Process for pre-reforming hydrocarbon fuels
View Patent ↗In a process for forming a methane-enriched fuel, a hydrocarbon feedstock that includes hydrocarbons having molecular weights greater than that of methane (CH 4 ) is mixed with an oxidizable gaseous reactant that includes water (H 2 O) and is free of molecular oxygen (O 2 ). The mixture, which has a H 2 O/total hydrocarbon (H 2 O/C) ratio of less than about 1, is heated to an elevated temperature in the presence of a catalyst to form a methane-enriched pre-reformate product. At least a portion of the feedstock hydrocarbons having molecular weights greater than that of methane is converted to methane (CH 4 ) in the process.
1. A process for forming a methane-enriched fuel from a hydrocarbon feedstock, said process comprising:
forming a mixture of a hydrocarbon feedstock that includes hydrocarbons having molecular weights greater than that of methane (CH 4 ) and an oxidizable gaseous reactant that comprises water (H 2 O) and is free of molecular oxygen (O 2 ), said mixture having a H 2 O/total hydrocarbon (H 2 O/C) ratio of less than 1; and
heating said mixture to an elevated temperature in the presence of a catalyst to form a methane-enriched pre-reformate product;
whereby at least a portion of said hydrocarbons having molecular weights greater than that of methane is converted to methane (CH 4 ).
2. The process of claim 1 wherein said mixture has a H 2 O/total hydrocarbon (H 2 O/C) ratio of less than 0.5.
3. The process of claim 2 wherein said mixture has a H 2 O/total hydrocarbon (H 2 O/C) ratio of less than 0.25.
4. The process of claim 1 wherein said hydrocarbon feedstock is selected from the group consisting of natural gas, liquefied petroleum gas (LPG), propanes, butanes, naphthas, gasolines, kerosenes, gas-oils, diesel fuels, coal liquids, tar sands, tar sand liquids, and mixtures thereof.
5. The process of claim 1 wherein said gaseous reactant comprises hydrogen (H 2 ) and carbon monoxide (CO).
6. The process of claim 1 wherein said gaseous reactant comprises anode tail gas from a fuel cell.
7. The process of claim 1 wherein said gaseous reactant comprises at least about 10% reducible gases.
8. The process of claim 7 wherein said gaseous reactant comprises at least about 20% reducible gases.
9. The process of claim 1 wherein said catalyst comprises rhodium (Rh).
10. The process of claim 1 wherein said catalyst comprises nickel (Ni).
11. The process of claim 1 wherein said elevated temperature is about 500° C. to 700° C.
12. The process of claim 1 wherein said methane-enriched pre-reformate product has a hydrogen/carbon (H/C) ratio of at least 3.85.
13. The process of claim 12 wherein said methane-enriched pre-reformate product has a hydrogen/carbon (H/C) ratio of at least 3.90.
14. The process of claim 1 wherein no more than about 40% of carbon present in said hydrocarbon feedstock is converted into non-methane carbon species.
15. The process of claim 14 wherein no more than about 30% of carbon present in said hydrocarbon feedstock is converted into non-methane carbon species.