分步沉淀法制备铜锌基甲醇合成催化剂及其性能研究OA北大核心CSTPCD
Preparation of copper-zinc based methanol catalysts synthesized by stepwise precipitation method and their performance study
铜锌完全共沉淀方法是制备铜锌基甲醇合成催化剂的常用方法,然而该方法难以实现对催化剂表面铜-氧化锌交界面活性位点的构筑调控.为了解决这一问题,采用分步沉淀法,在催化剂整体锌含量一定的前提下,将催化剂的锌组分一部分与铜共沉淀形成内核,一部分在外包覆形成表面铜-氧化锌交界面位点,并研究了不同锌包覆比例对催化剂性能的影响.分别采用X射线衍射(XRD)、N2吸/脱附、X射线光电子能谱(XPS)和H2程序升温还原(H2-TPR)等方法对催化剂的晶粒尺寸、孔道结构、金属价态、电子结构和还原能力等进行了表征分析.结果表明,采用分步沉淀法合成的催化剂比共沉淀法合成的催化剂具有更小的晶粒尺寸、更丰富的孔道结构、更强的铜锌相互作用、更稳定的低价铜位点以及更强的还原能力.甲醇合成性能结果显示,在250℃、5.0 MPa和空速10000 h-1的条件下,锌包覆比例为25%时,催化剂的甲醇合成初活性和耐热后活性达到最优.相比于共沉淀法合成的催化剂,其初活性和耐热后活性分别提升了6%和13%.锌包覆比例为50%时,催化剂的耐热后活性衰退率最低,仅为共沉淀法合成的催化剂的66%.分步沉淀法合成的催化剂的活性和耐热性能均有大幅度提升,该方法实现了对甲醇合成催化剂表面活性位点的有效调控,从而成功提升了铜锌基甲醇合成催化剂的活性和热稳定性.
Copper-zinc coprecipitation method is a commonly used method for preparing copper-zinc based methanol synthesis catalysts,but this method is difficult to achieve the construction and regulation of copper-zinc oxide interface active sites on the surface of catalysts.To solve this problem,a stepwise precipitation method was applied.Keeping the overall Zn content unchanged,a part of zinc was co-precipitated with copper to form a bulk core,while a part of zinc was coated on the particle surface to form copper-zinc oxide interface sites.The influence of Zn coated ratios on the catalyst performance was studied.X-ray diffraction(XRD),N2 adsorption/desorption,X-ray photoelectron spectroscopy(XPS)and H2 temperature programmed reduction(H2-TPR)were used to analyze the particle sizes,pore properties,valence and electronic properties and reducing abilities.The results show that the catalysts synthesized by stepwise precipitation method have smaller particle sizes,richer pore structures,stronger copper-zinc interactions,more stable low valent copper sites and greater reductive capacity,compared with the catalyst synthesized by co-precipitation method.The methanol synthesis results show that the initial activity and the activity after a thermal treatment of catalyst are optimal when 25%zinc is encapsulated under the reaction conditions of 5.0 MPa,250℃and the space velocity of 10000 h-1.The initial activity increases by 6%and activity after thermal treatment increases by 11%,compared with the catalyst synthesized by co-precipitation method.When 50%zinc is encapsulated,the activity degradation rate of the catalyst after thermal treatment is the lowest(14.1%),which is only 66%of that of the catalyst synthesized by co-precipitation method.The activity and thermal stability of catalysts synthesized by stepwise precipitation have been significantly improved.This method achieves effective regulation of the active sites on the methanol catalyst surface,so as to successfully improve the activity and thermal stability of the copper-zinc based methanol catalysts.
陈海波;刘明;李晓敏;于杨;史志刚;李忠于
中石化南京化工研究院有限公司,江苏 南京 210048
化学工程
甲醇合成催化剂活性分步沉淀
methanol synthesiscatalystreactivitystepwise precipitation
《低碳化学与化工》 2024 (005)
8-14 / 7
中国石化技术开发项目(222206).
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