Measurement of exothermic reactions by differential scanning calorimetry

O'Neill, M.J.

doi:10.1021/ac60354a045

Cited by 19 publications

(6 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To make more robust predictions of experimental results under given experimental conditions, and eventually be able to deduce the experimental conditions from the results, we have created a simple mathematical model of the experiment. There is precedent for modeling differential scanning calorimetry experiments, including pioneering work, [24,25] theoretical studies, [26,27,28] reviews, [29,30] and computer simulations. [31,32] However, we have not found prior models in the literature that involve reactions with gas-phase species.…”

Section: General Approachmentioning

confidence: 99%

Metal hydride differential scanning calorimetry as an approach to compositional determination of mixtures of hydrogen isotopologues and helium

Robinson

Luo

Cai

et al. 2015

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

Gaseous mixtures of diatomic hydrogen isotopologues and helium are often encountered in the nuclear energy industry and in analytical chemistry. Compositions of stored mixtures can vary due to interactions with storage and handling materials. When tritium is present, it decays to form ions and helium -3, both of which can lead to further compositional variation. Monitoring of composition is typically achieved by mass spectrometry, a method that is bulky and energy-intensive. Mass spectrometers disperse sample material through vacuum pumps, which is especially troublesome if tritium is prese nt. Our ultimate goal is to create a compact, fast, low-power sensor that can determine composition with minimal gas consumption and waste generation, as a complement to mass spectrometry that can be instantiated more widely . We propose calorimetry of metal hydrides as an approach to this, due to the strong isotope effect on gas absorption, and demonstrate the sensitivity of measured heat flow to atomic composition of the gas. Peak shifts are discernible when mole fractions change by at least 1%. A mass flow restriction results in a unique dependence of the measurement on helium concentration. A mathematical model is presented as a first step toward prediction of the peak shapes and positions. The model includes a useful method to compute estimates of phase diagrams for palladium in the presence of arbitrary mixtures of hydrogen isotopologues. We expect that this approach can be used to deduce unknown atomic compositions from measured calorimetric data over a useful range of partial pressures of each component.If composition could be measured by a method that is more compact and lower power, without consuming or dispersing the sampled gas, it will be possible for a gas handling system to report composition at more sampling © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ bw fig2 bw fig3 bw fig4 bw fig5l bw fig5r bw fig6l bw fig6r bw fig7l bw fig7r bw fig8l bw fig8r bw fig9 bw fig10l bw fig10r bw fig11l bw fig11r bw fig12l bw fig12r bw fig13l bw fig13r bw figs1 bw figs2 baseline-h2.tif bw figs3 onset-vanthoff.tif bw figs4 curve baseline.tif bw figs5 const p vary h d.tif bw figs6bl sensitivity fix h add more d pct.tif bw figs6br sensitivity fix d add h pct.tif bw figs6tl sensitivity fix d add more h.tif bw figs6tr sensitivity fix h add d pct.tif bw figs7 ternary.tif

show abstract

Section: General Approachmentioning

confidence: 99%

Metal hydride differential scanning calorimetry as an approach to compositional determination of mixtures of hydrogen isotopologues and helium

Robinson

Luo

Cai

et al. 2015

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

show abstract

“…The manner in which thermal resistances manifest themselves in the morphology of a DSC thermogram perhaps is best treated in terms of electrical equivalent circuits (2, [5][6][7][8][9]. Figure 1 illustrates the equivalent circuit thát was used by us earlier (2) for a DSC cell of the heat-flux type.…”

Section: Model and Simulation Protocolmentioning

confidence: 99%

Computer simulation of differential scanning calorimetry: influence of thermal resistance factors and simplex optimization of peak resolution

Jang¹,

Rajeshwar²

1988

Anal. Chem.

View full text Add to dashboard Cite

Computer simulations of differential scanning calorimetry (DSC) are presented based on an electrical equivalent-circuit model. The Influence of variables Including heating rate, sample mass, and thermal resistance factors on the DSC peak shape, and associated peak parameters, was simulated. Melting was chosen as a test thermal transition for this purpose. The application of simplex optimization to the peak resolution problem In DSC Is described for the first time. This methodology Is Illustrated for two test cases involving the melting of a two-component mixture.Computer simulation offers a powerful route to testing the influence of parametric variables which are not easily amenable to experimental control by the analytical chemist. A case in point concerns thermal resistances in a differential scanning calorimetry (DSC) cell. The thermal resistances of the major heat-flow paths in a DSC cell are recognized to be crucial to the performance of this analytical technique (1); however, a systematic evaluation of their influence on DSC peak shapes presents many experimental problems. In a previous paper, an equivalent-circuit model was presented for a DSC cell of the heat-flux type (2). This model was subsequently utilized to guide the development of a DSC peak resolution-enhancement methodology based on the use of He as a purge gas (3). This paper details further refinement of this model, and its application to computer simulations of a DSC scan.In particular, the model and simulations were used to probe the influence of thermal resistances on peak area, amplitude, onset temperature, and resolution.A second objective of this study was to explore the applicability of the simplex optimization technique (4) to DSC. The simplex technique is applied, we believe, for the first time, to the optimization problem involving the resolution of overlapping DSC peaks. Overlapping DSC peaks are usually resolved by decreasing either the sample mass, the heating rate, or both. Obviously, selection of an optimal combination

show abstract

“…Crystallization processes are exothermic and produce a significant increase in sample temperature. Thus, unusual peak shapes that can be difficult to analyze depending on the heat flow associated with the crystallization process are commonly observed . These effects can be avoided using the SCTA methodology as a control of the reaction rate minimizes the heat transfer phenomena.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, unusual peak shapes that can be difficult to analyze depending on the heat flow associated with the crystallization process are commonly observed. 58 These effects can be avoided using the SCTA methodology as a control of the reaction rate minimizes the heat transfer phenomena. Moreover, it is well known that DSC baseline largely changes depending on the heating conditions because a change in specific heat often occurs after the sample goes through crystallization, which makes the integration of a peak which has a baseline shift difficult and less accurate.…”

Section: Introductionmentioning

confidence: 99%

A Promising approach to the kinetics of crystallization processes: The sample controlled thermal analysis

et al. 2016

View full text Add to dashboard Cite

Constant Rate Thermal Analysis (CRTA) method implies controlling the temperature in such a way that the reaction rate is maintained constant all over the process. This method allows determining simultaneously both the kinetic parameters and the kinetic model from a single experiment as the shape of the CRTA α‐T curves strongly depends on the kinetic model. CRTA method has been developed in the market only for thermogravimetric and thermodilatometric systems and, therefore, its use has been limited until now to the kinetic study of processes involving changes in mass or size of the samples, respectively. To overcome this obstacle, a method has been developed in this work for using the DSC signal for controlling the process rate in such a way that CRTA would be applied to the kinetic analysis of either phase transformations or crystallizations. The advantages of CRTA for performing the kinetics of crystallization processes have been here successfully demonstrated for the first time after selecting the crystallization of zirconia gel as test reaction.

show abstract

Measurement of exothermic reactions by differential scanning calorimetry

Abstract: limited results reported here with a particular stripping reaction scheme must await further study.

Cited by 19 publications

References 39 publications

Metal hydride differential scanning calorimetry as an approach to compositional determination of mixtures of hydrogen isotopologues and helium

Metal hydride differential scanning calorimetry as an approach to compositional determination of mixtures of hydrogen isotopologues and helium

Computer simulation of differential scanning calorimetry: influence of thermal resistance factors and simplex optimization of peak resolution

A Promising approach to the kinetics of crystallization processes: The sample controlled thermal analysis

Contact Info

Product

Resources

About