Objective Liquid-liquid catalytic oxidation sweetening process is widely used by refinery enterprises to remove the mercaptan in liquefied petroleum gas (LPG) and other light hydrocarbon products. However, organic waste gas produced in the process with odor, is one of the challenge in VOCs treatment. The objective of this study is to develop an sweetening organic waste gas emission reduction technology to solve the problem from the source.

Methods Based on the understanding of the reaction of LPG sweetening process, this study analyzed the formation characteristics of waste gas and the factors affecting oxygen consumption, which enabled the development and industrial application of the gas internal circulation technology to replace the factory air with oxygen and add the raw material pretreatment for process integration.

Results In a refinery and chemical enterprise equipped with the developed technology, the average volume fraction of oxygen and hydrocarbon components in circulating gas was 9.7% and 21.7%, respectively, while the volume fraction of injected oxygen was not less than 90.0% and the emission of organic waste gas was reduced from 97.6 m³/h to 0.0 m³/h, achieving good application effect realize the zero emission of sweetening organic exhaust gas.

Conclusions The emission reduction technology can reduce the organic waste gas emission to 0.0 m³/h, carry out the VOCs treatment at the source, and meet the increasingly stringent environmental protection requirements and the clean production and emission reduction requirements of the refining and chemical enterprises.