Ukrainian Mordenite–clinoptilolite Rocks As a Base for Linear Hexane Isomerization Catalyst

The ways of preparation of the linear hexane hydroisomerization catalysts on the base of mordenite–clinoptilolite rocks of Ukrainian deposits are described: under the strictly defined conditions of thermic and acidic treatments of parent rocks, followed by palladium (0.5wt%) introduction, the samples of catalysts were synthesized which are well comparable with the catalysts on the base of synthetic mordenite. The high efficiency of the samples synthesized was achieved due to the appropriate degrees of the residual crystallinity of the mordenite–clinoptilolite rocks modified as well as due to the corresponding strong acidic sites content of their zeolitic components. The isomerization mechanism through the hexane molecules protonation resulting in the formation of non-classic carbonium ions, which include the pentacoordinated carbon atoms, with subsequent dehydrogenation of these structures over Lewis acidic sites is proposed – the role of Lewis acids play probably palladium and extraframework aluminum. Based on the consideration of the different proton affinity of various C6H14 isomers, the plausible pathways to the formation of definite hexane isomers are discussed. These routes give such sets of individual branched hexanes which consist both the thermodynamically predicted and really found isomerizate compositions.