Formic acid dehydration using mechanochemically prepared TiO2‐graphite composites

Commercial high surface area graphite (HSAG300) and commercial TiO 2 were used to produce composite materials through a simple mechanochemical method involving milling and ultrasonic treatments. The acid and basic sites exposed on the surfaces of these materials were characterized by temperature‐programmed desorption (TPD) of ammonia and carbon dioxide. The catalytic materials were tested in the dehydration reaction of formic acid to produce hydrogen‐free CO. While HSAG300 is practically inactive under reaction conditions (continuous gas flow at temperatures in the range of 100–250 °C), all samples containing TiO 2 are active, exhibiting high selectivity to CO without significant deactivation at moderate reaction temperatures. It is demonstrated that the presence of graphite in the catalysts enhances the specific catalytic activity of TiO 2 . Assuming that the dehydration reaction is catalyzed by acid sites on the TiO 2 surfaces, a comparative evaluation of the surface sites reveals that the graphite‐TiO 2 interactions not only change the density of surface sites but also modify the strength of the acid centers of TiO 2 . In summary, the interaction of HSAG300 with TiO 2 modulates the surface properties of the prepared composite catalysts, decreasing the total number of basic surface sites and increasing the strength of acidic sites compared to bare TiO 2 .