Ultrasonic-assisted Chemical Reduction Preparation Of New Amorphous Alloy Catalysts Used In Acetonitrile Selective Hydrogenation Reaction

Acetonitrile (CH₃CN) is one of the main byproducts during the industrialproduction of acrylonitrile. Hydrogenation of nitriles is an important route forutilization of nitriles. The common catalyst used in industrial hydrogenation ofCH₃CN is Raney Ni, but its selectivity for MEA is lower than 40%. Amorphous alloycatalysts represent a new class materials with short-range ordering while long-rangedisordering structure which may provide pathways to design excellent catalysts withhigh catalytic activity, better selectivity, and stronger resistance to the sulfur andamine poison. Besides, less or even no environmental pollution occurred during thecatalyst preparation and its application in catalysis. Much attention has been paid forthese amorphous alloy catalysts, owing to its potential in the atomic reactions andgreen chemistry.In the present thesis, ultrafine Ni-P , Ni-B, Co-B and supported Ni (Co)-B/SiO₂amorphous alloys were prepared with or without the help of ultrasonic wave. Theircatalytic performances were evaluated with liquid phase hydrogenation of acetonitrileto ethylamine. XRD, BET, SEM, TEM, H₂-chemisorption, H₂-TPD, XPS and ICP etcas well as reaction kinetic studies were employed to characterize these catalysts. Theeffect of ultrasound on their structural and electronic characteristics, as well as thecatalytic performances, including activity, selectivity and thermal stability wereinvestigated and discussed briefly.I. Catalyst preparation.(1) Preparation of Ni-P amorphous alloy: By adding NaH₂PO₂ into a solution containing (CH₃COO)₂Ni and CH3COONa, then the mixed solution was treated with a ultrasonic microniser at frequency of 20 kHz for some time with different intensity of 25, 50, 75 and 100 w/cm², respectively, and finally amorphous alloy Ni-P was obtained.(2) Preparation of black Ni(Co)-B amorphous alloy was the similar to Ni-P except that aqueous ammonia was first added into Ni(Co)Cl₂ solution to...