共沉淀法制备Cu-Mn-Al尖晶石催化剂用于甲醇水蒸气重整制氢

Preparation of Cu-Mn-Al spinel catalyst by co-precipitation method for methanol steam reforming

摘要:

以硝酸铜、硝酸铝和硝酸锰为原料，用共沉淀法制备了Cu-Mn-Al尖晶石固溶体催化剂，用于甲醇水蒸气重整制氢反应。采用BET、H2-TPR、XRD、SEM、XPS等方法对催化剂进行表征,考察了Mn的添加比例(CuMnxAl4-x , x =0~0.5)对催化剂物理化学性质、形貌及催化性能的影响。结果表明，锰添加比例不同，催化剂的比表面积、还原性能以及表面化学性质改变，随着锰比例从0增大到0.5 (以铜的物质的量为基准)，CuAl尖晶石粒径增大，比表面积下降，并且更难被还原。催化剂的催化性能在x=0.25时最佳，在260℃、0.3MPa、n(H2O)∶n(CH3OH)=1∶1、质量空速(WHSV)为3.0g-feed/g-cat/h的反应条件下，最高甲醇转化率为91.7%，连续运行150h后甲醇转化率降至78.8%，均明显高于未含Mn的CuAl尖晶石催化剂。

Abstract:

Cu-Mn-Al spinel solid solution catalysts were prepared by coprecipitation method using copper nitrate, aluminum nitrate and manganese nitrate, and tested in methanol steam reforming reaction for the preparation of hydrogen. The catalysts were characterized by BET, H2-TPR, XRD, SEM, XPS, etc. The effects of Mn ratio (CuMnxAl4-x , x = 0 ~ 0.5) were investigated on catalyst physicochemical properties, morphology, as well as the catalytic performance. The results showed that the specific surface area, reduction properties and surface chemistry of catalyst samples were altered with Mn ratio. With Mn ratio x rising of from 0 to 0.5 (based on the amount of copper), the specific surface area decreased, the size of spinel particles increased, and became more difficult to reduce. The best performance was found for the catalyst CuMn0.25Al3.75, where under the reaction conditions of 260 ℃, 0.3 MPa, n(H2O)∶n(CH3OH) =1∶1, weight hourly space velocity(WHSV) 3.0g-feed/g-cat/h, the highest methanol conversion attained 91.7% and dropped to 78.7% after 150h running, which are substantially higher than the CuAl spinel catalyst contains no Mn.