OMS-2/堇青石整体式催化剂的制备及其对二甲醚燃烧的催化性能

 以有机物为粘合剂, 采用涂覆法制备了氧化锰八面体分子筛 (OMS-2)/堇青石整体式催化剂, 采用热重-差热分析、扫描电镜、X 射线衍射、H2 程序升温还原和 O2 程序升温脱附等技术对催化剂进行了表征, 考察了有机粘合剂种类及其用量对二甲醚 (DME) 催化燃烧性能的影响. 结果表明, 在有机粘合剂聚乙烯醇 1799 (其质量含量为 3%) 的作用下, OMS-2 以相互交织的簇体均匀分布于堇青石表面, 且粘附力较强, 制备的整体式催化剂在 DME 催化燃烧中表现出最优的催化性能, 起燃温度 T10 = 169 oC, 完全转化温度 T90 = 243 oC; 催化剂使用后再经高温焙烧其活性仍能保持稳定, 表现出较高的重复使用性.

Preparation of OMS-2/Cordierite Monolithic Catalysts and Their Catalytic Performance for Dimethyl Ether Combustion

Manganese oxide octahedral molecular sieve (OMS-2)/cordierite monolithic catalysts were prepared by a coating method using poly(vinyl alcohol) (PVA) or poly(ethylene glycol) (PEG) as the binders. The catalysts were characterized by thermogravimetry-differential thermal analysis, scanning electron microscopy, X-ray diffraction, H2 temperature-programmed reduction (H2-TPR), and O2 tempera-ture-programmed desorption (O2-TPD). The catalytic activity of the catalysts in dimethyl ether (DME) combustion was evaluated. OMS-2 could be loaded on the cordierite with good adhesion stability by the coating method. OMS-2 was in a cluster form and was homogeneously dispersed on the surface of the support. The O2-TPD and H2-TPR results showed that the monolithic catalysts were rich in facile lattice oxy-gen and can activate oxygen and be easily reduced by H2, which led to excellent performance in the DME catalytic combustion. The catalyst with 3% PVA-1799 showed the highest catalytic activity for DME combustion with a light-off temperature (T10) of 169 oC and a complete combustion temperature (T90) of 243 oC. The T90 was raised to 302 oC over the used catalyst after being recalcined at 550 oC for 5 h, but the catalytic activity remained stable after nearly 100 h on stream with recycling 9 times. This indicated that the catalyst was recyclable.