Non-equilibrium thermodynamics |
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Physical chemistry seminars
The physical chemistry seminar is organized to get an overview of recent activity
in physics, chemistry, engineering areas in NTNU and collaborating institutions.
The speakers are the local and guest professors as well as
the students from the Physical Chemistry group at the Department of Chemistry, NTNU.
Schedule for Autumn 2011
| When: | Tuesdays, 14:15-15:00 |
| Where: | Onsager room, D3-114, Realfagbygget |
| 15 November, 14:15, D3-114 |
| Prof. De Chen, Department of Chemical Engineering, NTNU |
| First Principles Assisted Rational Design of Catalysts |
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Over the past decades, precise control of the catalytic properties of nanoparticles, either by modifying their compositions or by tailoring their sizes and shapes, has been one of the major research topics in catalysis studies. Sophisticated integration between the first principles and the experimental kinetic analysis has made kinetic modeling more predictive. The macroscopic behaviors such as activity, selectivity, and stability can be predicted from the configurations and energies of adsorptions and the activation barriers of elementary steps in the kinetic modeling. These microscopic properties can be accurately predicted from the surface composition and structure by using the first principles calculation. Rational catalyst design thus becomes possible to optimize the targeted macroscopic kinetic behaviors by structure-directing manipulation of the catalyst surface. This lecture focus on the kinetic analysis of the relationship between the catalyst properties (such as d-bond center and C, H and N binding energies) and the kinetic behaviors by means of highly integrated density functional theory and experimental investigation, with propane dehydrogenation and ammonia decomposition as probe reactions.
DFT calculation and isotopic trace kinetic study have suggested that the first C-H bond cleavage in propane is the rate determine step on all kind of Pt facets, either clean or carbon coated surfaces. The activity of C-H bond activation on different facets of Pt follows an order of Pt(211)>Pt(100)>Pt(111), and the same order holds for propene desorption energy and C-C bond activation. Pt(111) has been identified to have the best propene yield and stability due to the reduced coking potential by lowering the propene adsorption strength. As a result of rational catalyst design, octahedron Pt nanoparticles with dominating Pt(111) surface have been synthesized, which improves significantly the propane dehydrogenation selectivity and stability. In ammonia decomposition, DFT has predicted that the subsurface carbon under the Fe (111) and Fe (211) lowers N adsorption strength and thus lowers the energy barrier of ammonia decomposition. A graphene mediated catalyst is therefore developed by rational catalyst design. The subsurface graphene layer induces surface reconstruction of the Fe catalysts resulting in a preferential orientation of the active Fe(111) and Fe (211) planes, and the subsurface carbon increases further the activity as a result of lowering N adsorption strength.
Results clearly illustrate that, based on highly integrated DFT and experimental investigation, rational design of the catalysts to match the microscopic properties required by a reaction could lead to development of new catalysts or significant improvement of existing industrial catalysts.
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| 8 December, 13:15, Radsalen |
| PhD thesis defence: Leen van deer Ham, Department of Chemistry, NTNU |
| Improving the Second law efficiency of a cryogenic air separation unit |
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Previous seminars
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