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用脉冲微反色谱技术研究了在镍基粘结型催化剂上CH_4解离和CO歧化反应动力学,以及稀土氧化物的催化作用.因碳在表面沉积对活性有影响,引入了积碳因子,得到了满意结果.稀土氧化物的合适加入量均可降低反应活化能.对CH_4解离反应,La_2O_3和CeO_2的适宜值均为3%(mass),而CO歧化反应La_2O_3为4.5%(mass),CeO_2为3%(mass).在稀土氧化物加入量为0-6%(mass)内,活化能降低范围:CO歧化为33kJ/mol,CH_4解离为44kJ/mol.认为吸附态的甲烷脱除第一氢原子是反应控制步骤,稀土氧化物通过对吸附态的甲烷分子和邻近Ni原子的正电吸引,改变了甲烷解离的机理,使活化能降低.CO借助稀土氧化物中晶格氧转移使其更易实现歧化反应,使活化能降低.发现CO歧化反应中生成的碳对活性影响比较小,认为这是由于沉积在镍表面上的碳迁移到载体上的缘故.
The kinetics of CH 4 dissociation and CO disproportionation and the catalysis of rare earth oxides on nickel-base bonded catalysts were studied by pulsed microreactor technique. Because of the influence of carbon deposition on the surface activity, carbon deposition factors were introduced, The results showed that the proper activation energy could be obtained by reducing the activation energy of the rare earth oxides, and the suitable values of La_2O_3 and CeO_2 were 3% (mass) for CH_4 dissociation reaction and 4.5% (mass%) for CO disproportionation reaction, respectively , CeO 2 is 3 mass% .In the range of 0-6 mass% rare earth oxides, the range of activation energy reduction is: CO disproportionation is 33 kJ / mol and CH 4 dissociation is 44 kJ / mol. The adsorbed methane Removal of the first hydrogen atom is the reaction control step, the rare earth oxide through the adsorption of methane molecules and the adjacent Ni atoms of the positive charge, changing the mechanism of methane dissociation, so that the activation energy is reduced .CO with rare earth oxide in the crystal Oxygen transfer makes it more susceptible to disproportionation reaction and decreases the activation energy. It was found that the carbon produced in the CO disproportionation reaction had little effect on the activity, which is attributed to the migration of carbon deposited on the surface of nickel to the support.