用乙二醇法和浸渍法制备两种负载在堇青石上的钴基负载催化剂,并用XRD、XPS、TPR和TPD对制备的催化剂进行表征,比较两种催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,与浸渍法制备的Co/cord催化剂相比,乙二醇法制备的催化剂Co/cord-EG对甲苯催化燃烧活性明显提高。应用乙二醇法制备Co/cord-EG负载型催化剂,Co元素主要以Co2+存在于载体表面;而传统浸渍法制备的Co/cord催化剂,Co元素是以Co2+与Co3+的两种化学状态存在于载体表面。应用乙二醇法制备Co/cord-EG负载型催化剂,有助于在载体表面形成比较均匀的吸附活性位。应用乙二醇法制备的Co/cord-EG催化剂,催化活性组分能在载体表面上以更小颗粒而且更高的分散度存在,从而能明显提高其催化活性。
In the present work we studied the toluene decomposition activity of cobalt based catalysts prepared by chemical reduction with ethylene glycol(EG),in comparison to catalysts prepared via typical impregnation procedure.The properties of the supported Co catalysts were studied by means of X-ray diffraction(XRD),temperature programmed reduction by H2(H2-TPR),X-ray photoelectron spectroscopy(XPS),temperature program desorption(TPD).Activity tests of the catalysts were carried out in a fixed bed reactor.Results showed that the catalytic activity of the catalyst Co/cord-EG prepared by chemical reduction with ethylene glycol was much higher than that of the catalyst Co/cord prepared by the conventional impregnation.The cobalt species presented on the catalyst Co/cord-EG were mainly in the form of cobalt(Ⅱ) oxide,and those presented on the catalyst Co/cord were in the forms of both cobalt(Ⅱ) oxide and cobalt(Ⅲ) oxide.The application of the EG reduction method favored the formation of smaller particles and higher dispersion of cobalt species on the supports.As a consequence of that,the catalytic activity of the catalyst Co/cord-EG was greatly improved in comparison with the catalyst Co/cord pretreated by the traditional impregnation.