Based On Ultrasonic Technology Of Amorphous Alloy Catalytic Selective Hydrogenation Of Cinnamaldehyde Cinnamyl Alcohol

The amorphous alloy is a kind of material with short-range ordering while long-range disordering structure. Its unique structural character results in the excellent catalytic properties, such as the high catalytic activity and selectivity, the high resistance to the sulfur poison, especially the less environmental pollution occurred during the catalyst preparation, which is of special significance for the development trend of current chemical engineering. Parallel with the catalyst design, there is strong driving force to explore more convenient procedures to prepare more powerful catalysts. One of the most promising tools recently introduced in heterogeneous catalysis is the application of ultrasonic irradiation. The presonication of the catalyst was found to be highly efficient in the increase of the reaction rate.The ultrafine Co-B amorphous alloy catalyst was prepared by chemical reduction of CoCl2 with borohydride in aqueous solution. The presonication of catalyst was performed before the reaction, which was found to be highly beneficial for the activity of the Co-B amorphous alloy catalyst during liquid phase hydrogenation of cinnamaldehyde (CMA) while the selectivity to cinnamyl alcohol (CMO) was also slightly improved. The reaction rate was increased by 140% and the CMO yield was enhanced by 67% with a suitable presonication time. However, presonication for very long time resulted in the decrease in the activity of the Co-B amorphous catalyst. Various characterizations, such as XRD, DSC, TEM, XPS etc., demonstrated that the presonication had no significant effect on the nature of the active sites, which could account for the facts that both the activity per m2 of the BET surface area and the selectivity to CMO remained almost unchanged during the presonication. The increase in the activity of the Co-B amorphous catalyst was mainly attributed to the increase of its BET surface area owing to the dispersing effect of ultrasounds. Very long presonication was harmful for the activity since the BET surface area decreased due to the gathering of the Co-B alloy particles caused by the local high temperatureand the collision resulted from the "bubble effect" and the "microwave jet" of the ultrasounds.The Co-B/SiO2 amorphous catalyst was prepared via impregnation following the chemical reaction with or without presonication before the liquid phase hydrogenation. In comparison with the catalyst without presonication, the reaction rate was 1.86 times and the selectivity of CMO was increased by 121%. Similar to those found over the ultrafine Co-B amorphous alloy catalyst, long presonication also resulted in the decrease in the activity of the Co-B/SiO2, which could also attributed to the decrease of surface active are caused by the gathering of the particles at long presonicationThe Ru-B amorphous alloy catalyst was also prepared by chemical reduction, which was used for the title reaction even at normal temperature and pressure owing to its extremely high activity. The presonication of the Ru-B catalyst was beneficial for catalytic activity. The CMO yield was enhanced by 13% after presonication at suitable time. The optimum sonication time was determined as 15min. Extremely long presonication was detrimental for the activity due to the cause as described above.