Process for the preparation of alkylene glycol

1. A reactor for the preparation of an alkylene glycol from an alkylene oxide, comprising:

(a) a carboxylation zone comprising one or more inlets for liquid reagents comprising alkylene oxide, water, a homogeneous carboxylation catalyst and a homogenous hydrolysis catalyst, one or more inlets for carbon dioxide, one or more ejectors for mixing carbon dioxide with the liquid reagents, and one or more outlets for a reaction solution comprising alkylene carbonate, water, the homogeneous carboxylation catalyst and the homogeneous hydrolysis catalyst;

(b) a hydrolysis zone comprising one or more inlets for the reaction solution, one or more outlets for carbon dioxide, and one or more outlets for a product solution comprising alkylene glycol, the homogeneous carboxylation catalyst and the homogeneous hydrolysis catalyst; and

(c) a channel whereby carbon dioxide can be supplied from the hydrolysis zone to the carboxylation zone,

wherein the carboxylation zone and the hydrolysis zone are contained within one reactor vessel and wherein the carboxylation zone is separated from the hydrolysis zone by an internal baffle.

2. A reactor according to claim 1 , wherein the single reactor vessel is divided into at least four compartments by internal baffles.

3. A reactor according to claim 1 , wherein the reactor comprises at least one recycle loop whereby liquid reagents are withdrawn from the carboxylation zone and subsequently returned to the carboxylation zone.

4. A reactor according to claim 1 , wherein carbon dioxide is supplied from the hydrolysis zone to the carboxylation zone without passing through a gas compressor.

5. A reactor according to claim 1 , wherein the hydrolysis zone comprises one or more inlets whereby steam is supplied to the hydrolysis zone, and the hydrolysis zone comprises one or more inlets whereby carboxylation catalyst and hydrolysis catalyst (in addition to the catalysts supplied in the reaction solution) are supplied to the hydrolysis zone.

6. A reactor according to claim 1 , wherein either the carboxylation zone or the hydrolysis zone has an inerts vent whereby gases are withdrawn.

7. A reactor according to claim 1 , wherein carbon dioxide is supplied from the hydrolysis zone to the carboxylation zone via an opening in a baffle separating the gas phase of the carboxylation zone from the gas phase of the hydrolysis zone, or wherein carbon dioxide is supplied from the hydrolysis zone to the carboxylation zone via external piping connecting the hydrolysis zone and the carboxylation zone.

8. A reactor according to claim 1 , wherein the carboxylation and hydrolysis catalysts are separated from the product stream by subjecting the product stream to a flash step in a flash vessel and a solution of the carboxylation and hydrolysis catalysts is recycled and supplied to the carboxylation zone.