摘要
考察了共沉淀法制备的15．9％Pd／ZnO催化剂的还原对甲醇水蒸气重整制氢反应的影响．结果显示，当催化剂的还原温度为523～573K时，523K下反应的甲醇转化率达到了41．6％，CO2选择性为94．6％，出口CO浓度为1．26％．X射线衍射结果显示，当催化剂的还原温度为523K时PdZn合金开始形成．还原温度为523～573K范围内催化剂活性的提高归因于5～14nmPdZn合金粒子的存在．用程序升温还原及X射线衍射表征手段探究了还原过程中Pd与ZnO之间的相互作用．结果表明，Pd／ZnO可能经历了PdO／ZnO→Pd／ZnC→PdznO1-x／Zno→pdZn合金／ZnO的还原过程，而部分PdZn合金在反应过程中可重新被氧化成PdZnO1-x.对反应的活性物种进行了初步探讨．
The effect of reduction temperature of the coprecipitated 15.9 % Pd/ZnO catalyst on the catalytic activity for steam reforming of methanol was investigated. The results showed that methanol conversion at 523 K reached a maximum of 41.6% with a CO2 selectivity of 94.6% and an outlet CO concentration of 1.26% over the catalyst reduced at 523-573 K. X-ray diffraction analysis revealed that a PdZn alloy began to form at a reduction temperature of 523 K. The improvement in activity at reduction temperature ranging from 523 to 573 K was attributed to the formation of the PdZn alloy with crystal size of 5-14 nm. The interaction between Pd and ZnO upon reduction was also explored by means of temperature-programmed reduction and X-ray diffraction. The results demonstrated that the reduction over Pd/ZnO might undergo a process PdO/ZnO→Pd/ZnO→ PdZnOl-x/ZnO→PdZn alloy/ZnO. The PdZn alloy was found to be partially oxidized to PdZnOl-x again during the reaction. The PdZn alloy and PdZnOl-x species might be the real active species.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第3期234-238,共5页
关键词
钯
氧化锌
负载型催化剂
甲醇水蒸气重整
钯锌合金
活性物种
还原
palldium
zinc oxide
supported catalyst
steam reforming of methanol
PdZn alloy
actiye species reduction
作者简介
王艳华，女，1973年生，博士．
