Process for manufacturing catalysts containing copper, zinc and aluminum, useful for producing methanol from synthesis gas

A process for manufacturing a catalyst precursor of essentially homogeneous composition, containing at least copper, zinc and aluminum as essential elements, characterized by the following steps of:

• (a) contacting a solution of at least one alkali metal compound selected from the group consisiting of bicarbonates, carbonates and hydroxides with an essentially homogeneous solution containing, as salts and/or soluble complexes, at least copper, zinc and aluminum metals, said contacting step being performed at a pH of about 6.3-7.3, so as to form an amorphous homogeneous precipitate, having a flat diagram in X-ray diffraction, of at least copper, zinc and aluminum metals, the residence time of said precipitate in the mother liquors being from 0.1 to 30 minutes,
• (b) washing with water the precipitate obtained in step (a) until its content by weight of alkali metals is reduced to about 0.1-0.3% weight of the metals present,
• (c) drying and then roasting the washed precipitate obtained in step (b) so as to convert it to a mixture of oxides,
• (d) crushing said mixture of oxides to particles of a size smaller than about 0.5 mm, when the particle size of the mixture of oxides from step (c) is greater than 0.5 mm,
• (e) forming an aqueous suspension of the mixture of oxides of particle size smaller than about 0.5 mm,
• (f) washing the suspension of oxides obtained in step (e) by means of an aqueous solution of acid, said solution having a pH lower than about 6.7, so as to reduce its alkali metals content to less than about 0.05% by weight of the metals present,
• (g) separating the mixture of dealkalinized oxides obtained in step (f) from the washing waters.