Process of prolonging the life of ester hydrogenation catalyst

In the process of preparing ethylene glycol by hydrogenating a mixture comprising glycolic acid esters with more than 22% of the esters in the form of polyglycolide esters in the presence of a hydrogenation catalyst, the improvement of extending the life of said hydrogenation catalyst, which comprises heating said mixture to a temperature in about the range 300.degree.-525.degree. F., before hydrogenating it, with from 250 to 400 mol % excess of alcohol based on polyglycolide esters for a period of 20-90 minutes to transesterify said mixture and thereby lowering the polyglycolide ester content below about 22%, the aforesaid percentages being by weight based on the total ester content.