Study On The Catalytic Performance Of Ni/ZrO₂ Catalysts For Liquid Phase Hydrogenation Of Maleic Anhydride With ZrO₂ Prepared By Solvothermal Method

The formula of zirconia is ZrO₂,which is odorless and tasteless,difficult to dissolve in dilute sulfuric acid,hydrochloric acid and water.Its resistivity,melting point and refractive index are high,and thermal expansion coefficient is low.Meanwhile,Zr O₂ is resistant to corrosion,and exhibit good chemical stability.It is widely used in high temperature resistant materials,ceramic insulation materials,ceramic opacifiers,and catalytic fields.Especially,in the field of catalysis,compared to traditional support materials of SiO₂ and Al2O3,ZrO₂ exhibit good thermal stability,rich in surface hydroxyl,has both acid-base and redox properties.Simultaneously,as a p-type semiconductor,ZrO₂ is prone to produce oxygen holes.When it is used as a catalyst support,it can produce strong metal-support interaction by electron transformation.The catalyst with ZrO₂ as support can exhibits excellent catalytic performance.ZrO₂ is mainly composed of m-ZrO₂,t-ZrO₂ and c-ZrO₂.Their physical and chemical properties are different.The crystalline of ZrO₂ has an important effect on the catalytic performance of ZrO₂ the catalyst and ZrO₂ supported catalyst.Moreover,it has been shown that the crystallite size of ZrO₂ also has an important effect on the catalytic performance of ZrO₂ supported catalyst.When the crystalline size of ZrO₂ is basically the same as that of the active component,the metal-support interface formed in the catalyst is obviously increased,the catalyst exhibits excellent catalytic performance.In addition,it is suggested that the effect of strong interaction between metal and support on the catalytic performance is greater than that of ZrO₂ crystal and ZrO₂ crystalline size.In order to understand the relationship between the metal-support interaction with the ZrO₂ crystal and ZrO₂ crystalline size,and its effect on the catalytic performance of ZrO₂ supported catalyst.A series of ZrO₂ with different properties were prepared by using methanol and water as solvent respectively.The catalytic performance of Ni/ZrO₂ catalysts for hydrogenation performance of maleic anhydride was studied.The main results and conclusions are as follows:1.Two t-ZrO₂ supports with the same crystalline size were prepared by using water and methanol as solvent respectively.Ni/Zr O₂ catalysts with Ni loading of 10 wt% wereprepared by impregnation method.The catalytic performances of catalysts for liquid phase hydrogenation of maleic anhydride were studied.The results showed that although the specific surface area of ZrO₂ prepared by using methanol as solvent was obviously smaller than that prepared by using water as solvent,the Ni/Zr O₂-M catalyst exhibited stronger metal-support interaction,the higher active metal dispersion and C=O hydrogenation activity.The selectivity of GBL was significantly higher than that of Ni/ZrO₂-W catalyst.2.A series of tetragonal ZrO₂ supports with different crystalline size were prepared by methanol thermal method.It was found that the crystalline size of ZrO₂ and Ni crystalline size decreased with the prolongation of methanol thermal time.The amount of Ni species that interact strongly with the support increases first and then decrease.When the methanol thermal time was 2 h,the catalyst had the most Ni species which interact strongly with support,showed the highest catalytic activity for C=O hydrogenation andg-butyrolactone.3.The ZrO₂ supports with different crystal form and crystal composition were prepared by changing the hydrothermal time.The catalytic performances of ZrO₂ supported Ni catalysts for the hydrogenation of maleic anhydride was also studied.The results showed that the Zr O₂ crystal form was gradually changed from tetragonal phase to monoclinic phase with the prolongation of hydrothermal time.The amount of Ni species that interact strongly with the support first increased and then decreased.When the hydrothermal time was 5 h,the catalyst had the most amount of Ni species that interact strongly with the support and showed the highest catalytic activity for C=O hydrogenation...