酸碱性硅溶胶对浆状Cu/Zn/Al催化剂性能的影响  

Influence of acid and alkaline silica sol on the performance of Cu/Zn/Al slurry catalysts

作　　者：孙凯[1] 张小雨[1] 张琳[1] 边仲凯 黄伟[1] 赵志换[2] 

机构地区：[1]太原理工大学煤科学与技术教育部和山西省重点实验室,山西太原030024 [2]太原理工大学化学与化工学院,山西太原030024

出　　处：《燃料化学学报》2015年第10期1221-1229,共9页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金重点项目(21336006);国家自然科学基金面上项目(21176176);高等学校博士学科点专项(优先发展领域)(20111402130002)资助~~

摘　　要：在完全液相法研究发现的基础上,选用酸、碱性硅溶胶,制备Cu/Zn/Al/Si浆状催化剂,采用X射线衍射(XRD)、氢气程序升温还原(H2-TPR)、红外光谱分析(FT-IR)、氮气吸附、氨气程序升温脱附(NH3-TPD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)等对催化剂进行了表征。结果表明,两类硅溶胶引入Cu/Zn/Al催化体系后,与前驱体制备环境一致的酸性硅溶胶能显著提高催化剂的CO的转化率和二甲醚的选择性,最高分别可达65.38%和76.26%。酸性硅溶胶削弱了Cu与其他组分的相互作用力,催化剂表现为易于还原、晶粒度大,暴露出丰富的反应所需的Cu0活性晶面。此外,硅溶胶的酸碱性质还改变催化剂酸中心的强度和数量且使强、弱酸中心均向低温方向迁移,酸性硅胶制备的催化剂中弱酸中心数量多,进而提高了催化剂活性和二甲醚的选择性。大比表面积和介孔孔隙丰富的催化剂孔结构亦有利于催化剂活性和二甲醚选择性的提高。A series of Cu/Zn/Al/Si slurry catalysts were prepared by the complete liquid-phase technology with acid and alkaline silica sol in the paper. The catalysts are characterized by means of XRD, H2-TPR, FT-IR, BET, NH3-TPD, XPS and TEM. When the acid silica sol is added, which has the similar environment with the process of precursor preparation, the conversion of CO and selectivity of dimethyl ether reach maxiumum, being 65.38% and 76.26% respectively. The acid silica sol weakens the force between Cu and other components, resulting in the Cu component is easy to be reduced and more active lattice planes of Cu0 on the catalyst are exposed. The acid/alkaline properties of silica sol influence acid site strength and the number of acid sites of catalysts and make both strong acidic sites and the weak acidic sites migrate to lower temperature position. In DME synthesis reaction, it is found that the acid silica sol can increase the ratio of the weak acidic sites to the strong acidic sites on the catalysts, which promotes dehydration performance of methanol and the selectivity of DME. In addition, the catalysts with large specific surface area and mesoporous pore structure are favorable for the activity and selectivity of DME.

关 键 词：完全液相法 酸碱性 硅溶胶 二甲醚 Cu/Zn/Al催化剂 

分 类 号：O643[理学—物理化学]