1,2-环己二醇脱氢镍基催化剂制备方法

以硝酸镍为镍源,分别以NH3.H2O,NH4HCO3,NH3.H2O+NH4HCO3为沉淀剂采用沉淀法制备镍/硅藻土催化剂,用于1,2-环己二醇脱氢制备邻苯二酚,考察了不同沉淀剂、焙烧温度、沉淀温度制备的催化剂对1,2-环己二醇脱氢反应性能的影响,并通过XRD,BET,CO2-TPD(热设计功耗)等方法对催化剂进行了表征。结果表明:不同的沉淀剂对镍的分散度、孔结构及表面碱量都有影响,以NH3.H2O+NH4HCO3复合沉淀剂制备的镍/硅藻土催化剂上活性组分镍晶粒度小、分散度较高,催化剂平均孔径较大,催化剂表面碱中心数目多、碱量大,表现出良好的催化活性和邻苯二酚选择性。另外,催化剂适宜沉淀温度为90℃、焙烧温度为350℃。上述适宜条件制备的催化剂在320℃下用于1,2-环己二醇脱氢制备邻苯二酚,1,2-环己二醇转化率达到99.1%,邻苯二酚选择性达到86.8%。

Preparation method of Ni-based catalysts for dehydrogenation of 1, 2-cyclohexanediol

The supported nickel/ kieselguhr catalysts were prepared by precipitation method with nickel nitrate as raw material and NH3·H2O,NH4HCO3,NH3·H2O+NH4HCO3 as precipitants.The catalytic performance of the catalysts for dehydrogenation of 1,2-cyclohexanediol to catechol was evaluated in a fixed-bed reactor.In addition,the effects of nickel/kieselguhr catalysts were studied under the conditions of different precipitants,calcination temperatures and depositing temperatures in the experiments.The optimal preparation conditions were that calcination temperature is 350 ℃ and depositing temperature is 90 ℃.The supported nickel catalysts were characterized by means of XRD,BET and CO2-TPD.The results show that the different precipitants have significant effect on particle dispersion,pore structure and surface base content of nickel.The active nickel species disperse well in the nickel catalysts supported on kieselguhr(NH3·H2O+NH4HCO3 as precipitant) and these catalysts with large pore and more base content exhibit higher activity and selectivity for catechol.The conversion of 1,2-cyclohexanediol and selectivity of catechol can reach 99.1% and 86.8% respectively under the conditions of 320 ℃.