摘要
采用浸渍法制备了经硼、磷和硫的含氧酸根阴离子改性的γ-Al2O3,以其为甲醇脱水活性组分,与铜基甲醇合成活性组分CuO-ZnO-Al2O3组成双功能催化剂,并在连续流动加压固定床反应器上考察了催化剂对合成气直接制二甲醚反应的催化性能.结果表明,SO42-改性可以显著提高γ-Al2O3的甲醇脱水活性,从而提高产物中二甲醚的选择性和一氧化碳的转化率.此外,还详细研究了SO42-改性条件如SO24-含量、焙烧温度及前驱物种类的影响.结果表明,当SO42-含量为10%,焙烧温度为550℃时,二甲醚的选择性及一氧化碳的转化率最高;SO2-前驱物的种类对其改性效果的影响很小.
A series of γ-Al2O3 samples modified with borate, phosphate, and sulfate were prepared by the impregnation technique and physically mixed with a methanol synthesis component （CuO-ZnO-Al2O3） at a mass ratio of 1 ： 2 to form hybrid catalysts. The direct synthesis of dimethyl ether （DME） from syngas was carried out over the prepared hybrid catalysts under pressurized fixed-bed continuous flow conditions. The results indicated that the modification of γ-Al2O3 with SO4^2- could significantly enhance the activity for methanol dehydration and hence remarkably increase the selectivity for DME and the conversion of CO. The effects of SO4^2- content, calcination temperature, and type of SO4^4- precursor on the performance of the SO4^2-/γ-Al2O3 hybrid catalyst were further investigated. The results revealed that the selectivity for methanol decreased when the content of SO4^2- increased from 5 % to 10 %, resulting in the increase in both the selectivity for DME and the conversion of CO. However, when the SO4^2- content was further increased to 15 %, although the activity for methanol dehydration was increased continuously, the selectivity for DME decreased slightly due to the increased formation of byproducts hydrocarbons and CO2. Moreover, when the calcination temperature of SO4^-/γ-Al2O3 increased from 350 to 550 ℃, both the CO conversion and the DME selectivity increased gradually, resulting from the decreased formation of CO2. Nevertheless, a further increase in calcination temperature of SO4^2-/γ-Al2O3 to 750 ℃ resulted in a significant decline in both DME selectivity and CO conversion because of the decreased activity for methanol dehydration. On the other hand, the type of SO4^2- precursors exerted no noticeable influence on the performance of the prepared hybrid catalysts.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2006年第6期515-521,共7页
基金
中国石油化工股份有限公司科技发展基金(200002)
上海市重点学科建设基金(P1501)资助项目
关键词
合成气
二甲醚
双功能催化剂
甲醇
脱水
氧化铝
改性
syngas
dimethyl ether
hybrid catalyst
methanol
dehydration
alumina
modification
