Supplementary material from "Secondary metal species gathered on Ni-modified Al2O3 nanflower to achieve synergetic catalytic epoxidation of styrene"

The styrene epoxidation to afford its epoxides shows a promising approach for value-added chemicals construction. By virtue of Ni-modified AlOOH nanoflower as starting materials, secondary adsorption and thermal treatment make the composite transformed into Co/Cu coupled with NiO-modified Al2O3 nanoflowers. The results indicate that the Ni-modified makes the structural properties of AlOOH improved and regulates the morphology, while calcination treatment contributes to the surface area enlargement and hierarchical pore structure formation, which benefits to the diffusion and accessibility of reactant molecule approaching reactive sites. The secondary introduced metal including Cu/Co affords a well-dispersed state close to the in-situ formed NiO over the Al2O3 nanoflowers. It was found that the Co-modified catalyst Al2O3(Ni)-Cu exhibited the highest styrene conversion rate and styrene oxide selectivity compared to the Co-modified Al2O3(Ni)-Co and Al2O3(Ni). In addition, the Al2O3(Ni)-Cu further showcases the great potential in the selective benzene oxidation to benzoquinone, in which benzene conversion reach 60 % at 10 h, the benzoquinone selectivity was more than 90 %, with near 1448 μmol yield. This finding indicates that copper and nickel species exert synergistic effects by electronic interactions between bimetals to influence final products generation, which provides valuable references for further research in related fields.