Au-Cu/CO3O4双金属催化剂上乙烯完全催化氧化性能

摘要

A sedes of Au-Cu/Co3O4 catalysts with different mass fractions of Cu were synthesized by a two-step method that consists of depositing gold and copper onto a Co3O4 support, which was synthesized by coprecipitation. The effect of copper on the catalytic activity of Au-Cu/Co3O4 was evaluated for the complete oxidation of ethylene at different temperatures and the prepared catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), H2 temperatureprogrammed reduction (H2-TPR), and O2 temperature-programmed desorption (O2-TPD). The results show that Au-Cu/Co3O4 bimetal catalysts exhibit higher catalytic activities than the Au/Co3O4 catalyst. At a gold loading amount of 4％ (w, mass fraction) the AuCu3/Co3O4 catalyst gives higher catalytic activity compared to catalysts AuCu/Co3O4 and Au3Cu/Co3O4. Ethylene conversion was 15.3％ for AuCu3/Co3O4 even at 0 ℃ whereas at 120 ℃ the full conversion of ethylene was obtained. The results of XRD and HRTEM indicate the formation of an Au-Cu alloy in AuCu3/Co3O4. However, we have found that the majodty of Cu is present in the form of Cu2O in Au3Cu/Co3O4. The interaction between Au and Cu on the surface of the catalysts decreases the particle size of the gold and, therefore, it is much easier to activate ethylene. H2-TPR and O2-TPD results show that the high reduction ability and the high intensity of surface oxygen active species contribute to the excellent catalytic activity of the AuCu3/Co3O4 catalyst.%以共沉淀法制得的Co3O4为载体,采用两步法负载Au和Cu制得了一系列Au-Gu/Co3O4双金属催化剂,考察了Au-Cu/Co3O4双金属催化剂完全催化氧化乙烯的性能,并通过X射线衍射(XRD)、高分辨透射电镜(HRTEM)、H2程序升温还原(H2-TPR)和O2程序升温脱附(O2-TPD)对催化剂进行了表征.活性测试结果表明:负载型Au-Cu/Co3O4双金属催化剂的催化性能优于单一金属催化剂Au/Co3O4,并且在Au负载量为4%(W1质量分数)时,与AuCu/Co3O4和Au3Cu/Co3O4催化剂相比,AuCu/3Co3O4催化剂的催化活性较好,0℃时可催化转化15.3%的乙烯为CO2和H2O,120℃时100%催化转化乙烯.XRD和HRTEM表明,AuCu3/Co3O4催化剂中有Au-Cu合金相的生成,而Au3Cu/Co3O4催化剂中Cu主要以氧化物的形式存在.Au和Cu之间产生相互作用,使活性相金属的粒径降低.H2-TPR和O2-TPD分析结果表明,AuCu3/Co3O4催化剂具有较强的低温可还原能力和可提供的大量表面活性吸附氧物种,促进了乙烯的完全催化氧化.