| 摘要 |
<p>The continuous two-stage prodn. of dinitrotoluene (DNT) isomer mixts. by nitration of toluene comprises: (1a) reaction of toluene in a continuous reactor with a nitrating acid contg. (i) 80-100 wt.% inorganic components comprising 60-90 wt.% H2SO4, 1-20 wt.% HNO3 and at least 5 wt.% water, and (ii) 0-20 wt.% organic components comprising 70-100% nitrotoluene isomers plus by-prods., under adiabatic conditions at 0-140 (pref. 20-140) degrees C with a mole ratio of (HNO3):(toluene) = (0.7:1)-(1.2:1), (1b) separating the two phases, (1c) removing at least 5% of the water from the acid phase by flash evapn., opt. with heating, opt. adding 50-100 wt.% HNO3 and returning continuously to stage (a), (2a) reacting the organic phase (mainly mononitrotoluene (MNT)) under adiabatic conditions at 20-200 (pref. 40-180, esp. pref. 60-170) degrees C with a nitrating acid as above in the same range of mole ratios, (2b) separating into two phases, (2c) concentrating the acid phase by flash evapn. as in (1c), with addn. of MNT from stage (1) to the vapour from the concn.</p> |
