Isomerization and hydrocracking of C9 through C16 n-alkanes on Pt/HZSM-5 zeolite

The pure n-alkanes with 9 to 16 carbon atoms were converted on a Pt/HZSM-5 zeolite in the presence of hydrogen. The products formed by isomerization and hydrocracking were analyzed by high-resolution capillary GLC. The product distributions differ substantially from those observed earlier on Y type zeolites. Isomerization on Pt/HZSM-5 gives mainly monomethyl isomers. The cracked products consist of n- and i-alkanes with a single methyl branching. Neither methane nor ethane are formed which is indicative of an ionic mechanism of cleavage. The carbon number and isomer distributions of the cracked products are best interpreted in terms of a so-called type C β-scission mechanism combined with secondary isomerization and competitive adsorption at the acidic sites inside the Pentasil channel system.