| 摘要 |
Isobutylene containing n-olefins is purified by contact with a 5Ä crystalline aluminosilicate molecular sieve at less than 150 DEG F. maintaining a superficial velocity of 0,2-1,5 ft./sec. through the adsorption zone. The space velocity may be 0,5-2 wt./wt./hr. and the temperature below 130 DEG F., e.g. 80-100 DEG F. The sieve is desorbed alternately with adsorption periods, desorption being effected by heating to 400 DEG -750 DEG F., e.g. using hot natural gas, to strip n-butenes and polymers from the sieve. The sieve is then cooled to 120 DEG F. by circulating methane or isobutane at 50-150 p.s.i.g., the gas being cooled during the circulation with water and liquid isobutylene. The sieve is further cooled to 75 DEG -90 DEG F. by reducing the pressure to 30-50 mm. Hg. followed by repressuring with isobutylene. Preferably adsorption pressure is 0-5 p.s.i.g. during the first 3-6 cycles and then increased to 10-25 p.s.i.g. and feed rate is preferably reduced during each adsorption period. The sieve may be split into 2-4 isolated beds used one at a time sequentially during adsorption periods but all desorbed together. Reference has been directed by the Comptroller to Specification 850,415. |
