Conversion of lignin into a water-soluble polyacid using a MOF catalyst
A process for valorization of lignin includes the steps of mixing lignin; a MOF catalyst metalated with a metal atom selected from the group consisting of Fe, Mn, Co, Cu, or Ni, and combinations thereof; an oxidizing agent; and an aqueous solvent. The product of this process, a charged polyacid-containing species derived from lignin, may be included in a dispersion with a dispersible particulate material, and an aqueous dispersing medium.
1. A process for valorization of lignin comprising:
mixing
lignin,
a MOF catalyst metalated with a metal atom selected from the group consisting of Fe, Mn, Co, Cu, or Ni, and combinations thereof;
an oxidizing agent; and
an aqueous solvent;
wherein the pH of the mixture is 2 to 10; and
recovering a product comprising a charged polyacid, wherein the charged polyacid when mixed with an alpha-aluminum oxide powder and water results in a zeta potential of the resulting dispersion of −30 to −80 mV at pH values above 6.
2. The process of claim 1 , wherein the MOF catalyst is a recovered MOF catalyst.
3. The process of claim 1 , wherein the metal atom is Fe.
4. The process of claim 1 , wherein the MOF catalyst comprises a node, the node including a zirconium atom; and the MOF catalyst comprises a linker including a heteroaromatic group, the linker being coupled to the node.
5. The process of claim 1 , wherein the MOF catalyst comprises a bipyridine-containing linker group.
6. The process of claim 1 , wherein the metal atom in the MOF catalyst reacts with the oxidizing agent to make a hydroxyl radical.
7. The process of claim 6 , wherein the hydroxyl radical reacts with an aromatic ring on the lignin causing the aromatic ring to open.
8. The process of claim 1 , wherein the oxidizing agent is a peroxide containing species.
9. The process of claim 1 , wherein a weight-average molecular weight of the lignin ranges from 1,000 to 4,000 g/mol.
10. The process of claim 1 , wherein an aromatic ring on the lignin is opened by one or more reactants.
11. The process of claim 1 , wherein the pH of the mixture is 2 to 6.
12. A process for valorization of lignin comprising:
mixing
lignin,
a MOF catalyst metalated with a metal atom selected from the group consisting of Fe, Mn, Co, Cu, or Ni, and combinations thereof;
an oxidizing agent; and
an aqueous solvent;
wherein the pH of the mixture is 2 to 10;
further comprising recovering the MOF catalyst.
13. The process of claim 12 , wherein the MOF catalyst comprises a node, the node including a zirconium atom; and the MOF catalyst comprises a linker including a heteroaromatic group, the linker being coupled to the node.
14. The process of claim 12 , wherein the metal atom is Fe.
15. A reaction mixture comprising:
lignin;
a MOF catalyst metalated with a metal atom selected from the group consisting of Fe, Mn, Co, Cu, or Ni, and combinations thereof;
an oxidizing agent; and
an aqueous solvent;
wherein the oxidizing agent is a peroxide-containing species;
wherein the pH of the mixture is 2 to 10;
wherein the MOF catalyst comprises a node, the node including a zirconium atom; and the MOF catalyst comprises a linker including a heteroaromatic group, the linker being coupled to the node.
16. The reaction mixture of claim 15 , wherein the lignin has an Mw/Mn ranging from 2 to 5.
17. The reaction mixture of claim 15 , wherein the MOF catalyst is a recovered MOF catalyst.
18. The reaction mixture of claim 15 , wherein the metal atom is Fe.
19. The reaction mixture of claim 15 , wherein the MOF catalyst comprises a second linker including an aromatic group, the linkers being coupled to the nodes.