甲醇与异丁烯在改性β分子筛上的吸附行为研究

采用过渡应答技术对甲醇和异丁烯在改性β分子筛上的吸附行为进行了研究，研究结果表明，异丁烯和甲醇在改性β分子筛上符合先快吸附后慢吸附的Elovich吸附规律。甲醇的吸附量大，但速率慢；异丁烯吸附量小，速率快。由于甲醇的饱和吸附量大于异丁烯的饱和吸附量，对合成MTBE反应的选择性具有重要意义，对它们的吸附行为进行动力学研究，得到了不同温度下吸附活化能随吸附量变化的关系。不同温度下相对饱和吸附量预测表明：当温度从288K升高到383K时，qMeOH/q1BWW 6．1降低到4．6，甲醇的相对饱和吸附量随温度升高而减小，但仍保持较高值，证明了甲醇在分子筛上是强吸附的观点，为解释选择性高和动力学方程的建立提供依据，对反应机理的研究有指导作用。

STUDY ON THE ADSORBING BEHAVIORS OF METHANOL AN ISOBUTYLENE ON MODIFIED -b ZEOLITE

The behaviors of methanol and isobutylene adsorbed over a modified-b zeolite catalyst were studied by the transient response method in a chromatogram-reactor. The experimental results showed that: the adsorption of methanol and isobutylene conform to Elovich equation. The adsorption quantity of methanol was bigger than that of isobutylene, but the adsorption rate was slower. The adsorption kinetics of MeOH and IB were studied also. The activation energy of adsorption were obtained: EαMeOH=4156+aq and EαIB=10247+aq respectively. The prediction of relative adsorption quantity showed that the qMeOH/qIB changed from 6.1 to 4.6 when temperature inceased from 288K to 383K. The result proved the adsorption of methanol is strong. It can be explained that the higher selectivity to MTBE synthesized from MeOH and IB over zeolite catalysts is due to the higher relative adsorption quantity of methanol on the surface of zeolitse. These results were important for determining the mechanism of MTBE synthesis from MeOH and IB as well as developing the reaction kinetics.