Method of minimizing aldehyde based impurities in a process stream

Abstract

Oxidation of an alkane to an alkanone in a process stream forms aldehyde-based impurities. A method of minimizing the aldehyde-based impurities introduces an amine into the process stream to minimize the aldehyde-based impurities. The amine interacts with the alkanone and the aldehyde-based impurities thereby forming heavy products. The method separates the heavy products from the alkanones to reduce a level of the aldehyde-based impurities. The process stream preferably includes cyclohexyl ketone as the alkanone and n-hexanal as the aldehyde-based impurity. The method is typically involved in synthesis of a caprolactam.

1 . A method of minimizing aldehyde-based impurities in a process stream comprising an alkanone and the aldehyde-based impurities, said method comprising the steps of: 
 introducing an amine into the process stream to form a heavy product; and    separating the alkanone from the heavy product.    
   
   
       2 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the step of introducing the amine comprises the step of interacting the amine with the aldehyde-based impurities to form the heavy product.  
   
   
       3 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 2  wherein the step of interacting the amine further comprises the step of chemically reacting the alkanone with the aldehyde-based impurities to form an alkylenyl alkanone as the heavy product.  
   
   
       4 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the amine is selected from the group of ethylenediamine, diethylenetriamine, triethylenetetramine, and combinations thereof.  
   
   
       5 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the amine comprises diethylenetriamine.  
   
   
       6 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the amine comprises triethylenetetramine.  
   
   
       7 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 4  wherein the aldehyde-based impurities comprise n-hexanal.  
   
   
       8 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 7  wherein the alkanone comprises a cyclic alkanone.  
   
   
       9 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 8  wherein the cyclic alkanone comprises cyclohexyl ketone.  
   
   
       10 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 9  wherein the step of separating the alkanone from the heavy product comprises the step of distilling the heavy product and the alkanone.  
   
   
       11 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 10  wherein the step of distilling the heavy product and the alkanone comprises the step of distilling the heavy product and the alkanone at a temperature of from 155° C. to 165° C.  
   
   
       12 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the aldehyde-based impurities comprise n-hexanal.  
   
   
       13 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the alkanone comprises a cyclic alkanone.  
   
   
       14 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 13  wherein the cyclic alkanone comprises cyclohexyl ketone.  
   
   
       15 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the step of introducing the amine comprises the step of injecting the amine into the process stream.  
   
   
       16 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 15  wherein the step of injecting the amine into the process stream comprises the step of injecting the amine into a distillation tower.  
   
   
       17 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the step of separating the alkanone from the heavy product comprises the step of distilling the heavy product and the alkanone.  
   
   
       18 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 17  wherein the step of distilling the heavy product and the alkanone comprises the step of distilling the heavy product and the alkanone at a temperature of from 150° C. to 170° C.  
   
   
       19 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  wherein the step of introducing the amine further comprises the step of introducing the amine in an amount of from 0.1 to 10 molar equivalents of the amine compared to the aldehyde based impurities.  
   
   
       20 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  further comprising the step of adjusting a pH of the process stream.  
   
   
       21 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 20  wherein the step of adjusting the pH of the process stream comprises the step of adding an acid to the process stream.  
   
   
       22 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 1  further comprising the step of heating the process stream to a temperature of from 130° C. to 150° C.  
   
   
       23 . A method of minimizing aldehyde-based impurities in a process stream comprising cyclohexyl ketone and n-hexanal, said method comprising the steps of: 
 introducing an amine into the process stream to form a heavy product; and    distilling the cyclohexyl ketone from the heavy product.    
   
   
       24 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  wherein the step of introducing the amine comprises the step of interacting the amine with the n-hexanal to form the heavy product.  
   
   
       25 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 24  wherein the step of interacting the amine further comprises the step of chemically reacting the cyclohexyl ketone with the n-hexanal to form an alkylenyl cyclic hexanone as the heavy product.  
   
   
       26 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  wherein the amine is selected from the group of ethylenediamine, diethylenetriamine, triethylenetetramine, and combinations thereof.  
   
   
       27 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  wherein the step of introducing an amine comprises the step of injecting the amine into a distillation tower.  
   
   
       28 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  wherein the step of distilling the cyclohexyl ketone from the heavy product comprises distilling the heavy product and the cyclohexyl ketone at a temperature of from 150° C. to 170° C.  
   
   
       29 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 26  wherein the step of distilling the cyclohexyl ketone from the heavy product comprises distilling the heavy product and the cyclohexyl ketone at a temperature of from 155° C. to 165° C.  
   
   
       30 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  wherein the step of introducing the amine further comprises the step of introducing the amine in an amount of from 0.1 to 10 molar equivalents of the amine compared to the n-hexanal.  
   
   
       31 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  further comprising the step of adjusting a pH of the process stream.  
   
   
       32 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 23  further comprising the step of heating the process stream to a temperature of from 130° C. to 150° C.  
   
   
       33 . A method of minimizing aldehyde-based impurities in a process stream used in synthesis of caprolactam, the process stream comprising cyclohexyl ketone and n-hexanal, said method comprising the steps of: 
 introducing an amine into the process stream to form a heavy product; and    distilling the cyclohexyl ketone from the heavy product.    
   
   
       34 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  wherein the step of introducing the amine comprises the step of interacting the amine with the n-hexanal to form the heavy product.  
   
   
       35 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 34  wherein the step of interacting the amine further comprises the step of chemically reacting the cyclohexyl ketone with the n-hexanal to form an alkylenyl cyclic hexanone as the heavy product.  
   
   
       36 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  wherein the amine is selected from the group of ethylenediamine, diethylenetriamine, triethylenetetramine, and combinations thereof.  
   
   
       37 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  wherein the step of introducing an amine comprises the step of injecting the amine into a distillation tower.  
   
   
       38 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  wherein the step of distilling the cyclohexyl ketone from the heavy product comprises the step of distilling the cyclohexyl ketone and the heavy product at a temperature of from 150° C. to 170° C.  
   
   
       39 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 36  wherein the step of distilling the cyclohexyl ketone from the heavy product comprises the step of distilling the cyclohexyl ketone and the heavy product at a temperature of from 155° C. to 165° C.  
   
   
       40 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  wherein the step of introducing the amine further comprises the step of introducing the amine in an amount of from 0.1 to 10 molar equivalents of the amine compared to the n-hexanal.  
   
   
       41 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  further comprising the step of adjusting a pH of the process stream.  
   
   
       42 . A method of minimizing aldehyde-based impurities in a process stream as set forth in  claim 33  further comprising the step of heating the process stream to a temperature of from 150° C. to 170° C.