Economic analysis of diesel production from coal tar

Coal tar is a liquid product obtained from coal during processes of carbonization and gasification. Depending on the carbonization temperature and method, several types of tar can be produced: low-temperature (450°C–650°C) coal tar, low- and medium-temperature (600°C–800°C) producer’s tar, medium-temperature (900°C–1000°C) vertical furnace tar, and high-temperature (1000°C) coking tar. The main components of low-temperature coal tar are naphthenes and alkanes, with a low content of aromatic hydrocarbons. Its hydrocarbon composition is related to the quality of the raw coal; its overall composition is similar to that of crude oil. Therefore, low-temperature coal tar is one of the important sources of synthetic petroleum. At present, the project for producing qualified light diesel from low-temperature coal tar is still in the stage of failure in both laboratory and pilot-scale tests in China, whether using standalone reactors or tubular furnaces. Many manufacturers in this industry are constantly working to improve their equipment and process technologies, and have developed innovative approaches in these areas; yet the diesel produced still fails to meet the acceptance standards for light diesel. The analysis shows that the main reason is the excessive focus on improving equipment and processes, at the expense of attention to the use of catalysts and an understanding of catalytic cracking. Practice has proven that merely upgrading equipment and processes is not sufficient to ensure that low-temperature coal tar meets the acceptance standards for light diesel; it is the use of catalysts that proves to be key. In the fine chemical industry, 70-80% of product synthesis relies on the catalytic action of catalysts; these catalysts can shorten reaction times and improve both the quantity and quality of products. Catalysts are thus the best way to \"upgrade\" equipment.