III International Conference

PP-II-82OPTIMIZATION OF SYNTHESIS PROCEDURE OF AEROGEL VOx/MgOCATALYST FOR OXIDATIVE DEHYDROGENATION OF LIGHTHYDROCARBONSMishakov I.V., Masel’skaya E.V., Vedyagin A.A., Nizovskii A.I., Starokon E.V.Boreskov Institute of Catalysis SB RAS, Novosibirsk, RussiaE-mail: mishakov@catalysis.ruThe modified aerogel technology for the synthesis of VO x /MgO catalyst has beendeveloped. Surface area of aerogel V-Mg-hydroxide samples was found to be as high as1000-1100 m 2 /g, regardless to concentration of vanadium introduced. It was suggested thatthe high-dispersed V-component is evenly distributed on surface of MgO as amorphousvanadate. Catalytic tests in ODHP reaction revealed that the aerogel VO x /MgO samples are1.5-2 times more active as compared with similar catalysts prepared by mechanical mixingand impregnation methods.The selective oxidation of light hydrocarbons to valuable intermediates via catalyticoxidative dehydrogenation (ODH) is of great interest for petrochemical industry and has beenstudied extensively. The ODH reaction is believed proceed by mechanism in which adsorbedalkane reacts with lattice oxygen and the reduced oxide interacts with adsorbed, dissociatedoxygen. VO x /MgO system is well known as an efficient catalyst for oxidativedehydrogenation of short chain alkanes (ethane, propane, butane). The most widely usedmethods for preparation of VO x /MgO catalysts are coprecipitation of V- and Mg-salts andimpregnation of MgO support with diverse V-precursors. For impregnation method, the ratherhigh butadiene-1,3 yields were obtained for VO x species supported on nanocrystalline aerogelMgO-AP (Autoclave Prepared) support as compared with conventional metal oxides [1, 2].In the present work, the new approach for the synthesis of nanoscale aerogel VO x /MgOcatalysts has been suggested. In short it includes formation of Mg(OCH 3 ) 2 via reaction of Mgwith methanol, dilution with toluene, addition of vanadium isopropoxide, gel formation byhydrolysis, supercritical drying of resultant suspension, and conversion of aerogel V-Mghydroxideinto VO x /MgO via heat treatment under vacuum at 500 °C overnight and ultimatecalcination in air at 550 °C for several hours. It was found that the developed aerogeltechnology allowed us to synthesize the mixed V-Mg-hydroxides with a surface area as highas 1000-1300 m 2 /g. The interim stage of vacuum dehydration of V-Mg-hydroxides wasapplied to convert the aerogel V-Mg-hydroxides into VO x /MgO catalysts with a final surfacearea of about 350 m 2 /g, which is superior to analogues found in literature [1-3].312