Ni-MCM-41的水热合成与稳定性

以硅酸钠(Na2SiO39H2O)、氯化镍(NiCl2·6H2O)等无机盐为原料,通过水热法合成含有不同镍含量的介孔分子筛(nickel-containing meso-porousmoleeular sieve,Ni-MCM-41).采用X射线粉末衍射、等离子发射光谱、程序升温还原,透射电子显微镜和N2吸附-脱附等技术对焙烧后的样品的物化性能进行表征,同时对所合成Ni-MCM-41的水热稳定性进行研究.结果表明:在水热条件下成功合成出4种不同镍含量的Ni-MCM-41,其比表面积在495.9～888.2 m2/g之间,平均孔径在2.43～2.92 nm之间.随着介孔分子筛中金属镍含量的增加,Ni-MCM-41的比表面积、孔体积变小和介孔有序性变差.原料摩尔比n(SiO2):n(NiO)1:0.05时,合成的Ni-MCM-41的介孔有序性最好.所合成的含Ni-MCM-41经750℃焙烧3h后仍然具有介孔结构;另一方面,经100℃水热处理5d后的样品也具有介孔结构,但介孔有序性差.

HYDROTHERMAL SYNTHESIS AND STABILITY OF Ni-MCM-41

Nickel-containing meso-porous molecular sieves (Ni-MCM-41) with different nickel contents were synthesized by the hydrothermal method using sodium silicate and nickel chloride as raw materials. The physicochemical properties of the calcined samples were characterized by X-ray diffraction (XRD), inductive coupled plasma (ICP) technique, temperature programmed reduction (TPR), transmission electron microscope (TEM), and N2 physical adsorption, and the thermal and hydrothermal stabilities of the syn-thesized Ni-MCM-41 samples were also investigated. The experimental results show that Ni-MCM-41 with different nickel contents are successfully synthesized under hydrothermal conditions, and have specific surface areas in the range of 495.9-888.2 m2/g and average pore sizes in the range of 2.43-2.92 nm. The specific surface area and pore volume of the synthesized Ni-MCM-41 decreases with the increase of the amount of nickel doping and the meso-porous ordering becomes poor. Also, when the molar ratio of SiO2 and NiO in the starting material is 1:0.05, the ordering of the synthesized Ni-MCM-41 is the best among the four doping contents. The results of thermal and hydrothermal tests show that after calcination at 750℃(2 for 3 h, the Ni-MCM-41 still retains its mesostracture.On the other hand, the framework of the Ni-MCM-41 is still retained after hydrothermal treatment at 100 "C for 5 d, but the meso-porous ordering is poor.