The three compounds benzene, toluene and xylene, also known as BTX for short, are among the three basic materials of the petrochemical industry, for a total of about 120 million tons of these materials are produced and consumed annually in the petrochemical industry.
Primary sources for the production of aromatics are catalytic reforming processes as well as pyrolysis gasoline produced in steam cracking units. Catalytic conversion processes are commonly used in crude oil refineries to produce high-octane gasoline. The steam cracking method is also used to produce light olefins such as ethylene. If liquid feed is used in these units, a by-product rich in aromatics is produced called pyrolysis gasoline. Compounds of benzene, toluene and xylene can be extracted from it. Normally, at first, aromatic compounds are separated from non-aromatic ones by extractive distillation method, and then, in the next step, benzene, toluene and xylene compounds are separated by distillation mechanism.
Comparison of the consumption volume of each of the BTX compounds as well as their production volume in the primary processes indicates that the production volume of toluene compounds is in excess of the demand. Therefore, secondary processes have been developed to convert toluene to benzene (Hydro Dealkylation process). ) As well as xylene (Disproportionation).
Due to the growing demand for aromatics in the world, companies have developed new processes for the direct production of BTX, including AROMAX, which has the ability to convert light naphtha to aromatics. The CYCLAR process is also used to convert liquefied petroleum gas to BTX. A process called ALPHA also converts four-carbon olefins to BTX.
The Middle East region produced 2.8, 1.6 and 3.4 million tons of benzene, toluene and xylene in 2014, respectively. The North American region and the European Union also produced and consumed 6.8 and 6.5 million tons of benzene, respectively.