Process for converting gaseous alkanes to olefins and liquid hydrocarbons

Abstract

A process for converting gaseous alkanes to olefins and liquid hydrocarbons wherein a gaseous feed containing alkanes is reacted with a dry bromine vapor to form alkyl bromides and hydrobromic acid vapor. The mixture of alkyl bromides and hydrobromic acid are then reacted over a synthetic crystalline alumino-silicate catalyst, such as an X or Y type zeolite, at a temperature of from about 250° C. to about 500° C. so as to form olefins, higher molecular weight hydrocarbons and hydrobromic acid vapor. Various methods are disclosed to remove the hydrobromic acid vapor from the higher molecular weight hydrocarbons and to generate bromine from the hydrobromic acid for use in the process.

1 . A process for converting gaseous alkanes to olefins and liquid hydrocarbons comprising: 
 reacting a gaseous feed having lower molecular weight alkanes with bromine vapor to form alkyl bromides and hydrobromic acid; and    reacting said alkyl bromides and hydrobromic acid in the presence of a synthetic crystalline alumino-silicate catalyst and at a temperature sufficient to form olefins and hydrobromic acid vapor.    
     
     
         2 . The process of  claim 1  wherein said bromine vapor is substantially dry, thereby avoiding the formation of significant carbon dioxide along with said alkyl bromides.  
     
     
         3 . The process of  claim 1  wherein said gaseous feed is natural gas.  
     
     
         4 . The process of  claim 3  wherein said natural gas is treated to remove substantially all of the carbon dioxide and sulfur compounds therefrom prior to reacting with said bromine vapor.  
     
     
         5 . The process of  claim 1  wherein said temperature is from about 250° C. to about 500° C.  
     
     
         6 . The process of  claim 5  wherein said temperature is from about 300° C. to about 450° C.  
     
     
         7 . The process of  claim 1  wherein said crystalline alumino-silicate catalyst is a zeolite catalyst.  
     
     
         8 . The process of  claim 7  wherein said zeolite catalyst is an X or Y type zeolite catalyst.  
     
     
         9 . The process of  claim 8  wherein said zeolite catalyst is a 10 X zeolite catalyst.  
     
     
         10 . The process of  claim 1  further comprising: 
 removing said hydrobromic acid vapor from said olefins by neutralization reaction with an aqueous solution containing reaction products obtained by oxidizing an aqueous solution containing a metal bromide salt, the metal of said metal bromide salt being selected from Cu, Zn, Fe, Co, Ni, Mn, Ca or Mg bromide.    
     
     
         11 . The process of  claim 1  wherein said bromine vapor is produced by oxidizing an aqueous metal bromide salt solution, the metal of said metal bromide salt being selected from Cu, Zn, Fe, Co, Ni, Mn, Ca, or Mg.  
     
     
         12 . A process for converting gaseous lower molecular weight alkanes to olefins comprising: 
 reacting a gaseous feed containing lower molecular weight alkanes with bromine vapor to form alkyl bromides and hydrobromic acid;    reacting said alkyl bromides and hydrobromic acid in the presence of a synthetic crystalline alumino-silicate catalyst to form olefins and hydrobromic acid; and    converting said hydrobromic acid to bromine.    
     
     
         13 . The process of  claim 12  further comprising: 
 dehydrating said olefins.    
     
     
         14 . The process of  claim 12  further comprising: 
 recycling said bromine that is converted from said hydrobromic acid to said step of reacting with said gaseous feed, said bromine being recycled as a vapor.    
     
     
         15 . A process for converting gaseous alkanes to olefins comprising: 
 reacting a gaseous feed having lower molecular weight alkanes with bromine vapor to form alkyl bromides and hydrobromic acid;    reacting said alkyl bromides and hydrobromic acid in the presence of a synthetic crystalline alumino-silicate catalyst and at a temperature sufficient to form olefins and hydrobromic acid vapor; and    removing said hydrobromic acid vapor from said olefins by reacting said hydrobromic acid vapor with a metal oxide to form a metal bromide and steam.    
     
     
         16 . The process of  claim 15  wherein said the metal of said metal oxide is magnesium, calcium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc or tin.  
     
     
         17 . The process of  claim 15  wherein said metal oxide is supported on a solid carrier.  
     
     
         18 . The process of  claim 15  wherein said metal oxide is contained in a bed in a reactor.  
     
     
         19 . The process of  claim 15  further comprising: 
 reacting said metal bromide with an oxygen containing gas to obtain a metal oxide and said bromine vapor.    
     
     
         20 . The process of  claim 19  wherein said bromine vapor is used in the step of reacting said gaseous feed having lower molecular weight alkanes.