Daniel Tondeur

Bio: Daniel Tondeur is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Pressure swing adsorption & Adsorption. The author has an hindex of 28, co-authored 104 publications receiving 2510 citations. Previous affiliations of Daniel Tondeur include Nancy-Université & Elf Aquitaine.

Unifying concepts in non-linear unsteady processes part II: Multicomponent waves, competition and diffusion

Abstract: The travelling wave approach to some unsteady transfer processes, developed for ‘one-component’ systems in Part I ( Chem. Eng. Process., 21 (1987) 167–178), is generalized to multicomponent systems, with particular concern for adsorption, electrophoresis, and diffusion. For systems in which a given order of ‘mobility’ or ‘competitiveness’ of the components exists, the multicomponent waves obey a set of relatively simple and general qualitative rules of behaviour. These rules govern, in particular, the number of distinct waves generated by a step perturbation, the concentration changes of the components relative to one another in each wave, and the spreading or sharpening tendency of these waves. This ‘competitive’ behaviour is shown to be related to the structure of the matrix coupling the conservation equations of the components, and especially to the orientation of its eigenvectors in the space of concentrations. On the basis of this analysis, a profound mathematical and also physical analogy is shown between fixed-bed Langmuir adsorption, electrophoresis with constant relative mobility, and Stefan-Maxwell diffusion. It is conjectured that, beyond the special form of the equilibrium or transfer laws considered above, the same qualitative trends should hold for all systems where several species compete for a limited resource or space, according to a definite hierarchy, a given order of competitiveness.

Redistribution of adsorbed VOCs in activated carbon under electrothermal desorption

Abstract: Electrothermal desolption is an electricity-promoted desolption technology developed only in the last decade It is extremely eficient and straightforward when the adsorbent is electrically conductive, since heating can be achieved by the Joule effect The volatile organic compound (VOC) vapors desorbing from micropores might redistribute and condense in mesopores with high concentration, which is possible since no dilution occurs To study this problem, benzene and activated carbon were used as the working system, and a theoretical analysis was developed In a wide temperature range up to 400°C, no VOC vapor could be condensed in mesopores with the strong micropore adsorption effect With the weak micropore adsorption effect, however, mesopore condensation will occur, but it only takes place in mesopores smaller than 3 nm in diameter, and the amount is generally negligible To prevent any possible condensation, the desorption temperature should at least equal the liquid boiling point calculated in a 2-nm capillary tube

Reversibility and performances in productive chromatography

Abstract: Irreversibilities in industrial chromatographic processes imply dissipation of free enthalpy in the form of dilution of the products by the eluent. It is shown that an important source of entropy is related to the propagation in the column of sharp concentration fronts of large amplitude (shocks). Some unconventional chromatographic modes are presented (two-way chromatography, segmented recycle chromatography) which reduce this particular source of entropy, and thus reduce the eluent consumption required to reach a given product purity. The performances of these modes are compared with those of the two conventional operating modes (classical single-pass chromatography, and chromatography with intermediate cut and recycle). The analysis is illustrated by experiments on the separation of K + and Na + cations with H + as eluent on a sulfonic ionic exchanger bed.

Entropy generation minimization: The new thermodynamics of finite-size devices and finite-time processes

Abstract: Entropy generation minimization (finite time thermodynamics, or thermodynamic optimization) is the method that combines into simple models the most basic concepts of heat transfer, fluid mechanics, and thermodynamics. These simple models are used in the optimization of real (irreversible) devices and processes, subject to finite‐size and finite‐time constraints. The review traces the development and adoption of the method in several sectors of mainstream thermal engineering and science: cryogenics, heat transfer, education, storage systems, solar power plants, nuclear and fossil power plants, and refrigerators. Emphasis is placed on the fundamental and technological importance of the optimization method and its results, the pedagogical merits of the method, and the chronological development of the field.

Adsorbents: Fundamentals and Applications

Abstract: Preface. 1. Introductory Remarks. 2. Fundamental Factors for Designing Adsorbent. 3. Sorbent Selection: Equilibrium Isotherms, Diffusion, Cyclic Processes, and Sorbent Selection Criteria. 4. Pore Size Distribution. 5. Activated Carbon. 6. Silica Gel, MCM, and Activated Alumina. 7. Zeolites and Molecular Sieves. 8. &pi -Complexation Sorbents and Applications. 9. Carbon Nanotubes, Pillared Clays, and Polymeric Resins. 10. Sorbents for Applications. Author Index. Subject Index.

Pressure swing adsorption

Abstract: A pressure swing adsorption cycle comprised of blowdown, purge, pressurization, feed, pressure equalization and rinse steps provided recovery from an atmospheric air feed, essentially dry and free of carbon dioxide, of a high yield of high purity nitrogen gas and a high yield of a product gas rich in oxygen as well as recovery of a residual feed byproduct gas for recycle with the air feed.

Methane storage in flexible metal–organic frameworks with intrinsic thermal management

Abstract: Two flexible metal-organic frameworks are presented as solid adsorbents for methane that undergo reversible phase transitions at specific methane pressures, enabling greater storage capacities of usable methane than have been achieved previously, while also providing internal heat management of the system. Natural gas — methane — is a clean and cheap fuel but its usefulness in transport applications is limited by storage problems, given its low energy density per unit volume under ambient conditions compared with petrol or diesel. One way of increasing methane storage capacity is to use tanks containing porous materials, such as metal–organic frameworks, as a storage medium. However, for every methane molecule adsorbed and desorbed there is an associated thermal fluctuation that could cause overheating or reduce storage efficiency if left unchecked. Here Jeffrey Long and colleagues describe two flexible metal–organic frameworks that undergo reversible phase transitions at specific methane pressures, enabling greater storage capacities of usable methane than have been achieved previously, while also providing internal heat management of the system. As a cleaner, cheaper, and more globally evenly distributed fuel, natural gas has considerable environmental, economic, and political advantages over petroleum as a source of energy for the transportation sector1,2. Despite these benefits, its low volumetric energy density at ambient temperature and pressure presents substantial challenges, particularly for light-duty vehicles with little space available for on-board fuel storage3. Adsorbed natural gas systems have the potential to store high densities of methane (CH4, the principal component of natural gas) within a porous material at ambient temperature and moderate pressures4. Although activated carbons, zeolites, and metal–organic frameworks have been investigated extensively for CH4 storage5,6,7,8, there are practical challenges involved in designing systems with high capacities and in managing the thermal fluctuations associated with adsorbing and desorbing gas from the adsorbent. Here, we use a reversible phase transition in a metal–organic framework to maximize the deliverable capacity of CH4 while also providing internal heat management during adsorption and desorption. In particular, the flexible compounds Fe(bdp) and Co(bdp) (bdp2− = 1,4-benzenedipyrazolate) are shown to undergo a structural phase transition in response to specific CH4 pressures, resulting in adsorption and desorption isotherms that feature a sharp ‘step’. Such behaviour enables greater storage capacities than have been achieved for classical adsorbents9, while also reducing the amount of heat released during adsorption and the impact of cooling during desorption. The pressure and energy associated with the phase transition can be tuned either chemically or by application of mechanical pressure.