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开发室温CO氧化催化剂的主要挑战是CO自中毒和慢的表面动力学,同时湿气的存在也可导致催化剂失活.本文开发了高活性CeO_2促进的Pt基催化剂4%Pt-12%CeO_2/Si O_2,用于室温湿气(湿度10%–90%,25°C)中CO氧化反应,在低CO浓度(<500 ppm)和高CO浓度(>2500 ppm)时,CO转化率高于99%.优化了催化剂制备变量,如Pt和CeO_2负载量、CeO_2沉积方法、CeO_2和Pt前驱体的干燥和焙烧条件.采用CO/H_2化学吸附、O_2-H_2滴定、X射线衍射和BET比表面积测定表征了催化剂的表面特性,并将其与催化剂活性相关联.结果表明,CeO_2沉积方法对催化剂活性影响显著,当用浸渍法沉积CeO_2时,所得催化剂的反应速率(5.77μmol/g/s)比用沉积沉淀法(1.96μmol g~(-1)s~(-1))或CeO_2嫁接法(1.31μmol g~(-1)s~(-1))制得催化剂的高3倍.O_2-H_2滴定结果表明,当用浸渍法沉积CeO_2时,CeO_2和Pt的紧密结合导致了催化剂的高活性.催化剂载体的选择也非常重要,硅胶负载的催化剂活性(5.77μmol g~(-1)s~(-1))是氧化铝负载的(1.05μmol g~(-1)s~(-1))5倍.当反应受内扩散控制时,催化剂载体的粒径和孔结构影响非常大.另外,CeO_2和Pt前驱体的干燥和焙烧条件对催化剂活性的影响至关重要.当Pt和CeO_2含量分别大于2.5和15 wt%时,所得催化剂在室温条件下活性高(TOF>0.02 s~(-1)),稳定性好(反应15 h,CO转化率≥99%).
The main challenges of developing room temperature CO oxidation catalysts are self-poisoning and slow surface kinetics of CO, and the presence of moisture can also lead to catalyst deactivation.In this paper, high activity CeO 2 promoted Pt-based catalyst 4% Pt-12% CeO 2 / Si O 2 for CO oxidation in room temperature humidity (humidity 10% -90%, 25 ° C), CO conversion higher than low CO concentration (<500 ppm) and high CO concentration (> 2500 ppm) 99% .The catalyst preparation variables such as Pt and CeO 2 loadings, CeO 2 deposition methods, CeO 2 and Pt precursor drying and calcination conditions were optimized.Using CO / H 2 chemisorption, O 2 -H 2 titration, X-ray diffraction and BET specific surface area The results showed that the CeO 2 deposition method had a significant effect on the catalyst activity. When the CeO 2 was deposited by impregnation method, the reaction rate of the obtained catalyst (5.77 μmol / g / s) The catalyst was 3 times higher than that prepared by deposition precipitation (1.96 μmol g -1 s -1) or CeO 2 grafting (1.31 μmol g -1 s -1) The results of -H 2 titration showed that the close combination of CeO 2 and Pt resulted in the high activity of the catalyst when CeO 2 was deposited by impregnation method. Importantly, the silica supported catalyst activity (5.77 μmol g -1 s -1) was 5 times that of alumina supported (1.05 μmol g -1 s -1) In the inner diffusion control, the particle size and pore structure of the catalyst support is very large.In addition, the drying and calcination conditions of CeO_2 and Pt precursors are crucial for the activity of the catalyst.When the content of Pt and CeO_2 is more than 2.5 and 15 wt% , The obtained catalyst has high activity (TOF> 0.02 s -1) at room temperature, good stability (reaction 15 h, CO conversion ≥99%).