Pretreating cellulosic biomass

A device for removing one or more aromatic compounds from a cellulosic biomass comprising:

• A vessel having a chamber, a port, means for introducing a near critical, critical or supercritical fluid, means for explosively decompressing said near critical, critical or supercritical fluid with or without a polar cosolvent to form a aromatic fluid;
• said chamber for containing a cellulosic biomass having one or more aromatic compounds, said port having an open position for receiving a said cellulosic biomass having one or more aromatic compounds and a closed position in which said chamber is substantially closed, said means for introducing a near critical, critical or super critical fluid with or without a polar cosolvent in communication with at least one near critical, critical or supercritical fluid with or without a polar cosolvent, said means for explosively decompressing said critical, near critical or supercritical fluid capable of rapidly reducing pressure in said chamber;
• A recycling loop in fluid communication with said means for explosively decompressing said near critical, critical or supercritical fluid with or without a polar cosolvent to receive said aromatic fluid, said recycling loop separating said aromatic compounds from said aromatic fluid to form a non-critical fluid and one or more aromatic compounds;
• Critical fluid means for changing at least one of the group selected from temperature, pressure or constituents to make said non-critical fluid a near critical, critical or supercritical fluid with or without a polar cosolvent, said critical fluid means in communication with said recycling loop to receive said non-critical fluid and in communication with said means for introducing a near critical, critical or super critical fluid, said vessel receiving a biomass having one or more aromatic compounds in said chamber and forming a fluidized biomass with said near critical, critical or supercritical fluid with or without a polar cosolvent, and upon explosive decompression a aromatic fluid and a disrupted biomass, said aromatic fluid received in said recycling loop to form a aromatic compound and a non-critical fluid, said non-critical fluid received by said critical fluid means and processed to make a critical, near critical or supercritical fluid with or without a polar cosolvent to be received in said chamber.