Preparation of polydopamine-derived carbon-based nano-Fe catalysts and its catalytic conversion of toluene for hydrogen production

• Catalytic cracking of toluene with PDA porous carbon increases hydrogen production. • The concentration of activated steam has a positive influence on the surface area. • More C-O functional groups are more likely to have n-π interaction with toluene. Carbon-based metal catalysts have excellent catalytic performance due to their porous structure and high dispersion of metal particles. In this paper, polydopamine (PDA) microspheres as carbon supports and Fe as the metal phase are used to synthesize carbon-based nano-Fe catalysts for catalytic cracking of toluene. The PDA derived carbon-based metal catalysts has more regular spherical shape when compared with biomass derived catalyst. The effect of activation steam concentration and Fe load on the characteristics of catalyst have been studied. As the concentration of activated steam increases from 7.5% to 15%, the specific surface area of the carbon support increases significantly, and the number of micropores also increases. When the Fe impregnation concentration is less than 5%, the dispersion of the metal particles on the surface of the carbon support is very good, and when the Fe impregnation concentration is greater than 5%, the metal particles on the surface of the carbon support begin to agglomerate. The introduction of this catalyst can significantly increase the removal efficiency of toluene and the hydrogen content of tail gas. The carbon-based metal catalysts before and after the toluene catalytic cracking experiments are characterized and found that the microporous structure played an important role in the removal of toluene, and the C─O functional groups and ─OH groups on the catalyst surface also played an important role in the catalytic process. The addition of Fe species can increase the specific surface area and promote the formation of surface functional groups, and can also strengthen the π-π interaction and electrostatic interaction on the catalyst surface. The lattice oxygen introduced by iron oxide can provide oxygen source for the oxidation reaction of toluene.