Fractional Extraction Process for Recovery of Pure Tar Acids

Abstract

Caustic soda extraction of tar acids from tar distillates has the disadvantages of batch operation and consumption of reagents. A review of the literature showed that continuous solvent extraction methods had been explored using oxygenated solvents. These processes were not too satisfactory, owing to the production of impure tar acids or the necessity of recycling a substantial fraction of the tar acids to obtain a satisfactory recovery.

Pure Cresylic Acids from Petroleum by Solvent Extraction

“…The recovery and recycle of methanol and hexane were demonstrated successfully. A commercial plant (7) at our Newark chemical plant, Pitt-Consol Chemical Co., involving a 3 X 60 foot Scheibel-type extraction column has been in operation for five years with a capacity of 20,000,000 to 25,000,000 pounds of refined cresylic acids. Composite crude cresylic acids from at least 20 different petroleum refineries are processed.…”

“…The liquid pyrolysis products of hexadecane (7, 77) and paraffin wax (5, 13, 14) consist largely of the homologous linear a-olefins together with small amounts of the homologous paraffins. The gaseous products consist principally of methane, ethane, ethylene, and propene (5,7,77). The observed composition of the products in general conforms with the composition predicted from the radical chain decomposition theory of Rice and Kossiakoff (7,8,17).…”

“…The gaseous products consist principally of methane, ethane, ethylene, and propene (5,7,77). The observed composition of the products in general conforms with the composition predicted from the radical chain decomposition theory of Rice and Kossiakoff (7,8,17).…”

“…Extraction studies were carried out in a 1 inch X 8 foot extraction column of the Scheibel type (7), which contained 28 stages. The shell was constructed of borosilicate glass pipe, while the column internals were of Type 304 stainless steel.…”

“…A novel fractional extraction process was developed (5) which almost completely eliminates both thiophenols and disulfides with a recovery of cresylic acids exceeding 95%. The solvents, aqueous methanol and hexane, were those used in earlier studies in our laboratory to separate cresylic acidhydrocarbon mixtures (3,7). The cresylic acids dissolve in the aqueous methanol solvent, while the sulfur compounds are removed by the hydrocarbon solvent.…”