还原方式及还原温度对甲烷部分氧化镍催化剂结构和反应性能的影响  

Effect of reduction method and temperature on structure and performance of nickel-based catalysts for partial oxidation of methane

作　　者：宫立倩[1] 陈吉祥[2] 李正[1] 张继炎[2] 刘季[1] 

机构地区：[1]中国石油吉林石化公司研究院,吉林吉林132021 [2]天津大学化工学院催化科学与工程系,天津300072

出　　处：《燃料化学学报》2008年第2期192-196,共5页Journal of Fuel Chemistry and Technology

摘　　要：采用H2-TPR、TEM及活性评价等手段,考察了还原方式(等温和程序升温还原)及还原温度对不同温度(550℃和950℃)焙烧制备的镍基催化剂结构和甲烷部分氧化反应性能的影响。结果表明,与程序升温还原方式相比,等温还原的催化剂中镍物种的还原度较低、Ni晶粒度较小。还原方式对550℃焙烧制备的催化剂(POM-1)的甲烷部分氧化反应性能影响不明显,但等温还原的催化剂反应过程中床层温度较低。随着等温还原温度的提高,POM-1催化剂的镍还原度有所降低,而950℃焙烧制备的催化剂(POM-5)还原度略有增加,且具有较小的镍晶粒。随着等温还原温度的提高,POM-1催化剂反应性能无明显差异,但床层热点温度提高;POM-5催化剂反应性能随还原温度的提高而提高,且床层温度呈现降低趋势。通过分析发现,催化剂床层温度与催化剂镍晶粒大小密切相关,较小的镍晶粒利于床层热点温度的降低,这与较大镍晶粒利于甲烷完全氧化反应有关。Influence of reduction method （ temperature-programmed reduction （TPR） and isothermal reduction） and reduction temperature on the structure and performance of nickel-based catalysts for methane partial oxidation was investigated by means of H2-TPR, TEM and catalytic tests. Two catalysts were first prepared at different calcination temperatures （POM-1, calcined at 550 ℃ ; POM-5, calcined at 950 ℃ ）. For POM-1 catalyst, the isothermal reduction led to lower reduction degree and smaller nickel crystallites compared with TPR. However, the catalysts with different reduction methods had little difference in the catalytic activity. With increasing isothermal reduction temperature, the reduction degree of POM-1 catalyst decreased, and that of POM-5 catalyst increased slightly. The size of nickel crystallites was smaller in POM-5 catalyst than that in POM-1 catalyst. With increasing isothermal reduction temperature, there was no marked effect on the reactivity of POM-1, while the hotspot of POM-1 catalyst bed increased. However, the reactivity of POM-5 catalyst increased and the hotspot of POM-5 catalyst bed decreased, with increasing the reduction temperature. The hotspot of catalyst bed was related to the size of nickel crystallites. The larger the size of nickel crystallites was, the higher the hotspot temperature of the catalyst bed; this was perhaps due to the complete oxidation of methane promoted by large nickel crystallites.

关 键 词：NI基催化剂 还原方法 甲烷 部分氧化 合成气 

分 类 号：TQ032.41[化学工程]