Methods for photocatalytic water splitting of produced waters

Patent metadata

Field	Value
Publication number	US-12589993-B2
Application number	US-202418664126-A
Country	US
Kind code	B2
Filing date	May 14, 2024
Priority date	May 14, 2024
Publication date	Mar 31, 2026
Grant date	Mar 31, 2026

Abstract

Methods for photocatalytic water splitting of produced waters may comprise introducing a photocatalyst comprising a semiconductor to a produced water comprising ions of sodium, chloride, calcium, magnesium, potassium, sulfate, barium, iron, lithium, strontium, or any combination thereof; in the presence of sunlight, allowing the photocatalyst to facilitate a reduction-oxidation reaction of a plurality of water molecules from the produced water; and obtaining hydrogen and oxygen.

First claim

The invention claimed is:

1 . A method comprising:
introducing a photocatalyst comprising a semiconductor comprising (i) titanium dioxide and/or a perovskite and (ii) indium gallium nitride, and a cocatalyst comprising a noble metal or a transition metal oxide, wherein the cocatalyst is on a surface of the photocatalyst, to a produced water comprising ions of sodium, chloride, calcium, magnesium, potassium, sulfate, barium, iron, lithium, strontium, or any combination thereof; in the presence of sunlight, allowing the photocatalyst to facilitate a reduction-oxidation reaction of a plurality of water molecules from the produced water; and obtaining hydrogen and oxygen.

2 . The method of claim 1 , further comprising:
adsorbing the plurality of water molecules from the produced water onto a surface of the photocatalyst; absorbing a photon energy from the sunlight by the photocatalyst greater than a band-gap energy of the semiconductor; and generating a plurality of photoexcited electron hole pairs within the photocatalyst that migrate to the surface of the photocatalyst thereby facilitating the reduction-oxidation reaction.

3 . The method of claim 1 , wherein the produced water has a total dissolved solids concentration of about 3 ppm to about 60,000 ppm.

4 . The method of claim 1 , wherein the produced water has a concentration of sodium ions of about 10 mg/L to about 50 mg/L.

5 . The method of claim 1 , wherein the produced water has a concentration of chloride ions of about 1 mg/L to about 50 mg/L.

6 . The method of claim 1 , wherein the produced water has a concentration of calcium ions of about 0.001 mg/L to about 10 mg/L.

7 . The method of claim 1 , wherein the produced water has a concentration of magnesium ions of about 0.001 mg/L to about 10 mg/L.

8 . The method of claim 1 , wherein the produced water has a concentration of potassium ions of about 1 mg/L to about 50 mg/L.

9 . The method of claim 1 , wherein the produced water has a concentration of sulfate ions of about 1 mg/L to about 50 mg/L.

10 . The method of claim 1 , wherein the produced water has a concentration of barium ions of about 0.001 mg/L to about 10 mg/L.

11 . The method of claim 1 , wherein the produced water has a concentration of iron ions of about 0.001 mg/L to about 10 mg/L.

12 . The method of claim 1 , wherein the produced water has a concentration of lithium ions of about 1 mg/L to about 50 mg/L.

13 . The method of claim 1 , wherein the produced water has a concentration of strontium ions of about 0.001 mg/L to about 10 mg/L.

14 . The method of claim 1 , wherein the produced water has three or more of the following characteristics:
a total dissolved solids concentration of about 30,000 ppm to about 60,000 ppm; a concentration of sodium ions of about 25 mg/L to about 50 mg/L; a concentration of chloride ions of about 25 mg/L to about 50 mg/L; a concentration of calcium ions of about 2 mg/L to about 10 mg/L; a concentration of magnesium ions of about 2 mg/L to about 10 mg/L; a concentration of potassium ions of about 25 mg/L to about 50 mg/L; a concentration of sulfate ions of about 10 mg/L to about 50 mg/L; a concentration of barium ions of about 2 mg/L to about 10 mg/L; and, a concentration of iron ions of about 2 mg/L to about 10 mg/L.

15 . The method of claim 1 , wherein the produced water has the following characteristics:
a total dissolved solids concentration of about 30,000 ppm to about 60,000 ppm; a concentration of sodium ions of about 25 mg/L to about 50 mg/L; a concentration of chloride ions of about 25 mg/L to about 50 mg/L; a concentration of calcium ions of about 2 mg/L to about 10 mg/L; a concentration of barium ions of about 2 mg/L to about 10 mg/L; and, a concentration of iron ions of about 2 mg/L to about 10 mg/L.

16 . A method comprising:
introducing a photocatalyst comprising a semiconductor and a cocatalyst comprising a noble metal or a transition metal oxide, wherein the cocatalyst is on a surface of the photocatalyst, to a produced water having a total dissolved solids concentration of about 3 ppm to about 60,000 ppm and comprising ions of sodium, chloride, calcium, magnesium, potassium, sulfate, barium, iron, lithium, strontium, or any combination thereof; wherein the semiconductor comprises (i) titanium dioxide and/or a perovskite, and (ii) indium gallium nitride; and the cocatalyst comprises Pt, Rh, NiO x , or RuO 2 ; adsorbing a plurality of water molecules from the produced water onto a surface of the photocatalyst; absorbing a photon energy from the sunlight by the photocatalyst greater than a band-gap energy of the semiconductor; generating a plurality of photoexcited electron hole pairs within the photocatalyst that migrate to the surface of the photocatalyst thereby facilitating a reduction-oxidation reaction of the plurality of water molecules; and obtaining hydrogen and oxygen.

17 . The method of claim 1 , wherein the cocatalyst comprises Pt, Rh, NiO x , or RuO 2 .

Assignees

• Saudi Arabian Oil Co

Inventors

• Alqahtani Hassan Sakar
• Alghunaimi Fahd Ibrahim
• Hazazi Khalid Yahya
• Al-Saleh Salah Hamad

Classifications

• C01B13/0207

  Water · CPC title

• C01B2203/0277

  containing a catalytic decomposition step · CPC title

• C01B2203/1094

  Promotors or activators · CPC title

• Y02E60/36

  Hydrogen production from non-carbon containing sources, e.g. by water electrolysis · CPC title

• C01B3/042 Primary

  Decomposition of water (by electrolysis of water C25B1/04) · CPC title