Methods for fuel conversion
In one embodiment described herein, fuel may be converted into syngas by a method comprising feeding the fuel and composite metal oxides into a reduction reactor in a co-current flow pattern relative to one another, reducing the composite metal oxides with the fuel to form syngas and reduced composite metal oxides, transporting the reduced composite metal oxides to an oxidation reactor, regenerating the composite metal oxides by oxidizing the reduced composite metal oxides with an oxidizing reactant in the oxidation reactor, and recycling the regenerated composite metal oxides to the reduction reactor for subsequent reduction reactions to produce syngas. The composite metal oxides may be solid particles comprising a primary metal oxide and a secondary metal oxide.
1. A method for converting gaseous fuel into syngas, the method comprising:
feeding the gaseous fuel and composite metal oxides into a reduction reactor having a top and a bottom, wherein the gaseous fuel and the composite metal oxides are fed into the top of the reduction reactor, whereupon the composite metal oxides form a packed bed and the composite metal oxides and the gaseous fuel flow downward through the reactor in a co-current flow pattern relative to one another;
reducing the composite metal oxides with the gaseous fuel in the reduction reactor to form syngas and reduced composite metal oxides wherein the syngas comprises hydrogen and carbon monoxide;
removing the syngas and the reduced composite metal oxides from the bottom of the reduction reactor;
transporting the reduced composite metal oxides to an oxidation reactor;
regenerating the composite metal oxides by oxidizing the reduced composite metal oxides with an oxidizing reactant in the oxidation reactor; and
recycling the regenerated composite metal oxides to the reduction reactor for subsequent reduction reactions to produce syngas in the reduction reactor;
wherein the composite metal oxides comprise iron, titanium and oxygen and the reduced metal oxides comprise FeO.TiO 2 , or wherein the composite metal oxides comprise iron aluminum and oxygen and the reduced metal oxides comprise FeO.Al 2 O 3 .
2. The method of claim 1 , wherein the fuel is natural gas.
3. The method of claim 1 , wherein the oxidizing reactant comprises air, oxygen, steam, carbon dioxide, or any combination thereof.
4. The method of claim 1 , wherein a ratio of hydrogen to carbon monoxide can be controlled.
5. The method of claim 1 , wherein the syngas comprises a stoichiometric ratio of carbon monoxide to hydrogen of about 1:2 and the gaseous fuel is natural gas.
6. The method of claim 1 , wherein the gaseous fuel is co-injected with a carbon-rich or hydrogen-rich reactant to change the carbon monoxide to hydrogen ratio of the syngas.
7. The method of claim 1 , wherein oxygen or oxygen releasing material is introduced in the reduction reaction to increase reaction kinetics for syngas production.
8. The method of claim 1 , wherein the reducing of the composite metal oxides occurs at a temperature in the range of between about 500° C. and about 1200° C.
9. The method of claim 1 , wherein the syngas comprises at least about 85 mol % carbon monoxide and hydrogen.
10. The method of claim 1 , wherein the syngas comprises less than about 10 mol % of carbon dioxide and less than about 10 mol % steam.
11. The method of claim 1 , wherein the composite metal oxides further comprises a dopant/promoter comprising Ca, Ce, Pt, Ru, Rh, La, Fe, Cu, oxides thereof, or any combination thereof.