Methods for inhibiting vinyl aromatic monomer polymerization
AssigneeBetz Laboratories, Inc.
InventorGraciela B. Arhancet
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Abstract
An improved method for inhibiting the polymerization of vinyl aromatic monomer with a hydroxylamine compound is disclosed. The improvement provides for adding a catalytic amount of a phenylenediamine compound to the vinyl aromatic system while replacing any phenylenediamine compound lost as a result of physical removal from the system via the waste stream.
Claims8
A method for inhibiting the polymerization of vinyl aromatic monomers in an oxygen-free vinyl aromatic processing system containing a continuous feed stream of vinyl aromatic monomer, a continuous recycle stream returning to said feed stream, at least one process column, and waste stream, comprising adding to said feed stream a sufficient polymerization inhibiting amount of a hydroxylamine compound, the improvement comprising the steps of:
- a) using a phenylenediamine compound as a catalyst in said feed stream wherein said phenylenediamine compound will catalytically improve the polymerization inhibiting effect of said hydroxylamine compound;
- and
- b) maintaining the amount of said phenylenediamine compound in said process column in a weight ratio of 1:9 to 9:1 with said hydroxylamine compound.
Dependencies are inferred from the claim text.