摘要
采用等体积浸渍法制备了V2 O5 SiO2 负载的Pd Cu双金属催化剂 ,以程序升温还原 /程序升温氧化、红外光谱、程序升温脱附和微反技术表征了Pd Cu/V2 O5 SiO2 对CO2 和丙烷的化学吸附性能及对CO2 部分氧化丙烷脱氢反应的催化性能 .结果表明 ,在催化剂表面金属活性位 (Pd ,Cu)和邻近的Vn + 协同下形成的CO2 卧式吸附态可在 172和 2 84℃断裂形成CO和晶格氧 ,以甲基氢和亚甲基氢双位吸附在V=O上的丙烷分子吸附态可在 2 38℃脱氢生成丙烯 .在 6 0 0℃ ,CO2 /C3 H8体积比为 1和空速为 12 86h-1的条件下 ,丙烷转化率为 35 2 2 % ,丙烯选择性为 85 4 4 % .催化剂V=O中的晶格氧参与了丙烷氧化脱氢过程 .
The Pd-Cu bimetallic catalyst supported on V 2O 5-SiO 2 was prepared by the incipient wetness impregnation method. Its chemisorption properties and catalytic behavior for C 3H 8 partial oxidation with CO 2 were characterized by temperature-programmed reduction, temperature-programmed oxidation, infrared spectroscopy (IR), temperature-programmed desorption (TPD), and microreactor techniques. The IR results show that three active sites, i.e., metal site M(Pd-Cu), Lewis acid site V n+, and Lewis base site V=O, are present on the surface of the Pd-Cu/V 2O 5-SiO 2 catalyst. Horizontally adsorbed CO 2 is formed on the metal sites and the adjacent V n+, and propane is adsorbed on lattice oxygen (V=O) through H atoms of methyl and methylene groups. The TPD results show that CO and lattice oxygen are formed by breaking of horizontally adsorbed CO 2 at 172 and 284 ℃, and propylene is formed by desorption of adsorbed propane at 238 ℃. Under the conditions of 600 ℃, 0.1 MPa, gas space velocity of 1*!286 h -1, and CO 2/C 3H 8 ratio of 1, the propane conversion of 35.22% and propylene selectivity of 85.44% are achieved. Lattice oxygen of V=O is involved in the reaction process. Based on the experimental results, a surface reaction mechanism of propane oxidation to propylene using carbon dioxide as the oxidant over Pd-Cu/V 2O 5-SiO 2 is proposed.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2004年第2期143-148,共6页
基金
国家重大基础研究前期研究专项资助项目 ( 2 0 0 1CCA0 3 60 0 )
关键词
二氧化碳
丙烷
氧化脱氢
丙烯
钯
铜
双金属催化剂
复合氧化物载体
脱氢
carbon dioxide, propane, oxidative dehydrogenation, propene, palladium, copper, bimetallic catalyst, composite oxide support
