【作者】 梅大江；

【导师】 龚茂初；

【作者基本信息】 四川大学 ， 物理化学， 2007， 硕士

【摘要】 本文考查了整体式Ni／Al₂O₃催化剂经中高温焙烧（300-800℃）后对于甲烷部分氧化反应的催化活性，并对催化剂进行了XRD，TPR表征。实验结果表明，在300-500℃范围内，随着焙烧温度的升高，活性组分同载体间相互作用的增强，这有助于提高活性组分的分散性，从而使得催化剂的活性随焙烧温度的升高而有所提高。但当焙烧温度在500-800℃范围时，焙烧温度的升高使得催化剂越来越难被还原，从而使得催化剂活性随着焙烧温度的升高而依次降低。故而500℃焙烧催化剂催化活性最佳。本文对Ni／Al₂O₃催化剂进行了超高温焙烧（1200-1400℃），考查了还原温度以及焙烧温度对催化剂催化活性的影响，并对催化剂进行了XRD表征。实验结果表明，催化剂经1200℃焙烧后，催化剂中的Ni物种基本上是以NiAl₂O₄形式存在，还原温度低于800℃，NiAl₂O₄不能被还原，催化剂活性很差，当还原温度达到800℃时，有部分NiAl₂O₄被还原为Ni⁰，催化剂具有较高活性，当还原温度为900℃，NiAl₂O₄完全被还原，故而催化剂活性最佳。当焙烧温度在1200-1400℃范围内，随着焙烧温度的升高，NiAl₂O₄晶粒逐渐增大，使得NiAl₂O₄越来越难被还原。故催化剂在900℃还原后，其催化活性随焙烧温度的升高而依次下降。同时发现在Ni／Al₂O₃催化剂中添加La助剂后，可以抑制1200℃焙烧过程中NiAl₂O₄晶粒的长大，从而有效提高了催化剂的催化活性。本文考查了Ni／CeO₂-ZrO₂-Al₂O₃系列催化剂的催化活性及抗积碳性能，并对催化剂进行了BET，XRD，TPR，XPS表征。实验结果表明，由于Ni／CeO₂-ZrO₂-Al₂O₃催化剂具有良好的Ni物种分散性以及大的比表面，从而对于甲烷部分氧化反应表现出良好的催化活性和抗积碳性能。随着Al含量的增加，催化剂中Ni物种同载体之间的相互作用逐渐增强，从而使得催化剂的抗积碳性能依次增强。更多还原

【Abstract】 The monolithic Ni/Al₂O₃ catalysts with the calcination temperature varied from300℃to 800℃were investigated for partial oxidation of methane to syngas and thecatalysts were charactered by XRD and TPR methods. The results show that whenthe calcination temperature is in the range of 300-500℃, the dispersion of the activesite increases with the increasing of the calcination temperature. The activity of thecatalysts enhances with the increasing of the calcination temperature. When thecalcination temperature in the range of 500-800℃, the reduction of the catalystbecomes harder and harder with the increasing of the calcination temperature. Theactivity of the catalysts decreases with the increase of the calcination temperature.The catalyst calcined at 500℃shows the best activity.The influence of the reduction temperature and calctination temperature on theactivity of Ni/Al₂O₃ catalyst calcined from 1200 to 1400℃were also investigated.The catalysts were charactered by XRD. The results show that NiAl₂O₄ forms whenthe catalyst was calcined at 1200℃. When the reduction temperature is below800℃, the catalyst exhinbits poor activity because NiAl₂O₄ could not be reduced atthat temperature. When the reduction temperature is 800℃, some NiAl₂O₄ could bereduced to Ni⁰ and the catalyst become more active for partial oxidation of methane.The catalyst exhibits the best activity when the reduction temperature is 900℃because all the NiAl₂O₄ could be reduced to Ni⁰. When the calcinatio is in the range of 1200 to 1400℃, the crystal size of NiAl₂O₄ increases with the increasing of thecalcination temperature, thus NiAl₂O₄ becomes more and more harder to reduce. Sothe activity of the catalyst decreases with the increasing of the calcinationtemperature. When La was added to Ni/Al₂O₃ catalyst, La-Ni/Al₂O₃ exhibits betteractivity for partial oxidation of methane, it is plausible that La can effectivelyinhibit the increasing of the NiAl₂O₄ crystal size.Ni/CeO₂-ZrO₂-Al₂O₃ catalysts for partial oxidation of methane weresuccessfully prepared and the catalysts were characterized by XRD, BET, TPR andXPS methods. The catalytic performance and carbon deposition over the catalystswere investigated in partial oxidation of methane as well. The results show thatNi/CeO₂-ZrO₂-Al₂O₃ catalysts have large BET area, excellent NiO dispersionwhich notably inhibits carbon deposition over the catalysts. All of these factorsmake the catalysts display high activity and good coking resistance and maintainlong-time stability in partial oxidation of methane. The coking resistant ofNi/CeO₂-ZrO₂-Al₂O₃ increases with the increasing of the Al content which canstrengthen the interaction between the active site and the support.更多还原