Abstract: There is described a process for depolymerizing polyesters such as polyethylene terephthalate polyester to monomer components comprising esters such as dimethyl terephthalate and purifying the ester by sublimation, which purified ester can then be used to make virgin polyester.

Abstract: There is described a process for depolymerizing polyethylene naphthalate polyester to monomer components which then can be used to make virgin polyester.

Abstract: A method of removing dimethyl terephthalate (DMT) from a vapor stream. The vapor stream includes dimethyl terephthalate (DMT), methylhydroxyethyl terephthalate (MHET), glycols and methanol. A distillation column is held under an elevated pressure of 100 to 500 kPag and at a temperature of at least 85.degree. C. It has (i) a plurality of distillation trays; (ii) methanol liquid sprays between the trays; (iii) a main spray zone below the trays and (iv) a liquid pool of methanol in the bottom of the column. The vapor stream is directed into the distillation column, above the liquid pool and below the main spray zone, thereby forming a stream of liquid and vapor. The stream of liquid is directed away from the distillation column walls and into the liquid pool at the bottom of the column.

Abstract: There is described a process for the depolymerization of polyethylene terephthalate into component monomers using a reactor in which the polyethylene terephthalate is a discontinuous phase which contacts a continuous phase of superheated methanol vapor.

Abstract: There is described a process and optimal conditions for depolymerizing polyester into its components and separating the components using apparatus comprising:a dissolver for receiving polyester,a reactor for depolymerizing polyester into components, anda rectifier for separating polyester components; the process comprising the steps of:a) adding polyester to the dissolver and combining it with melt from the reactor and liquid from the rectifier to reduce the chain length of the polyester,b) transferring reduced chain length polyester from the dissolver to the reactor,c) passing super-heated methanol through the reactor to depolymerize polyester into its constituent monomers;d) transferring depolymerization products from the reactor to the rectifier; ande) separating the depolymerization products in the rectifier into a vapor phase containing component monomers and a liquid phase containing higher molecular weight materials.

Abstract: A silver nitrate feed solution containing nitrites and nitric acid is treated to produce a low-nitrite silver nitrate product solution. In the process, the temperature of the feed solution is established in the range of from about 80.degree. C. to about the boiling point of the feed solution. The feed solution is introduced into a vessel having a stripping zone containing a contacting element and is dispersed over the contacting element. The feed solution is flowed counter to and intimately contacted in the stripping zone with a motive gas to strip nitrites from solution and form a low-nitrite silver nitrate product solution.

Abstract: A process of recovering components such as ethylene glycol and dimethylterephthalate from scrap polyester. The process steps are: (a) introducing oligomers of ethylene glycol and terephthalate acid or dimethyl terephthalate to a first vessel and heating the oligomers; (b) introducing scrap polyester to the first vessel and forming a startup melt with the oligomers; (c) transferring melt from the first vessel to a second vessel; (d) passing super-heated methanol through the melt in the second vessel to form a final melt comprising low molecular weight polyesters and monomers; (e) transferring final melt from the second vessel to the first vessel; and (f) recovering components from the second vessel.

Abstract: A method of recovering ethylene glycol and dimethyl terephthalate from scrap polyethylene terephthalate resins by dissolving the scrap in oligomers of the same monomers and passing methanol through the solution.