Straight-run crude oil of gas condensate naphtha cuts for use as components of motor fuels must be refined: to transform their low-octane components - n-paraffins - into high-octane compounds, while not decomposing isoparaffins if possible. A catalyst with high molecular-sieve selectivity with respect to conversion of n-paraffinic hydrocarbons and high catalytic stability is required for this. These requirements are satisfied by high-silica zeolites form the pentasil family [1 -5].