Acid properties of phosphoric acid activated carbons and their catalytic behavior in ethyl-tert-butyl ether synthesis

Carbon catalysts were prepared by phosphoric acid activation of styrene–divinylbenzene copolymer followed by liquid phase oxidation with nitric acid. Their surface properties were modified by heat treatment at 300–600 °C in an argon atmosphere, and their acid properties were characterized by quasi-equilibrium temperature desorption of ammonia and by acid–base titration. The pore structure was characterized by nitrogen adsorption at −196 °C. Their catalytic activity in the synthesis of ethyl-tert-butyl ether (ETBE) from isobutene and ethanol was investigated. It has been shown that the carbon catalysts are active and selective in ETBE synthesis. The main factor determining the catalytic activity of carbon catalysts is the total number of acid surface sites. A linear correlation between total amount of surface sites and catalytic activity was found.