Patent ID: 6927310

Claim:
In a method for recovering multiple separate tripropylene glycol products from a mixture of dipropylene glycol, tripropylene glycol, tetrapropylene glycol, glycols heavier than tetrapropylene glycol, and at least one aldehyde compound, wherein a blend of dipropylene glycol and tripropylene glycol is removed from said mixture thereby leaving a composition that contains a major amount of tripropylene glycol and minor amounts of dipropylene glycol, at least one aldehyde, tetrapropylene glycol, and glycols heavier than tetrapropylene glycol, the improvement comprising separating from said composition a first stream consisting essentially of tripropylene glycol and aldehyde thereby leaving the remainder of said composition as a second stream concentrate that contains residual tripropylene glycol and aldehyde, deliberately keeping said first stream physically separate from said second stream concentrate, mixing with said first stream at least one additive that reacts with and neutralizes said aldehyde, said additive being employed in an amount sufficient to produce a first individual tripropylene glycol product that contains no more than 20 ppm of said aldehyde and which contains said neutralizing additive, and separately removing said second stream concentrate to a separate processing step to form a second separate individual tripropylene glycol product that contains essentially no neutralizing additive.