摘要
负载于多孔性、高比表面载体上的V_2O_5是工业上SO_2、CO及碳氢化合物氧化的催化剂。多年来人们对催化剂中V_2O_5的存在状态进行了广泛的研究,发现非晶相表面层V(Ⅴ)具有较高的催化活性。本文试图根据唐有祺、谢有畅等提出的氧化物在载体表面的自发分散现象。
V2O5/NaY and V2O6/NaM samples with various amounts of V2O5 prepared by mixing V2O5 and NaY(or NaM),and calcining at 500℃ for 24 hours were studied by X-ray diffraction analysis.It is shown that V2O5 can disperse spontaneously onto NaY,NaM zeolites as a non-crystalline layer.The dispersion amount of V2O5 on NaY at 600℃ or on NaM at 650℃ is much more than that at 500℃.The framework of NaY and NaM is destroyed by the dispersed V2O6 because of the surface interaction.At calcination temperatures of 600℃ and above,part of the supported V2OB reacts with NaY (or NaM) to yield a new solid compound.The crystallinity of NaY(or NaM) decreases with increasing the V2O6 loading.
基金
国家自然科学基金
关键词
五氧化二钒
NAY分子筛
NaM分子筛
X-ray diffraction method
vanadium pentoxide
NaY zeolite
NaM zeolite
interaction
