Optimizing chemical consumption in biomass delignification

Abstract

1. A process for performing controlled exothermic delignification of biomass, the process comprising: - providing a system comprising at least a first vessel and a second vessel; - providing biomass comprising lignin, hemicellulose, and cellulose fibers to the first vessel; - providing an aqueous acidic composition comprising a sulfuric acid component; - providing a modifier component; - providing a peroxide component; - exposing the biomass to the sulfuric acid, modifier, and peroxide components to form a reaction mass; - mixing the reaction mass; and - contacting the sulfuric acid, modifier, and peroxide components with the biomass for a period of time sufficient to cause a delignification reaction to occur and remove a predetermined amount of the lignin from the biomass, the predetermined amount being assessed by testing a first kappa number of the biomass using a suitable device, and transferring the biomass to the second vessel upon reaching the first kappa number of the biomass.

Description

[Technical Field]

[0001] The present invention relates to a method and system for pulping biomass (called "chips") in a treatment vessel, and more particularly to a method and system for carrying out a continuous pulping process under low operating conditions. [Background technology]

[0002] Petroleum- or fossil-fuel-based products include a vast number of products, such as surfactants, pharmaceuticals, plastics, and elastomers, which are abundant in all aspects of the production of consumer products and fuels used to power vehicles, homes, and industries. Climate change and environmental pressures are forcing society to find alternatives to fossil fuels and petroleum-based products. A well-known source of non-petroleum-based products is lignocellulosic biomass, which is the single most abundant source of carbon-neutral organic material on Earth and contains the majority of compounds necessary to sustain multiple industries, including, but not limited to, energy production, chemicals, food, pharmaceuticals, concrete, various manufacturing, and agricultural applications.

[0003] Billions of tons are produced annually through biosynthesis. However, efficiently separating the three components of lignocellulosic biomass has proven challenging for it to be a viable competitor or alternative to petroleum-based products. To benefit from and further utilize lignocellulosic biomass, it is necessary to be able to separate lignin from hemicellulose and cellulose. Cellulose is an abundant, high-molecular-weight natural fiber with great strength and biodegradability. Depending on the feedstock, cellulose can comprise 30–60 percent or sometimes more of plant material and is found in tree / forestry residues, algae, crops, straw, municipal and industrial waste, and various plants.

[0004] Furthermore, due to the encasement of cellulose between lignin and hemicellulose, efficient and commercially viable extraction of cellulose is highly dependent on the method and biomass source used during the extraction process. Many current and proposed processing methods can limit the use of cellulose or alter its structural integrity, resulting in marginal yields and excessive processing costs. Generally, cellulose extracted from plant materials contains both amorphous and crystalline regions.

[0005] It is widely agreed that technical difficulties in currently inefficient, expensive, and difficult-to-scale processes for separating lignin and hemicellulose from cellulose in biomass prevent such technologies from being viable alternatives to petroleum-based or fossil fuel products.

[0006] The first step in paper production, and one of the most energy-intensive, is the production of pulp. Despite the use of water, wood, and other plant materials, pulp contains three main components: cellulose fiber, lignin, and hemicellulose. Pulping primarily aims to separate the fiber from the lignin. Lignin is a three-dimensional cross-linked polymer that figuratively acts as mortar to hold all the fibers together within the plant. Its presence in the finished pulp is undesirable and adds nothing to the finished product. Wood pulping refers to the breakdown of the bulk structure of the fiber source, whether it be chips, stems, or other plant parts, into its constituent fibers. Cellulose fiber is the most desired component when papermaking is involved. Hemicellulose is a shorter, branched carbohydrate polymer composed of various monosaccharides (monosacharides) that form a random, amorphous polymer structure. Because biomass conversion requires further breakdown into monosaccharides (monosacharides) as a desired outcome, the presence of hemicellulose after biomass conversion is less desirable; however, the pulp and paper process usually stops immediately after lignin dissolution. In fact, hemicellulose is desirable in the finished pulp because it acts like a glue for the cellulose fibers during papermaking.

[0007] There are two main approaches to preparing wood pulp or woody biomass: mechanical and chemical. Mechanical processing, or pulping, generally involves mechanically tearing wood chips, thus tearing the cellulose fibers apart in an attempt to separate them from one another. Disadvantages of this approach include broken cellulose fibers (and therefore shorter fibers) and lignin remaining on the cellulose fibers, making it inefficient or suboptimal. This process also consumes large amounts of energy and requires significant capital. Chemical pulping encompasses several techniques, generally aimed at breaking down lignin and hemicellulose into small, water-soluble molecules. These decomposed components can be separated from the cellulose fibers by washing and filtering them, without depolymerizing them. Chemical processes are currently energy-intensive, typically requiring large amounts of heat and / or higher pressures, and often also require agitation or mechanical intervention, further adding inefficiency and cost to the process.

[0008] Pulping or treatment methods exist that combine, to varying degrees, the chemical aspect of pulping with the mechanical aspect of pulping. To name a few, consider thermomechanical pulping (also commonly referred to as TMP) and chemi-thermomechanical pulping (CTMP). By selecting the benefits offered by each common pulping method, treatments are designed to reduce the amount of energy required by the mechanical aspect of the pulping treatment. This, in turn, can have a direct impact on the degradation of strength or tensile strength of fibers subjected to these combined pulping techniques. Generally, these approaches involve a shortened chemical treatment (compared to traditional, exclusively chemical pulping), which is then typically followed by a mechanical treatment to separate the fibers.

[0009] The most common process for producing pulp for paper production is the Kraft process. In the Kraft process, wood chips are converted almost entirely into wood pulp, which is a pure cellulose fiber. The multi-stage Kraft process consists of the first step of impregnating / treating the wood chips with a chemical solution. This is done by soaking the wood chips and then preheating them with steam. This step swells the wood chips, expelling any air present within the chips and replacing the air with liquid. This produces black liquor, a by-product of the Kraft process. It contains water, lignin residues, hemicellulose, and inorganic chemicals. White liquor is a strong alkaline solution containing sodium hydroxide and sodium sulfide. Once the wood chips are soaked in the various chemical solutions, they are then cooked. To achieve delignification in the wood chips, cooking is carried out at temperatures up to 176°C for several hours. At these temperatures, the lignin breaks down to produce water-soluble fragments. After the cooking step, the remaining cellulosic fiber is collected and washed.

[0010] U.S. Patent No. 5,080,756 teaches an improved kraft pulping process, characterized in that a spent concentrated sulfuric acid composition containing organic matter is added to a kraft recovery system to provide a mixture enriched in its total sulfur content, which is subjected to dehydration, pyrolysis, and reduction in a recovery furnace. The organic matter of the sulfuric acid composition is particularly useful as a thermal energy source, making it easier to maintain high heat levels to promote the oxidation and reduction reactions occurring in the furnace, thus resulting in the formation of sulfides used to prepare a cooking liquor suitable for pulping.

[0011] Caro's acid, also known as peroxymonosulfuric acid (H2SO5), is one of the most powerful oxidizing agents known. While several reactions are known for the preparation of Caro's acid, one of the most straightforward involves the reaction between sulfuric acid (H2SO4) and hydrogen peroxide (H2O2). Preparing Caro's acid in this manner allows for further reaction to yield potassium monopersulfate (PMPS), a valuable bleaching and oxidizing agent. Caro's acid has several known useful applications, most notably its use in wood delignification. For bagasse pulping, it has been proposed as part of a two-stage pulping technique (a sodium hydroxide stage followed by a Caro's acid stage) or a three-stage pulping technique (a sodium hydroxide stage followed by a Caro's acid stage followed by another sodium hydroxide stage).

[0012] Other methods for pretreating lignocellulosic feedstocks have been developed. These pretreatment methods include dilute acid pretreatment, steam explosion (CO2 explosion), pH-controlled water pretreatment, ammonia fiber swelling, ammonia recycle percolation (ARP), and lime pretreatment (Mosier et al. 2005; Wyman et al. 2005; Yang and Wyman 2008). One approach involves the organosolv concept. Organosolv pulping is a process in which lignin is extracted from lignocellulosic feedstocks using organic solvents or their aqueous solutions. Organosolv pulping has attracted attention since the 1970s because traditional pulping processes, the kraft and sulfite processes, have several significant drawbacks, such as air and water pollution. Organosolv pretreatment is similar to organosolv pulping, but the degree of delignification for pretreatment is not expected or required to be as high as that for pulping. However, a drawback of organosolv pretreatment is that the process is known to be high temperature, occurring at temperatures above 100-250°C, often in the range of 185-210°C. Such temperatures require high energy input.

[0013] Improved processes for delignification must consider environmental aspects as well as end-product generation. Ambient temperature processes (20-25°C) are highly desirable because they do not require energy-intensive inputs. However, strong acids are typically required to perform delignification operations at low temperatures and atmospheric pressure. While sufficient to remove lignin present in lignocellulosic feedstocks, the strength of the acids used can be detrimental to the lignin, as it degrades beyond any lignin monomers that can be used in other industries or applications. They can also damage the resulting cellulose, thus preventing the delivery of usable products from the feedstock. A common drawback of using strong acids on cellulose is the darkening of the cellulose. The acid acts as a dehydrating agent, removing water molecules from the cellulose and leaving carbon residues in a highly exothermic reaction, indicating that the glucose units present in the cellulose have been destroyed, leaving carbon behind.

[0014] Biofuel production is another potential application of the Kraft process. One of the current drawbacks of biofuel production is that it requires the use of food-grade plant parts (such as seeds) to convert carbohydrates into fuel in a reasonably efficient process. While monosaccharides (primarily glucose) could be obtained from cellulosic fibers by using non-food-grade biomass in the Kraft process, the energy-intensive nature of the Kraft process for delignification makes this a commercially viable option. To build a plant-based chemical resource cycle, there is a great need for energy-efficient processes that can utilize plant-based feedstocks that do not compete with human food production.

[0015] In addition to cellulose recovery, lignin recovery is becoming increasingly important. Most conversion technologies involving dissolved lignin use heat and metal catalysts to effectively decompose lignin into low-molecular-weight aromatics, which hold value for other uses / applications across industries. Some considerations to take into account when exploring various processes include the efficiency of the catalyst used; catalyst stability; catalyst selectivity; and control of lignin condensation and repolymerization reactions. Lignin condensation and repolymerization often result in products that cannot be easily decomposed using conventional techniques, thus resulting in significant loss of value for future industrial uses / applications. Lignin condensation and repolymerization directly impact the recovery of target lignin products (such as low-molecular-weight phenolic compounds). Therefore, it is important to avoid condensation and repolymerization reactions to maximize the yield of target products.

[0016] Lignin repolymerization has been a substantial concern at many stages of the process for delignification of lignocellulosic biomass. Traditional fractionation processes, i.e., biomass pretreatment, generally employ acid or base catalysts and focus on their effectiveness in removing lignin from the biomass structure. The resulting residual solids, primarily lignin, undergo significant irreversible repolymerization depending on the pretreatment conditions. This is an outcome that must be avoided to extract the maximum value from treatments aimed at recovering both cellulose and lignin for future use.

[0017] The kraft pulping process is the most widely used chemical pulping process in the world, but it is very energy intensive and has many drawbacks (e.g., significant odors emitted around pulp production mills or general emissions that are now highly regulated in many pulp and paper production jurisdictions). In light of current environmental, economic, and climate change trends, as well as implemented emission fees, it is highly desirable to optimize current pulping processes to provide at least linear quality fiber without currently causing substantial damage to the environment during its production. Therefore, there remains a need for compositions that can perform delignification of woody materials at low temperatures and reduced pressures relative to those currently used, without requiring any additional capital investment.

[0018] Therefore, there remains a need for a system and process that can carry out delignification of lignocellulosic biomass at lower temperatures and pressures compared to those currently in use without requiring any significant additional capital expenditures that are adapted to preserve as much as possible of the lignocellulosic biomass components for further use. The inventors have developed an improved delignification system and process that is more in line with the increasing environmental constraints and regulations implemented by governments around the world. Summary of the Invention

[0019] According to a preferred embodiment of the present invention, the process utilizes a chemical impregnation process of biomass with a chemical blend that uses the heat of reaction (reaction enthalpy) released during the reaction to raise the temperature of the reaction mixture. Preferably, there is little or no external heat input to the reaction mixture. This distinguishes the process from conventional pulping processes such as kraft pulping.

[0020] It has been unexpectedly discovered by the present inventors that by separating the delignification process into separate steps, it is possible to achieve a more efficient consumption of the chemicals used in the delignification reaction, as well as to shorten the reaction time to achieve complete or substantially complete delignification under conditions that are substantially less energy intensive than those traditionally employed in processes such as kraft pulping. According to a preferred embodiment of the present invention, the consumption of peroxide was such that the initial concentration of peroxide in the reaction mass was in the range of approximately 10%, and after the reaction, the concentration of peroxide was approximately 2%. Without a continuous process as described in this invention, peroxide consumption would be much lower, thereby resulting in a greater amount of such being wasted and therefore higher operating and associated costs.

[0021] According to a preferred embodiment of the present invention, the process utilizes a system comprising a single reactor separated into multiple stages. Preferably, the process utilizes a system comprising a single reactor separated into several stages, ranging from 2 to 6 stages. More preferably, the process utilizes a system comprising a single reactor separated into three stages.

[0022] Each stage contains various components, but these components are more easily distinguished by their residence time, which is primarily determined by the kappa number that must be achieved to proceed to the subsequent stage. Kappa number is a measure of the residual lignin content obtained after pulping. It is used to evaluate the effectiveness of a pulping stage, which typically results in partial delignification of the pulp. The degree of delignification is measured to determine the amount of chemicals required before performing a bleaching step on the pulp in conventional processes such as kraft. For example, the kappa number of bleachable pulp typically ranges from 25 to 30, while the kappa number of pulp used to make corrugated board (cardboard) typically ranges from 60 to 110.

[0023] The kappa number is evaluated using an online kappa analyzer. An advanced process control system equips the reactor with the necessary control strategy. This control system links the information transmitted by the kappa number analyzer, the temperature, and the residence time, and adjusts the process variables according to the set points and the transfer of reactants from one stage to the next. Implementation of this system and the associated process makes it possible to achieve complete or substantially complete delignification of the input biomass. Preferably, when the process control is optimized and the transfer of the reaction mixture between the reaction vessels is performed seamlessly, the system functions like a continuous process reactor.

[0024] According to a preferred embodiment of the present invention, there is provided a system comprising at least two vessels adapted to receive biomass and delignification liquor, the at least two vessels being arranged in series.

[0025] According to a preferred embodiment of the present invention, there is provided a system for continuous delignification of biomass. Preferably, the system comprises at least two in-line vessels in which the delignification reaction occurs. Preferably, the system comprises a first vessel operating at a first temperature, in which the biomass having a first kappa number is mixed with a delignification composition for a predetermined time or until the biomass reaches a second predetermined kappa number. Preferably, once the biomass reaches the second predetermined kappa number, the biomass is transferred to a second vessel where the delignification reaction is carried out at a second temperature set slightly higher than the first temperature to accelerate the reaction by increasing the reaction rate. The biomass having the second kappa number continues to be mixed with the delignification composition for a predetermined time or until the biomass reaches a third predetermined kappa number. Preferably, once the biomass reaches the third predetermined kappa number, the biomass is transferred to a third vessel where the delignification reaction is carried out at a third temperature set slightly higher than the second temperature. The biomass having the third kappa number continues to be mixed with the delignification composition for a predetermined time or until the biomass reaches a predetermined fourth and final kappa number. Preferably, once the biomass reaches the fourth predetermined kappa number, the reaction mixture is then discharged, the solid portion is separated from the liquid portion, and the liquid is recovered and re-injected into the process by injection into the first vessel for use in peroxide consumption.

[0026] In accordance with a preferred embodiment of the present invention, the system further comprises a temperature indicator / controller designed to monitor changes in temperature setpoint and provide data to an APC [Advanced Process Control] to maintain desired conditions.

[0027] According to a preferred embodiment of the present invention, the system further comprises a spray nozzle in the central main piping system designed to provide mixing of the biomass and chemical solution within the container.

[0028] According to a preferred embodiment of the present invention, the system further comprises a chemical extraction screen designed to extract the chemical from the container and pump it to the spray nozzle and external heat exchanger.

[0029] In accordance with a preferred embodiment of the present invention, the system further comprises a heating / cooling jacket designed to be a secondary temperature control method for maintaining a temperature set point.

[0030] In accordance with a preferred embodiment of the present invention, the system further comprises an actuated discharge valve designed to discharge the product slurry to a next stage upon satisfaction of the in-line analyzer or based on a predetermined time.

[0031] In accordance with a preferred embodiment of the present invention, the system further comprises a heat exchanger designed to be the primary method for cooling or heating the solution to a desired set point.

[0032] In accordance with a preferred embodiment of the present invention, the system further comprises a central main piping system, which is a piping system designed to distribute chemical solutions to the biomass and chemical blend within the vessel.

[0033] According to a preferred embodiment of the present invention, the system further comprises a kappa analyzer at each stage / vessel to determine the pulping rate of the biomass.

[0034] In accordance with a preferred embodiment of the present invention, the system further comprises at least one tank baffle designed to increase mixing efficiency as well as increase cooling / heating surface area by acting as a tertiary temperature control by allowing hot / cold fluid to enter through the baffle.

[0035] In accordance with a preferred embodiment of the present invention, the system further comprises a cone bottom, which is desirable to make it easier for the reaction mixture to be discharged from one vessel to the next.

[0036] According to a preferred embodiment of the present invention, the system further comprises a top-mounted agitator designed to provide the desired agitation to the reaction mixture.

[0037] According to yet another aspect of the present invention, there is provided a process for delignifying biomass, the process comprising: - providing a container; - providing a biomass containing lignin, hemicellulose, and cellulose fibers in said vessel; - providing an aqueous acidic composition comprising a sulfuric acid component; - providing a modifier component; - providing a peroxide component; - exposing the biomass to the sulfate source and peroxide component to form a reaction mass; - contacting the sulfuric acid source and peroxide component with the biomass for a time sufficient to cause a delignification reaction to occur and remove greater than 90% by weight of the lignin and hemicellulose from the biomass; - controlling the temperature of the delignification reaction by controlling the addition of biomass to the vessel.

[0038] According to yet another aspect of the present invention, there is provided a process for carrying out controlled exothermic delignification of biomass, the process comprising: - providing a system comprising at least a first container and a second container; - providing the biomass, including lignin, hemicellulose, and cellulose fibers, in the first vessel; - providing an aqueous acidic composition comprising a sulfuric acid component; - providing a modifier component; - providing a peroxide component; - exposing the biomass to the sulfate and peroxide components to form a reaction mass; - mixing the reaction mass; - contacting the sulfuric acid component and the peroxide component with the biomass for a period of time sufficient to cause a delignification reaction to occur and remove a predetermined amount of the lignin from the biomass; contacting the sulfate and peroxide components with the biomass, wherein the predetermined amount is assessed by testing a first kappa number of the biomass with a suitable device, and when the first kappa number of the biomass is reached, the biomass is transferred to the second vessel; - increasing the temperature of the biomass mixture during the residence time of the biomass in the second vessel; - allowing the sulfuric acid component and the peroxide component to continue the delignification reaction at the second temperature to remove a second predetermined amount of the lignin from the biomass; allowing the removal of a second predetermined amount of the lignin from the biomass, wherein the second predetermined amount is assessed by testing a second kappa number of the biomass using a suitable device, and the biomass is removed from the second vessel once the second kappa number of the biomass is reached; - optionally using a washing step to separate the resulting liquid portion comprising the lignin and hemicellulose from the solid portion comprising the cellulose extracted from the biomass.

[0039] Preferably, the system comprises a third vessel into which the biomass is sent after being removed from the second vessel; - increasing the temperature of the biomass mixture during the residence time of the biomass in the second vessel; - allowing the sulfuric acid component and the peroxide component to continue the delignification reaction at the second temperature to remove a third predetermined amount of the lignin from the biomass; The third predetermined amount is assessed by testing the biomass for a third kappa number using a suitable device, and once the third kappa number of the biomass is reached, the biomass is removed from the third vessel, allowing a third predetermined amount of the lignin to be removed from the biomass.

[0040] According to a preferred embodiment of the present invention, the temperature of the reaction mass is maintained below 55°C throughout the delignification reaction. Preferably, the temperature of the reaction mass is maintained below 50°C throughout the delignification reaction. Preferably, the temperature of the reaction mass is maintained below 45°C throughout the delignification reaction. Preferably, the reaction temperature is controlled in the range of 30-45°C to achieve optimal reaction time and at least 90% delignification. According to a preferred embodiment of the present invention, the temperature of the reaction mass is maintained below 55°C as the maximum head temperature, noting that above this temperature the reaction tends to runaway and becomes more difficult to control with external temperature control. If the reaction temperature increases too quickly, it may be necessary to add water to control or stop the reaction. Preferably, the reaction temperature is maintained between 30-45°C, even more preferably between 35-40°C.

[0041] According to a preferred embodiment of the present invention, the initial temperature of the reaction mass is not more than 40°C and does not exceed 55°C during the delignification reaction. Preferably, the initial temperature of the reaction mass is not more than 35°C and does not exceed 55°C during the delignification reaction. More preferably, the initial temperature of the reaction mass is not more than 30°C and does not exceed 55°C during the delignification reaction. Also preferably, the initial temperature of the reaction mass is not more than 25°C and does not exceed 55°C during the delignification reaction.

[0042] According to a preferred embodiment of the present invention, the temperature of the reaction mass is controlled throughout the delignification reaction and subsequent addition of solvent (water) to gradually decrease the gradient of temperature increase per minute from less than 1°C / min to less than 0.5°C / min.

[0043] According to another preferred embodiment of the present invention, the temperature of the mixture reaction mass is controlled by the addition of a solvent (water) to reduce the temperature increase gradient per minute of the reaction mass to less than 1°C / min.

[0044] According to yet another preferred embodiment of the present invention, the temperature of the mixture reaction mass is controlled by a second addition of solvent (water) to reduce the temperature rise gradient per minute of the reaction mass to less than 0.7°C / min.

[0045] Preferably, the temperature of the reaction mass is controlled by the third addition of solvent (water) to reduce the temperature ramp rate of the reaction mass to less than 0.3° C. / min.

[0046] Preferably, the temperature of the reaction mass is controlled by the fourth addition of solvent (water) to reduce the temperature ramp rate of the reaction mass to less than 0.1° C. / min.

[0047] According to a preferred embodiment of the present invention, the kappa number of the cellulose obtained is less than 10, preferably the kappa number of the cellulose obtained is less than 5.

[0048] According to a preferred embodiment of the present invention, -sulfuric acid; heterocyclic compounds; and -Peroxide A process for delignifying biomass using an aqueous acidic composition comprising:

[0049] According to yet another aspect of the present invention, there is provided a process for carrying out controlled exothermic delignification of biomass, the process comprising: - providing a container; - providing a biomass batch comprising lignin, hemicellulose, and cellulose fibers to the vessel; - providing a Modified Caro's Acid Composition selected from the group consisting of Composition A, Composition B, and Composition C, The composition A is sulfuric acid in an amount ranging from 20 to 70% by weight 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; peroxide, The composition B is - alkyl sulfonic acid, - containing a peroxide, wherein the acid is present in an amount ranging from 40 to 80% by weight of the total weight of the composition, and the peroxide is present in an amount ranging from 10 to 40% by weight of the total weight of the composition, The composition C is sulfuric acid, - a two-component modifier component, compounds containing an amine moiety, and -Compounds containing sulfonic acid moieties a two-component modifier component comprising: peroxides, including providing a modified Caro's acid composition; - exposing the biomass to the modified Caro's acid composition to form a reaction mass; - contacting the modified Caro's acid composition with the biomass for a period of time sufficient to cause a delignification reaction to occur and remove greater than 90% by weight of the lignin and hemicellulose from the biomass; the temperature of the delignification reaction, - adding water to said container; - adding biomass to said vessel; and -Use a heat exchanger and controlling the temperature to be below 55°C by a method selected from the group consisting of:

[0050] According to a preferred embodiment of the present invention, the temperature of the reaction mass is maintained at a temperature in the range of 30-45°C.

[0051] According to a preferred embodiment of the present invention, at least a portion of the resulting liquid fraction obtained at the end of the reaction is used to treat at least one additional batch of biomass.

[0052] According to a preferred embodiment of the present invention, at least a portion of the resulting liquid fraction obtained at the end of the reaction is used to treat at least four additional batches of biomass.

[0053] According to a preferred embodiment of the present invention, at least a portion of the resulting liquid fraction obtained at the end of the reaction is used to further treat additional biomass batches until the peroxide concentration in the resulting liquid reaches less than 1%.

[0054] In accordance with a preferred embodiment of the present invention, the aqueous acidic composition combines both a sulfuric acid component and a peroxide component and thus comprises a Modified Caro's Acid Composition selected from the group consisting of Composition A, Composition B, and Composition C; The composition A is sulfuric acid in an amount ranging from 20 to 70% by weight 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; peroxide, The composition B is - alkyl sulfonic acid, - containing a peroxide, wherein the acid is present in an amount ranging from 40 to 80% by weight of the total weight of the composition, and the peroxide is present in an amount ranging from 10 to 40% by weight of the total weight of the composition, The composition C is sulfuric acid, - a two-component modifier, compounds containing an amine moiety, and -Compounds containing sulfonic acid moieties a two-component modifier comprising: -peroxides,

[0055] According to a preferred embodiment of the invention, the sulfuric acid, the compound comprising an amine moiety and a sulfonic acid moiety, and the peroxide are present in a molar ratio of 1:1:1 or greater.

[0056] According to a preferred embodiment of the invention, the sulfuric acid, the compound comprising an amine moiety and a sulfonic acid moiety, and the peroxide are present in a molar ratio of 15:1:1 or less.

[0057] According to a preferred embodiment of the invention, the sulfuric acid and the compound comprising an amine moiety and a sulfonic acid moiety are present in a molar ratio of 3:1 or greater.

[0058] According to a preferred embodiment of the present invention, the compound comprising an amine moiety and a sulfonic acid moiety is selected from the group consisting of taurine; taurine derivatives; and taurine-related compounds.

[0059] According to a preferred embodiment of the present invention, the taurine derivative or taurine-related compound is selected from the group consisting of taurolidine, taurocholic acid, taurocelecholic acid, tauromustine, 5-taurinomethyluridine and 5-taurinomethyl-2-thiouridine, homotaurine (tramiprosate), acamprosate, and taurates and aminoalkylsulfonic acids, where alkyl is selected from the group consisting of C1-C5 linear alkyls and C1-C5 branched alkyls. Preferably, the linear alkylaminosulfonic acids are selected from the group consisting of methyl, ethyl (taurine), propyl, and butyl.

[0060] Preferably, the branched aminoalkyl sulfonic acid is selected from the group consisting of isopropyl; isobutyl; and isopentyl.

[0061] According to a preferred embodiment of the present invention, the compound comprising an amine moiety and a sulfonic acid moiety is taurine.

[0062] According to a preferred embodiment of the invention, the sulfuric acid and amine moieties and the compound containing the sulfonic acid moiety are present in a molar ratio of 3:1 or greater.

[0063] According to a preferred embodiment of the present invention, the compound comprising an amine moiety is an alkanolamine selected from the group consisting of monoethanolamine; diethanolamine; triethanolamine; and combinations thereof.

[0064] According to a preferred embodiment of the present invention, the compound containing a sulfonic acid moiety is selected from the group consisting of alkylsulfonic acids and combinations thereof.

[0065] According to a preferred embodiment of the present invention, the alkyl sulfonic acid is selected from the group consisting of alkyl sulfonic acids, wherein the alkyl group ranges from C1 to C6, and is linear or branched; and combinations thereof.

[0066] According to a preferred embodiment of the present invention, the alkyl sulfonic acid is selected from the group consisting of methanesulfonic acid; ethanesulfonic acid; propanesulfonic acid; 2-propanesulfonic acid; isobutylsulfonic acid; t-butylsulfonic acid; butanesulfonic acid; isopentylsulfonic acid; t-pentylsulfonic acid; pentanesulfonic acid; t-butylhexanesulfonic acid; and combinations thereof.

[0067] According to a preferred embodiment of the invention, the alkyl sulfonic acid and the peroxide are present in a molar ratio of 1:1 or greater.

[0068] According to a preferred embodiment of the present invention, the compound containing a sulfonic acid moiety is methanesulfonic acid.

[0069] According to a preferred embodiment of the invention, in composition C, the sulfuric acid, the compound comprising an amine moiety, and the compound comprising a sulfonic acid moiety are present in a molar ratio of 1:1:1 or greater.

[0070] According to a preferred embodiment of the present invention, in composition C, the sulfuric acid, the compound containing an amine moiety and the compound containing a sulfonic acid moiety are present in a molar ratio ranging from 28:1:1 to 2:1:1.

[0071] According to another preferred embodiment of the present invention, -sulfuric acid; -Heterocyclic compounds A process for delignifying biomass using an aqueous acidic composition comprising: Here, the sulfuric acid and the heterocyclic compound are present in a molar ratio of 1:1 or greater.

[0072] Preferably, sulfuric acid and the heterocyclic compound are present in a molar ratio ranging from 28:1 to 2:1. More preferably, sulfuric acid and the heterocyclic compound are present in a molar ratio ranging from 24:1 to 3:1. Preferably, sulfuric acid and the heterocyclic compound are present in a molar ratio ranging from 20:1 to 4:1. More preferably, sulfuric acid and the heterocyclic compound are present in a molar ratio ranging from 16:1 to 5:1. According to a preferred embodiment of the present invention, sulfuric acid and the heterocyclic compound are present in a molar ratio ranging from 12:1 to 6:1.

[0073] Also preferably, the heterocyclic compound has a molecular weight of less than 300 g / mol. Also preferably, the heterocyclic compound has a molecular weight of less than 150 g / mol. More preferably, the heterocyclic compound is a secondary amine. According to a preferred embodiment of the present invention, the heterocyclic compound is selected from the group consisting of imidazole; triazole; and N-methylimidazole.

[0074] According to one aspect of the present invention, -sulfuric acid; Heterocyclic compounds; and peroxide A process for delignifying biomass, such as wood, using an aqueous acidic composition comprising: Here, the sulfuric acid and the heterocyclic compound are present in a molar ratio ranging from 2:1 to 28:1.

[0075] Preferably, for modified Caro's acid with TEOA / MSA, the molar composition is as follows: H2O:H2O2:H2SO4:TEOA:MSA in a molar ratio of 56:10:10:1:1.

[0076] Preferably, according to an embodiment in which the addition of water to the vessel is avoided whenever possible, the delignification reaction is controlled by controlling the temperature of the mixture in the vessel and, therefore, the exothermic nature of the delignification. The reaction is controlled by slowly adding biomass to a vessel containing a sulfuric acid component and a peroxide component, allowing the reaction to occur before adding more biomass material. When the reaction of a first amount of biomass is substantially complete and more biomass material is added, this additional material reacts and begins delignification, but the reaction is regulated to some extent by the presence of the previously delignified material, and therefore, for subsequent biomass additions to the vessel, the reaction of a second amount of biomass in a more dilute mixture is carried out, and so on. According to a preferred embodiment of the present invention, the temperature increase resulting from the delignification reaction (which is exothermic) is utilized to heat the reaction mixture to the desired range of 30-45°C. This is consistent with an advanced temperature control system that allows for hourly heat generation.

[0077] According to one aspect of the present invention, there is provided a process for carrying out controlled exothermic delignification of biomass, the process comprising: - providing a container; - providing a biomass containing lignin, hemicellulose, and cellulose fibers in said vessel; - providing an aqueous acidic composition comprising a sulfuric acid component; - providing a modifier component; - providing a peroxide component; - exposing the biomass to the sulfuric acid component, the modifier component, and the peroxide component to form a reaction mass; - contacting the sulfuric acid component, the modifier component, and the peroxide component with the biomass for a period of time sufficient to cause a delignification reaction to occur and remove greater than 90% by weight of the lignin and hemicellulose from the biomass.

[0078] Features and advantages of the embodiments of the present application will become apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0079] [Figure 1] FIG. 1 illustrates a system in which the process according to a preferred embodiment of the present invention can be implemented. [Figure 2] FIG. 2 shows a scaled-up system in which a process according to a preferred embodiment of the present invention can be carried out. DETAILED DESCRIPTION OF THE INVENTION

[0080] According to a preferred embodiment of the present invention, there is provided a process for carrying out controlled exothermic delignification of biomass, the process comprising: - providing a system comprising at least a first container and a second container; - providing a biomass comprising lignin, hemicellulose and cellulose fibers to said first vessel; - providing an aqueous acidic composition comprising a sulfuric acid component; - providing a modifier component; - providing a peroxide component; - exposing the biomass to the sulfate and peroxide components to form a reaction mass; - mixing the reaction mass; - contacting the sulfuric acid component and the peroxide component with the biomass for a period of time sufficient to cause a delignification reaction to occur and remove a predetermined amount of the lignin from the biomass; contacting the sulfate and peroxide components with the biomass, wherein the predetermined amount is assessed by testing a first kappa number of the biomass with a suitable device, and when the first kappa number of the biomass is reached, the biomass is transferred to the second vessel; - increasing the temperature of the biomass mixture during the residence time of the biomass in the second vessel; - allowing the sulfuric acid component, modifier component, and peroxide component to continue the delignification reaction at the second temperature to remove a second predetermined amount of the lignin from the biomass; allowing the removal of a second predetermined amount of the lignin from the biomass, wherein the second predetermined amount is assessed by testing a second kappa number of the biomass using a suitable device, and the biomass is removed from the second vessel once the second kappa number of the biomass is reached; - optionally using a washing step to separate the liquid portion containing the lignin and hemicellulose from the solid portion containing the cellulose extracted from the biomass.

[0081] The above-described process may be accomplished using a system such as that shown in Figure 1. The system, according to a preferred embodiment of the present invention, comprises a first vessel (110) operating at a first temperature, to which the biomass (101) having a first kappa number is added and subsequently mixed with a delignification composition (102) for a predetermined period of time or until the biomass in the reaction mixture reaches a second predetermined kappa number, which is measured during the reaction using a kappa analyzer (115). Preferably, once the biomass in the reaction mixture reaches the second predetermined kappa number, the biomass / delignification composition is transferred to a second vessel (120) where the delignification reaction is carried out at a second temperature higher than the first temperature. The biomass in the reaction mixture having the second kappa number continues to be mixed with the delignification composition for a predetermined period of time or until the biomass in the reaction mixture reaches a third predetermined kappa number, which is measured during the reaction using a kappa analyzer (125) associated with the second vessel (120). Preferably, once the biomass in the reaction mixture reaches the third predetermined kappa number, the biomass / delignification composition is transferred to a third vessel where the delignification reaction occurs at a third temperature higher than the second temperature. The biomass in the reaction mixture having the third kappa number continues to be mixed with the delignification composition for a predetermined period of time or until the biomass reaches a fourth and final predetermined kappa number, which is measured during the reaction using a kappa analyzer (135) associated with the second vessel (130). Preferably, once the biomass in the reaction mixture reaches the fourth predetermined kappa number, the reaction mixture is then discharged, the solid portion is separated from the liquid portion, and the liquid is recovered and re-introduced into the process by injecting it into the first vessel. The cellulose containing solid portion is subjected to other post-delignification treatment steps depending on its end use.

[0082] The system includes a temperature indicator / controller (111) designed to monitor temperature setpoint changes and control the setpoint of the heat exchanger (112), the spray nozzle (117). The spray nozzle (117) on the central main piping system is designed to provide pumped mixing of the biomass and delignification composition (chemical liquor). According to a preferred embodiment, the solution is heated and cooled using an external heat exchanger (HE) with process fluid (chilled water or glycol). The liquid is extracted from the tank through a screen and enters the heat exchanger. According to a preferred embodiment, secondary heating / cooling is performed via the tank jacket.

[0083] According to a preferred embodiment of the invention, the system further comprises an extraction screen for the chemical liquid, designed to extract the chemical liquid from the container and pump it to the spray nozzle.

[0084] As seen in Figure 1, the system includes a heating / cooling jacket (118) designed to be a secondary temperature control method to cooling / heating. This can prove useful because the delignification reaction is exothermic and control of temperature is desirable to ensure yield is maximized.

[0085] Located at the bottom of each vessel (110, 120, 130) is an actuated discharge valve (116, 126 and 136, respectively) designed to discharge the product slurry (biomass and delignified composition) to the next stage.

[0086] Advanced process control (146) (APC) tools are typically used for individual processes and typically connect to a distributed control system (148) (DCS) that controls the entire process facility. APC is a developed system that integrates multiple factors, including the DCS. System components communicate virtually with each other and adjust parameters according to programmed inputs. It utilizes real-time optimization, reading process variables and continuously adjusting them to the target ranges for which they are programmed.

[0087] The system also includes a cooler and heater supply loop (119) designed to be the primary method for cooling / heating the solution to the desired parameters.

[0088] In the embodiment shown in Figure 1, the system further comprises a central main piping system, which is a piping system equipped with spray nozzles (117) designed to distribute the chemical solution to the biomass. The system further comprises kappa analyzers (115, 125, 135, respectively) at each stage to determine the pulping rate.

[0089] According to a preferred embodiment of the present invention, the system further comprises at least one tank baffle designed to enhance mixing efficiency. Each of the vessels (110, 120, 130) in the system further comprises a cone bottom (113, 123, 133, respectively), which is desirable for easier discharge of the reaction mixture from one vessel to the next.

[0090] According to a preferred embodiment of the present invention, the system further comprises top-mounted agitators (127, 137) designed to provide the desired agitation to the reaction mixture in the second vessel (120) and third vessel (130). In some cases, the mixing in the first vessel (110) may be achieved by a paddle mixer, and in other cases by recirculation of the reaction mixture through a pump and injection nozzle. In other cases, there may be a combination of paddle agitator-achieved mixing and pump recirculation.

[0091] According to a preferred embodiment of the present invention, the system further comprises top-mounted agitators (127, 137) designed to provide the desired agitation to the reaction mixture in the second vessel (120) and third vessel (130). Mixing in the first vessel (110) is achieved by recirculation of the reaction mixture through a pump and injection nozzle.

[0092] According to a preferred embodiment of the present invention, the process includes a blending step in which a liquid containing a unique blend is delivered to a reactor vessel. A mixer then agitates the blend within the reactor during chemical addition, biomass addition, and reaction. To increase mixing, a circulation pump is used to circulate material through a mesh to the top. Biomass is added to the reactor through the top inlet port.

[0093] The delignification reaction occurs, creating an exothermic environment within the reaction vessel. The level and temperature within the reactor are monitored. Once the first stage of the reaction is complete (based on the value obtained by analysis with the kappa analyzer), an actuation valve is opened and the reaction mixture is transferred to a second vessel for the second stage of the delignification process. This process is repeated for stages 2 and 3 (i.e., if a second and third vessel are present).

[0094] Preferably, the mixture is heated using a glycol-water mixture heated by a boiler. The heat exchanger fluid bypasses the condenser and travels through the reactor (vessel) heat exchanger and tank jacket to heat the reaction mixture to the desired reaction initiation temperature. During biomass addition and reaction, the glycol-water mixture is cooled by the condenser. The heat exchanger fluid travels through the outer reactor heat exchanger and cooling jacket to maintain the desired reaction temperature.

[0095] According to a preferred embodiment of the present invention, the system further comprises an emergency shutdown procedure in which if the reaction temperature rises above a certain set point, which may possibly be set at 50° C., a control valve opens and the reactor fills with water, thereby stopping the reaction. When such a shutdown occurs, the contents of the reactor are rerouted via a circulation pump to an overflow tank.

[0096] According to a preferred embodiment of the present invention, the system is configured so that the initial reaction temperature of the process is in the range of 20-30°C and increases as the reaction progresses. A temperature transmitter immersed in the reactor transmits this value to the temperature control system. When the temperature rises to 50°C, the temperature controller signals the control valve on the water outlet line to open 25%. According to a preferred embodiment of the present invention, for every 1°C increase recorded by the temperature transmitter starting at 50°C, the system signals the control valve to open an additional 25% until it is fully open at 53°C, completely stopping the reaction. Preferably, temperature control is carried out by using a jet nozzle spray that can evenly spray the surface of the chemical-biomass mixture. The sprayed water is then mixed with the mixture in the presence of an agitator or by recirculating the reaction mixture (i.e., without a conventional agitator).

[0097] As shown in Figure 2, a system according to a preferred embodiment of the present invention comprises a first vessel (210) operating at a first temperature, to which biomass (201) having a first kappa number is added and subsequently mixed with a delignification composition (202) for a predetermined period of time or until the biomass reaches a second predetermined kappa number, which is measured during the reaction using a kappa analyzer (215). Preferably, once the biomass reaches the second predetermined kappa number, the biomass / delignification composition is transferred to a second vessel (220) where the delignification reaction is carried out at a second temperature higher than the first temperature. The biomass having the second kappa number continues to be mixed with the delignification composition for a predetermined period of time or until the biomass reaches a third predetermined kappa number, which is measured during the reaction using a kappa analyzer (225) associated with the second vessel (220). Preferably, once the biomass reaches the third predetermined kappa number, the biomass / delignification composition is transferred to a third vessel, where the delignification reaction is carried out at a third temperature set higher than the second temperature. The biomass having the third kappa number continues to be mixed with the delignification composition for a predetermined period of time or until the biomass reaches a fourth and final predetermined kappa number, the kappa number being measured during the reaction using a kappa analyzer (235) associated with the second vessel (230). Preferably, once the biomass reaches the fourth predetermined kappa number, the reaction mixture is then discharged, the solid portion separated from the liquid portion, and the liquid recovered and re-injected into the process by injecting it into the first vessel. The mixer used in the first vessel (210) is a paddle agitator (217).

[0098] According to a preferred embodiment of the present invention, the biomass loading in the delignification vessel may be increased to 20 wt%. According to a preferred embodiment of the present invention, the biomass loading in the delignification vessel may be increased to 15 wt%. According to a preferred embodiment of the present invention, the biomass loading in the delignification vessel may be increased to 10 wt%. Preferably, the biomass loading in the delignification vessel may be increased to 8 wt%. More preferably, the biomass loading in the delignification vessel may be increased to 7 wt%. According to a preferred embodiment of the present invention, the biomass loading in the delignification vessel is in the range of 4 to 6 wt%.

[0099] According to a preferred embodiment of the present invention, the initial temperature in the vessel where delignification occurs is as low as 18-20°C, yet still provides significant delignification within a reasonable period of time. According to a preferred embodiment of the present invention, the initial temperature in the vessel where delignification occurs is 25°C. More preferably, the initial temperature in the vessel where delignification occurs is 30°C. According to another preferred embodiment of the present invention, the initial temperature in the vessel where delignification occurs is in the range of 30-45°C. According to yet another preferred embodiment of the present invention, the initial temperature in the vessel where delignification occurs is in the range of 32-40°C.

[0100] According to preferred embodiments of the present invention, the duration of the delignification reaction can last up to 24 hours. Preferably, the duration of the delignification reaction can last up to 12 hours. Preferably, the duration of the delignification reaction can last up to 6 hours. Preferably, the duration of the delignification reaction can last up to 4 hours. According to preferred embodiments of the present invention, the duration of the delignification reaction takes about 3 hours. In some preferred embodiments, the duration of the delignification reaction can be as little as 1.5 hours.

[0101] According to a preferred embodiment of the present invention, the chemicals used in the delignification reaction can be reused in subsequent delignifications and still maintain good delignification capacity. According to a preferred embodiment of the present invention, the chemicals used in the delignification reaction can be reused in subsequent delignifications by adding a portion of the peroxide component (called "topping up") and still maintain good delignification power. Recycling the chemicals used in delignification offers several advantages, one of the most obvious being the elimination of discharge of spent (or used) chemicals. According to a preferred embodiment of the present invention, the chemicals used in the delignification reaction can be reused several times by topping up with peroxide between each reaction.

[0102] According to a preferred embodiment of the present invention, a beneficial approach to optimizing hydrogen peroxide (HO) consumption is to recycle the reaction blend after each reaction and remove the solid cellulose by filtration. This is done and is highly advantageous, since in many observed cases only 20% of the hydrogen peroxide (HO) added to the biomass blend is consumed. Thus, by recycling the composition containing acid, modifier, and peroxide, which has a large amount of unreacted peroxide components after separation of the resulting cellulose, the overall consumption of peroxide (HO) is substantially reduced.

[0103] According to a preferred embodiment of the present invention, good control of reaction temperature is one of the factors driving the delignification reaction, demonstrating that the reaction is kinetically driven. Other experiments have demonstrated that delignification reaction times of 3 hours can be achieved. These experiments, conducted at temperatures ranging from 30 to 45°C, demonstrate that the desired delignification is achieved without affecting hydrogen peroxide (HO) consumption and the kappa number of the resulting cellulose.

[0104] According to a preferred embodiment of the present invention, the reaction temperature is within the range of 30-45°C, as this not only provides a consistent kappa number for the resulting cellulose, but also a consistent lignin-hemicellulose-depolymerized organic (LHDO) mixture. It also protects the LHDO from potential oxidation by hydrogen peroxide (HO). Preferably, the resulting LHDO is separated from the cellulose by filtration and purified from sulfuric acid. This provides a unique organic stream that can be easily upgraded to a high-value renewable fuel.

[0105] Large-scale experiment A series of delignification experiments using modified Caro's acid was conducted to evaluate the feasibility of recycling the modified Caro's acid composition for sequential batch processing. Sequential batch processing was also hypothesized to represent the potential for applying such technology to the continuous digestion (or delignification) of lignocellulosic biomass. The biomass used was hardwood with a kappa number of approximately 120.

[0106] Therefore, several batches of lignocellulosic biomass were delignified using modified Caro's acid with the following characteristics listed in Table 1. [Table 1]

[0107] The first batch of biomass was mixed with the modified Caro's acid described above, which was maintained for 20 hours at a temperature of 32-37° C. At the end of the reaction, the kappa number was measured using a kappa analyzer and was found to be 1.04.

[0108] The remaining liquid, containing the modified Caro's acid with reduced peroxide content, was mixed to treat a second batch of biomass. The resulting mixture was maintained at a temperature of 32-37°C for 20 hours. The kappa number at the end of the reaction was measured using a kappa analyzer and found to be 1.33.

[0109] The remaining liquid, containing modified Caro's acid with reduced peroxide content, was mixed to treat a third batch of biomass. The resulting mixture was maintained at a temperature ranging from 32 to 37°C for 20 hours. The kappa number at the end of the reaction was measured using a kappa analyzer and found to be 1.93.

[0110] The remaining liquid containing the modified Caro's acid with reduced peroxide content was mixed to treat a fourth batch of biomass. The resulting mixture was maintained at a temperature of 32-37°C for 20 hours. The kappa number at the end of the reaction was measured using a kappa analyzer and found to be 2.06.

[0111] The remaining liquid containing the modified Caro's acid with reduced peroxide content was mixed with the fifth batch of biomass. The resulting mixture was maintained at a temperature of 32-37°C for 20 hours. The kappa number at the end of the reaction was measured using a kappa analyzer and found to be 4.14.

[0112] The level of peroxide remaining after treatment of the fifth batch of biomass was measured and determined to be approximately greater than 2%.

[0113] It is estimated that the modified Caro's acid composition can be reused for at least another biomass delignification treatment.

[0114] Based on the batch experiments above, it was determined that a continuous batch procedure can be performed to optimize delignification efficiency and have residence times of biomass through various steps.

[0115] Although the foregoing invention has been described in some detail for purposes of clarity and understanding, those skilled in the art, once familiar with the present disclosure, will appreciate that various changes in form and detail can be made therein without departing from the true scope of the invention as set forth in the appended claims.

Claims

1. A process for carrying out controlled exothermic delignification of biomass at temperatures below 50°C.

2. 1. A process for carrying out controlled exothermic delignification of biomass, said process comprising: - providing a system comprising at least a first container and a second container; - providing the biomass comprising lignin, hemicellulose and cellulose fibers in the first vessel; - providing an aqueous acidic composition comprising a sulfuric acid component; - providing a modifier component; - providing a peroxide component; - exposing said biomass to said sulfuric acid, modifier and peroxide components to form a reaction mass; - mixing the reaction mass; - contacting the sulfuric acid, modifier and peroxide components with the biomass for a period of time sufficient for a delignification reaction to occur and remove a predetermined amount of the lignin from the biomass; the predetermined amount is assessed by testing the biomass for a first kappa number using a suitable device, and once the first kappa number of the biomass is reached, the biomass is transferred to the second vessel; - increasing the temperature of the biomass mixture during the residence time of the biomass in the second vessel; - allowing the sulfuric acid component and the peroxide component to continue the delignification reaction at the second temperature to remove a second predetermined amount of the lignin from the biomass; - the second predetermined amount is assessed by testing the biomass for a second kappa number using a suitable device, and once the second kappa number of the biomass is reached, the biomass is removed from the second vessel; - optionally using a washing step to separate the resulting liquid portion comprising said lignin and hemicellulose from the solid portion comprising said cellulose extracted from the biomass.

3. the system comprising a third vessel into which the biomass is sent after being removed from the second vessel; - increasing the temperature of the biomass mixture during the residence time of the biomass in the second vessel; - allowing the sulfuric acid, modifier, and peroxide components to continue the delignification reaction at the second temperature to remove a third predetermined amount of the lignin from the biomass; 3. The process of claim 2, wherein the third predetermined amount is assessed by testing the biomass for a third kappa number using a suitable device, and when the third kappa number of the biomass is reached, the biomass is removed from the third vessel.

4. 4. The process of claim 3, wherein the process requires temperature control in the first vessel, the second vessel, and the third vessel.

5. 5. The process of claim 4, wherein the temperature control comprises a heat exchanger, a jacketed vessel, and a baffle.

6. 6. The process of claim 4, wherein the primary temperature control is a heat exchanger, the secondary control is a jacketed tank, and the tertiary control is a baffle.

7. The process of any one of claims 1 to 6, wherein the system has an outlet that allows for the separation of solids from liquids.

8. The process of any one of claims 1 to 7, wherein the mixing in the first vessel is carried out by recirculation of the reaction mass.

9. The process of any one of claims 1 to 8, wherein the mixing in the second vessel is carried out by a paddle mixer.

10. The process of any one of claims 1 to 9, wherein the mixing in the third vessel is performed by a paddle mixer.

11. the sulfuric acid component is derived from a Modified Caro's Acid Composition selected from the group consisting of Composition A, Composition B, and Composition C; The composition A is sulfuric acid in an amount ranging from 20 to 70% by weight 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; - peroxide, The composition B is alkylsulfonic acids, - a peroxide, wherein the acid is present in an amount ranging from 40 to 80% by weight of the total weight of the composition, and the peroxide is present in an amount ranging from 10 to 40% by weight of the total weight of the composition; The composition C is sulfuric acid, - a two-component modifier component, - a compound containing an amine moiety, and - Compounds containing sulfonic acid moieties a two-component modifier component comprising: - peroxides, The process according to any one of claims 1 to 10.

12. 11. The process of any one of claims 1 to 10, wherein the temperature of the reaction mass is maintained at a temperature in the range of 30 to 45°C.

13. 13. The process of any one of claims 1 to 12, wherein at least a portion of the resulting liquid fraction obtained at the end of the reaction is used to treat at least one additional batch of biomass.

14. 13. The process of any one of claims 1 to 12, wherein at least a portion of the resulting liquid fraction obtained at the end of the reaction is used to treat at least four additional batches of biomass.

15. 13. The process of any one of claims 1 to 12, wherein at least a portion of the resulting liquid fraction obtained at the end of the reaction is used to further treat additional biomass batches until the peroxide concentration reaches less than 1%.

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