Thermal decomposition kinetic research on hydroxylamine inorganic salts and organic deriavatives
摘要
Hydroxylamine compounds are widely used due to their high reactivity, but high reactivity usually also means high instability. In recent years, two fatal accidents involving decomposition and explosion of organic hydroxylamine derivatives had been reported. This article investigated the thermal stability and decomposition kinetics of the organic hydroxylamine derivatives o-(3-chloro-2-propenyl)-hydroxylamine and clethodim, which were the protagonists in the accident, as well as three hydroxylamine inorganic salts: hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine-O-sulfonic acid. Starting decomposition temperature (Tleft) of the o-(3-chloro-2-propenyl)-hydroxylamine and clethodim was 82–115 °C and 99–128 °C respectively in different heating rates, and average specific heat were 2663 J g−1 and 1022 J g−1, respectively. The decomposition process of both was multistep reactions and AKTS decoupling and peak separation showed they were four-step reactions. For o-(3-chloro-2-propenyl)-hydroxylamine, two steps were more in line with autocatalytic kinetic, and the other two steps belong to n-order. Four steps of clethodim all belong to n-order reaction. Decomposition steps of hydroxylamine inorganic salts were relatively less, but usually accompanied with melting, making it difficult to determine the starting temperature. DSC research results indicated that Tleft of the three salts were 165 °C, 157 °C and 48 °C, and 135 °C respectively in gold-plated crucible, which were higher than former researchers’ results; the reason was investigated in this article. Tleft of hydroxylamine hydrochloride aqueous solution was lower than its solid, which may due to the catalytic effect of free ions in aqueous solutions on their thermal decomposition.