Carbon dioxide as an alternative solvent for the direct synthesis of hydrogen peroxide: A review of recent activities

The importance of the direct synthesis process for the production of hydrogen peroxide from hydrogen and oxygen is apparent from the numerous publications and patents on the subject since the beginning of the 20th century. The prospects it would open up for various hydrogen peroxide applications are undeniable. However, the challenges with which the process has to cope are not to be underestimated. Besides the development of different reactor concepts, one attempt to address the issues concerning safety, activity, selectivity and cost, is the search of alternative solvents. Deploying dense carbon dioxide as solvent is a possibility investigated in recent years. Carbon dioxide would be an environmentally friendly alternative and would also offer benefits in terms of enhanced solubility for the reactants as well as diffusivity. This review summarizes the proposed concepts for CO2 as medium for the direct synthesis process of hydrogen peroxide and the challenges going along with it. Relevant properties of CO2 for this particular process together with some economic aspects will be discussed as well. (C) 2014 Elsevier B.V. All rights reserved.