硅藻土负载H6PMo9V2Nb1O40催化剂上乙烷氧化制乙酸和乙醛的反应性能

The heteropoly acid complex H6PMo9V2Nb1O40 was prepared by the method of common acidification. Kieselguhr supported heteropoly compounds PMo9V2Nb1/K was prepared by the isovolumic impregnation. Its reducibility and acidity and the chemisorption and reactivity for C2H6 oxidation were characterized by IR, H２-TPR, NH３-TPD and microreactor techniques. The results showed that the catalyst PMo9V2Nb1/K still keeps the original Keggin structure like H6PMo9V2Nb1O40, but the activity of the crystal oxygen increased obviously and the strength and amount of the Br ö nsted acidity decreased in some degree. The hydrogen in C2H6 can be adsorbed on the surface oxygen sites in Nb—O—Mo or V—O—Mo bonds of the catalyst to form a molecular adsorption state. With the temperature rising, the C—H bond in the adsorbed C2H6 on the bridge oxygen of Nb—O—Mo bond would be broken to form dissociative adsorption states, then react with the surface oxygen to form the target products. Under the optimal conditions of 240 ℃, 0.4 MPa and space velocity 2 000 h-1, the conversion of ethane reached 22.5%, with the selectivity of 90.8% to acetic acid and acetaldehyde. The support of heteropoly compounds PMo9V2Nb1 on kieselguhr improved remarkably the conversion of ethane.