Water photolysis system and process

Abstract

The present invention provides a water photolysis system comprising: a casing 1 into which incident sunlight L can enter from the outside and a photolytic layer 5 which is disposed inside the casing 1; wherein the photolytic layer 5 has a light-transmissive porous material 51 and photocatalyst particles 52 supported thereon; a water layer 4 containing water in its liquid state is disposed below the photolytic layer 5 with a first space 6 disposed between the water layer and the photolytic layer; a sealed second space 7 is formed above the photolytic layer 5 in the casing 1; vapor generated from the water layer 4 is introduced into the photolytic layer 5 via the first space 6; and the vapor is decomposed into hydrogen and oxygen by the photocatalyst particles 52, which are excited by the sunlight L.

1 . A water photolysis system comprising: 
 a casing into which incident light can enter from the outside and a photolytic layer which is disposed inside the casing;    wherein the photolytic layer has a light-transmissive porous material and a photocatalyst supported on the porous material;    a water layer containing water in its liquid state is placed below the photolytic layer via a first space;    a sealed second space is formed above the photolytic layer in the casing; and    vapor generated from the water layer is introduced into the photolytic layer via the first space and the vapor is decomposed into hydrogen and oxygen by the photocatalyst, which is excited by the incident light.    
     
     
         2 . A water photolysis system according to  claim 1 , wherein the water layer is disposed inside the casing.  
     
     
         3 . A water photolysis system according to  claim 1 , wherein the casing is provided with a light-heat conversion layer which contacts the water layer and is capable of absorbing the incident light.  
     
     
         4 . A water photolysis system according to  claim 3 , wherein the light-heat conversion layer is composed of a thin metal film placed on the bottom surface of the water layer.  
     
     
         5 . A water photolysis system according to  claim 3 , wherein the light-heat conversion layer is composed of a black board placed on the bottom surface of the water layer.  
     
     
         6 . A water photolysis system according to  claim 1 , wherein the bottom part of the casing is provided with an opening, and the water layer is introduced into the casing via the opening from the outside.  
     
     
         7 . A water photolysis system according to  claim 6 , wherein the casing is placed in a floating condition on the water layer.  
     
     
         8 . A water photolysis system according to  claim 7 , wherein the water layer is composed of water in an indoor or outdoor swimming pool, sea, pond or lake.  
     
     
         9 . A water photolysis system according to  claim 1 , wherein an inlet port for introducing water in its liquid state into the water layer inside the casing is formed in a wall of the casing.  
     
     
         10 . A water photolysis system according to  claim 9 , wherein the bottom part of the casing is provided with an opening.  
     
     
         11 . A water photolysis system according to  claim 1 , wherein the casing is placed with the bottom part thereof contacting the bottom of the water layer.  
     
     
         12 . A water photolysis system according to  claim 1 , wherein the casing is composed of colorless and transparent materials.  
     
     
         13 . A water photolysis system according to  claim 1 , wherein the incident light is sunlight.  
     
     
         14 . A water photolysis system according to  claim 1 , wherein the porous material has a  3 -dimensional reticulated skelton and supports photocatalyst particles.  
     
     
         15 . A water photolysis system according to  claim 14 , wherein the porosity of the porous material is in a range of 50% or more to 98% or less.  
     
     
         16 . A water photolysis system according to  claim 14 , wherein the porous material surface is water repellent.  
     
     
         17 . A water photolysis system according to  claim 1 , wherein a outlet port for evacuating gas in the second space to the outside is formed in an inner wall of the casing.  
     
     
         18 . A water photolysis system according, to  claim 17 , wherein the second space has a reduced atmosphere.  
     
     
         19 . A water photolysis system according to  claim 17 , wherein an inlet port for introducing inert gas into the second space is formed in a wall of the casing.  
     
     
         20 . A water photolysis system according to  claim 1;   wherein the second space is separated into two gas accumulation parts disposed vertically on either side of a hydrogen separation membrane; and    a outlet port for evacuating gas from the gas accumulation part disposed above the hydrogen separation membrane to the outside is formed in a wall of the casing.    
     
     
         21 . A water photolysis system according to  claim 20 , wherein an inlet port for introducing an inert gas into the gas accumulation part disposed below the hydrogen separation membrane is formed in a wall of the casing.  
     
     
         22 . A water photolysis system according to  claim 20 , wherein the pressure of the gas accumulation part disposed above the hydrogen separation membrane is maintained to be lower than that of the other gas accumulation part, and the pressure difference between both gas accumulation parts is in a range of 1.3×10 4  Pa or more to 1×10 6  Pa or less.  
     
     
         23 . A process for photolyzing water comprising the steps of: 
 placing a photolytic layer provided with a light-transmissive porous material and a photocatalyst supported on the porous material on a water layer containing water in its liquid state with a first space therebetween;    irradiating light onto the photolytic layer; and    decomposing vapor generated from the water layer into hydrogen and oxygen by the photocatalyst, which is excited by the incident light, when the vapor is introduced to the photolytic layer via the first space.    
     
     
         24 . A process for photolyzing water according to  claim 23 , wherein 
 the photolytic layer is disposed inside a casing into which an incident light can enter; and    a sealed second space is formed above the photolytic layer in the casing and the resulting hydrogen and oxygen are collected in the second space.    
     
     
         25 . A process for photolyzing water according to  claim 23 , wherein a light-heat conversion layer which contacts the water layer is disposed below the photolytic layer.  
     
     
         26 . A process for photolyzing water according to  claim 23 , wherein the incident light is sunlight.  
     
     
         27 . A process for photolyzing water according to  claim 23 , wherein the porous material has a  3 -dimensional reticulated skelton and supports photocatalyst particles.  
     
     
         28 . A process for photolyzing water according to  claim 27 , wherein the porosity of the porous material is in a range of 50% or more to 98% or less.  
     
     
         29 . A process for photolyzing water according to  claim 27 , wherein the porous material surface is water-repellent.  
     
     
         30 . A process for photolyzing water according to  claim 23 , wherein the water layer is composed of water in an indoor or outdoor swimming pool, sea, pond or lake.