【摘要】 采用共沉淀沉积法制备了一种适用于富碳合成气一步法合成二甲醚(DME)的高活性催化剂C207-HZSM-5。考察了催化剂配比、还原条件、反应温度等对催化剂性能的影响,并采用程度升温还原(TPR)方法及XRD表征,对催化剂的还原性能及催化剂氧化态、还原态、反应后的物相结构进行了分析。结果表明,还原时,低升温速率有利于催化剂活性的提高。在p=3MPa、T=280℃、空速为3000mL/(g·h)条件下,CO转化率为66.03%,DME收率为45.5%,接近其热力学平衡值。结合活性评价结果及不同还原温度下的XRD结果得出,Cu+是催化剂的主要活性物种。TPR结果表明,还原分两步进行,即165℃处的Cu2+还原至Cu+过程,和175℃处的少量的Cu+还原至Cu0过程。更多还原

【Abstract】 Catalyst C207-HZSM-5 prepared by coprecipitation deposition showed high catalytic activity for dimethyl ether synthesis from syngas rich in carbon monoxide. The effect of the ratio of C207 to HZSM-5 by weight, reduction conditions and reaction conditions, on the catalytic activity were investigated. In addition, the reduction and the crystal structures of catalysts in oxidized, reduced and used states were scanned by temperature-programmed reduction(TPR) and XRD. The results show that the conversion of CO and the yield of DME are 68.13%and 47% close to their thermodynamic equilibrium data at 280 ℃for the temperature, 3 MPa for the pressure, 3 000mL/(g·h) for the space velocity. Combining the catalytic activity data and results of XRD characterization, the main active site of catalyst is considered as Cu~+. From the results of TPR, the reduction of catalyst can be described that Cu~2+is reducedto Cu~+at 165 ℃, followed by a little Cu~+is reduced to Cu~0at 175 ℃.更多还原