Determination of reactivity and ignition behaviour of solid fuels based on combustion experiments under static and continuous flow conditions

The reactivity and ignition behaviour of solid fuels is a major parameter for combustion and gasification processes, but also for a safe transport and storage of pyrophoric solids. In this work, seven non-isothermal methods were compared with respect to characterise the ignition behaviour as well as to calculate kinetic parameters; for comparison also ‘classical’ isothermal measurements were done. Different methods and reactors (fixed and fluidised bed, thermogravimetry, oven heating tests) were used and tested under static and continuous flow conditions, taking charcoal, activated carbon and blast furnace coke as model solid fuels. The accuracy of all tested methods to determine kinetic data is reliable within a range of confidence of about ±50 K (with respect to the temperature needed to reach a certain level of reactivity). For a fast and relative simple determination of kinetic data, the ignition test in a small lab-scale fixed bed reactor can be recommended. Additional calculations show that the critical parameters with respect to ignition during transport and storage can also be calculated quite accurately based on this method, i.e. no elaborated basket heating tests are needed.     

Microscopic magnetism in lithium insertion materials of LiNi1−xCoxO2 (x = 0, 1/4, 1/2, 3/4, and 1)

The magnetic nature of lithium insertion materials of LiNi_1−xCo_xO₂ (x = 0, 1/4, 1/2, 3/4, and 1) were investigated by means of positive muon-spin rotation/relaxation (μ⁺SR) spectroscopy combined with X-ray diffraction (XRD) analyses and susceptibility measurements. Zero field μ⁺SR spectra for all the samples below 300 K were well fitted by a dynamic Kubo–Toyabe function, indicating the existence of randomly oriented magnetic moments even at 2 K, i.e., disordered state. The field distribution width Δ due to magnetic Ni³⁺ ions decreases exponentially with increasing x, suggesting that the Co substitution is likely to simply dilute Ni moments. This also supports that cobalt and nickel ions are homogeneously distributed in a solid matrix even in a muon-scale (microscopically), which is consistent with the results of macroscopic measurements.     

Choosing a reprocessing technology requires focusing on what we value

“Technology decisions for reprocessing must take into account technology and policy decisions for the entire fuel cycle” – Chairwoman Biggert before the House Committee on Science, Subcommittee on Energy. How will these decisions be enabled to take both technology and policy into account? This paper presents a set of alternatives for selecting a Light Water Reactor legacy fuel reprocessing technology for the United States based on policy values and technological attributes. Seven example policy value scenarios are modeled showing how dependent technology selection is to values. While four of the scenarios result in the COEX process being selected, the results demonstrate that different technologies could be selected with changes in policy values.     

Solid Catalyst with Ionic Liquid Layer (SCILL) – A New Concept to Improve Selectivity Illustrated by Hydrogenation of Cyclooctadiene

A new concept of a solid catalyst with ionic liquid layer (SCILL) as a novel method to improve the selectivity of heterogeneous catalysts is presented. The sequential hydrogenation of cyclooctadiene (COD) to cyclooctene (COE) and cyclooctane on a commercial Ni catalyst coated with the ionic liquid [BMIM][n‐C₈H₁₇OSO₃] was tested as first model system. Compared to the original catalyst, the coating of the internal surface with the ionic liquid (IL) strongly enhances the maximum intrinsic COE yield from 40 to 70 %. This effect is already achieved for a pore filling degree of only 10 % and cannot be explained by pore diffusion, as shown by experiments with different particle sizes and theoretical considerations. The IL layer is very robust and no leaching into the organic phase was detectable.     

MALDI‐TOF MS characterization of proanthocyanidins from cranberry fruit (Vaccinium macrocarpon) that inhibit tumor cell growth and matrix metalloproteinase expression in vitro

Proanthocyanidin‐rich extracts were prepared by fractionation of the fruit of the North American cranberry (Vaccinium macrocarpon). In vitro growth inhibition assays in eight tumor cell lines showed that selected fractions inhibited the growth of H460 lung tumors, HT‐29 colon and K562 leukemia cells at GI₅₀ values ranging from 20 to 80 µg ml^?1. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) of one of these fractions found it to be composed of polyflavan‐3‐ols, which are primarily tetramers through heptamers of epicatechin containing one or two A‐type linkages. Whole cranberry extract and the proanthocyanidin fractions were screened for effect on the expression of matrix metalloproteinases in DU 145 prostate carcinoma cells. The expression of MMP‐2 and MMP‐9 was inhibited in response to whole cranberry extract and to a lesser degree by the proanthocyanidin fractions. Copyright © 2005 Society of Chemical Industry     

Applying Topological and Economical Principles in Catalyst Design: New Alumina–Cobalt Core–Shell Catalysts

Designing new and effective catalysts may be an art, but its consequences are very real and pragmatic. That said, chemists often build designs on ideal systems, whereas the manufacturing of chemicals requires catalysts that withstand varied feeds, harsh conditions and long exposure times. Moreover, economical considerations are often underestimated at the catalyst design stage. Here we discuss the inclusion of economical and topological considerations early on in the catalyst design process, giving as an example the synthesis and testing of a new type of alumina/cobalt Fischer–Tropsch catalysts.

     

Aqueous and Mineral Intrinsic Bioremediation Assessment: Natural Attenuation

An approach to evaluating intrinsic bioremediation, aqueous and mineral intrinsic biodegradation assessment (AMIBA) is described. AMIBA is based on the microbial reduction of Fe3+ and SO42?, forming reduced Fe and S mineral species in amounts stoichiometrically equivalent to the contaminant mass oxidized by microbial processes. Mineral data from sediment cores are emphasized rather than the aqueous data used in existing protocols. AMIBA was demonstrated at Westover Air Force Base, Chicopee, Massachusetts. Over 300 times more reduced Fe2+ was in mineral form, compared to aqueous. The distribution of mineral Fe3+ and Fe2+ marked the historic extent of the plume, confirming plume retreat. Aqueous SO42? reduction resulted in the deposition of equivalent amounts of iron sulfide minerals near the source area. The total mass of fuel degraded by intrinsic bioremediation and the rate of source depletion was estimated. Thus, the past and future performance of intrinsic bioremediation was assessed using one sampling event rather than relying on protracted monitoring, as is the current practice.