摘要:
采用共沉淀浸渍法,制备了直接合成二甲醚的Cu-Mn-Zn催化剂,通过对组成成分及其配比的研究,发现Cu含量一定的条件下,n(Zn)/n(Mn)摩尔比对催化剂性能有较大的影响,当n(Zn)/n(Mn)=1/3～1/2时,催化剂对CO的转化率和对二甲醚的选择性达到最佳,分别为53.6%和63.5%；如锰添加比例过大,对催化剂催化合成二甲醚有微弱抑制；添加锌比例过大,会大大降低CO的转化率。载体Y分子筛的含量对催化剂性能也有影响,用量过大将降低催化剂的活性和对二甲醚的选择性,当其含量为33%时,催化剂上CO转化率和选择性可分别达到66%和68%,且催化剂活性随分子筛含量减少不再有明显的变化。
Abstract:
Cu-Mn-Zn/Y catalyst prepared by the co-precipitation impregnation method for the synthesis of DME was investigated. It was found that the molar ratio of Zn to Mn had great effect on the activity and selectivity of the catalyst. The superfluous Mn content restrained the synthesis of DME faintly. The excess content of Zn lowered the conversion of CO greatly. The zeolite Y influenced the activity of dehydrating component and the proportion of Cu-Mn-Zn content in combination of the catalyst. The surplus Y-zeolite reduced the conversion of CO and the selectivity of DME. From this results, when the ratio of n(Zn)/n(Mn) was 1/3～1/2 and the content of Y-zeolites was 33% in the Cu-Mn-Zn/Y catalyst, the CO conversion and the DME selectivity reached 66% and 68%, respectively, at the conditions of 245 ℃. 2.0 MPa, 1500 h-1 and V(H2)/V(CO)=1.5. When the CO conversion and the DME selectivity were taken into all-around account, the best reaction temperature was about 260 ℃.
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