会议名称：The 10th International Conference on Environmental Catalysis

会议时间：2018.9.22-2018.9.26

报告题目：Zeolitic catalysis on air pollution control across microscopic structure, mesocopic behavior, and macroscopic performance

张润铎教授大会风采展示

摘要：

Zeolitic catalysis on air pollution control across microscopic structure, mesocopic behavior, and macroscopic performance

Runduo Zhang*

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029 P. R. China

* zhangrd@mail.buct.edu.cn  Tel：86-10-64412054

Catalytic purification of series of pollutants with various N valences, including nitric oxides (NO_x), nitrous oxide (N₂O), and nitriles (HCN, CH₃CN, and C₂H₃CN), which can cause some serious environmental problems, such as acid rain, haze weather, global warming, and even death, becomes urgent and necessary. The zeolite catalysts with high internal surface areas, uniform pore systems, considerable ion-exchange capabilities, and satisfactory thermal stabilities are herein addressed for the corresponding depollution processes. The important physicochemical properties of zeolite catalysts, including shape selectivity, surface area, acidity, and redox ability, are described in detail. The catalytic behaviors as well as mechanism studies based on spectroscopic and kinetic approaches and molecular simulations are conducted. Emphasis is placed on the structure-performance relationship with an aim to design an ideal zeolite-based catalyst for the effective elimination of harmful N-containing compounds.

1. NH₃-SCR has become one of the most promising deNO_x methods under lean conditions. However, due to some drawbacks for the commercialized V-W-Ti catalysts, more attention is now paid to the development of new superiorly active materials for NO_x removal. The topology effect of diverse zeolites on the corresponding SCR performances was investigated. A clear trend was observed that the NH₃-SCR performance was gradually improved with the zeolite-framework structures changing from straight-channel (ZSM-5, Beta, Y) to cage-type (SSZ-13, SSZ-16, SSZ-17), bridged by hybrid-structures (OFF-ERI series: Offretite, ZSM-34, UZM-12). Cu-SSZ-13 zeolite was recently proposed to exhibit extremely high low-temperature activity and N₂ selectivity. The utilization of the very expensive and toxic template of N, N, N trimethyl-1-adamantylammonium hydroxide (TMA-daOH) for Cu-SSZ-13 synthesis leads to a significant increase of the catalyst cost, which seriously prevents the industrial realization. Therefore, an economical way to synthesize SSZ-13 by utilizing a cheap template of (Choline Chloride) has become important directions for the NH₃-SCR technique. In addition, the concept of “quasi shape selectivity” illustrated for SSZ-13 is taken into account for the NH₃-SCR study to obtain a common principle for the design of highly efficient zeolite catalysts. In addition, the morphology control of zeolite was verified to be crucial. Cu-ZSM-5 zeolites with morphologies of particle, sheet, and hollow-sphere were synthesized successfully which show activities extremely superior to that of the commercial Cu-ZSM-5 prepared by traditional method. Furthermore, the adsorption and mass transfer behaviors over Cu-ZSM-5 during SCR process was calculated based on GCMC and MD methods for designing catalyst with ideal overall performances.

2. A large and increasing amount of N₂O is generated from the chemical industries for the production of adipic acid and nitric acid. N₂O emission control has therefore become one of the great challenges for environmental protection. Initially, N₂O direct decomposition over Fe-BEA zeolite prepared by wet ion-exchange (WIE) was investigated based on the experimental and theoretical studies. Two kinds of reaction mechanism, with respective formation of oxygen (O₂) or nitrogen oxide (NO_x) intermediate, for the direct decomposition of N₂O over Fe-beta zeolite were proposed according to N₂O-TPD and in-situ DRIFTS investigation and density functional theory (DFT) study.

3. With the financial support of Nation high-technique project, high efficient catalyst of Cu-ZSM-5 with an ideal selectivity of CN^-→N₂ was found and thereafter applied for the purification of highly toxic nitrile gases. The construction of a fine zeolite power into a honeycomb monolith is necessary for industrial applications. The cracking problem due to the high thermal sensitivity of the porous zeolite substrate was well solved by adding binder and carefully controlling the dry speed and atmosphere.

Reference

[1]      R. Zhang, N. Liu, Z. Lei, B. Chen*, Chem. Rev., 2016, 116: 3658-3721.

[2]      R. Zhang* et al., J. Catal., 2012, 294: 99-112; 2012, 295: 45-58; 2010, 272: 210-219.

[3]      R. Zhang* et al., Environ. Sci. Technol., 2014, 45: 13909-13916; 2012, 46: 11280-11288.

[4]      R. Zhang* et al., Appl. Catal. B., 2014, 146: 79-93; 2014, 146: 94-104.