To improve yield of monomers. A monomer production system includes a dissolving unit that stores therein a polyester solution, a first reaction unit into which the polyester solution and a reaction solvent are introduced and that depolymerizes the polyester in the polyester solution and extracts a first depolymerized polyester containing the depolymerized polyester into the reaction solvent, a second reaction unit that further depolymerizes the first depolymerized polyester and generates a second depolymerized polyester that is the further depolymerized first depolymerized polyester, a separation unit that separates the reaction solvent in which the second depolymerized polyester is dissolved into the reaction solvent, a carboxylic acid-derived monomer, an alcohol component monomer, and residual substances that are components other than the reaction solvent, the carboxylic acid-derived monomer, and the alcohol component monomer, and contain oligomers, and inlet pipes that introduce the carboxylic acid-derived monomer and the residual substances into the dissolving unit.

To improve yield of monomers. A monomer production system includes a dissolving unit that stores therein a polyester solution, a first reaction unit into which the polyester solution and a reaction solvent are introduced and that depolymerizes the polyester in the polyester solution and extracts a first depolymerized polyester containing the depolymerized polyester into the reaction solvent, a second reaction unit that further depolymerizes the first depolymerized polyester and generates a second depolymerized polyester that is the further depolymerized first depolymerized polyester, a separation unit that separates the reaction solvent in which the second depolymerized polyester is dissolved into the reaction solvent, a carboxylic acid-derived monomer, an alcohol component monomer, and residual substances that are components other than the reaction solvent, the carboxylic acid-derived monomer, and the alcohol component monomer, and contain oligomers, and inlet pipes that introduce the carboxylic acid-derived monomer and the residual substances into the dissolving unit.

To improve yield of monomers. A monomer production system includes a dissolving unit that stores therein a polyester solution, a first reaction unit into which the polyester solution and a reaction solvent are introduced and that depolymerizes the polyester in the polyester solution and extracts a first depolymerized polyester containing the depolymerized polyester into the reaction solvent, a second reaction unit that further depolymerizes the first depolymerized polyester and generates a second depolymerized polyester that is the further depolymerized first depolymerized polyester, a separation unit that separates the reaction solvent in which the second depolymerized polyester is dissolved into the reaction solvent, a carboxylic acid-derived monomer, an alcohol component monomer, and residual substances that are components other than the reaction solvent, the carboxylic acid-derived monomer, and the alcohol component monomer, and contain oligomers, and inlet pipes that introduce the carboxylic acid-derived monomer and the residual substances into the dissolving unit.

The present disclosure relates to a recycling method for producing dimethyl carbonate and dimethyl carbonate derivatives. The process is unique in that it produces a by-product that can be re-used in the process as a raw material for repeating the process. For example, when the process is directed to synthesizing dimethyl carbonate, glycerol is used as a starting material. Glycerol is also a by-product produced during formation of dimethyl carbonate, and therefore it can be re-used as starting material to generate more dimethyl carbonate.

The present disclosure relates to a recycling method for producing dimethyl carbonate and dimethyl carbonate derivatives. The process is unique in that it produces a by-product that can be re-used in the process as a raw material for repeating the process. For example, when the process is directed to synthesizing dimethyl carbonate, glycerol is used as a starting material. Glycerol is also a by-product produced during formation of dimethyl carbonate, and therefore it can be re-used as starting material to generate more dimethyl carbonate.

The present disclosure relates to a recycling method for producing dimethyl carbonate and dimethyl carbonate derivatives. The process is unique in that it produces a by-product that can be re-used in the process as a raw material for repeating the process. For example, when the process is directed to synthesizing dimethyl carbonate, glycerol is used as a starting material. Glycerol is also a by-product produced during formation of dimethyl carbonate, and therefore it can be re-used as starting material to generate more dimethyl carbonate.

The present invention relates to the depolymerization of polymers and the recovery of the starting materials used for the production of the polymer. The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of terephthalic acid and ethylene glycol.

The present invention provides a method for directly preparing glycol dimethyl ether and co-producing ethylene glycol from ethylene glycol monomethyl ether. More specifically, the method comprises passing a feedstock containing a raw material of ethylene glycol monomethyl ether and a carrier gas through a reactor loaded with a solid acid catalyst to produce glycol dimethyl ether and ethylene glycol, at a reaction temperature range from 40 C. to 150 C. and a reaction pressure range from 0.1 MPa to 15.0 MPa; wherein a carrier gas is an optional inactive gas; and the feedstock contains water whose volume concentration in the feedstock is in a range from 0% to 95%; and the weight hourly space velocity of the raw material of ethylene glycol monomethyl ether is in a range from 0.05 h.sup.1 to 5.0 h.sup.1; and the volume concentration of the raw material of ethylene glycol monomethyl ether in the feedstock is in a range from 1% to 100%; and the volume concentration of the carrier gas in the feedstock is in a range from 0% to 99%. In the method of the present invention, using a solid acid as a catalyst and ethylene glycol monomethyl ether as a raw material, under a low temperature condition, glycol dimethyl ether and ethylene glycol are prepared directly with high selectivity; moreover, there is substantially or completely no production of by-product 1,4-dioxane that causes pollution to the environment and is harmful to the human body or animal bodies.

The present invention provides a method for directly preparing glycol dimethyl ether and co-producing ethylene glycol from ethylene glycol monomethyl ether. More specifically, the method comprises passing a feedstock containing a raw material of ethylene glycol monomethyl ether and a carrier gas through a reactor loaded with a solid acid catalyst to produce glycol dimethyl ether and ethylene glycol, at a reaction temperature range from 40 C. to 150 C. and a reaction pressure range from 0.1 MPa to 15.0 MPa; wherein a carrier gas is an optional inactive gas; and the feedstock contains water whose volume concentration in the feedstock is in a range from 0% to 95%; and the weight hourly space velocity of the raw material of ethylene glycol monomethyl ether is in a range from 0.05 h.sup.1 to 5.0 h.sup.1; and the volume concentration of the raw material of ethylene glycol monomethyl ether in the feedstock is in a range from 1% to 100%; and the volume concentration of the carrier gas in the feedstock is in a range from 0% to 99%. In the method of the present invention, using a solid acid as a catalyst and ethylene glycol monomethyl ether as a raw material, under a low temperature condition, glycol dimethyl ether and ethylene glycol are prepared directly with high selectivity; moreover, there is substantially or completely no production of by-product 1,4-dioxane that causes pollution to the environment and is harmful to the human body or animal bodies.

A method of preparing ortho-alkenyl and ortho-acetyl benzylic alcohols is disclosed.