CuO/Ce0.5Ti0.5O2的制备与表征及其对NO+CO反应的催化活性

以Ce0.5Ti0.5O2为载体, 采用浸渍法制备了不同负载量的CuO/Ce0.5Ti0.5O2催化剂, 通过TPR、XRD和激光Raman光谱等技术对其进行了表征, 并在色谱-微反装置上考察了催化剂对NO+CO反应催化性能. 结果表明, CuO/Ce0.5Ti0.5O2催化剂对NO+CO反应的活性与CuO负载量有关; 500 ℃焙烧的催化剂, 当CuO的负载量(w)为22%时, 催化剂的活性最好; 14%CuO/Ce0.5Ti0.5O2在700 ℃焙烧具有最佳催化活性, 这可能与复合载体形成了CeTi2O6的结构有关. TPR结果表明, CuO在Ce0.5Ti0.5O2上出现了四种还原能力不同的物种, α和β峰是载体表面高度分散的CuO物种, γ峰是与Ce0.5Ti0.5O2相互作用较强的孤立CuO晶簇的还原峰, δ峰是载体表面晶相CuO的还原峰; XRD结果表明700 ℃焙烧的样品中已出现了新复合氧化物CeTi2O6的晶相峰, 随焙烧温度的升高, 此晶相峰也变得更加明显, 这说明高温焙烧有利于Ce与Ti发生固相反应而形成CeTi2O6结构; Raman结果表明, 焙烧后的Ce0.5Ti0.5O2并不是简单的TiO2和CeO2的复合, 而是形成了新的晶相结构, 这也进一步验证了CeTi2O6结构的生成.

Preparation and Characterization of CuO/Ce0.5Ti0.5O2 and Its Catalytic Activity for NO+CO Reaction

Using Ce0.5Ti0.5O2 as carrier, CuO/Ce0.5Ti0.5O2 catalysts with different CuO loadings were prepared by the impregnation method. The catalytic activities of the catalysts for NO+CO reaction were examined with a micro-reactor gas chromatography reaction system and the catalysts were characterized by of TPR, XRD, and Raman spectroscopy. It was found that the activity of CuO/Ce0.5Ti0.5O2 for NO+CO reaction was depended on CuO loading, and became maximal when CuO loading was 22% and the calcined temperature was 500 ℃. However, after calcination at 700 ℃ 14%CuO/Ce0.5Ti0.5O2 had the highest activity, possibly due to the formation of CeTi2O6-mixed oxide. The TPR analysis showed that CuO/Ce0.5Ti0.5O2 had four TPRreduction peaks (α, β, γ, and δ peaks). The α and β peaks were the reduction of highly dispersed CuO species; the γpeak was due to the isolated bulk CuO interacted intensively with Ce0.5Ti0.5O2; and the δ peak was due to the bulk CuO on the surface of CuO/Ce0.5Ti0.5O2. As shown by XRD, CuO/Ce0.5Ti0.5O2 calcined at 700 ℃ had new oxide CeTi2O6, and the diffraction peaks of CeTi2O6 became obvious as the calcined temperature increased, indicating that high temperature enhanced solid reaction of Ce and Ti, and formation of CeTi2O6. The Raman results indicated that after calcination Ce0.5Ti0.5O2 was no longer a simple combination of TiO2 and CeO2, but had formed new crystal structure.