We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Process optimization, thermal hazard evaluation and reaction mechanism of m-xylene nitration using HNO3-Ac2O as nitrating reagent.
- Authors
Yao, Hang; Fu, Gang; Ni, Yuqing; Ni, Lei; Jiang, Juncheng; Zhang, Han; Cheng, Zhen; Chen, Zhiquan
- Abstract
Nitro-m-xylenes (NMX) was synthesized in semi-batch mode via m-xylene nitration using nitric acid-acetic anhydride (HNO 3 -Ac 2 O) as nitrating reagent in this work. The nitration process was optimized by response surface methodology. The yield of NMX could reach 92.40% under the optimal conditions of jacket temperature of 20 °C, 0.15 mol of HNO 3 and 0.19 mol of Ac 2 O. Corresponding large reaction enthalpy (Δ H =240.9 kJ/mol) and adiabatic temperature rise (Δ T ad,r =398.1 K) indicated the serious hazards of nitration in a thermal runaway scenario. Pyrolysis of nitration products occurred at about 320–400 °C by differential scanning calorimetry tests. The reaction order of the pyrolysis was determined to be 1.2 by adiabatic kinetic analysis. Thermal risk of the nitration process was assessed to be acceptable and level 1 via the risk matrix and Stoessel criticality diagram analyses, respectively. Furthermore, detailed nitration mechanisms for NO 2 + generation and aromatic substitution were presented. The activation free enthalpy and free energy parameters for each step were calculated by density functional theory (DFT). These findings can help understand the exothermic sources of m-xylene nitration and guide the intrinsically safer design and scale-up of the process.
- Subjects
NITRATION; PROCESS optimization; GIBBS' free energy; RESPONSE surfaces (Statistics); HEAT of reaction
- Publication
Process Safety & Environmental Protection: Transactions of the Institution of Chemical Engineers Part B, 2024, Vol 182, p1008
- ISSN
0957-5820
- Publication type
Article
- DOI
10.1016/j.psep.2023.12.062