Study On Supported Nano Amorphous Catalysts And Hydrogenation To Aromatic Alcohol By Aromatic Ketone

Aromatic alcohols,as essential fine chemical products,are widely used in pharmaceutical and perfume industries.Aromatic ketone hydrogenation has the advantages of high atom utilization rate,non-polluting raw materials,etc.This aromatic alcohol synthesis process has great development prospects.However,the Raney Ni catalyst used in industrial hydrogenation of aromatic ketone has problems such as low selectivity and poor safety,which is not conducive to the subsequent catalytic treatment.Amorphous alloy catalysts have the characteristics of simple preparation,high security and efficiency,environmental friendliness,high corrosion resistance and so on,showing excellent catalytic performance in the field of selective hydrogenation of unsaturated compounds.In this paper,new amorphous catalysts NiCuB/SiO₂,NiBP/SiO₂,and NiCuB/Cu-MOF are synthesized by exploring the simple preparation technology of supported nano amorphous alloy catalysts.In addition,the process conditions and reaction kinetics of hydrogenation of aromatic ketone to aromatic alcohol are explored.Amorphous NiCuB/SiO₂ catalyst is established by chemical deposition supported method.Acetophenone hydrogenation is used as a probe reaction to optimize catalyst preparation conditions and investigate the hydrogenation performance of aromatic ketone.The results of SEM and N₂ adsorption-desorption characterization reveal that amorphous NiCuB/SiO₂ catalyst has highly dispersed active components and abundant pore structure.H₂-TPD indicates that the addition of Cu can effectively increase the amount of hydrogen adsorption sites,reduce the desorption difficulty of hydrogen adsorption,and is conducive to hydrogenation reaction.The results show that the amorphous NiCuB/SiO₂ catalyzed acetophenone is carried out in a high-pressure reactor.The acetophenone hydrogenation conversion is 99.4%and?-phenylethanol selectivity is about 97%at reaction conditions of 80?and 1.5 MPa H₂ pressure.The superior selectivity of carbonylation is closely related to the valence of reduced Cu in the catalyst;continuous hydrogenation in a fixed-bed reactor for 220 h,the activity of amorphous NiCuB/SiO₂ is stable and the conversion of acetophenone is more than 95%.NiBP/SiO₂ catalyst is synthesized by a two-step chemical reduction loading method for selective hydrogenation of acetophenone.The acetophenone hydrogenation conversion is ca.99%and the?-phenylethanol selectivity reaches up to 94%,which is approximately 1.4-fold higher than NiB/SiO₂?ca.69%?,thereby directly proving the unique inhibition on acetophenone over hydrogenation of P in the Ni-B catalytic system.The morphology,crystal form,atomic valence,specific surface area and other physical properties of the amorphous alloy are characterized by means of SEM,XRD,XPS,and N₂ adsorption-desorption.XPS shows that doped P in NiBP/SiO₂ is conducive to enhance the oxidation resistance and maintains valence stability of Ni and B.Furthermore,based on the Langmuir-Hinshelwood mechanism,a kinetic equation for the hydrogenation of aromatic ketones is derived.The reaction is negative order for aromatic ketones and first order for hydrogen.The activation energy of NiBP/SiO₂ to catalyze acetophenone hydrogenation to?-phenethyl alcohol is confirmed to be 50.73KJ/mol,and the chemical reaction rate constant is 7.1*104*exp?-50729.36/RT?.A new amorphous catalyst NiCuB/Cu-MOF is prepared by chemical deposition method with Cu-MOF as the support.It shows outstanding catalytic performance in the selective hydrogenation of aromatic ketones,the yields of?-phenylethanol are all greaterthan 97.4%.The amorphous NiCuB/Cu-MOF catalyst is recycled 16 times,and the selectivity of?-phenylethanol is always more than 99%.The application of the amorphous NiCuB/Cu-MOF is extended to catalyze the hydrogenation of various aromatic ketones such as p-methyl acetophenone and 4-isobutyl acetophenone.The catalyst shows great hydrogenation activity and superior applicability for several aromatic ketones.