Petrochemical Processing Udex process

Section, which appears every month. It also has a special section on Patents which lists new patents according to their classification. The Process Issue of the Petroleum Refiner is now carrying a special section on Petrochemical Processes. In the September 1952 issue for example, Extractive Distillation for Aromatic Recovery, Modified SO2 Extraction for Aromatic Recovery, Udex Extraction, Ethylene Manufacture by Cracking, Ethylene Production, Hypersorption, Hydrocol, Dehydrogenation (for butadiene), and Butadiene Process, were described. These descriptions include the main essentials of the process, simplified flow diagrams, and the name of the company offering it. Formerly these processes were described under the Process Section. 

Gycloaliphatics and Aromatics. Cychc compounds (cyclohexane and benzene) are also important sources of petrochemical products (Fig. 14). Aromatics are ia high concentration ia the product streams from a catalytic reformer. When aromatics are needed for petrochemical manufacture, they are extracted from the reformer s product usiag solvents such as glycols (eg, the Udex process) and sulfolane. 

Removal of Aromatic Compounds. Because of the demand for high-purity aromatic compounds for petrochemical feedstocks, several processes have been developed for BTX (benzene, toluene, and xylenes) recovery from distillate streams. In these processes, aromatic compounds are separated from nonaromatic compounds by liquid—liquid extraction using polar solvents. The three major processes in use are the UOP—Dow UDEX process (di- or triethylene glycol solvent), the UOP sulfolane process (tetrahydrothiophene 1,1-dioxide), and the Union Carbide TETRA process (tetraethylene glycol). 

Liquid-liquid extraction provides one of the most important commercial processes for performing group separations between aromatic and aliphatic species in the petrochemical industry. One of the earliest proven processes, the Udex system, is summarized in Fig. 7.8-9. It is based on the use of diethylene gly and water, a polar solvent, which selectively extracts the more polar aromatic conqxxmds fiom the nonpolar aliphatic species. A variety of solvents have been used including diethylene and Iriethylene glycols," N-methyl pyrrolidine, sulfolane, and other polar solvents. The basic process configurations ate similar to those already described, but in some cases a 1 solvent system may be used to remove asphaltic materials simultaneously. More recent studies give further consideration to alternative solvents for this application. 

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