Compositions for reducing atmosheric oxidising pollutants

Abstract

A composition for reducing atmospheric oxidizing pollutants comprising a reducing agent comprising: at least one transition element and/or one or more compounds including at least one transition element wherein the standard electrode potential of the redox reaction including the transition element and an ionic species of the transition element or between the ionic species of the transition element present in the or each compound and a further ionic species of the transition element is less than +1.0 volt; a precious metal-free trap material capable of trapping at least one atmospheric reducing pollutant, whereby the at least one atmospheric oxidizing pollutant is reduced by a combination of the trap material and at least one trapped atmospheric reducing pollutant, which at least one trapped atmospheric reducing pollutant is consequently oxidized; or a manganese-based catalyst, preferably MnO 2 or a derivative thereof including cryptomelane, and a water soluble binder.

1 . A heat exchanger comprising an atmosphere-contacting surface coated with a composition for reducing atmospheric oxidising pollutants, which composition comprises a reducing agent comprising a manganese-based catalyst and a water soluble binder.  
     
     
         2 . A heat exchanger according to  claim 1 , wherein the manganese-based catalyst is MnO 2  or a derivative thereof.  
     
     
         3 . A heat exchanger according to  claim 2 , wherein the MnO 2  derivative is cryptomelane.  
     
     
         4 . A heat exchanger according to  claim 1 , wherein the water-soluble binder is a cellulosic binder.  
     
     
         5 . A heat exchanger according to  claim 4 , wherein the cellulosic binder is selected from the group consisting of an ether ester and semi-synthetic cellulosic binder.  
     
     
         6 . A heat exchanger according to  claim 1 , wherein the water soluble binder is a vinyl or acrylic binder.  
     
     
         7 . A heat exchanger according to  claim 1 , wherein the manganese-based catalyst is supported on a high surface area oxide selected from the group consisting of alumina, ceria, silica, titania, zirconia and a mixed oxide of any two or more thereof.  
     
     
         8 . A heat exchanger according to  claim 1 , wherein the composition further comprises particles of a transition metal for improving the thermal conductivity of the composition.  
     
     
         9 . A heat exchanger according to  claim 1 , wherein the surface comprises aluminium or an aluminium alloy.  
     
     
         10 . A heat exchanger according to  claim 1 , wherein the heat exchanger is a radiator and/or a condenser.  
     
     
         11 . A method of making a heat exchanger comprising an atmosphere-contacting surface coated with a composition for reducing atmospheric oxidising pollutants, which composition comprises a reducing agent comprising a manganese-based catalyst and a water soluble binder, which method comprises the steps of coating the surface with the composition and heating the coated surface for a sufficient time to cure the composition, wherein the heating step consists of heating the coated surface to ≦90° C.  
     
     
         12 . A heat exchanger according to  claim 4 , wherein the cellulosic binder is hydroxypropyl- or methylcellulose.  
     
     
         13 . A heat exchanger according to  claim 1 , wherein the water soluble binder is polyvinyl alcohol or ammonium polymethacrylate.  
     
     
         14 . A heat exchanger according to  claim 8 , wherein the transition metal is silver or copper.  
     
     
         15 . A heat exchanger according to  claim 10 , wherein the radiator and/or a condenser is part of a motor vehicle.