摘要
本文研究了SO_2对复合氧化物的硫中毒问题。通过催化剂设计、并经实验确证,在γ-氧化铝载体上的铜钒系复合氧化物催化剂具有显著的抗硫性能和良好的活性。为了进一步验证和阐明铜钒系复合氧化物催化剂的抗硫性能,制备了CuO、5CuO+V_2O_5、Cu_3V_2O_8、β-Cu_2V_2O_7、CuV_2O_6、V_2O_5等具有一定组成和晶型结构的模型催化剂,详细考察了它们的硫中毒及复活性能,发现Cu_3V_2O_8具有较好的活性和最佳的抗硫中毒性能。根据CuO、Cu_3V_2O_8的晶型结构特征,解释了它们在硫中毒过程及活性复活过程中的不同实验现象,并初步探讨了铜钒系复合氧化物催化剂的抗硫机制。
SO2 is a strong poison for CO oxidation over perovskite type oxides and other oxides. The problem of sulfur poisoning has become a serious obstacle for replacing noble catalyst by these oxides. In this paper, a supported Cu-V compound oxide catalyst which possesses notable sulfur-resistant property was designed. It is found that the optimum ratio of CuO/V2O5 is 1/0. 4. In our laboratory, when 50 ppm SO2 is added into the gas mixture at 400℃, for the alumina supported catalyst of this CuO/V2O5 ratio, the conversion of CO (original conversion is 100%) decreases and then tends to be stable. The stabilized activity is about 80%. This conversion stays constant over 100 h. But other oxides supported on alumina almost deactivated in about 24 h.. Moreover, it is found that the stable activity increases with the increase of the reaction temperature and the decrease of the SO2 content in the reaction gas. When the SO2 content is reduced successively to zero, the conversion of CO not only increases gradually (the release of SO2 is detected in the tail gas), but also can be restored to 96%. It is indicated that the adsorption of SO2 on the catalyst surface is a reversible adsorption.
In order to verify and expound the sulfur-resistant property of Cu-V compound oxide cataylst, model catalysts with specific composition and structure such as CuO, 5CuO + V2O5, Cu3V2O8, β-Cu2V2O7, CuV2O6 etc. were prepared and identified by XRD. The activity, sulfur poisoning and revivification of these model catalysts were studied in detail. It is found that Cu3V2O8 possesses a fairly good activity and optimum sulfur-resistant property. According to the crystal structure of CuO and Cu3V2O8, the different experimental results in sulfur poisoning and reactivating process were explained. In addition, a preliminary sulfur-resistant mechanism for the Cu-V compound oxide was proposed.
出处
《分子催化》
EI
CAS
CSCD
1992年第2期136-147,共12页
Journal of Molecular Catalysis(China)
关键词
CO氧化
铜钒氧化物
催化剂
硫中毒
CO oxidation, Cu-V compound oxide catalyst, Sulfur poisoning.
