Preparation method and application of carbon dioxide adsorbent particles with high desorption rate

Abstract

The invention discloses a preparation method and application of carbon dioxide adsorbent particles with high desorption rate. The preparation method comprises the following steps: ball-milling and uniformly mixing a silicon-based carrier, a binder and a heat-conducting additive; mixing the uniformly mixed powder with a polyvinyl alcohol solution, extruding and granulating, and calcining; and dipping the calcined particles in a modifier to obtain carbon dioxide adsorbent particles with high desorption rate, wherein the mass ratio of the silicon-based carrier to the binder to the heat-conducting additive is 100: (30-40): (1-10). According to the prepared adsorbent particles, by doping a proper amount of BN, the heat conductivity is improved by 29%, so that the desorption rate is improved, and the average desorption rate is improved by 42%. The prepared adsorbent particles with the high desorption rate are simple in production process, low in cost and good in adsorption performance.

Description

Technical Field

[0001] The invention belongs to the field of carbon dioxide adsorbent, and in particular relates to a preparation method of carbon dioxide adsorbent particles with a high desorption rate and application thereof. Background Art

[0002] The widespread use of fossil energy has led to a huge amount of carbon dioxide emissions, which is considered the main cause of global warming. At present, the world has also made a series of efforts, including reducing the use of fossil energy, developing efficient energy utilization devices, increasing the use of renewable energy, reducing carbon dioxide emissions in the atmosphere, etc. However, with the growth of the global population, the use of fossil fuels will continue to increase. In the next few decades, humans will still need to rely on fossil energy, so they are still facing huge pressure to reduce emissions. It is estimated that there will still be tens of billions of tons of carbon dioxide emissions each year. Therefore, CO2 capture is regarded by the Intergovernmental Panel on Climate Change as a necessary technology to curb the growth of CO2 concentrations.

[0003] Among the many carbon dioxide adsorbents, solid amine adsorbents have attracted widespread attention due to their high adsorption selectivity and high adsorption capacity. However, most of the current solid amine adsorbents are powders, which are difficult to apply to large-scale carbon dioxide capture due to the pressure drop problem during large-scale adsorption. For this reason, granulation technology for solid amine adsorbents is a necessary step. After granulation, the desorption rate and adsorption capacity usually decrease significantly, and a high desorption rate is of great significance to improving the overall capture efficiency of the system. Therefore, how to achieve high desorption rate and high adsorption capacity while granulating is a difficult problem that needs to be solved in carbon capture. Summary of the invention

[0004] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a method for preparing carbon dioxide adsorbent particles with a high desorption rate. Compared with non-optimized particles, the carbon dioxide adsorbent particles prepared by the present invention have almost unchanged adsorption capacity and significantly improved desorption rate, which effectively solves the problem that the desorption rate and adsorption capacity of existing solid amine adsorbents usually decrease significantly after granulation.

[0005] The present invention also provides the carbon dioxide adsorbent particles with a high desorption rate and applications thereof.

[0006] Technical solution: In order to achieve the above-mentioned purpose, the method for preparing carbon dioxide adsorbent particles with a high desorption rate of the present invention comprises the following steps:

[0007] The silicon-based carrier, the binder and the thermal conductive additive are evenly mixed by ball milling; the evenly mixed powder is mixed with the polyvinyl alcohol solution, extruded into granules, and then calcined; the calcined particles are immersed in a modifier to obtain carbon dioxide adsorbent particles with a high desorption rate.

[0008] Among them, the mass ratio of the silicon-based carrier, the binder, and the thermal conductivity additive is 100:30 - 40:1 - 10.

[0009] Preferably, the mass ratio of the silicon-based carrier, the binder, and the thermal conductivity additive is 100:30 - 40:5.

[0010] Among them, the silicon-based carrier is silica gel, and the thermal conductivity additive is boron nitride.

[0011] Among them, the binder includes the optional binder attapulgite or bentonite, and the fixed binder methylcellulose.

[0012] Among them, the mass ratio of the optional binder to the fixed binder is 3 - 4:4 - 3.

[0013] Preferably, the ball milling speed is 600 rpm, and the ball milling time is 2 - 4 h.

[0014] Among them, the mass ratio of the powder to polyvinyl alcohol is 1:1 - 2, the concentration of the polyvinyl alcohol solution is 2% - 5%, the diameter of the extruded product after extrusion is 1 - 2 mm, and the diameter of the granulated particles is 1 - 2 mm.

[0015] Among them, the temperature of the calcination is 500 - 600 °C, and the time is 10 - 15 h.

[0016] Furthermore, the heating rate during the calcination is 10 °C / min, the calcination temperature is 550 °C, and the calcination time is 12 h.

[0017] Among them, the amine group-containing impregnating modifier of the modifier is a polyethyleneimine (Mw ~ 800) solution, and the dosage ratio of the particles after calcination to the adsorbent is 500 mg:10 - 20 ml.

[0018] Preferably, the solvent of the polyvinyl alcohol solution is deionized water, and the solvent of the polyethyleneimine solution is anhydrous methanol or anhydrous ethanol.

[0019] The high-desorption-rate carbon dioxide adsorbent particles prepared by the preparation method of the high-desorption-rate carbon dioxide adsorbent particles of the present invention.

[0020] The application of the high-desorption-rate carbon dioxide adsorbent particles of the present invention in adsorbing carbon dioxide.

[0021] Furthermore, the specific steps for the present invention to measure the CO2 adsorption performance of the sample using a synchronous thermal analyzer are as follows:

[0022] (1) Pretreatment stage: Remove the skin of the crucible, weigh about 8 mg of the sample and put it into the crucible, introduce N2 at a flow rate of 100 ml / min, heat from room temperature to 100 °C at a heating rate of 10 °C / min, and keep it at 100 °C for 30 min to fully remove water, CO2 and other volatile gases in the adsorbent.

[0023] (2) Adsorption stage: Cool down the furnace to the adsorption temperature of 35 °C, switch to 15% CO2 (the rest is balanced with N2), and perform adsorption for 1 h to obtain the adsorption curve of the sample mass changing with time. If measuring the adsorption process under air conditions, then switch to air and keep it for 4 h.

[0024] (3) Desorption stage: Switch the atmosphere back to pure N2, heat from the adsorption temperature to 100 °C at a heating rate of 10 °C / min, and keep it at 100 °C for 30 min to complete the desorption process.

[0025] In the present invention, silica gel, attapulgite, methyl cellulose, and boron nitride are uniformly mixed, added with a polyvinyl alcohol solution, and made into particles; the carrier particles are calcined to obtain the silica-based carrier particles; the carrier particles are modified by amine impregnation. The adsorbent particles prepared by the present invention have a 29% increase in thermal conductivity by doping a specific proportion of BN, so the desorption rate is improved, and the average desorption rate is increased by 42%.

[0026] The present invention prepares a solid amine adsorbent particle, and the most important thing is the composition of the carrier particle. The present invention prepares carrier particles with higher thermal conductivity by regulating parameters such as the binder and thermal conductivity additive, and achieves a faster desorption rate after amine loading.

[0027] The present invention first improves the thermal conductivity of the solid amine adsorbent particle by adding BN. BN is thermally stable and does not react at a high temperature of 500 °C. By regulating the addition amount of the thermal conductivity additive and granulating by extrusion and rounding, carbon dioxide adsorbent particles with high thermal conductivity and high desorption rate are obtained. In addition, the addition amount of BN in the present invention is very important. Only under the specific addition amount of the present invention can the prepared carbon dioxide adsorbent particles not only have excellent adsorption capacity, but also have high thermal conductivity, high adsorption rate and desorption rate.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0029] (1) By adding a specific proportion of thermal conductivity additive in the granulation process, the present invention significantly enhances the thermal conductivity of the carrier particle. After amine impregnation, it shows a faster adsorption and desorption rate. When it comes to large-scale carbon capture, it can improve the overall efficiency of the system.

[0030] (2) By introducing amino materials into the porous carrier, the adsorbent mainly relies on chemical adsorption, and can not only capture under the flue gas CO2 concentration (15% CO2), but also be applicable to capture under low CO2 partial pressure conditions such as air.

[0031] (3) The production process of the adsorbent particles with high desorption rate prepared by the present invention is simple, low-cost, and has good adsorption performance.

[0032] (4) The present invention selects cheap silica gel as the main component of the carrier and clay as the binder, which reduces the cost of the material, and at the same time, the preparation of the present invention is simple and convenient. Description of the Drawings

[0033] Figure 1 is the SEM image of the carrier particles and adsorbent particles of the present invention;

[0034] Figure 2 is the schematic diagram of the saturated adsorption of the adsorbent of the present invention at room temperature;

[0035] Figure 3 is the thermal conductivity and thermal diffusivity diagram of the adsorbent particles of the present invention;

[0036] Figure 4 is the adsorption differential curve of the adsorbent particles of the present invention;

[0037] Figure 5 is the normalized desorption curve of the adsorbent particles of the present invention. Detailed Embodiments

[0038] The present invention will be further described below in conjunction with the embodiments and the drawings.

[0039] The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels without special instructions. The experimental methods without specific conditions in the embodiments usually follow conventional conditions or the conditions recommended by the manufacturer.

[0040] The raw materials and manufacturer's product numbers used in the present invention are shown in Table 1.

[0041] Table 1 Chemical reagents used and their detailed information

[0042]

[0043] Example 1

[0044] Preparation of carbon dioxide adsorbent particles

[0045] The adsorbent particles use silica gel as the main component of the carrier, adding attapulgite and methylcellulose to granulate by the extrusion-spheronization method, and finally obtaining solid amine adsorbent particles by impregnation with polyethyleneimine. In this example, boron nitride (BN) is not added. The specific operation steps are as follows:

[0046] (1) Calculate the masses of the main component of the carrier silica gel, the binder attapulgite, and methylcellulose. Weigh 10 g of silica gel, 2 g of attapulgite, and 1.5 g of methylcellulose. Add the powders together into a ball mill jar and use a ball mill to mix and grind at a speed of 600 rpm for 2 h to obtain a uniformly mixed powder;

[0047] (2) Mix 10 g of the milled powder with 10 ml of a 5% (by mass) aqueous solution of polyvinyl alcohol in deionized water to form a paste. Knead it until the dough does not break, put it into an extruder to extrude, producing rod-shaped samples with a diameter of 1 mm, and then put the rod-shaped samples into a spheronizer to spheronize to form particles with a diameter of 1 mm.

[0048] (3) Put the particles into a muffle furnace and heat them to 550 °C at a heating rate of 10 °C / min for calcination for 12 h to plasticize the particles, and then naturally cool them to room temperature to obtain carrier particles.

[0049] (4) Dissolve 3 g of polyethyleneimine (Mw 800) in 20 mL of ethanol and stir at room temperature for 1 h to fully dissolve the PEI. Transfer the solution into a flask of a rotary evaporator, add 7 g of carrier particles, rotate and evaporate at 50 °C for 2 h, and then put it into a vacuum drying oven and dry overnight at 70 °C to finally obtain carbon dioxide adsorbent particles BN0 / Type1-30.

[0050] Example 2

[0051] Preparation of carbon dioxide adsorbent particles

[0052] The adsorbent particles use silica gel as the main component of the carrier, adding attapulgite, methylcellulose, and BN to granulate by the extrusion-spheronization method, and finally obtaining solid amine adsorbent particles by impregnation with polyethyleneimine. The mass fraction of the corresponding BN is 5% (calculated based on 100% of the silica gel mass). The specific operation steps are as follows:

[0053] (1) Calculate the masses of the main component of the carrier silica gel, the binder attapulgite, methylcellulose, and the heat-conducting additive BN. Weigh 10 g of silica gel, 2 g of attapulgite, 1.5 g of methylcellulose, and 0.5 g of BN. Add the powders together into a ball mill jar and use a ball mill to mix and grind at a speed of 600 rpm for 2 h to obtain a uniformly mixed powder;

[0054] (2) Mix 10 g of the ball-milled powder with 10 ml of a 5% (by mass) aqueous solution of polyvinyl alcohol in deionized water to form a paste. Knead it until the dough does not break, put it into an extruder for extrusion to produce rod-shaped samples with a diameter of 1 mm, and then put the rod-shaped samples into a rounding machine to round them to form particles with a diameter of 1 mm.

[0055] (3) Put the particles into a muffle furnace, heat them to 550 °C at a heating rate of 10 °C / min and calcine for 12 h to plasticize the particles, and then cool them naturally to room temperature to obtain carrier particles.

[0056] (4) Dissolve 3 g of polyethyleneimine (Mw 800) in 20 mL of ethanol, stir at room temperature for 1 h to fully dissolve the PEI. Transfer the solution to a flask of a rotary evaporator, add 7 g of carrier particles, rotate and evaporate at 50 °C for 2 h, then put it into a vacuum drying oven and dry overnight at 70 °C to finally obtain carbon dioxide adsorbent particles BN5 / Type1-30.

[0057] Example 3

[0058] Preparation of Carbon Dioxide Adsorbent Particles

[0059] Silica gel is selected as the main component of the carrier for the adsorbent particles, and attapulgite, methyl cellulose, and BN are added. Granulation is carried out by the extrusion-rounding method, and solid amine adsorbent particles are finally prepared by impregnation with polyethyleneimine. The mass fraction of BN is 10% (calculated based on 100% of the mass of silica gel). The specific operation steps are as follows:

[0060] (1) Calculate the masses of the main component of the carrier, silica gel, the binder attapulgite, methyl cellulose, and the heat-conducting additive BN. Weigh 10 g of silica gel, 2 g of attapulgite, 1.5 g of methyl cellulose, and 1 g of BN. Add the powders together into a ball-milling tank and use a ball mill to mix and grind at a rotation speed of 600 rpm for 2 h to obtain a uniformly mixed powder;

[0061] (2) Mix 10 g of the ball-milled powder with 10 ml of a 5% (by mass) aqueous solution of polyvinyl alcohol in deionized water to form a paste. Knead it until the dough does not break, put it into an extruder for extrusion to produce rod-shaped samples with a diameter of 1 mm, and then put the rod-shaped samples into a rounding machine to round them to form particles with a diameter of 1 mm.

[0062] (3) Put the particles into a muffle furnace, heat them to 550 °C at a heating rate of 10 °C / min and calcine for 12 h to plasticize the particles, and then cool them naturally to room temperature to obtain carrier particles.

[0063] (4) Dissolve 3 g of polyethyleneimine (Mw 800) in 20 mL of ethanol, stir at room temperature for 1 h to fully dissolve the PEI. Transfer the solution to the flask of a rotary evaporator, add 7 g of carrier particles, perform rotary evaporation at 50 °C for 2 h, then place it in a vacuum drying oven and dry overnight at 70 °C to finally obtain carbon dioxide adsorbent particles BN10 / Type1-30.

[0064] Example 4

[0065] Preparation of carbon dioxide adsorbent particles

[0066] Silica gel is selected as the main component of the carrier for the adsorbent particles, attapulgite, methyl cellulose, and BN are added, and granulation is carried out by the extrusion and spheronization method. Finally, solid amine adsorbent particles are prepared by impregnation with polyethyleneimine. The mass fraction of BN is 15% (calculated based on 100% of the mass of silica gel). The specific operation steps are as follows:

[0067] (1) Calculate the masses of the main carrier component silica gel, the binder attapulgite, methyl cellulose, and the heat-conducting additive BN. Weigh 10 g of silica gel, 2 g of attapulgite, 1.5 g of methyl cellulose, and 1.5 g of BN. Add the powders together into a ball mill jar and use a ball mill to mix and grind at a rotation speed of 600 rpm for 2 h to obtain a uniformly mixed powder.

[0068] (2) Mix 10 g of the ball-milled powder with 10 ml of a 5% (mass fraction) aqueous solution of polyvinyl alcohol in deionized water to form a paste. Knead it until the dough does not break, then put it into an extruder to extrude, producing rod-shaped samples with a diameter of 1 mm. Put the rod-shaped samples into a spheronizer to spheronize to form particles with a diameter of 1 mm.

[0069] (3) Put the particles into a muffle furnace, heat it to 550 °C at a heating rate of 10 °C / min and calcine for 12 h to plasticize the particles, and then let it cool naturally to room temperature to obtain carrier particles.

[0070] (4) Dissolve 3 g of polyethyleneimine (Mw 800) in 20 mL of ethanol, stir at room temperature for 1 h to fully dissolve the PEI. Transfer the solution to the flask of a rotary evaporator, add 7 g of carrier particles, perform rotary evaporation at 50 °C for 2 h, then place it in a vacuum drying oven and dry overnight at 70 °C to finally obtain carbon dioxide adsorbent particles BN15 / Type1-30.

[0071] Example 5

[0072] Preparation of carbon dioxide adsorbent particles

[0073] The adsorbent particles use silica gel as the main component of the carrier, adding bentonite, methyl cellulose, and BN to granulate by the extrusion-spheronization method, and finally obtaining solid amine adsorbent particles by impregnation with polyethyleneimine. The mass fraction of BN is 5% (calculated based on 100% silica gel mass). The specific operation steps are as follows:

[0074] (1) Calculate the masses of the main component of the carrier, silica gel, the binder bentonite, methyl cellulose, and the heat-conducting additive BN. Weigh 10 g of silica gel, 2 g of bentonite, 1.5 g of methyl cellulose, and 0.5 g of BN. Add the powders together into a ball-milling jar and use a ball mill to mix and grind at a rotation speed of 600 rpm for 2 h to obtain a uniformly mixed powder;

[0075] (2) Mix 10 g of the ball-milled powder with 10 ml of a 5% (mass fraction) aqueous solution of polyvinyl alcohol in deionized water to form a paste. Knead it until the dough does not break, then put it into an extruder to extrude, producing rod-shaped samples with a diameter of 1 mm. Put the rod-shaped samples into a spheronizer to spheronize to form particles with a diameter of 1 mm.

[0076] (3) Put the particles into a muffle furnace and heat them to 550 °C at a heating rate of 10 °C / min for 12 h to plasticize the particles, and then let them cool naturally to room temperature to obtain carrier particles.

[0077] (4) Dissolve 3 g of polyethyleneimine (Mw 800) in 20 mL of ethanol and stir at room temperature for 1 h to fully dissolve the PEI. Transfer the solution into the flask of a rotary evaporator, add 7 g of carrier particles, rotate and evaporate at 50 °C for 2 h, and then put it into a vacuum drying oven and dry overnight at 70 °C to finally obtain carbon dioxide adsorbent particles BN5 / Type2-30.

[0078] Example 6

[0079] CO2 capture performance test. The adsorption capacity of the sample is measured using a synchronous thermal analyzer. The test process is divided into three stages:

[0080] (1) Pretreatment stage: Remove the skin of the crucible, weigh about 8 mg of the sample prepared in the above example and put it into the crucible. Pass N2 at a flow rate of 100 ml / min and heat it from room temperature to 100 °C at a heating rate of 10 °C / min, and keep it at 100 °C for 30 min to fully remove water, CO2, and other volatile gases in the adsorbent.

[0081] (2) Adsorption stage: Cool the furnace to the adsorption temperature of 35 °C, switch to 15% CO2 (the rest is nitrogen), and perform adsorption for 1 h to obtain an adsorption curve of the sample mass changing with time.

[0082] (3) Desorption stage: Switch the atmosphere back to pure N2, heat from the adsorption temperature to 100 °C at a heating rate of 10 °C / min, and hold at 100 °C for 30 min to complete the desorption process.

[0083] Example 7

[0084] The thermal conductivity was measured by a laser flash method thermal conductivity analyzer. Before testing, the samples prepared in the above examples were pressed into cylinders with a diameter of 12.7 mm and a height of about 2 mm. The laser of the thermal conductivity analyzer irradiates the lower surface of the sample from the bottom, and the detector detects the temperature change on the upper surface of the sample. After computer fitting, the thermal diffusivity α of the sample is obtained, and the thermal conductivity λ of the sample is calculated according to the following formula:

[0085] λ = C p ·α·ρ

[0086] where λ is the thermal conductivity W / (m·K), C p is the specific heat capacity of the sample J / (kg·K), α is the thermal diffusivity, m 2 / s, ρ is the sample density, kg / m 3 .

[0087] Test Example 1

[0088] The carbon dioxide adsorbent particles prepared in each example of the present invention were measured:

[0089] From Figure 1 in the SEM images, it can be seen that, as shown in Figure 1 (a), the silica gel surface has abundant nano-scale pores. After making the carrier particles of Example 1, as shown in Figure 1 (b), most of the nano-scale pores of the silica gel are retained.

[0090] The adsorption capacity of the sample was measured according to the method of Example 6. From Figure 2 in the thermogravimetric adsorption curve, it can be seen that compared with bentonite as a binder, the adsorbent with attapulgite added as a binder shows better adsorption capacity, and the adsorption capacity decreases with the gradual addition of BN.

[0091] The thermal conductivity of the sample was measured according to the method of Example 7. From Figure 3 it can be seen that after adding BN, the thermal conductivity and thermal diffusivity are significantly improved. Among them, the thermal conductivity of the particles with 5% BN added is increased by 29%, and the thermal diffusivity is increased by 11%.

[0092] Furthermore, obtained by differential fitting of the curve of Figure 2 , from Figure 4It can be seen that in terms of the adsorption rate, due to the appropriate addition of 5% BN, the prepared BN5 / Type1-30 adsorbent particles have the best adsorption rate. However, when 10% and 15% of BN are further added, due to excessive addition, the adsorption capacity decays severely, and the adsorption rate is significantly affected and decreased significantly. The desorption curve obtained by the method of Example 6 is processed to obtain a normalized desorption curve. From Figure 5 the normalized desorption curve, it can be seen that the prepared BN5 / Type1-30 adsorbent particles complete the desorption process first, taking 17.4 minutes. After calculation, it has the fastest average desorption rate of 0.054 mmol / (g·min), which is 42% higher than 0.038 mmol / (g·min) of the material without adding BN. The average desorption rates of Example 3 (10%) and Example 4 (15%) with excessive addition of BN are significantly lower than that of the material with 5% BN, and can only be increased by about 10-20% compared with the material without adding BN.

[0093] In summary, the present invention prepares carbon dioxide adsorbent particles with high desorption rate of specific BN content, which can not only ensure excellent adsorption capacity, but also significantly improve the thermal conductivity. More importantly, the average desorption rate of the material with 5% BN added is the most obvious, with the fastest desorption, and the adsorption rate is also improved. It has obvious advantages compared with the materials without adding BN or with BN content above 10%.

Claims

1. A method for preparing carbon dioxide adsorbent particles with a high desorption rate, characterized in that: The steps include: The silicon-based carrier, the binder and the thermal conductive additive are evenly mixed by ball milling; the evenly mixed powder is mixed with the polyvinyl alcohol solution, extruded into granules, and then calcined; the calcined particles are immersed in a modifier to obtain carbon dioxide adsorbent particles with a high desorption rate.

2. The method for preparing carbon dioxide adsorbent particles with a high desorption rate according to claim 1, characterized in that: The mass ratio of the silicon-based carrier, the binder and the thermal conductive additive is 100:30-40:1-10.

3. The method for preparing carbon dioxide adsorbent particles with a high desorption rate according to claim 1, characterized in that: The silicon-based carrier is preferably silica gel, and the thermal conductive additive is preferably boron nitride.

4. The method for preparing carbon dioxide adsorbent particles with a high desorption rate according to claim 1, characterized in that: The binder comprises an optional binder and a fixed binder, the optional binder is attapulgite or bentonite, and the fixed binder is methyl cellulose.

5. The method for preparing carbon dioxide adsorbent particles with a high desorption rate according to claim 4, characterized in that: The mass ratio of the optional binder to the fixing binder is 3-4:4-3.

6. The method for preparing carbon dioxide adsorbent particles with a high desorption rate according to claim 1, characterized in that: The mass ratio of the powder to polyvinyl alcohol is 1:1-2, the concentration of the polyvinyl alcohol solution is 2%-5%, the diameter of the extrudate after extrusion is 1-2 mm, and the diameter of the granulated particles is 1-2 mm.

7. The preparation method according to claim 1, characterized in that: The calcination temperature is 500-600° C. and the calcination time is 10-15 h.

8. The preparation method according to claim 1, characterized in that: The modifier containing an amine group is a polyethyleneimine solution, and the amount ratio of the calcined particles to the adsorbent is 500 mg: 10-20 ml. 9 . Carbon dioxide adsorbent particles with a high desorption rate prepared by the method for preparing carbon dioxide adsorbent particles with a high desorption rate according to claim 1 .

10. Use of the carbon dioxide adsorbent particles with a high desorption rate according to claim 9 in adsorbing carbon dioxide.

Images