Preparation of Ag foam catalyst based on in-situ thermally induced redox reaction between polyvinyl alcohol and silver nitrate with supercritical CO2 foaming technology
Preparation of Ag foam catalyst based on in-situ thermally induced redox reaction between polyvinyl alcohol and silver nitrate with supercritical CO2 foaming technology
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DOI：
10.1016/j.polymer.2020.122858
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发表时间：
2020-10
期刊：
影响因子：
4.6
通讯作者：
Bin Yuan;Shuangqiao Yang;Meng Wang;J. Xia;Shibing Bai
中科院分区：
文献类型：
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作者：
Bin Yuan;Shuangqiao Yang;Meng Wang;J. Xia;Shibing Bai
传统的泡沫金属催化剂制备工艺繁琐、能耗大、难以规模化生产，制约了其发展。在这项工作中，聚乙烯醇（PVA）作为多羟基还原剂的潜力进行了探索。利用PVA与硝酸银（AgNO 3）的热致氧化还原反应，结合超临界二氧化碳（ScCO 2）发泡技术，提出了制备微米级银泡沫催化剂的创新思路。首先，利用H2O和AgNO 3的复合增塑作用，以CO2为发泡剂，在100 °C以下制备出结构均匀的PVA/AgNO 3复合泡沫。最大细胞密度可达5.39 × 109个/cm 3，平均细胞尺寸可达8.27 μm。然后，以PVA为还原剂和牺牲模板，在较低温度（160-210 °C）下原位快速还原银离子，得到的银粒子自组装成泡沫状骨架结构。银泡沫具有可调的多孔结构，泡孔尺寸为4.01-16.30 μm，韧带尺寸为1.08-2.82 μm。将其作为催化剂用于促进4-硝基苯酚（4-NP）的还原，催化反应速率常数是现有商业银泡沫的10倍。制备的泡沫银催化剂具有用量少、易回收、稳定性好的优点。在传感、生物医学、热传导等领域也有很大的应用潜力。
The preparation process of a traditional metal foam catalyst is cumbersome, energy-intensive, and difficult to scale production, which restricts its development. In this work, the potential of polyvinyl alcohol (PVA) as a polyhydroxy reductant was explored. We used the thermally induced redox reaction between PVA and silver nitrate (AgNO3), combining with supercritical carbon dioxide (ScCO2) foaming technology, proposing an innovative idea for preparing the micron-sized Ag foam catalyst. Firstly, through the compound plasticizing effect of H2O and AgNO3, using CO2as foam agent, the PVA/AgNO3composite foams with uniform structure could be prepared below 100 °C. The maximum cell density could reach 5.39*109cells/cm3and the average cell size could reach 8.27 μm. Then, using the PVA matrix as a reductant and self-sacrifice template, silver ions could be quicklyin-situreduced at lower temperature (160–210 °C), the resulting silver particles could self-assemble into a foam-like skeleton structure. The Ag foams have an adjustable porous structure with a cell size of 4.01–16.30 μm and a ligament size of 1.08–2.82 μm. Applying it as a catalyst to promote the reduction of 4-nitrophenol (4-NP), the catalytic reaction rate constant is 10 times that of existing commercial Ag foam. The prepared Ag foam catalyst has the advantages of less dosage, easy recovery and good stability. Also, it has great application potential in the sensing, biomedicine, heat conduction and other fields.