老化时间对Cu/ZnO/Al2O3合成甲醇催化剂性能的影响

老化时间对Cu/ZnO/Al2O3合成甲醇催化剂性能的影响

  • 摘要: 并流共沉淀法制备了CuO/ZnO/Al2O3催化剂前驱体及催化剂,用XRD、TG-DTG、TPR、N2吸附及加压微反活性评价技术,考察了母料老化时间对催化剂前驱体物相组成及焙烧后物料中CuO-ZnO间的作用和物化性能的影响,提出了催化剂母料物相随老化时间的变化。研究表明,老化时间对催化剂活性的影响是通过改变催化剂比表面积及形成CuOZnO固溶体的结果。

     

    Abstract: The aging process of copperzincaluminum precursors was studied by XRD, TGDTG and TPR techniques. The catalytic activity of CuO/ZnO/Al2O3 catalyst for methanol synthesis were tested using continues flow type fixedbed reactor. For the precursors prepared at the precipitating condition of pH=8.0 and temperature=80℃, the initial phases of the precipitate was a mixture of copper nitrate hydroxide Cu2(OH)3NO3, georgeite(amorphous Cu2CO3(OH)2) and hydrozincite Zn5 (CO3)2(OH)6. By increasing duration of its aging time, the phase of Cu2(OH)3 NO3first transited to georgeite, then interdiffused with Zn5(CO3)2(OH)6, resulting in two new phases: rosasite (Cu,Zn)2CO3(OH)2 and aurichalcite (Cu,Zn)5(CO3)2(OH)6. It was found that the composition and structure of the precursors altered obviously after the colour transition point. The research results demonstrate that the BET surface area and the amounts of CuOZnO solidsolution of the catalyst increased as the aging time extending which in turn to influence the catalytic activity of the catalyst.

     

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