Degradation Kinetics and Solvent Effects of Various Long-Chain Quaternary Ammonium Salts

Abstract

<div>Surfactants such as quaternary ammonium salts (QAS) have been in increasing demand, for emerging new applications. Recent attempts at process intensification of</div><div>their production, have disclosed the need for a better understanding of QAS thermal stability. This work aims to determine degradation kinetics of various QASs, and the</div><div>associated solvent effects. Degradation kinetics of four methyl carbonate QASs were determined in various</div><div>polar solvents in stainless steel batch autoclaves. <sup>1</sup>H NMR spectrometry was employed for online analysis of the reaction mixtures. The kinetic parameters were then used</div><div>to compare the thermal stability of the four compounds in the polar solvents. Water showed not degradation, and methanol (MeOH) was the solvent that provided the</div><div>second-best stability. Water-MeOH mixtures may provide an overall optimum. More, and longer long-chain substituents increased the degradation rate. Thermogravimetric Analysis was used to obtain the thermal stability in a solid-</div><div>state, i.e. solventless environment. Isoconversional analysis showed that no reliable kinetic parameters could be determined. Nevertheless, the data did allow for a compar-</div><div>ison of the thermal stability of 14 different QASs. Furthermore, the relative instability of the compounds in solid-state demonstrated the challenges of solventless QAS production.</div>

Renewable dimethyl carbonate for tertiary amine quaternisation: kinetic measurements and process optimisation

“…This study included a numerical verification, as well as experimental work. For the numerical characterisation, Reynolds and Péclet dimensionless numbers were used, as shown in eqn ( 6) and (7), where u and d represent the superficial velocity through, and the inner diameter of the tube, correspondingly.…”

“…For the degradation reaction, Arrhenius parameters from previous work were used. 7 For the validation of the model, the input parameters were matched with the operating conditions. The flow rate was set between 0.05 and 1.60 mL min −1 , and the temperature was set between 130 and 160°C.…”

“…At higher temperatures, QASs are (depending on their configuration and anion) increasingly susceptible for decomposing according to Hofmann elimination. 7 In the Menshutkin reaction, a tertiary amine reacts with an alkyl halide (predominately methyl chloride), as shown in Fig. 1.…”