Environmental-protection process method for removing ammonia from ammoxidation synthesis gas

Abstract

The invention provides an environmental-protection process method for removing ammonia from ammoxidation synthesis gas. The method is characterized in that a combined ammonia removal technological method composed of a primary ammonia removal process using phosphoric acid or ammonium dihydrogen phosphate and a fine ammonia removal process using sulfuric acid or ammonium bisulfate. In the primary ammonia removal process of ammoxidation synthesis gas, primary ammonia removal and ammonia recovery of the synthesis gas can be achieved through the repeated cycle of the following steps: phosphoric acid or ammonium dihydrogen phosphate absorbs free ammonia in the synthesis gas as a carrier in a primary ammonia removal tower, and is transformed to diammonium hydrogen phosphate; and diammonium hydrogen phosphate produces free ammonia in a desorption tower, and is transformed to ammonium dihydrogen phosphate. The ammoxidation synthesis gas enters a fine ammonia removal tower after the primary ammonia removal process, and fine ammonia removal process is achieved by using sulfuric acid or ammonium bisulfate as an absorber to absorb remaining ammonia in the synthesis gas after the primary ammonia removal process in a fine ammonia removal tower, wherein sulfuric acid or ammonium bisulfate is transformed to ammonium sulfate byproducts. The combined ammonia removal method can recover free ammonia in the ammoxidation synthesis gas to save resources and achieve real environmental protection property of the ammonia removal process, and has good economic and social benefits.

Description

Technical field [0001] An environmentally friendly process for removing ammonia from synthesis gas by ammonia oxidation refers to a process for removing and purifying free ammonia in the reaction gas after ammonia oxidation using ammonia as an ammonia source, fully considering the recovery and utilization of ammonia The environmental protection of the technological process belongs to the environmentally friendly clean technological method. Background technique [0002] Ammoxidation reaction is a well-known process. It uses ammonia and oxygen to convert organic substances that can be ammoxidized into cyanide at high temperature in the presence of an ammoxidation catalyst. The technical value applications of the ammoxidation reaction include, for example, the production of acrylonitrile from propylene, the production of benzonitrile from toluene, the production of phthalonitrile or terephthalonitrile from ortho or para-xylene, and the production of 3-picoline 3-cyanopyridine and t...

AI Technical Summary

Problems solved by technology

This method of using phosphoric acid or ammonium dihydrogen phosphate as a carrier to realize the removal and recycling of free ammonia in syngas can obtain beneficial effects to a certain extent, but due to the stability of diammonium hydrogen phosphate is limited; therefore, using Phosphoric acid or ammonium dihydrogen phosphate absorbs the free ammonia in the synthesis gas, and the thoroughness of the removal of the free ammonia in the synthesis gas is still not well solved, and there is still a certain amount of free ammonia in the treated synthesis gas; especially when the temperature of the treated synthesis gas system is at If it is higher, the content of residual free ammonia in the syngas will be higher, and it is difficult to meet the treatment requirements; if the treatment temperature is controlled at a lower level, a certain amount of other substances will be dissolved in the treatment liquid system, which will hinder the pre-analysis and treatment. The analysis process brings other unfavorable factors; therefore, it is greatly limited in actual production and cannot be well promoted

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