from first principles PP-I-1

PP-III-15Supported Heteropoly Acids as Catalysts for Paraffin IsomerizationBykhovskii M.Ya., Shibanova M.D., Udalova O.V., Shashkin D.P., Korchak V.N.Semenov Institute of Chemical Physics RAS, Moscow, Russiaolga_udalova@mail.ruIsomerization of n-paraffins over heterogeneous catalysts is one of the efficient ways formotor fuels upgrading, as well as for production of various organic compounds.In the present work the results of n-hexane isomerization at temperature range 270 - 330 o Care established. Silica supported P-Mo, P-W, Si-Mo and Si-W type heteropolyacids (HPA)were applied as catalysts in this study. In particular, H 3 [PMo 12 O 40 ] - HPA-1; H 3 [SiMo 12 O 40 ]-HPA-2; H 4 [PW 12 O 40 ]- HPA-3 and H 4 [SiW 12 O 40 ]- HPA-4 were synthesized.Testing of catalytic activity was conducted over the samples with about 20% (wt.) ofsupported HPA. It was found that P-Mo and Si-Mo heteropolyacids (HPA-1 and HPA-2) didnot show any substantial activity in n-hexane isomerization. However, P-W and Si-Wheteropolyacids (HPA-3 and HPA-4) demonstrated somewhat higher activity than those ofHPA-1 and HPA-2. For instance, yields of isomerization products (2-methylpentan and3-methylpentane) over HPA-3 and HPA-4 were 0.8 and 2.4%, respectively.Addition of Ni to silica supported HPA samples in amount 2% (wt.) drastically increased theiractivity with respect to isomerization products formation. Among them HPA-4 showed thebest catalytic performance providing yield of isomerization products 25.5% at selectivity82.5%.Substantial increase of catalytic activity observed for Si-W HPA is due to higher acidity thanthat of other HPA samples [1]. Introduction of Ni enhanced the rate of dehydration stage ofentire isomerization process [2] to form surface hydrogen atoms.References:[1] Y.Izumi, R. Hasebe, K. Urabe, J. Catal. 84 (1983) 402[2] J. Mills, H.Heinemann, T.Milliken, A.Oblad, Ind. Eng.Chem. 45 (1953) 134166