Nickel based catalyst supported by carbon aerogel prepared from waste pomelo peel to crack ethanol for hydrogen production: Catalytic performance and mechanism

Hydrogen, a clean energy, has been widely used, whose preparation methods is significant for developing. Herein, carbon aerogel (CA) was prepared via hydrothermal-carbonization from waste pomelo peels to support Ni catalyst, and cracked ethanol for hydrogen production. When the reaction temperature reached 700 degrees C and the Ni loading rate was 2 wt%, the most effective catalytic conditions were achieved. In this situation, H2 yield can reach 76.01 wt%. The mechanism of Ni/CA catalyst performance during ethanol cracking was revealed: The catalysts' evolution during the reaction of ethanol catalytic cracking can be divided into three stages: enhancement stage, stabilization stage, and deactivation stage. During the first stage (Enhancement stage), the pores of the catalysts developed and more Ni was exposed because of the functional group breaking and the polycondensation of carbon, which enhanced the H2 generation. The Ni on the catalyst surface was slightly promoted in the preliminary period of the second stage (Stabilization stage) and ordered graphite fibrous carbon started to grow. These two processes kept in balance, which led to the generation of hydrogen kept increasing. As the reaction proceeded further, graphite carbon gradually blocked the pores and covered the catalytic active substances loaded on the surface. During the last stage (Deactivation stage), the performance of the catalyst had been greatly reduced by carbon deposition, and the generation of H2 was thus inhibited.