Extrudable formulation and method of making an extruded mesoporous alumina composite

Abstract

A method of making an extruded mesoporous alumina composite includes extruding a precursor paste comprising a gamma alumina powder, a boehmite powder, a porous inorganic filler, a pore forming agent, and a liquid carrier to form a green extrudate. The green extrudate is dried to remove the liquid carrier, such that a dried extrudate is formed. The dried extrudate is heated to a calcination temperature, whereby the pore forming agent is removed and the boehmite powder transforms to gamma alumina particles. Thus, a mesoporous alumina composite having the form of a consolidated extrudate is produced. The consolidated extrudate may be impregnated with a polyamine to form amine functional groups on an exposed surface thereof, rendering the extruded mesoporous alumina composite suitable for CO2 capture.

Description

PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066EXTRUDABLE FORMULATION AND METHOD OF MAKING AN EXTRUDED MESOPOROUS ALUMINA COMPOSITEFIELD OF THE DISCLOSURE

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 695587 filed September 17, 2024, the content of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates generally to materials suitable for adsorption-based CO2 capture and more particularly to a method of making an extruded mesoporous alumina composite.BACKGROUND

[0003] The increasing level of carbon dioxide (CO2) emission is considered one of the major environmental challenges that our planet is facing today. Since the onset of the Industrial Revolution in the 18thcentury, the atmospheric concentration of CO2 increased from about 280 ppm to 417 ppm in 2022. The record-high level of atmospheric CO2 concentration is the impetus for climate change and a sea level rise of 1-3 mm per year. If no action is taken, the atmospheric CO2 concentration is estimated to rise to 450 ppm by 2050. Because of surging public concerns about potential environmental damage, carbon capture and storage / sequestration (CCS) or utilization (CCU) have become key research topics in the twenty-first century. CCS aims at geological storage of CO2 in the deep underground, whereas CCU is a concept in which captured CO2 is utilized as a carbon source for chemical feedstocks, such as fuels and fine chemicals. The scientific community and industry are gradually concluding that CCS has economic limitations. Hence, industries are shifting toward exploration of CCU technologies.

[0004] Among carbon capture technologies, there is a growing interest in adsorption-based CO2 capture due to its combined potential of reduced energy penalty and easy retrofitting with minimal integration into existing industrial plants. The lower energy penalty is due to the lower specific heat capacity of solid sorbents in addition to avoiding evaporation of aPCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 large amount of water in the regeneration as compared to solvent-based technologies. More importantly, adsorption-based technology can offer the flexibility of capturing CO2 from different industrial CO2 sources due to its different sorbent regeneration modes (temperature / pressure swings) and reactor types.

[0005] In addition to carbon dioxide, sorbents selective to additional and / or other gaseos compounds can enable sorbent-based capture technologies to be used for a capturing one or more other selected compounds, such as other greenhouse gases.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The embodiments may be beter understood with reference to the following drawings and description. The components in the figures are not necessarily to scale.

[0007] FIG. 1 shows exemplary steps in a method to make an extruded mesoporous alumina composite that may in some examples have a honeycomb geometry.

[0008] FIG. 2 shows exemplary steps in a method to prepare an extrudable formulation suitable for fabricating the mesoporous alumina composite.

[0009] FIGS. 3A and 3B show scanning electron microscope (SEM) images of an exemplary extruded mesoporous alumina composite at two different magnifications (150X and 500X, respectively).

[0010] FIG. 4 shows the pore size distribution for the extruded mesoporous alumina composite of FIGS. 3A and 3B.

[0011] FIG. 5 shows the pore size distribution for another exemplary extruded mesoporous alumina composite.DETAILED DESCRIPTION

[0012] Described in this disclosure is a method of making an extruded mesoporous alumina composite as well as an extrudable formulation suitable for preparing the mesoporous alumina composite. In this disclosure, “mesoporous” may be used in reference to porous materials or structures having pore sizes in a range from 2 nm to 50 nm.

[0013] It has been recognized that surface modification of mesoporous materials with amine functional groups may improve CO2 capture. The extruded mesoporous aluminaPCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 composites described in this disclosure have large surface areas and pore volumes that can facilitate impregnation with large amounts of amine species, making them ideal for CO2 capture applications. In some examples, the extruded mesoporous aluminum composites may have a honeycomb geometry including a plurality of open channels extending longitudinally therethrough, as discussed further below. A challenging aspect of carbon capture processes is the substantial volume of gas that may contact the active sorbent, particularly in the case of direct air capture (DAC) processes, because of the extremely low CO2 concentration in air. Advantageously, the honeycomb geometry of the extruded mesoporous alumina composite may provide a gas-solid contactor with a low pressure drop and high surface area in which to perform the CO2 adsorption.

[0014] Fabrication of the mesoporous alumina composites entails extrusion of a precursor paste including gamma (y) alumina powder, boehmite powder, a porous inorganic filler, a pore forming agent (preferably at least two), and a liquid carrier. The constituents of the precursor paste and their functions, as well as preparation of the extrudable formulation, are discussed in detail below. First, the method of fabricating the extruded mesoporous alumina composites is described in reference to the flow chart of FIG. 1.

[0015] Referring to FIG. 1, the fabrication method includes extruding 102 a precursor paste comprising gamma alumina powder, boehmite powder, a porous inorganic filler, a pore forming agent, a liquid carrier, and optionally an extrusion aid to form a green extrudate. During extrusion, the precursor paste may be forced through a die having a geometry determined by the intended extruded product. For example, to produce a honeycomb geometry, the die may include inlets (for the precursor paste) on an inlet side of the die in fluid communication with outlets (for the green extrudate) on an outlet side of the die, where the outlets are shaped to extrude honeycomb cell walls from the constituents of the precursor paste. Upon extrusion, the honeycomb geometry may comprise an array of intersecting cell walls arranged in a repeating patern of cells that define longitudinally-extending open channels, which may serve as passageways for fluid flow (e.g. gas flow) in the final mesoporous alumina composite. To produce extruded composites having other desired shapes, e.g., pellets, rods, etc., the outlets of the die may have another suitable geometry. APCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 hydraulic or screw-driven ram may be employed for extrusion. As discussed below, the precursor paste is engineered to have flow properties suitable for extrusion.

[0016] After extrusion, the green extrudate may be dried 104 to remove the liquid carrier and form a dried extrudate. For example, the green extrudate may undergo passive drying at ambient temperature (22-25°C), or active drying at an elevated temperature (e.g., 100-140°C) and / or in a vacuum environment, whereby the liquid carrier (e.g., water, organic solvent) evaporates and a dried extrudate is obtained. Drying may take place for a time duration ranging from 30 minutes to 24 hours.

[0017] Referring again to FIG. 1, the dried extrudate may be heated 106 to a calcination temperature sufficient to convert the boehmite powder to gamma alumina powder and to pyrolyze (decompose) the pore forming agent. This in turn leads to the creation of pores as the pore forming agent is removed, as well as shrinkage and consolidation of the extruded alumina composite as boehmite converts to alumina, as discussed below. In some examples, the removal of the liquid carrier (or drying step) may occur as the extrudate is heated to the calcination temperature instead of in a separate drying step. Calcination may be carried out in air or optionally in a controlled atmosphere comprising an inert gas, such as nitrogen, argon, helium, etc. The calcination temperature may be least 550°C, or at least 650°C, and / or as high as 750°C, or as high as 850°C. Preferably, the calcination temperature is below the temperature at which gamma alumina may transform to alpha (a) alumina. The heating at the calcination temperature may occur for a time duration from 30 minutes to 24 hours. For example, the time duration may be 1-3 hours. The result is an extruded mesoporous alumina composite in the form of a consolidated extrudate, which includes gamma alumina, the porous inorganic filler (or a chemically modified version of the porous inorganic filler due to the effects of calcination), and a population of pores created by the removal of the pore forming agent. The term “composite” is used since the gamma alumina is not the only inorganic component that remains after calcination.

[0018] After fabrication, the consolidated extrudate may be impregnated with a polyamine to form amine functional groups on external surfaces of the extruded mesoporous alumina composite. The impregnation may entail dissolving a polyamine in a solvent (water or an organic solvent) to form an impregnation solution and exposing the consolidated extrudate toPCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 the impregnation solution (e.g., by immersion or coating). Upon drying to remove the solvent, the polyamine remains and amine functional groups are thereby incorporated onto exposed surfaces of the extruded mesoporous alumina composite. Surface-modified mesoporous alumina composites prepared as described above may provide excellent CO2 uptake capacity, fast adsorption kinetics and easy regeneration with stable cycling performance.

[0019] Preparation of the precursor paste used for the extrusion may be carried out according to the procedure shown in the flow chart of FIG. 2. A dry mixture may be formed by mixing together 202 the gamma alumina powder, the boehmite powder, the porous inorganic filler, and optionally the extrusion aid, and a liquid mixture comprising the pore forming agent may be prepared 204 as discussed below. The liquid mixture may be combined with the dry mixture and compounded 206 to form an extrudable precursor paste. It is also contemplated that the components of the dry mixture may be individually mixed into the liquid mixture to form the precursor paste. The compounding refers to mixing or blending to obtain a homogeneous plasticized paste. Advantageously, the precursor paste may have a plasticity or rheology which facilitates extrusion but also allow the paste to retain its shape after extrusion. In some examples, the precursor paste may be viscoelastic or have a strainrate dependent viscosity. For example, the precursor paste may have a reduced viscosity at high shear rates (e.g., while undergoing extrusion) and an increased viscosity at low shear rates (e.g., after extrusion, to maintain its shape), and thus may be described as shearthinning.

[0020] The gamma alumina powder comprises aluminum oxide (AI2O3) particles. The “gamma” indicates the crystallographic phase (y) of the AI2O3. Gamma alumina (y-AhOs) has a porous microstructure and a high specific surface area, and is known for its high hardness. The gamma alumina powder may have a nanoscale particle size. The boehmite powder comprises aluminum oxide hydroxide or y-AlO(OH) particles; thus, boehmite may be described as hydrated alumina. When exposed to temperatures in a range from 550-850°C, as occurs during calcination, boehmite transforms to gamma alumina. During this transformation, the hydrogen bonding inherent to boehmite is replaced by the stronger covalent bonding of gamma alumina, and also shrinkage occurs due to the water loss.PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066Accordingly, boehmite may play an important role as a binder and consolidation aid during calcination of the extruded mesoporous alumina composite. Due to the mesoporous structure of the gamma alumina and the increase in covalent bonding upon conversion from boehmite to gamma alumina, the consolidation that occurs during calcination may lead to improved mechanical integrity of the extruded body without sacrificing mesoporosity.

[0021] The porous inorganic filler may comprise a particulate clay mineral and / or volcanic ash that has a porous structure, preferably a mesoporous structure. For example, the porous inorganic filler may include sepiolite and / or pumice powder, both of which are lightweight, highly porous materials. The chemical composition of pumice may include silicon dioxide, aluminum silicate, aluminum oxide, and / or other oxides. Sepiolite is a hydrous magnesium silicate having a chemical formula Mg4Si6Ois(OH)2'6H2O. In particular, sepiolite is a highly porous, high surface area material that has a pore size distribution that is predominately in the mesopore size range (e.g., typically having a median pore size in the range of 2-5 nm). In addition to contributing to the mesoporosity and high porosity of the final extruded mesoporous alumina composite, the porous inorganic filler may be beneficial for improving the extrudability of the formulation. In particular, the inventor discovered that the addition of the porous inorganic filler may help to counter the liquid consistency of the pore forming agent(s) and ensure that the precursor formulation has the rheology of an extrudable paste.

[0022] The pore forming agent may comprise a polymer and / or a carbohydrate (e.g., starch) having a decomposition temperature (a) above the drying temperature of the green extrudite and (b) at or below the calcination temperature. The pore forming agent functions as a fugitive material that is present in the precursor paste and the extrudate before and after drying, but is absent from the consolidated extrudate formed upon calcination. Removal of the pore forming agent during calcination leads to the creation of a population of pores, preferably mesopores of 2-50 nm in width and / or diameter, within the extruded alumina composite. In some examples, the pore forming agent may comprise a water-soluble polymer. Suitable polymers may include polyethylene glycol (PEG), poly(N-vinylpyrrolidone) (PVP), a polyacrylamide, a polyacrylic acid copolymer, and / or a polysaccharide. The carbohydrate may comprise starch or sucrose. In the examples described below, the pore forming agent includes first and second pore forming agents, in particular, PEG and sucrose, although otherPCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 combinations of polymers and / or carbohydrates are possible. PEG may be provided in liquid form, and sucrose may be dissolved in water to ensure adequate molecular dispersion, such that the desired mesoporosity (as opposed to larger pores) in the final extruded alumina composite. Agglomeration of the sucrose, which may lead to a population of larger-size pores, may be avoided by thorough dissolution and mixing.

[0023] The extrusion aid may enhance the lubricity of the precursor paste to facilitate extrusion through a die. The extrusion aid may comprise a cellulosic polymer, a metallic stearate, an oil, and / or a fatty acid. For example, the extrusion aid may include methylcellulose or hydroxypropyl methylcellulose, which are available commercially under the tradename Methocel™, mineral oil, tall oil, and / or sodium stearate. The liquid carrier may comprise water, such as deionized (DI) water.

[0024] In some examples, the precursor paste may include the liquid carrier (e.g., DI water) at concentration from 30 to 45 wt.%; the gamma alumina powder at a concentration from 15 to 30 wt.%; the boehmite powder at a concentration from 5 to 12 wt.%; the porous inorganic filler at a concentration from 5 to 12 wt.%; the pore forming agent at a concentration from 18 to 35 wt.%; and the extrusion aid at a concentration from 1 to 3.5 wt.%.

[0025] The porous inorganic filler, gamma alumina, boehmite, extrusion aid and / or other constituents employed in the precursor paste are commercially available from various vendors, such as Sigma-Aldrich (Burlington, MA) and other chemical companies. Other additive(s) known in the art may be added to the precursor paste as needed to influence rheology, dispersion, or other properties.

[0026] Mesoporous alumina composites extruded from these formulations and processed as described in this disclosure may have a high porosity, high pore volume, and / or a mesoporous pore size. For example, the extruded mesoporous alumina composite may have a porous structure comprising a porosity of greater than 65%, a pore volume of at least about 0.9 cc / g, and / or a D50 pore size of 0.1 pm or less. As indicated above, it is preferred that the porosity is predominantly or entirely mesoporosity, with pore sizes falling in the range from 2 nm to 50 nm (z.e., from 0.002 pm to 0.05 pm). Accordingly, the D50 pore size is preferably 0.05 pm or less, or 0.03 pm or less, and / or as low as 0.01 pm, or as low as 0.005 pm. ThePCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066D50 pore size represents the pore size corresponding to a cumulative frequency of 50%, or the median. For example, for a D50 pore size of 0.03 pm by volume distribution, the volume of pores of 0.03 pm or less accounts for 50% of the total sample volume, and the volume of pores greater than 0.03 pm is also 50%. In some examples, the pore volume may be at least about 1 cc / g, at least about 1.3 cc / g, and / or as high as about 2 cc / g, or as high as about 1.5 cc / g. The porosity may be at least about 70%, or at least about 75%, and / or as high as about 80%. Advantageously, despite the high porosity, the mesoporous alumina composite has sufficient mechanical integrity to serve as a robust support for amines or other active materials. Accordingly, the extruded mesoporous alumina composite may further include amine functional groups on exposed surfaces thereof.

[0027] EXAMPLES

[0028] Extruded mesoporous alumina composites were fabricated as described below. The first step was preparation of exemplary precursor pastes (“Example 1” and “Example 2”) having the compositions shown in Table 1.Table 1. Compositions of Exemplary Precursor Paste Formulations

[0029] Example 1

[0030] The precursor paste was prepared by mixing and compounding 20.37 parts gamma alumina (Puralox™ TH 100 / 150, Sasol Ltd.), 9.31 parts sepiolite, 7.54 parts boehmite, 9.45 parts sucrose, 12.63 parts PEG 300, 2.55 parts methocel, 0.65 parts sodium stearate, and 37.51 parts DI water. The precursor paste then underwent extrusion using a ram extruder toPCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 form a green extrudate. The green extrudate was dried by heating at 120°C in air, and then the dried extrudate underwent calcination at 650°C for 2 hours, also in air. The resulting extruded mesoporous alumina composite was characterized to obtain pore structure characteristics. The pore structure data are presented in Table 2 in comparison with data from cordierite. Measurements were made using Micromeritics Autopore IV 9520 Mercury Porosimeter (porosity), the Micromeritics 3Flex instrument (pore volume and pore size distribution), and the Micromeritics TriStar Unit (BET surface area). Scanning electron microscope (SEM) images of portions of the extruded mesoporous alumina composite postcalcination are shown in FIGS. 3 A (150X magnification) and 3B (500X magnification). The pore size distribution is shown in FIG. 4.

[0031] Example 2

[0032] The precursor paste was prepared by mixing and compounding 18.0 parts gamma alumina (Puralox™ TH 100 / 150, Sasol Ltd.), 11.7 parts sepiolite, 9.9 parts boehmite, 14.22 parts sucrose, 14.22 parts PEG 300, 2.25 parts methocel, 0.58 parts sodium stearate, and 29.12 parts DI water. The precursor paste then underwent extrusion using a ram extruder to form a green extrudate, paste then underwent extrusion using a ram extruder to form a green extrudate. The green extrudate was dried by heating at 120°C in air, and then the dried extrudate underwent calcination at 650°C for 2 hours, also in air. The resulting extruded mesoporous alumina composite was characterized to obtain pore structure characteristics. The pore structure data are presented in Table 2 in comparison with data from cordierite. Measurements were made using Micromeritics Autopore IV 9520 Mercury Porosimeter (porosity and pore size) and the Micromeritics 3Flex instrument (pore volume and pore size distribution). The pore size distribution is shown in FIG. 5.Table 2. Pore Structure Characteristics of Extruded Mesoporous Aluminum Composites compared to CordieritePCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066

[0033] To clarify the use of and to hereby provide notice to the public, the phrases "at least one of , , ... and <N>" or "at least one of , , ... or <N>" or "at least one of , , ... <N>, or combinations thereof' or ", , ... and / or <N>" are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, ... and N. In other words, the phrases mean any combination of one or more of the elements A, B, ... or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed. Unless otherwise indicated or the context suggests otherwise, as used herein, "a" or "an" means "at least one" or "one or more."

[0034] While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations.

[0035] In addition to the features mentioned in each of the independent aspects enumerated above, some examples may show, alone or in combination, the optional features mentioned in the dependent aspects and / or as disclosed in the description above and shown in the figures.

Claims

PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066CLAIMSWhat is claimed is:

1. An extrudable formulation for making a mesoporous alumina composite, the extrudable formulation comprising: a precursor paste including: a liquid carrier; gamma alumina powder; boehmite powder; a porous inorganic filler; and a pore forming agent.

2. The extrudable formulation of claim 1, wherein the pore forming agent comprises a polymer and / or a carbohydrate.

3. The extrudable formulation of claim 2, wherein the polymer comprises a water-soluble polymer selected from the group consisting of polyethylene glycol (PEG), poly(N-vinylpyrrolidone) (PVP), a polyacrylamide, a polyacrylic acid copolymer, and a polysaccharide.

4. The extrudable formulation of claim 2 or 3, wherein the carbohydrate comprises sucrose and / or starch.

5. The extrudable formulation of any preceding claim, wherein the pore forming agent includes first and second pore forming agents.

6. The extrudable formulation of the preceding claim, wherein the first and second pore forming agents comprise polyethylene glycol (PEG) and sucrose.

7. The extrudable formulation of any preceding claim, wherein the porous inorganic filler comprises a clay mineral and / or volcanic ash.PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-0668. The extrudable formulation of any preceding claim, wherein the porous inorganic filler comprises sepiolite and / or pumice in particulate form.

9. The extrudable formulation of any preceding claim, further comprising an extrusion aid, wherein the extrusion aid comprises a cellulosic polymer, a metallic stearate, an oil, and / or a fatty acid.

10. The extrudable formulation of claim 9, wherein the extrusion aid is selected from the group consisting of: methylcellulose, hydroxypropyl methylcellulose, mineral oil, tall oil, and sodium stearate.

11. The extrudable formulation of either of claims 9 or 10, wherein the extrusion aid is at a concentration from 1-3.5 wt.%.

12. The extrudable formulation of any preceding claim, wherein the precursor paste has a plasticity configured to facilitate extrusion through a die and shape retention after extrusion.

13. The extrudable formulation of any preceding claim, wherein the precursor paste comprises a strain-rate dependent viscosity.

14. The extrudable formulation of any preceding claim, wherein the liquid carrier comprises water.

15. The extrudable formulation of any preceding claim, wherein the precursor paste includes: the liquid carrier at a concentration from 30-45 wt.%; the gamma alumina powder at a concentration from 15-30 wt.%; the boehmite powder at a concentration from 5-12 wt.%;PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-066 the porous inorganic filler at a concentration from 5-20 wt.%; the pore forming agent at a concentration from 18-35 wt.%.

16. A method of preparing an extrudable formulation for making a mesoporous alumina composite, the method comprising: forming the precursor paste of any preceding claim, the forming comprising: mixing together the gamma alumina powder, the boehmite powder, and the porous inorganic filler to form a dry mixture; preparing a liquid mixture comprising the pore forming agent; and combining the liquid mixture with the dry mixture and compounding to form the precursor paste.

17. The method of claim 16, wherein the pore forming agent includes first and second pore forming agents, and wherein preparing the liquid mixture comprises: dissolving the first pore forming agent in water to form an aqueous solution; and combining the second pore forming agent with the aqueous solution, thereby forming the liquid mixture.

18. The method of claim 17, wherein the first and second pore forming agents comprise sucrose and polyethylene glycol (PEG), respectively.

19. The method of any of claims 16-18, wherein the porous inorganic filler comprises a clay mineral and / or volcanic ash.

20. The method of any of claims 16-19, wherein the porous inorganic filler comprises sepiolite and / or pumice in particulate form.

21. The method of any of claims 16-20, wherein the mixing, preparing and combining occur at ambient pressure (e.g., 1 atm in air) and ambient temperature (e.g., 18- 25°C).PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-06622. A method of making an extruded mesoporous alumina composite, the method comprising: extruding a precursor paste comprising gamma alumina powder, boehmite powder, a porous inorganic filler, a pore forming agent, and a liquid carrier to form a green extrudate; drying the green extrudate to remove the liquid carrier, thereby forming a dried extrudate; heating the dried extrudate to a calcination temperature, whereby the pore forming agent is removed and the boehmite powder transforms to gamma alumina particles, thereby forming a consolidated extrudate.

23. The method of claim 22, further comprising, prior to extruding the precursor paste, preparing the precursor paste.

24. The method of claim 23, wherein preparing the precursor paste comprises: mixing together the gamma alumina powder, the boehmite powder, and the porous inorganic filler to form a dry mixture; preparing a liquid mixture comprising the pore forming agent in a liquid carrier; and combining the liquid mixture with the dry mixture and compounding to form the precursor paste.

25. The method of claim 24, wherein the pore forming agent includes first and second pore forming agents, and wherein preparing the liquid mixture comprises: dissolving the first pore forming agent in water to form an aqueous solution; and combining the second pore forming agent with the aqueous solution, thereby forming the liquid mixture.

26. The method of claim 25, wherein the first and second pore forming agents comprise PEG and sucrose.PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-06627. The method of any of claims 22-26, wherein the pore forming agent has a decomposition temperature above a drying temperature of the green extrudate and below the calcination temperature.

28. The method of any of claims 22-27, wherein the drying occurs at a drying temperature in a range from 100°C to 140°C.

29. The method of any one of claims 22-28, wherein the calcination temperature is in a range from about 550°C to about 850°C.

30. The method of any one of claims 22-29, further comprising impregnating the consolidated extrudate with a polyamine to form amine functional groups on an exposed surface thereof.

31. An extruded mesoporous alumina composite comprising: a porous structure comprising gamma alumina and a porous inorganic filler, the porous structure including: a porosity of greater than 65%; a pore volume of at least 0.9 cc / g; and a D50 particle size of 0.1 pm or less.

32. The extruded mesoporous alumina composite of claim 31 wherein the porous structure comprises a honeycomb geometry including a plurality of open channels extending longitudinally therethrough and being defined by porous cell walls comprising the gamma alumina and the porous inorganic filler.

33. The extruded mesoporous alumina composite of any of claims 31-32, wherein the pore volume is at least 1 cc / g, at least 1.3 cc / g, and as high 2.0 cc / g, or as high as 1.5 cc / g.PCT / US25 / 46515 16 September 2025 (16.09.2025)Atorney Docket No.: SP24-06634. The extruded mesoporous alumina composite of any of claims 31-33, wherein the porosity is at least 70%, or at least 75%, and / or as high as 80%.

35. The extruded mesoporous alumina composite of any of claims 31-34, wherein the D50 pore size is 0.05 pm or less, or 0.03 pm or less, and / or as low as 0.01 pm, or as low as 0.005 pm.

36. The extruded mesoporous alumina composite of any of claims 31-35 further comprising amine functional groups on exposed surfaces thereof.

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