镁掺杂氧化铈整体式催化剂催化CO_(2)和CH_(3)OH直接合成碳酸二甲酯

Direct Synthesis of Dimethyl Carbonate from CO_(2) and Methanol by Mg-Doped Ceria Monolithic Catalyst

采用共沉淀法成功地合成了不同Mg掺杂量的Ce_(1-x)Mg_(x)O_(2)(x=0.05、0.10、0.15、0.20)固溶体催化材料,并运用透射电子显微镜(TEM)、X射线衍射(XRD)、氮气吸附-脱附测试、拉曼光谱、X射线光电子能谱(XPS)、CO_(2)程序升温脱附(CO_(2)-TPD)等技术对这些材料进行了表征。结果发现,通过调控CeO_(2)晶格中Mg的含量,可以调控所制备的Ce_(1-x)Mg_(x)O_(2)催化材料的粒径、比表面积、表面缺陷等。其中Ce_(0.90)M_(g0.10)O_(2)展现了最佳的表面性质,具有最小的平均粒径(约5.8 nm),最大的比表面积(约136 m^(2)·g^(-1))以及最高的表面氧含量(31.98%)。将Ce_(1-x)Mg_(x)O_(2)催化材料涂覆在堇青石蜂窝陶瓷上制成整体催化剂,考察其对CO_(2)和CH3OH直接合成碳酸二甲酯的催化性能。在140℃、2.4 MPa、反应2 h的条件下,Ce_(1-x)Mg_(x)O_(2)整体催化剂上碳酸二甲酯的收率高达20.21%,催化效果明显优于CeO_(2)和其余的Ce_(1-x)Mg_(x)O_(2)(x=0.05、0.15、0.20)催化材料。

In this paper, Ce_(1-x)Mg_(x)O_(2)(x=0.05, 0.10, 0.15, 0.20) solid solution catalytic materials with different molar ratios were successfully synthesized by co-precipitation method. These materials were characterized by transmission electron microscope(TEM), X-ray diffraction(XRD), nitrogen adsorption-desorption test, Raman spectroscopy, Xray photoelectron spectroscopy(XPS), CO_(2)temperature-programmed desorption(CO_(2)-TPD) and other techniques. It was found that the particle size, specific surface area, surface defects, etc. of the prepared Ce_(1-x)Mg_(x)O_(2)catalytic materials can be tuned by regulating the content of Mg in the CeO_(2)lattice. Among them, Ce_(0.90)M_(g0.10)O_(2)exhibited the best surface properties, with the smallest average particle size of about 5.8 nm, the largest specific surface area of about 136 m^(-2)·g^(-1), and the highest surface oxygen content(31.98%). Ce_(1-x)Mg_(x)O_(2)catalytic material was coated on the cordierite honeycomb ceramic to make a monolithic catalyst, and its catalytic performance for the direct synthesis of dimethyl carbonate from CO_(2)and CH_(3)OH was investigated. Under the conditions of 140 ℃, 2.4 MPa, and 2 h reaction, the yield of dimethyl carbonate on Ce_(0.90)M_(g0.10)O_(2) monolith catalyst was as high as 20.21%, and the catalytic activity was significantly higher than that of CeO;and other Ce_(1-x)Mg_(x)O_(2)(x=0.05, 0.15, 0.20) catalytic materials.