Active lignocellulosic carbon material

Abstract

Chemically active lignocellulosic carbon sorbent materials comprising a high surface area, a high microporosity, and low impurities, and methods of making the same are described. The described structures provide unexpected advantages compared to currently available materials.

Description

Cross-references to related applications

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 520,754, filed August 21, 2023, entitled “Low Impurity Lignocellulosic Carbon,” which is incorporated herein by reference in its entirety. Technical Field

[0002] In various aspects and embodiments, this disclosure relates to low-impurity active adsorbent materials and methods for preparing the same. Background Technology

[0003] Activated carbon is characterized by its large specific surface area, typically 500-2500 m². 2 / g. Activated carbon can be produced from a variety of raw materials, including, for example, lignocellulose such as wood, sawdust, wood flour, cotton lint, coconut shells, fruit pits and kernels (such as olive pits), nut shells, palm, vegetables such as rice husks or straw; peat; lignite and bituminous coal; bituminous pitch; polymers, including synthetic and natural polymers, or combinations thereof.

[0004] Carbon activation is typically achieved using either thermal or chemical activation processes. Thermal activation usually involves treatment with high temperatures and steam and / or oxidizing gases (e.g., CO2 or O2) to carbonize and erode the raw material and create pores. Chemical activation is more commonly performed using lignocellulose raw materials and activating agents such as acids, strong bases, or salts (e.g., phosphoric acid, nitric acid, hydrochloric acid, sulfuric acid, potassium hydroxide, sodium hydroxide, potassium carbonate, calcium chloride, zinc chloride). This is generally a lower-temperature, higher-yield process and typically results in activated carbon with a higher surface area than thermally activated carbon.

[0005] Two commercially available lignophosphophosphate activated carbons are Nuchar ® SA-20 and Nuchar ® The RGCs are all from Ingevity Corporation (North Charleston, South Carolina). These carbons are widely used in a variety of applications, including water treatment for removing strong flavor and odor compounds, and decolorization of food ingredients, beverages, chemicals, and pharmaceuticals. They have a very high Brunauer-Emmett-Teller (BET) surface area (>1300 m²). 2 The relatively large mesopore volume (>60%) and the saturation ( / g) are a huge benefit for these applications.

[0006] Thermally activated carbon is typically considered in applications that benefit from more microporous materials, such as odor control. Typical thermally activated coal and coconut charcoal have >60% micropores, but their BET surface area is lower (<1200 m²) compared to chemically activated charcoal. 2 / g.

[0007] U.S. Patents 6,060,424 and 6,043,183 (Westvaco Corp., NY) discuss the ability to control the microporosity and mesoporosity of phosphoric acid-activated charcoal for carbon double-layer capacitor applications. Specifically, U.S. Patent 6,060,424 discusses a micropore volume >75%, and U.S. Patent 6,043,183 discusses a mesopore volume >75%, both exhibiting high BET surface area.

[0008] Regardless of desired porosity, a clear consequence of phosphoric acid activation is that the product may contain a certain level of residual phosphorus. For example, Ingevity Nuchar... ® Norit and Ceca commercial high-surface-area activated carbons range from approximately 1,600 to 10,000 ppm of elemental phosphorus. These levels are not significant for their applications, but in some applications, residual phosphorus levels in activated carbon may be important and require reduction while still maintaining a high BET surface area. Specifically, understanding or minimizing phosphorus and other impurity levels in high-BET surface-area activated carbon can be important in water treatment to minimize eutrophication and in some electrochemical applications to reduce resistance, improve cycle stability, increase capacity, or extend electrode life. This is mentioned in U.S. Patent 11,688,855.

[0009] Therefore, there is a need in the field for activated carbon materials with high surface area, high microporosity or high medium porosity, which have relatively low production costs but low phosphorus and other impurity content. Summary of the Invention

[0010] This paper describes chemically activated carbon materials formed from lignocellulose carbon precursors and methods for their preparation. The activated lignocellulose carbon materials surprisingly and unexpectedly exhibit low levels of impurities, such as phosphorus (P), and at least one of high surface area, high microporosity, high to medium porosity, or combinations thereof. For applications requiring low residual P, the choice of phosphoric acid activated carbon is not obvious.

[0011] Therefore, in one aspect, this disclosure provides a chemically active lignocellulose carbon as described herein. In any aspect of the embodiments described herein, the chemically active lignocellulose carbon is mesoporous or microporous, having reduced impurities and a high surface area compared to untreated activated carbon.

[0012] In any aspect or embodiment described herein, the chemically active lignocellulose carbon has a nitrogen BET surface area of ​​at least 1200 m². 2 / g.

[0013] In any aspect or embodiment described herein, the chemically active lignocellulose carbon is activated by phosphoric acid.

[0014] In any aspect or embodiment described herein, lignocellulose carbon comprises wood.

[0015] In any aspect or embodiment described herein, the chemically active lignocellulose carbon comprises a micropore content of more than about 50% of the total pore volume.

[0016] In any aspect or embodiment described herein, the chemically active lignocellulose carbon comprises a micropore content of less than about 50% of the total pore volume.

[0017] In any aspect or embodiment described herein, the phosphorus content of the chemically active lignocellulose carbon is less than about 1000 ppm, 900 ppm, 800 ppm, 700 ppm, 600 ppm, 500 ppm, 400 ppm, 300 ppm, 200 ppm, 100 ppm or lower.

[0018] The foregoing general application areas are given by way of example only and are not intended to limit the scope of this disclosure and the appended claims. Those skilled in the art will understand additional objectives and advantages associated with the compositions, methods, and processes of the present invention from the claims, description, and examples provided herein. For example, various aspects and embodiments of the invention can be utilized in numerous combinations, all of which are clearly contemplated by this specification. These additional advantageous objectives and embodiments are explicitly included within the scope of the invention. Publications and other materials used herein to elucidate the background of the invention and to provide additional details on practice in particular cases are incorporated by reference. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and, together with this specification, serve to explain the principles of the invention. The drawings are for illustrative purposes only and should not be construed as limiting the invention. Further objects, features, and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate exemplary embodiments of the invention, wherein: Figure 1A general process flow for an example of the invention is shown. A lignocellulose precursor material (e.g., a lignocellulose precursor) is chemically activated with phosphoric acid according to conventional method (I). For example, the material is blended and heated at 450-700°C for 0.5-3 hours, washed with water, and dried to an acceptable moisture level. The product from (I) is then subjected to one or more secondary processing steps (II), including steam treatment, and optionally treatment with a nitrogen / steam blend (at 600-900°C with 0-100% steam), and optionally an acid washing step. Compared to the initial activated carbon from (I), the resulting chemically activated lignocellulose carbon has a desired microporosity or mesoporosity, surface area, and reduced impurities, such as phosphorus. Detailed Implementation

[0020] While various embodiments of this disclosure have been described herein, those skilled in the art will understand that such embodiments are provided by way of example only. Those skilled in the art will understand that various modifications and alterations, variations and equivalent substitutions, can be made to the embodiments described herein without departing from the scope of this disclosure. It should be understood that various alternatives to the embodiments described herein can be employed in practicing this disclosure, and modifications can be made to adapt particular structures or materials to the teachings of this disclosure. It should also be understood that each embodiment of this disclosure may optionally be combined with any one or more embodiments of other embodiments consistent with those described herein.

[0021] When elements are presented in list form (e.g., Markush group), it should be understood that each possible subgroup of the element is also exposed, and any one or more elements can be removed from the list or group.

[0022] It should also be understood that, unless expressly stated to the contrary, in any method described or claimed herein that includes more than one action or step, the order of the actions or steps of the method is not necessarily limited to the order in which the actions or steps of the method are narrated, but this disclosure covers embodiments in which the order is so limited.

[0023] It should be further understood that, in general, where an embodiment in the specification or claims is referred to as containing one or more features, this disclosure also covers embodiments that consist of or are substantially composed of such features.

[0024] It should also be understood that any embodiment of this disclosure, such as any embodiment found in the prior art, may be expressly excluded from the claims, regardless of whether the specific exclusion is stated in the specification.

[0025] This document includes headings for reference and to help locate certain sections. The headings are not intended to limit the scope of the embodiments and concepts described in the sections under those headings, and those embodiments and concepts may be applicable throughout other parts of the disclosure.

[0026] All patent and non-patent documents cited in this paper are incorporated herein by reference in their entirety, as if each patent or non-patent document were explicitly and individually incorporated herein by reference in its entirety.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] When a range of values ​​is provided, it should be understood that every intermediate value between the upper and lower limits of the range, as well as any other stated or intermediate values ​​within the range, is included in this invention. The upper and lower limits of these smaller ranges may be independently included in a smaller range and also covered within this invention, subject to any exact exclusion of any limit within the stated range. Where the stated range includes one or both of the limit values, the range excluding any one or both of those included limit values ​​is also included in this invention.

[0029] As used herein and in the appended claims, the articles “a” and “an” refer to one or more (i.e., at least one) grammatical objects of the article, unless the context clearly indicates otherwise. By way of example, “an element” means one or more elements.

[0030] As used herein, the term "exemplary" means "serving as an example, illustration, or description." Any embodiment or feature characterized as "exemplary" herein is not necessarily to be construed as being more preferred or advantageous than other embodiments or features.

[0031] As used herein in the specification and claims, the phrase “and / or” should be understood to mean “any one or both” of the elements so combined, i.e., the elements are combined in some cases and separate in others. Multiple elements listed with “and / or” should be interpreted in the same way, i.e., “one or more” of the elements so combined. Other elements may optionally be present, whether related to or unrelated to those specifically identified by the “and / or” clause. Thus, as a non-limiting example, when used in conjunction with open-ended language such as “comprising,” a reference to “A and / or B” may refer only to A (optionally including elements other than B) in one embodiment; only to B (optionally including elements other than A) in another embodiment; both A and B (optionally including other elements) in yet another embodiment; and so on.

[0032] As used herein in this specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” should be interpreted as inclusive, that is, including a plurality of elements or at least one element in a list of elements, but also including more than one element and optionally additional unlisted items. Only when explicitly indicating the opposite term, such as “only one of…” or “exact one of…” or when used in the claims, “consisting of…” will refer to including a plurality of elements or exactly one element in a list of elements. In general, when preceded by an exclusive term, such as “any one,” “one of…,” “only one of…,” or “exact one of…,” the term “or” as used herein should be interpreted only as indicating an exclusive alternative (i.e., “one or the other, but not both”).

[0033] In the claims and in the foregoing description, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “constituting,” etc., should be understood as open-ended, that is, meaning including but not limited to. Only the transitional phrases “constituting of” and “constituting substantially of” should be closed or semi-closed transitional phrases, respectively.

[0034] As used herein in the specification and claims, the phrase "at least one" relating to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the element list, but not necessarily including at least one element from every element specifically listed in the element list, and does not exclude any combination of elements in the element list. This definition also allows for the optional presence of elements, whether related to or unrelated to those specifically identified elements, in addition to those specifically identified in the element list referred to by the phrase "at least one". Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently "at least one of A and / or B") in one embodiment may refer to at least one, optionally including more than one A, without B (and optionally including elements other than B); in another embodiment, it may refer to at least one, optionally including more than one B, without A (and optionally including elements other than A); in yet another embodiment, it may refer to at least one, optionally including more than one A, and at least one, optionally including more than one B (and optionally including other elements); and so on.

[0035] It should also be understood that in some methods described herein that include more than one step or action, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions of the method are described, unless the context otherwise requires.

[0036] The terms “about” or “approximately” mean an acceptable error for a particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined. In some embodiments, the terms “about” or “approximately” mean within one standard deviation. In some embodiments, when a particular error margin (e.g., the standard deviation from the average given in a data chart or table) is not listed, the terms “about” or “approximately” mean that the range of listed values ​​and the range included by rounding to the values ​​will take significant figures into account. In some embodiments, the terms “about” or “approximately” mean within 10% or 5% of a specified value. Whenever the term “about” or “approximately” precedes the first value in a series of two or more numerical values ​​or a range of two or more numerical values, the term “about” or “approximately” applies to each value in the series of numerical values ​​or the range of numerical values.

[0037] Whenever the term “at least” or “greater than” precedes the first value in a series of two or more values, the term “at least” or “greater than” applies to each value in the series of values.

[0038] Whenever the term "not exceeding" or "less than" precedes the first value in a series of two or more values, the term "not exceeding" or "less than" applies to each value in the series of values.

[0039] The present description refers to activated carbon materials with high surface area, high microporosity, or high to medium porosity, formed from chemically activated, such as phosphoric acid-activated, lignocellulose carbon precursors. Compared to untreated or conventional activated carbon materials, these materials surprisingly and unexpectedly exhibit high surface area, high microporosity, or high to medium porosity, and reduced levels of impurities, such as phosphorus.

[0040] Generally, the larger the surface area of ​​activated carbon, the greater its adsorption capacity. For example, the usable surface area of ​​activated carbon depends on its pore volume. Because the surface area per unit volume decreases with increasing pore size, a large surface area is usually maximized by maximizing the number of pores with extremely small sizes and / or minimizing the number of pores with extremely large sizes. According to IUPAC (International Union of Pure and Applied Chemistry), this paper defines pore size as micropores (pore width < 2 nm), mesopores (pore width = 2–50 nm), and macropores (pore width > 50 nm, and nominally 50 nm–100 micrometers).

[0041] refer to Figure 1 On the one hand, this disclosure provides a method for preparing chemically active lignocellulose carbon with reduced impurities and high surface area, the method comprising the step of providing chemically activated carbon, for example as described in the Kirk Othmer Encyclopedia of Chemical Technology, 4th Edition (see...). Figure 1 (I) and description). For example, the materials are blended and heated at 450-700°C for 0.5-3 hours, washed with water and dried to an acceptable moisture level.

[0042] In an exemplary embodiment, for from Figure 1 (I) The activated carbon material undergoes one or more secondary treatments (see...). Figure 1 (II) and the description include contact with steam and optionally a nitrogen / steam blend (with, for example, 0-100% steam) at a temperature of 600-900°C, and optionally an acid washing step, for example with acids such as organic or inorganic acids, such as gluconic acid, lactic acid, acetic acid, citric acid, nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid, etc. and combinations thereof, to remove or reduce other impurities, such as ash, iron, potassium, sulfur, calcium, sodium, zinc, phosphorus, silicon, copper, cobalt, aluminum, magnesium, nickel, chromium, barium, selenium, etc. or combinations thereof. Compared with the initial activated carbon from (I), the resulting chemically activated lignocellulose carbon has the desired microporosity or mesoporosity, surface area, and reduced impurities, such as phosphorus.

[0043] In some embodiments, the steam concentration used for secondary treatment ranges from 0 to 100% at different points in the process, and the temperature is from about 600°C to about 900°C. Based on proton-excited X-ray emission (PIXE) spectroscopy analysis, these steps reduce the P level from about 800-8000 ppm to below about 800 ppm.

[0044] Natural lignocellulose carbon precursors (non-activated carbon) can be activated using chemical activators. These chemical activators can be any chemical activator known in the art or to those skilled in the art. In any aspect or embodiment described herein, the chemical activator is selected from acids, bases, or salts.

[0045] In any aspect or embodiment described herein, the chemical activator is at least one of the following: phosphoric acid, sulfuric acid, boric acid, nitric acid, oxyacid, steam, air, peroxide, alkali metal hydroxide, potassium hydroxide, sodium hydroxide, sodium bicarbonate, potassium bicarbonate, urea, metal chloride, calcium chloride, zinc chloride, ammonia, carbon dioxide, potassium carbonate, or combinations thereof.

[0046] In some embodiments, the chemical activator is applied to the lignocellulose precursor in varying proportions, which may affect the levels of microporosity and mesoporosity. In any aspect or embodiment described herein, the chemical activator is phosphoric acid. In any aspect or embodiment described herein, the chemical activator is a phosphoric acid solution with a concentration up to about 85%.

[0047] In any aspect or embodiment described herein, the active lignocellulose carbon comprises a lignocellulose carbon precursor. The lignocellulose carbon precursor can be produced from a variety of materials, including, for example, peat, wood, sawdust, wood flour, lint, nut shells or kernels, carbohydrates, kernels or seeds, sawdust, palm, vegetables such as rice husks or straw, natural polymers, coconut shells, or combinations thereof. In any aspect or embodiment described herein, the lignocellulose carbon precursor is wood.

[0048] Comparable activated carbons include NUCHAR® activated carbon (Ingevity South Carolina, LLC, SC, USA) (which is a chemically activated carbon derived from wood and activated with phosphoric acid), phosphate wood charcoal from CECA and NORIT, and the carbon described in Vishvik Inc. (the predecessor of Ingevity) patent US6,060,424.

[0049] In some embodiments, the amount of chemical activator is an effective amount, i.e., the amount that achieves the desired microporosity or mesoporosity, surface area, or a combination thereof, as described herein.

[0050] In any aspect or embodiment described herein, the method includes a final purification step comprising contact with nitrogen, CO2, O2 and / or vapor at a temperature of about 600 to 900°C.

[0051] In any aspect or embodiment described herein, the produced activated carbon has at least one of the following: greater than about 500 m 2 BET surface area / g, and micropore content (i.e., microporous carbon) based on a ratio of at most 2 nm total pore volume to at most 100 nm total pore volume greater than about 50%, or micropore content (i.e., mesoporous carbon) based on a ratio of at most 2 nm total pore volume to at most 100 nm total pore volume less than about 50%.

[0052] In any aspect or embodiment described herein, the chemically active lignocellulose carbon as described herein contains a phosphorus (P) content of less than about 800 ppm (e.g., less than 800 ppm, 750 ppm, 700 ppm, 650 ppm, 600 ppm, 550 ppm, 500 ppm, 450 ppm, 400 ppm or lower) as determined by PIXE. This may be combined with small amounts of other impurities such as ash and transition metals such as iron, depending on additional washing steps including the use of acids such as organic or inorganic acids (e.g., sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid) or organic acids (e.g., citric acid, gluconic acid, etc.).

[0053] In addition to HCl, the roles of alternative organic and inorganic acids were investigated. Some exemplary acids included gluconic acid, lactic acid, acetic acid, citric acid, and phosphoric acid. Pickling with these alternative acids reduced metallic impurities within a similar range to that of HCl and also showed a successful reduction in phosphorus in the final product.

[0054] In any aspect or embodiment described herein, the phosphoric acid-activated lignocellulose carbon as described herein contains phosphorus in a recalcitrant form, which may include less volatile inorganic phosphates (such as tricalcium phosphate (Ca3(PO4)2), hydroxyapatite (Ca5(PO4)3(OH))) and cationic salts (such as magnesium phosphate, aluminum phosphate, potassium phosphate, and sodium phosphate), more volatile inorganic phosphates (such as monosodium phosphate or disodium phosphate), covalently linked phosphorus (including organophosphorus compounds or organophosphates), bulk and surface phosphorus, non-reactive and reactive phosphorus, soluble and poorly soluble phosphorus compounds, or combinations thereof.

[0055] Surprisingly, following the heat treatment scheme described in this article, phosphorus reduction of less than 800 ppm is possible even when the acid used for metal reduction of activated carbon is phosphoric acid. The results are shown in Table I below.

[0056] Table 1. For example, X-ray emission through proton excitation ( PIXE The phosphorus content, BET surface area, and microporosity ratio of phosphoric acid-activated charcoal were determined by BJH analysis.

[0057] In any aspect or embodiment described herein, chemical activation comprises phosphoric acid activation, wherein the active lignocellulose carbon described herein contains less than about 1000 ppm, 900 ppm, 800 ppm, 700 ppm, 600 ppm, 500 ppm, 400 ppm, 300 ppm, 200 ppm, 100 ppm or less of P, as determined by proton-excited X-ray emission (PIXE) spectroscopy.

[0058] In any aspect or embodiment described herein, the phosphoric acid activated lignocellulose carbon as described herein contains a P content of up to about 80%, as determined by PIXE for comparative carbon (see Table I).

[0059] In any aspect or embodiment described herein, as determined by PIXE, chemically activated (e.g., phosphoric acid activated) lignocellulose carbon as described herein contains reduced impurities, such as phosphorus, compared to initial (i.e., no secondary treatment) chemically activated carbon. In any aspect or embodiment described herein, as determined by PIXE, the phosphorus content (i.e., "P content") contained in the chemically activated (e.g., phosphoric acid activated) lignocellulose carbon as described herein is less than about 1000 ppm, less than about 900 ppm, less than about 800 ppm, less than about 700 ppm, less than about 600 ppm, less than about 500 ppm, less than about 450 ppm, less than about 400 ppm, less than about 350 ppm, less than about 300 ppm, less than about 250 ppm, less than about 200 ppm, or about 150 to about 500 ppm, or about 200 to about 500 ppm, or about 225 to about 500 ppm, or about 250 to about 500 ppm, or about 200 to about 450 ppm, or about 200 to about 400 ppm, or about 225 to about 400 ppm.

[0060] In any aspect or embodiment described herein, as determined by BJH analysis, the microporosity ratio (micropore volume / total pore volume up to 100 nm) of the phosphoric acid-activated lignocellulose carbon described herein is greater than 50%, 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95% or higher.

[0061] In any aspect or embodiment described herein, as determined by BJH analysis, the microporosity ratio (micropore volume / total pore volume up to 100 nm) of the phosphoric acid-activated lignocellulose carbon described herein is less than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5% or lower.

[0062] In any aspect or embodiment described herein, the chemically activated (e.g., phosphoric acid activated) lignocellulose carbon as described herein contains about 600 to about 3500 m³ 2 / g, approximately 800 to approximately 3000 m 2 / g or approximately 1000 to approximately 2500 m 2 The nitrogen BET content is approximately 150 to 800 ppm, or approximately 200 to 800 ppm, or approximately 225 to 800 ppm, or approximately 250 to 800 ppm, or approximately 200 to 500 ppm, or approximately 200 to 550 ppm, or approximately 225 to 600 ppm, as determined by PIXE, and the microporosity ratio (based on total pore volume) is 5%, 10%, 15%, 20%, 25%, 35%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or higher, as determined by BJH analysis. In some embodiments, the microporosity ratio is approximately 20% to less than 50%. In some embodiments, the microporosity ratio is greater than 50% to approximately 95%.

[0063] In any aspect or embodiment described herein, the chemically activated (e.g., phosphoric acid activated) lignocellulose carbon described herein comprises a nitrogen BET surface area of ​​at least 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, or 200. 0, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, ​​300 0, 3050, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3800, 3850, 3900, 3950, 4000 m 2Or larger, including all values ​​and ranges in between. In any aspect or embodiment described herein, the nitrogen BET surface area of ​​the active lignocellulose adsorbent material is from about 600 to about 3500 m². 2 / g, approximately 800 to approximately 3000 m 2 / g or approximately 1000 to approximately 2500 m 2 / g.

[0064] The activated carbon described herein is suitable for a variety of applications, including those that require or need low levels of residual impurities, such as low residual phosphorus (P). Those skilled in the art will readily appreciate that chemically activated lignocellulosic activated carbon produced with phosphoric acid is suitable for low-P applications, which is surprising and unexpected.

[0065] The low-impurity, high-surface-area, high-microporous and mesoporous chemically active lignocellulose carbon described herein is not limited to any application. Non-limiting examples of applications of the structures disclosed herein include catalysis, filtration, antimicrobial, antifungal, photovoltaic, antifungal, chemisorption, antiviral, textiles, ceramics, biotechnology, biomedicine, fuel cell systems, semiconductors, microelectronics, optics, gas storage applications, and energy storage applications.

[0066] Example The following examples are used to illustrate exemplary embodiments of the invention compared to currently available materials, and do not limit the scope of this disclosure.

[0067] Comparative Examples 1 and 2 are commercially available mesoporous phosphoric acid-activated lignocellulose carbons prepared by Ingenvit and sold under the trade name Nuchar. Comparative Example 3 is a prior art phosphoric acid-activated microporous lignocellulose carbon as described in U.S. Patent 6,060,424. Comparative Example 4 is a mesoporous phosphoric acid-activated lignocellulose carbon sold under the trade name ENO (prepared by CECA Specialty Chemicals), and Comparative Example 5 is a mesoporous phosphoric acid-activated lignocellulose carbon sold by Norit Activated Carbons under the trade name CA. PIXE analysis showed that the phosphorus levels of all five carbons exceeded 800 ppm.

[0068] Further steps in Example 1 of the present invention include using up to 100% steam at a temperature of up to about 760°C for a total of up to about 11.5 hours, and an HCl pickling step.

[0069] Additional steps in Example 2 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 4.5 hours, and an HCl pickling step.

[0070] An additional step in Example 3 of the present invention includes using up to 100% steam at a temperature of up to about 650°C for a total of up to about 15 hours.

[0071] Additional steps in Example 4 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 11 hours, and an HCl pickling step.

[0072] Further steps in Example 5 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 4.2 hours, and an H3PO4 pickling step.

[0073] Additional steps in Example 6 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 22 hours, and an HCl pickling step.

[0074] Further steps in Example 7 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 20.75 hours, and a gluconic acid washing step.

[0075] Further steps in Example 8 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 20.75 hours, and a lactic acid washing step.

[0076] Further steps of Example 9 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 20.75 hours, and a citric acid washing step.

[0077] Further steps in Example 10 of the present invention include using up to 100% steam at a temperature of up to about 850°C for a total of up to about 20.75 hours, and an acetic acid washing step.

[0078] Exemplary low-impurity, high-surface-area, high-medium-porosity, and microporous activated carbon materials as described herein are provided in Table I and compared with certain commercially available phospholipid cellulose activated carbon materials and prior art phospholipid cellulose activated carbon materials. The phosphorus content, BET surface area, and microporosity ratio of the phosphoric acid-activated charcoal were determined by proton-excited X-ray emission (PIXE) and obtained by BJH analysis.

[0079] Exemplary method.

[0080] Proton-excited X-ray emission (PIXE) spectroscopy PIXE is an exemplary technique for determining the elemental composition of a material or sample. PIXE measures X-rays emitted by a sample due to bombardment with high-energy ions. Several excitation beams produce X-rays with characteristic energies of the target element. Photon excitation (via X-rays) produces X-ray fluorescence spectra. Electron excitation in a scanning electron microscope or electron microprobe provides X-ray spectra with energy dispersion or wavelength dispersion (depending on the X-ray dispersion and detection method). 2+ or H + A beam of charged particles produces a PIXE spectrum. In all three cases, the excitation beam removes the core electron, and X-rays are emitted at specific energies as outer electrons change state to fill inner vacancies. The emitted X-ray energy is independent of the excitation process but is a property of the existing element. See, for example, Ishii, K. PIXE and Its Applications to Elemental Analysis. Quantum Beam Science (…). Quantum Beam Science )》. 3(2):1-14 (2019).

[0081] As an analytical technique, PIXE has several advantages. It is non-destructive and provides signal levels similar to its electron beam counterpart, but with a better signal-to-background ratio. The background in electron spectroscopy originates from bremsstrahlung, which is largely non-existent because even at PIXE energies, He... 2+ or H + Ions also move much slower than electrons. Another advantage of PIXE over electron-excited spectroscopy is that it studies insulating samples.

[0082] BET surface area Surface area was measured by nitrogen physisorption in Micromeritics ASAP 2420 (Nockros, Georgia) using the Bruno-Emmett-Taylor (BET) method, according to ISO 9277:2010. Sample preparation procedures involved degassing at 250°C for at least two hours, typically achieving a stable <2 μm Hg vacuum with sample separation. Record nitrogen adsorption isotherms for a 0.1 g sample at 77 K, targeting the following pressures: 0.04, 0.05, 0.085, 0.125, 0.15, 0.18, 0.2, 0.355, 0.5, 0.63, 0.77, 0.9, 0.95, 0.995, 0.95, 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.12, 0.1, 0.07, 0.05, 0.03, 0.01. Record actual points within a 5 mmHg or 5% absolute or relative pressure tolerance, whichever is more stringent. The time between consecutive pressure readings during equilibrium is 10 seconds. The non-ideality factor is 0.0000620. The density conversion factor is 0.0015468. The diameter of the heat-escaped hard sphere is 3.860 Å. The molecular cross-sectional area is 0.162 nm. 2 Data from the nitrogen adsorption isotherm within the relevant pressure range of 0.05 to 0.20 were used to apply the BET model.

[0083] Determine the orifice volume The pore volume (PV) of pores <1.8 nm to 100 nm was measured using nitrogen adsorption porosity obtained by the nitrogen adsorption method ISO 15901-2:2006 with Micromeritics ASAP 2420 (Norcross, Georgia). The sample preparation procedure for the nitrogen adsorption test involved degassing at 250 °C for at least two hours, typically achieving a stable <2 μm Hg vacuum with the sample separated. The pore volume of pores <1.8 nm to 100 nm was determined from the desorption branch of the 77 K isotherm of a 0.1 g sample. Nitrogen adsorption isotherm data were analyzed using the Kelvin and Halsey equations to determine the pore volume distribution for cylindrical pores according to the Barrett, Joyner, and Halenda (“BJH”) model. The non-ideal factor was 0.0000620. The density conversion factor was 0.0015468. The diameter of the heat-escaped hard sphere is 3.860 Å. The molecular cross-sectional area is 0.162 nm². The condensate thickness (Å) used for calculation related to the pore size (D, Å) is 0.4977 [ln(D)]² - 0.6981ln(D) + 2.5074. The target relative pressures for the isotherms are as follows: 0.04, 0.05, 0.085, 0.125, 0.15, 0.18, 0.2, 0.355, 0.5, 0.63, 0.77, 0.9, 0.95, 0.995, 0.95, 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.12, 0.1, 0.07, 0.05, 0.03, 0.01. Actual pressures are recorded within a tolerance range of 5 mmHg or 5% of the absolute or relative pressure, whichever is more stringent. The time between consecutive pressure readings during equilibrium is 10 seconds.

Claims

1. An active lignocellulose carbon material comprising chemically active lignocellulose carbon, wherein the chemically active lignocellulose carbon is treated with at least one of acid washing, heat treatment, or a combination thereof, thereby having a reduced level of impurities compared to untreated activated carbon.

2. The active lignocellulose carbon material according to claim 1, wherein the impurities comprise at least one of the following: ash, iron, potassium, sulfur, calcium, sodium, zinc, phosphorus, silicon, copper, cobalt, aluminum, magnesium, nickel, chromium, barium, selenium, or a combination thereof.

3. The activated lignocellulose carbon material according to claim 1 or 2, wherein the chemically activated lignocellulose carbon has a reduced phosphorus content compared to untreated activated carbon.

4. The active lignocellulose carbon material according to any one of claims 1 to 3, wherein the phosphorus content of the chemically active lignocellulose carbon is less than about 800 ppm.

5. The active lignocellulose carbon material according to any one of claims 1 to 4, wherein the ratio of the micropore volume to the total pore volume of the chemically active lignocellulose carbon is at least 50%.

6. The activated lignocellulose carbon according to any one of claims 1 to 5, wherein the ratio of the micropore volume to the total pore volume of the chemically activated lignocellulose carbon is less than 50%.

7. The activated lignocellulose carbon according to any one of claims 1 to 6, wherein the BET surface of the chemically activated lignocellulose carbon is at least 1200 μm. 2 / g.

8. The activated lignocellulosic carbon according to any one of claims 1 to 7, wherein the BET surface of the chemically activated lignocellulosic carbon is at least 1300 μm. 2 / g.

9. The activated lignocellulose carbon according to any one of claims 1 to 8, wherein the chemically activated lignocellulose carbon is activated by phosphoric acid.

10. The active lignocellulose carbon according to any one of claims 1 to 9, wherein the lignocellulose carbon comprises at least one of the following: peat, wood, sawdust, wood flour, lint, nut shells or kernels, carbohydrates, kernels or nut kernels, sawdust, palm, vegetables such as rice husks or straw, natural polymers, coconut shells or combinations thereof.

11. The active lignocellulose carbon according to any one of claims 1 to 10, wherein the lignocellulose carbon comprises wood or sawdust or both.

12. The activated lignocellulose carbon according to any one of claims 5 to 11, wherein the chemically activated lignocellulose carbon comprises a micropore volume based on a total pore volume greater than 60%.

13. An active lignocellulose carbon material comprising chemically active lignocellulose carbon, wherein the chemically active lignocellulose carbon has less than about 800 ppm of phosphorus.

14. The activated lignocellulosic carbon material according to claim 13, wherein the chemically activated lignocellulosic carbon is treated with at least one of acid washing, heat treatment, or a combination thereof, thereby having a reduced level of impurities compared to untreated activated carbon.

15. The activated lignocellulose carbon material according to claim 13 or 14, wherein the impurity, compared to untreated activated carbon, is at least one of the following: ash, iron, potassium, sulfur, calcium, sodium, zinc, silicon, copper, cobalt, aluminum, magnesium, nickel, chromium, barium, selenium, or a combination thereof.

16. The active lignocellulose carbon material according to any one of claims 13 to 15, wherein the ratio of the micropore volume to the total pore volume of the chemically active lignocellulose carbon is at least 50%.

17. The active lignocellulose carbon material according to any one of claims 13 to 16, wherein the BET surface of the chemically active lignocellulose carbon is at least 1200 μm. 2 / g.

18. The active lignocellulose carbon material according to any one of claims 13 to 17, wherein the BET surface of the chemically active lignocellulose carbon is at least 1300 μm. 2 / g.

19. The active lignocellulose carbon material according to any one of claims 13 to 18, wherein the chemically active lignocellulose carbon is activated by phosphoric acid.

20. The active lignocellulosic carbon material according to any one of claims 13 to 19, wherein the lignocellulosic carbon comprises at least one of the following: peat, wood, sawdust, wood flour, lint, nut shells or kernels, carbohydrates, kernels or nut kernels, sawdust, palm, vegetables such as rice husks or straw, natural polymers, coconut shells or combinations thereof.

21. The active lignocellulosic carbon material according to any one of claims 13 to 20, wherein the lignocellulosic carbon comprises wood or sawdust or both.

22. The active lignocellulose carbon material according to any one of claims 13 to 21, wherein the ratio of the micropore volume to the total pore volume of the chemically active lignocellulose carbon is less than about 50%.

23. The activated lignocellulose carbon according to any one of claims 13 to 22, wherein the chemically activated lignocellulose carbon comprises a micropore volume based on a total pore volume greater than 60%.

24. A chemically active lignocellulose carbon material comprising chemically active lignocellulose carbon, said chemically active lignocellulose carbon having at least one of the following: at least 500 μm 2 / g Brunauer-Emmet-Teller (BET) surface area, a ratio of at least 50% micropore volume to total pore volume, a ratio of less than 50% micropore volume to total pore volume, or a combination thereof, wherein the chemically active lignocellulose carbon is acid-washed or heat-treated, thereby having a reduced level of impurities compared to untreated activated carbon.

25. The activated lignocellulose carbon material according to claim 24, wherein the impurities, compared to untreated activated carbon, are at least one of the following: ash, iron, potassium, phosphorus, sulfur, calcium, sodium, zinc, silicon, copper, cobalt, aluminum, magnesium, nickel, chromium, barium, selenium, or a combination thereof.

26. The chemically active lignocellulose carbon material according to claim 24 or 25, wherein the phosphorus content of the chemically active lignocellulose carbon is less than about 500 ppm.

27. The chemically active lignocellulose carbon material according to any one of claims 24 to 26, wherein the BET surface area of ​​the chemically active lignocellulose carbon is at least 1300 m². 2 / g.

28. The chemically active lignocellulose carbon material according to any one of claims 24 to 27, wherein the chemically active lignocellulose carbon comprises a micropore volume based on a total pore volume greater than 60%.

Images