催化学报

催化学报 ›› 2019, Vol. 40 ›› Issue (9): 1375-1384.DOI: 10.1016/S1872-2067(19)63378-4

• 论文 • 上一篇    下一篇

分子筛稳定的Cu物种催化乙醇脱氢制乙醛

于东霓a, 戴卫理a, 武光军a, 关乃佳a,b, 李兰冬a,b   

  1. a 南开大学材料科学与工程学院, 国家新材料研究院, 天津 300350;
    b 南开大学先进能源材料化学教育部重点实验室, 化学化工协同创新中心, 天津 300071
  • 收稿日期:2019-02-28 出版日期:2019-09-18 发布日期:2019-07-06
  • 通讯作者: 戴卫理, 李兰冬
  • 基金资助:
    国家自然科学基金（21872072，21573113）；天津市自然科学基金（18JCZDJC37400）；中国石化（417012）.

Stabilizing copper species using zeolite for ethanol catalytic dehydrogenation to acetaldehyde

Dongni Yua, Weili Daia, Guangjun Wua, Naijia Guana,b, Landong Lia,b   

  1. a School of Materials Science and Engineering & National Institute for Advanced Materials, Nankai University, Tianjin 300350, China;
    b Key Laboratory of Advanced Energy Materials Chemistry of the Ministry of Education, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
  • Received:2019-02-28 Online:2019-09-18 Published:2019-07-06
  • Contact: S1872-2067(19)63378-4
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21872072, 21573113), Municipal Natural Science Foundation of Tianjin (18JCZDJC37400) and Sinopec (417012).

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摘要： 生物乙醇作为一种绿色原料，常用于制备具有更高附加值的化学品，如乙烯、丙烯、丁二烯、1-丁醇和乙醛等.其中，乙醛作为重要的化学原料又可以进一步转化生成乙酸，乙酸酯和季戊四醇等。因此，由生物乙醇脱氢制乙醛的可持续路线受到了研究者的广泛关注.在众多催化体系中，Cu基催化剂表现出较高的活性和乙醛选择性，但Cu物种的烧结又会导致催化剂的快速失活.因此，抑制Cu物种的烧结是提高Cu基催化剂稳定性的常用手段.本文通过后合成路线构筑了具有限域效应的Cu/Beta分子筛催化剂，并成功应用于乙醇脱氢制乙醛反应.我们首先考察了Cu的负载量、反应温度和Cu的前驱体对反应的影响，发现以醋酸铜为前驱体的5% Cu/Beta催化剂在乙醇脱氢制乙醛反应中表现出最佳催化性能：催化剂寿命达到100 h，乙醛收率稳定在70%左右（反应条件：300℃，WHSV=1.0 h-1）.XRD，TEM，DRIFT，1H MAS NMR，UV-Vis以及H2-TPR等结果表明以醋酸铜为前驱体的Cu/Beta分子筛上的主要活性中心为CuO物种，并且该物种以高度分散的形式限域在分子筛脱铝产生的硅羟基缺陷位上.因此，在乙醇脱氢制乙醛反应中，限域的Cu/Beta分子筛催化剂与孤立的CuO催化剂相比，具有优异的抗烧结能力.然而，当反应至180 h时，催化剂会有明显的失活现象.再生后，尽管催化剂的初始活性能较好的恢复，但催化剂的寿命却大大下降.我们利用TEM，TGA以及CO-DRIFTS对反应后的催化剂进行表征，发现失活的Cu/Beta催化剂上存在Cu+和Cu0物种，并且伴有大块烧结现象.这表明随着反应的进行，Cu/Beta催化剂上的CuO物种会逐渐还原成Cu+和Cu0物种，而Cu0物种的出现又会诱导烧结现象的发生，进而导致催化剂的失活.

关键词: 乙醇脱氢, 乙醛, 沸石分子筛, Cu基催化剂, 失活

Abstract: The selective dehydrogenation of ethanol to acetaldehyde is a promising route for acetaldehyde production. Although Cu-based catalysts exhibit high activity in ethanol dehydrogenation, a rapid deactivation due to Cu sintering always occurs. In this study, highly dispersed Cu species were stabilized using the silanol defects in Beta zeolite (denoted as Beta) resulting from dealumination, and applied as robust catalysts for ethanol-to-acetaldehyde conversion. Typically, a long catalyst lifetime of 100 h with an acetaldehyde yield of ~70% could be achieved over 5% Cu/Beta. The presence of Cu+ and Cu0 species and the agglomeration of Cu particles after a long-term reaction for 180 h were revealed by transmission electron microscopy, thermogravimetric analysis, and CO-diffuse-reflectance infrared Fourier transform spectroscopy, and were responsible for the deactivation of the Cu/Beta catalyst in the ethanol-to-acetaldehyde conversion.

Key words: Ethanol dehydrogenation, Acetaldehyde, Zeolite, Cu-based catalyst, Deactivation