The Preparation Of Ni-P Amorphous Alloy/Modified Bentonite Catalyst And Its Catalytic Hydrogenation Performance

Amorphous alloy catalyst has the advantages of high catalytic activity and good anti-toxicity,so it is widely used in catalytic hydrogenation reaction.Bentonite is a superior mineral resources in Guangxi,but most of them are about primary products,the preparation of supported amorphous alloy catalyst with bentonite as carrier is beneficial to further broaden the application field of Ningming bentonite in Guangxi.Ni-P amorphous alloy/modified bentonite catalyst was prepared used modified bentonite as a carrier supported Ni-P amorphous alloy with a bentonite from Guangxi Ningming as the raw material,and characterized by XRD,H2-TPR,H2-TPD,N2 adsorption desorption etc,and the catalytic hydrogenation property of the catalyst were studied using nitrobenzene hydrogenation to synthesis aniline as a probe reaction.The main contents of the paper are as follows:Firstly,for the purpose of screening the appropriate carrier,the bentonite was modified by calcination,acid treated and Al pillared,and the modified bentonite was used to support Ni-P amorphous alloy.Effect of different modification methods of bentonite on the catalytic activity of nitrobenzene hydrogenation with Ni-P amorphous alloy/modified bentonite.Three kinds of modified bentonite and the corresponding Ni-P amorphous alloy/modified bentonite catalyst were characterized by XRD,H2-TPD and N2 adsorption and desorption.The results showed that,compared with Ni-P amorphous alloy/raw bentonite,the acid treated bentonite and A1 pillared bentonite supported Ni-P amorphous alloy significantly increased the specific surface area of the Ni-P amorphous alloy/modified bentonite catalyst,and increased in the number of Ni active sites,and the catalytic activity of nitrobenzene hydrogenation to aniline was improved.Reaction carried out at 110 ?,with hydrogen pressure at 1.4 MPa for 5 h,providing 49.1%nitrobenzene conversion and 98.9%aniline selectivity over Ni-P/acid treared bentonite catalyst,and nitrobenzene conversion and aniline selectivity over Ni-P amorphous alloy/Al pillared bentonite catalyst were 55.8%and 98.7%,respectively,while nitrobenzene conversion and aniline selectivity over Ni-P amorphous alloy/bentonite catalyst were only 21.8%and 97.3%,respectively.Secondly,in order to improve the stability of Ni-P/modified bentonite catalysts,Ni-P amorphous alloy/acid-treated bentonite catalyst was prepared by microwave drying assisted chemical reduction method using acid-treated bentonite as the carrier,the effects of process conditions on the activity of the microwave drying of Ni-P amorphous alloy/acid-treated bentonite were investigated such as Ni contents,P/Ni molar ratio,catalyst precursor pH,microwave power,catalyst precursor calcination temperature,and reaction temperature,H2 pressure,reaction time.The Ni-P amorphous alloy/acid treated bentonite catalysts dried by a traditional drying methods and microwave-assisted drying methods were characterized by XRD,SEM,XPS,H2-TPR and H2-TPD.The results showed that the microwave drying promoted the dispersion of Ni active components on the surface of the acid treated bentonite,reduced the size of Ni-P alloy particles,and enhance the interaction between Ni and support.when Ni amount was 20 wt%,P/Ni molar ratio was 4,the pH of catalyst precursor is 11,the microwave power was 250 W,catalyst precursor calcination temperature is 200 ?,and reaction carried out at 110 ?,with hydrogen pressure at 1.8 MPa for 5 h,nitrobenzene conversion and aniline selectivity of the Ni-P amorphous alloy/acid treated bentonite catalyst dried by a traditional drying method were 50.2%and 98.5%respectively,and the inactivation seriously was started after four times used,while Ni-P amorphous alloy/acid treated bentonite catalyst drying by microwave heating remained essentially unchanged after 6 times used,in which nitrobenzene conversion was always more than 96.0%and aniline selectivity was about 98.5%.The results indicated that the microwave drying make Ni-P amorphous alloy/acid treated bentonite catalytic activity significantly improved,the stability had a slight improvement.Thirdly,in order to further improve the activity and stability of Ni-P/acid treated bentonite catalyst,Ni-Ba-P/acid treated bentonite catalyst was prepared by introducing Ba into Ni-P/acid treated bentonite.The effect of Ba addition on the activity of Ni-P amorphous alloy/acid treated bentonite was studied.The results showed that the addition of Ba obviously improved the dispersion of Ni on the carrier,and increased the number of Ni active sites,which made the catalytic activity of the catalyst improved obviously.The Ni-Ba-P amorphous alloy/acid treated bentonite catalyst with a molar content of 3%showed the best catalytic activity,under the condition of 105 ?,hydrogen pressure 1.4 MPa,reaction time 3 h,nitrobenzene conversion reached 99.0%and aniline selectivity was about 98.9%.Compared with Ni-P amorphous alloy/acid treated bentonite catalyst,The recycle number of Ni-P/acid-treated bentonite catalyst with 3%molar content increased from 6 to 10,indicated the stability was enhanced.