Method and device for removing contaminants arising during the production of aliphatic nitrate esters

Abstract

The invention relates to a method and to a device for removing contaminants arising during the production of aliphatic or alicyclic nitric acid esters, in particular for removing contaminants from nitrated crude nitric acid esters, which nitrated crude nitric acid esters arise during the nitration of monovalent or multivalent aliphatic or alicyclic alcohols capable of nitration, after the separation of the final nitrating acid, and to a production system for nitrating monovalent or multivalent aliphatic alcohols capable of nitration with subsequent purification of the nitrated nitric acid esters.

1 . An apparatus for removing impurities obtained in the preparation of aliphatic or cycloaliphatic nitric esters by removing impurities from crude nitric esters obtained in the nitration of nitratable monohydric or polyhydric aliphatic or cycloaliphatic alcohols, after removal of the residual nitrating acid, via treatment with at least one washing medium, wherein the apparatus comprises the following devices:
 (a) at least one dispersing device for contacting and emulsifying crude nitric esters to be purified and a washing medium; and,   (b) arranged downstream of the dispersing device, a tube reactor for introducing the emulsion comprising the crude nitric esters to be purified and the washing medium and produced in the dispersing device, wherein the tube reactor is equipped with mixing elements for introducing additional mixing energy, so that the impurities initially present in the crude nitric esters are at least partially removed during passage of the emulsion through the tube reactor and are at least partly transferred into the washing medium and neutralized thereby during passage of the emulsion through the tube reactor; and   (c) arranged downstream of the tube reactor, a separation device for separating the nitrated products which have been freed of the impurities from the washing medium.   
     
     
         2 . The apparatus as claimed in  claim 1 ,
 wherein the mixing elements are static mixing elements configured as metal plates, as impingement plates, as deflection plates, as orifice plates, as static mixers or as flow dividers;   wherein the mixing elements are fixed to the inside of the tube reactor;   wherein the pressure drop per mixing element is from 0.2 bar to 3.0 bar;   wherein the dispersing device is configured as jet mixer or pump; and   wherein the dispersing device is integrated into the tube reactor or is a constituent of the tube reactor.   
     
     
         3 . A production plant for the preparation of nitric esters of monohydric or polyhydric aliphatic or cycloaliphatic alcohols via nitration of monohydric or polyhydric aliphatic or cycloaliphatic alcohols with subsequent purification of the crude nitrated products formed in the nitration, wherein the production plant comprises the following units:
 (a) a nitration unit for the preparation of nitric esters of monohydric or polyhydric aliphatic or cycloaliphatic alcohols via nitration of monohydric or polyhydric aliphatic or cycloaliphatic alcohols, wherein the nitration unit comprises one or more reaction vessels for carrying out a nitration reaction;   (b) in the production line arranged downstream of the nitration unit, a separation device for the removal of the residual nitrating acid from the nitrated crude products in the form of crude nitric esters;   (c) in the production line arranged downstream of the separation device, a washing facility for carrying out the washing of the crude nitrated products,   wherein the washing facility comprises:
 at least one dispersing device for contacting and emulsifying the crude nitric esters to be purified and a washing medium, resulting in an emulsion comprising the crude nitric esters and the washing medium; and, 
 arranged downstream of the dispersing device, a tube reactor for introducing the emulsion comprising the crude nitric esters to be purified and the washing medium and produced in the dispersing device, wherein the tube reactor is equipped with mixing elements for introducing additional mixing energy, so that the impurities initially present in the crude nitric esters are at least partially removed during passage of the emulsion through the tube reactor and the impurities initially present in the crude nitric esters are at least partly transferred into the washing medium and neutralized thereby during passage of the emulsion through the tube reactor; 
   (d) optionally, in the production line arranged downstream of the washing facility, a stirred vessel for increasing the contact and residence time between nitric esters and washing medium; and   (e) in the production line arranged downstream of the washing unit and the optional stirred vessel, a separation device for separating the nitric esters which have been freed of the impurities from the washing medium.   
     
     
         4 . The production plant as claimed in  claim 3 , wherein the mixing elements are static mixing elements configured as metal plates, as impingement plates, as deflection plates, as orifice plates, as static mixers or as flow dividers. 
     
     
         5 . The production plant as claimed in  claim 3 , wherein the mixing elements are fixed to the inside of the tube reactor. 
     
     
         6 . The production plant as claimed in  claim 3 , wherein the mixing elements are configured as push-in elements, with the push-in elements being inserted as required according to number and position in the tube reactor. 
     
     
         7 . The production plant as claimed in  claim 3 , wherein a volume-based mixing energy of from 20 to 1000 joule/liter is introducable by the mixing elements in the tube reactor. 
     
     
         8 . The production plant as claimed in  claim 3 , wherein the pressure drop per mixing element is from 0.2 bar to 3.0 bar. 
     
     
         9 . The production plant as claimed in  claim 3 , wherein the dispersing device is configured as jet mixer or pump. 
     
     
         10 . The production plant as claimed in  claim 3 , wherein the dispersing device is configured such that it produces a central driving jet and an annular jet surrounding the driving jet. 
     
     
         11 . The production plant as claimed in  claim 3 , wherein the dispersing device is located upstream of the reactor, with the dispersing device going over into the tube reactor.