WO2015077835A1

WO2015077835A1 - Pelletized form of a composite material and method of producing same

Info

Publication number: WO2015077835A1
Application number: PCT/AU2014/050376
Authority: WO
Inventors: Gregory Paul KNOWLES; Alan Loyd Chaffee
Original assignee: Monash University
Current assignee: Monash University
Priority date: 2013-11-26
Filing date: 2014-11-26
Publication date: 2015-06-04
Anticipated expiration: 2016-05-26

Abstract

A process for the preparation of a pelletized form of a composite material for gas separation applications, the composite material including a solid support material and at least one separate sorption active phase, wherein the process includes the following steps: a. treating the composite material with a gas to alter the physical characteristics of the at least one separate sorption active phase and transform the composite material into a different form to facilitate pelletization of the treated composite material; and, b. compressing or compacting the treated composite material to prepare the pelletized form of the composite material.

Description

, l -

PELLETIZED FORM OF A COMPOSITE MATERIAL AND METHOD OF

PRODUCING SAME

The present invention relates to a pelletized form of a composite material and a method of producing same. The present invention also relates to the use of a pelletized form of a composite material for gas separation applications.

Background

As an example of a composite material used for gas separation applications, adsorbents have been explored to facilitate CO2 .capture from mixed gas streams such as post combustion flue gas, syngas, natural gas and air to thereby satisfy the world' growing demand for energy whilst reducing the global atmospheric concentration of greenhouse gases in order to slow global warming / climate change. Many recent adsorbent technology developments have foeussed in particular o the preparation of suc materials as powders. However it has been recognized that pelletized sorbents will be preferable for pressure swing adsorption (PSA) and temperature swing adsorption (TSA) which are typical industrial gas separation processes.

As a specific example, Polyethyleneimine (PET) loaded with MCM-41 type mesoporous silica has been found to prepare a high capacity "molecular basket" type CO2 sorbent. PEI was subsequently loaded into mesoporous type silicas with substantially larger pore volumes such as SBA-15 and mesocellular siliceou foam (MCF), to prepare adsorbents with even greater PEI content (and thereby greater CO₂ capacity) bot per unit mass and per unit, space volume as are therefore more attractive for industrial applications.

Pelletization of MCF-PEI composites has been found to be problematic. Rather than forming pellets when the MCF-PEI composite material was subjected to compression forces, the material was found to extrude and/or become sticky. This was attributed to PETs being viscous liquids and the MCF-PEI composite material sorbents (at particularl high PEI loadings) thereby being essentially a solid in liquid dispersion and the presence of "tacky" or "sticky" PEI on the external surfaces of the support material

Therefore it is desirable to provide a. pelletized form of composite materials which find use in gas separation applications and a process for preparing same.

Summary

According to one aspect there is provided a process for the preparation of a pelletized form of a composite material for gas separation applications, the composite material including a solid support material and at least one separate sorption active phase, wherein the process includes the following steps:

a. treating the composite material with a gas to alter the physical characteristics of the at least one separate sorption active phase and transform the composite material into a different form to facilitate pelletization of tire treated composite material; and,

b. compressing or compacting the treated composite material to prepare the pelletized form of the composite material.

I one form, the process includes the further step c. treating the pelletized form of the composite material to provide at least a partial reversal of the alteration of the physical characteristics of the at least one separate sorption active phase in step a.

According to another aspect there is provided a process for the preparation of a pelletized form of a composite material for gas separation applications, the composite material including a solid support material and at least one separate sorption active phase, the process including the followin steps: combining the solid support material with the at least one separate sorption active phase vi sonication or vacuum infiltration to form the composite material; and, compressing or compacting the composite material to prepare the pelletized composite material. In one form the solid support material is selected from a material with: micropore si ty, mesoporosity or macroporosity or any combinations of the like to support the separate sorption active phase. In one form the solid porous support material is selected from silicas, aluminas, aluminosilieates, zeolites, clays, carbons, carbon nanotuhes, metal organic frameworks, organic frameworks, crystalline organic ^"frameworks or functionalised derivatives thereof. In one form the solid support material incorporates functional groups, in a further form the solid support material is selected from one of the following: MCF, 3BA-15 or Davisil 60 type mesoporous silicas. In one form the separate sorptio active phase is selected to be supported by the solid porous support material. In one for the separate sorption active phase is the active component utilised for the gas separation applications. In one form altering the physical characteristics of the at least one separate sorption active phase in step a. includes where at least one component of the separate sorption active phase transforms from liquid to a solid via gas sorption.

In one form the alteration of the physical characteristics of the at least one component of the separate sorption active phase may be reversed via a thermal and/or pressure swing or inert gas purge. In one form the separate sorption active phase is for applications involvin the separation of C0₂ from a gas stream.

In one form the composite material is treated with a gas including C(¾ in step a. In a further form the gas including C0₂ includes pure C0₂ or the gas includes at least about 20 wl% C(½. In. one form step a. includes treating the composite material wit a gas at a temperature of less than 110°. In a further form step a. includes treating the composite material with a gas at a temperature of between about 4Q°C and about 70°C. In still a further form step a. includes treating the composite material with a gas for a period of about 30 minutes to about 20 hours. In a further form step a. includes treating the. composite material with a gas for a period of about 10 hours to about 18 hours. In one form step c. includes placing the petietized composite material under vacuum or contacting the pelletked composite material with a purge gas. In a further form step c. includes placing the pelletized composite material under vacuum for a period of about 30 minutes to about 5 hours at a temperature of about 2Q°C to about 120°C. It a farther form the purge gas is an inert gas selected from nitrogen or argon or a combination of both.

In one form, the process as herein described further includes a step of pre drying the composite material which includes placing the composite material under vacuum or contacting the composite material with a purge gas. i one form the step of pre drying the composite material occurs during step a. when the composite material is treated with a gas.

In one form the separate sorption, active phase is selected from one or more of the following; primary, secondary or tertiary amines or amidines. in one form the primary secondary or tertiary amines or amidines comprise additional functionality suc as to provide steric hindrance or to facilitate hydrogen bonding, or .otherwise facilitate gas sorption. In one form the separate sorption active phase includes one or more of the following: alkylamines including diethylamine, ethyleneamine, ethylenediamine, diisopropylaniine (DIP), diethylenetriamine, tetraethylenepentamine (TBPA) or pentaethylenehexamine; alkaiiol amines including monoethanolamine (DEA), diethanol amine (DEA), isopropanol amine, diisopiOpanoIamine (DIP A), triethanolamme. N-methyldiethanolamine (MDEA), 2-amino-2-meth l-i-propanol (AMP), 2-amino-2- methyl- l-propanediol, 2-hydroxyethylpiperzine and β,β' -hydroxyaminoethy lether; amine polymers including polyethyleneimine (PE1)₅ polyaliylamine (PA A), and polypropyleneimiiie; acrylonitriie modified alkanolamines o alkylamines including acrylonitriie modified tetraethyelenpentamine (TEPAN); amine dendrimers including melamine dendrimer, polyaminoaniine dendrimer, DAB-Am-4 and DAB-Am-8; sterically hindered amines including 1 ,4-diazabicyclo-[5,4,0] undec-7-ene (DBU) and 1,5- diazabicyclo[4.3.0l non-5-ene (DBN); polyamidine, polyguanidine, 4-aminophenylamtne, paraphenylenediamme and 4-aminoethylaniline; other arylamittes, alkylarylamines, amidines, alkazid M, 1,8 p-nienthanediamine (MDA). and sarcosine; aminosilicones including l,3-bis(3-aniinopropyl)-l,3 ,3,3-tetramethyldsiloxane (GAP-0), l,3,5-tris(3- amin.opix>pyi)--l., 1 ,3^5-pentamethyltrisi]oxane (M'D'M^*) and lris(3- aniinQpropyldirat hylsiloxy)-3-aminopropykilaiie (M'3T^*); amino acids, and ionie liquids including diniethylethyienediamine (D EDAH) formate, (dimefhylamiiio)prapylaniin (DMAPAB) formate and lris(2aminoethyi)amine (TAEAH) formate and mixtures thereof. In one form the separate sorption active phase includes one or .more of the following: PEI, tetraethyleneperitanrine, polyally J amine, t.ris(2-aminoethyi)amine (TAEAH) formate, or DAB-Am-4. In one form the separate sorption active phase incorporates- additional compounds to provide hydrogen bonding such as alcohols, glycols, ethers includin glycerol or polyethyeleneglycol (PEG), to facilitate improved equilibrium gas sorption and/or gas sorption kinetics.

According to another aspect there is provided a pelletized composite material produced by the process as herein described. According to another aspect there is provided a use of a pelletized composite material as herein described as a sorbent for C0₂ capture.

Brief Description of the Accompanying Figures The present invention will become better understood from the following detailed description of various non-limitin embodiments thereof, described hi connection with the accompanying figures, wherein:

Figure 1 depicts the activation of MSG (4 days M₂ purge 110 °C, then 5 days under evacuation 1 10 °C, via Micromeritics Vac Prep 061 );

Figure .2 depicts the carbonation of activated composite MCF-PBl adsorbents;

Figure 3 depict the thermogravimetric results of CO? PPSA (1.05 °C) for lVl80-a, M85-a & M90-a (0, 2, 5,. 15, 30, 50, 30, 15, 5, 2 & 0 % C0₂ / Ar); and.

Figure 4 depicts the thermogravimetric results of C0₂ PPS A (105 °C) for M8()-p, M85-P & Μ90-Ρ (0, 2, 5, 15, 30, 50, 30, 15, , 2 & 0 % C0₂ / Ar). Detailed Description

The foregoing describes only some embodiments of the present invention, and modifications and/or changes can be made thereto without departing from the scope and spirit of the invention, the embodiments being illustrative and not restricti e.

In the context of this specification, the word "comprising" means 'Including principally but not necessaril solely" or "having" or "including", and not "consisting onl of. Variations of the word "comprising", such as "comprise" and "comprises" have corres pondi ngl y varied meani ngs .

The reference in this specification to any prior publication (or information derived from it), or to an matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior pubiicalion (or infomiation derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

As herein described Polyethylenimme (PEI) (or also known as polyaziridine) is a polymer with repeating unit composed of the amine group and two carbon aliphatic CH₂CH2 spacer. Linear PEIs contain all secondary amines and a terminal primary amine and branched PEIs contain primary, secondary and tertiary amino groups.

A herein described mesocellular siliceous foam (MCF) (or also known as MSF) is a mesoporous silica compound, MCF comprises uniformly sized large spherical cells that are interconnected by uniform windows to create a continuous 3-D pore system.

As herein described pelletizing or peiletization is the process of compressing a material into the shape of a pellet. In certain embodiments there is provided a process for the transfOTmation of composite materia) powders into robust pellets whereby the composite material powders before process of transformation typically extrude, partially extrude or form tacky pellets under compression force. I eertain embodiments the process neither involves incorporation of a permanent binder or non-reversible chemical modification of the composite material. In certain embodiments, the process, involves modifying those aspects of the composite materia] that otherwise render it not readily peilefizable by compression force in such a manner that can be readily reversed after peileiization to produce robust pellets of the composite material . In certain embodiments this relates to the reversible transformation (chemical or physical) of a separate sorption active component included as part of the composite material into a solid or more solid form to facilitate its pelietkadon and the subsequent reversal of this transformation process to re-form the composite material which remains in a pel!efeed form. Often when the separate sorption active phase is incorporated in the composite material during formation, this provides the composite material with physical characteristics such as tackiness, some tackiness, viscous, or even apparently (almost) solid type physical characteristics. Such physical characteristics provide that when the composite material comes under the influence of a compression force during a pelletixation process, the composite material will extrude, partially extrude or produce tacky pellets that are unsuitable when a robust pellet may be, desired. hi certain embodiments the composite material may be transformed from a solid in liquid dispersion into a solid in solid dispersion. In eertain embodiments the reversible transformation of the composite material may be embodied in a process for the preparation of a pelktized form of a eomposite material for gas separation applications, the composite material including a solid support material and at least one separate active sorption phase, wherein the process includes a first step a. which involves treating the eomposite material with a gas to transform the composite material into a different form to facilitate palletization of the treated composite material, in this step, the gas alters the physical characteristics of the separate sorption active phase to the extent that the composite materia! no longer tacky, viscous, semi solid, or solid in liquid dispersion when subjected to a compressive force during pellitization.

In certain embodiments, step a, is then proceeded by step b, which involves taking the treated composite material in which the physical characteristics of the at least one separate sorption active phase have been altered and compressing or compacting the composite material to prepare a pelletized form of the composite material. Once the composite material is in its pelletized form the composite material may undertake a further process step, step c. where the pelletized form of the composite material is treating to provide at least partial reversal of the alteration of. the physical characteristics of the separate sorption active phase.

In one example embodiment, MCF-PEI composite pellets can be prepared by first combining (loading) solid silica powder (MCF) with the viscous liquid polymer (PEI), then treating the MCF-PEI composite with carbon dioxide (CGj) to transform the viscous polymer component (PEI) into a more solid form (via for example carbamate, bicarbonate and or carbonate formation), then compressing the MCF-PEI solid / solid composite into pellet form, and then reversing the liquid to solid^■transformation by the application of heat and/or vacuum, and/or inert gas/vapour purge. It is a further embodiment that the transfonTiatio reversal may he first conducted upon use during application of the MCF- PEI which allow for the storage of the MCF-PEI composite in it solid / solid state.

According to certain embodiments it was surprisingly found that by providing an initial carhonation step to MCF-PEI composite material, the composite material undertook a physical change that facilitated the formation of pellets when the composite material is subjected to compression forces. Without wishing to be bound by theory, it was thought that providing an initial carbonation step converted the viscous liquid PEI into a solid which then facilitates the pelletization of the subsequent MCF-PEI composite material. In other words, the liquid amine phase was converted into a solid carbamate phase via CO2 chemisorption, According to certain embodiments it was also surprisingly found that combining the solid support material with at least one separate sorption phase via sonication or vacuum infiltration to form the composite material facilitated the penalization of the composite material, Without wishing to be bound by theory it is thought that, the benefits of sonication mixing or vacuum infiltration .concern facilitating infiltration and loading of the separate sorption phases to within the Internal porosity of the support materials.

According to certain embodiments the process as herein described may further include an ■Optional pre-drying step (eg vacuum or inert purge) to remove sorbed voiatiies from the composite materials such as may otherwise likely complicate their pelletii&ation. According to one example embodiment, the optional pre-drying step may even be accomplished by the gas treatment of the composite material in step a. as herein described.

In certain embodiments, the solid support, material as herein described may be selected irom a. material with; micropore si ty, mesoporosity or macroporosity or any combinations of the like to support the separate sorption active phase. The solid porous support material may be selected from silicas, aluminas, aiuminosilicates, zeolites, clays, carbons, carbon nanotubes, metal organic frameworks, organic frameworks, crystalline organic frameworks or fmictionalised derivatives thereof and the solid support material may incorporate functional groups.

In certain example embodiments, the solid support material i selected from one of the following: MCF, SBA-15 or Davisil 60 type rnesoporous silicas. In certain embodiments, the separate sorption active phase may be selected from one or more of the following: primary, secondary or tertiary amines or amidines. The primary secondary or tertiary amines or amidines may comprise additional functionality such as to provide steric hindrance: or to facilitate hydrogen bonding or otherwise facilitate gas sorption,

I certain embodiments, the separate sorption active phase may include one or more of the following-" alkyiamines including diethylamine. ethyleneamine, ethylenediaemine. diisopropylamine (DIP), diethylenetriamine, letraethylenepentamine (TEPA) or pentaelhylenehexamine; alkanolamines including monoethanol amine (DEA), diethanolamine (DEA), isopropanol amine, diisopropanoiamine (DIPA), triethanolamine, N-methyldiethanolamine (MDEA), 2-amino-2-rnethyi- 1 -propanol (AMP), 2-amino-2- methyl- 1 -propanediol, 2-hydroxyethylpiperzine and β,β'-hydroxyaminoe-thylether; amine polymers including polyethyleneimine (PEI), polyallylamine (P A), and polypropyleneimine' acrylonitrile modified alkanolamines or aikylamines including; acrylonitrile modified tetraethyelenpentaraine (TEPAN); amine dendrimers including melamine dendrimer, polyaniinoamme dendrimer. DAB-Am-4 and DAB -Am- 8; sterically hindered amine including l,4-diazahicyclo-S5,4,0|undec-7-ene (DBU) and 1 ,5- diazabicyelo[4..3.0] non-5-ene (DBN); polyamidine, polyguanidine, 4-aniinophenylamine, paraphenylenediamine and 4-aminoethylaniline; other arylamines, alkylaryiamines, amidines, alkazid M, 1.8 p-menthanediamine (MDA), and sarcosioe; aminosilicones including l,3-his(3-aminopropyi)- 1 , 1 ,3,3-tetramethyldsiloxane (GAP-0), 1 ,3,5-tfis(3- -miinopropyli-lJ.SJjS-pentamethyltiisiioxane (M'D'M') and tris(3- aminopropyktimethylsiloxy^*)-3-aminopropylsilane (M'3T'); amino acids, and ionic liquids including dimethyiethylenediamine (DMEDAH) formate, (dimethylamino)propylamiHe (DMAPAH) formate and tris(2aminoethyl)amine (TAEAH) formate and mixtures thereof. The separate sorption active phase may also incorporate additional compounds to provide hydrogen bonding such as alcohols, glycols, ethers including glycerol or polyethyeieneglycol (PEG), to facilitate improved equilibrium gas sorption and/or gas sorption kinetics.

The process and composite material as herein described will become better understood from the following e mples of preferred but no -limiting embodiments thereof.

Examples

The MCF was prepared via a neutral template technique using polyethyleneoxide- polypropyleneoxide-polyethyieneoxide block copolymer as template, tTimethylbenzene as swelling agent and template removal via calcination; hydrothemial treatment was conducted within glass reagent bottle contained within a pressure cooker as for 24 h at 105 °C, Th calcined product was found to have a BET surface area of -60S ra'g^' and pore volume of 2,84 inl.g^"1 (volume retained at p/pO = 0.90) as calculated from N₂ adsorption and desorption (77 K) isotherms (Micromeritics Tristar 3020).

The MCF was loaded with -80, 85 & 90 % pore volume equivalents t prepare composite materials comprising 7 .2, 72.4 and 73.9 wt % of branched av. 1200 MW PEI (50 Wt. % in HiO) via wet impregnation from efhanoi solution, the bulk solvents were removed via rotary evaporation under vacuum at 60 °C (2 h) to prepare the MCF-PEI composite crude products M80, M85, & M90 respectively.

.Crude product samples were subsequently activated under N₂, purge (4 days at 1 10 °C) and then 5 days under vacuum (5 days at 110 °C) to assess the thermal stability of the materials.

Crude product samples were also subsequently activated under N purge (24 h at 110 °C) and then in-vacuum (24 h at 110 ^'O to prepare the products M80-a. M85-a & M90-a.

Samples of each crude product were also activated unde vacuum (24 h at 1 10 °C) and then carbonated within a C0₂ purge at 20 °C (1 h), 60 °C (1. h), 60 °C (16 h) and 105 °C (1 h) via a Micromeritics VacPrep061. degassing station.

The crude, the activated and the pre-carbonated powder products alike (-0.2 g) were then compressed as prepared between 13 mm dia Specac pellet die via a Specac 15 ton press .(-10 min. at 8 ton) to prepare peiletlzed ^s'-p" products. The carbonated pellet products were then re-activated via vacuum (24 h at 1.10 °CJ to prepare their de-carbonated analogues.

General physico-chemical characterization of the materials preparation was supported by gravimetric analysis (Mettler-Toledo analytical balance) arid helium pycnometr (Micromeritics Accupyc 1340), The potential of the materials as adsorbents for CO₂ capture from post combustion flue gas was investigated via isothermal C(¾ partial pressure swing adsorption analysis (Setaram TAG24 simultaneous symmetrical, thermoanalyser) at 105 °C (under various conditions). Figure 1 shows the decrease in mass observed for M90 as the crude product was: first activated under N₂ purge (4 days) and the under vacuum (5 days) at 1 10 °C, This figure shows that the crude product lost a substantial fraction, of its mass over the first 24 hour period under N₂ purge. Minor furtiier mass loss was observed to occur over the subsequent 24 hour period, consistent with the removal of well retained volatiles, but the product appeared to be dried to essentially a constant mass after 1 day.

Table 1

ct vate .

Some further minor mass loss was subsequently observed to occur upon the application of vacuum, highlighting the potential of this activation technique to more effectively remove bot residual -solvent and any particularly volatile PEI fraction from this material. It is noted that the sample was not discoloured (as would be indicative of decomposition) in any way at this time. The preferred vacuum activation method (24 h at 110 °C) for the removal of residual solvent and any readily volatile PE1 fraction from the composite materials was adopted based on these results,

Table 1 summarises the observations made for compression .of the crude MCF-PEI powder produets as prepared, after vacuum activation (24 h at 110 °C) and following subsequent carbonation respectively. These results show that compression of the crude powder products entirely extruded around the pellet die under the applied compression force, consistent with a One solids in liquid dispersion. The vacuum activated products similarly exhibited substantial extrusion however some of the material was retained between the pellet die as a very sticky compacted layer {pellet). The pre-carbonated powders exhibited less extrusion and tackiness relative to the increasing aggressivenes of the applied carbonation conditions (extent of carbonation)..

111 carbonation at 20 °C led to preparation of very sticky pellets and much less product extrusion than with pre-aetivation alone. Carbonation fo h at 60 °C was sufficient to prevent product extrusion however still prepared sticky pellets which were not readily removable from the pellet die without loss of integrity. Carbonation for Ih at 105 °C led to the preparation of robust dry pellets however eac appeared slightl yellow consistent with minor decomposition which may have been due to urea formation. Prolonged 16h carbonation at 60 °C was found most useful to prepare robust dry pellets without decomposition . Figure 2 shows the extent of carbonation achieved for each of the acti vated powders under the various conditions applied. These results not only show that the extent of carbonation was enhanced by the more aggressive carbonation conditions employed, but also that the mass of the materials was found to increase by up to 18.5 wt % (4.2 mmol.g^"1) under the most aggressive condition consistent with the uptake of 0.25 molecules of CC¾ per amine atom present in the product. Furthermore each different powder product was found to essentially adsorb the same amount of C0₂ under the same carbonation conditions consistent with their similar theoretical PEI loadings.

Table 2 shows the nominal PEI loading of the crude MCF-PEI composite powders as determined b the mass amount of PEI^" initially mixed with the MCF together with the helium densities measured for the MCF, the activated MCF-PEI powders and the reactivated MCF-PEI pellets. These results show that the helium densities of all of the composites are substantially les than that of the MCF substrate, consistent with the greater nominal PEI content of these materials. It is also noted that the MCF-PEI composite powders exhibited greater densities than the analogous pellets, thought due to the greater potential for opportunistic fixation of atmospheric CO2 ^'to the more accessible sorption site within the powder products during sample transfer than to those of the analogous pellet products. Table 2 PEI loading and Helium density data.

Product ^amPEI dH ^best.PEI

(wt%) (ml.g^'1) (wt%)

MCF - 2,1 1. -

M80-a 71.2 1.30 63.6

M85-a 72.4 1,28 67.3

M90~ 73.9 1,28 66.4

^£M80-p 71.2 1.24 72.5

M85-p 72,4 1.23 73.0

cM Q-p 73.9 1 .21 76.3

a Initial mass amount of PEI in the product as initially calculated from the mass amounts of PEI and MCF combined .

b PEI loading estimated from the helium density measurements.

f^e Powders carbonated 16 h at 60 °C prior to pelletization & re-acti vation.

Table 2 also lists the PEI loadings estimated for each, composite from the helium density measurements assuming helium density of PEI to be the same as it liquid density (1.07 g.mT¹). These results show that the PEI loading estimates for the pellets are in very good agreement with the nominal PEI loadings (gravimetric analysis) consistent with the MCF and PEI being well mixed during synthesis prior to any component loss. The loadings estimated for the powder products essentially vary as expected, however are smaller than expected thought due to the fixation of opportunistic CO₂ as previously noted. These results highlight the potential of simple pyenonietry to readily estimate the PEI loading of such composite materials.

Figure 3 shows the thermogravimetric records obtained for CG₂ partial pressure swing adsorption processing of the activated powder products M80-a, 85-a and M9()-a via the thermogravimetric analyzer following in-situ 1 h re-activation under Ar purge at 110 °C These records sho that the mass of each activated powder product increased and decreased with the CO₂ partial pressure consistent with CO₂ sorption as expected. It is noted that the powder products exhibited up to 11 vvt % (2.5 mmol.g^"1) CO2 capacit (0.1.5 mol CO₂ er mol N) at CO₂ partial pressure of 0.15 (ie. simulated flue gas) as is a conservative estimate of their potential for C<¾ capture from post combustion flue gas via TS processing. It is also noted that these activated powder products exhibited up to 5 wt % (1.1 mmol.g^" ) working capacity (0.07 mol CO₂ per mol N) between CO₂ partial pressures 0.15 and 0.05 as is a conservative indication of their potential C(¾ workin capacity for C0₂ capture from post combustion flue gas via PSA processing.

Figure 4 shows the thermogravimetric records obtained for CO₂ partial pressure swing adsorption processing of the analogous set of re-activated (de-carbonated) pellet products M80-p, M85-p and 90-p, prepared via pelletization of their respective powder analogues following pre-carbonation for 16 h at 60 °C. These results show that C0₂ sorption for the pelleti ed products varies with the CO? partial pressure similarly to their respective powder products, but with only up to ~9 wt % (-2.0 mmol.g^"1) working capacity (0.12 mol C0₂ per mol N) for TSA type processing and onl up to -4 wt % (-0. mmol.g^"1) working capacity (0.05 mol CO₂ per N) for PSA type processing. The reduction in these working capacities s in each case attributed to compaction of the sorbent further limitin diffusion of gas (CO2) to / from the sorption sites. PEI was loaded into MCF via wet impregnation t prepare MCF-PEI composite powders with 71..2, 72,4 and 73.9 wt % PEI respectively. Compression of the activated powders (vacuum 1 10 °C) led to extrusion thought due to the product effectivel being a solid in liquid dispersion. Carbonation (conversion of amines to carbamates) of the products overcame this problem leading to preparation of robust pellctteed. sorbent Be pycnometry was found useful to characterize the PEI loadings. The re-activated pellets were found to reversihiy adsorb C0₂ from a simulated flue (15 % C0₂ / Ar) with C0₂ working capacities of up to 4 wt % (mol.g ¹) for PSA type processing and up to 9 wt % (rool.g^"!) for TSA type processing. The pellets were albeit found to exhibit smaller working capacities than the analogous composite powders; nevertheless they were found to be very promisin for CQj capture from post combustion flue gas via either TSA or PSA processing. Pre-carbonalion of the MCF-PEI type adsorbent was found useful to readily prepare pelletized sorbent with potential to selectively capture C0₂ from post combustion flue gas via PSA or TSA.

Table 3 summarises the results for the compression (under ambient conditions) of a further range of solid amine type composite sorbents, a were prepared by loading PEI with MCF over a more extensive range of PEI loadings, by preparing such material at larger scale, by combining PEI with the alternate support materials SBA-15 and Davisil 60 type mesoporous silicas, and by combining other amines including tetraethylenepentamine, polyaliyiamine, tris(2-aminoeihyi)amine (TAEAH) formate and DAB- Am -4 with mesoporous silica support materials, via wet infiltration from/within ethanol solvent/dispersant within a continuously stirred reactor (stirred 24 h at room temperature) followed by solvent removal via rotary evaporation at 60 °^'C and subsequent drying within N_:2 purge at 60 °C,

The amine was combined with the porous support on the basis of the specified estimated mesopore volume equivalent of the support material typically prepared from 1 g of silica, two scaled up formulations Mc-1.00P.l 2 and Mc~PEl-80b, were prepared on the basis of -80 g of MCF. Table 3 also shows the results from compression of the composite sorbent powder similarly prepared by combining PEI with MCF by wet infiltration via a continuous stir reactor following .initial pre-sonication. of the combined, solution/dispersion, as. was intended to promote better infiltration of the polymer to within the internal porosity of the support material . Each of the products prepared as such was then compressed to form pellets following both degassing, via prolonged (minimum 24 h) vacuum activation at 5 1 10 °C (Mc-TP-100 at 25 °C only), and then separatel following subsequent treatment with COi gas purge at 60 °C for approximately 1.6 h. ( cl00P12 at 105 °C for 1 h). Two of the MCF- PEI type products were in addition compressed following "carbonation" in air (16 h at 60 °C) after initial activation. Table 3, in addition, also lists the nominal amine content, the helium density and amine loading as calculated from the helium density of the 1.0 pellets prepared via the carbonation route upon subsequent deearbonation. These results show the composite sorbent pellets to essentially comprise the amine content as per the initial production of the precursor composite powders.

For the MCF-PEI composites series, as prepared by wet infiltration via a continuou stirred 15 reactor at ~1 g MCF scale, it is noted that compression following activation alone leads to the production of sticky pellets in eac case, with typically large amounts of product extrusion accompanying pellet production for powders with higher PEI contents, and smaller amounts of product extrusion accompanying pellet production for powders with lesser amounts of PEL In contrast, ail the same powder products readily compressed to dr 20 robust white pellets when compressed following their carbonation after initial vacuum activation. Thus these results clearly substantiate the benefit of the carbonation to facilitate the production of dry robust pellets of MCF-PEI composite for composites prepared with the larger range of PEI loadings, extending from 60 to 100 % MCF mesopore volume equivalents.

?5

Similar results were observed for the products prepared at the larger seale (-80 g MCF basis). For Mcl0GP12, the MCF-PEI product prepare wit 100% MCF mesopore volume of PEI, a sticky pellet and a large amount of product extrusion is observed for its compression with activation alone, whereas a dry robust pellet is prepared without product 30 extrusion for its compression following its subsequent carbonation. The same result was observed for Mc-PEI-SOb excepting that a smaller amount, of product, extrusion was ohserved for compression following activation alone, consistent with its smaller PET content. These results thus demonstrate the scale-ability of this pellet production technology. 10 g of this same carbonated sorbent powder was also readily compressed to form via a TDP-6T automated single punch tablet press (with 4 mm o.d, standard quadrasect pellet die), thereby further highlighting the scale-ability of the technology.

For PEI products prepared combined via the conventional continuous stirred reactor with SBA-15 and Davisil 60 type, mesoporous silicas, compression following activation alone did not appear to exhibit the same complications as per the analogous MCF products. For the SBA-15 case a dry robust pellet was prepared, whereas for the Davisil. 60 case, only a brittle sandy pellet, which broke upon removal from tile die, could be prepared. However, a dry robust white pellet of eac product was readily prepared when the powder products were carbonated following initial activation prior to compression. These results demonstrate that the compression of suc composites following activation alone may not become complicated to the same extent, nor in the same manner, for different support types, however, the results demonstrate that the carbonation pre-compression technology is useful to prepare dry robust pellets of the composites in each case.

The products prepared combined via the conventional continuous stirred reactor alone with TEPA, PAA, TAEAH and DAB, compression following activation alone, also did not appear to lead to the same complications as for the PEI products, nor the same complications in each case. For Mc-TP- 100, a soft wet/greasy pellet was formed, whereas for Mc-PAA-1 0 a more robust greasy pellet was formed together with some flaky product extrusion. For Se-TAEAH-100 and 60-DAB-Gl a dry robust pellet was prepared in eac case. Nevertheless, when the products were compressed following carbonation post the initial activation, dry robust pellets were prepared in eac case. These results show that although carbonation may not be essential to the production of dry robust pellets for each composite sorbent type, it highlights that the benefit of the compression post carbonation technology to overcome such problems where they do exist, and to facilitate the production of dry robust pellets in each case. Fof the PEI composites prepared with MCF and SBA-15 type mesoporous silicas for which sonieation mixing was employed prior to mixing via the conventional stir reactor, the results are very similar to those for the analogous products prepared by mixing via the continuous stir reactor alone. Compression of the MCF supported PEI products following activation alone in each case preparing wet/greasy yet sturdy pellets, the product prepared via sonieation at 60 °C (Mc-PEI-100-s60) in addition leading to a substantive wet/greasy extrusion. That these results are essentially the same as for that observed when the PEI was combined with the MCF by mixing via the continuous stir reactor alone, does not suggest any particular advantage for the use of sonieation. However, for the other cases an apparent beneficial effect was apparent. Compression of the MCF supported .PA A. composite prepared via the sonieation route following activation alone apparently readil prepared a dry robust white pellet, likewise, so too did compression of the SBA- 15 composites loaded with TP (Sc-TP-iOO-s) and PEI (Sc-PEI- 100-s) respectively, following activation alone. Nevertheless, compression following carbonation post activation, where conducted, readil prepared a dry robust pellet in each ease, thus highlighting again the benefit of the carbonation pre-eompression technology. The results thus suggest the benefit of sonieation mixing, which i attributed to this process better facilitatin infiltration and loading of the sorben I . phases to within the internal porosity of the supports. Table 3 also shows the results obtained for the compression of the MCF-PEl products Me- PEklOO and Mc-PEI-SOb after activatio alone and after carbonation in air (16 h at 60 °C) following initial activation. The prolonged exposure of these sorbents to a concentrated C(¾ purge steam was previously found to facilitate the produciion of dry robust pellets, whereas their compression following activation alone was found to lead to the production of sticky pellets accompanied by product extrusion. These additional result show that the compression of these products following "carbonation" via the prolonged exposure to air at 60 °C led to the production of sticky pellets albeit without obvious product extrusion, in each case. These results are attributed to the particularly low concentration of C<¾ in air t facilitate sufficient carbonation, It is noted mat although lower process temperatures might improve the extent of carbonation, these would also increase the likely uptake of water, which it is thought would likely lead to complications for pellet production, and so would require the use of dry air streams.

Table 3:

Sample Type Nornene 1 ature

So - SBA-15 type mesoporous silica (template removed via calcination)

Sx - S B A- 15 type mesoporous silica (template removal via ethanol extraction)

MG - MCF type mesoporous silica (template removed via calcination)

Mx - MCF type mesoporous silica (template: removal via ethanol extraction)

D - Davisil type mesoporous silica (40, 60 or 1.20 anstrom av pore dia).

PEI - polyeihyleneimine (provided 50 wt % in ¾0 (Sigma-Aldrich),

PAA - polyallylamine (liquid (www hemicalhook-com), typicall supplied as H₂.0 solution ( 20 wt % Sigma-Aldrich) or salt powder)

TP - tetraethylenepent amine (Sigma-Aldrich Ti l 509 - viscous liquid, Mw=l 89.3 g/mo!) DAB-Am-4: Polypropylenimine tetramine dendrimer, generation 1 (viscous liquid, Mw 31.6.53 g/mol)

TAEAH - tri.s(2-animoethyl)amine (TAEAH) formate (viscous brown/yellow liquid). Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims

T e Claims:

1 . A process for the preparation of a pelletized form of a composite material for gas separation applications, the composite material including a solid support material and at least one separate sorption active phase, wherein the process includes the following steps:

a, treating the composite material with a gas to alter the physical characteristics of the at least one separate sorption active phase and transform the composite material into a different form to facilitate pelletization of the treated composite material; and,

b, compressing or compacting the treated composite material to prepare the pelletized form of the composite material

2. A process according to claim 1 including a further ste c. treating the pelletized form of the composite material to provide at least a paitiai reversal of the alteration of the physical characteristics of the at least one separate sorption active phase in step a.

3. A process for the preparation of a pelletized form of a composite material for gas separation applications, the composite material including a solid suppor material and at least one separate sorption active phase, the process including the following steps; combining the solid support material, with the at least one separate sorption active phase via sonication or vacuum infiltration to form the composite material; and, compressing or compacting the composite material to prepare the pelletized composite material .

4. A process according to any one of the preceding claims wherein the solid support material is selected from a material with: mieroporosity, mesoporosit o macroporosity or any combinations of the like to support the separate sorption active phase.

A process according to any one of the preceding claims wherein the solid porous support material is selected from, silicas, aluminas, ahiminosilicates, zeolites, clays, carbons, carbon nanotubes, metal organic frameworks, organic frameworks, crystalline organic frameworks or functionalised derivatives thereof,

A process according to any one of the preceding claims wherein the solid support material mcorporatfis functional groups.

A process according to any one of the preceding claims wherei the solid support material is selected from one of the following: MCF, SBA-1.5 or .Davis.il 60 type mesoporous silicas.

A process according to any one of the preceding claims wherein the separate sorption active phase is selected to be supported by the solid porous support material

9. A process according to any one of the preceding claims wherein the separate sorption active phase is the active component utilised for the gas separation applications.

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10. A process according to any one of claims I, 2 and 4 to 9 wherein altering the physical characteristics of the at least one separate sorption active phase in step a. includes where at least one component of the separate sorption active phase transforms from a liquid to a solid via gas sorption.

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1 1 . A process according to accordin to any one of claims 1, 2 and 4 to 10 wherein the alteration of the physical characteristics of the at least one component of the separate sorption active phase may be reversed via a thermal and/or pressure swing or inert gas purge,

12, A process according to any one of the preceding claims wherein the separate sorption active phase is for applications involving the separation of COa from a gas stream.

13. A process according to any one of claims 1. 2 and 4 t 12 wherein the composite material is treated with a gas including CO2 in step a.

14. A process according to claim 13 wherein the gas including C0₂ includes pure CO₂ or the ga includes at least about 20 wt C0₂.

15. A process according to any one of claims 1, 2 and 4 to 14 wherein step a. includes treating the composite material with, a gas at a temperature of less than 110°.

16. A process according to any one of claims 1, 2 and 4 to 15 wherein step a. includes treating the composite material with a gas at a temperature of between about 40°C and about 70°C.

17. A proces according to any one of claims 1, 2 and 4 to 16 wherein step a. includes treating the composite material with a gas for a period of about 30 minutes to about 20 hours.

18. A process according to any one of claims L 2 and 4 to 17 wherein step a. includes treating the composite material with a gas for a period of about 10 hours to about 18 hours.

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19. A process accordin to any one of claims 2 and 4 to 18 wherein step e, includes placing the pelletized composite material under vacuum or contacting the pelletked composite material with a purge gas.

20. A process according to claim 1 wherein step c, includes placing the pelletized composite material under vacuum for a period of about 30 minutes to about 5 hours at a temperature of about 20°C to about ί 20°C.

21. A process according to claim 19 wherein the purge gas is an inert gas selected from nitrogen or argon or a combination of both.

22. A process according to any one of the preceding claims further including a step of pre drying the composite material which includes placing the composite material under vacuum or contacting the composite material with. a purge gas.

23. A process according to claim 22 wherein the step of pre drying the composite material occurs during step a. when the composite materia! i treated with a gas.

24. A process according to any one of the preceding claims wherein the separate sorption active phase is selected from one or more of the following: primary, secondary or tertiary amines or amidines ,

25. A process according to claim 24 wherein the primary secondar or tertiary amines or amidines comprise additional functionality sueh as to provide sterie hindrance or to facilitate hydrogen bonding or otherwise facilitate gas sorption.

26. A process according to any one of the preceding claims wherein the separate sorption, active phase includes one or more of the following:- a!kylamines including d ietliyl amine, ethy leneamine, ethy lenediamine, dii soprop ylainine (D IP) . diethylenetriamine. tetraethylenepentamine (TEPA) or pentaethylenehexamine; alkanolamines including monoethanolamine (DEA), diethanolamine (DEA), isopropanolamine, diisopropanoiamine (D1PA), Methanol amine, N~ methyldiethanolamine (MDEA), 2-amino-2-methyl- l-propanol {AMP), 2-amino-2- metliyl-1 -propanediol, 2-hydro yethylpiperzine and (¾,P'-h\xlroxyaimnoetl ylether; amine polymers including polyethyleneimine (PET), polyallytamine (PA A), and polypropyleneimine; acrylonitrile modified alkanolamines or alkylamines including acrylonitrile modified telraetJhyelenpentamine (TEPAN); amine dendrimers including melamine dendiimer, polyaminoamine dendrimer, DAB-Am-4 and DAB- Am-8: sterically hindered amines including l,4-diazabicyclo-[S,4,0]undec-7-ene (DBU) and .l ,5-diazabicyelo[4.3.0] non-5-ene (DBN); polyamidine, polyguanidtne,

4-aniinop^'henyl amine, parap enylenediamine and 4-aminoethylaiiiIme; other arylarnines, alkylarylamines, amidines, alkazid , 1 ,8 p-menthanedi amine (MDA), and sarcosine; aminosiiicones including 1 ,3-bis(3--aminopropyl)- 1 , 1 3- tetrameihyldsiloxane (GAP-0), I3.»5-tris(3-amiiiopropyl)-l_?1.3,5,5- pentametby I txisi loxane (M ' D ^' M ' ) and tri s(3 -ami nopropy Idimet hylsiloxy) -3 - aminopropylsilane (M'3 ); amino acids, and ionic liquids including dimethylethylenediamine (DMEDAH) formate, (difflethyiafflino)propylamine (DMAPAH) formate and tris(2aminoethyl)amine (TAEAH) formate and mixtures thereof.

27. A process according to any one of the preceding claims wherein the separate sorption active phase includes one or more of the following; PEL tetraethyienepentamine, polyallylamine, tris(2-aminfjetliyl)amme (TAEAH) formate, orDAB~Am-4.

28. A process according to any one of the preceding claims wherein the separate sorption active phase incorporates additional, compounds to provide hydrogen bonding such as alcohols, glycols, ethers including glycerol or polyethyeleneglycol (PEG), to facilitate improved equilibrium gas sorption and/or gas sorption kinetics.

29. A pelletized composite material produced by the process according to any one of claims 1 to 28.

30. Use of a pelletized eoniposite material according to claim 29 as a sorbent for C0₂ capture.