Removal of carbonyl sulphide and organic combined sulphur from gases containing olefines

摘要

PICT:0981656/C4-C5/1 Carbonyl sulphide and organic combined sulphur are removed from olefin containing gases by washing under superatmospheric pressure with a caustic alkali solution of 2 to 6% by weight of the total weight of the solution at 50 DEG to 110 DEG C. in one or more reaction vessels whose exchange surface is not less than 2 sq. m./cu. m. of the hourly throughput of gas. Starting materials used may be obtained by thermal or autothermal cracking of petroleum or fractions thereof. Preferably the process takes place at 85 DEG to 95 DEG C. at a pressure of 10 to 35 atmospheres. As shown, an olefin containing gas having the composition 8.7% CO, 14.3% H2, 5.1% N2, 25.3% CH4, 8.0% C2H6, 0.4% C3H8, 29.8% C2H4, 6.8% C3H6 and 1.6% C4H8 is introduced through pipe 1 and contacts in absorption tower 2 caustic soda solution supplied in countercurrent flow through pipe 6. Tower 2 is filled with 35 mm. steel rings to a depth of 15 m., the internal diameter of the tower being 1.3 m., so that an exchange surface of about 4 sq. m./cu. m. of gas results. Purified olefin containing gas passes out through line 3 and the caustic soda solution is recycled through retention tank 8, pump 9 and heater 5. Spent liquor may be withdrawn from the system through pipe 10 and used for a preliminary purification step and an equivalent volume of fresh caustic soda solution supplied through pipe 4. The carbonyl sulphide and organic combined sulphur can thus be removed to the extent of 90% or more. Columns having suitable baffles or a packing of conventional tower packing, e.g. packed columns, bubble tray columns and bubble columns are also suitable as reactors in the process of the present invention, which may be continuous or batchwise.