Preparation of Pd-B/γ-Al2O3 amorphous catalyst for the hydrogenation of tricyclopentadiene

Pd-B/γ-Al2O3 amorphous catalysts were prepared through impregnation and KBH4 reduction for the hydrogenation of tricyclopentadiene. The effects of reduction conditions, pre-calcination and thermal annealing on the hydrogenation activity were studied. It is found that the reduction should be conducted in ice water batch with KBH4 solution added by dropping to avoid the crystallization of amorphous metals. Pre-calcination of the catalyst before reduction can increase the amount of Pd on the prepared catalyst. With pre-calcination at 200 °C, the highest hydrogenation turnover frequency is obtained. The amorphous catalyst is thermally stable at temperature below 150 °C. When annealed at higher temperature, the amorphous metals are gradually crystallized and the particle size is increased. After annealing at 600 °C, the catalyst is uniformly crystallized. It is noticed that the size of amorphous Pd calculated from H2-adsorption is much smaller than the actual size observed by transmission electron microscope (TEM). This indicates that amorphous metal has stronger H2-adsorption ability than crystal metals with comparative particle sizes. The hydrogenation activity decreases with the increase of annealing temperature. Moreover, the hydrogenation activity is solely dependent on the amount of H2-adsorption, suggesting that the excellent performance of amorphous catalyst should be attributed to their better H2-adsorption ability.

Graphical abstractThe preparation conditions have significant effect on the properties and activity of Pd-B/γ-Al2O3 amorphous catalyst. The amorphous catalyst is thermally stable at temperature below 150 °C and shows stronger H2-adsorption capacity than crystallized metals with comparative surface. It exhibits high activity for the hydrogenation of tricyclopentadiene (TCPD) and a linear relationship is observed between the activity and amount of H2-adsorption.Figure optionsDownload full-size imageDownload as PowerPoint slide