Optimization of chemical consumption in biomass delignification

1 . A process to perform a controlled exothermic delignification on a batch of lignocellulosic biomass, said process comprising:

providing a system comprising at least a first vessel and a second vessel;

providing biomass comprising lignin, hemicellulose and cellulose fibers into said first vessel;

providing an aqueous acidic composition comprising an acid selected from the group consisting of: sulfuric acid; an alkylsulfonic acid; an arylsulfonic acid and combinations thereof;

providing a modifier component;

providing a peroxide component;

exposing said biomass to said acidic composition, said peroxide component and said modifier component to create a reaction mass;

mixing said reaction mass;

allowing said acidic composition and peroxide component to come into contact with said biomass for a period of time sufficient for a delignification reaction to occur and remove a pre-determined amount of said lignin from said biomass to form a first treated biomass, wherein said pre-determined amount is assessed by determining a first remaining peroxide concentration in the reaction mass, with a suitable apparatus, when said first remaining peroxide concentration is reached, the first treated biomass is transferred to said second vessel;

allowing a temperature of the first treated biomass to increase during the residence time of said first treated biomass in said second vessel to a second temperature; and

allowing said acidic composition, said modifier component and said peroxide component to continue said delignification reaction at said second temperature and remove a second pre-determined amount of said lignin from said first treated biomass to form a second treated biomass, wherein said second pre-determined amount is assessed by testing a second remaining peroxide concentration in the first treated biomass, when said second remaining peroxide concentration is reached, the second treated biomass is removed from said second vessel.

2 . The process according to claim 1 , wherein said system comprises a third vessel where the second treated biomass is sent to after being removed from said second vessel, and further comprising:

allowing the temperature of the second treated biomass to increase during the residence time of said second treated biomass in said third vessel to a third temperature; and

allowing said acidic composition, said modifier component and said peroxide component to continue said delignification reaction at said third temperature and remove a third pre-determined amount of said lignin from said biomass to form a third treated biomass, wherein said third pre-determined amount is assessed by testing a third remaining peroxide concentration in the second treated biomass, when said third remaining peroxide concentration in said second treated biomass is reached, the third treated biomass is removed from said third vessel.

3 . The process according to claim 2 , where said process requires temperature control at said first vessel, and said second vessel.

4 . The process according to claim 3 , where said temperature control comprises a heat exchanger, jacketed vessel and baffles.

5 . The process according to claim 4 , where said temperature control is a heat exchanger, secondary control is a jacketed tank and tertiary control is a baffle.

6 . The process according to claim 5 , where said system has an outlet which allows the separation of solids from liquids.

7 . The process according to claim 6 , where said mixing in said first vessel is performed by a recirculation of the reaction mass.

8 . The process according to claim 7 , further comprising mixing the first treated biomass in said second vessel using a first paddle mixer.

9 . The process according to claim 8 , further comprising mixing the second treated biomass in said third vessel using a second paddle mixer.

10 . The process according to claim 1 , where said aqueous acidic composition, said modifier component and said peroxide component collectively form a modified Caro's acid composition selected from the group consisting of composition A; composition B and Composition C;

wherein said composition A comprises:

sulfuric acid in an amount ranging from 20 to 70 wt % of the total weight of the composition;

a modifier component comprising an amine moiety and a sulfonic acid moiety selected from the group consisting of taurine; taurine derivatives; and taurine-related compounds; and

a peroxide;

wherein said composition B comprises:

an alkyl sulfonic acid; and

a peroxide; wherein the acid is present in an amount ranging from 40 to 80 wt % of the total weight of the composition and where the peroxide is present in an amount ranging from 10 to 40 wt % of the total weight of the composition;

wherein said composition C comprises:

sulfuric acid; and

a two-part modifier component comprising:

a compound comprising an amine moiety;

a compound comprising a sulfonic acid moiety; and

a peroxide.

11 . The process according to claim 1 , where the temperature of the reaction mass is maintained at a temperature ranging from 25-45° C.

12 . The process according to claim 1 , wherein at least part of the resulting liquid portion after coming out of the first is used to treat at least one additional biomass batch.

13 . The process according to claim 1 , wherein at least part of the resulting liquid portion after coming out of the second vessel is used to treat at least four additional biomass batches.

14 . The process according claim 1 , wherein at least part of the resulting liquid portion after coming out of the second vessel obtained at the end of the reaction is used to further treat additional biomass batches until the peroxide concentration reaches less than 1%.

15 . The process of claim 1 , further comprising a washing step to separate a resulting liquid portion comprising said lignin and hemicellulose from the solid portion containing the cellulose extracted from the biomass.