The present invention pertains to a process for regenerating a used additive-based catalyst comprising the step of regenerating the catalyst by contacting it with an oxygen-containing gas at a maximum temperature of 500° C. Preferably, the maximum catalyst temperature during the regeneration step is 300-500° C., more preferably 320-475° C., even more preferably 350-425° C. The regenerated additive-based catalyst obtained with the process according to the invention has a higher activity than an additive-based catalyst regenerated at a higher temperature. Additionally, its activity is also higher than that of a corresponding catalyst, which never contained an additive.