catalytic nitrate reduction was discussed on the basis the literature results.