Low energy surfaces for reduced corrosion and fouling

Abstract

This invention relates to metal surfaces and a method for reducing fouling of metal surfaces. More particularly, metal surfaces such as piping and heat exchangers that transport or contain corrosive and contaminated materials can be protected by formation of organometallic coatings which are in the range of monolayers in thickness.

1 . A process for mitigating fouling of metal surfaces which comprises: contacting the metal surface with an organometallic compound capable of bonding to the metallic surface and forming a layer of organometallic molecules which is 1 to 10 molecular layers thick, which layer will not undergo substantial decomposition at temperatures up to 450° C. and which layer has a surface energy lower than 50 millijoule/m 2 .  
   
   
       2 . A process for mitigating fouling in refinery and chemical plant equipment having metal surfaces containing corrosion layers which comprises: contacting a metal surface containing a corrosion layer with at least one of high pressure water or steam to produce a water or steam cleaned metal surface; heating the water or steam cleaned metal surface in an oxygen-containing atmosphere at temperatures of from 100 to 500° C. for a time sufficient to further clean said metal surface of carbonaceous residues, contacting the further cleaned metal surface with an organometallic compound capable of bonding to the metallic surface and forming a layer of organometallic molecules which is 1 to 10 molecular layers thick, which layer will not undergo substantial decomposition at temperatures up to 450 ° C., which layer forms a surface having a water contact angle between 95 to 160 degrees, and which layer is deposited on greater than 25% up to 100% of the metal surface.  
   
   
       3 . The process of claims  1  or 2 wherein the metal in the organometallic compound is from Group 4-15.  
   
   
       4 . The process of claims  1  or  2  wherein the layer of organometallic molecules is deposited on 80 to 100% of the metal surface.  
   
   
       5 . The process of  claim 1  wherein the metal surface is heated in an oxygen-containing atmosphere prior to contacting with organometallic compound.  
   
   
       6 . The process of claims  1  or  2  wherein the metal surface is carbon steel or stainless steel.  
   
   
       7 . The process of  claim 3  wherein the metal in the organometallic is from Group 14.  
   
   
       8 . The process of  claim 7  wherein the metal in the organometallic compound is silicon.  
   
   
       9 . The process of claims  1  or  2  wherein the organo moiety in the organometallic compound is a hydrocarbyl group from 1 to 30 carbon atoms.  
   
   
       10 . The process of  claim 9  wherein the hydrocarbyl group is aliphatic or aromatic.  
   
   
       11 . The process of  claim 10  wherein the hydrocarbyl group is substituted with at least one functional group.  
   
   
       12 . The process of claims  1  or  2  wherein the organometallic compound is an alkoxy silane, silane, silazone or phenyl siloxane.  
   
   
       13 . The process of  claim 12  wherein the organometallic compound is hexamethyldisiloxane.  
   
   
       14 . The process of  claim 1  wherein the surface energy is between 18 and 50 mJ/m 2 .  
   
   
       15 . The process of claims  1  or  2  wherein the organometallic compound is contacted with metal surface in the liquid phase, gaseous phase or mixed liquid-gaseous phase.  
   
   
       16 . The process of  claim 15  wherein the organometallic compound is contacted with metal surface in the presence of a carrier fluid.  
   
   
       17 . The process of claims  1  or  2  wherein the layer of organometallic molecules is from 1 to 3 molecular layers thick.  
   
   
       18 . The process of claims  1  or  2  wherein the temperature is less than 400° C.  
   
   
       19 . The process of  claim 5  wherein the metal surface is heated at temperatures of from 100 to 500° C.  
   
   
       20 . A metal surface capable of resisting fouling when exposed to corrosive or coke forming at atmospheric or greater pressures which comprises a metal surface and a layer of organometallic molecules deposited on said metal surface, said layer of organometallic molecules being 1 to 10 molecular layers thick, which layer will not undergo substantial decomposition at temperatures up to 450 ° C., which layer has a surface energy lower than 50 millijoule/m 2 .  
   
   
       21 . The metal surface of  claim 20  wherein the layer of organometallic molecules is deposited on 80 to 100% of the metal surface.