A method for preparing a silica-modified catalyst support is described including: (i) applying an alkyl silicate to the surface of a porous support material in an amount to produce a silica content of the silica-modified catalyst support, expressed as Si, in the range 0.25 to 15% by weight, (ii) optionally drying the resulting silicate-modified support, (iii) treating the support with water, (iv) drying the resulting water-treated support, and (v) calcining the dried material to form the silica-modified catalyst support.