The present disclosure relates to the formation of dimethyl terephthalate (DMT). The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of dimethyl terephthalate (DMT).

The present disclosure relates to the formation of dimethyl terephthalate (DMT). The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of dimethyl terephthalate (DMT).

A process for preparing metal alkoxides by transalcoholisation, comprising: feeding a lower metal alkoxide and a higher alcohol into a reactive distillation column; removing a solution of a higher metal alkoxide in the higher alcohol from the bottom of the column or from a recycle stream taken from the bottom of the column; and removing a gaseous lower alcohol from the top of the column, at least partially condensing the gaseous lower alcohol, and recirculating a part of the condensate to the top of the column; wherein an auxiliary alcohol is provided in the reactive distillation column, the boiling point of the auxiliary alcohol being between the boiling point of the lower alcohol and the boiling point of the higher alcohol at the pressure prevailing in the reactive distillation column. The process allows for high conversion of a lower metal alkoxide to a higher metal alkoxide while limiting the formation of solid deposits in the column, while having low energy requirements.

The present disclosure relates to the formation of dimethyl terephthalate (DMT). The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of dimethyl terephthalate (DMT).

The present disclosure relates to the formation of dimethyl terephthalate (DMT). The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of dimethyl terephthalate (DMT).

There is provided a novel alkoxymagnesium which, when used as a constituent of a solid catalyst component for olefin polymerization to polymerize an olefin, may reduce the formation rate of a fine powder and may form a polymer having an excellent particle size distribution under high polymerization activity. The alkoxymagnesium is characterized by comprising secondary particles each of which is an aggregate of primary particles having an average particle diameter of less than 1 m and by having a ratio represented by the average particle diameter of the primary particles/the average particle diameter of the secondary particles of 0.1 or less, a total pore volume of 0.5 to 1 cm.sup.3/g, a specific surface area of less than 50 m.sup.2/g, and a particle size distribution index (SPAN) 1 or less.

There is provided a novel alkoxymagnesium which, when used as a constituent of a solid catalyst component for olefin polymerization to polymerize an olefin, may reduce the formation rate of a fine powder and may form a polymer having an excellent particle size distribution under high polymerization activity. The alkoxymagnesium is characterized by comprising secondary particles each of which is an aggregate of primary particles having an average particle diameter of less than 1 m and by having a ratio represented by the average particle diameter of the primary particles/the average particle diameter of the secondary particles of 0.1 or less, a total pore volume of 0.5 to 1 cm.sup.3/g, a specific surface area of less than 50 m.sup.2/g, and a particle size distribution index (SPAN) 1 or less.

The invention relates to hydrocarbon-soluble halogen or thiolate/magnesium exchange reagents of the general formula

R.sup.1MgR.sup.1.sub.1n(OR.sup.3).sub.n.Math.LiOR2.Math.(1n)LiOR.sup.3.Math.aDonor

in which: R.sup.1 is a C1-C8 alkyl and OR.sup.2 as well as OR.sup.3 are same or different and represent primary, secondary, or tertiary alkoxide residues having 3 to 18 carbon atoms, wherein R.sup.2 and/or R.sup.3 can for their part contain an alkoxy substituent OR.sup.4; a assumes a value of 0 to 2, n assumes a value between 0 and 1, and the donor is an organic molecule containing at least 2 nitrogen atoms.

A method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme A: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the feed amount of the reactant alcohol; Scheme B: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the heat supplied to the bottom of the reactive distillation column. The invention also relates to a method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; causing an auxiliary alcohol to be present in the reactive distillation column; and optionally replenishing the auxiliary alcohol via a side feed located above the feed of the reactant alcohol and below the top of the column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme C: establishing a signal S2 which is responsive to a temperature at a point located between the feed of the metal methoxide and the bottom of the reactive distillation column; and manipulating in response to the signal S2 the feed amount of the reactant alcohol; Scheme D: establishing a signal S2 which is responsive to a temperature at a point located between the feed of the metal methoxide and the bottom of the reactive distillation column; and manipulating in response to the signal S2 the heat supplied to the bottom of the reactive distillation column. The methods of the invention allow for improved controlling of a reactive distillation column for effecting a transalcoholisation reaction.

One or more concentrated low-viscosity solutions of alkaline earth alkoxide compounds M(OCH.sub.2R.sup.6).sub.2-a-b(OR.sup.7).sub.a[O(CHR.sup.8).sub.nOR.sup.9].sub.b in mixture with a metal alkyl compound M(R.sup.10R.sup.11) in an aprotic solvent and related methods are disclosed herein.