Method for preparing oxalate tail gas by purified CO coupling

A coupling technology for producing oxalate and tail gas, which is applied to chemical instruments and methods, separation methods, and separation of dispersed particles. Eliminate the difficult control of the removal process and achieve the effects of light weight, increased effective specific surface area, and small volume

Inactive Publication Date: 2014-05-07
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Patent CN92110531.2 discloses a method for eliminating nitrogen oxide gas from polluting the environment. The method first mixes exhaust gas containing nitrogen oxide gas with oxygen and alcohols for oxidative esterification to form nitrite, and then nitrates at 0.05 to 10.0 Under MPa pressure and -20°C~100°C temperature conditions, the nitrite is condensed into a liquid and separated from the non-condensable gas to recover the nitrite, but this technology consumes a lot of energy and the process of removing nitrogen oxides in the exhaust gas Difficult to control
Patent CN201010147040.0 discloses a method for CO coupling oxalate tail gas treatment, the method firstly mixes the tail gas stream containing nitrogen oxides with oxygen or air and C 1 ~C 4 The alkanol enters the first rotating packed bed for the first reaction, and the obtained gas phase reactant flow is contacted with the oxidant to react, and then the reacted gas phase flow and urea solution are sent to the second rotating packed bed for reaction, and finally the The treated gas is vented, but the reaction between the gas phase stream and the oxidant in the second step of the method is difficult to control, and the operating conditions for urea solution absorption are not described in detail in the patent

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] The tail gas stream with a nitrogen oxide content of 1% and oxygen are respectively fed from the bottom of the methanol absorption tower, and methanol is fed from the top of the methanol absorption tower. At a temperature of 5°C and a pressure of 0.6MPa, methanol and nitrogen are oxidized The reaction is carried out at a molar ratio of 30:1 and a molar ratio of nitrogen oxides to oxygen of 4:1. The obtained liquid stream is recycled, and the obtained gas stream and acidic urea solution are respectively sent to the supergravity rotating packing In the bed, the acidic urea aqueous solution is a uniform mixed solution of urea, water and nitric acid. The urea concentration is 30%, the pH is 3, the temperature is 35℃, the pressure is 0.1MPa, and the liquid-to-air ratio is 20L / m 3 , The absorption reaction is carried out under the condition of the rotor speed of 3000 rpm, and the emission content of nitrogen oxides in the exhaust gas after absorption is 80 ppm.

[0015]

Embodiment 2

[0017] The raw material composition of the tail gas stream, the operating conditions of the methanol absorption tower and the supergravity rotating packed bed are all the same as in [Example 1], except that the type of acid is changed. The specific results are shown in the following table:

[0018] Type of acid sulfuric acid hydrochloric acid acetic acid Emission content of nitrogen oxides in exhaust gas after absorption, ppm 120138175

Embodiment 3

[0020] The raw material composition of the tail gas stream and the operating conditions of the methanol absorption tower are the same as in [Example 1]. The super-gravity rotating packed bed is replaced with an absorption tower. The operating conditions of the absorption tower are that the acidic urea aqueous solution is composed of urea, water and nitric acid. Uniformly mixed solution, with a urea concentration of 25%, a pH of 3, a temperature of 65°C, a pressure of 0.2MPa, and a liquid-gas ratio of 80L / m 3 The absorption reaction is carried out under the conditions of, and the emission content of nitrogen oxides in the exhaust gas after absorption is 120 ppm.

[0021]

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Abstract

The invention relates to a method for preparing oxalate tail gas by purified CO coupling. The method mainly solves the technical problem that a removal rate of nitric oxide is low in the prior art. The method comprises the following steps that (a) a tail gas flow, oxygen or air containing nitric oxide and methanol are led in a methanol absorption tower for reaction from a gas inlet and a liquid inlet; a gas phase flow and a liquid phase flow are obtained; and (b) the gas phase flow obtained in Step (a) and an acid urea solution are led in absorption towers or supergravity rotary packed beds; the absorption towers or the supergravity rotary packed beds are connected in series; and the reaction is performed under the conditions that the urea concentration is 5-40%, a pH (power of hydrogen) value is 1-5, the temperature is 20-80 DEG C, the pressure is 0.1-0.5MPa and a liquid-gas ratio is 5-100L/m<3>. With the adoption of the technical scheme, the problem is solved better, so that the method can be used in industrial production of nitric oxide in oxalate tail gas preparation by removed CO coupling.

Description

Technical field [0001] The invention relates to a method for purifying the tail gas of CO coupling to produce oxalate, in particular to a method for removing nitrogen oxides from the tail gas of CO coupling to produce dimethyl oxalate. Background technique [0002] Oxalate is an important chemical raw material and can be used to prepare oxalic acid, ethylene glycol, carbonate, oxalamide, intermediates for drugs and dyes, plastic accelerators and solvents. In addition, low-pressure hydrogenation of oxalate can produce ethylene glycol, an important chemical raw material. In recent years, although the production capacity and output of ethylene glycol in my country have increased rapidly, due to the strong demand of polyester and other industries, it is still unable to meet the increasing demand of the domestic market and has to be imported in large quantities every year. In 2010 (1-10 ) The monthly import volume was 5.5867 million tons. [0003] At present, there are two main types o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/75B01D53/78B01D53/56
Inventor 孙凤侠赵焱蒯骏
Owner CHINA PETROLEUM & CHEM CORP
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