摘要
环己烷选择性氧化生成的环己醇和环己酮是己内酰胺合成中的重要中间体,在尼龙生产中具有重要作用,但工业路线条件苛刻,效率低。温和条件下环己烷选择性氧化引起极大关注,而光催化在低温环境压力下的饱和 C-H 活化和氧化具有独特优势。本文采用水热法制备了一系列 Bi_(2)O_(3)-TiO_(2)_(2)复合催化剂,对其结构、形貌、光学与光电化学性质通过多种方法包括 SEM、XRD、N吸脱附、UV-Vis、光致发光光谱、瞬态光电流响应等进行详细表征。在室温、0.1 MPa 氧气为氧化剂、500 W 氙灯模拟太阳光条件下比较了纯 TiO_(2)、BiO和 Bi_(2)O_(3)-TiO_(2)_(2)复合物对环己烷选择性氧化的催化性能,结果表明,复合 BiO后提高了 TiO_(2)的催化活性,其中 9%Bi_(2)O_(3)-TiO_(2)_(2)的活性最高,在反应条件下,转化率达 13.32%;环己酮/醇总选择性为 95.5%,其中环己酮的选择性为 57.3%、环己醇的选择性为 38.2%、酮醇比为 1.5。表征结果证实复合催化剂具有更宽的光吸收频率范围,能有效促进光生电子-空穴分离;同时,比表面积表征也表明复合催化剂比表面积比 TiO_(2)和BiO更高,有利于增加表面活性中心浓度。
The selective oxidation of cyclohexane to cyclohexanol and cyclohexanone is an important process to synthesis of caprolactam, which is an important raw material in the production of nylon. However, the industrial route suffered from the disadvantages such as harsh reaction conditions and low reactivity, therefore, selective oxidation of cyclohexane under mild conditions attracted great attention. Since photocatalysis has unique advantages in saturated C-H activation and oxidation, in this paper, a series of Bi_(2)O_(3)-TiO_(2)_(2)composite photocatalysts were prepared by hydrothermal method. Their structure, morphology, optical and photoelectrochemical properties were characterized in detail by various techniques such as SEM, XRD, Nphysical absorptionn and desorption, UV-Vis,photoluminescence spectroscopy, and transient photocurrent response. The photocatalytic performance of pure TiO_(2), BiOand Bi_(2)O_(3)-TiO_(2)_(2)composites toward selective oxidation of cyclohexane was compared under the reacTiO_(2)n conditions of ambient temperature, 0.1 MPa of oxygen, and 500 W xenon lamp simulating solar light source. The results show that the catalytic activities of hybrid Bi_(2)O_(3)-TiO_(2)_(2)composites are higher than that of pure TiO_(2). Among them, 9%Bi_(2)O_(3)-TiO_(2)_(2)exhibits the highest activity, the conversion is 13.32%, and the total selectivity(cyclohexanone and cyclohexanol) is 95.5%. The selectivity of cyclohexanone and cyclohexanol is 57.3% and 38.2%, respectively, and the ketone to alcohol ration is 1.5. The characterization results confirm that the composite catalyst has a wider light absorption frequency range and can effectively promote the separation of photogenerated electrons and holes. In addition, the Bi_(2)O_(3)-TiO_(2)_(2)composites possess higher specific surface area than pure TiO_(2), which is conducive to increasing the concentration of surface active centers.
作者
郑小强
佟占鑫
吴健博
廖诗艺
王海鹏
陈丽娟
ZHENG Xiaoqiang;TONG Zhanxin;WU Jianbo;LIAO Shiyi;WANG Haipeng;CHEN Lijuan(School of Materials Science and Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Key Laboratory of Advanced Materials for New Energy Storage and Conversion,Xiangtan 411201,China)
出处
《复合材料学报》
EI
CAS
CSCD
北大核心
2022年第7期3262-3270,共9页
Acta Materiae Compositae Sinica
基金
国家自然科学基金(21406058)
湖南省自然科学基金(2021JJ30237)。
