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本文通过改进的水热法制备了孔径较大的有序介孔SBA-15,其孔径(Dp)为10.1 nm,并采用浓盐酸、三甲基氯硅烷(TMCS)和3-氨丙基三乙氧基硅烷(APTES)对SBA-15表面进行了羟基、甲基和氨基改性处理。以嫁接不同表面官能团的SBA-15为模板,合成了一系列菱方晶系钙钛矿型介孔La_(0.8)Sr_(0.2)CoO_3氧化物,系统地研究了模板SBA-15的表面性能对La_(0.8)Sr_(0.2)CoO_3氧化物结构和性能的影响。X射线衍射(XRD)图谱表明,外表面引入―CH_3,内表面羟基化和引入―NH_2的模板有利于合成结晶度较高的、物相单一的钙钛矿结构氧化物。小角XRD图谱、高分辨率透射电子显微镜(HRTEM)图像以及N2吸附测试结果表明,所制备的催化剂为介孔结构。CO氧化的催化活性测试表明,采用表面改性的模板合成的La_(0.8)Sr_(0.2)CoO_3氧化物表现出较高的催化活性和稳定性,在140℃时可以实现CO的完全转化,连续使用100 h后催化剂的催化活性几乎没有下降。X射线光电子能谱(XPS)、H_2程序升温还原(H_2-TPR)和O_2程序升温脱附(O_2-TPD)测试结果表明,催化剂表面丰富的吸附氧物种,高价态的Co离子,钙钛矿结构中Sr在表面富集,及优良的低温氧化还原性是催化活性提高的主要原因。
In this paper, an ordered mesoporous SBA-15 with large pore diameter (Dp) of 10.1 nm was prepared by the improved hydrothermal method and was characterized by concentrated hydrochloric acid, trimethylchlorosilane (TMCS) and 3-aminopropyltris Ethoxy silane (APTES) SBA-15 surface hydroxyl, methyl and amino modified. A series of orthorhombic La_ (0.8) Sr_ (0.2) CoO_3 oxides with rhombic perovskite structure were synthesized by grafting SBA-15 with different surface functional groups. The surface properties of template SBA-15 Effect of La_ (0.8) Sr_ (0.2) CoO_3 Oxides on Structure and Properties. X-ray diffraction (XRD) patterns show that the introduction of -CH 3 on the outer surface, the hydroxylation of the inner surface and the introduction of -NH 2 are favorable for synthesizing perovskite structure oxides with high crystallinity and single phases. Small angle XRD patterns, high resolution transmission electron microscopy (HRTEM) images and N2 adsorption test results show that the prepared catalyst is a mesoporous structure. The catalytic activity of CO oxidation showed that La_ (0.8) Sr_ (0.2) CoO_3 oxide synthesized by surface modification showed high catalytic activity and stability. The complete conversion of CO was achieved at 140 ℃. After 100 h, the catalytic activity of the catalyst showed almost no decrease. X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR) and O 2 -TPD measurements showed that the surface of the catalyst was rich in oxygen species, high-valent Co ions and perovskite Structure Sr enrichment on the surface, and excellent low temperature redox activity is the main reason for the increase in catalytic activity.