WO2009103682A1

WO2009103682A1 - The catalyst and method of catalytic reduction of esters of hydroxycarboxylic acid to glycols

Info

Publication number: WO2009103682A1
Application number: PCT/EP2009/051794
Authority: WO
Inventors: Irina Leonidovna Simakova; Mikhail Nikolaevich Simonov; Margarita Petrovna Demeshkina; Tatyana Petrovna Minyukova; Alexandr Alexandrovich Khasin; Valentin Nikolaevich Parmon
Original assignee: Nordbiochem OÜ
Priority date: 2008-02-21
Filing date: 2009-02-16
Publication date: 2009-08-27
Also published as: EE200800009A

Abstract

The catalyst and method for catalytic reduction of esters of hydroxycarboxylic acids to glycols is disclosed. Esters of hydroxycarboxylic acids are contacted with hydrogen in gas phase at the presence of catalyst which contains mixture of copper and/or oxide of copper and/or hydroxide of copper and/or salt or mixture of salts of copper and of inorganic acids of the element IVb, Va and VIa groups of periodic system, and oxide or mixture of oxides of elements of IVb, Va and VIa groups of periodic system. The process of reduction of esters of hydroxycarboxylic acids to glycols is carried out at hydrogen pressures of less than 10 atm and temperature between 140 and 22O°C.

Description

The catalyst and method of catalytic reduction of esters of hydroxycarboxylic acid to glycols

FIELD OF THE INVENTION

The present invention relates to a process for the production of diols with high yield and selectivity by hydrogenation of hydroxycarboxylic acid esters in gas phase over copper containing catalysts. In particular, the present invention relates to a process for the production of ethylene and propylene glycols.

DESCRIPTION OF RELATED ART

The ethylene and propylene glycols are used in a wide variety of applications such as monomers in polyester resins; in antifreeze and de-icing fluids; in the manufacture of food, drugs and cosmetic products; and in liquid detergents. Commercial production of glycols is currently petroleum-based and involves the high pressure and high temperature hydrolysis of alkylene oxides.

Since this process starts with ethylene and propylene, the price of the resulting 1 ,2-diols depends on the change in the price of oil and other hydrocarbon. The new method is demanded to produce glycols from renewable resources such as plants.

It is well known that plants produce carbohydrates from atmospheric carbon dioxide and sunlight in the process of photosynthesis. Furthermore, as carbon dioxide is a greenhouse gas, so any additional removal of the gas from the atmosphere helps to offset the increase in this gas by industrial emissions. The method based on hydroxycarboxylic acids obtained by fermentation of crude biomass is promising way for glycols production (WO 2000030744, US 6455742, US 6479713).

It is known that liquid-phase hydrogenation of carboxyl groups occurs under high hydrogen pressure. To perform the hydrogenation process under milder conditions carboxylic acids are usually converted into more readily reducible esters. Various patents and articles disclose the reduction of hydroxycarboxylic acid esters. For example, the hydrogenation of organic esters to alcohols and glycols in a liquid phase was reported by Adkins and co-workers who were able to achieve 80% yields of propylene glycol from methyl lactate over copper/chromium oxide and Raney nickel catalysts at temperature from 150° to 25O⁰C and extremely high hydrogen pressures from 20 to 30 MPa (Bowden and Adkins, J. Am. Chem. Soc. 56: 689 (1934); Adkins and Billica, J. Am. Chem. Soc. 70: 3118 (1948); Adkins and Billica, J. Am. Chem Soc. 70: 3121 (1948)).

In addition to high pressure high catalyst loading is necessary to achieve these relatively high yields. Broadbent et al. (J. Org. Chem. 24: 1847 (1959)) was able to obtain propylene glycol from ethyl lactate over ruhenium black catalysts with yield as high as 80% at 15O⁰C but at very high hydrogen pressure about 25 MPa.

The hydrogenation of organic esters to glycols in a liquid phase was reported by Luo and co-workers who have achieved 83% yield of propylene glycol from ethyl lactate over Ru- Sn/γ-Al₂O₃ at 15O⁰C and 5.5 MPa. (Luo, G., Yan, S., Qiao, M., Zhuang, J., Fan, K. Appl. Catal. A. 275: 95 (2004)).

The serious disadvantage of all mentioned processes of a liquid phase hydrogenation is necessity to use a high hydrogen pressure.

Carrying out the process of hydrogenation in a vapor phase allows lowering hydrogen pressure. For example, the hydrogenation of organic esters to alcohols and glycols in a vapor phase over copper-zinc oxides catalysts at 234⁰C, 1.6 MPa and LHSV=I.06 h^"1 was reported by Bradley and co-workers (Pat. WO8203854, 1982) who have achieved 97.7% selectivity to propylene glycol and 34.7 % conversion of ethyl lactate. The specific capacity of the catalyst is 0.038 g of propylene glycol /(ml of catalyst*h).

Despite these efforts, a need for new methods of production of glycols remains that can be performed under relatively mild conditions and which results in high conversion of esters, selectivity to glycols and specific capacity of the catalyst.

SUMMARY OF THE INVENTION

The present invention provides a process for the low-cost, bulk production of glycols from esters of hydroxycarboxylic acid under relatively mild conditions with high conversion of esters, selectivity to glycols and specific capacity of the catalyst. In more detail, the present invention provides a process for the production of glycols, which comprises: reacting a mixture of esters of hydroxycarboxylic acid and hydrogen in gas phase at presence of the catalyst which contains mixture of copper and/or oxide of copper and/or hydroxide of copper and/or salt or mixture of salts of copper and of inorganic acids of the element IVb, Va and Via groups of periodic system, and oxide or mixture of oxides of the element of IVb, Va and Via groups of periodic system.

Catalyst can be prepared by the reductive thermal treatment of the composition, which contains salt or mixture of salts of copper and of inorganic acids of the element IVb, Va and Via groups of periodic system and/or mixture of oxide and/or hydroxide of copper and oxides and/or hydroxides of the elements of IVb, Va and Via groups of periodic system at flow of hydrogen and high temperature (preferable, at temperature between about 350 to 500⁰C within 1-6 hour). As a result the catalysts have been obtained which contain various amount of copper and oxide of copper (preferable 14-50% wt. of copper and 1-15% wt. oxide of copper).

For the illustration of the method the esters of aliphatic alcohols and lactic and glycolic acids were used as esters of hydroxycarboxylic acid in order to obtain propylene and ethylene glycols correspondingly.

EXAMPLES

Example 1

The catalyst was prepared by reductive thermal decomposition of mixture of copper silicate (95 %wt.) and copper molybdate (5 %wt.) under flow of hydrogen and temperature about 500⁰C within 1 hour. As a result the catalyst which contains 47 %wt. of copper and 4 %wt of copper oxide has been obtained. Copper silicate, copper molybdate, molybdenum oxide and silica - the rest.

0.45 g of 0.3-0.5 mm fraction of the catalyst was mixed with 0,45 g and 0.8-1.0 mm fraction of quartz glass and was loaded into the quartz tube U-shaped reactor.

Methyl lactate heated up to temperature of 185⁰C and hydrogen were fed to mixer with flow rate 0.4 ml/hour and 9 I/hour accordingly. Resulting gaseous mixture of hydrogen and methyl lactate were supplied into reactor. Temperature in the reactor was maintained at about 200⁰C. The pressure - 1 atm. Process was carried out within five hours. The products of the reaction were condensed and the condensate was analyzed. The condensate has the following composition, %wt.: methyl lactate - 8.5; methanol - 3.3; l-hydroxy-2- propanone - 13.0; propylene glycol - 71.3; unidentified by-products - 3.9. The conversion of methyl lactate was 87 %mol., selectivity to propylene glycol was 89 %mol. The specific capacity of the catalyst (g glycol/g catalyst/hour) was 0.56.

Even in 100 hours after starting of the process, the selectivity to propylene glycol was

88%.

Example 2-7

Processes were performed similarly to an example 1 with various catalysts and under various conditions.

Precursors for preparation of the catalysts, conditions of synthesis of the catalysts, contents of copper and oxides of copper in prepared catalysts are shown in Table 1. Conditions and results of hydrogenation in the presence of the given catalysts are shown in Table 2.

Table 1. Conditions of preparation of catalysts

Notes:

- In parentheses: the value of selectivity obtained after 100 hours of continuous process.

Claims

1. The catalyst for catalytic reduction of esters of hydroxycarboxylic acid to glycols, wherein the catalyst contains mixture of copper and/or oxide of copper and/or hydroxide of copper and/or salt or mixture of salts of copper and of inorganic acids of the element IVb, Va and Via groups of periodic system, and oxide or mixture of oxides of elements of IVb, Va and Via groups of periodic system.

2. The catalyst for catalytic reduction of esters of hydroxycarboxylic acid to glycols according to claim 1, wherein the catalyst contains 14-50% wt. of copper.

3. The method for preparation of the catalyst according to claim 1, wherein the catalyst is prepared by reductive thermal treatment of the composition, which contains of salt or mixture of salts of copper and of inorganic acids of the element IVB, Va and Via groups of periodic system and/or mixture of oxide and/or hydroxide of copper and oxides and/or hydroxides of the elements of IVb, Va and Via groups of periodic system.

4. The method of catalytic reduction of esters of hydroxycarboxylic acid to glycols, comprising contact of esters of hydroxycarboxylic acids with hydrogen in gas phase, wherein the process is carried out at presence of the catalyst according to claim 1.

5. The method according to claim 4, wherein the processes is carried out at pressure below 10 bar and temperature between 140 and 22O⁰C.

6. The method according to claim 4, wherein the processes is carried out at temperature between 180 and 200⁰C.