A process to perform a controlled exothermic delignification of biomass comprises providing a system having a first vessel and a second vessel, providing a biomass comprising lignin, hemicellulose and cellulose fibers placed into the first vessel, providing an aqueous acidic composition comprising a sulfuric acid component, providing a modifier component and providing a peroxide component. The biomass is exposed to the sulfuric acid component and peroxide component, thereby creating a reaction mass. The reaction mass is mixed and the sulfuric acid, modifier and peroxide components are allowed to come into contact with the biomass for a period of time sufficient for a delignification reaction to occur and to remove a predetermined amount of the lignin from the biomass. The predetermined amount is assessed by testing a first kappa number of the biomass. When the first kappa number of the biomass is reached, the biomass is transferred to the second vessel.

The invention relates to a method for producing products based on non-woody biomass as raw material, characterised in that non-woody biomass which contains cellulose, hemicelluloses and lignin and is in the form of particles is subjected to an extraction treatment with an extractant which comprises one or more organic solvents in an organic aqueous mixture of the solvent or solvents with water, wherein the content of fatty acids in the particles is reduced by the extraction treatment of the particles with the solvent by at least 70%, measured as hexanal content in wt. % after accelerated ageing for 72 hours at 90? C., but the content of cellulose, hemicelluloses and lignin is substantially preserved in this extraction treatment.

In one example, a process includes providing a system with a first vessel and a second vessel; providing a biomass comprising lignin, hemicellulose and cellulose fibers into said first vessel; providing an aqueous acidic composition comprising an acid; providing a modifier component; providing a peroxide component; exposing said biomass to said sulfuric acid, modifier and peroxide components, creating a reaction mass; mixing said reaction mass; and allowing said sulfuric acid component and peroxide component to come into contact with said biomass for a period of time sufficient to a delignification reaction to occur and remove a pre-determined amount of said lignin from said biomass. The pre-determined amount may be 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 biomass is transferred to said second vessel.

A process to perform a controlled exothermic delignification of biomass comprises providing a system having a first vessel and a second vessel, providing a biomass comprising lignin, hemicellulose and cellulose fibers placed into the first vessel, providing an aqueous acidic composition comprising a sulfuric acid component, providing a modifier component and providing a peroxide component. The biomass is exposed to the sulfuric acid component and peroxide component, thereby creating a reaction mass. The reaction mass is mixed and the sulfuric acid, modifier and peroxide components are allowed to come into contact with the biomass for a period of time sufficient for a delignification reaction to occur and to remove a predetermined amount of the lignin from the biomass. The predetermined amount is assessed by testing a first kappa number of the biomass. When the first kappa number of the biomass is reached, the biomass is transferred to the second vessel.