CERIA SUPPORTED PALLADIUM/CALCIUM CATALYST FOR HYDROGENATING CO2 TO DIMETHYL ETHER

• US 20200129960A1
• Filed: 10/31/2018
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: King Abdul AZIZ University
• Original Assignee: King Abdul AZIZ University
• Inventors: ZAMAN, Sharif Fakhruz, MALIK, Ali Shan, ALZAHRANI, Abdulrahim Ahmed, DAOUS, Muhammad A., PETROV, Lachezar A.
• Granted Patent: US 10,710,056 B2
• Time in Patent Office: Days
• CPC Class Codes: B01J 23/10 of rare earths
• CPC Class Codes: B01J 23/44 Palladium
• CPC Class Codes: B01J 23/58 with alkali- or alkaline earth metals
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 35/23 in a colloidal state
• CPC Class Codes: B01J 35/50 characterised by their shape or configuration
• CPC Class Codes: B01J 35/613 10-100 m2/g
• CPC Class Codes: B01J 37/0236 Drying, e.g. preparing a suspension, adding a soluble salt and drying
• CPC Class Codes: B01J 37/036 to form a gel or a cogel
• CPC Class Codes: B01J 37/04 Mixing B01J37/0009, B01J37/0018 take precedence
• CPC Class Codes: B01J 37/08 Heat treatment B01J37/0009, B01J37/0018 take precedence
• CPC Class Codes: B01J 37/18 with gases containing free hydrogen
• CPC Class Codes: C07C 41/01 Preparation of ethers
• CPC Class Codes: C07C 43/043 Dimethyl ether

Abstract

Catalysts for hydrogenation of CO₂ to dimethyl ether. These catalysts comprise 0.1-10 wt % per total catalyst weight of a catalytic material containing Pd (e.g. metallic palladium), 0.05-5 wt % per total catalyst weight of a promoter containing Ca (e.g. metallic calcium), as well as 85-99 wt % of CeO₂ as a catalyst support. Methods of preparing and characterizing the catalysts as well as processes for catalyzing the hydrogenation of CO₂ to dimethyl ether and other byproducts such as methanol, carbon monoxide, and methane portrayed by reactant conversion., product selectivity, and catalyst stability are disclosed.

Claims

1. A CeO₂ supported palladium catalyst, comprising:

0.05-2 wt % of a promoter comprising Ca;

1-8 wt % of a catalytic material comprising Pd; and

90-98 wt % of CeO₂, each relative to a total weight of the CeO₂ supported palladium catalyst,

wherein;

the CeO₂ supported palladium catalyst has an atomic ratio of palladium to calcium ranging from 2;

1 to 6;

1; and

the promoter and the catalytic material are deposited on the CeO₂.

2. The CeO₂ supported palladium catalyst of claim 1, wherein the promoter and the catalytic material are in the form of particles.

3. The CeO₂ supported palladium catalyst of claim 1, which has a surface area of 50-100 m²/g.

5. The CeO₂ supported palladium catalyst of claim 1, which has an atomic ratio of cerium to palladium ranging from 7:

1 to 50;

1.

6. A method of preparing the CeO₂ supported palladium catalyst of claim 1, the method comprising:

heating an aqueous solution of a Ce(III) salt and citric acid to form a first mixture;

mixing the first mixture with an aqueous solution of a Pd(II) salt and an aqueous solution of a Ca(II) salt to form a second mixture;

heating the second mixture to form a gel;

drying the gel to form a dried powder;

calcining the dried powder in air to form a pre-catalyst; and

subjecting the pre-catalyst to H₂ gas thereby forming the CeO₂ supported palladium catalyst.

7. The method of claim 6, wherein a molar ratio of the citric acid to a total content of the Ce(III) salt and the Pd(II) salt ranges from 2:

1 to 10;

1.

8. The method of claim 6, wherein a molar ratio of the Pd(II) salt to the Ca(II) salt ranges from 1:

50 to 75;

1, and a molar ratio of the Ce(III) salt to the Pd(II) salt ranges from 5;

1 to 500;

1.

9. The method of claim 6, wherein the Ce(III) salt is cerium(III) nitrate.

10. The method of claim 6, wherein the Pd(II) salt is palladium(II) nitrate.

11. The method of claim 6, wherein the Ca(II) salt is calcium(II) nitrate.

12. A process of producing dimethyl ether from CO₂ and H₂, the process comprising:

contacting a stream comprising CO₂ and H₂ with the CeO₂ supported palladium catalyst of claim 1 in a reactor, thereby producing dimethyl ether and at least one side product selected from the group consisting of methanol, carbon monoxide, and methane,

wherein a molar ratio of the H₂ to the CO₂ ranges from 1;

1 to 6;

1.

13. The process of claim 12, wherein the stream has a gas hourly space velocity of 1,800-12,000 mL/g·

hr.

14. The process of claim 12, wherein the stream is contacted with the CeO₂ supported palladium catalyst at a temperature of 250-400°

C.

15. The process of claim 12, wherein the stream is contacted with the CeO₂ supported palladium catalyst at a pressure of 1-30 bar.

16. The process of claim 12, wherein the stream further comprises an inert carrier gas.

17. The process of claim 12, wherein 7-80 mol % of the CO₂ present in the stream is converted to dimethyl ether and the at least one side product.

18. The process of claim 12, wherein a selectivity for dimethyl ether converted from the CO₂ ranges from 18-80%.

19. The process of claim 12, wherein a selectivity for carbon monoxide converted from the CO₂ is less than 22%, a selectivity for methane converted from the CO₂ is less than 20%, and a selectivity for methanol converted from the CO₂ is less than 30%.

20. The process of claim 12, wherein a conversion of CO₂ and a selectivity for dimethyl ether are maintained over a reaction period of 90 or more hours.

21. A process of producing dimethyl ether from CO₂ and H₂, the process comprising:

contacting a stream comprising CO₂ and H₂ with the CeO₂ supported palladium catalyst of claim 1 in a reactor, thereby producing dimethyl ether and at least one side product selected from the group consisting of methanol, carbon monoxide, and methane,

wherein a molar ratio of the H₂ to the CO₂ ranges from 1;

1 to 6;

1.

22. The process of claim 21, wherein the stream is contacted with the CeO₂ supported palladium catalyst at a temperature of 250-400°

C., at a pressure of 1-30 bar, and at a gas hourly space velocity of 1,800-12,000 mL/g·

hr.

23. The process of claim 21, wherein a selectivity for dimethyl ether converted from the CO₂ ranges from 18-80%, a selectivity for carbon monoxide converted from the CO₂ is less than 22%, a selectivity for methane converted from the CO₂ is less than 20%, and a selectivity for methanol converted from the CO₂ is less than 30%.

4. (canceled)