Liquefied Petroleum Gas For LP Gas Fuel Cell, Method of Desulfurizing the Same and Fuel System

Abstract

The invention provides a liquefied petroleum gas fuel for LP gas fuel cells for being fed to a fuel cell system through spontaneous vaporization, which fuel has a C2 hydrocarbon compound content of 3 vol. % or less, a C4 hydrocarbon compound content of 3 vol. % or less, a total sulfur content of 10 ppm by mass or less, a carbonyl sulfide content in terms of sulfur content of 2 ppm by mass or less, a methyl mercaptan content in terms of sulfur content of 3 ppm by mass or less, a content of sulfur compounds having a boiling point equal to or higher than that of dimethyl disulfide in terms of sulfur content of 2 ppm by mass or less, a methanol content of 50 ppm by mass or less, and a water content of 50 ppm by mass or less, the balance being a C3 hydrocarbon compounds. The liquefied petroleum gas fuel for LP gas fuel cells ensures effective performance of a desulfurizing agent even when used in a minimum amount, thereby enhancing desulfurization performance, prevents damaging of a reforming catalyst employed in a reformer for producing hydrogen provided on the downstream side of a desulfurizer, and realizes reliable operation of the reformer and consistent generation of electric power. The invention also provides a method for desulfurizing the liquefied petroleum gas fuel, and a fuel cell system employing a hydrogen-containing gas produced through reforming of the liquefied petroleum gas fuel which has been desulfurized through the desulfurization method.

1 . A liquefied petroleum gas fuel for LP gas fuel cells for being fed to a fuel cell system through spontaneous vaporization, which fuel has a C2 hydrocarbon compound content of 3 vol. % or less, a C4 hydrocarbon compound content of 3 vol. % or less, a total sulfur content of 10 ppm by mass or less, a carbonyl sulfide content in terms of sulfur content of 2 ppm by mass or less, a methyl mercaptan content in terms of sulfur content of 3 ppm by mass or less, a content of sulfur compounds having a boiling point equal to or higher than that of dimethyl disulfide in terms of sulfur content of 2 ppm by mass or less, a methanol content of 50 ppm by mass or less, and a water content of 50 ppm by mass or less, the balance being a C3 hydrocarbon compounds. 
   
   
       2 . The liquefied petroleum gas fuel for LP gas fuel cells as described in  claim 1 , wherein the C2 hydrocarbon compound content is 1 vol. % or less, and the C4 hydrocarbon compound content is 2 vol. % or less, the balance being C3 hydrocarbon compounds. 
   
   
       3 . The liquefied petroleum gas fuel for LP gas fuel cells as described in  claim 1 , which has a C3 olefin content of 0.1 vol. % or less, and a C4 olefin and/or diolefin content of 0.1 vol. % or less. 
   
   
       4 . The liquefied petroleum gas fuel for LP gas fuel cells as described in  claim 3 , which has a C4 diolefin content of 0.03 vol. % or less. 
   
   
       5 . A desulfurization method comprising spontaneously vaporizing a liquefied petroleum gas fuel for LP gas fuel cells as recited in  claim 1  and desulfurizing by use of a desulfurizing agent. 
   
   
       6 . The desulfurization method as described in  claim 5 , wherein the desulfurizing agent comprises a zeolite-containing desulfurizing agent and/or at least one species selected from among a metallic element, a metal oxide, and a metallic component-on-oxide. 
   
   
       7 . The desulfurization method as described in  claim 6 , wherein the zeolite-containing desulfurizing agent comprises zeolite and at least one metallic component selected from among an Ag component, a Cu component, an Ni component, a Zn component, an Mn component, an Fe component, a Co component, an alkali metal component, an alkaline earth metal component, and a rare earth metal component. 
   
   
       8 . The desulfurization method as described in  claim 6 , wherein the zeolite has a β (BEA) structure and/or a faujasite (FAU) structure. 
   
   
       9 . The desulfurization method as described in  claim 6 , wherein the desulfurizing agent comprising at least one species selected from among a metallic element, a metal oxide, and a metallic component-on-oxide, contains at least one metallic component selected from among an Ag component, a Cu component, an Ni component, a Zn component, an Mn component, an Fe component, a Co component, an Si component, and an Al component, an alkali metal component, an alkaline earth metal component, and a rare earth metal component. 
   
   
       10 . An LP gas fuel cell system characterized by employing a hydrogen-containing gas produced from a reforming product of a liquefied petroleum gas fuel which has been desulfurized through a desulfurization method as recited in  claim 5 . 
   
   
       11 . The LP gas fuel cell system as described in  claim 10 , wherein reforming is partial-oxidation reforming, auto-thermal reforming, steam reforming, or carbon dioxide reforming.