摘要催化氧化 NO 是目前烟气脱氮技术研究方向之一。本论文以 CrOx 为活性组分, 分别进行前驱体改性及掺杂稀土金属 Ce 制得催化氧化 NO 的催化剂,载体选择目 前广泛应用的钛交联粘土(Ti-PILC)。分别考察前驱体改性及掺杂 Ce 之后催化 剂的脱硝性能。68564
首先,使用 H2O2 对前驱体进行改性。比较不同 Cr/H2O2 摩尔比的催化剂的活 性,当摩尔比为 3 时活性最佳。改性后催化剂的活性总体均高于 Cr/Ti-PILC 催化 剂。通过 XRD、TPD、DRIFTS 等表征分析前驱体改性后催化剂性能提高的原因。 H2O2 的改性使高价态 CrOx 含量增加,而高价态的 CrOx 有益于 Cr/Ti-PILC 催化 剂上 NO 上的吸附,从而提高了催化剂的活性。
其次,掺杂 Ce 后催化剂的活性明显的提高。Cr0.8Ce0.2/Ti-PILC 催化剂在 NO 选择性催化氧化中的活性温度窗口变宽,290-350℃温度范围内都具有较高的活 性。XRD、TPD 和 XPS 等表征结果表明 Ce 的掺杂使得氧流动性变强, Ce 价态 的转变使得电子失去平衡,促进了电子的移动,并产生氧空位,促进化学吸附氧 的形成。
毕业论文关键词:NO,Ti-PILC,Cr,H2O2,Ce,催化氧化
Title Preparation,characterization and catalytic oxidation performance research based on Cr/Ti-PILC
Abstract
Cr oxides were used as the active site. The modification of the precursor via H2O2 was carried out in the preparation of the catalyst. Besides, Ce oxides were used as the promoter in the system of the NO oxidation. The first part of our research was to modify the precursor via H2O2. The Cr-HP(x)/Ti-PILC catalyst showed the best activity when the molar ratio was 3. The gradual increase in NO conversion with temperature was observed over all the catalysts in general. To analyze the reason of the improvement of the catalyst performances, the XRD 、 TPD 、 DRIFTS were used in the experiment. The content of higher valence states of chromium oxides was increased, which was beneficial to the adsorption of NO on Cr/TI-PILC catalyst. The second part was about the promotion effect of Ce. A series of chromium-ceria doped on Ti-PILC nanocomposites catalysts with various Cr/Ce ratios were investigated in the oxidation of NO. The Cr0.8Ce0.2/Ti-PILC had a widener temperature window in the selective catalytic oxidation of NO. The ease of formation of labile oxygen vacancies and particularly the relatively high mobility of bulk oxygen species of CeOx could increase the concentration of chemisorbed oxygen.
Keywords Nitric oxide, Ti-PILC, Cr oxides, Catalytic oxidation, H2O2, Ce
目 录
1.前言 1
1.1 课题研究背景与意义 1
1.1.1 NOX 的危害 1
1.1.2 NO 控制技术 1
1.2 选择性催化氧化技术 2
1.2.1 催化氧化方法 2
1.2.2 催化氧化催化剂 2
1.2.3 钛交联粘土载体的研究进展 3
1.3 论文的研究思路和研究内容 3
1.3.1 研究思路 3
1.3.2 研究内容 4
2 前驱体改性 Cr/Ti-PILC 催化剂的制备及性能研究 5
2.1 实验部分 5
2.1.1 实验试剂和主要仪器