Gradient porous biochar materials with high specific surface area as supports for Pd/C catalysts for efficient maleic acid hydrogenation

The poor textural properties of initial biochar materials have hindered their extensively applied as catalyst supports. Herein, cellulose biochar materials with the gradient porous and high specific surface area were synthesized by adding different ratios of ZnCl2, and as supports to prepare Pd/Ccel catalysts for efficient maleic acid hydrogenation in water. The characterization results indicated that the textural propertiesand dispersion of Pd in Pd/Ccel catalysts depended on the ratio of ZnCl2 to cellulose. The Pd/CcelZnCl2(1:3) catalyst exhibited the best catalytic activity among all catalysts and outstanding stability for reusing 8 times under mild conditions (60 °C, 2 MPa). In addition, this synthesis strategy was also suitable for other biomass materials (glucose, sucrose, and starch) and the catalytic performance of ZnCl2-modified Pd/C catalysts in maleic acid hydrogenation reaction also improved dramatically. The carbonization mechanism was discussed by TG-MS and the results illustrated that ZnCl2 reduced the carbonization temperature and altered the pyrolysis behavior of biochar as a result of excellent catalytic behavior. This work provided a facile and universal strategy for synthesizing biochar high-efficient supported catalysts with gradient porous structure and high specific surface area.