A method for the preparation of 1,2-propanediol

2:

• The method of claim 1, wherein a) to d) are carried out continuously.

3:

• The method of claim 2, wherein a), a concentration of the hydrogen peroxide in the aqueous phase is from 0.1 to 5% by weight.

4:

• The method of claim 1, wherein a molar ratio of the propene introduced to a) to the hydrogen peroxide introduced to a) is from 1.2:1 to 5:1.

5:

• The method of claim 1, wherein the alkylaromatic hydrocarbon solvent comprises more than 50 by weight of at least one alleviated aromatic hydrocarbon having from 7 to 12 carbon atoms.

6:

• The method of claim 1, wherein in c), the non-flammable gas is passed through the organic phase (Po).

7:

• The method of claim 1, wherein in c), the desorption is carried out with counter current flow of the non-flammable gas and the organic phase (Po).

8:

• The method of claim 1, wherein in c), the flow rate of the non-flammable gas, the temperature, and the pressure are adjusted to provide an oxygen concentration in the off-gas of from 1 to 11 mol-%.

9:

• The method of claim 1, wherein nitrogen is used as the non-flammable gas.

10:

• The method of claim 1, wherein a) is carried out with a propene feedstock containing from 1 to 8 mol-% of propane, and
• wherein in c), the flow rate of the non-flammable gas, the temperature, and the pressure are adjusted to provide the off-gas with a mass ratio of propane to a combined amount of propane and propene of from 0.2 to 0.7.

11:

• The method of claim 1, wherein a) is conducted continuously in a loop reactor comprising fixed internals in a tubular section, and the liquid reaction mixture is passed through the loop reactor at a flow rate sufficient to provide turbulent flow at said fixed internals.

12:

• The method of claim 1, wherein the heteropolytungstate is a polytungstophosphate.

13:

• The method of claim 1, wherein the phase transfer catalyst is at least one selected from the group consisting of a tertiary amine, a tertiary ammonium salt, and a quaternary ammonium salt, and
• wherein the tertiary amine, the tertiary ammonium salt, and the quaternary ammonium salt each comprises in total at least 12 carbon atoms.

16:

• The facility of claim 15, wherein the phase separator comprises a phase boundary sensor controlling the first control valve, and the second control valve is a pressure retention valve.

17:

• The facility of claim 15, wherein the phase separator comprises a phase boundary sensor controlling the second control valve, and the first control valve is a pressure retention valve.

18:

• The facility of claim 15, wherein the separation unit comprises
• a first distillation column, the first distillation column having the inlet of said separation unit and a bottoms outlet, and
• a second distillation column, the second distillation column having an inlet connected to the bottoms outlet of the first distillation column, an overhead product outlet for the separated 1,2 propanediol and a bottoms outlet for the by-products.

19:

• The facility of claim 18, comprising a hydrogenation unit arranged between the first outlet of the phase separator and the inlet of the separation unit.

20:

• The facility of claim 15, further comprising a pressure retention valve ort the off-gas outlet of the oxygen desorption unit.