Process for olefin oxide detoxification

In a continuous process for removing olefin oxide having 2 or 3 carbon atoms from exhaust gases containing an inert diluent discharged from ethylene oxide sterilizers, the improvement comprising

• contacting said exhaust gases with an aqueous absorbing liquid having a pH between about 0.5 and 7.5 and a temperature less than about 70 degrees F. causing absorption of at least about 97% of the olefin oxide into said aqueous liquid, said contacting being conducted at an absorbing liquid-to-gas flow rate ratio of about 40 to 500 gal/100 ft.sup.3 ;
• feeding said aqueous liquid containing absorbed olefin oxide at a temperature of less than about 120 degrees F. into a reactor containing an acid catalyst at concentration of about 0.01 to 1 gram-mole per liter, said reactor being at atmospheric pressure or slightly above atmospheric pressure;
• reacting said aqueous liquid for a time sufficient to convert at least 97% of the olefin oxide to products including an alkylene glycol while continuously removing sufficient quantities of aqueous liquid from the reactor to keep the volume of solution in the reactor constant;
• compressing the olefin oxide-free exhaust gases after contact with the aqueous absorbing liquid to a pressure of about 130 to 170 psig;
• cooling the gas/liquid from the compressor to a gas/liquid temperature of about -20 to 50 degrees F.;
• separating an inert diluent-free gas stream from the inert diluent;
• and
• recovering the inert diluent having a purity above about 99% by weight.

In a process for removing olefin oxide having 2 or 3 carbon atoms from exhaust gases containing an inert diluent discharged from ethylene oxide sterilizers, the improvement comprising:

• contacting said exhaust gases with an adsorbent bed capable of adsorbing an olefin oxide to provide an olefin oxide-free gas stream;
• regenerating the olefin oxide from the adsorbent bed periodically to provide a more concentrated olefin oxide gas composition;
• contacting said concentrated olefin oxide gas composition with an aqueous absorbing liquid at ambient pressure having an initial pH between about 0.2 and 8 and an initial temperature less than about 80 degrees F. causing absorption of at least about 97% of the olefin oxide into the aqueous liquid, said contacting being conducted at an absorbing liquid-to-gas flow rate ratio of about 40 to 500 gal/1000 ft.sup.3 ;
• feeding the aqueous liquid containing the absorbed olefin oxide at a temperature of less than about 120 degrees F. and an acid catalyst at a concentration of about 0.01 to 1 gram-mole per liter into a reactor, said reactor being at atmospheric pressure or slightly above atmospheric pressure;
• reacting said aqueous liquid for a time sufficient to convert at least 97% of the olefin oxides to products including an alkylene glycol while continuously removing sufficient quantities of aqueous liquid from the reactor to keep the volume of solution in the reactor constant;
• recycling the aqueous liquid leaving the reactor, after cooling, back to the absorber for further absorption of olefin oxide;
• compressing the olefin oxide-free exhaust gases to a pressure of about 130 to 170 psig;
• cooling the gas/liquid from the compressor to a gas/liquid temperature of about -20 to 50 degrees F.;
• and
• recovering the inert diluent having a purity above about 99% by weight.