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[交流]
密歇根大学美国工程院院士Ralph T Yang诚招CSC 访问学者或者联合培养博士已有1人参与
请感兴趣的CSC同学或者访学老师直接发邮件给杨教授,yang@umich.edu
课题组链接:https://che.engin.umich.edu/people/ralph-yang/
以下是课题组介绍:
Research Interests: ^top
Adsorption. This research is focused on gas adsorption for the purpose of separation and purification. All fundamental aspects of adsorption are being studied: 1) Gas-solid equilibria, 2) Diffusion (pore diffusion, surface diffusion, diffusion in zeolites), 3) Dynamics in fixed-bed adsorbers, 4) Cyclic adsorption/desorption processes with particular interest in pressure swing adsorption, and 5) the hysteresis phenomena. We are also exploring field-assisted adsorption and desorption. We have had success in ultrasound assisted desorption of strongly adsorbed molecules, such as phenols, on activated carbon and resins. We have found that ultrasound could replace chemical regeneration.
New Adsorbent Materials. We are exploring the possibility of synthesizing new sorbents by exploiting weak and reversible chemical bonds, such as pi-complexation. The pi-complexion is used for olefin-paraffin separations, e.g., diene/olefin and aromatic/aliphatic separations. and other difficult hydrocarbon separations. Immobilized cyanocobaltates are being developed for O2-selective adsorption. Zeolites containing mixed cations including Ag are being studied as superior N2-selective sorbents. An understanding for the bonding as well as design of the sorbents is being obtained through molecular orbital calculations. A methodology has been developed for sorbent design by applying Molecular Orbital (MO) theory. From MO calculations, for any given targeted adsorbate, we can quickly determine the best cation and anion to be placed on the surface.
We are developing new sorbent materials which are tailored to provide desired diffusivities for different gas molecules. With these sorbents, it will be possible to accomplish separations of gas mixtures by kinetic separation. Pillared clay is one of these materials that is being studied. Amines grafted on silica or MCM-48 are being explored as sorbents for acid gases. This is our first attempt to replace solvent extraction with dry adsorption by taking the approach of immobilizing extractants on solid substrates.
We have been studying new sorbents for the purpose of removing sulfur compounds from gasoline and diesel fuels. The current level of sulfur in gasoline and diesel is about 350 ppm, which must be lowered to below 30 ppm for gasoline and 15 ppm for diesel in 2006 under the federal law. Adsorption appears to be the most economical way (and possibly the only feasible way) to accomplish this difficult task. We have already shown that our pi-complexation sorbents are substantially better than all commercially available sorbents for the adsorption of low concentrations of thiophene from benzene. A major effort in developing this type of sorbents is on-going in our laboratory.
For hydrogen storage materials our approach is to use hydrogen spillover via an added catalyst in nanostructured carbons. We are working on sorbents that will meet the DOE target of 6.5% wt% storage at room temperature, and also to obtain a basic understanding of the hydrogen spillover mechanism.
Environmental Catalysis. The selective catalytic reduction (SCR) of NO with ammonia is a process that has been commercialized in the U.S. for power plant emission control. We are studying new catalysts for this reaction. We have had success with pillared clays and ion-exchanged pillared clays for these applications. The Fe(3+) and Cu(2+) ion-exchanged pillared clays are particularly active for these reactions. A U.S. patent has been granted for this work. Other active new catalysts for this reaction developed in our laboratory are: Fe-ZSM-5 and Fe-MOR.
We have been developing catalysts for low temperature SCR as well as that for low temperature selective catalytic oxidation of ammonia. Most active catalysts have been developed for both applications.
Gas-Carbon Reactions. Research is being conducted on the kinetics and mechanisms of gas-carbon reactions, both uncatalyzed and catalyzed. These reactions are important in coal conversion, metallurgy, catalyst regeneration, and a number of chemical processes. We are focusing on the C-NO reaction which is of importance in environmental control. Our approach has been to study rates on well defined active sites of carbon using single crystal graphite. We have been using MO theory to understand the mechanisms of the gas-carbon reactions. A new surface oxygen intermediate was proposed with which a unified mechanism can be applied to all gas-carbon reactions involving oxygen atoms.
Carbon Nanotubes and Hydrogen Storage. We are studying carbon nanotubes and graphite nanofibers (GNF) as unique sorbents. We have already found that multiwall nanotubes are the best selective sorbents for dioxins and also for NO. We are sorting out the controversies on issues of hydrogen storage in carbon nanotubes. We are also developing new nanomaterials for hydrogen storage by a spillover mechanism. |
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