EP3645487A1

EP3645487A1 - Process for the manufacture of ethylene glycol

Info

Publication number: EP3645487A1
Application number: EP17916114.6A
Authority: EP
Inventors: Peng Wu; Frédérique DESMEDT; Pierre Dournel; Armin T. Liebens
Original assignee: Solvay SA; East China Normal University
Current assignee: Solvay SA; East China Normal University
Priority date: 2017-06-28
Filing date: 2017-06-28
Publication date: 2020-05-06
Also published as: WO2019000281A1; EP3645487A4

Abstract

L'invention concerne un procédé de fabrication d'éthylène glycol à partir d'éthylène (Ee), ledit procédé utilisant un mélange de réaction comprenant du Ee, un catalyseur zéolite Ti-MWW, du peroxyde d'hydrogène et de l'eau, ledit mélange de réaction contenant en outre un stabilisant du peroxyde d'hydrogène.The invention relates to a process for producing ethylene glycol from ethylene (Ee), said process using a reaction mixture comprising Ee, a zeolite Ti-MWW catalyst, hydrogen peroxide and water, said reaction mixture further containing a hydrogen peroxide stabilizer.

Description

Process for the manufacture of ethylene glycol

The present invention relates to a process for the manufacture of ethylene glycol starting from ethylene (Ee) .
Ethylene Glycol (Mono-Ethylene Glycol or MEG) is an important organic chemical raw material mainly used in the production of polyester (more precisely of PET or poly-ethylene-terephthalate) and as antifreeze agent.
At present, large-scale ethylene glycol production is generally made using a non-catalytic direct hydration method wherein ethylene oxide (EO) and water are reacted generally in a molar ratio of about 1: 20-22 (molar ratio) resulting in an ethylene glycol aqueous solution containing only about 10％ (mass fraction) of MEG, the rest being water and by-products like diethylene glycol (DEG) and triethylene glycol (TEG) . Increasing the amount of water used for this method can reduce the by-product formation and improve the conversion rate of ethylene oxide. However, it makes it necessary to set up multiple evaporators/distillation columns, increasing the equipment investment and energy consumption, which directly affects the production cost of ethylene glycol.
An advantage of the direct synthesis of MEG starting from Ee instead of EO, lies in the fact that EO, which is the intermediary resulting from the oxidation of Ee in EO with the peroxide, is not isolated or purified but consumed very fast in a hydrolysis reaction. EO is indeed a highly explosive compound having besides a high toxicity level (1.15 mg/m3) .
CN105001058 discloses the use of Al modified Ti-MWW zeolite catalyst for the manufacturing MEG directly from Ee, in one step, using water as solvent and hydrogen peroxide as oxidizing agent.
The inventors have now discovered that it is in fact not necessary to modify the Ti-MWW catalyst, which is well known, but that merely putting a given additive in the reaction medium can increase the efficiency of the one step reaction.
By adding nitric acid or HEDP to the water, the inventors were namely able to increase the hydrogen peroxide efficiency from 30％to 69％in the best case for HEDP and to 67％in the case of nitric acid. Generally, acidity in presence of an epoxide speeds up the ring opening but increases the oligomerisation of the diols too.
Quite surprisingly, in the present case, the inventors didn’ t observe any loss in MEG selectivity in presence of either nitric acid or HEDP.
Therefore, the present invention relates to a process for the manufacture of ethylene glycol starting ethylene (Ee) , said process using a reaction mixture comprising Ee, a Ti-MWW zeolite catalyst, hydrogen peroxide and water, said reaction mixture containing additionally a hydrogen peroxide stabilizer.
In one embodiment, the hydrogen peroxide stabilizer is a mineral acid, preferably nitric acid.
In another embodiment, compatible with the first one, the hydrogen peroxide stabilizer is HEDP (1-hydroxy ethylidene-1, 1-diphosphonic acid) .
Preferred embodiments of the invention are those according to which:
-the Ti-MWW zeolite is modified with an organic amine, preferably with an aqueous solution of piperidine or hexamethyleneimine；
-the catalyst concentration in the reaction mixture is in the range of from 0.5 to 5 wt. ％；
-the process is performed at a temperature from 20℃ to 150℃；
-the molar ratio of hydrogen peroxide to Ee is in the range of from 0.01 to 10；
-the molar ratio of water to Ee is in the range of from 1 to 50；
-the molar ratio between water and hydrogen peroxide is in the range of from 5 to 50.
Considering the fact that Ee-oxygen mixtures can be explosive, care should be taken to work in conditions outside the explosion zone.
In the invention, the catalyst is preferably used as a slurry catalyst or a fixed bed catalyst. Hence, the zeolite is preferably mixed with a binder like silica, alumina or a mixture thereof and then shaped for instance by extrusion.
The following Examples illustrate some embodiments of the present invention. In these Examples, the following instructions were applied:
-In a reactor, introduce 1g of TiMWW, 150g of DMW (demin. Water) and nitric acid or HEDP, the case being, in order to obtain the desired concentration.
-Close the reactor and purge it under nitrogen.
-Increase the pressure up to 25 bar under constant flow of nitrogen and start to heat the reactor at 70℃.
-When the temperature is reached, start the ethylene flow at 3, 33 g/min and stop the nitrogen flow.
-Follow by gas Phase Chromatography the disappearing of the nitrogen.
-When the N2 peak is no more visible, start the mechanical stirrer (1200 rpm) and start to feed the reactor with hydrogen peroxide (35％Wt. -0, 5 g/min) .
-Follow the hydrogen peroxide consumption by titration with cerium sulfate.
-Check the concentration in MEG, DEG and TEG by GC.
The results obtained in these Examples are shown in Table 1 below.
The calculations were performed as follows:
H2O2 conversion ＝ 1- ( (N mol H2O2 residual) / (N mol H2O2 total fed))
H2O2 Efficiency ＝ (N mol H2O2 converted into MEG, DEG and TEG) / (N mol H2O2 total fed)
MEG Selectivity ＝ (N mol MEG produced) / (N mol (MEG + DEG + TEG + NI))
Table 1.

Claims

A process for the manufacture of ethylene glycol starting ethylene (Ee) , said process using a reaction mixture comprising Ee, a Ti-MWW zeolite catalyst, hydrogen peroxide and water, said reaction mixture containing additionally a hydrogen peroxide stabilizer.
The process according to the preceding claim, wherein the hydrogen peroxide stabilizer is a mineral acid.
The process according to the preceding claim, wherein the mineral acid is nitric acid.
The process according to claim 1, wherein the hydrogen peroxide stabilizer is HEDP (1-hydroxy ethylidene-1, 1-diphosphonic acid) .
The process according to any of the preceding claims, wherein the Ti-MWW zeolite is modified with an organic amine.
The process according to the preceding claim, wherein the organic amine is piperidine or hexamethyleneimine .
The process according to any of the preceding claims, wherein the catalyst concentration in the reaction mixture is in the range of from 0.5 to 5 wt. ％.
The process according to any of the preceding claims, wherein the process is performed at a temperature from 20℃ to 150℃.
The process according to any of the preceding claims, wherein the molar ratio of water to Ee is in the range of from 1 to 50.
The process according to any of the preceding claims, wherein the molar ratio of hydrogen peroxide to Ee is in the range of from 0.01 to 10.
The process according to any of the preceding claims, wherein the catalyst is a slurry catalyst or a fixed bed catalyst.
The process according to the preceding claim, wherein the zeolite is mixed with a binder like silica, alumina or a mixture thereof and shaped by extrusion.