268 ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 2, pp. 268 271. Pleiades Publishing, Ltd., 2007. Original Russian Text D.B. Tagiev, R.V. Starikov, A.A. Imanova, M.I. Rustamov, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 2, pp. 269 272. CATALYSIS Isomerization of n-Butane on Dealuminated Mordenite Promoted with Zirconium Dioxide D. B. Tagiev, R. V. Starikov, A. A. Imanova, and M. I. Rustamov Mamedaliev Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan Received June 21, 2006 Abstract Zirconiun dioxide promotes the catalytic activity of a dealuminated mordenite in n-butane isomer- ization. A method is suggested for preparing, without any solvents, a sulfated mordenite-zirconium catalyst active at relatively low temperatures. DOI: 10.1134/S107042720702019X Isomerization of n-butane is one of the most im- portant processes of petrochemical industry in produc- tion of alkylates and other valuable products [1, 2]. To perform this reaction, different heterogeneous cat- alysts have been suggested. Among them the chlori- nated platinum-alumina catalysts, metallozeolites, and sulfated zirconium dioxide are of particular interest [1 8]. Each of these catalysts has advantages and dis- advantages. For instance, chlorinated platinum-alumi- na catalyst require a thorough pretreatment of the raw material and are environmetally unfavorable. Iso- merization with metallozeolites is performed at high temperatures; they are favorable in isomerization of C 5 and C 5 C 6 paraffins. Sulfated zirconium dioxide is active at relatively low temperatures. However, additional studies are required to improve the stability and reproducibility of its catalytic properties. Due to cellular structure and possibility of purpose- ful modification of the physicochemical properties, zeolites are promising catalysts for n-butane iso- merization. It was shown in [9, 10] that dealumina- tion of H-mordenite enchances its isomerization ac- tivity. The activity of dealuminated H-mordenite can be further raised by choosing appropriate promoters [11, 12]. In this study, we examined the catalytic properties of binary mordenite-zirconium and ternary sulfated mordenite-zirconium catalysts to find the probable synergism of such systems and to develop on their base low-temperature catalysts of n-butane isomeriza- tion. EXPERIMENTAL The catalysts were prepared from dealuminated H-mordenite with the SiO 2 /Al 2 O 3 ratio of 17 (sample HM 17 ). To promote HM 17 with zirconium dioxide, we used impregnation and mechanical mixing of the zeo- lite with ZrO(NO 3 ) 2 or ZrO(OH) 2 , with subsequent decomposition of the mixture at 823 873 K [the sam- ples were denoted as a ZrO 2 /HM 17 (impregnation) and HM 17 a ZrO 2 (mixing), where a is the ZrO 2 content, wt %]. The samples obtained were sulfated by their treatment with 2 M solution of (NH 4 ) 2 SO 4 . Catalysts were molded with aluminum hydroxide as a binding agent, dried at 383 393 K, and calcined at 823 873 K. The conversion of n-butane was studied in a flow- type apparatus at atmospheric pressure within the 433 523 K range. A 2 cm 3 portion of cylindrical catalyst granules 1 3 mm in size was charged into a quartz re- actor and activated in an air flow at 773 K for 3 h. After the experiments, the catalyst was regenerated under the same conditions. After activation or regen- eration, catalysts were cooled in an N 2 flow to the re- action temperature, and n-butane was started to be delivered at a flow rate of 300 ml h 1 . No carrier gas was used. The induction period of the reaction was 20 30 min, depending on the experimental conditions. During this time, the isobutane yield reached the max- imum and then decreased to a constant value. The data reported in this paper are related to 20th minute of the reaction run. The reaction products were monitored chromatographically, and catalysts, by powder X-ray