摘要
本文研究了不同载体γ-Al_2O_3、ZrO_2、CeO_2和La_2O_3上硫化的钼催化剂的甲烷化反应性能,得到甲烷化活性顺序:Mo/ZrO_2>Mo/γ-Al_2O_3>Mo/CoO_2>Mo/La_2O_3;热稳定性顺序:Mo/La_2O_3>Mo/CeO_2>Mo/γ-Al_2O_3>Mo/ZrO_2。研究了低温氧吸附的预处理条件,并用脉冲色谱法测定了载体,反应前和反应后催化剂的氧吸附量。结果表明反应后低温氧吸附量下降百分数和活性下降百分数有线性关系。讨论了以低温氧吸附与甲烷化活性进行关联的限制和活性中心的本质。
CO methanation on catalysts composed of molybdenum supported on γ-Al_2O_3,ZrO_2, CeO_2 and La_2O_3 was investigated. Under the conditions of H_2: CO = 3:1and space velocity 2400h^(-1), the temperature of the highest activity for metha-nation on those catalysts is different. The initial activity fo rmethanation de-creases in the following [sequence: Mo/ZrO_2>Mo/γ-Al_2O_3>Mo/CeO_2>Mo/La_2O_3·The stability in activity at 450℃ after reaction for 20h decreases in thereverse sequence: Mo/La_2O_3>Mo/CeO_2>Mo/γ-Al_2O_3>Mo/ZrO_2. The condi-tion of pretreatment for O_2 chemisorption on Mo/γ-Al_2O_3, Mo/ZrO_2 wasstudied. At -83.5℃, the O_2 adsorption on the supports, the fresh and the usedcatalysts were examined by pulse adsorption chromatography. The percentageof decreased O_2 uptake between fresh and used catalysts versus the percentageof loss in activity (after reaction for 10h at 450℃) has a linear correlation.Besides, the effect of supports for catalytic behaviour, the nature of the ac-tive sites and the restriction of characterizing activity by O_2 adsorption werediscussed.
基金
国家自然科学基金
关键词
钼催化剂
甲烷化反应
硫化
methanation of CO
supported molybdenum catalyst
oxggen chemisorption of Mo catalyst
