Semi-industrial-scale silicalite-1 membranes for n-butane/methane separation

The semi-industrial-scale tubular silicalite-1 membranes with a thickness of 8.4–8.9 µm were prepared and used for the separation of n-butane/methane mixture for the first time. The membranes remained highly [h0h] oriented. The effects of temperature, pressure and feed flow rate (Reynold numbers) on the separation performance for the 6-cm-long and 50-cm-long membranes were investigated. Separation stability of the semi-industrial-scale tubular silicalite-1 membrane was studied. The short silicalite-1 membranes displayed the highest n-butane/methane separation factor of 935 among the literature data so far and a permeance of n-butane of 0.5 × 10⁻⁸ mol/(m² s Pa) at 243 K. Two long silicalite-1 membranes showed n-butane permeances of 3.1 × 10⁻⁸ and 1.9 × 10⁻⁸ mol/(m² s Pa) and n-butane/methane separation factors of 72 and 110 at 298 K in the 10/90 mol% n-butane/methane mixture, respectively. The results displayed that silicalite-1 membranes have great potential application for removal of n-butane from natural gas mixtures.