第十六届国际催化会议在京召开
2016年7月3-8日在北京举办的第十六届国际催化会议，以催化与世界的可持续发展为主题，倡议全世界的催化领域学者前来北京进行学术交流，内容主要集中在催化科学和技术的关键作用，包含以下三个方面：1. 传统化石资源的清洁生产和高效利用；2. 可再生能源的发展；3. 减少和消除环境污染物，实现低碳经济。
此次会议覆盖催化的各个方面，包括能量催化、催化材料、催化机理、环境催化、工业催化、电催化、光催化、催化化学合成和生物质能转化等多方面，共有来自50多个国家的2500多人参加了此次会议。ICC是每四年举办一次的最负盛名的国际催化会议。
我校多名师生参与了此次催化界的盛会，学习和了解催化领域的前沿方向及最新动态。重点实验室主任张润铎教授受邀作题为“Co3O4 with different morphologies for catalytic combustion of CO and CH4: Investigation on the role of their diverse oxygen species by oxygen isotopic exchange technique”的学术报告。
张润铎教授在16th ICC会议作报告
报告内容简介：
Co3O4 with different morphologies for catalytic combustion of CO and CH4 and investigation the role of their diverse oxygen species with oxygen isotopic exchange reaction
PeixinLi, Runduo Zhang*, NingLiu, ShanshanLiu,
Beijing University of Chemical Technology, State Key Laboratory of Chemical Resource Engineering, 100029, Beijing, China
*corresponding author: zhangrd@mail.buct.edu.cn
1. Introduction
The compositions, intrinsic crystal structures, morphologies and microstructures of materials have great inference on physicochemical properties[1-3]. In this present work, four different morphology of Co3O4 have been obtained, namely nanoslice (NS), nanoparticle (NP), nanoflower (NF), and nanopolyhedron (NPL). Further, investigation was carried out to study the oxygen mobility using oxygen isotopic exchange reaction (OIE). The result obtained provided an insight about the oxidation mechanism over these materialsand elucidate the role of surface and bulk oxygen, observed to be different in the samples. To the best of our knowledge, there is dirt information about the involvement of OIE to explain catalytic activity with various morphologies for the catalytic combustion of CO and CH4.
2. Experimental
NS and NP samples were prepared by homogeneous precipitation method, NF sample was prepared by solvothermal synthesis, and NPL sample was prepared by direct decomposition method. The characterization information of the samples was investigated by XRD, N2adsorption/desorption, H2-TPR, and XPS. The measurement of oxygen exchange capacity was investigated by advanced oxygen isotopic exchange and equilibration techniques. CO and CH4 oxidation reaction was performed in a tubular microreactor. 200 mg of material was inserted inside the reactor. The reaction flow composed of 2 vol. % of CO or CH4, 20 vol. % of O2, and balanced by Ar with a total flow rate of 100 ml min−1 (corresponding to a space velocity of approximately 35,000 h-1). The reactor was regulated continuously using a temperature controller with a thermocouple inserted into the catalyst bed. The mixed gases were monitored usinggas chromatography (GC4000A) equipped with TCD.
3. Results and discussion
Fig. 1 Evolution of the number of exchanged oxygen atoms (Ne) and the exchange rate (Re) versus temperature of reaction over Co3O4
Co3O4-NS, Co3O4-NP, Co3O4-NF, and Co3O4-NPL samples were undertaken by performing the temperature programmed exchange reaction. Experiments have showed the cumulative number of oxygen atoms exchanged Ne and the evolution of the rate of exchange Re (Fig. 1). Obvious distinctions were observed within the temperature range for 18O2activation among the investigated materials. The total number of oxygen atoms exchanged at 600 oC is significantly different. The temperature of oxygen isotope exchange for NS, NP and NF samples started from 200 oC. Nevertheless, the temperature was initialized at 370 oC for NPL sample. In particular, NS sample showed the most amount of exchanged oxygen atom at any temperature.
Fig. 2 CO and CH4 conversion versus reaction temperature for ■:NS, ●:NP, ♦:NF, ▲:NN, ★:NPL
The CO oxidation and CH4 combustion is used to determine the activity of Co3O4 samples with diverse morphology. As shown in Fig.2, CO and CH4 conversion was improved with the increase of reaction temperature. From the experimental data, T10%, T50% and T90% can be obtained. NS sample has the best catalytic activity, and the T10%、T50% and T90% for CO oxidation is 30 oC, 35 oC, and 40 oC, respectively. CO can be initially converted even at room temperature. However, these values of NPL sample are 140 oC, 152 oC, and 172 oC, indicating the very obvious gap between NS and NPL samples. For CH4 combustion, the result showed similar patterns. It was clearly found the activity sequence is NS > NP > NF > NPL.
4. Conclusions
In the present investigation, four morphologically different nanostructures of Co3O4 were procured and all belong to pure spinel Co3O4(JCPDS card no. 43-1003). The NS sample mainly expose the high index (3 1 1) lattice plane which is conducive to improve oxygen exchange capacity during the CO oxidation and CH4 combustion reaction. The surface areas and redox abilities of these Co3O4 samples follow the order: NS > NP > NF > NPL. Furthermore, the NS sample also showed the best transfer ability for surface and bulk oxygen through oxygenisotopic exchange reaction. In the catalytic activity test, CO oxidation and CH4 combustion showed similar behavior, the NS sample shown the best activity for the two reaction systems and matched well with the result of isothermal oxygen isotopic equilibration reaction and isothermal oxygen exchange reaction, respectively.
References
1. Meng, B., Z. Zhao, X. Wang, J. Liang, and J. Qiu, Applied Catalysis B: Environmental, 2013 129: 491-500.
2. Chen, J.S., T. Zhu, Q.H. Hu, J. Gao, F. Su, S.Z. Qiao, and X.W. Lou, ACS Applied Materials & Interfaces, 2010. 2(12): 3628-3635.
3. Xie, X., Y. Li, Z.-Q. Liu, M. Haruta, and W. Shen, Nature, 2009. 458 (7239): 746-749.
