2010, №1

сс. 63-72

Transformation of n-alkanes over H-forms of zeolites under supercritical conditions

2010, №1

сс. 63-72

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V.I. Bogdan, A.E. Koklin, Ya.A. Pokusaeva, V.B. Kazansky

Key words: isomerization, n-alkanes, zeolite catalysts

The skeletal isomerization of n-butane, n-hexane and n-heptane in the supercritical (SC)  conditions is studied over H-forms of zeolites (mordenite, beta, ZSM-5) at 260÷450  °C and 80÷130 bars. The isomerization of n-hexane  and n-heptane is accompanied by such  side processes as oligomerization and cracking. Selectivity with respect to the  formation of branched isomers of these hydrocarbons does not exceed 70 and 30  %, respectively. ZSM-5 is shown to be the most durable catalyst, however  selectivity towards the formation of branched isomers does not exceed 30 % even  at 260—280 °C; it decreases down to 3 % at 400—450 °C. The fraction of  aromatization products in these conditions does not exceed 15 %. The effect of  the addition of C6—C7 n-alkanes onto the  isomerization of n-pentane over H-mordenite in SC conditions (260 °C, 120  bars) is studied. It is demonstrated that the gradual decrease of activity is  due to the formation of higher hydrocarbons.

doi:10.1134/S1990793110070067