III International Conference

PP-II-134АLTERNATIVE APPROACH TO DESIGN OF SUPPOTED VPO/SILICA CATALYSTSSydorchuk V.V., Diyuk E.A., Zazhigalov V.A., Konovalova N.D.Ukrainian-Polish Laboratory of Catalysis, Institute of Sorption and Problems ofEndoecology, NAS of Ukraine, Kyiv, UkraineE-mail: bilychi@online.com.ua, zazhigal@ispe.kiev.uaThe deposition of catalyst active phase on support permits to increase a mechanicalstrength of catalyst, specific surface area and improves a porous structure of the sample andetc. However, the number of publications described the synthesis of supported VPO catalystsactive in reactions of paraffins transformations is limited. The deposition of active mass onsupport by traditional methods e.g. impregnation, precipitation, grafting, CVD don’t permit toobtained the systems with catalytic properties comparable to bulk catalysts. The main reasonof this fact is the formation on support surface vanadium (IV, V) phosphate phases instead ofhemihydrate vanadyl hydrophosphate (VOHPO 4 0.5H 2 O) precursor of catalyst selective inoxidation processes.The alternative method of the synthesis of supported VPO/silica catalysts was developedin this work. The method includes three basic stages:i) Preparation of silica aerogel with the homogeneously-mesoporous structure byhydrothermal method from the fume silica A300.ii) Barothermal modification of surface of prepared aerogel by different organiccompounds. The citric acid, salicylic acid, oxalic acid, 1,4-butandiol, benzyl alcohol and 1-butanol were used as the modification agents. It is necessary to note that some of thesecompounds are used as reducing agent in traditional synthesis of bulk VPO catalyst. Thehexamethyldisiloxane which adds the hydrophobic properties to surface was used also.iii) Simultaneous barothermal synthesis of active VPO phase and its deposition onsupport. The modified support, V 2 O 5 , H 3 PO 4 and organic medium (1-butanol) were loaded toautoclave and process of synthesis was carried out at 170 °C.The prepared samples were studied by means of XRD, DTA, SSA, porosimetry, IRspectroscopymethods. Also, the activity of VPO/SiO 2 catalysts in oxidative dehydrogenationof propane was determined.It was established that developed method of catalyst synthesis permits to prepare thesupported crystalline phase VOHPO 4 0.5H 2 O. The nature of modification agent regulates theratio of crystallographic planes I 001 /I 200 of VOHPO 4 0.5H 2 O. It is well-known, that the409