浸渍溶液对Pt/PTFE/泡沫SiC规整疏水催化剂性能的影响

Influence of impregnation solution on the performance of Pt/PTFE/foam-SiC-structured hydrophobic catalyst

Pt/PTFE/泡沫SiC规整疏水催化剂可用于氢-水液相催化交换反应(Liquid-phase catalytic exchange process,LPCE)进行水去氚化(Water detritiation system,WDS)。为研究浸渍溶液对该催化剂性能的影响,以丙酮、乙二醇、无水乙醇分别配制不同的氯铂酸-有机溶液,直接浸渍具有疏水性的PTFE/泡沫SiC,250°C气相还原,从而制备Pt/PTFE/泡沫SiC规整疏水催化剂。利用X射线衍射分析(X-ray diffraction,XRD)、X射线光电子能谱分析(X-ray photoelectron spectroscopy,XPS)、透射电子显微镜(Transmission electron microscope,TEM)等表征手段分析所得催化剂的结构与组成,并研究其氢-水液相催化交换性能。三种催化剂的平均粒径分别为9.3 nm、3.6 nm、6.8 nm,乙二醇对Pt粒子有保护作用,得到的平均粒径最小。Pt存在Pt(0)、Pt(II)和Pt(IV)三种价态,氯铂酸-乙醇和氯铂酸-乙二醇制备的催化剂中0价态均为主要价态,Pt(0)比例分别为47.60%和43.97%,氯铂酸-丙酮制备的催化剂中4价态为主要价态。根据LPCE性能测试结果,氯铂酸-乙二醇制备的催化剂柱效率最高,说明催化剂中Pt(0)价态比例接近时,Pt粒子粒径大小对氢-水液相催化交换反应的影响更明显。揭示乙二醇为优选溶剂。

Background： Pt/PTFE/foam-SiC-structured hydrophobic could be used for a water detritiation system （WDS） via a liquid-phase catalytic exchange process （LPCE）. Purpose： To study the influence of impregnation solution on the performance of this catalyst, acetone, ethylene glycol and ethanol were chosen as the solvent to prepare Pt-organic solution, respectively. Methods： The catalysts were prepared by impregnation method with the above three different solutions. The as-prepared catalysts were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, Transmission electron microscope （TEM）, etc. Moreover, their catalytic activity for LPCE was tested. Results： The average particle sizes of Pt particles of the three different catalysts were 9.3 nm, 3.6 nm and 6.8 nm, respectively. The catalyst prepared by chloroplatinic acid-ethylene glycol had the smallest average particle size, because ethylene glycol would protect Pt particles. Three valences, Pt（0）, Pt（Ⅱ） and Pt（Ⅳ） existed in these catalysts, and Pt（0） was the key for catalytic isotope exchange. Pt（0） was the main valences in the catalysts prepared by chloroplatinic acid-ethanol and chloroplatinic acid-ethylene glycol, and the proportion were 47.60% and 43.97%, respectively. Pt（IV） was the main valence in the catalyst prepared by Chloroplatinic acid-acetone. According to the results of LPCE, the catalyst prepared by chloroplatinic acid-ethylene glycol had the highest column efficiency. Conclusion： The results meant that when the proportions of Pt（0） are close, the Pt particle size was the main factor of influence on LPCE. Thus, ethylene glycol is the best solvent.