Behavior of Hydrogen Transfer in the Hydrogenation of Anthracene over Activated Carbon

Abstract

The behavior of hydrogen transfer over activated carbon was examined through the hydrogenation of anthracene in the temperature range of 300−400 °C with three kinds of hydrogen sources: hydrogen gas, hydrogen-donor tetralin, and the combination of both. With hydrogen gas, the hydrogen transfer rate determined from the distribution of hydrogenated anthracene products increased with both hydrogen partial pressure and temperature, while in tetralin it depended on the concentration of hydrogen atoms formed on the surface of activated carbon by the dehydrogenation of tetralin and reached levels at temperatures of 350−400 °C comparable to those obtained in the same temperatures under 6.0 MPa of H2. When both hydrogen gas and tetralin were used together, the hydrogen transfer rate was higher than each one obtained separately with hydrogen gas alone or tetralin alone, but much lower than the simple sum of both rates in the range of 350−400 °C. Simultaneously, the hydrogen formation rate based on the conversion of tetralin in this case was greatly suppressed due to the presence of hydrogen gas and measured to be quite close to the corresponding hydrogen transfer rate. This indicates that the hydrogen transfer in the hydrogenation of anthracene over activated carbon mainly took place from tetralin to anthracene when both hydrogen gas and tetralin donor were used as hydrogen source together.