花球状镁铝复合氧化物负载Ni?Co催化剂的合成及正十二烷水蒸气重整制氢

采用水热晶化的方法制备了花球状镁铝层状水滑石材料,经过高温焙烧和氢气还原成功制备了镁铝复合氧化物负载的Ni?Co合金催化剂。通过扫描电子显微镜、透射电子显微镜、氮气吸附-脱附测试、粉末X射线衍射、程序升温还原等技术表征了所制备催化剂的物理化学性质,并且测试了所制备催化剂催化正十二烷水蒸气重整制氢性能。实验结果表明:水热晶化后催化剂的前驱体是花球状层状水滑石结构,焙烧后催化剂以复合氧化物的结构存在,且存在非常丰富的介孔和大孔。通过调控Co的加入量,可以调控金属载体相互作用的强度及金属颗粒尺寸。还原后,Ni和Co形成合金且均匀地分布在层状薄片镁铝复合氧化物上面。所制备的催化剂用于正十二烷水蒸气重整制氢,结果显示,相比于Ni单金属催化剂,形成Ni?Co合金的催化剂的活性及产氢率均有较大程度的提升,且抗积碳性能大幅度提高。这归因于Ni?Co协同的合金状态和较小的金属纳米颗粒尺寸。

Synthesis of Ni-Co Catalysts Supported on Flower-like MgAl Composite Oxide for Hydrogen Production by n-Dodecane Steam Reforming

Flower-like Ni-Co-Mg-Al layered hydrotalcite materials were prepared by a hydrothermal crystallization method. After high-temperature calcination and hydrogen reduction, a series of Ni-Co alloy catalysts supported on MgAl composite oxides were successfully prepared. The physicochemical properties of the catalysts were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption test, powder X-ray diffraction and temperature programmed reduction. The catalysts were tested for hydrogen production from steam reforming of n-dodecane. The results show that the precursor of hydrothermal crystallization catalyst was spherical flower-like layered hydrotalcite structure, and the as-calcined catalyst was in the form of composite oxide with abundant mesopores and macropores. The metal-support interaction and particles size of metal can be controlled by adjusting the amount of Co added. After reduction, Ni and Co formed an alloy and distributed uniformly on the lamellar MgAl composite oxide. Compared with the catalyst of single-metal Ni, the activity and hydrogen production rate of Ni-Co alloy catalyst were greatly improved, and the coke resistance was greatly improved. This is due to the synergistic effects of Ni-Co alloy and small metal nanoparticles.