Method of producing lower alcohols from glycerol

Abstract

A reactive-separation process converts glycerin into lower alcohols, having boiling points less than 2000 C, at high yields. Conversion of natural glycerin to propylene glycol through an acetol intermediate is achieved at temperatures from 150° to 2500 C at pressures from 1 and 25 bar. The preferred applications of the propylene glycol are as an antifreeze, deicing compound, or anti-icing compound. The preferred catalyst for this process in a copper-chromium.

1 . A process for converting glycerol to a product at high selectivity to a mixture of acetol and propylene glycol in any combination and at low selectivity to ethylene glycol, comprising: 
       contacting a gas phase reaction mixture with a heterogeneous catalyst,
 wherein the gas phase reaction mixture contains essentially no liquid and has a partial pressure of glycerol between 0.01 and 0.5 bars of glycerol; and 
 
       establishing a temperature in a range from 80° C. to 300° C. to facilitate a reaction. 
     
     
         2 . The process of  claim 1 , wherein the gas phase reaction mixture includes hydrogen at a partial pressure of hydrogen in a range from 0.01 and 25 bars of hydrogen. 
     
     
         3 . The process of  claim 2  wherein the range of partial pressure of hydrogen is from 0.01 to 0.1 bar of hydrogen to facilitate dominantly the production of acetol product with high selectivity. 
     
     
         4 . The process of  claim 3 , comprising a step of condensing process effluent vapors to yield liquid acetol. 
     
     
         5 . The process of  claim 4 , including a step of further reacting the liquid acetol. 
     
     
         6 . The process of  claim 5 , wherein the step of further reacting includes introducing a hydrogen-containing gas to the liquid acetol at sufficient partial pressure for catalyzed reaction with the acetol to form propylene glycol as the second reaction product. 
     
     
         7 . The process of  claim 5 , wherein the temperature used in the step of further reacting is in a range between 80° C. to 150° C. 
     
     
         8 . The process of  claim 6 , further comprising a step of removing the propylene glycol from the liquid by action of the gas under conditions of partial pressure that facilitate selective removal of propylene glycol. 
     
     
         9 . The process of  claim 8 , further comprising a step of condensing the propylene glycol from the gas in a second condenser to provide liquid propylene glycol 
     
     
         10 . The process of  claim 9 , wherein the step of further reacting yields unused hydrogen and further comprising a step of recycling the unused hydrogen back to the liquid acetol. 
     
     
         11 . The process of  claim 2  wherein the range of partial pressure of hydrogen is greater than 0.1 bar to facilitate increased production of propylene glycol. 
     
     
         12 . The process of  claim 1 , wherein the heterogeneous catalyst used in the step of contacting contains at least one element from Groups I or VIII of the Periodic Table, ruthenium, copper, chromite, and combinations thereof. 
     
     
         13 . The process of  claim 1 , wherein the total pressure of reaction is between 0.02 and 25 bars. 
     
     
         14 . The process of  claim 1  where the partial pressure of glycerol is
 less than glycerol's dew point partial pressure in the reaction mixture and   greater than one fourth the dew point partial pressure in the reaction mixture.   
     
     
         15 . The process of  claim 14  where the partial pressure of glycerol is greater than half the dew point partial pressure in the reaction mixture. 
     
     
         16 . The process of  claim 1 , wherein the temperature used in the step of establishing is in a range from 150° C. to 250° C. 
     
     
         17 . The process of  claim 1 , wherein the temperature used in the step of establishing is in a range from 185° C. to 240° C. 
     
     
         18 . The process of  claim 1  wherein the gas phase reaction mixture contains water in an amount of 1 part by mass water for every 0.333 to 1 parts glycerol and hydrogen is present at a hydrogen to glycerol molar ratio between 0.1:1 and 15:1. 
     
     
         19 . The process  claim 18 , wherein the temperature used in the step of establishing is in a range between 250° C. to 300° C. 
     
     
         20 . The process of  claim 1 , wherein the partial pressure of hydrogen used in the step of contacting is in a range from 3 to 25 bars of hydrogen. 
     
     
         21 . The process of  claim 1 , wherein the partial pressure of hydrogen used in the step of contacting is in a range from 0.1 to 5 bars of hydrogen. 
     
     
         22 . A system for converting glycerol to a product at high selectivity to a mixture of acetol and propylene glycol in any combination and at low selectivity to ethylene glycol, comprising: 
       means for contacting a gas phase reaction mixture with a heterogeneous catalyst,
 wherein the gas phase reaction mixture contains essentially no liquid and has a partial pressure of glycerol between 0.01 and 0.5 bars of glycerol; and 
 
       means for establishing a temperature in a range from 80° C. to 300° C. to facilitate a reaction. 
     
     
         23 . The system of  claim 22 , wherein the means for contacting includes means for providing the gas phase reaction mixture with hydrogen at a partial pressure of hydrogen in a range from 0.01 and 25 bars of hydrogen. 
     
     
         24 . The system of  claim 23  wherein the range of partial pressure of hydrogen is from 0.01 to 0.1 bar of hydrogen to facilitate dominantly the production of acetol product with high selectivity. 
     
     
         25 . The system of  claim 24 , comprising a means for condensing process effluent vapors to yield liquid acetol. 
     
     
         26 . The system of  claim 25 , including means for further reacting the liquid acetol. 
     
     
         27 . The system of  claim 26 , wherein the means for further reacting includes means for introducing a hydrogen-containing gas to the liquid acetol at sufficient partial pressure for catalyzed reaction with the acetol to form propylene glycol as the second reaction product. 
     
     
         28 . The system of  claim 27 , wherein the temperature used in the means for further reacting is in a range between 80° C. to 150° C. 
     
     
         29 . The system of  claim 27 , further comprising means for removing the propylene glycol from the liquid by action of the gas under conditions of partial pressure that facilitate selective removal of propylene glycol. 
     
     
         30 . The system of  claim 29 , further comprising means for condensing the propylene glycol from the gas in a second condenser to provide liquid propylene glycol 
     
     
         31 . The system of  claim 29 , wherein the means for further reacting yields unused hydrogen and further comprising means for recycling the unused hydrogen back to the liquid acetol. 
     
     
         32 . The system of  claim 22  wherein the range of partial pressure of hydrogen is greater than 0.1 bar to facilitate increased production of propylene glycol. 
     
     
         33 . The system of  claim 22  wherein the heterogeneous catalyst used in the means for contacting contains at least one element from Groups I or VIII of the Periodic Table, ruthenium, copper, chromite, and combinations thereof. 
     
     
         34 . The system of  claim 22 , wherein the total pressure of reaction is between 0.02 and 25 bars. 
     
     
         35 . The system of  claim 22  where the partial pressure of glycerol is
 less than glycerol's dew point partial pressure in the reaction mixture and   greater than one fourth the dew point partial pressure in the reaction mixture.   
     
     
         36 . The system of  claim 35  where the partial pressure of glycerol is greater than half the dew point partial pressure in the reaction mixture. 
     
     
         37 . The system of  claim 22 , wherein the temperature used in the means for establishing is in a range from 150° C. to 250° C. 
     
     
         38 . The system of  claim 22 , wherein the temperature used in the means for establishing is in a range from 185° C. to 240° C. 
     
     
         39 . The system of  claim 22 , wherein the gas phase reaction mixture contains water in an amount of 1 part by mass water for every 0.333 to 1 parts glycerol and hydrogen is present at a hydrogen to glycerol molar ratio between 0.1:1 and 15:1. 
     
     
         40 . The system  claim 39 , wherein the temperature used in the means for establishing is in a range between 250° C. to 300° C. 
     
     
         41 . The system of  claim 22 , wherein the partial pressure of hydrogen used in the means for contacting is in a range from 3 to 25 bars of hydrogen. 
     
     
         42 . The system of  claim 22 , wherein the partial pressure of hydrogen used in the means for contacting is in a range from 0.1 to 5 bars of hydrogen.