Disclosed is a method for treating the product stream from a polyester methanolysis depolymerization process wherein the product stream includes dimethyl terephthalate and one or more side species selected from the group consisting of dimethyl phthalate, dimethyl isophthalate, bisphenol-A, an adipic acid diester and colorants. The method includes a) hydrogenating said dimethyl terephthalate to form one or more of dimethyl 1,4-cyclohexanedicarboxylate and 1,4-cyclohexanedimethanol; and (b) hydrogenating one or more of said one or more side species of said product stream. A method for depolymerization of polyester is also described.

Disclosed is a method for treating the product stream from a polyester methanolysis depolymerization process wherein the product stream includes dimethyl terephthalate and one or more side species selected from the group consisting of dimethyl phthalate, dimethyl isophthalate, bisphenol-A, an adipic acid diester and colorants. The method includes a) hydrogenating said dimethyl terephthalate to form one or more of dimethyl 1,4-cyclohexanedicarboxylate and 1,4-cyclohexanedimethanol; and (b) hydrogenating one or more of said one or more side species of said product stream. A method for depolymerization of polyester is also described.

Disclosed is a method for depolymerization of polyester. The method includes (a) treating said polyester with methanol under conditions sufficient to depolymerize at least some of said polyester and form a reaction product that includes dimethyl terephthalate and at least one diol; and (b) converting the diol to a compound substantially non-reactive with said with dimethyl terephthalate and the polyester. A method for producing a cyclic carbonate is also described.

Disclosed is a method for depolymerization of polyester. The method includes (a) treating said polyester with methanol under conditions sufficient to depolymerize at least some of said polyester and form a reaction product that includes dimethyl terephthalate and at least one diol; and (b) converting the diol to a compound substantially non-reactive with said with dimethyl terephthalate and the polyester. A method for producing a cyclic carbonate is also described.

A novel process can be used for purifying methyl methacrylate (MMA) contaminated with low-boiling components by distillation, where the process involves producing MMA by oxidative esterification, and a crude product containing methyl propionate (MP), methyl isobutyrate (MIB), and methacrolein (MAL) as low-boiling components. The process is compatible with MMA produced from C.sub.2-based methacrolein containing the low-boiling components specified.

A novel process can be used for purifying methyl methacrylate (MMA) contaminated with low-boiling components by distillation, where the process involves producing MMA by oxidative esterification, and a crude product containing methyl propionate (MP), methyl isobutyrate (MIB), and methacrolein (MAL) as low-boiling components. The process is compatible with MMA produced from C.sub.2-based methacrolein containing the low-boiling components specified.

Process for purifying bis(2-hydroxyethyl)terephthalate (BHET) obtained from depolymerization of a polyethylene terephthalate (PET) waste, the process comprising: treating said solution with at least one oxidizing agent at a temperature of from 30° C. to 100° C., preferably from 50° C. to 90° C., to obtain an oxidized solution; treating the oxidized solution with at least one adsorbing agent to obtain a purified oxidized solution; separating the at least one adsorbing agent from the purified oxidized solution to obtain a purified BHET solution. This process is particularly effective for eliminating organic dyes and other low molecular weight organic contaminants, so as to achieve a high purity degree of the recovered BHET.

Process for purifying bis(2-hydroxyethyl)terephthalate (BHET) obtained from depolymerization of a polyethylene terephthalate (PET) waste, the process comprising: treating said solution with at least one oxidizing agent at a temperature of from 30° C. to 100° C., preferably from 50° C. to 90° C., to obtain an oxidized solution; treating the oxidized solution with at least one adsorbing agent to obtain a purified oxidized solution; separating the at least one adsorbing agent from the purified oxidized solution to obtain a purified BHET solution. This process is particularly effective for eliminating organic dyes and other low molecular weight organic contaminants, so as to achieve a high purity degree of the recovered BHET.

Process for purifying bis(2-hydroxyethyl)terephthalate (BHET) obtained from depolymerization of a polyethylene terephthalate (PET) waste, the process comprising: treating said solution with at least one oxidizing agent at a temperature of from 30° C. to 100° C., preferably from 50° C. to 90° C., to obtain an oxidized solution; treating the oxidized solution with at least one adsorbing agent to obtain a purified oxidized solution; separating the at least one adsorbing agent from the purified oxidized solution to obtain a purified BHET solution. This process is particularly effective for eliminating organic dyes and other low molecular weight organic contaminants, so as to achieve a high purity degree of the recovered BHET.

A process for obtaining product streams enriched with polyol esters from the secondary streams from polyol ester preparation, comprising a) the reaction of polyols of the general formula (II)
H—(—O—[—CR.sup.1R.sup.2—].sub.m—).sub.o—OH  (II) in which R.sup.1 and R.sup.2 are each independently hydrogen, an alkyl radical having 1 to 5 carbon atoms or a hydroxyalkyl radical having 1 to 5 carbon atoms, m is an integer from 1 to 10, o is an integer from 2 to 15, with linear or branched aliphatic monocarboxylic acids having 3 to 20 carbon atom, with removal of the water formed; b) the removal of unconverted starting compounds from the crude ester formed; c) the treatment of the crude ester obtained in step b) with steam to form a volatile secondary stream; and d) the removal of the volatile secondary stream obtained in step c), characterized in that the volatile secondary stream obtained in step d) is separated into an aqueous phase and an organic phase and the organic phase removed is subjected to a further treatment with steam and a product stream enriched with polyol esters is obtained as residue.