气溶胶辅助合成介孔Ni/SiO_(2)中空微球及其催化对硝基苯酚还原性能研究

Aerosol assisted synthesis of mesoporous Ni/SiO_(2)hollow microspheres and their catalytic properties for p-nitrophenol reduction

通过催化还原反应将工业废水中常见污染物对硝基苯酚还原为具有较高附加值的对氨基苯酚,对于发展绿色化学与化工具有重要意义。虽然贵金属催化剂(Au、Pd等)在该反应中表现出优异的催化性能,但较高的成本限制了其工业应用。相比而言,Ni基催化剂因具有成本低、活性高等优势受到了广泛关注,但传统的合成方法通常存在Ni纳米颗粒尺寸较大、易团聚等缺点。首先,以气溶胶技术联合表面活性剂十六烷基三甲基溴化铵(CTAB)利用溶剂蒸发自组装策略合成了SiO_(2)-MHMs载体,然后采用硝酸镍为Ni源,利用浸渍以及NaBH_(4)还原策略得到了一系列不同Ni负载量(质量分数)的Ni/SiO_(2)-MHMs催化剂。X-射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、N_(2)物理吸/脱附等多种表征手段的分析结果表明,SiO_(2)-MHMs载体具有丰富的有序介孔结构,且为中空凹陷的微球形貌,Brunanuer-Emmett-Teller(BET)比表面积和总孔孔容分别为1421 m^(2)/g和0.92 cm^(3)/g。在载体经过浸渍-还原后得到的5-Ni/SiO_(2)-MHMs催化剂中,Ni纳米粒子高度分散于载体表面和介孔孔道内,导致其BET比表面积(854 m^(2)/g)和总孔孔容(0.47 cm^(3)/g)均减小。将所得催化剂应用于对硝基苯酚还原反应,结果表明当Ni负载量为5%时制得的催化剂表现出最佳催化性能(4 min内完全转化),且循环4次后催化性能没有明显下降,优于其他已报道的Ni基负载型催化剂。

The catalytic reduction of p-nitrophenol,a common pollutant in industrial wastewater,to p-aminophenol with higher added value is of great significance for the development of green chemistry and chemical industry.Although noble metal catalysts(Au,Pd,etc.)show excellent catalytic performance for this reaction,high cost limits their industrial application.In contrast,Ni-based catalysts have attracted wide attention due to their advantages of low cost and high activity but traditional synthesis methods usually have disadvantages such as large size of Ni nanoparticles and easy agglomeration.Firstly,the SiO_(2)-MHMs support was synthesized by aerosol technology combined with surfactant cetyltrimethyl ammonium bromide(CTAB)using solvent evaporation self-assembly strategy.And then using nickel nitrate as Ni source,a series of Ni/SiO_(2)-MHMs catalysts with different Ni loadings(mass fraction)were obtained by using impregnation and NaBH_(4) reduction strategy.The analysis results of X-ray diffraction(XRD),scanning electron microscope(SEM),fourier transform spectroscopy(FT-IR)and N_(2) physical adsorption/desorption and other characterization methods show that the SiO_(2)-MHMs support has abundant ordered mesopore structure with concave hollow microsphere morphology,and Brunanuer-Emmett-Teller(BET)specific surface area and total pore volume are 1421 m^(2)/g and 0.92 cm^(3)/g,respectively.In the 5-Ni/SiO_(2)-MHMs catalyst obtained by impregnation-reduction of the support,Ni nanoparticles are highly dispersed on the surface of the support and in the mesoporous channels,resulting in a decrease in the BET specific surface area(854 m^(2)/g)and total pore volume(0.47 cm^(3)/g).The obtained catalyst was applied to the reduction reaction of p-nitrophenol.The results show that the catalyst with 5%Ni loading shows the best catalytic performance(complete conversion within 4 min),and the catalytic performance does not decrease significantly after 4 cycles,which is better than other reported Ni-based supported catalysts.