Catalytic pyrolysis of biomass in an auger reactor

Abstract

The present invention relates generally to the thermal conversion of biomass. Processes are disclosed for converting algal biomass to condensable vapor intermediates such as pyrolysis oil by means of pyrolysis in a reactor comprising at least one auger. The intermediates may be further processed for production of renewable hydrocarbon fuels. The disclosed processes assist in preventing premature devolatization of algal biomass during pyrolysis, thereby increasing efficiency and commercial feasibility.

1 . A process comprising:
 (a) providing a thermal reactor comprising at least one auger, and a first mixture comprising a heat carrier and at least one catalyst;   (b) introducing a feedstock comprising biomass to the thermal reactor and contacting therein with the first mixture to produce a second mixture,
 wherein at least a portion of the feedstock is converted to condensable vapor intermediates via pyrolysis, 
 wherein the catalyst facilitates the rate at which the feedstock is converted, 
 wherein rotation of the at least one auger increases heat transfer from the heat carrier to the feedstock and increases contact between the feedstock and the first mixture, 
   (c) conveying the second mixture through the reactor for a defined residence time prior to removal from the reactor.   
     
     
         2 . The process of  claim 1 , wherein said thermal reactor is maintained at a pressure in a range from about 50 psig to about 500 psig and a temperature in a range from about 250° C. to about 1000° C. 
     
     
         3 . The process of  claim 1 , wherein said thermal reactor is maintained at a pressure in a range from about 15 psig to about 50 psig and a temperature in a range from about 350° C. to about 700° C. 
     
     
         4 . The process of  claim 1 , wherein upon introducing the feedstock to the reactor, the feedstock is heated at a rate from about 100° C. per second to about 10,000° C. per second. 
     
     
         5 . The process of  claim 1 , wherein the first mixture is introduced at a first location that is proximal to a reactor first end and is conveyed by the at least one auger to a second location located downstream, wherein the feedstock is introduced at the second location and combines with the first mixture to form a second mixture. 
     
     
         6 . The process of  claim 1 , wherein the feedstock is introduced at a first location that is proximal to a reactor first end and is conveyed by the at least one auger to a second location located downstream, wherein the first mixture is introduced at the second point and combines with the feedstock to form a second mixture 
     
     
         7 . The process of  claim 1 , wherein the defined residence time is decreased as a result of step (b) 
     
     
         8 . The process of  claim 1 , wherein the heat carrier and the at least one catalyst are particulate solids, thereby increasing the surface area available for direct contact with the feedstock. 
     
     
         9 . The process of  claim 1 , wherein the at least one catalyst increases the rate of pyrolysis, such that the temperature required for pyrolysis is lowered, the required residence time of the feedstock is decreased, or combinations thereof. 
     
     
         10 . The process of  claim 1 , wherein the feedstock is converted in an atmosphere comprising an inert gas and less than 0.5 mol % oxygen gas. 
     
     
         11 . The process of  claim 1 , wherein the feedstock is converted to condensable vapor intermediates in the presence of a reactive gas selected from a group consisting of hydrogen, synthesis gas (i.e., CO +H2), steam/water, ammonia, methane, ethane, propane, butane, pentane, and natural gas, etc., and any combinations thereof. 
     
     
         12 . The process of  claim 1 , wherein rotation of the at least one auger increases contact between the heat carrier and the feedstock to increase the heating rate of the feedstock. 
     
     
         13 . The process of  claim 1 , wherein rotation of the at least one auger increases contact between the catalyst and the feedstock to increase the catalytic pyrolysis of the feedstock. 
     
     
         14 . The process of  claim 1 , wherein the at least one catalyst comprises at least one of Co, Ni, Mo, W, Zn, Ga a zeolite, a metal-impregnated zeolite, and combinations thereof.