The Highly Selective Hydrogenation Of Methyl Isobutyl Ketone With Nickel Based Catalysts

Methyl isobutyl carbinol is an important industrial raw material,and the production process is the byproducts of 4-methyl-3-pentene-2-one hydrogenation in the synthesis of methyl isobutyl ketone under certain conditions.The disavantange of the reaction is the complicated process and the difficult separation of products.Therefore,it is necessary to develop methyl isobutyl ketone as raw material to prepare methyl isobutyl carbinol by direct catalytic hydrogenation.The purpose of this paper is to synthesis the supported Raney nickel catalyst and the supported NiO/?-Al₂O₃ catalyst which are used in methyl isobutyl ketone hydrogenation reaction and studied on preparation conditions of catalyst.The surface structure,crystal type and material composition are analyzed in detail using N₂ physisorption,XRD,SEM,XPS,TG-DTA and reduction by hydrogen?TPR?.The preparation process of two kinds catalyst is optimized.Hydrogenation reaction conditions for the synthesis of methyl isobutyl carbinol are investigated with two kinds of catalysts,and the main results are listed as follows.Firstly,characterization results of supported Raney nickel catalyst shows that the catalyst contains three phases:Al₃Ni₂,Ni,?-Al₂O₃,in which Al₃Ni₂ and Ni are the main source of active components and the presence of?-Al₂O₃ is helpful to improve the stability of the catalyst.Conversion of MIBK can reach over 99.1%and selectivity of MIBC is more than 99.9%under the following conditions:170?of reaction temperature,4 MPa of the reaction pressure,0.8h^-1 of liquid volumetric space velocity and 400:1 of V?H₂?/V?oil?.Secondly,NiO/?-Al₂O₃catalysts were prepared by impregnation method and the effect of the nickel source,loading,calcination times and calcination temperature on the catalytic activity were investigated.Meanwhile,the catalysts were analyzed by various characterization methods.The experimental results show that NiO/?-Al₂O₃ present higher catalytic performance under the prepared condtions with the nickel nitrate as the nickel source,loading of NiO was 20%,calcination at 440?for 5 h.In addition,the catalyst shows the largest specific surface area,the best crystal structure,the highest active component content,the small particle,and uniform distribution of NiO on the surface of the carrier.Finally,the NiO/?-Al₂O₃ is used to hydrogenation reation of MIBK.The effects of and reduction temperature,reduction times,reaction temperature,pressure,hydrogen ketone ratio and liquid space velocity on the reaction performance was studied.When the reduction temperature is320?,the reduction time is 4 h,the reaction temperature is 170?,the reaction pressure is 5.0 MPa,the hydrogen ketone ratio is 500,the liquid space velocity is 0.75h^-1,the reaction conversion rate can reach 98.8%and the selectivity of MIBC reached more than 99%.The Catalytic life of NiO/?-Al₂O₃ catalyst was investigated under the optimum conditions.When the reaction was carried out after 480 h,the hydrogenation ability of the catalyst was weakened,and the decrease of its activity may be related to the formation of carbon,sintering,and loss of the active components of the catalyst after long period.