Abstract
A solid superacid catalyst with an acid strength of H0⩽–14.52 was obtained by impregnating Zr(OH)4 or amorphous ZrO2 with aqueous ammonium metatungstate followed by calcining in air at 800–850 °C (13 wt.% W); this catalyst was active for the isomerisations butane to isobutane at 50 °C, and pentane to isopentane at 30 °C.