Effects of heating rate, temperature and iron catalysis on the thermal behaviour and decomposition of 2-nitrobenzoyl chloride.
Runaway reactions arising from the decomposition of thermally unstable materials are a concern in industry due to the potentially devastating effects that they yield. Studies into the occurrence of thermal runaway incidents have shown the most likely cause to be a result of an inadequate investigation of the process prior to its operation on a large-scale. The chlorination of ortho-nitrated carboxylic acids is an industrially important reaction in the fine and agrochemical industries. The products of these reactions, ortho-nitrated acid chlorides, have been involved in runaway incidents that have resulted in violent explosions; hence, their thermal stability must be studied. Previous studies [S.D. Lever, M. Papadaki, Study of condition-dependent decomposition reactions: the thermal behaviour and decomposition of 2-nitrobenzoyl chloride, Part I, J. Hazard. Mater. 115 (2004) 91-100] showed that the decomposition of the parent molecule, 2-nitrobenzoyl chloride, is highly condition-dependent with the sample heating rate and temperature of decomposition playing a preponderant role in the course of the decomposition. Here, we present the results of studies of the decomposition of 2-nitrobenzoyl chloride, when the sample is subjected to various heating treatments, temperatures and in the presence of iron. As the temperature of decomposition was increased from 150 to 162 degrees C, the heat of decomposition was reduced from -215 to -90 kJ/mol. As the heat up rate applied in bringing the sample to the decomposition temperature increased, the heat of decomposition also increased. An increase in the heat up rate from 2 to 7.5 degrees C/min resulted in an increase in the heat of decomposition from -90 to -215 kJ/mol. The presence of iron and silver was observed to lower the heat of decomposition from -185 to -160 and -110 kJ/mol, respectively. Under most conditions investigated, the temperature at which gas flow was initiated was 147-150 degrees C. The presence of iron reduced this temperature to 140 degrees C. Decomposition was observed to take place over two stages, where the sample was heated directly from 40 degrees C at the required heat up rate. Where the sample was heated in stages and where calibrations had been carried out preceding decomposition, the decomposition took place in one stage alone.
Lever
Sarah D
SD
School of Process Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, UK.
Papadaki
Maria
M
D001565:Benzoates / Q000737:chemistry*; D002151:Calorimetry / Q000379:methods; D005740:Gases / Q000737:chemistry; D006361:Heating; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry*; D013696:Temperature
D001565:Benzoates; D005740:Gases; D009566:Nitrates; C013409:benzoyl chloride