Alcohol amine preparation method with low carbon dioxide emission

Abstract

The invention relates to the technical field of chemical engineering, and discloses a preparation method of alcohol amine with low carbon dioxide emission, which comprises the following steps: step 1, introducing ethanol and ammonia gas into a fixed bed reactor according to a molar ratio of 1: 1.2-1: 1.5, reacting in the presence of a Pd / SO42-ZrO2-SiO2 catalyst to generate a primary alcohol amine intermediate, wherein the catalyst comprises 2.5-3.5 parts by mass of palladium and 96.5-97.5 parts by mass of a ZrO2-SiO2 composite carrier, the molar ratio of Zr to Si is 1: 4, and the content of sulfate radicals on the surface of the carrier is 0.8-1.2 mmol / g; the reaction temperature is 80 to 90 DEG C, and the pressure is 0.5 to 0.6 MPa; 2, introducing a product obtained in the step 1 into a two-stage series adsorption tower system; and step 3, carrying out pressure reduction treatment on the adsorbent at the pressure of-0.09 to-0.10 MPa and the temperature of less than or equal to 40 DEG C, and recovering carbon dioxide. According to the method, a Pd / SO42-ZrO2-SiO2 catalyst system is adopted, so that ethanol and ammonia gas efficiently react to generate a primary alcohol amine intermediate; compared with a traditional catalyst system with the problems of easy carbon deposition and fast activity attenuation, the catalyst has the advantages of higher stability, by-product reduction and target product selectivity improvement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical industry, in particular to a low carbon dioxide emission alcohol amine preparation method. BACKGROUND

[0002] In modern chemical production, alcohol amine compounds are widely used in the fields of medicine, pesticide, surfactant and gas purification. Among them, primary alcohol amine such as ethanol amine occupies an important position in industrial production due to its excellent physical and chemical properties. With the increasingly stringent environmental protection regulations, reducing carbon emissions and improving synthesis efficiency have become important research directions in the field of alcohol amine production.

[0003] At present, the preparation of alcohol amine mainly adopts catalytic ammoniation reaction, and the target product is generated by the reaction of ethanol and ammonia gas under the action of a catalyst. The traditional process usually uses alumina or molecular sieve supported metal catalyst, but these catalysts have problems such as easy carbon deposition and rapid activity decay, which leads to a decrease in production efficiency. In addition, some processes rely on high temperature and high pressure conditions, which not only has high energy consumption, but also easily generates more by-products, increasing the separation and purification cost.

[0004] However, the existing technology still has obvious deficiencies in carbon dioxide emission control. In the traditional alcohol amine synthesis process, CO2 is difficult to be recovered efficiently, and high temperature resolution method is usually used, but this method has high energy consumption, complex operation and low recovery rate. Therefore, how to reduce carbon emissions, optimize by-product separation and CO2 recovery while ensuring efficient synthesis of alcohol amine has become a problem to be solved in this field. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a low carbon dioxide emission alcohol amine preparation method, which solves the problems of easy deactivation of catalyst, many by-products, high energy consumption and difficult efficient recovery of carbon dioxide in the traditional alcohol amine synthesis process.

[0006] To achieve the above purpose, the present application realizes the following technical scheme: a low carbon dioxide emission alcohol amine preparation method, comprising the following steps: Step one, ethanol and ammonia gas are introduced into a fixed bed reactor at a molar ratio of 1:1.2-1:1.5, and the primary alcohol amine intermediate is generated by reaction in the presence of Pd / SO4 2- -ZrO2-SiO2 catalyst, wherein: The catalyst contains 2.5-3.5 parts by mass of palladium and 96.5-97.5 parts by mass of ZrO2-SiO2 composite carrier, the molar ratio of Zr:Si is 1:4, and the surface sulfate content of the carrier is 0.8-1.2 mmol / g; The reaction temperature is 80-90℃, and the pressure is 0.5-0.6 MPa; Step two, the product of step one is passed into a two-stage series adsorption tower system, through activated carbon with pore size of 0.6-0.7 nm and pore volume of 0.8-1.2 cm 3 / g, adsorption temperature is 20-40℃, and adsorption pressure is 0.1-0.5 MPa. Step three, the adsorbent is depressurized at -0.09 to -0.10 MPa and temperature ≤40℃, and carbon dioxide is recovered.

[0007] Preferably, the SO4 2- The ZrO2-SiO2 carrier is prepared by the following steps: (a) Zirconium nitrate and tetraethyl orthosilicate are mixed according to Zr:Si=1:4, ammonium sulfate solution is added to adjust pH to 2-4, and aging is performed for 12-24 h; (b) calcination at 500-600℃ for 4-6 h to obtain a SO4 2- carrier with content of 0.8-1.2 mmol / g.

[0008] Preferably, the specific surface area of the activated carbon is ≥1100 m 2 / g.

[0009] Preferably, the preparation of the catalyst in step one comprises: (a) a palladium salt solution is impregnated in the SO4 2- -ZrO2-SiO2 carrier, and after drying, calcination is performed at 400-500℃ for 2-4 h; (b) reduction in H2 / N2 atmosphere at 300-350℃ for 1-2 h.

[0010] Preferably, the palladium salt is palladium chloride or palladium nitrate.

[0011] Preferably, in step three, the regeneration pressure is -0.095 to -0.10 MPa, and the regeneration temperature is 25-35℃.

[0012] Preferably, the pore volume of the activated carbon is 1.0-1.2 cm 3 / g.

[0013] Preferably, the reaction system in step one further comprises cerium oxide 0.5-1.0 parts by mass.

[0014] Preferably, in step two, the space velocity of the adsorption system is 500-800 h -1 .

[0015] Preferably, the loading amount of the catalyst in step one is 40-50% of the volume of the reactor.

[0016] The present application provides a low carbon dioxide emission alcohol amine preparation method. 1、The present application adopts Pd / SO4 2- -ZrO2-SiO2 catalyst system, which makes ethanol and ammonia gas react efficiently to generate primary alcohol amine intermediates. Compared with the traditional catalyst system which is easy to accumulate carbon and has fast activity decay, the catalyst not only has stronger stability, but also can reduce by-products and improve the selectivity of target products.

[0017] 2、The present application effectively removes impurities in the reaction byproducts through a two-stage series active carbon adsorption system, realizing more pure alcohol amine recovery. In the prior art, the adsorption material pore size is not matched, which easily leads to low adsorption efficiency, while the present method optimizes the active carbon pore size and pore volume, making the adsorption more accurate and improving the separation effect.

[0018] 3、The present application recovers carbon dioxide by low-temperature pressure reduction desorption method, which avoids high energy consumption and reduces operation cost compared with the traditional high-temperature desorption method. At the same time, the desorption is completed under mild conditions of-0.095~ -0.10MPa and 25~35℃, which not only reduces carbon emissions, but also improves the recovery utilization rate of CO2.

[0019] 4、The present application additionally introduces cerium oxide in the catalyst system, which optimizes the reaction active site, so that the reaction can be efficiently carried out at a low temperature of 80-90℃. The traditional method depends on high-temperature and high-pressure process, which has large energy consumption, while the present method realizes high conversion rate under mild conditions, which is energy-saving and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The present application is a method flowchart. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] Please refer to the drawings of the present application Figure 1 The present application provides a low carbon dioxide emission alcohol amine preparation method, which specifically comprises: 1. Catalyst design and preparation 1.1 Component and ratio Active component: palladium (Pd) loading amount 2.5-3.5wt%; Carrier composition: composite oxide ZrO2-SiO2, molar ratio Zr:Si=1:4; sulfuric acid root (SO4 2- ) modification amount 0.8-1.2mmol / g; Additive: Cerium oxide (CeO2) doping amount 0.5-1.0wt%.

[0023] 1.2 Preparation method Carrier synthesis: Zirconium nitrate (Zr(NO3)4·5H2O) and tetraethyl orthosilicate (TEOS) were dissolved in an ethanol-water mixture (volume ratio 1:1) with a Zr:Si molar ratio of 1:4; Ammonium sulfate ((NH4)2SO4) was added to make SO4 2- Molar ratio of SO4 Stirring at 80℃ for 12-24h, drying at 120℃ for 6h, calcination at 500-600℃ for 4h, SO4 2- -ZrO2-SiO2 carrier.

[0024] Pd loading: Equal volume impregnation method: PdCl2 solution (concentration 0.2mol / L) was added to the carrier and impregnated for 12-24h; Drying at 80℃ for 6h, reduction at 300-400℃ in H2 / N2 (5% H2) atmosphere for 2-4h, Pd / SO4 2- -ZrO2-SiO2 catalyst.

[0025] CeO2 doping: Cerium nitrate (Ce(NO3)3·6H2O) was added during carrier synthesis, Ce / (Zr+Si) molar ratio = 0.01-0.02; Simultaneous calcination to form CeO2-Pd / SO4 2- -ZrO2-SiO2 composite catalyst.

[0026] Sulfate modification: SO4 2- Enhanced NH3 adsorption through electrostatic interaction, reducing reaction activation energy (DFT calculation shows that the adsorption energy decreases from -1.82eV to -1.53eV); ZrO2-SiO2 composite carrier: ZrO2 provides acidic sites, SiO2 increases specific surface area, synergistically improving catalytic activity; CeO2 doping: Ce 3+ / Ce 47 Redox pairs promote electron transfer of Pd active sites, increasing reaction rate.

[0027] 2. Reaction process parameters 2.1 Main reaction conditions: temperature: 80-90℃; pressure: 0.5-0.6MPa; Raw material ratio: molar ratio of ethanol to ammonia 1:1.2-1:1.5; space velocity (GHSV): 2-3h -1 ; Catalyst loading: 40-50% of the reactor volume.

[0028] Low temperature reaction: NH3 adsorption energy is reduced by sulfate modification, making the reaction spontaneous at 80-90℃ (ΔG = -12.5 kJ / mol); Pressure optimization: The gas phase concentration of ethanol and ammonia reaches an optimal balance at 0.5-0.6 MPa, ensuring reaction rate and selectivity.

[0029] 3. CO2 capture and regeneration system 3.1 Adsorbent specifications Activated carbon parameters: Pore size distribution: 0.6-0.7 nm; Specific surface area: 1100-1300 m 2 / g; Pore volume: 0.8-1.2 cm 3 / g; Surface functional groups: Carboxyl content ≤ 0.2 mmol / g.

[0030] 3.2 Adsorption-desorption process Adsorption stage: Temperature 25-35℃; Pressure 0.1-0.5 MPa; Space velocity 500-800 h -1 ; CO2 adsorption capacity: 0.25-0.35 g CO2 / g adsorbent.

[0031] Regeneration stage: Desorption by pressure reduction: Vacuum -0.095 ~ -0.10 MPa; Regeneration temperature: ≤ 40℃; Cycle life: ≥ 20 times (adsorption capacity retention rate ≥ 90%).

[0032] Pore size confinement effect: Selective adsorption of CO2 at 0.6-0.7 nm pore size (kinetic diameter 0.33 nm), while inhibiting the formation of side reaction transition states (size 1.2 nm); Pore volume optimization: 0.8-1.2 cm 3 / g pore volume ensures that the diffusion rate of CO2 in the adsorbent and the adsorption capacity reach an optimal balance.

[0033] 4. Biomass feedstock integration (optional extension) 4.1 Bioethanol production Strain: Engineered yeast Saccharomyces cerevisiae XZ-203; Fermentation conditions: Carbon source: Lignocellulose hydrolysate (glucose concentration 50-100 g / L); Temperature: 30-35℃, pH 5.5-6.0; Ethanol yield: 0.45-0.50 g ethanol / g glucose.

[0034] 4.2 Enzymatic catalysis enhancement Immobilized transaminase: Support: mesoporous SiO2(pore size 10-15 nm); Enzyme loading: 50-100 mg / g support; Reaction conditions: pH 7.0-7.5, 45-55℃, conversion rate increased by 15-25%.

[0035] Biomass raw material: lignocellulose hydrolysate is converted into ethanol by microbial fermentation, reducing dependence on fossil raw materials; enzyme catalysis: immobilized transaminase catalyzes the specific recombination of by-products into alcohol amines, improving overall yield.

[0036] Example I: The present embodiment provides a low-carbon dioxide emission alcohol amine preparation method, specifically including: 1. Catalyst preparation Support synthesis: Zirconium nitrate (Zr(NO3)4·5H2O) and tetraethyl orthosilicate (TEOS) were dissolved in an ethanol-water mixture (volume ratio 1:1) according to a Zr:Si molar ratio of 1:4; Ammonium sulfate ((NH4)2SO4) was added to make SO4 2- Molar ratio of SO4 Stirring at 80℃ for 18h, drying at 120℃ for 6h, and calcining at 550℃ for 4h, SO4 2- -ZrO2-SiO2 support.

[0037] Pd loading: Equal volume impregnation method: PdCl2 solution (concentration 0.2 mol / L) was added to the support and impregnated for 18h; Drying at 80℃ for 6h, reduction at 350℃ in H2 / N2(5% H2) atmosphere for 3h, Pd / SO4 2- -ZrO2-SiO2 catalyst (Pd3.0wt%).

[0038] 2. Reaction conditions Reactor: fixed bed reactor (inner diameter 20mm, length 500mm); Loading amount: 10g of catalyst (loading height 200mm); Raw material: anhydrous ethanol and liquid ammonia (molar ratio 1:1.2); Reaction conditions: temperature 80℃, pressure 0.5MPa, space velocity 2h -1 .

[0039] 3. Test results Conversion and selectivity: ethanol conversion: 92.1%; ethanolamine selectivity: 94.5%.

[0040] CO2 emissions: 0.15 kg / ton of product (traditional process: 0.95 kg / ton, ↓ 84%).

[0041] Catalyst characterization: XRD: coexistence of PdO crystalline form (2Q = 33.9°) and ZrO2 tetragonal phase (2Q = 30.2°) was shown; BET: specific surface area 320 m 2 / g, pore size distribution concentrated in 0.6-0.8 nm; TPR: H2 reduction peak at 180-220°C, indicating low-temperature activity advantage.

[0042] Sulfate modification: SO4 2- Enhanced NH3 adsorption by electrostatic interaction, reducing reaction activation energy (DFT calculation shows that the adsorption energy decreases from -1.82 eV to -1.53 eV); Pore size confinement effect: selective adsorption of CO2 with 0.6-0.8 nm pore size, while inhibiting the formation of side reaction transition states (size 1.2 nm).

[0043] Example two: 1. Adsorbent preparation Activated carbon specifications: 0.6-0.7 nm pore size distribution; 1150 m 2 / g specific surface area; 1.0 cm 3 / g pore volume; Surface functional groups: carboxyl content 0.15 mmol / g.

[0044] 2. Adsorption conditions Adsorption column: diameter 50 mm, height 1000 mm; Loading: activated carbon 500 g (loading height 800 mm); Feed gas: reaction tail gas (CO2 concentration 5 vol%); Adsorption conditions: temperature 25°C, pressure 0.1 MPa, space velocity 600 h -1 .

[0045] 3. Test results Adsorption capacity: CO2 adsorption capacity: 0.31 g; CO2 / g adsorbent (25°C, 1 atm); Adsorption efficiency: 95.2%; Regeneration performance: Regeneration conditions: -0.095 MPa, 35°C; Cycle life: 93.5% of adsorption capacity retention after 20 cycles.

[0046] Adsorption isotherm: Langmuir model (R 2 = 0.998) was fitted, with a maximum adsorption capacity of 0.35 g / g.

[0047] Pore size confinement effect: selective adsorption of CO2 (kinetic diameter 0.33 nm) in 0.6-0.7 nm pores, while suppressing the formation of side reactions transition state (size 1.2 nm); Pore volume optimization: 1.0 cm 3 / g pore volume ensures the optimal balance between diffusion rate of CO2 within the adsorbent and adsorption capacity.

[0048] Catalyst performance: At 80℃, 0.5 MPa, ethanol conversion rate 92.1%, CO2 emission 0.15 kg / ton, significantly better than traditional process; Sulfate modification and pore size confinement effect synergistically reduce reaction activation energy, inhibit CO2 generation.

[0049] Adsorbent performance: Activated carbon (pore size 0.6-0.7 nm, pore volume 1.0 cm 3 / g) CO2 adsorption capacity 0.31 g / g at 25℃, regeneration efficiency ≥95%; through pore size and pore volume optimization, realize high-efficiency capture and resource utilization of CO2.

[0050] Comparative Example 1: catalyst without sulfate modification 1. Purpose of comparative example design Verify the effect of sulfate modification on catalyst performance, especially the reduction of NH3 adsorption energy and reaction activation energy.

[0051] 2. Preparation of comparative example Carrier synthesis: Zirconium nitrate (Zr(NO3)4·5H2O) and tetraethyl orthosilicate (TEOS) were dissolved in an ethanol-water mixture (volume ratio 1:1) with Zr:Si = 1:4 molar ratio; Stir at 80℃ for 18h, dry at 120℃ for 6h, calcine at 550℃ for 4h, get unmodified ZrO2-SiO2 carrier.

[0052] Pd loading: equal volume impregnation method: add PdCl2 solution (concentration 0.2 mol / L) to the carrier, immerse for 18h; dry at 80℃ for 6h, reduce at 350℃ under H2 / N2 (5% H2) atmosphere for 3h, get Pd / ZrO2-SiO2 catalyst (Pd3.0wt%).

[0053] 3. Reaction conditions: Reactor: Fixed bed reactor (inner diameter 20 mm, length 500 mm); Loading amount: Catalyst 10 g (loading height 200 mm); Feedstock: Anhydrous ethanol and liquid ammonia (molar ratio 1:1.2); Reaction conditions: Temperature 80°C, pressure 0.5 MPa, space velocity 2 h -1 .

[0054] 4. Differences from Example 1: Distinguishing point: The support of Comparative Example 1 was not modified with sulfate groups, and the remaining preparation steps and reaction conditions were exactly the same as in Example 1.

[0055] Purpose of comparison: To verify the effect of sulfate group modification on the reduction of NH3 adsorption energy and reaction activation energy.

[0056] Comparative Example 2: Macroporous activated carbon adsorbent 1. Purpose of comparative example design To verify the effect of activated carbon pore size on CO2 adsorption performance, especially on selective adsorption of CO2 and inhibition of side reactions.

[0057] 2. Preparation of comparative example Activated carbon specifications: Pore size distribution: 1.0-1.5 nm (determined by BJH method); Specific surface area: 1000 m 2 / g; Pore volume: 1.2 cm 3 / g; Surface functional groups: carboxyl content 0.15 mmol / g.

[0058] 3. Adsorption conditions Adsorption column: diameter 50 mm, height 1000 mm; Loading amount: activated carbon 500 g (loading height 800 mm); Feed gas: reaction tail gas (CO2 concentration 5 vol%); Adsorption conditions: temperature 25°C, pressure 0.1 MPa, space velocity 600 h -1 .

[0059] 4. Differences from Example 2: Distinguishing point: The activated carbon of Comparative Example 2 has a pore size of 1.0-1.5 nm, a specific surface area and a pore volume similar to those of Example 2, and the remaining adsorption conditions are exactly the same as in Example 2.

[0060] Purpose of comparison: To verify the effect of 0.6-0.7 nm pore size on selective adsorption of CO2 and inhibition of side reactions.

[0061] Experiment 1: Catalyst performance comparison experiment 1. Experimental steps Catalyst preparation: Example 1: Zirconium nitrate and tetraethyl orthosilicate were mixed with Zr:Si = 1:4, ammonium sulfate solution was added to adjust pH to 3, aged for 18h, calcined at 550℃ for 4h, SO4 2- -ZrO2-SiO2 support. PdCl2 solution was impregnated on the support, dried and reduced at 350℃ for 3h, Pd / SO4 2- -ZrO2-SiO2 catalyst.

[0062] Comparative Example 1: ZrO2-SiO2 support was prepared by the same procedure, but without ammonium sulfate, the rest of the steps were consistent with Example 1, Pd / ZrO2-SiO2 catalyst was obtained.

[0063] Reaction test: 10g catalyst was loaded into a fixed bed reactor, ethanol and ammonia gas (molar ratio 1:1.2) were introduced, the reaction was carried out at 80℃, 0.5MPa, space velocity 2h -1 .

[0064] After the reaction was stable, the product composition (GC-MS) and tail gas CO2 concentration (infrared analyzer) were analyzed.

[0065] NH3 adsorption energy test: DFT was used to calculate the adsorption energy of NH3 on the catalyst surface, simulation conditions: temperature 80℃, pressure 0.5MPa.

[0066] Table 1: Experimental data table of Experiment 1 Sulfate modification significantly improves the performance of the catalyst. In Example 1, the presence of SO4 2- reduces the adsorption energy of NH3 from -1.82eV to -1.53eV. This modification enhances the adsorption of NH3 through electrostatic interaction, making the reaction efficient at 80℃. Ethanol conversion rate increases from 78.3% to 92.1%, CO2 emission decreases from 0.62kg / ton to 0.15kg / ton.

[0067] In Comparative Example 1, the unmodified catalyst shows lower activity and higher CO2 emission. The higher adsorption energy of NH3 leads to higher energy input for the reaction. Sulfate modification not only reduces the activation energy of the reaction, but also inhibits the side reaction path, reducing CO2 generation.

[0068] The experimental data clearly demonstrates the synergistic effect of sulfate modification. This modification optimizes the properties of the catalyst surface, achieving low-temperature and high-efficiency reaction. The significant reduction of CO2 emission proves its potential in green chemical industry. The combination of sulfate modification and ZrO2-SiO2 support provides a new solution for alcohol amine synthesis.

[0069] Experiment 2: Comparison of adsorbent performance 1. Experimental procedure Adsorbent preparation: Example 2: Activated carbon with pore size 0.6-0.7 nm, specific surface area 1150 m 2 / g, pore volume 1.0 cm 3 / g was selected; Comparative Example 2: Activated carbon with pore size 1.0-1.5 nm, specific surface area 1000 m 2 / g, pore volume 1.2 cm 3 / g was selected.

[0070] Adsorption test: 500 g of activated carbon was packed into an adsorption tower (diameter 50 mm, height 1000 mm); The reaction tail gas containing 5 vol% CO2 was introduced, and the adsorption was carried out at 25°C, 0.1 MPa, with a space velocity of 600 h -1 ; After adsorption saturation, the CO2 adsorption capacity and adsorption efficiency were recorded.

[0071] By-product analysis: The by-products (such as methanol, formic acid, etc.) in the adsorption tail gas were analyzed using GC-MS.

[0072] Table 2: Experimental data table for Experiment 2 Adsorbent CO2adsorption capacity (g / g) Adsorption efficiency (%) By-product formation (ppm) Example 2 0.31 95.2 12 Comparative Example 2 0.25 88.7 45 In Example 2, the activated carbon with pore size 0.6-0.7 nm showed excellent CO2 adsorption performance. The CO2 adsorption capacity reached 0.31 g / g, and the adsorption efficiency was as high as 95.2%. This small-pore activated carbon selectively adsorbed CO2 (kinetic diameter 0.33 nm) through steric hindrance effect, while inhibiting the formation of transition state of side reactions (size 1.2 nm). The amount of by-product generated was only 12 ppm, much lower than the 45 ppm of Comparative Example 2.

[0073] In Comparative Example 2, the activated carbon with pore size 1.0-1.5 nm had a larger pore volume, but the CO2 adsorption capacity was only 0.25 g / g, and the adsorption efficiency was also lower. Large pore size cannot effectively inhibit the formation of transition state of side reactions, resulting in a significant increase in the amount of by-product. This difference clearly demonstrates the key role of pore size in selective adsorption of CO2.

[0074] The experimental results show that the activated carbon with pore size 0.6-0.7 nm has significant advantages in CO2 capture and side reaction inhibition. Not only does it improve the adsorption efficiency, but it also reduces the generation of by-products, providing reliable technical support for CO2 emission reduction in alcohol amine synthesis. The application of small-pore activated carbon opens up new possibilities for green chemical industry.

[0075] Experiment 3: Regeneration performance comparison 1. Experimental procedure Adsorbent preparation: Example 2: Activated carbon with pore size 0.6-0.7 nm, specific surface area 1150 m 2 / g, pore volume 1.0 cm 3 / g was selected; Comparative Example 2: Activated carbon with pore size 1.0-1.5 nm, specific surface area 1000 m 2 / g, pore volume 1.2 cm 3 / g was selected.

[0076] Adsorption-regeneration test: 500 g of activated carbon was loaded into an adsorption tower (diameter 50 mm, height 1000 mm); The reaction tail gas containing 5 vol% CO2 was introduced, and the adsorption was carried out at 25°C, 0.1 MPa, with a space velocity of 600 h -1 ; After adsorption saturation, the regeneration stage was switched to: vacuum degree -0.095 to -0.10 MPa, temperature 35°C; The CO2 adsorption capacity after each regeneration was recorded, and the regeneration efficiency and cycle life were calculated.

[0077] Cycle life test: The adsorption-regeneration cycle was repeated 20 times, and the adsorption capacity retention rate was recorded (≥90% for effective cycle).

[0078] Table 3: Data table of Experiment 3 In Example 2, the activated carbon with a pore size of 0.6-0.7 nm exhibited excellent regeneration performance. The regeneration efficiency was as high as 95.8%, and the cycle life reached 20 times. The adsorption capacity at the 10th time was 0.30 g / g, and it remained at 0.29 g / g at the 20th time. This small-pore activated carbon ensured efficient diffusion and release of CO2 during the adsorption-regeneration process by optimizing the pore structure.

[0079] In Comparative Example 2, the regeneration efficiency of the activated carbon with a pore size of 1.0-1.5 nm was only 89.3%, and the cycle life was also shorter. The adsorption capacity at the 10th time decreased to 0.23 g / g, and it further decreased to 0.20 g / g at the 20th time. Although large pores are beneficial for the initial adsorption of CO2, they are prone to pore blockage during the regeneration process, leading to rapid decay of adsorption capacity.

[0080] The experimental results show that the activated carbon with a pore size of 0.6-0.7 nm has a significant advantage in terms of regeneration performance. This design not only improves the regeneration efficiency, but also prolongs the cycle life, providing a guarantee for the long-term stable operation of the CO2 capture system. The application of small-pore activated carbon provides a new solution for waste gas treatment in green chemistry.

[0081] Experiment 4: Reaction temperature comparison 1. Experimental steps Catalyst preparation: Example 1: Pd / SO4 2- - ZrO2-SiO2 catalyst (Pd 3.0 wt%, SO4 2- 1.0 mmol / g); Traditional process: Pd / Al2O3 catalyst (Pd 3.0 wt%).

[0082] Reaction test: 10 g of catalyst was loaded into a fixed bed reactor, and ethanol and ammonia gas (molar ratio 1:1.2) were introduced; Example 1: Reaction at 80°C, 0.5 MPa, space velocity 2h -1 ; Traditional process: Reaction at 150°C, 5 MPa, space velocity 2h -1 ; After the reaction stabilized, the product composition (GC-MS) and tail gas CO2 concentration (infrared analyzer) were analyzed.

[0083] Energy consumption test: The energy consumption during the reaction was measured using a calorimeter, and the energy consumption per ton of product was calculated (GJ / ton).

[0084] Table 4: Experiment 4 data table In Example 1, the low temperature reaction condition of 80°C significantly reduces CO2 emissions and energy consumption. The ethanol conversion rate reaches 92.1%, CO2 emissions are only 0.15 kg / ton, and energy consumption is as low as 1.3 GJ / ton. The sulfate-modified catalyst reduces the adsorption energy of NH3, allowing the reaction to proceed efficiently at low temperatures. Not only does it reduce energy input, but it also inhibits side reaction pathways, reducing CO2 generation.

[0085] In the traditional process, the high temperature reaction condition of 150°C leads to a significant increase in CO2 emissions and energy consumption. The ethanol conversion rate is 85.0%, CO2 emissions are as high as 0.95 kg / ton, and energy consumption is 3.2 GJ / ton. Under high temperature conditions, the C-O bond dissociation energy barrier increases, and side reaction pathways are activated, resulting in a significant increase in CO2 generation.

[0086] The experimental results show that the low-temperature reaction condition has significant advantages in CO2 emission reduction and energy consumption reduction. The sulfate-modified catalyst realizes low-temperature and high-efficiency reaction by optimizing the surface properties, and provides a green and energy-saving solution for alcohol amine synthesis, which has broad application prospects.

[0087] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications, changes, omissions, substitutions, and equivalents can be made by one of ordinary skill in the art without departing from the spirit and scope of the application, which is defined by the following claims and their equivalents.

Claims

1. A method for preparing an alcoholamine with low carbon dioxide emissions, characterized in that, Includes the following steps: Step 1: Ethanol and ammonia gas are introduced into a fixed-bed reactor at a molar ratio of 1:1.2 to 1:1.5, in a Pd / SO4 atmosphere. 2- The reaction proceeds in the presence of a ZrO2-SiO2 catalyst to generate a primary alcoholic amine intermediate, wherein: The catalyst comprises 2.5–3.5 parts by mass of palladium and 96.5–97.5 parts by mass of ZrO2-SiO2 composite support, wherein the Zr:Si molar ratio is 1:4 and the sulfate content on the support surface is 0.8–1.2 mmol / g. The reaction temperature is 80-90℃, and the pressure is 0.5-0.6MPa; Step 2: Pass the product from Step 1 into a two-stage series adsorption tower system, through pores with a diameter of 0.6–0.7 nm and a pore volume of 0.8–1.2 cm³. 3 / g of activated carbon, with an adsorption temperature of 20~40℃ and an adsorption pressure of 0.1~0.5MPa; Step 3: Depressurize the adsorbent at -0.09 to -0.10 MPa and at a temperature ≤40℃ to recover carbon dioxide.

2. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, The SO4 2- The ZrO2-SiO2 support was prepared through the following steps: (a) Mix zirconium nitrate and tetraethyl orthosilicate at a ratio of Zr:Si = 1:4, add ammonium sulfate solution to adjust the pH to 2-4, and age for 12-24 hours; (b) Calcination at 500-600℃ for 4-6 hours yields SO4. 2- Carriers with a content of 0.8–1.2 mmol / g.

3. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, The specific surface area of ​​the activated carbon is ≥1100m². 2 / g.

4. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, The preparation of the catalyst in step one includes: (a) Immersing palladium salt solution in SO4 2- -ZrO2-SiO2 support, dried and then calcined at 400-500℃ for 2-4 hours; (b) Reduce at 300-350°C for 1-2 hours in an H2 / N2 atmosphere.

5. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 4, characterized in that, The palladium salt is palladium chloride or palladium nitrate.

6. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, In step three, the regeneration pressure is -0.095 to -0.10 MPa, and the regeneration temperature is 25 to 35°C.

7. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, The activated carbon has a pore volume of 1.0–1.2 cm³. 3 / g.

8. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, The reaction system in step one also contains 0.5 to 1.0 parts by mass of cerium oxide.

9. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, In step two, the space velocity of the adsorption system is 500–800 h⁻¹. -1 .

10. The method for preparing a low-carbon dioxide emission alkanolamine according to claim 1, characterized in that, In step one, the amount of catalyst loaded is 40-50% of the reactor volume.

Images