Thermal runaway characteristics and mechanism of nitric acid-styrene hybrid system

doi:10.16265/j.cnki.issn1003-3033.2019.11.006

Abstract

Abstract: Nitric acid oxidation is the key technology for the decolorization and refining of crude styrene. In order to investigate the thermal stability, adiabatic runaway characteristics, thermal runaway dynamics and runaway initiation mechanism of the reaction system, C600 thermal scanner, VSP2 adiabatic calorimeter, ReactIR in-situ FTIR spectrometer, combined with ReaxFF molecular dynamics simulation method were used to carry out experiments. The results show that θ₀ of styrene self-polymerization runaway is 132 ℃, the Δθ_ad is 209 ℃, the P_max is 1.2 MPa, the Ea is 131.3 kJ/mol, and the reaciton order is 3.6. The runaway process containing nitric acid is divided into two stages. The first stage is the styrene side chain oxidation reaction, and the θ₀ is 51 ℃, the Δθ_ad is 70 ℃, the Ea is 71.3 kJ/mol, and the reaciton order is 0.3. The second stage is styrene self-polymerization runaway, and the θ₀ is 131 ℃, Δθ_ad is 152 ℃, and P_maxis 2.1 MPa. In the industrial production process, it is necessary to strictly control the proportion of nitric acid in decolorization reaction, lower the reaction temperature, and prevent side reactions such as nitrification and oxidation.

Key words: nitric acid, styrene, reaction runaway, adiabatic temperature rise(Δθ_ad), fourier transform infrared(FTIR), molecular dynamics simulation

CLC Number:

X937

ZHU Yunfeng, QIAN Ya'nan, XU Wei, JIANG Juncheng, SHI Ning, WANG Zhirong. Thermal runaway characteristics and mechanism of nitric acid-styrene hybrid system[J]. China Safety Science Journal, 2019, 29(11): 32-38.

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