CN111715274A - Used for desorbing CO in solution2Preparation method and application of heterogeneous catalyst - Google Patents

Abstract

The invention discloses a CO boiler belonging to industrial boiler and power plant₂Used for desorbing CO in solution in the technical field of trapping₂The preparation method and application of the heterogeneous catalyst. The heterogeneous catalyst is prepared by reacting SO₄ ^2‑The metal oxide is loaded on the HZSM-5 carrier; the method comprises the following specific steps: adding sulfate of metal oxide into water, adding HZSM-5 carrier, heating and stirring, cooling and filtering to obtain precipitate; washing, drying and roasting the precipitate to obtain the SO₄ ^2‑Metal oxide-HZSM-5 polypeptideA phase catalyst. The heterogeneous catalyst of the invention can promote absorption liquid to desorb CO₂Simultaneously improve the absorption liquid to CO₂The absorption performance of the catalyst is improved, and CO in the flue gas is captured under the condition of not adding a catalyst₂Compared with the process, the desorption rate is improved by 35 to 45 percent, the absorption efficiency is improved by 30 to 40 percent, the stability and the recycling performance are good, and the CO can be greatly reduced₂And (5) desorbing energy consumption.

Description

Used for desorbing CO in solution2Preparation method and application of heterogeneous catalyst

Technical Field

The invention belongs to industrial boiler and power plant CO₂The technical field of trapping, in particular to a method for desorbing CO in solution₂The preparation method and application of the heterogeneous catalyst.

Background

China's energy structure is mainly coal, and a large amount of CO is discharged after coal burning₂Causing a greenhouse effect and consequent extreme climate. As CO₂Maximum emission source, CO of electric power production₂62.66% of the total source, and therefore, CO is controlled₂From an emissions point of view, it is first necessary to control the CO emitted during the production of electricity₂. CO applied to coal-fired power plant₂There are three main technical routes for trapping, which are divided into: post-combustion capture, pre-combustion capture and oxygen-enriched combustion. Post combustion CO for a large number of existing power plants₂The trapping technology has good inheritance to the original equipment and becomes one of the main selectable routes for reducing the emission of greenhouse gases. The post-combustion trapping system is positioned at the downstream of various pollutant removing devices of the existing power plant and utilizes alcohol amine alkaline absorbent and CO in the flue gas₂Contact and generate chemical reaction to form unstable salt; under certain conditions, the salts are reversely decomposed to release CO₂Regenerating the absorption capacity of the absorbent to thereby convert CO₂The absorbent is desorbed and enriched from the flue gas, is convenient to use or store, and simultaneously, the absorbent can be recycled. Although the chemical absorption method has the characteristics of high decarburization efficiency, simple process, superior removal cost compared with other technologies, and the like, the amine-based solution absorption method also has the inherent defects that: the high heat of reaction leads to increased cooling costs; high regeneration energy consumption causes the maximum low pressure steam flow demand and the size change of the regeneration tower; large packed absorption columns are required to provide sufficient mass transfer area for chemical reactions; high linear power loss caused by overcoming pressure loss in regeneration tower. The combination of the above factors leads to the absorption and the capture of CO by the amino solution₂Higher investment in the system, higher operating costs, wherein the decarbonization desorbs CO₂The energy consumption of the process is large, the investment and the operation cost of equipment can be improved by 70 percent, and therefore, the CO is reduced₂The problem of high regeneration energy consumption in the trapping process is beneficial to the large-scale application of the carbon trapping process in a coal-fired power plant.

Much research has been focused on the improvement of amine-based solution absorption systems, mainly aiming at developing new alcohol amine solutions and phase change solvents to reduce CO₂The trapping process has the problems of high energy consumption and low absorption and desorption rates. But due to conventional CO₂The desorption temperature is 100-150 ℃, and the large amount of gasification of water in the temperature range is the main energy consumption, so that CO is carried out at a lower temperature (lower than 100 ℃), and₂desorb and ensure faster CO₂The absorption and desorption rates can significantly improve current carbon capture processes.

Disclosure of Invention

In order to solve the problems, the invention provides a method for desorbing CO in liquid₂The heterogeneous catalyst of (1) is prepared by reacting SO₄ ^2-/ZrO₂Loaded on HZSM-5 carrier;

the method comprises the following specific steps:

1) zr (SO)₄)₂·4H₂Adding O into water, adding an HZSM-5 carrier, heating and stirring, cooling and filtering to obtain a precipitate;

2) washing, drying and roasting the precipitate to obtain the SO₄ ^2-/ZrO₂-HZSM-5 heterogeneous catalyst;

the heterogeneous catalyst can desorb CO in liquid₂。

The heterogeneous catalyst can also improve CO absorption of absorption liquid₂The absorption efficiency of (2).

The desorption efficiency is 9-12.24 mmol/min.

Zr (SO) in the step 1)₄)₂·4H₂The mass ratio of O to the carrier is 1: 1-10, preparation of SO₄ ^2-/ZrO₂ZrO in-HZSM-5₂The content is 0.24-3.08 wt.%.

The heating temperature in the step 1) is 80-90 ℃, and the stirring time is 24-48 h.

In the step 2), the drying temperature is 110-.

Application of heterogeneous catalyst, wherein the heterogeneous catalyst is loaded on a substrate to obtain a loaded catalyst for CO₂Desorption of CO from liquids in a desorber₂Or improving CO absorption of the absorption liquid₂The absorption properties of (1).

Assembling the supported catalyst into catalyst modules, and arranging the catalyst modules at intervals along the height direction of the tower to obtain CO₂An absorption tower.

In CO₂A stirrer is arranged below the catalyst module in the desorption tower to obtain CO₂A desorption tower.

CO₂From CO₂The absorption liquid enters from the bottom of the absorption tower and flows into the absorption tower from CO₂The absorption tower flows into the top of the absorption tower and reversely contacts with the absorption tower to react under the action of the catalyst module to make CO react₂Absorbed by the absorption liquid; clean flue gas from CO₂High load of CO discharged from the top of the absorption column₂The rich solution passes through a lean-rich solution heat exchanger to be treated from CO₂The top of the desorption tower flows in; CO 2₂The rich solution is uniformly mixed in the desorption tower by a stirrer to react with the catalyst, so that CO is generated₂Desorption and removal of CO₂And discharging from the top of the desorption tower.

The invention has the beneficial effects that:

1. the invention synthesizes a heterogeneous solid phase catalyst material (SO) with simple preparation process₄ ^2-/ZrO₂-HZSM-5), with the conventional solid acid metal oxide Al₂O₃Compared with the desorption performance of ZnO and the like as the catalyst, the catalyst has good recycling performance, can be recycled for at least 4 times, and still has good catalytic performance.

2. The process for desorbing and regenerating carbon dioxide in the absorption liquid by heterogeneous catalysis can reduce the carbon capture processThe desorption energy consumption of the method can be used for absorbing CO in solution by various amino groups₂Thereby promoting the wide popularization of the CCS technology and reducing CO₂And (5) discharging.

3. The invention can realize CO at low temperature (below 100 ℃) by adding the catalyst₂Compared with non-catalysis, the regeneration method has the advantages that the desorption energy consumption is reduced, and the desorption efficiency can reach 55-70% below 100 ℃. The solid phase catalyst material has good desorption performance and high recovery utilization rate, and can reduce CO by combining the desorption process provided by the invention₂The energy consumption is desorbed, the operation cost of the prior art is reduced, the existing coal-fired power plant process is hopefully improved, and the low-carbon emission is realized. .

4. The desorption rate of the catalyst is 9-12.24 mmol/min; CO compared with no catalyst₂The desorption amount is improved by 20-40%, and the desorption rate is improved by 35-45%.

5. The heterogeneous catalyst of the invention can promote absorption liquid to desorb CO₂Simultaneously improve the absorption liquid to CO₂The absorption performance of the catalyst is improved, and CO in the flue gas is captured under the condition of not adding a catalyst₂Compared with the process, the absorption efficiency is improved by 30-40%.

6. The method uses the low-cost HZSM-5 molecular sieve as the carrier to synthesize the SZ @ H-1/4 catalyst in one step, avoids the complex process of multi-step synthesis, greatly saves the preparation cost of the catalyst, and is beneficial to the industrial application of the catalyst.

Drawings

FIG. 1 is an XRD pattern of the prepared catalyst;

FIG. 2 is SEM and TEM images of HZSM-5 and 1/4 scaled catalysts;

FIG. 3 shows NH of HZSM-5 and different ratios of SZ @ H catalyst₃-TPD and Py-IR diagram;

FIG. 4 is a diagram showing desorption of CO₂A quantity and rate performance map;

FIG. 5 is a diagram of the recycling performance of SZ @ H-1/4;

FIG. 6 shows that SZ @ H-1/4 absorbs CO in absorption liquid₂The impact of performance;

FIG. 7 is a graph comparing the catalytic performance of the prepared catalyst with other common solid acid catalysts;

FIG. 8 is a process flow diagram of the catalytic desorption of carbon dioxide from the carbon capture process absorption liquid.

Wherein:

1，CO₂an absorption tower; 2, a lean-rich liquid heat exchanger; 3, CO₂A desorption tower; 4, a catalyst module; 5, a stirrer; 6, a pump; 7, rich liquid; 8, barren liquor; 9, refluxing liquid; 10, smoke gas; 11, cleaning the flue gas; 12, CO₂。

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

example 1

SO₄ ^2-/ZrO₂-HZSM-5 catalyst preparation scheme: by ion exchange using Zr (SO)₄)₂·4H₂Performing ion exchange on O and HZSM-5 to synthesize catalysts SO with different zirconia contents₄ ^2-/ZrO₂-HZSM-5。

20g of Zr (SO)₄)₂·4H₂Dissolving O in 400mL deionized water, stirring uniformly, adding 14g, 28 g and 56g of HZSM-5 into the solution respectively, stirring the obtained solution for 24-48h at 80-90 ℃, cooling to room temperature, centrifugally washing the obtained precipitate for 5 times by using the deionized water, drying for 12-24h at 110-130 ℃, and finally roasting for 4-6h at 500-600 ℃, wherein the heating rate is 5 ℃/min, SO as to obtain SO₄ ^2-/ZrO₂-HZSM-5 white powder. Prepared SO₄ ^2-/ZrO₂-HZSM-5 heterogeneous catalyst material, in which ZrO is theoretically calculated₂A mass of 7g, preparation of theoretically calculated ZrO₂And SO of three different zirconia contents of 1/2, 1/4 and 1/8 in HZSM-5 mass ratio respectively₄ ^2-/ZrO₂-HZSM-5。

Example 2

Simulating the actual decarburization process to construct and utilize SO₄ ^2-/ZrO₂-HZSM-5 heterogeneous catalysis desorption carbon capture process absorption liquid CO₂The process scheme is shown in figure 8, and the process flow is as follows：

Takes a stainless steel sieve plate as a base material, and a heterogeneous catalyst SO is loaded on the surface of the stainless steel sieve plate₄ ^2-/ZrO₂HZSM-5, obtaining a slab catalyst, treating the slab catalyst to assemble catalyst modules 4 from the slab catalyst units, arranging a plurality of catalyst modules 4 at intervals along the height of the column, and using the structure CO₂The absorption tower is used for decarbonization.

A plurality of catalyst modules 4 are arranged at intervals along the height direction of the tower, and a plurality of non-interfering stirrers 5 are arranged below each layer of catalyst module 4 to obtain CO₂A desorber structure.

Containing CO₂From CO 10₂The absorption liquid enters from the bottom of the absorption tower 1 and flows into the absorption tower from the CO₂The gas flows into the top 1 of the absorption tower and reversely contacts with the flue gas 10, and fully reacts under the catalytic action of the heterogeneous catalyst. CO in flue gas₂Absorbed by absorption liquid to remove CO₂From CO in the clean flue gas 11₂The overhead of the absorption column 1 is discharged. The high-load rich liquid 7 flows out of the absorption tower and flows into CO through the lean rich liquid heat exchanger 2₂The desorption tower 3 performs desorption. CO 2₂The rich solution 7 is uniformly mixed by the stirrer 5 in the desorption tower to be fully contacted with the catalyst, and the rich solution 7 is subjected to desorption reaction to release CO through catalysis₂. Carbon dioxide 12 from CO₂After being discharged from the top of the desorption column 3, the waste water can be collected and reused. After desorption is completed, the rich liquid 7 with high load is converted into lean liquid 8 with low load, and a part of the lean liquid 8 with low load is returned to CO again as reflux liquid 9 through the pump 6₂The desorption tower 3 participates in the reaction to improve CO₂Desorption rate, another part of lean solution 8 is put into CO after heat exchange₂The absorption tower is reused.

Example 3

Theoretical calculated ZrO prepared in example 1₂And SO of three different zirconia contents of 1/2, 1/4 and 1/8 in HZSM-5 mass ratio respectively₄ ^2-/ZrO₂-HZSM-5, named SZ @ H-1/2, SZ @ H-1/4 and SZ @ H-1/8, respectively. The strain is characterized, and the structural information of the strain is researched. ICP data (Table 1) XRD (FIG. 1), SEM and TEM (FIGS. 2a and 2b), and NH₃The prepared catalyst was determined by the following-TPD and Py-IR spectra (FIGS. 3a and 3b)In agent ZrO₂The content is 0.24-3.08 wt.%, and SO₄ ^2-/ZrO₂Uniformly dispersed on the surface of the catalyst to form uniformly dispersed active sites, wherein ZrO₂The acid is the most acidic at a content of 3.08 wt.%, with the most active site.

Table 1 shows the ICP and XRF results for three catalysts, when ZrO₂And HZSM-5 at 1/4 mass ratio to obtain catalyst ZrO₂And sulfate content is the largest, therefore 1/4 is the best preparation ratio, actually measured ZrO₂The content was 3.08 wt%.

TABLE 1 ICP and XRF results

As shown in FIG. 1, with different ZrO₂The loaded SZ @ H catalyst exhibited the same spectral trend over the typical 2 theta range. All SZ @ H catalysts showed characteristic diffraction peaks corresponding to the MFI topology of HZSM-5. ZrO not observed in SZ @ H catalyst₂This shows the catalyst, ZrO, prepared using an ion exchange process₂Mainly in the form of amorphous phase or well dispersed nanocrystals, on the surface of HZSM-5, even penetrating into the channels of HZSM-5.

Comparing HZSM-5 and SZ @ H-1/4 catalysts according to fig. 2a and fig. 2b, both crystals exhibited typical ZSM-5 molecular sieve cubic crystal morphology. No change in morphology was observed after the exchange process and no lattice information for the bulk material was observed in the HRTEM images. The results show that ZrO₂The species enter the molecular sieve framework through ion exchange, the original structure of the species is not damaged, and simultaneously a large amount of active ZrO is introduced₂Species of the species.

FIG. 3a indicates the NH of all catalysts₃The TPD curve shows two desorption peaks at 200-500 ℃ indicating that the catalyst has both weaker and stronger surface acid sites. However, the new peaks were found at 690 ℃ and 750 ℃ for the SZ @ H-1/4 catalyst and 690 ℃ for the SZ @ H-1/2 catalyst, indicating ZrO in the SZ @ H-1/4 catalyst₂And the more the sulfate radical content,the more strong acid sites. FIG. 3B shows ion exchange, introducing a large number of protonic acid sites (B acids). Thus, ZrO was used in comparison with HZSM-5 alone₂And sulfate modified HZSM-5 can increase its total acid sites. The enhancement of acidity can make the catalyst desorb CO₂More protonic acid and electron acid are provided, thereby destroying carbamate and promoting CO₂Regenerating and improving desorption temperature. The more acidic, the faster the desorption rate.

Example 4

Study of HZSM-5 with three SO's of different zirconium content₄ ^2-/ZrO₂-HZSM-5 desorption of CO in MEA rich solution₂Catalytic performance in (fig. 4). The results show that the prepared catalyst can improve the desorption rate and promote CO₂Compared with non-catalysis, the desorption energy consumption is reduced, and the desorption efficiency can reach 70 percent at 98 ℃.

The prepared SZ @ H catalyst with different zirconium contents can obviously improve CO of the absorption liquid₂Desorption performance. Among them, the SZ @ H-1/4 catalyst has the best catalytic performance due to its abundant acid sites. CO thereof₂The catalytic desorption amount is 371mmol when 120min, and the maximum desorption rate is 12.24 mmol/min; compared with the method without adding the catalyst, the desorption amount is improved by 40 percent, and the desorption rate is improved by about 37 percent.

Example 5

The SZ @ H-1/4 catalyst of example 3 was selected and its operating stability was investigated. FIG. 5 shows that SZ @ H-1/4 has good recycling performance, and still has good catalytic performance after 4 cycles of absorption desorption catalytic experiments, which is 1.25 times of non-catalytic efficiency.

Example 6

Selecting an SZ @ H-1/4 catalyst, and studying CO absorption of absorption liquid by the catalyst at 40 DEG C₂The influence of (c). FIG. 6 shows that SZ @ H-1/4 can not only promote absorption liquid to desorb CO₂Simultaneously improve the absorption liquid to CO₂The absorption properties of (1). Under the conditions of no catalyst and addition of SZ @ H-1/4 catalyst, CO in flue gas is effectively captured₂(C/C₀<The absorption periods of 0.1) were 33min and 45min, respectively. Therefore, the addition of the catalyst can improve the absorption efficiency by 36%.

As can be seen from FIG. 7, compared with the common solid acid catalyst, the SZ @ H-1/4 catalyst prepared by the invention can realize CO desorption at low temperature of 98 DEG C₂Thereby avoiding the gasification of water and reducing the desorption energy consumption by 31 percent. Application of solid acid material as catalyst to CO₂During desorption, the material promotes CO by providing a protic acid (B acid) and an electronic acid (L acid) to destroy the carbamate₂And (4) regenerating. The heterogeneous catalyst prepared by the invention can realize good CO at the low temperature of 98 ℃ and below₂Desorption is carried out, thereby avoiding the gasification of water and greatly reducing the regeneration energy consumption.

Claims (10)

1. Used for desorbing CO in liquid₂The heterogeneous catalyst of (1) is prepared by reacting SO₄ ^2-/ZrO₂Loaded on HZSM-5 carrier;

the method comprises the following specific steps:

1) zr (SO)₄)₂·4H₂Adding O into water, adding an HZSM-5 carrier, heating and stirring, cooling and filtering to obtain a precipitate;

2) washing, drying and roasting the precipitate to obtain the SO₄ ^2-/ZrO₂-HZSM-5 heterogeneous catalyst;

the heterogeneous catalyst can desorb CO in liquid₂。

2. The method of claim 1, wherein the heterogeneous catalyst further enhances CO uptake by the absorption liquid₂The absorption efficiency of (2).

3. The method of claim 1, wherein the desorption efficiency is 9 to 12.24 mmol/min.

4. The method of claim 1, wherein Zr (SO) is added in step 1)₄)₂·4H₂The mass ratio of O to the carrier is 1: 1-10.

5. The method of claim 1, wherein the heating temperature in step 1) is 80-90 ℃ and the stirring time is 24-48 h.

6. The method as claimed in claim 1, wherein the drying temperature in step 2) is 110-.

7. Use of a heterogeneous catalyst prepared according to any of the claims 1-6, characterized in that the heterogeneous catalyst is supported on a substrate to obtain a supported catalyst for CO₂Desorption of CO from liquids in a desorber₂Or improving CO absorption of the absorption liquid₂The absorption properties of (1).

8. Use according to claim 7, wherein the supported catalyst is assembled into catalyst modules, the catalyst modules being arranged at intervals along the height of the column to obtain CO₂An absorption tower.

9. Use according to claim 8, characterised in that the CO is present₂A stirrer is arranged below the catalyst module in the desorption tower to obtain CO₂A desorption tower.

10. Use according to claim 8 or 9, wherein CO is₂From CO₂The absorption liquid enters from the bottom of the absorption tower and flows into the absorption tower from CO₂The absorption tower flows into the top of the absorption tower and reversely contacts with the absorption tower to react under the action of the catalyst module to make CO react₂Absorbed by the absorption liquid; clean flue gas from CO₂High load of CO discharged from the top of the absorption column₂The rich solution passes through a lean-rich solution heat exchanger to be treated from CO₂The top of the desorption tower flows in; CO 2₂The rich solution is uniformly mixed in the desorption tower by a stirrer to react with the catalyst, so that CO is generated₂Desorption and removal of CO₂And discharging from the top of the desorption tower.

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