Effect of crystallinity on the catalytic performance of amorphous Co–B particles prepared from cobalt nitrate and potassium borohydride in the cinnamaldehyde hydrogenation

The amorphous Co–B particles were prepared from cobalt nitrate and potassium borohydride. Ethanol-thermal treatment has been used to promote the crystallinity of Co–B particles. Both the amorphous and crystallized Co–B particles were characterized by X-ray powder diffraction (XRD), scanning electron micrograph (SEM), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), specific surface area (SBET), CO temperature-programmed desorption (TPD), and magnetic performance test. After crystallization, the synergistic effect between Co and B, the structure stability, and the magnetic property of Co–B enhanced while the activation energy in cinnamaldehyde (CMA) hydrogenation decreased. Furthermore, the conversion of cinnamaldehyde (CMA) increased from 5% to 57%. The hydrogenation of the CC bond in cinnamaldehyde (CMA) is favored for the amorphous Co–B particles while the hydrogenation of the CO bond is preferred for the crystallized Co–B particles. After 13 cycles, the crystallized Co–B particles remain higher cinnamaldehyde (CMA) conversion and cinnamyl alcohol (CMO) selectivity, which is attributed to their good structure stability and the novel magnetic method for recycle; while the cycle performance of amorphous Co–B particles is poor due to their instable structure.

The hydrogenation of the CC bond in cinnamaldehyde (CMA) is favored for amorphous Co–B while the hydrogenation of the CO bond is preferred for crystallized Co–B. The cycle performance of crystallized Co–B is better than that of amorphous Co–B, which is attributed to the more stable structure for crystallized Co–B. Figure optionsDownload as PowerPoint slide