Zero-Order Versus Intrinsic Kinetics for the Determination of the Time to Maximum Rate under Adiabatic Conditions (TMR_ad): Application to the Decomposition of Hydrogen Peroxide

Abstract

The thermal safety of chemical processes requires knowledge of the safety parameters that quantify the probability, such as time to maximum rate under adiabatic conditions (TMR ad ), and the severity, such as adiabatic temperature rise under adiabatic conditions (ΔT ad ). The zero-order approximation is used to ease the determination of TMR ad values at different process temperatures; but how can one be sure that this approximation is acceptable, compared to the use of an intrinsic kinetic model? In the literature, there are no such studies that compare the values of TMR ad by using zero-order and intrinsic kinetic models. For that, decomposition of hydrogen peroxide in the presence (and in the absence) of copper sulfate was studied in an advanced reactive system screening tool (ARSST) unit. This calorimeter operates under near-adiabatic conditions, based on heat loss compensation principle, and by using a background heating rate (β). In a first stage, a kinetic model was built to estimate the intrinsic kinetic constants. Then, a comparison between the values of TMR ad from the zero-order and the intrinsic kinetic model was performed. It was found that the difference of TMR ad values obtained by these two models can be significant. The influence of β and reactant concentrations were found to play an important role in this difference. As good practice, in the case of missing kinetic and thermodynamic data, a user should test different background heating rates to verify their influence on TMR ad values obtained from the zero-order model.

Thermal Risk Analysis Based on Reaction Mechanism: Application to the 2,6-Diaminopyrazine-1-oxide Synthesis Process

“…The correlation coefficient R in Figure is higher than 0.99, which proves the validation of the simulated results. On the basis of the above kinetic analysis results, we then predicted the trend of TMR ad , − as shown in Figure . From Figure , one can directly read that T D24 , which is the temperature corresponding to TMR ad for 24 h, is equal to 31.1 °C.…”

Thermal Risk Assessment of Levulinic Acid Hydrogenation to γ-Valerolactone

“…The heat flow rate q rx due to the chemical exothermic reactions can be expressed as The determination of β, which is the background heating rate, was explained in the previous articles of our group. 42,45 This parameter was fixed for each experiment (Table 4).…”

“…The benefit of such an approach is to be able to determine the safety parameters at different operating conditions which is not possible by using a zero-order approach. 42 At last, a risk matrix based on severity and probability of thermal risk was created for thermal risk assessment at different reaction conditions including levulinic acid concentration, temperature, catalyst loading, and hydrogen pressure.…”

Parameters affecting thermal risk through a kinetic model under adiabatic condition: Application to liquid-liquid reaction system

“…It yields critical experimental knowledge of the rates of temperature and pressure rise during a runaway reaction. The detailed description of the ARSST equipment can be found in our previous articles [42,49].…”

“…This work proposes to fill this gap by building a kinetic model for the epoxidation of cottonseed oil by peracetic acid produced in situ. The benefit of such model compared to the zero-order approach [49] is that one can estimate the safety parameters at different initial operating conditions.…”