镁铝混合氧化物负载镍催化剂上液化石油气的预重整

Pre-reforming of Liquefied Petroleum Gas over Magnesium Aluminum Mixed Oxide Supported Nickel Catalysts

采用共沉淀-浸渍法并在较低温度(400～700°C)下焙烧制备了镁铝混合氧化物(MgmAl)负载的Ni催化剂.X射线衍射和程序升温还原结果表明,Ni物种高度分散于催化剂表面,没有形成尖晶石NiAl2O4.在650°C可被还原成金属Ni纳米晶粒,在400°C和较低水/碳摩尔比(S/C=2)条件下表现出较好的催化液化石油气(LPG)重整反应性能.详细考察了Mg/Al摩尔比、Ni负载量、载体和催化剂的焙烧温度对催化剂活性和稳定性的影响.结果表明,由500°C焙烧的Mg1.25Al载体负载的15%Ni催化剂,并于500°C焙烧时,在LPG重整反应中表现出最优的性能,尽管它比高温(≥800°C)焙烧制备的Ni/MgmAl催化剂更易积炭,催化活性和稳定性有所下降,但由于还原温度较低,在交通和小规模供电的燃料电池领域更具实际应用意义.

The catalytic performance of Ni catalysts supported on magnesium aluminum mixed oxide （Ni/MgmAl） for the pre-reforming of liquefied petroleum gas （LPG） was studied, and the catalysts were prepared by the co-precipitation-impregnation method and calcined in the lower temperature range of 400–700 oC. The X-ray diffraction and H2 temperature-programmed reduction results showed that Ni species were highly dispersed on the catalyst surface without NiAl2O4 spinel formation. The Ni/MgmAl catalysts could be reduced to metallic Ni nanoparticles at 650 oC, which showed excellent catalytic activity and stability for LPG pre-reforming at 400 oC and a low steam/carbon molar ratio of 2.0. The effects of Mg/Al molar ratios, Ni loading, and calcination temperature of the support and catalyst on the catalytic behavior of the Ni/MgmAl catalysts were investigated in detail. The results revealed that the 15%Ni/Mg1.25Al catalyst with both support and catalyst calcined at 500 oC had the optimal catalytic performance for LPG pre-reforming. Compared with Ni/MgmAl catalysts calcined at high temperature （≥ 800 oC）, the present catalysts showed easier coke deposition and a slight decrease in catalytic activity and stability. However, it may be more promising candidate for LPG pre-reforming for the use of hydrogen fuel cells in transportation and small stationary application due to lower reduction temperature.