介孔CuO/γ-Al2O3催化剂的 制备及其在合成气制二甲醚反应中的应用

以三嵌段共聚物F₁₂₇为模板剂,以异丙醇铝、硝酸铜为原料,采用溶剂挥发自组装法制备具有介孔结构的CuO/γ-Al₂O₃复合催化剂.通过XRD、SEM-EDS、H₂-TPR、N₂-吸附脱附、TEM等技术对该催化剂的结构进行了表征.实验结果表明,通过溶剂挥发自组装法制备的催化剂CuO/γ-Al₂O₃具有有序的介孔结构,并且具有较大的比表面积以及均一的介孔结构,并且Cu元素均匀地分布在γ-Al₂O₃的表面.将该复合催化剂用于合成气直接制备二甲醚的反应,在空速1 500 h^-1、温度320 ℃、压力5 MPa的条件下,CO转化率最高达到68.8%、DME选择性达到59.0%.连续反应50 h后,CO转化率从68.8%降低至59.5%,DME选择性基本保持不变,催化剂部分失活的原因是由于铜元素部分发生了聚集.

Preparation of mesoporous CuO/γ-Al2O3 for one-step synthesis of dimethyl ether from syngas

Solvent evaporation self-assembly method was adopted to synthesize CuO/γ-Al₂O₃ composite catalysts with mesoporous structure using F₁₂₇ as template, aluminum isopropoxide and copper nitrate as precursor. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), H₂ temperature program reduction (H₂-TPR), nitrogen adsorption-desorption and transmission electron microscope (TEM) were used to characterize the properties of the catalysts. The results show that ordered and uniform mesoporous structure as well as large specific surface area were discovered in catalysts with different copper contents. In the syngas to dimethyl ether (DME) reaction, the highest conversion of CO reached 68.8% and the selectivity of DME achieved 59.0% under space velocity of 1 500 h^-1, 320 ℃ and 5 MPa. The conversion of CO decreased from 68.8% to 59.5% after 50 h on stream, and the selectivity of DME kept constant. The partial loss of activity was due to the aggregation of copper on this catalyst.