US-12624462-B2 - Process for preparing propylene and polypropylene from CO2

Abstract

Illustrative embodiment relates to an environmentally friendly process for producing propylene and its polymer propylene from the starting material carbon dioxide CO 2 .

Inventors

• Armin Aniol
• Fabian Fischer

Assignees

• VOLKSWAGEN AKTIENGESELLSCHAFT

Dates

Publication Date

20260512

Application Date

20230623

Priority Date

20220722

Claims (15)

1. 1 . A process for producing propylene (III) from CO 2 comprising: electrocatalytic reduction of the CO 2 to generate methylglyoxal (I); reduction of the methylglyoxal (I) in two stages, the first of which being carried out in an ethanolic solution and the second of which being carried out in an acidic solution, wherein the reduction is performed using sodium borohydride as a reducing agent to generate the corresponding 1,2-diol (II) to reduce both carbonyl groups of the methylglyoxal to hydroxyl groups; and elimination of the hydroxide groups of the 1,2-diol (II) to generate propylene (III) according to the following reaction equation: wherein the production of the propylene (III) from CO 2 is performed without replacement of the reducing agent and intermediate purification of monohydroxy intermediate thereby reducing necessary solvent and binding more atmospheric CO 2 than is released.
2. 2 . The process of claim 1 , wherein the electrocatalytic reduction employs a nickel phosphide catalyst.
3. 3 . The process of claim 1 , wherein the elimination employs a thiocarbonyl compound of formula Ila and/or a phosphorus compound selected from trimethyl phosphite, triethyl phosphite and the Corey-Hopkins reagent of formula IIb, where R 1 is selected from Cl and imidazole radicals.
4. 4 . The process of claim 1 , wherein the elimination is performed at 95° C. to 125° C.
5. 5 . The process of claim 1 , wherein the elimination employs, as a phosphorus compound, the Corey-Hopkins reagent of formula IIb:
6. 6 . The process of claim 1 , wherein the elimination is performed by potentiostatic electrolysis at ≤−1.0 V relative to Ag/AgCl.
7. 7 . The process of claim 1 , followed by polymerization of the propylene to generate polypropylene.
8. 8 . The process of claim 7 , wherein eliminated CO 2 is recycled for subsequent electrocatalytic reduction.
9. 9 . The process of claim 1 , wherein the elimination is performed at 100° C. to 120° C.
10. 10 . The process of claim 1 , wherein the elimination is performed at 105° C. to 115° C.
11. 11 . The process of claim 1 , wherein the elimination is performed by potentiostatic electrolysis at −1.9 to −1.0 V relative to Ag/AgCl.
12. 12 . The process of claim 1 , wherein the elimination is performed by potentiostatic electrolysis at −1.7 to −1.2 V relative to Ag/AgCl.
13. 13 . The process of claim 1 , wherein the elimination is performed by potentiostatic electrolysis at −1.5 to −1.4 V relative to Ag/AgCl.
14. 14 . The process of claim 1 , wherein the elimination is performed by potentiostatic electrolysis at −1.45 V, relative to Ag/AgCl.
15. 15 . A process for producing polypropylene including the process of claim 1 , wherein following the operations of the propylene generation process, the polypropylene production process includes polymerization of the propylene obtained to generate polypropylene.

Description

PRIORITY CLAIM This patent application is a U.S. National Phase of International Patent Application No. PCT/EP2023/067139, filed Jun. 23, 2023, which claims priority to German Patent Application No. 10 2022 207 521.8, filed Jul. 22, 2022, the disclosures of which are incorporated herein by reference in their entireties. SUMMARY Illustrative embodiments relate to an environmentally friendly process for producing propylene (i.e., propene) and its polymer polypropylene from the starting material carbon dioxide (CO2). DETAILED DESCRIPTION To improve the overall CO2 balance of industrial products, for example, of transportation vehicles, the use of sustainable materials is an effective lever. In this context, sustainable polymers are becoming increasingly important in large-volume industries, for example, in the transportation vehicle industry. The three most relevant raw material sources for sustainable polymers comprise renewable raw materials (bio-based approaches), recycled plastics and CO2 as the polymer raw material source. In terms of bio-based polymers from renewable raw materials the literature already discloses a number of polymers (PLA, PHB, etc.) which make it possible to minimize the CO2 footprint over the entire product life cycle compared to the petrochemical alternative. Increasing use is also being made of recycled plastics to minimize the CO2 footprint by a closed material circuit. However, these two polymer classes are not suitable for use in applications with demanding requirements, since it is not possible to achieve control of the molecular weight, and thus of the physical, mechanical and chemical properties, for the bio-based approaches and for the recycled plastics due to variations in the natural raw materials and due to degradation effects in the recycling process respectively. Calvinho et al. describe various nickel phosphides which make it possible to convert CO2 to C3-C4 compounds, such as 2,3-furandiol (C4) and the byproduct methylglyoxal (C3), in aqueous solution (Calvinho et al., Energy Environ. Sci., 2018, 11, 2550-2559). US 2020/0 347 502 A1 likewise describes nickel phosphides for electrochemical reduction of CO2 to hydrocarbons using nickel phosphide nanoparticles. It is possible, in turn, to produce various polymers from their associated alkenes, for example. Suitable starting materials for these alkenes include, for example, diols which react to generate the alkene by elimination. In this regard, Lopez et al. describes the electrochemical Corey-Winter elimination reaction with trimethyl phosphite or triethyl phosphite or the known Corey-Winter reagent (Lopez et al., Beilstein H. Org. Chem. 2018, 14, 547-552). The polymerization is effected by conventional industrial processes. Thus, for example, DE 3 703 038 A1 describes the production of branched low-pressure polyolefins having polyethene side chains, wherein polyethylene (PE) is produced from ethene using a nickel catalyst. A copolymer with short-chain α-olefins and a chromium catalyst is also disclosed. In terms of the approach of using CO2 as the main raw material for the alkene propylene or the corresponding polymer polypropylene, no industrially applicable processes have been disclosed to date. Accordingly, disclosed embodiments enable the synthesis of propylene and its polymer starting from CO2. The process should be employable on a large industrial scale. The yield should be as high as possible and the molecular weight should have a narrow distribution (i.e., the polydispersity should be low). The disclosed embodiments provide a process for producing propylene (III) or polypropylene from CO2 comprising: a) electrocatalytic reduction of the CO2 to generate methylglyoxal (I),b) reduction of the methylglyoxal (I) from operation a) with a reducing agent to generate the corresponding 1,2-diol (II) andc) elimination of the hydroxide groups of the 1,2-diol (II) from operation b) to generate propylene (III) according to the following reaction equation: The compound of formula (I) is methylglyoxal, the 1,2-diol of formula (II) is 1,2-propanediol and the compound of formula (III) is propylene (propene). The disclosed embodiments also provide for the respective use of the reagents recited in exemplary embodiments (such as catalysts, reducing agents etc.) for producing propylene or polypropylene from CO2, especially in the process disclosed. Finally, the disclosed embodiments also provide for the use of CO2 for production of propylene and/or polypropylene, especially the use in the process disclosed. The disclosed embodiments make it possible for the first time to produce propylene or its polymer polypropylene from CO2. The electrocatalytic reduction in operation a) may employ known catalysts. The reduction of the formed methylglyoxal in operation b) should employ a reducing agent (or else two or more different reducing agents) capable of reducing both C═O groups on the methylglyoxal to the hydroxy groups. The hydroxide groups o