| 2,4-dinitrochlorobenzene is an important kind of fine chemicals intermediate, and is used extensively in many fields. So, it has a great developmental future of market. Additionally, there are some disadvantages in the traditional processes, such as environment pollution and energy waste. Therefore, the process of chlorobenzene nitrated to 2,4-dinitrochlorobenzene with continuous and adiabatic nitration was studied. The results are as follows:A set of continuous and adiabatic nitration equipment which included four reactors in series were designed. The equipment was debugged and revised with aqueous simulation experiment, then was debugged and revised with reactants. It fitted in with experimental needs for the process of 2,4-dinitrochlorobenzene.The main influencing factors were investigated with orthogonal test, these factors included: molar ratio of nitric acid to chlorobenzene (φ), mass fraction of sulfuric acid (S) and quality fraction of nitric acid (N) in mixed acid, volume flux of reactants (Q). Their influencing order on the reaction was that: N＞Q＞φ＞S.Effects of the above-mentioned each factors on reaction were investigated seriatim with single factor method. The optimal synthesis conditions were obtained, that was:φ=2.22, S=0. 680, N=0.220, W=0. 100(W: mass fraction of water in mixed acid), Q=16mL.min-1(Qc=3.46 mL.min-1(Qc: volume flux of chlorobenzene)), t=40min(t: reaction residence time). In the optimal condition, conversion rate of chlorobenzene was 100%, selectivity of reaction was 95.4%, yield of products was 95.4%, based on chlorobenzene, content of 2,4-dinitrochlorobenzene in the raw products was 96.39%. Melting point and crystallization point of the raw products were measured, melting point 49.8℃, crystallization point 47.48℃. The stability and repetition of the synthesis experiment were measured and were satisfying, average yield of products in these experiments was over 95%.The crystallization process was studied for raw products to be crystallized with melting crystallization method, the crystallization process was studied, the optimal conditions of crystallization were obtained, that was: in the range of crystallization temperature 47～45℃, descending velocity of crystallization temperature was 3℃.(15.min)-1, in the range of crystallization temperature 45～22℃, descending velocity of crystallization temperature was 4.5℃.(15.min)-1, crystallization timeτc was 140min; in the range of exudation temperature 22～43℃, ascending velocity of exudation temperature was 6℃.(15.min)-1, in the range of exudation temperature 43～46℃, ascending velocity of exudation temperature was 3℃.(15.min)-1, exudation timeτE was 248min, the whole time of the crystallization experiment was 388min. In the condition, content of 2,4-dinitrochlorobenzene in the end product was 99.10%, based on the quality of the raw product, yield was 91.91%. The stability and repetition of the crystallization experiment were measured and were satisfying, error of these crystallization experiments was not more than 0.03%. Melting point and crystallization point of the end products were measured, melt point was 50. 9℃, crystallization point was 48.61℃. The end products met the national chemical industry criterion of high-grade product HG/T 2553-2003.The disposal and recycle of waste acid were studied. First of all, nitric acid and organic compounds in the waste acid were disposed by the method that chlorobenzene was added into the waste acid and reacted with nitric acid at first, then the outgrowth was extracted. After that, the excess water was removed with distillation and concentration.Both mass fraction of nitric acid and mass fraction of organic compounds in the waste acid disposed were not more than 0.01, mass fraction of sulfuric acid in the waste acid disposed was about 0.92, mass fraction of water in the waste acid disposed was 0.06～0.07. It met the requirement of reuse.In the process which used mixed acid prepared by waste acid disposed, conversion of chlorobenzene was 100%, selectivity was 93.8%. Based on chlorobenzene, yield was 93.8%. In comparition with the process which used the mixed acid prepared with fresh materials, conversion rate of chlorobenzene was the same, difference of their selectivity was not more than 2%, difference of their yield was not more than 2%, the result was satisfying.
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