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以流动床微分反应器研究了Bi_2MO_3O_(12)-Bi_2O_3催化剂上的丙烯氧化动力学。丙烯和氧的分压范围分别为0.05—0.95atm和0.07—0.80atm。当氧和丙烯分压低于0.30atm时,丙烯醛的生成速度对丙烯为一级对氧为0.5级。表观活化能为30.1kcal mol~Ⅰ。当丙烯和氧分压高于0.30atm时,丙烯醛生成反应的动力学不能用幂速度方程描述。丙烯醛的生成速度对丙烯和氧分压存在着极大值。热脱附实验表明,在低于150℃时,分子态丙烯可以吸附于氧化态催化剂。但当温度高于300℃时,丙烯则不以分子态吸附,且脱附物为丙烯醛、一氧化碳和二氧化碳。在广阔的温度区(25—500℃)氧皆不以分子态处于催化剂上。因此,建议了以表面双位反应为速控步骤的氧化还原机理。
The kinetics of propylene oxidation over Bi_2MO_3O_ (12) -Bi_2O_3 catalysts was investigated using a fluidized bed differential reactor. The partial pressures of propylene and oxygen range from 0.05 to 0.95 atm and 0.07 to 0.80 atm, respectively. When the oxygen and propylene partial pressure is less than 0.30atm, the rate of generation of acrolein is 0.5 for propylene and 0.5 for oxygen. The apparent activation energy is 30.1 kcal mol ~ Ⅰ. The kinetics of the acrolein formation reaction can not be described by the power velocity equation when the partial pressures of propylene and oxygen are above 0.30 atm. The rate of acrolein formation has a maximum value for the partial pressure of propylene and oxygen. Thermal desorption experiments show that below 150 ℃, the molecular structure of propylene can be adsorbed on the oxidation state catalyst. However, when the temperature is higher than 300 ° C, propylene is not adsorbed by the molecular state, and the desorbed substances are acrolein, carbon monoxide and carbon dioxide. In a wide temperature range (25-500 ℃) oxygen is not in the molecular state on the catalyst. Therefore, it is suggested that the surface double reaction is the redox mechanism of the quick control step.