改性Ni/La_2O_3催化剂抑制甘油蒸汽重整制氢中的甲烷化反应

Modified Ni/La2O3Catalyst Inhibiting Methanation Reaction of Glycerol Steam Reforming for Hydrogen Production

为抑制Ni/La_2O_3催化剂在丙三醇重整反应中的甲烷化反应,提高氢气选择性,制备了Ni-M/La_2O_3改性催化剂(M为Mg、Al、Cu、Ca、K、Na等金属),并在固定床反应器中进行催化剂活性评价。结果表明,在催化剂中以氢氧化物形式存在金属助剂(Ca、K、Na)对于甲烷化反应的抑制要优于以氧化物形式存在的(Mg、Al、Cu)。碱性环境下,载体金属镧主要以La(OH)_3和La CO_3OH的形式存在,抑制了La_2O_2CO_3和La_2Ni O_4的生成,从而降低了其对甲烷化反应的催化活性。XRD检测说明了关于抑制甲烷化反应的机理,即Na助剂的添加抑制了La_2Ni O_4的产生,降低了甲烷化反应的选择性。

We reported the modified catalyst Ni-M/La_2O_3, where M was the modifying agent(Mg, Al, Cu, Ca, K, and Na) for improving the selectivity of hydrogen and inhibiting the methanation reaction of glycerin steam reforming, and made evaluation of catalyst activity in the fixed bed reactor. The results indicated that the modifying agent(Ca, K, Na) and(Mg, Al, Cu) were presented by hydroxides and oxides respectively. The inhibition of the former was superior to the latter in methanation reaction. In alkaline environment, the carrier metal lanthanum were primarily presented by La(OH)_3and La CO_3 OH, restraining the generation of La_2O_2CO_3 and La_2Ni O_4 and which reduced the catalytic activity of methanation reaction. The X-ray diffraction(XRD) analysis of the catalystilluminates the mechanism of i nhibiting methanation reaction, namely the addition of Na inhibits the generation of La_2 Ni O_4and reduced the selectivity of methanation reaction.