Process for separating one or more components from a mixture

A process for separating a homogeneous catalyst system that contains at least one metal from groups 8 to 10 of the periodic table of elements or a compound thereof and a phosphorus-containing ligand, from a reaction solution by a membrane separation, the process comprising:

• adding an acid to the reaction solution, to obtain a mixture, and
• separating the mixture by membrane separation, to result in the homogeneous catalyst system being depleted in the resulting permeate stream and enriched in a resulting retentate stream,
• wherein at least one component of the homogeneous catalyst system contains at least one basic functional group,
• wherein the acid is added in an amount of ≥0.1% by weight, based on the total weight of the mixture, wherein the at least one component to be separated has a basic functional group, and
• wherein the acid is a Brønsted or Lewis acid, the Brønsted acid being selected from the group consisting of perchloric acid sulfuric acid, phosphoric acid, methylphosphonic acid or a sulfonic acid and the Lewis acid being selected from the group consisting of aluminium triflate, aluminium chloride, aluminium hydride, trimethylaluminium, tris(pentaflurophenyl)borane, boron trifluoride, boron trichloride, titanium(IV) isopropoxide, BU2SnO, BuSn(O)OH, or mixtures thereof.