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乙烷在钛酸盐复合氧化物上的氧化脱氢Ⅰ.锂掺杂对催化性能的影响
OXIDATIVE DEHYDROGENATION OF ETHANE OVER PEROVSKITE CATALYSTS Ⅰ. Effect of Li Doping on Catalytic Behavior
【摘要】 研究了掺杂钛酸盐催化剂用于乙烷氧化脱氢(ODHE)的催化行为,发现适量的Li+取代Ti4+后可明显改善催化剂对乙烯的选择性.催化剂CaTi0.9Li0.1O3-δ在850℃时乙烷转化率和乙烯选择性分别为87.8%和71.7%,乙烯的单程收率为63.0%;催化剂Sr0.9Ca0.1Ti0.9Li0.1O3-δ可在极宽的温度范围(700~850℃)内保持很高的乙烯选择性(≥90%).O2-TPD-MS和H2-TPR实验结果表明,Li+取代Ti4+后在催化剂晶格中产生非完全还原的氧(Oδ-),该氧物种是ODHE反应的活性氧种,直接与催化剂的乙烯选择性相关.ODHE反应机理与甲烷氧化机理具有某些相似性.反应条件考察结果表明,低空速有利于乙烷的低温转化,高空速可抑制气相中非催化反应的进行,有利于乙烯的选择性,尤其是高温下乙烯的选择性.
【Abstract】 The oxidative dehydrogenation of ethane (ODHE) over various Li doped MTiO 3 (M=Ca, Sr) catalysts has been examined in the temperature range of 700-850℃. 87 8% for C 2H 6 conversion, 71 7% for C 2H 4 selectivity and 63 0% for C 2H 4 yield can be obtained over catalyst CaTi 0.9 Li 0.1 O 3- δ at 850℃. The substitution of Sr for Ca in CaTi 0.9 Li 0.1 O 3- δ can maintain a high selectivity (≥90%) for C 2H 4 in a very wide range (700 ̄850℃). A much better improvement in C 2H 4 selectivity can be observed by substituting of Li + for Ti 4+ in MTiO 3. By means of O 2 TPD MS and H 2 TPR, the effect of Li + doping can be explained by the increment of oxygen vacancy and non fully reduced oxygen species. In the reactor employed in this study, the homogeneous reactions are inhibited by increasing the space velocity.
- 【文献出处】 催化学报 ,CHINESE JOURNAL OF CATALYSIS , 编辑部邮箱 ,1997年02期
- 【分类号】O643.38
- 【被引频次】28
- 【下载频次】126