Method of regenerating ruthenium catalysts suitable for hydrogenation

An integrated method for hydrogenating a substance comprising aromatic groups consisting of the following steps:

• a) Providing a substance comprising aromatic groups and a ruthenium catalyst, wherein the ruthenium catalyst is selected from among the following groups:
• i) A catalyst comprising, as active metal, either ruthenium alone or ruthenium together with at least one metal of transition group IB, VIIB or VIII of the Periodic Table of the Elements in an amount of from 0.01 to 30% by weight, based on the total weight of the catalyst, applied to a support, wherein from 10 to 50% of the pore volume of the support is formed by macropores having a pore diameter in the range from 50 nm to 10000 nm and from 50 to 90% of the pore volume of the support being formed by mesopores having a pore diameter in the range from 2 to 60 nm, with the sum of the pore volumes being 100%;
• and
• ii) A coated catalyst comprising, as active metal, either ruthenium alone or ruthenium together with at least one further metal of transition group IB, VIIB or VIII of the Periodic Table of the Elements applied to a support comprising silicon dioxide as support material, wherein the amount of active metal is <1% by weight, based on the total weight of the catalyst, and at least 60% by weight of the active metal is present in a shell of the catalyst to a penetration depth of 200 μm determined by means of SEM-EPMA (EDXS);
• b) Hydrogenating the substance by contact with hydrogen in the presence of the ruthenium catalyst until the catalyst has a reduced hydrogenation activity,
• c) Regenerating the catalyst consisting of flushing with inert gas until an activity of >90% of the original activity has been attained, and
• d) Optionally, repeating the steps a) to c),
• wherein the pressure applied during flushing is from 0.5 to 5 bar;
• and
• wherein regenerating the catalyst according to step c) is carried out without removing the catalyst from the same reactor in which the hydrogenation according to step b) takes place.