CN103785347A - Composite oxide adsorbent for adsorption of medium/high temperature CO2 - Google Patents

Composite oxide adsorbent for adsorption of medium/high temperature CO2 Download PDF

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CN103785347A
CN103785347A CN201210425527.XA CN201210425527A CN103785347A CN 103785347 A CN103785347 A CN 103785347A CN 201210425527 A CN201210425527 A CN 201210425527A CN 103785347 A CN103785347 A CN 103785347A
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hydroxide
adsorbent
general formula
composite oxides
stratiform
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郭秀盈
程继红
王勇
孙琦
王胜平
马新宾
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Shenhua Group Corp Ltd
National Institute of Clean and Low Carbon Energy
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National Institute of Clean and Low Carbon Energy
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Abstract

The invention discloses a composite oxide adsorbent for adsorption of medium/high temperature CO2 and a preparation method thereof. The composite oxide adsorbent comprises a composite oxide obtained by dehydration of layered double/three hydroxide (LDH). The layered double/three hydroxide has a general formula of [(M11-yM2y)1-xM3x(OH)2]A<x/n><n->.mH2O (1), and in the general formula, M1 represents Ca, M2 represents one or more of Mg, Sr, Mn, Fe, Co, Ni, Cu and Zn, M3 represents one or more of Al, Cr, Mn, Fe, La, Ce, Ga and In, A<n-> represents one or more of CO3<2->, Cl<->, SO4<2->, NO3<->, OH<-> and ClO4<->, x is greater than 0 and less than or equal to 1.0, y is greater than or equal to 0 and less than 0.5 and m is greater than or equal to 0 and less than or equal to 8. The composite oxide adsorbent also contains a certain amount of alkali metal carbonate or alkali metal oxide.

Description

For absorption high temperature CO 2composite oxides adsorbent
Technical field
The present invention relates to middle high temperature CO 2adsorbent field, is used for absorption high temperature CO in particular to one 2composite oxides adsorbent and preparation method.
Background technology
To discharge the environmental pollution that carbon dioxide causes more serious due to unlimited, for how to remove or to catch CO from various mixed industrial gas or waste gas 2day by day become the focus of people's research.Particularly, in the gas purification process such as hydrogen gas production, natural gas processing and hydrocarbon refinement, remove or catch CO 2seem even more important.In the prior art, the relatively conventional CO that removes 2method be to adopt cellulose acetate ester or alcohol amine solvent to make CO 2from mist, separate, but these processing methods all require intake air temperature not higher than 200 ℃.Generally contain CO in separation 2high-temperature gas mixture body time all to wait until that the temperature of mist is cooled to 200 ℃ just can carry out below.
At present, also there are some to adopt CaO and Li 2zrO 3remove high temperature CO Deng solid adsorbent 2document and report, but these natural CaO, nanometer CaO and some Al 2o 3the adsorbents such as the CaO of load after high temperature adsorption-desorption repeatedly circulates, the easy sintering of CaO, CaO particle is constantly grown up, and causes CO 2can only react with surperficial CaO, and cannot react with the CaO of granule interior, cause adsorbance constantly to decline in cyclic process.According to the literature, Li 2zrO 3and Li 4siO 4have good absorption stability, but its theoretical adsorption capacity is all very little, Li 2zrO 3theoretical adsorption capacity only has 29wt%, Li 4siO 4theoretical adsorption capacity be 37wt%, add the expensive of Li, be not suitable for practical application.
In the recent period, more existing researchers begin one's study have large absorptive capacity and high absorb stability for absorption high temperature CO 2new adsorbent.
For example, US2011/0251056 discloses a kind of middle high temperature CO of laminar nano carbonate 2adsorbent, this adsorbent can be stablized 600 ℃ of above CO of absorption 2wherein introduce calcium acetate and prepare the layered double-hydroxide of nanoscale (LDH), layer structure is synthetic for template, and the initial conversion ratio of this adsorbent reaches more than 90%, after carbonating-decarburization acidifying circulation 100 times, the conversion ratio of this adsorbent does not even change.Although but this patent documentation discloses the precursor of layered double-hydroxide (LDH) as its adsorbent, final adsorbent is laminar nano carbonate, and is also in order to remove anion and unnecessary acetate ion to the calcination process of layered double-hydroxide.The final structure formula of the disclosed adsorbent of this patent documentation is Ca (Ac) 2-Al-CO 3, wherein Ac represents acetate ion.
US2006/0093540 discloses one selective clearing CO from multicomponent gas mixture 2to provide without CO 2the method of air-flow, the method realizes CO so that admixture of gas reacts the mode of formation metal carbonate with metal oxide, for example CaO 2removing.Afterwards, the calcining under at least part of vacuum environment of spent sorbents-metal carbonate discharges CO 2after, again become metal oxide and become fresh adsorbent.In this patent documentation the precursor of disclosed preferred adsorbent CaO be U.S. Lin Wude area containing hydrate of calcium (LH) and mesoporous winnofil (PCC).Described adsorbent it is said and can at 600 ℃, work.
US6280503 disclose a kind of at 300-500 ℃ from air-flow CO absorption 2method, the solid absorbent that wherein used contains calcium oxide, and preferably carry out modification with alkali carbonate or heavy carbonate, the atomic ratio of alkali metal and magnesium is controlled in the scope of 0.006-2.60, preferred adsorbent is to obtain by adding alkali metal ion and carbanion to form co-precipitation in magnesium salt solution, the atomic ratio of alkali metal and magnesium can adjust by water washing and precipitating thing, by dewatering and remove CO from hydroxyl magnesium carbonate 2can make the adsorbent of low surface area, the method is specially adapted to pressure the adsorption operations of fluctuation.
All disclosures of above-mentioned document are introduced with for referencial use in full at this.
Comprise that the disclosed adsorbent of prior art of above-mentioned patent documentation is in the time that reality is used, effect is not to be satisfied with especially, always has such or such defect, and therefore, exploitation is a kind of for absorption high temperature CO 2and the new adsorbent with large absorptive capacity and high absorption stability is very important.
The object of the invention is in the situation that overcoming above one or more even all defect, find a kind of for absorption high temperature CO 2and there is large absorptive capacity and the high new adsorbent that absorbs stability.
Summary of the invention
According to first aspect present invention, provide a kind of for absorption high temperature CO 2composite oxides adsorbent, it comprise or three hydroxide (LDH) dehydration two by stratiform and composite oxides, layered two or three hydroxide have following general formula (1):
[(M1 1-yM2 y) 1-xM3 x(OH) 2]A n- x/n·mH 2O （1）
Wherein, M1 is Ca; M2 is the mixture of any or they in Mg, Sr, Mn, Fe, Co, Ni, Cu and Zn; M3 is the mixture of any or they in Al, Cr, Mn, Fe, La, Ce, Ga and In, A n-for CO 3 2-, Cl -, SO 4 2-, NO 3 -, OH -and ClO 4 -in the mixture of any or they; 0<x≤1.0; 0≤y<0.5; 0≤m≤8.
Described adsorbent also can comprise the alkali carbonate or the alkali metal oxide that represent with following general formula (2):
M4 2cO 3, M4HCO 3or M4 2o (2)
Wherein, M4 is the mixture of any or they in Li, Na, K, Ru, Cs, and the mol ratios of the stratiform that the alkali carbonate that general formula (2) represents or alkali metal oxide and general formula (1) represent pair or three hydroxide are 0-0.2.
Preferably,, in above-mentioned general formula (1) and general formula (2), 0<y≤0.1; M2 is Mg; M3 is Al; M4 is Li, Na, K or their mixture.More preferably, two or three hydroxide of general formula (1) represents stratiform are Ca 1-xal x(OH) 2(CO 3) x/2; Wherein 0.1≤x≤0.35.
At above-mentioned adsorbent, layered two or three hydroxide dehydration refers to that thermal dehydration, mode comprise the various ways such as calcining, heating using microwave, infrared heating.Described middle high temperature CO 2refer to the CO that temperature is greater than 300 ℃ 2, above-mentioned middle high temperature CO 2can contain a certain amount of steam.
According to second aspect present invention, provide a kind of for absorption high temperature CO 2composite oxides absorbent preparation method, described method comprises the following steps successively: (1) uses coprecipitation, hydrothermal synthesis method, sol-gal process, two or three hydroxide of stratiform that deposition-precipitation method, infusion process, solid reaction process or the preparation of organic compound pyrolysismethod represent with general formula (1);
(2) or three hydroxide two to the stratiform making in above-mentioned steps (1) carry out thermal dehydration, form composite oxides adsorbent after dehydration.
In above-mentioned absorbent preparation method, the mode of described dehydration can comprise that calcining, heating using microwave, infrared heating etc. are multiple for mode well known to those of ordinary skill in the art.And the alkali carbonate representing with general formula (2) or alkali metal oxide can add in layered two or three hydroxide preparation process, or add in the composite oxides that form after its dehydration.
In above-mentioned absorbent preparation method, preferably, prepare two or three hydroxide of stratiform by coprecipitation, by the mode of calcining, it is dewatered subsequently, its detailed process is as follows:
(1) make M1 salting liquid, M2 salting liquid, M3 salting liquid and OH -aqueous slkali and/or CO 3 2-salting liquid, in the ratio co-precipitation in above-mentioned general formula (1), optionally carries out crystallization to coprecipitate subsequently, thereby makes two or three hydroxide of the stratiform representing with general formula (1);
(2) the two or three hydroxide 1-10 hour of the stratiform that makes in calcining step (1) at 500-1100 ℃, obtain described composite oxides;
(3) optionally, in above-mentioned steps (1) or after above-mentioned steps (2), in being 0-0.2 with layered mol ratios two or three hydroxide, ratio adds the alkali carbonate or the alkali metal oxide that represent with general formula (2).
In above-mentioned absorbent preparation method, more preferably, described M1 salting liquid, M2 salting liquid and M3 salting liquid are nitrate; OH -aqueous slkali is LiOH, NaOH and/or KOH; CO 3 2-salting liquid is Na 2cO 3and/or (NH 4) 2cO 3.
Particularly preferred above-mentioned absorbent preparation method, comprising:
(1) at 60～90 ℃ by the nitrate solution of M1, M2 and M3 and LiOH, NaOH and/or KOH solution and/or Na 2cO 3and/or (NH 4) 2cO 3the molar ratio that solution is pressed in general formula (1) mixes, and strong stirring 0.5～1.0 hour forms the liquid containing coprecipitate, and elimination liquid, obtains coprecipitate;
(2) optionally, above-mentioned coprecipitate is inserted in reactor, make its crystallization 10-24 hour at 80-160 ℃;
(3) repeat afterwards washing and filter, until pH value unchanged after, be dried, obtain two or three hydroxide of the stratiform representing with general formula (1);
(4) the two or three hydroxide 1-10 hour of the stratiform that makes in calcining step (3) at 500-1100 ℃, obtain described composite oxides;
(5) alkali carbonate or the alkali metal oxide that optionally, represent to the general formula (2) that to add with layered mol ratios two or three hydroxide in the composite oxides that obtain in above-mentioned steps (4) be 0-0.2; Or the alkali carbonate or the alkali metal oxide that in the coprecipitation process of above-mentioned steps (1), add the general formula (2) of above-mentioned quantity to represent.
In above-mentioned absorbent preparation method, most preferably, M1 is Ca; M2 is Mg; M3 is Al; M4 is Li, Na, K or their mixture.
Accompanying drawing explanation
The Figure of description that forms a description part of the present invention is used for the present invention to be further explained; exemplary embodiment of the present and explanation thereof are for explaining in detail the present invention; so that those of ordinary skills are expressly understood essence of the present invention more, it does not form any restriction to protection domain of the present invention.In the accompanying drawings:
Fig. 1 has provided the atomic structure schematic diagram of the two or three hydroxide representative instances of stratiform of the present invention;
Fig. 2 has provided the microstructure schematic diagram of composite oxides adsorbent representative instance of the present invention;
Fig. 3 has provided the adsorption capacity of composite oxides adsorbent representative instance of the present invention with the trend schematic diagram of cycle-index variation;
Fig. 4 has provided composite oxides adsorbent representative instance of the present invention, nanoscale CaO and the micron order CaO adsorption capacity contrast schematic diagram with the trend of cycle-index variation;
Fig. 5 has provided stratiform of the present invention XRD two or three hydroxide representative instances to scheme;
Fig. 6 is that the XRD two or the composite oxides adsorbent that three hydroxide obtain through calcining of stratiform shown in Fig. 5 scheme; And
Fig. 7 has provided the adsorption capacity of composite oxides adsorbent representative instance of the present invention and existing adsorbent with the trend contrast schematic diagram of cycle-index variation.
The specific embodiment
It should be noted that, in the situation that mutually not conflicting, the numerous features in the embodiment of the present invention and embodiment can combine mutually.Carry out to explain in detail below with reference to the accompanying drawings and in conjunction with the embodiments the present invention.
Composite oxides adsorbent of the present invention can be more than 300 ℃, for example, under the middle high temperature of 500 ℃～700 ℃ with CO 2there is carbonation reaction and then CO absorption 2thereby, by CO 2from mist, remove.Layered layer structure two or three hydroxide can make M1, the M2 and the M3 composite oxides adsorbent high degree of dispersion that after calcining, obtain, thereby reduce its crystal particle scale and adsorption and desorption temperature, simultaneously improved again the anti-caking power of composite oxides adsorbents and to CO 2realize the stability of circulation absorption, and then guaranteed high temperature CO in the absorption of composite oxides adsorbent 2time there is the absorption property stability of higher adsorption capacity and long-term circulation.Composite oxides adsorbent of the present invention can be applicable to the mixed gas purification producing in the chemical reactions such as methanation, water-gas and methane reforming and therefrom removes CO 2.
Because CO3 2-after calcining, can not leave impurity, so general formula (1) [(M1 1-ym2 y) 1-xm3 x(OH) 2] A n- x/nmH 2a in O n-be preferably CO3 2-.
When M1 in above-mentioned general formula (1) is Ca, M3 is that Al and y get 0 o'clock, and layered two or three hydroxide are calcium hydroxide aluminium, and general molecular formula is Ca 1-xal x(OH) 2(CO3) x/2.Now describe the concrete molecular structure of two or three hydroxide (LDH) of stratiform in detail as an example of calcium hydroxide aluminium example.Fig. 1 is the atomic structure schematic diagram of stratiform calcium hydroxide aluminium.As can be seen from Figure 1, the layer of layered composite metal hydroxides replaces ordered arrangement by bivalent metal ion and trivalent metal ion and forms, between anion insert layer, be used for positive charge in balance layer, its complementary space of interlayer is occupied by the crystallization water, so just forms layer structure as shown in Figure 1.Two or three hydroxide (LDH) material of stratiform has at least tertiary structure, i.e. main body hydroxide layer, interlayer object anion and constitution water molecule.Layer is mainly formed by coordinate bond by metal ion and hydroxyl, metal ion in body layer has the isomorphous can substituted, intermediary water molecule has the effect of two or three hydroxide (LDH) structure of stable stratiform, between intermediary water molecule and layer and anion, mainly mutually combine with hydrogen bond action, it is reversible at a certain temperature removes or adsorbs.
In fact, two or three hydroxide of above-mentioned stratiform itself just have middle high temperature adsorption CO 2effect, but its adsorption capacity is limited.Composite oxides adsorbent of the present invention is derived two or three hydroxide structures from above-mentioned stratiform, in described composite oxides structure, together with divalence M1, M2 are interweaved with trivalent M3 metal ion, the M1, the M2 metal oxide that are conducive to generate in calcination process keep less crystal grain, and can not cause M1, M2 oxide grain to grow up because of calcining.
Composite oxides adsorbent of the present invention can be used for the mixed gas purification of the chemical reaction generations such as methanation, water-gas and methane reforming and removes CO from situ 2.In above-mentioned middle high temperature adsorption course of reaction, remove CO through directly adsorbing 2can overcome the restriction suffered because of thermodynamical equilibrium, and then fast reaction speed, improve the thermal efficiency of whole course of reaction.Middle high temperature refers to more than 300 ℃ herein, refers in particular to 500 ℃～700 ℃.
Composite oxides adsorbent of the present invention is at middle Removal under High Temperature CO 2principle be to utilize carbonation reaction to carry out the cyclic process of adsorption-desorption, generally, the oxide in composite oxides adsorbent is in the time of 500 ℃～700 ℃ and CO 2carbonation reaction occurs, and Formed hydrochlorate, has so just removed the CO in mist 2, this is an adsorption process; And carbonate decomposes while being heated to 700 ℃～850 ℃, discharge again CO 2, and this is a desorption process, so just can catch CO by gathering-device 2thereby, avoid air pollution.
At general formula (1) [(M1 1-ym2 y) 1-xm3 x(OH) 2] A n- x/nmH 2in O, preferably, 0≤y≤0.1, more preferably, 0≤y≤0.05.Y takes from above-mentioned scope can guarantee that in composite oxides adsorbent, active component CaO content is higher, and has high activity, this be because in composite oxides adsorbent M2 itself not with CO 2reaction, Main Function is impel active component CaO to form little crystal grain and improve its activity.Therefore along with y value increases, active component CaO content reduces, and adsorption capacity can decline, and adjuvant component M2 increases and there will be dephasign to affect on the contrary CO 2adsorption-desorption process.
In composite oxides adsorbent of the present invention, M2 and M4 metal ion are all as adjuvant component, and its addition is little, and two or three hydroxide of stratiform derive composite oxides structure through calcining.
Preferably, M2 is Mg, and M3 is Al, and M4 is the mixture of any or they in Li, Na and K.Now, stratiform is two or three hydroxide structures are better, because the fusing point of Li, Na or K salt is lower, the adsorption temp of the composite oxides adsorbent that calcining obtains can slightly reduce because of the oxide that contains Li, Na or K, and this is because M4 and M1 and M2 formation solid solution can reduce the CO of composite oxides adsorbent 2adsorption and desorption temperature, thus be conducive to save CO 2trapping energy consumption.
Preferably, above-mentioned stratiform general molecular formula two or three hydroxide are Ca 1-xal x(OH) 2(CO 3) x/2, wherein 0.1≤x≤0.35.Now, the composite oxides adsorbent obtaining through calcining has larger adsorption capacity and good circulation absorption heat endurance, and this is because the layer of layered composite metal hydroxides replaces ordered arrangement by bivalent metal ion and trivalent metal ion to be formed, and makes Al 3+ion high degree of dispersion is at Ca 2+around ion, it still can keep less crystallite dimension through calcining CaO, and it is by Al 2o 3crystal grain or metastable CaAl oxide, as CaAl 4o 7, CaAl 2o 4, Ca 3al 2o 6, Ca 12al 14o 33deng encirclement, in adsorption-desorption cyclic process, CaO crystal grain is difficult for growing up, and the CaO crystal grain that size is less has guaranteed CaO and CO 2contact more fully and react, thereby having kept higher CO 2adsorption activity and heat of adsorption stability.If it is large that CaO granularity becomes, because forming thicker CaCO around 3layer and cause CO 2be difficult to through diffusing into granule interior, the CaO active component of granule interior just cannot participate in CO 2absorption process.
Composite oxides adsorbent of the present invention can preferably contain useful general formula (2) M4 2cO 3or M4 2the alkali carbonate that O represents or alkali metal oxide, its can be in above-mentioned stratiform add in two or three hydroxide preparation process or the composite oxides that form afterwards in calcining in add.
The preparation method of composite oxides adsorbent of the present invention is simple, and does not need large-scale instrument and equipment, is suitable for suitability for industrialized production.
In the preparation method of composite oxides adsorbent of the present invention, preferably, prepare two or three hydroxide of stratiform by coprecipitation, make its dehydration by the mode of calcining subsequently, wherein, alkaline solution used can be sodium hydroxide solution, sodium carbonate liquor, sal volatile or their mixed solution.Adopt mixed solution mainly to consider that co-precipitation easily occurs for hydroxide ion and/or carbanion, in addition, the alkali carbonate representing with general formula (2) or alkali metal oxide solution are after filtration, may have part alkali metal ion and remain in final composite oxides adsorbent with oxide form after washing and calcining, these strong basicity alkali metal ions increase the effect of oxide basic sites as the oxide of Li, Na, K plays, can promote composite oxides adsorbent to CO 2absorption, improve the adsorption and desorption efficiency of composite oxides adsorbents.The oxide of M4 can add with the form of alkali metal soln in the process before composite oxides form, also can directly join in final composite oxides with the form of alkali metal oxide, but the former adds mode more even, promote the better effects if of adsorption and desorption.
Conventionally the autoclave that, coprecipitate can be put into 80 ℃～160 ℃ carries out crystallization 10～24 hours.Wash afterwards, filter repeatedly, until the pH of cleaning solution no longer changes, then precipitated crystal thing is put into the drying box inner drying 10～24 hours of 100～120 ℃, obtain two or three hydroxide of above-mentioned stratiform, put it into afterwards in Muffle furnace or calcining furnace and calcine, generally one-tenth two according to above-mentioned stratiform or three hydroxide assigns to determine calcining heat.But it should be noted that: above-mentioned crystallization process is optional, rather than essential.
The present invention is for absorption high temperature CO 2the mist of composite oxides adsorbent, for example 1%-10% steam a certain amount of to containing in CO 2adsorption effect the best.
Embodiment
(1) prepare composite oxides adsorbent
Embodiment 1
By calcium nitrate and aluminum nitrate aqueous solution and NaOH and aqueous sodium carbonate with Ca 0.65al 0.35(OH) 2(CO 3) 0.175the mol ratio of middle defined is inserted in mixer, mixing below limit at 60 ℃ stirs, make it co-precipitation, filter and obtain coprecipitate afterwards, by coprecipitate crystallization 10 hours in 80 ℃ of autoclaves, through 4 washings with filter, cleaning solution pH no longer changes, put into afterwards 100 ℃ of drying box inner dryings 10 hours, obtaining molecular formula is Ca 0.65al 0.35(OH) 2(CO 3) 0.175layered double-hydroxide.Above-mentioned layered double-hydroxide is put into 500 ℃ of Muffle furnaces and calcine 4 hours, obtain composite oxides adsorbent of the present invention.
Embodiment 2
By calcium nitrate and aluminum nitrate aqueous solution and NaOH and aqueous sodium carbonate with Ca 0.9al 0.1(OH) 2(CO 3) 0.05the mol ratio of middle defined is inserted in mixer, mixes below limit stir at 90 ℃, makes it co-precipitation, filter and obtain coprecipitate afterwards, by coprecipitate crystallization 24 hours in 160 ℃ of autoclaves, through 5 washings with filter, cleaning solution pH no longer changes.Put into afterwards 120 ℃ of drying box inner dryings 24 hours, obtaining molecular formula is Ca 0.9al 0.1(OH) 2(CO 3) 0.05layered double-hydroxide.Above-mentioned layered double-hydroxide is put into 1100 ℃ of calcining furnaces and calcine 12 hours, obtain composite oxides adsorbent of the present invention.
Embodiment 3
By calcium nitrate, magnesium nitrate and aluminum nitrate aqueous solution and NaOH and aqueous sodium carbonate with (Ca 0.9mg 0.1) 0.9al 0.1(OH) 2(CO 3) 0.05the mol ratio of middle defined is inserted in mixer, mixes below limit stir at 75 ℃, makes it co-precipitation, filter and obtain coprecipitate afterwards, by coprecipitate crystallization 16 hours in 120 ℃ of autoclaves, through 6 washings with filter, cleaning solution pH no longer changes.Put into afterwards 110 ℃ of drying box inner dryings 17 hours, obtain molecular formula for (Ca 0.9mg 0.1) 0.9al 0.1(OH) 2(CO 3) 0.05stratiform three hydroxide.Above-mentioned stratiform three hydroxide are put into 800 ℃ of calcining furnaces and calcine 8 hours, obtain composite oxides adsorbent of the present invention.
Embodiment 4
By calcium nitrate and aluminum nitrate aqueous solution and NaOH and the amine carbonate aqueous solution with Ca 0.7al 0.3(OH) 2(CO 3) 0.15the mol ratio of middle defined is inserted in mixer, mixes below limit stir at 75 ℃, makes it co-precipitation, filter and obtain coprecipitate afterwards, by coprecipitate crystallization 16 hours in 120 ℃ of autoclaves, through 6 washings with filter, cleaning solution pH no longer changes.Put into afterwards 90 ℃ of drying box inner dryings 10 hours, obtaining molecular formula is Ca 0.7al 0.3(OH) 2(CO 3) 0.15layered double-hydroxide.Above-mentioned layered double-hydroxide is put into 800 ℃ of calcining furnaces and calcine 8 hours, obtain composite oxides adsorbent of the present invention.
Embodiment 5
By in above-described embodiment 3 by (Ca 0.9mg 0.1) 0.9al 0.1(OH) 2(CO 3) 0.05stratiform three hydroxide calcine the composite oxides and the Na that obtain 2cO 3with Na 2cO 3/ (Ca 0.9mg 0.1) 0.9al 0.1(OH) 2(CO 3) 0.05mol ratio is 0.1 ratio mixing, obtains composite oxides adsorbent of the present invention.
Embodiment 6
By calcium nitrate and aluminum nitrate aqueous solution and NaOH and the amine carbonate aqueous solution with Ca 0.7al 0.3(OH) 2(CO 3) 0.15the mol ratio of middle defined is inserted in mixer, afterwards with K 2cO 3/ Ca 0.7al 0.3(OH) 2(CO 3) 0.15 mol ratios are that 0.05 ratio adds K 2cO 3the aqueous solution, mixes below limits at 75 ℃ and stirs, and makes it co-precipitation, filters and obtains coprecipitate afterwards, and by coprecipitate crystallization 16 hours in 120 ℃ of autoclaves, through 6 washings with filter, cleaning solution pH no longer changes.Put into afterwards 90 ℃ of drying box inner dryings 10 hours, obtaining molecular formula is Ca0.7Al 0.3(OH) 2(CO 3) 0.15layered double-hydroxide+K 2cO 3mixture.By above-mentioned layered double-hydroxide and K 2cO 3mixture put into 800 ℃ of calcining furnaces calcining 8 hours, obtain composite oxides adsorbent of the present invention.
(2) test compound oxide adsorbent performance
Embodiment 7
Adopt thermogravimetric analyzer (TGA) test composite oxides adsorbent of the present invention at 600 ℃ to by 50%CO 2, 45%N 2with the CO in the mist of 5% steam composition 2absorption property, test afterwards its pure N at 700 ℃ 2in desorption effect, wherein adopt in embodiment 3 by calcining Ca 0.7al 0.3(OH) 2(CO 3) 0.15the composite oxides adsorbent obtaining, Fig. 2 has provided the micro-structure diagram of this composite oxides adsorbent; Fig. 3 has provided the curve that this composite oxides adsorbent adsorption capacity changes with adsorption-desorption cycle-index.
Calcine Ca from shown in Fig. 2 0.7al 0.3(OH) 2(CO 3) 0.15in the SEM figure of gained composite oxides sample of sorbent, can find out, the crystallite dimension of calcining gained composite oxides adsorbent is substantially below 50 nanometers, and crystallite dimension is less is conducive to increase adsorption capacity and heat of adsorption stability.
From Fig. 3, can obviously find out, above-mentioned composite oxides adsorbent is CO after front 8 circulations of experience 2adsorption capacity is reduced to 47 % by weight from 55 % by weight, but being next slowly elevated to again 55 % by weight in 9-38 circulation, and later until the 216th circulation, it does not also change, and absorption property changes more stable with cycle-index.CO in front 8 circulations 2when adsorption capacity slight reduction is because has just started, composite oxides adsorbent internal structure is not very regular, and in cyclic process, along with continuous effect and the adjustment of adsorbent, hole is tending towards evenly gradually, so downward trend no longer appears in adsorption capacity afterwards.As can be known from Fig. 3, composite oxides adsorbent of the present invention has very high CO 2adsorption capacity and preferably adsorption-desorption cycle thermal stability.A circulation probably needs 4 hours.
Comparative example 1
Below under the same conditions to composite oxides adsorbent of the present invention in embodiment 3, be purchased nanoscale CaO adsorbent and carry out performance comparison test from the natural micron order CaO adsorbent of limestone, test result is as shown in Figure 4.
As can be seen from Figure 4, the adsorption capacity of nanoscale CaO adsorbent and natural micron order CaO adsorbent is continuous decrease in front 18 adsorption-desorption cyclic processes, although and composite oxides adsorbent of the present invention adsorption capacity in front 8 cyclic processes declines a little to some extent, but in cyclic process, go up gradually afterwards, even exceed the adsorption capacity of nanoscale CaO adsorbent.Can find out by contrast, the adsorption capacity of composite oxides adsorbent of the present invention is up to 55wt%, and demonstrates good cycle thermal stability.
Fig. 5 is the defined layered double-hydroxide Ca of the present invention 1-xal x(OH) 2(CO 3) x/2(LDH) XRD figure.Work as can be seen from Figure 5 Ca 1-xal x(OH) 2(CO 3) x/2x value while being 0.2-0.33, its structure is layered double-hydroxide (LDH) structure, and along with x value increases, the architectural feature peak of layered double-hydroxide (LDH) becomes more and more stronger, it is more and more perfect that layered double-hydroxide structure also becomes.
Fig. 6 is the layered double-hydroxide Ca shown in Fig. 5 1-xal x(OH) 2(CO 3) x/2(LDH) the XRD figure of the composite oxides adsorbent obtaining after calcining.As can be seen from Figure 6, principal crystalline phase is CaCO 3and CaO, wherein Al exists with amorphous alundum (Al2O3) form, and amorphous alundum (Al2O3) high degree of dispersion, around CaO crystal grain, plays the effect of growing up while stoping the calcining of CaO crystal grain.
Carrying out above-mentioned thermogravimetric analyzer (TGA) test and CO 2before adsorption-desorption circulation, the sample in Fig. 6 first (is used to N through 700 ℃ of pretreatment 2purge), make CaCO 3resolve into CaO.Because sample can ingress of air, CaO at room temperature will with airborne CO 2reaction generates CaCO 3, consider CO in air 2meeting and composite oxides sorbent reactions of the present invention, so principal crystalline phase is CaCO after above-mentioned layered double-hydroxide (LDH) calcining 3and CaO, do not require it to be sintered into CaO completely, therefore before adsorption-desorption circulation, add this step of pretreatment.
Fig. 7 has provided composite oxides adsorbent of the present invention and existing high temperature CO 2the adsorption capacity contrast schematic diagram of adsorbent.As can be seen from Figure 7, current existing high temperature CO 2the adsorption capacity of adsorbent all reduces gradually with the increase of adsorption-desorption cycle-index, and the adsorption capacity of composite oxides adsorbent of the present invention is more stable with the increase of adsorption-desorption cycle-index, although while just beginning the adsorption capacity of composite oxides adsorbent of the present invention a little less than some existing high temperature CO 2adsorbent, but after more than 10 circulations, the adsorption capacity of composite oxides adsorbent of the present invention is all higher than existing high temperature CO 2the adsorption capacity of adsorbent, composite oxides adsorbent of the present invention is remaining adsorption capacity more than 50wt% after the circulation of 200 multiple adsorb-desorption.
Can find out from above instantiation, adopt composite oxides adsorbent of the present invention to reach following technique effect:
1, the present invention is for absorption high temperature CO 2composite oxides adsorbent be particularly suitable for higher than 300 ℃, for example, under the environment of 500 ℃～700 ℃ to CO 2absorption, catch and remove, it can be used in mixed airflow that the various chemical reactions such as methanation, water-gas and methane reforming produce CO 2original position remove.
2, due to mutual-through type (1) [(M1 1-y, M2 y) 1-xm3 x(OH) 2] A n- x/nmH 2two or three hydroxide of stratiform that O represents have carried out appropriate calcining, compared with the composite oxides adsorbent obtaining or three hydroxide two with stratiform, and centering high temperature CO 2absorption property greatly improved, its adsorption capacity can be up to more than 55 % by weight.
3, composite oxides adsorbent of the present invention, compared with existing natural or synthetic adsorbent, for example CaO adsorbent, has better adsorption dynamics adsorption kinetics characteristic and cycle thermal stability.
The term that this description is used and form of presentation are only used as descriptive and nonrestrictive term and form of presentation, in the time using these terms and form of presentation, are not intended to any equivalent exclusion of the feature representing and describe or its part.
Although represented and described several embodiment of the present invention, the present invention is not restricted to described embodiment.On the contrary, those of ordinary skills should recognize in the situation that not departing from principle of the present invention and essence, can carry out any accommodation and improvement to these embodiments, and protection domain of the present invention is determined by appended claim and equivalent thereof.

Claims (16)

  1. One kind for absorption high temperature CO 2composite oxides adsorbent, it comprise or three hydroxide (LDH) dehydration two by stratiform and composite oxides, layered two or three hydroxide have following general formula (1):
    [(M1 1-yM2y) 1-xM3 x(OH) 2]A n- x/n·mH 2O （1）
    Wherein, M1 is Ca; M2 is the mixture of any or they in Mg, Sr, Mn, Fe, Co, Ni, Cu and Zn; M3 is the mixture of any or they in Al, Cr, Mn, Fe, La, Ce, Ga and In, A n-for CO 3 2-, Cl -, SO 4 2-, NO 3 -, OH -and ClO 4 -in the mixture of any or they; 0<x≤1.0; 0≤y<0.5; 0≤m≤8.
  2. 2. adsorbent according to claim 1, it also comprises the alkali carbonate or the alkali metal oxide that represent with following general formula (2):
    M4 2cO 3, M4HCO 3or M4 2o (2)
    Wherein, M4 is the mixture of any or they in Li, Na, K, Ru, Cs, and the mol ratios of the stratiform that the alkali carbonate that general formula (2) represents or alkali metal oxide and general formula (1) represent pair or three hydroxide are 0-0.2.
  3. 3. adsorbent according to claim 2, wherein, 0<y≤0.1.
  4. 4. adsorbent according to claim 2, wherein, M4 is Li, Na, K or their mixture.
  5. 5. according to one of any described adsorbent of claim 1-4, wherein, M2 is Mg; M3 is Al.
  6. 6. according to one of any described adsorbent of claim 1-4, wherein, layered general molecular formula two or three hydroxide are: Ca 1-xal x(OH) 2(CO 3) x/2; Wherein 0.1≤x≤0.35.
  7. 7. according to one of any described adsorbent of claim 1-4, wherein, layered two or three hydroxide dehydration refers to that thermal dehydration, mode comprise calcining, heating using microwave, infrared heating.
  8. 8. according to one of any described adsorbent of claim 1-4, wherein, described middle high temperature CO 2refer to CO 2temperature be greater than 300 ℃.
  9. 9. according to one of any described adsorbent of claim 1-4, wherein, described middle high temperature CO 2contain steam.
  10. One kind one of any described for absorption high temperature CO according to claim 1-9 2composite oxides absorbent preparation method, it comprises the following steps successively:
    (1) by coprecipitation, hydrothermal synthesis method, sol-gal process, two or three hydroxide of stratiform that deposition-precipitation method, infusion process, solid reaction process or the preparation of organic compound pyrolysismethod represent with general formula (1);
    (2) or three hydroxide two to the stratiform making in above-mentioned steps (1) carry out thermal dehydration, form composite oxides adsorbent after dehydration.
  11. 11. absorbent preparation methods according to claim 10, the mode of wherein said dehydration comprises calcining, heating using microwave, infrared heating.
  12. 12. absorbent preparation methods according to claim 10, wherein use alkali carbonate that general formula (2) represents or alkali metal oxide to add in layered two or three hydroxide preparation process, or add in the composite oxides that form after its dehydration.
  13. 13. absorbent preparation methods according to claim 10, wherein, prepare two or three hydroxide of stratiform by coprecipitation, by the mode of calcining, it are dewatered subsequently, and its process is as follows:
    (1) make M1 salting liquid, M2 salting liquid, M3 salting liquid and OH -aqueous slkali and/or CO 3 2-salting liquid, in the ratio co-precipitation in above-mentioned general formula (1), optionally carries out crystallization to coprecipitate subsequently, thereby makes two or three hydroxide of the stratiform representing with general formula (1);
    (2) the two or three hydroxide 1-10 hour of the stratiform that makes in calcining step (1) at 500-1100 ℃, obtain described composite oxides;
    (3) optionally, in above-mentioned steps (1) or after above-mentioned steps (2), in being 0-0.2 with layered mol ratios two or three hydroxide, ratio adds the alkali carbonate or the alkali metal oxide that represent with general formula (2).
  14. 14. absorbent preparation methods according to claim 13, wherein, described M1 salting liquid, M2 salting liquid and M3 salting liquid are nitrate; OH -aqueous slkali is LiOH, NaOH and/or KOH; CO 3 2-salting liquid is Na 2cO 3and/or (NH 4) 2cO 3.
  15. 15. absorbent preparation methods according to claim 14, comprising:
    (1) at 60～90 ℃ by the nitrate solution of M1, M2 and M3 and LiOH, NaOH and/or KOH solution and/or Na 2cO 3and/or (NH 4) 2cO 3the molar ratio that solution is pressed in general formula (1) mixes, and strong stirring 0.5～1.0 hour forms the liquid containing coprecipitate, and elimination liquid, obtains coprecipitate;
    (2) optionally, above-mentioned coprecipitate is inserted in reactor, make its crystallization 10-24 hour at 80-160 ℃;
    (3) repeat afterwards washing and filter, until pH value unchanged after, be dried, obtain two or three hydroxide of the stratiform representing with general formula (1);
    (4) the two or three hydroxide 1-10 hour of the stratiform that makes in calcining step (3) at 500-1100 ℃, obtain described composite oxides;
    (5) alkali carbonate or the alkali metal oxide that optionally, represent to the general formula (2) that to add with layered mol ratios two or three hydroxide in the composite oxides that obtain in above-mentioned steps (4) be 0-0.2; Or the alkali carbonate or the alkali metal oxide that in the coprecipitation process of above-mentioned steps (1), add the general formula (2) of above-mentioned quantity to represent.
  16. 16. absorbent preparation methods according to claim 15, wherein, M1 is Ca; M2 is Mg; M3 is Al; M4 is Li, Na, K or their mixture.
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CN105214597A (en) * 2015-09-21 2016-01-06 广东电网有限责任公司电力科学研究院 Middle temperature carbon-dioxide absorbent and forming method thereof
CN105289537A (en) * 2015-10-30 2016-02-03 广东电网有限责任公司电力科学研究院 Middle-temperature carbon dioxide solid absorbent and preparation method thereof
CN109475839A (en) * 2016-05-30 2019-03-15 艾斯希吉化工有限公司 Adsorbent for hydrocarbon purifying
CN108067180A (en) * 2018-01-11 2018-05-25 重庆大学 A kind of yttrium magnesium-calcium base CO2Adsorbent and preparation method thereof
CN108067180B (en) * 2018-01-11 2021-03-30 重庆大学 Yttrium magnesium-calcium based CO2Adsorbent and preparation method thereof
CN110227408A (en) * 2018-03-06 2019-09-13 黄华丽 A kind of preparation of carbon dioxide absorber and its purification method and device
CN108940185A (en) * 2018-07-31 2018-12-07 南京林业大学 A kind of magnetism quaternary Zn-Al-Fe-La houghite and its preparation method and application
CN111250099A (en) * 2020-03-31 2020-06-09 中国科学院过程工程研究所 Preparation method and application of composite metal oxide catalyst
CN115448310A (en) * 2022-09-23 2022-12-09 国网河北能源技术服务有限公司 Nitrogen-containing porous carbon material and preparation method and application thereof
CN115448310B (en) * 2022-09-23 2024-03-29 国网河北能源技术服务有限公司 Nitrogen-containing porous carbon material and preparation method and application thereof

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