LOW ENERGY CONSUMPTION ANHYDROUS CO2 PHASE CHANGE ABSORPTION AGENT, AND REGENERATION METHOD AND APPLICATION THEREOF

Abstract

Disclosed in the present invention are a low energy consumption anhydrous CO.sub.2 phase change absorption agent, and a regeneration method and an application thereof, the absorption agent using a unitary diamine with a primary amine (NH.sub.2—) and a tertiary amine (—N—), and not containing any other organic solvent, water, and ionic liquid; two alkyl branches are linked to a nitrogen atom of the tertiary amine, forming a certain hydrophobicity; after absorbing the CO.sub.2, the diamine changes from a liquid phase to a solid phase, undergoing liquid-solid phase change to form white amino formate crystals.

Claims

1. An application of a low-energy anhydrous CO.sub.2 phase change absorbent, including: mixing the phase change absorbent with a chemical reaction tail gas, a combustion flue gas, a natural gas mixture, an urban gas, a natural gas, or a combination thereof, wherein the phase change absorbent absorbs CO.sub.2 from the chemical reaction tail gas, the combustion flue gas, the natural gas mixture, the urban gas, the natural gas, or the combination thereof and undergoes a liquid-solid phase transformation, wherein a temperature in the liquid-solid phase transformation is 45-60° C., wherein the phase change absorbent is a diamine compound having both primary amine (NH.sub.2—) and tertiary amine (—N—) at a concentration of 100%, free of any other organic solvents, water and ionic liquids, wherein the tertiary amine nitrogen atom has two alkyl branches linked to it, and its molecular structure formula is shown in formula I: ##STR00017## among them, R.sub.1 and R.sub.2 are C1—C4 alkyl chains, R.sub.3 is —CH.sub.2—CH.sub.2—, and the diamine compound is selected from the group consisting of: N,N-dimethylethylenediamine, R.sub.1 and R.sub.2 are CH.sub.3—, and R.sub.3 is —CH.sub.2—CH.sub.2—; N,N-diethylethylenediamine, R.sub.1 and R.sub.2 are CH.sub.3—CH.sub.2—, and R.sub.3 is —CH.sub.2—CH.sub.2—; N,N-diisopropylethylenediamine, R.sub.1 and R.sub.2 are CH.sub.3—CH(CH.sub.3)—, and R.sub.3 is —CH.sub.2—CH.sub.2—; and N,N-di-n-butylethylenediamine, R.sub.1 and R2 are CH.sub.3—CH.sub.2—CH.sub.2—CH.sub.2—, and R.sub.3 is —CH.sub.2—CH.sub.2—, wherein a mechanism of the liquid-solid phase transformation is: R.sub.1R.sub.2NR.sub.3NH.sub.2+CO.sub.2R.sub.1R.sub.2NR.sub.3NH.sub.2.sup.+COO.sup.− R.sub.1R.sub.2NR.sub.3NH.sub.2+R.sub.1R.sub.2NR.sub.3NH.sub.2.sup.+COO.sup.−R.sub.1R.sub.2NR.sub.3NH.sub.3.sup.++R.sub.1R.sub.2NR.sub.3NHCOO.sup.−, wherein when the phase change absorbent absorbs CO.sub.2, a flow rate of CO.sub.2 is 20-40 ml/min, an absorption saturation is achieved in 8-15 min, and a CO.sub.2 loading of the absorbent is 0.400-0.499 mol CO.sub.2/mol amine, wherein the phase change absorbent undergoes the liquid-solid phase transformation after absorbing CO.sub.2, and a solid phase white carbamate crystal is directly formed from a liquid phase.

2. The application of the low-energy CO.sub.2 phase change absorbent according to claim 1, wherein the phase change absorbent is an anhydrous single absorbent, and there is no excess liquid after absorbing CO.sub.2.

3. The application of the low-energy CO.sub.2 phase change absorbent according to claim 1, wherein an absorption load of the phase change absorbent at 50° C. is higher than that at 30° C. by 0.01-0.02 mol CO.sub.2/mol amine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows the real-time appearance of CO.sub.2 absorption by N,N-Dimethylaminoethylamine as absorbent.

[0035] FIG. 2 is a dynamic absorption process diagram of CO.sub.2 absorption capacity and CO.sub.2 absorption rate using N,N-Dimethylaminoethylamine as absorbent at 30-50° C.

DESCRIPTION OF THE EMBODIMENTS

[0036] The present disclosure is illustrated by the following examples, but the present disclosure is not limited to the following embodiments. The change implementation is included in the technical scope of the present disclosure without departing from the scope of purposes described before and after.

Example 1

[0037] The absorbent of the disclosure adopts a single diamine compound N,N′-diethyl ethylenediamine with both primary amine (NH2—) and tertiary amine (N—) at a concentration of 100%, without any other organic solvent, water and ionic liquids, wherein the tertiary amine nitrogen atom is linked with two alkyl branchs to form a certain hydrophobicity and its

[0038] molecular structure formula:

##STR00009##

When the absorbent which is N,N′-diethyl ethylenediamine absorbs CO.sub.2, the flow rate of CO.sub.2 is 25 ml/min, and the absorption saturation is achieved in 10 minutes. The CO.sub.2 loading of the absorbent is 0.465 mol CO.sub.2/mol amine. The phase transformation reaction mechanism of the absorbent is as follows:

##STR00010##

[0039] The disclosure provides a regeneration method of a low energy consumption anhydrous CO.sub.2 phase change absorbent, which comprises the following steps: [0040] 1) Sealed sampling: take 2.80 g of the absorbent, the absorbent then absorbs CO.sub.2 to transform into carbamate solid, and put it into a 20 ml glass reactor for sealing; [0041] 2) Phase change regeneration: put the glass reactor in the oil bath, control the temperature of the oil bath to 100 ° C., introduce N.sub.2, and the rate is 30 ml/min; [0042] 3) Regeneration calculation: heating the glass reactor for 45 min, taking it out, sealing it, weighing it and calculating it, the CO.sub.2 release amount is 0.370 mol CO.sub.2/mol amine, and the regeneration efficiency is 79.57%; [0043] 4) Phase change absorption: place that regenerated glass reactor contain diamine solution in a 25° C. water bath, introducing CO.sub.2 at a rate of 25 ml/min; [0044] 5) Absorption calculation: take out the glass reactor after 45 min of phase change reaction, seal it, weigh it, calculate it, CO.sub.2 absorption is 0.368 mol CO.sub.2/mol amine; [0045] 6) Cyclical implementation: repeat the above regeneration step and absorption step for 4 times, the regeneration efficiency of diamine is 77.20%, and the CO.sub.2 absorption amount is 0.359 mol CO.sub.2/mol.

[0046] The absorbent of the disclosure is applied to recover CO.sub.2 from various chemical reaction tail gases.

Example 2

[0047] The absorbent of the disclosure adopts a single diamine compound N,N′-diethyl ethylenediamine with both primary amine (NH2—) and tertiary amine (N—) at a concentration of 100%, without any other organic solvent, water and ionic liquids, wherein the tertiary amine nitrogen atom is linked with two alkyl branchs to form a certain hydrophobicity and its molecular structure formula:

##STR00011##

When the absorbent N,N′-diethyl ethylenediamine absorbs CO.sub.2, the flow rate of CO.sub.2 is 30 ml/min, and the absorption saturation is achieved in 12 minutes. The CO.sub.2 loading of the absorbent is 0.464 mol CO.sub.2/mol amine. The phase transformation reaction mechanism of the absorbent is as follows:

##STR00012##

[0048] The disclosure provides a regeneration method of a low energy consumption anhydrous CO.sub.2 phase change absorbent, which comprises the following steps: [0049] 1) Sealed sampling: Take 3.10 g of the absorbent, the absorbent then absorbs CO.sub.2 to transform into carbamate solid, and put it into a 20 ml glass reactor for sealing; [0050] 2) Phase change regeneration: put the glass reactor in the oil bath, control the oil bath temperature to 105° C., pass into N.sub.2, the rate is 35 ml/min; [0051] 3) Regeneration calculation: heating the glass reactor for 50 min, taking it out, sealing it, weighing it, and calculating it, the CO.sub.2 release amount is 0.368 mol CO.sub.2/mol amine, and the regeneration efficiency is 78.66%; [0052] 4) Phase change absorption: place the regenerated glass reactor containing the diamine solution in a 30° C. water bath and pass CO.sub.2 at a rate of 30ml/min; [0053] 5) Absorption calculation: take out the glass reactor after the phase change reaction for 50 min, seal it, weigh it, and calculate it. The CO.sub.2 absorption capacity is 0.364 mol CO.sub.2/mol amine; [0054] 6) Cyclical implementation: repeat the above regeneration and absorption steps four times, the regeneration efficiency of binary amine is 76.72%, and the CO.sub.2 absorption amount is 0.356 mol CO.sub.2/mol.

[0055] The absorbent of the disclosure is applied to recover CO.sub.2 in combustion flue gas.

Example 3

[0056] The absorbent of the disclosure adopts a single diamine compound N,N′-diethyl ethylenediamine with both primary amine (NH.sub.2—) and tertiary amine (N—) at a concentration of 100%, without any other organic solvent, water and ionic liquids, wherein the tertiary amine nitrogen atom is linked with two alkyl branchs to form a certain hydrophobicity and its

[0057] molecular structure formula:

##STR00013##

When the absorbent N,N′-diethyl ethylenediamine absorbs CO.sub.2, the flow rate of CO.sub.2 is 35 ml/min, and the absorption saturation is achieved in 9 minutes. The CO.sub.2 loading of the absorbent is 0.413 mol CO.sub.2/mol amine. The phase transformation reaction mechanism of the absorbent is as follows:

##STR00014##

[0058] The disclosure provides a regeneration method of a low energy consumption anhydrous CO.sub.2 phase change absorbent, which comprises the following steps: [0059] 1) Sealed sampling: take 3.30 g of the absorbent, the absorbent then absorbs CO.sub.2 to transform into carbamate solid, and put it into a 20 ml glass reactor for sealing; [0060] 2) Phase change regeneration: put the glass reactor in the oil bath, control the oil bath temperature to 110° C., pass into N.sub.2, the rate is 33 ml/min; [0061] 3) Regeneration calculation: heating the glass reactor for 55 min, taking it out, sealing it, weighing it, and calculating it, the CO.sub.2 release amount is 0.341 mol CO.sub.2/ mol amine, and the regeneration efficiency is 82.57%; [0062] 4) Phase change absorption: Place the regenerated glass reactor containing the diamine solution in a 35° C. water bath and pass CO.sub.2 at a rate of 35 ml/min; [0063] 5) Absorption calculation: take out the glass reactor after the phase change reaction for 55 min, seal it, weigh it, and calculate it. The CO.sub.2 absorption capacity is 0.339 mol CO.sub.2/mol amine. [0064] 6) Cyclical implementation: repeat the above regeneration step and absorption step four times, the regeneration efficiency of binary amine is 80.39%, and the CO.sub.2 absorption amount is 0.332 mol CO.sub.2/mol.

[0065] The absorbent of the disclosure is applied to recover CO.sub.2 in natural mixed gas.

Example 4

[0066] The absorbent of the disclosure adopts a single diamine compound N,N′ -diethyl ethylenediamine with both primary amine (NH.sub.2—) and tertiary amine (N—) at a concentration of 100%, without any other organic solvent, water and ionic liquids, wherein the tertiary amine nitrogen atom is linked with two alkyl branchs to form a certain hydrophobicity and its molecular structure formula:

##STR00015##

When the absorbent N,N′-diethyl ethylenediamine absorbs CO.sub.2, the flow rate of CO.sub.2 is 32 ml/min, and the absorption saturation is achieved in 13 minutes. The CO.sub.2 loading of the absorbent is 0.493 mol CO.sub.2/mol amine. The phase transformation reaction mechanism of the absorbent is as follows:

##STR00016##

[0067] The disclosure provides a regeneration method of a low energy consumption anhydrous CO.sub.2 phase change absorbent, which comprises the following steps: [0068] 1) Sealed sampling: take 3.50 g of the absorbent, the absorbent then absorbs CO.sub.2 to transform into carbamate solid, and put it into a 20 ml glass reactor for sealing; [0069] 2) Phase change regeneration: put the glass reactor in the oil bath, control the oil bath temperature to 115° C., pass into N.sub.2, the rate is 40 ml/min; [0070] 3) Regeneration calculation: heating the glass reactor for 60 min, taking it out, sealing, weighing, and calculating, the CO.sub.2 release amount is 0.409 mol CO.sub.2/mol amine, and the regeneration efficiency is 82.96%; [0071] 4) Phase change absorption: place the regenerated glass reactor containing the diamine solution in a 40° C. water bath and pass CO.sub.2 at a rate of 32 ml/min; [0072] 5) Absorption calculation: take out the glass reactor after the phase change reaction for 52 min, seal it, weigh it, and calculate it. The CO.sub.2 absorption capacity is 0.390 mol CO.sub.2/mol amine. [0073] 6) Cyclical implementation: repeat the above regeneration step and absorption step four times, the regeneration efficiency of binary amine is 76.87%, and the CO.sub.2 absorption amount is 0.379 mol CO.sub.2/mol.

[0074] The absorbent of the disclosure is applied to remove CO.sub.2 from urban gas, natural gas, etc.

[0075] According to the above examples, the new CO.sub.2 phase change absorbent has the advantages of fast absorption rate, large absorption load, reduced phase separation process, high regeneration efficiency in a short time, water-free solvent, reduced latent heat of solvent, reduced energy consumption, and can be widely used to recover CO.sub.2 from various chemical reaction tail gas, combustion flue gas and natural mixed gas, and can also be used to remove CO.sub.2 from urban gas and natural gas.