Abstract:

A kind of Janus amphiphilic carbon silicon double skeleton nanomaterial C_xN_y@mSiO₂ consisting of inner cavity, hydrophobic nitrogen doped carbon inner layer and hydrophilic silicon dioxide outer layer was successfully prepared. Ni-B alloy nanoparticles were loaded on amphiphilic carbon-silicon nanomaterials for the first time to prepare Ni-B/C_xN_y@mSiO₂. The catalyst was also used for the aqueous phase hydrogenation of rosin. The structure of the catalyst was analyzed and characterized by SEM, TEM, N₂ adsorption-desorption, XRD and XPS. The results of structural analysis showed that the catalyst had a hollow structure of nanomaterials with large specific surface area, which was conducive to mass transfer and substrate enrichment. The doping of N atoms in the inner carbon skeleton made the additional metal nanoparticles attached, and the fine Ni-B amorphous alloy particles were uniformly dispersed in the C_xN_y@mSiO₂ hollow nanospheres and mSiO₂ shell layers. The hydrophilic silica shell could improve the stability and dispersion of the catalyst. In the water/oil two-phase reaction system, the amphiphilic nano catalyst as a solid foaming agent greatly promoted the dissolution of H₂ and the contact with the substrate. The synergistic effect between Ni and B atoms could significantly improve the catalytic activity. Therefore, the non noble metal Ni-based nano catalyst showed good catalytic activity for rosin hydrogenation, and its catalytic activity was basically equivalent to those of noble metal Ru and Pd catalysts. Under the conditions of 160 ℃, 4.0 MPa, 4 h, water oil volume ratio of 1∶2 and catalyst dosage(based on rosin mass) of 10%, the conversion rate of rosin was 98.77%, the selectivity of tetrahydroabietic acid was 23.89%, and the GC content of dehydroabietic acid was less than 1%, indicating that the product reached the standard of Grade I hydrogenated rosin. The developed amphiphilic Ni-B nano catalyst showed stability and good reusability. When it was reused for 6 times, its catalytic activity did not decrease significantly.

Key words: water-phase hydrogenation, amphipathy, Ni-B alloy, rosin