A low-temperature liquid-phase molecular sieve dechlorination agent and its preparation method

Abstract

A low-temperature liquid-phase molecular sieve dechlorinating agent and its preparation method belong to the technical field of dechlorination. The raw material composition of the low-temperature liquid-phase molecular sieve dechlorinating agent includes phosphorus-modified fine-crystallized molecular sieve, phytic acid-modified polyhydroxy polymer complexed metal ions, active silicon-coated nano-ceramic powder, oligoglycerol, pseudoboehmite, potassium silicate aqueous solution, and deionized water. For the low-temperature liquid-phase molecular sieve dechlorinating agent obtained in the present invention, in the reformate with a chlorine content of about 4 μg / L and a water content of about 25 μg / L, under the conditions of 70 °C, 1 MPa, and a liquid hourly space velocity of about 5 h⁻¹, the measured breakthrough chlorine capacity is 39.8 - 43.6%, the radial crushing strength is 134 - 148 N·cm⁻¹, and the attrition rate is 0.82 - 1.12%.

Description

Technical Field

[0001] The present invention relates to a low-temperature liquid-phase molecular sieve dechlorinating agent and a preparation method thereof, belonging to the technical field of dechlorination. Background Art

[0002] Catalytic reforming is one of the important production processes in petrochemical industry. In order to ensure the activity of the catalyst and achieve the best water-chlorine balance, water and organic chlorides need to be continuously injected. During this process, the lost water and HCl partially accumulate in the reformed product oil. The presence of a small amount of chlorine in the reformed product oil will seriously affect the quality of the top product and cause corrosion of the downstream stabilization system and extraction unit. Therefore, it is very necessary to carry out dechlorination treatment on the reformed product oil.

[0003] Using the solid adsorbent method to remove trace chlorides from reformed oil is the most economical solution. The principle of dechlorination is to fix HCl in the dechlorination agent through acid-base chemical reactions. When designing the dechlorination agent, the primary consideration is the selection of the active component. Alkali metals, alkaline earth metals, and transition metal oxides that can react with HCl have been studied extensively. For example, loading the oxides of Cu or Fe on activated carbon endows it with certain dechlorination performance. However, the activated carbon carrier itself has relatively low particle strength and high surface wear, and it is prone to particle pulverization during use, and the metal active components are likely to be lost. Especially under liquid-phase reaction conditions, the loss of active components is more serious. Currently, for industrial dechlorination agents, molecular sieves are mostly used as carriers, and the oxides of Cu, Mg, Fe, and Mn are often loaded onto porous carriers by the impregnation method. These oxide active components have a certain effect on removing HCl. For the molecular sieve-supported metal oxides prepared by the impregnation method, the state of these metal oxides in the molecular sieve is mostly surface adsorption. Since the diffusion resistance of HCl in the liquid phase is significantly higher than that in the gas phase, when removing HCl by liquid-phase adsorption, relatively high pressures are often used. In this case, the metal oxides adsorbed on the surface of the molecular sieve also tend to be lost, and it is difficult to maintain the non-decay of the adsorption performance over a long service time. Parameters such as the specific surface area, pore size, and pore size distribution of the molecular sieve carrier will also directly affect the dispersion of the active components in the dechlorination agent, thereby affecting the contact efficiency between the dechlorination active components and the inorganic chlorine in the reformed product oil and ultimately affecting the chlorine capacity of the dechlorination agent. In addition, after loading the metal oxides on the molecular sieve, it is necessary to mix and knead with binders and other additives and then cure and calcine to obtain finished dechlorination agents in the form of granules, strips, or other shapes. The binders and other additives added during the forming process and the related mixing, curing, and calcination processes are also crucial for the radial crushing strength and abrasion rate of the dechlorination agent. Too low radial crushing strength is likely to cause an increase in the pressure drop in the dechlorination device, posing a risk of damaging the device and seriously affecting the dechlorination effect. At the same time, the pulverization of the dechlorination agent is extremely likely to contaminate the materials in the device. The abrasion rate is mainly related to the attenuation of the dechlorination performance and the service life of the dechlorination agent. Too high an abrasion rate will lead to frequent replacement of the dechlorination agent, increasing the operating cost of the dechlorination device. Based on the related problems of the molecular sieve dechlorination agent described above, it can be seen that the molecular sieve dechlorination agent used for low-temperature liquid-phase dechlorination still needs to optimize the specific surface area, pore size, and pore size distribution of the molecular sieve to improve the chlorine capacity of the dechlorination agent. At the same time, it is also necessary to optimize the binders and other additives and the related mixing, curing, and calcination processes to obtain a low-temperature liquid-phase molecular sieve dechlorination agent with high crushing strength, low abrasion rate, and long-term durability.

[0004] CN117504807A discloses a macroporous liquid-phase dechlorination agent, which is composed of dechlorination active substance M-modified silica micropowder, inorganic macroporous material, and clay. Among them, the dechlorination active substance M is selected from one or more of Ca, Mg, and / or Zn, Fe, Cu elements; the breakthrough chlorine capacity of the liquid-phase dechlorination agent obtained in this patent is at most only 35.6%, which is not particularly ideal. In addition, using this kind of organic matter, silica micropowder, as the dechlorination active component, it is difficult to achieve good durability in terms of its radial crushing strength and attrition rate.

[0005] CN104437342A discloses a low-temperature liquid-phase molecular sieve dechlorination agent, which is suitable for removing hydrogen chloride in reformed product oil. The carrier of this dechlorination agent is carbon molecular sieve, the active components are oxides of alkali metals and alkaline earth metals, and the auxiliary components are copper oxide, iron oxide or zinc oxide. The highest value of the chlorine capacity of the molecular sieve dechlorination agent obtained in this patent is less than 33%. Moreover, the strength of carbon molecular sieve is generally relatively low, the service life is relatively short, and the replacement cycle will be relatively frequent, which will greatly increase the operation cost of the dechlorination device.

[0006] As can be seen above, there are still problems with low-temperature liquid-phase dechlorination agents such as low chlorine capacity, insufficient radial crushing strength, and high attrition rate. Therefore, developing a low-temperature liquid-phase molecular sieve dechlorination agent with high chlorine capacity, high crushing strength and low attrition rate is one of the effective means to reduce the operation cost of the catalytic reforming industry. Summary of the Invention

[0007] In view of the deficiencies of the above-mentioned existing technologies, the present invention provides a low-temperature liquid-phase molecular sieve dechlorination agent and its preparation method to achieve the following invention objectives: to prepare a low-temperature liquid-phase molecular sieve dechlorination agent with high breakthrough chlorine capacity, high radial crushing strength and low attrition rate.

[0008] To achieve the above invention objectives, the present invention adopts the following technical solutions:

[0009] A low-temperature liquid-phase molecular sieve dechlorination agent and its preparation method, the raw material composition of the low-temperature liquid-phase molecular sieve dechlorination agent includes phosphorus-modified fine-crystallized molecular sieve, phytic acid-modified polyhydroxy polymer complex metal ions, active silicon-coated nano-ceramic powder, oligoglycerol, pseudoboehmite, potassium silicate aqueous solution, deionized water;

[0010] The oligoglycerol is one of diglycerol, tetraglycerol, hexaglycerol, octaglycerol, decaglycerol, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio;

[0011] The following is a further improvement of the above technical solution:

[0012] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0013] Deionized water and phytate powder are added to a mixing kettle. After vigorously stirring and dispersing evenly, the stirring rate is reduced, and then a silicon source, an aluminum source, and hexamethylenediammonium hydroxide are added. After stirring into a gel, a peroxide is added, and stirring continues until the gel becomes milky white. Then, the milky white gel is quickly transferred to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene lining. The crystallization temperature is maintained, and crystallization is carried out at a constant temperature. After crystallization is completed, it is cooled and discharged, and separated by suction filtration. The separated solid is washed, dried, and then placed in a muffle furnace for roasting. After roasting is completed, it is cooled to room temperature to obtain a phosphorus-modified fine-crystallized molecular sieve;

[0014] The phytate is one of copper phytate, calcium phytate, magnesium phytate, zinc phytate, nickel phytate, cobalt phytate, iron phytate, vanadium phytate, titanium phytate, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio;

[0015] The silicon source is one of sodium silicate, potassium silicate, silica sol, tetraethyl orthosilicate, fumed silica, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio;

[0016] The aluminum source is one of aluminum isopropoxide, pseudo-boehmite, sodium metaaluminate, aluminum hydroxide, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio;

[0017] The peroxide is one of calcium peroxide, magnesium peroxide, zinc peroxide, lithium peroxide, sodium peroxide, potassium peroxide, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio;

[0018] The mass ratio of the deionized water, phytate powder, silicon source, aluminum source, hexamethylenediammonium hydroxide, and peroxide is 120 - 430:10 - 45:50 - 150:40 - 130:20 - 50:1 - 8;

[0019] For the vigorous stirring and dispersion, the stirring rate is 3000 - 4500 revolutions per minute;

[0020] For the reduction of the stirring rate, the stirring rate is reduced to 900 - 1600 revolutions per minute;

[0021] The crystallization temperature is 130 - 210 °C;

[0022] For the completion of crystallization, the crystallization time is 23 - 44 h;

[0023] For the washing, the operation is to wash with deionized water until the pH value of the washing liquid is 7 - 7.5;

[0024] For the drying, the drying temperature is 70 - 90 °C, and the drying time is 10 - 20 h;

[0025] For the roasting, the roasting temperature is 450 - 600 °C and the roasting time is 3 - 7 h.

[0026] Step 2: Prepare phytic acid - modified polyhydroxy polymer complexed metal ions

[0027] Add the polyhydroxy polymer, catalyst, and organic solvent into a reaction kettle. Under nitrogen protection, stir and heat to the reaction temperature. After the raw materials in the kettle are completely dissolved, maintain a constant - temperature condensation reflux state, add an aqueous phytic acid solution, and continue stirring and reacting at a constant temperature. After the reaction is completed, cool to room temperature and filter. Add anhydrous ethanol to the filtered liquid for recrystallization. The crystallized solid is washed with deionized water. Repeat the two - step operations of anhydrous ethanol recrystallization and deionized water washing until the pH value of the liquid obtained by dissolving the product in the deionized water washing operation is neutral. Then, add a water - soluble metal salt to the liquid with a neutral pH value, stand for complexation adsorption. After the complexation adsorption is saturated, recrystallize with anhydrous ethanol again. The solid obtained by recrystallization is freeze - dried to obtain phytic acid - modified polyhydroxy polymer complexed metal ions;

[0028] The polyhydroxy polymer is one of polyvinyl alcohol, starch, cellulose, cellulose derivatives, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio;

[0029] The catalyst is one of thiourea, sulfonamide, or a mixture composed of any two in any mass ratio;

[0030] The organic solvent is one of dimethyl sulfoxide, N,N - dimethylformamide, sulfolane, N - methylpyrrolidone;

[0031] The mass concentration of phytic acid in the aqueous phytic acid solution is 50 - 80 wt%;

[0032] In the water - soluble metal salt, the metal is one of copper, calcium, magnesium, zinc, nickel, cobalt, iron, vanadium, titanium, or a combination of any two or more;

[0033] The mass ratio of the polyhydroxy polymer, catalyst, organic solvent, and aqueous phytic acid solution is 20 - 130:5 - 13:200 - 600:10 - 40;

[0034] For the stirring and heating to the reaction temperature, the stirring rate is 600 - 1000 revolutions per minute and the reaction temperature is 100 - 140 °C;

[0035] For the continuous stirring and reacting at a constant temperature, the reaction time is 2 - 5 hours;

[0036] For the addition of anhydrous ethanol for recrystallization, the added mass of anhydrous ethanol is equal to the mass of the filtered liquid.

[0037] For the deionized water washing, the added mass of deionized water is equal to the mass of the filtered liquid.

[0038] For the addition of the water-soluble metal salt, the added mass of the water-soluble metal salt is equal to the mass of the solid obtained by recrystallization.

[0039] For the freeze-drying, the freezing temperature is -10~-5°C, and the drying time is 20~36 hours.

[0040] Step 3: Prepare the active silicon-coated nano-ceramic powder

[0041] Put the nano-ceramic powder, deionized water, and sodium hexametaphosphate into a dispersion kettle. After strongly dispersing them evenly at the first dispersion rate, raise the temperature and keep it constant at the reaction temperature, then reduce to the second dispersion rate and add the sodium metasilicate aqueous solution, and then dropwise add the sulfuric acid aqueous solution. Control the dropping rate to keep the pH value of the reaction system at 9~10.5. After the dropping is completed, stop the dispersion and heating, let it stand for aging. After the aging is completed, filter. The filtered solid is washed with water and dried to obtain the active silicon-coated nano-ceramic powder.

[0042] The nano-ceramic powder is one of nano-zirconia, nano-alumina, and nano-zirconium silicate.

[0043] The particle size of the nano-ceramic powder is 10~100 nm.

[0044] In the sodium metasilicate aqueous solution, the mass fraction of sodium metasilicate is 13~25 wt%.

[0045] In the sulfuric acid aqueous solution, the mass fraction of sulfuric acid is 8~11 wt%.

[0046] The mass ratio of the nano-ceramic powder, deionized water, sodium hexametaphosphate, sodium metasilicate aqueous solution, and sulfuric acid aqueous solution is 40~100:250~550:5~15:30~70:35~80.

[0047] The first dispersion rate is 8000~12000 revolutions per minute.

[0048] The second dispersion rate is 1500~3000 revolutions per minute.

[0049] The reaction temperature is 50~70°C.

[0050] For the standing and aging, the aging time is 5~10 hours.

[0051] For the water washing, the number of water washing times is until the pH of the washed liquid is neutral, and the mass of deionized water used for each washing is equal to the mass of the filtered solid.

[0052] For the drying process, the drying temperature is 60 - 80°C and the drying time is 16 - 30 hours.

[0053] Step 4: Prepare the slurry

[0054] Add the phosphorus-modified fine-crystallized molecular sieve, active-silica-coated nano-ceramic powder, and deionized water into a double planetary mixer. While controlling the stirring rate at 80 - 120 revolutions per minute and the dispersion rate at 7000 - 9500 revolutions per minute, stir and disperse for 5 - 7 hours. Then, add the phytic-acid-modified polyhydroxy polymer complex metal ions, oligoglycerol, pseudo-boehmite, and potassium silicate aqueous solution, and continue to stir and disperse for 6 - 10 hours to obtain a paste-like slurry.

[0055] In the potassium silicate aqueous solution, the mass fraction of potassium silicate is 10 - 20 wt%.

[0056] The feeding mass ratio of the phosphorus-modified fine-crystallized molecular sieve, phytic-acid-modified polyhydroxy polymer complex metal ions, active-silica-coated nano-ceramic powder, oligoglycerol, pseudo-boehmite, potassium silicate aqueous solution, and deionized water is 80 - 140:10 - 30:15 - 35:5 - 14:5 - 15:15 - 35:30 - 70.

[0057] Step 5: Extrusion molding

[0058] Inject the slurry into the extruder, adjust the screw speed and the diameter of the die orifice at the head to make the diameter of the extruded nearly circular particles 5 - 14 mm, and obtain the original particles of the dechlorination agent.

[0059] Step 6: Curing and calcination

[0060] Put the original particles of the dechlorination agent into a vacuum drying oven, dry at 45 - 70°C for 7 - 15 hours, then place them in a room-temperature environment with a relative air humidity of 45 - 60% and let them stand and age for 12 - 24 hours. Then transfer them to a muffle furnace, and with a heating rate of 0.5 - 3°C / min, heat from room temperature to 120 - 160°C, keep the temperature constant for curing for 6 - 10 hours. Then, with a heating rate of 2 - 4°C / min, raise the temperature to 450 - 580°C, keep the temperature constant for calcination for 12 - 20 hours, and then naturally cool to room temperature to obtain the low-temperature liquid-phase molecular sieve dechlorination agent after discharging.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] In the present invention, the silicoaluminophosphate molecular sieve is phosphorus-modified with phytate. Moreover, in the process of preparing the molecular sieve, in order to promote fine crystallization and thus obtain a molecular sieve with a larger specific surface area and richer micropores, peroxides are added in the present invention. The free radicals generated by the decomposition of peroxides promote the crystallization process of silicon and aluminum atoms in an alkaline environment, making the gelation network points of silicon and aluminum denser, thereby promoting the increase in the number of micropores and the refinement of pore diameters. In addition, the addition of phytate can not only introduce phosphorus elements with a relatively large atomic radius and a negative charge effect into the molecular sieve framework, but also bring metal ions into the molecular sieve framework at the same time. After sintering and oxidation, the metal oxides formed by the metal ions are not adsorbed on the surface of the internal micropores of the molecular sieve, but chemically bonded to the molecular sieve framework. In the actual use process of the dechlorination agent, this will greatly reduce the loss of metal oxides and significantly reduce the attenuation rate of the inorganic chlorine adsorption effect of the dechlorination agent. Moreover, the phosphorus element introduced into the molecular sieve framework forms a certain synergistic effect with the metal oxide during the adsorption process of inorganic chlorine, and finally the dechlorination agent obtained in the present invention has a very high breakthrough chlorine capacity;

[0063] In order to introduce a larger amount of metal oxides into the dechlorination agent and at the same time achieve the uniform dispersion of a large amount of metal oxides inside the dechlorination agent to ensure the maximum increase in the breakthrough chlorine capacity of the dechlorination agent, the present invention modifies the polyhydroxy polymer with phytate. The terminal hydroxyl groups of the polyhydroxy polymer and phytate are used to generate phytate ester bonds to increase the adsorption amount of metal ions by the polyhydroxy polymer. The terminal phosphoric carboxyl group and phytate ester bond of phytate can form relatively stable complexes with divalent and trivalent metal ions. This stable complex state can, firstly, increase the adsorption amount of metal ions, and secondly, ensure the uniform dispersion of metal ions inside the dechlorination agent. In addition, after the phytate-modified polyhydroxy polymer is completely ablated during the sintering process of the dechlorination agent, many fine micropores will be formed. The metal ions complexed on the phytate-modified polyhydroxy polymer, after sintering and oxidation, form oxides that are exactly located on the surface of the micropores. In this way, a huge specific surface area of metal oxides will be formed inside the dechlorination agent, which will also most efficiently improve the dechlorination performance of the dechlorination agent;

[0064] In order to improve the radial crushing strength and wear resistance of the dechlorination agent, nano-ceramic powder is added to the raw material composition of the dechlorination agent to improve the sintering density. During the preparation of the slurry, it is difficult to uniformly disperse the nano-ceramic powder. In order to promote the uniform dispersion degree of the nano-ceramic powder and the bonding tightness with other components during sintering, the present invention coats the nano-ceramic powder with active silicon. After being coated with active silicon, the active silicon can chemically react with potassium silicate in the slurry. After the reaction, a very strong chemical bond connection is formed between the nano-ceramic powder and the solidified system of the dechlorination agent. This will form a relatively dense network structure during the subsequent sintering process, and then the radial crushing strength and wear resistance of the dechlorination agent will be significantly improved;

[0065] In order to avoid the problem that during the calcination process of the dechlorination agent, excessive densification affects the adsorption process

[0066] and the penetration of inorganic chlorine into the interior of the dechlorination agent, resulting in the difficulty for the molecular sieve and metal oxide inside the dechlorination agent to contact the inorganic chlorine in the liquid phase, thereby affecting the effective adsorption of inorganic chlorine by the dechlorination agent, the present invention adds oligoglycerol as a pore-forming agent. During the calcination process, through the ablation of oligoglycerol, micropores are formed to construct micropore channels inside the dechlorination agent, so as to increase the contact area between inorganic chlorine and the molecular sieve and metal oxide inside the dechlorination agent. The main reasons for choosing oligoglycerol as the pore-forming agent are as follows: firstly, oligoglycerol has a low viscosity and good hydrophilicity, and is easily dissolved or evenly dispersed in the aqueous phase, which ensures the uniformity of the final micropore channels; secondly, the decomposition temperature range of oligoglycerol is relatively wide, which greatly avoids the possibility of forming macropores due to violent decomposition during the heating and constant-temperature processes of the solidification and calcination of the dechlorination agent, and will not have too much negative impact on the radial crushing strength and abrasion resistance of the dechlorination agent product;

[0067] 5. The low-temperature liquid-phase molecular sieve dechlorination agent obtained by the present invention, in the reforming product oil with a chlorine content of about 4 μg / L and a water content of about 25 μg / L, under the conditions of controlling 70 °C, 1 MPa, and a liquid hourly space velocity of about 5 h -1 the measured breakthrough chlorine capacity is 39.8 - 43.6%, and the radial crushing strength is 134 - 148 N·cm -1 , and the attrition rate is 0.82 - 1.12%. Description of the Drawings

[0068] Figure 1 is a scanning electron microscope photograph of the low-temperature liquid-phase molecular sieve dechlorination agent obtained in Example Ⅰ, with its cross-section magnified 10,000 times;

[0069] Figure 2 is a scanning electron microscope photograph of the low-temperature liquid-phase molecular sieve dechlorination agent obtained in Comparative Example 5, with its cross-section magnified 10,000 times. Detailed Embodiments

[0070] The following are descriptions of the preferred embodiments of the present invention. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0071] Example Ⅰ: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0072] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0073] Add deionized water and phytate powder into a mixing kettle. After vigorously stirring and dispersing evenly, reduce the stirring rate and then add a silicon source, an aluminum source, and hexamethylenediammonium hydroxide. After stirring into a gel-like substance, add a peroxide, and continue stirring until the gel-like substance turns milky white. Then quickly transfer the milky white gel-like substance to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene lining. Maintain the crystallization temperature and carry out isothermal crystallization. After the crystallization is completed, cool and discharge the material, and carry out suction filtration and separation. The separated solid is washed, dried, and then placed in a muffle furnace for roasting. After the roasting is completed, cool to room temperature to obtain a phosphorus-modified fine-crystallized molecular sieve;

[0074] The phytate is copper phytate;

[0075] The silicon source is sodium silicate;

[0076] The aluminum source is aluminum isopropoxide;

[0077] The peroxide is calcium peroxide;

[0078] The mass ratio of the deionized water, phytate powder, silicon source, aluminum source, hexamethylenediammonium hydroxide, and peroxide is 300:35:120:90:40:5;

[0079] For the vigorous stirring and dispersing, the stirring rate is 3500 revolutions per minute;

[0080] For the reduction of the stirring rate, the stirring rate is reduced to 1300 revolutions per minute;

[0081] The crystallization temperature is 150 °C;

[0082] For the completion of the crystallization, the crystallization time is 35 h;

[0083] For the washing, the operation is to wash with deionized water until the pH value of the washing liquid is 7.2;

[0084] For the drying, the drying temperature is 85 °C and the drying time is 17 h;

[0085] For the roasting, the roasting temperature is 550 °C and the roasting time is 6 h.

[0086] Step 2: Prepare a phytate-modified polyhydroxy polymer complex metal ion

[0087] Add polyhydroxy polymer, catalyst, and organic solvent into a reaction kettle. Under nitrogen protection, stir and heat to the reaction temperature. After the raw materials in the kettle are completely dissolved, maintain a constant temperature and condensation reflux state, add an aqueous solution of phytic acid, and continue stirring and reacting at a constant temperature. After the reaction is completed, cool to room temperature and filter to separate. Add anhydrous ethanol to the filtered liquid for recrystallization. Wash the crystallized solid with deionized water. Repeat the two-step operations of anhydrous ethanol recrystallization and deionized water washing until the pH value of the liquid obtained by dissolving the product in the deionized water washing operation is neutral. Then, add a water-soluble metal salt to the liquid with a neutral pH value, let it stand for complexation adsorption. After the complexation adsorption is saturated, recrystallize with anhydrous ethanol again. The solid obtained by recrystallization is freeze-dried to obtain a phytic acid-modified polyhydroxy polymer complexed with metal ions;

[0088] The polyhydroxy polymer is polyvinyl alcohol;

[0089] The catalyst is thiourea;

[0090] The organic solvent is dimethyl sulfoxide;

[0091] The mass concentration of phytic acid in the aqueous solution of phytic acid is 70 wt%;

[0092] In the water-soluble metal salt, the metal is copper;

[0093] The mass ratio of the polyhydroxy polymer, catalyst, organic solvent, and aqueous solution of phytic acid is 50:7:550:30;

[0094] When stirring and heating to the reaction temperature, the stirring rate is 900 revolutions per minute, and the reaction temperature is 130 °C;

[0095] When continuing to stir and react at a constant temperature, the reaction time is 4 hours;

[0096] When adding anhydrous ethanol for recrystallization, the added mass of anhydrous ethanol is equal to the mass of the filtered liquid;

[0097] When washing with deionized water, the added mass of deionized water is equal to the mass of the filtered liquid;

[0098] When adding the water-soluble metal salt, the added mass of the water-soluble metal salt is equal to the mass of the solid obtained by recrystallization;

[0099] For the freeze-drying, the freezing temperature is -6 °C, and the drying time is 32 hours.

[0100] Step 3: Prepare active silicon-coated nano-ceramic powder

[0101] Put nano-ceramic powder, deionized water, and sodium hexametaphosphate into a dispersion kettle. After strongly dispersing them evenly at the first dispersion rate, raise the temperature and keep it constant at the reaction temperature. Then, reduce the dispersion rate to the second rate and add an aqueous solution of sodium metasilicate. Next, dropwise add an aqueous solution of sulfuric acid, controlling the dropping rate to maintain the pH value of the reaction system at 10. After the dropping is complete, stop dispersion and heating, let it stand for aging. After the aging is completed, filter. The filtered solid is washed with water and dried to obtain nano-ceramic powder coated with active silicon;

[0102] The nano-ceramic powder is nano-zirconia;

[0103] The particle size of the nano-ceramic powder is 20 nm;

[0104] In the aqueous solution of sodium metasilicate, the mass fraction of sodium metasilicate is 20 wt%;

[0105] In the aqueous solution of sulfuric acid, the mass fraction of sulfuric acid is 9 wt%;

[0106] The mass ratio of the nano-ceramic powder, deionized water, sodium hexametaphosphate, aqueous solution of sodium metasilicate, and aqueous solution of sulfuric acid is 70:450:11:60:50;

[0107] The first dispersion rate is 10,000 revolutions per minute;

[0108] The second dispersion rate is 1,900 revolutions per minute;

[0109] The reaction temperature is 65 °C;

[0110] For the standing and aging, the aging time is 8 hours;

[0111] For the water washing, the number of water washing times is until the pH of the washing liquid is neutral, and the mass of deionized water used for each washing is equal to the mass of the filtered solid;

[0112] For the drying, the drying temperature is 75 °C and the drying time is 25 hours.

[0113] Step 4: Prepare the slurry

[0114] Put phosphorus-modified fine-crystallized molecular sieve, nano-ceramic powder coated with active silicon, and deionized water into a double planetary mixer. Control the stirring rate at 110 revolutions per minute and the dispersion rate at 8,500 revolutions per minute. After stirring and dispersing for 6 hours, add phytic acid-modified polyhydroxy polymer complex metal ions, diglycerol, pseudo-boehmite, and an aqueous solution of potassium silicate, and continue stirring and dispersing for 9 hours to obtain a paste-like slurry;

[0115] The diglycerol is diglycerol;

[0116] In the aqueous solution of potassium silicate, the mass fraction of potassium silicate is 16 wt%;

[0117] The feeding mass ratio of the phosphorus-modified fine-crystallized molecular sieve, phytic acid-modified polyhydroxy polymer complexed metal ions, active silicon-coated nano-ceramic powder, oligoglycerol, pseudo-boehmite, potassium silicate aqueous solution, and deionized water is 120:25:20:8:11:25:45.

[0118] Step 5: Extrusion molding

[0119] Inject the slurry into the extruder, adjust the screw speed and the diameter of the die orifice at the head to make the diameter of the extruded nearly circular particles 11 mm, and obtain the original particles of the dechlorination agent.

[0120] Step 6: Curing and calcination

[0121] Put the original particles of the dechlorination agent into a vacuum drying oven, dry at 65 °C for 11 hours, then place them in a room temperature environment with a relative air humidity of 55% and let them stand and age for 22 hours. Then transfer them to a muffle furnace, and increase the temperature from room temperature to 150 °C at a heating rate of 2 °C / min, keep the temperature constant for curing for 9 hours, then increase the temperature to 520 °C at a heating rate of 3 °C / min, keep the temperature constant for calcination for 17 hours, and then naturally cool to room temperature, and discharge to obtain the low-temperature liquid-phase molecular sieve dechlorination agent.

[0122] Example 2: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0123] Step 1: Prepare a phosphorus-modified fine-crystallized molecular sieve

[0124] Add deionized water and phytic acid salt powder to the mixing kettle, stir vigorously and disperse evenly, then reduce the stirring rate and add a silicon source, an aluminum source, and hexamethylenediammonium hydroxide. After stirring into a gel, add a peroxide, and continue stirring until the gel turns milky white. Then quickly transfer the milky white gel to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene inner lining, maintain the crystallization temperature, and carry out isothermal crystallization. After the crystallization is completed, cool and discharge, and carry out suction filtration and separation. The separated solid is washed, dried, and then placed in a muffle furnace for calcination. After the calcination is completed, cool to room temperature to obtain the phosphorus-modified fine-crystallized molecular sieve;

[0125] The phytic acid salt is calcium phytate;

[0126] The silicon source is potassium silicate;

[0127] The aluminum source is pseudo-boehmite;

[0128] The peroxide is magnesium peroxide;

[0129] The mass ratio of the deionized water, phytic acid salt powder, silicon source, aluminum source, hexamethylenediammonium hydroxide, and peroxide is 120:10:50:40:20:1;

[0130] The intense stirring and dispersion is carried out at a stirring rate of 3000 revolutions per minute;

[0131] The stirring rate is reduced, and the stirring rate is reduced to 900 revolutions per minute;

[0132] The crystallization temperature is 130 °C;

[0133] The crystallization is completed, and the crystallization time is 23 h;

[0134] For the washing, the operation is to wash with deionized water until the pH value of the washing liquid is 7;

[0135] For the drying, the drying temperature is 70 °C and the drying time is 10 h;

[0136] For the calcination, the calcination temperature is 450 °C and the calcination time is 3 h.

[0137] Step 2: Prepare phytic acid-modified polyhydroxy polymer complexed metal ions

[0138] Add the polyhydroxy polymer, catalyst, and organic solvent into the reaction kettle. Under nitrogen protection, stir and heat to the reaction temperature. After the raw materials in the kettle are completely dissolved, maintain a constant temperature and condensation reflux state, add the phytic acid aqueous solution, and continue to stir and react at a constant temperature. After the reaction is completed, cool to room temperature and filter and separate. Add anhydrous ethanol to the filtered liquid for recrystallization. The crystallized solid is washed with deionized water, and the two-step operations of anhydrous ethanol recrystallization and deionized water washing are repeatedly cycled until the pH value of the liquid obtained by dissolving the product in the deionized water washing operation is neutral. Then, add a water-soluble metal salt to the liquid with a neutral pH value, let it stand for complexation adsorption. After the complexation adsorption is saturated, recrystallize with anhydrous ethanol again. The solid obtained by recrystallization is freeze-dried to obtain phytic acid-modified polyhydroxy polymer complexed metal ions;

[0139] The polyhydroxy polymer is starch;

[0140] The catalyst is sulfonamide;

[0141] The organic solvent is N,N-dimethylformamide;

[0142] The mass concentration of phytic acid in the phytic acid aqueous solution is 50 wt%;

[0143] In the water-soluble metal salt, the metal is calcium;

[0144] The mass ratio of the polyhydroxy polymer, catalyst, organic solvent, and phytic acid aqueous solution is 20:5:200:10;

[0145] For the stirring and heating to the reaction temperature, the stirring rate is 600 revolutions per minute and the reaction temperature is 100 °C;

[0146] Perform the subsequent constant-temperature stirring reaction for 2 hours;

[0147] Add absolute ethanol for recrystallization, with the added mass of absolute ethanol being equal to the mass of the filtered liquid;

[0148] Wash with deionized water, with the added mass of deionized water being equal to the mass of the filtered liquid;

[0149] Add a water-soluble metal salt, with the added mass of the water-soluble metal salt being equal to the mass of the solid obtained from recrystallization;

[0150] Perform freeze-drying at a freezing temperature of -10°C and a drying time of 20 hours.

[0151] Step 3: Prepare the active silicon-coated nano-ceramic powder

[0152] Put the nano-ceramic powder, deionized water, and sodium hexametaphosphate into a dispersion kettle. After strongly dispersing them evenly at the first dispersion rate, raise the temperature and keep it constant at the reaction temperature, then reduce to the second dispersion rate and add the aqueous sodium metasilicate solution, and then dropwise add the aqueous sulfuric acid solution. Control the dropping rate to maintain the pH value of the reaction system at 9. After dropping, stop dispersion and heating, let it stand for aging. After aging is completed, filter. The filtered solid is washed with water and dried to obtain the active silicon-coated nano-ceramic powder;

[0153] The nano-ceramic powder is nano-aluminum oxide;

[0154] The particle size of the nano-ceramic powder is 10 nm;

[0155] In the aqueous sodium metasilicate solution, the mass fraction of sodium metasilicate is 13 wt%;

[0156] In the aqueous sulfuric acid solution, the mass fraction of sulfuric acid is 8 wt%;

[0157] The mass ratio of the nano-ceramic powder, deionized water, sodium hexametaphosphate, aqueous sodium metasilicate solution, and aqueous sulfuric acid solution is 40:250:5:30:35;

[0158] The first dispersion rate is 8000 revolutions per minute;

[0159] The second dispersion rate is 1500 revolutions per minute;

[0160] The reaction temperature is 50°C;

[0161] For the standing and aging, the aging time is 5 hours;

[0162] For the water washing, wash until the pH of the washing liquid is neutral. The mass of deionized water used for each washing is equal to the mass of the filtered solid;

[0163] For the drying, the drying temperature is 60 °C and the drying time is 16 hours.

[0164] Step 4: Prepare the slurry

[0165] Add the phosphorus-modified fine-crystallized molecular sieve, the active-silica-coated nano-ceramic powder, and deionized water into a double planetary mixer. Control the stirring rate at 80 revolutions per minute and the dispersion rate at 7000 revolutions per minute. After stirring and dispersing for 5 hours, then add the phytic-acid-modified polyhydroxy polymer complexed metal ions, the oligomeric glycerol, the pseudoboehmite, and the potassium silicate aqueous solution, and continue to stir and disperse for 6 hours to obtain a paste-like slurry;

[0166] The oligomeric glycerol is tetrameric glycerol;

[0167] In the potassium silicate aqueous solution, the mass fraction of potassium silicate is 10 wt%;

[0168] The feeding mass ratio of the phosphorus-modified fine-crystallized molecular sieve, the phytic-acid-modified polyhydroxy polymer complexed metal ions, the active-silica-coated nano-ceramic powder, the oligomeric glycerol, the pseudoboehmite, the potassium silicate aqueous solution, and deionized water is 80:10:15:5:5:15:30.

[0169] Step 5: Extrusion molding

[0170] Inject the slurry into the extruder, adjust the screw speed and the diameter of the die orifice at the head to make the diameter of the extruded near-circular particles 5 mm to obtain the original particles of the dechlorination agent.

[0171] Step 6: Curing and calcination

[0172] Put the original particles of the dechlorination agent into a vacuum drying oven, dry at 45 °C for 7 hours, then place them in a room-temperature environment with a relative air humidity of 45% and let them stand and age for 12 hours. Then transfer them to a muffle furnace, and at a heating rate of 0.5 °C / min, heat from room temperature to 120 °C, keep the temperature constant for curing for 6 hours, then at a heating rate of 2 °C / min, heat up to 450 °C, keep the temperature constant for calcination for 12 hours, and then naturally cool to room temperature, and discharge to obtain the low-temperature liquid-phase molecular sieve dechlorination agent.

[0173] Example 3: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0174] Step 1: Prepare the phosphorus-modified fine-crystallized molecular sieve

[0175] Deionized water and phytate powder are added to a mixing kettle. After being vigorously stirred and dispersed evenly, the stirring rate is reduced, and then a silicon source, an aluminum source, and hexamethylenediamine hydroxide are added. After stirring into a gel, a peroxide is added, and stirring continues until the gel turns milky white. Then, the milky white gel is quickly transferred to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene liner. The crystallization temperature is maintained, and crystallization is carried out at a constant temperature. After crystallization is completed, it is cooled and discharged, and separated by suction filtration. The separated solid is washed, dried, and then placed in a muffle furnace for roasting. After roasting is completed and cooled to room temperature, a phosphorus-modified fine-crystallized molecular sieve is obtained;

[0176] The phytate is magnesium phytate;

[0177] The silicon source is silica sol;

[0178] The aluminum source is sodium aluminate;

[0179] The peroxide is zinc peroxide;

[0180] The mass ratio of the deionized water, phytate powder, silicon source, aluminum source, hexamethylenediamine hydroxide, and peroxide is 430:45:150:130:50:8;

[0181] For the vigorous stirring and dispersion, the stirring rate is 4500 revolutions per minute;

[0182] For the reduction of the stirring rate, the stirring rate is reduced to 1600 revolutions per minute;

[0183] The crystallization temperature is 210 °C;

[0184] For the completion of crystallization, the crystallization time is 44 h;

[0185] For the washing, the operation is to wash with deionized water until the pH value of the wash liquor is 7.5;

[0186] For the drying, the drying temperature is 90 °C and the drying time is 20 h;

[0187] For the roasting, the roasting temperature is 600 °C and the roasting time is 7 h.

[0188] Step 2: Prepare a phytate-modified polyhydroxy polymer complex metal ion

[0189] Add a polyhydroxy polymer, a catalyst, and an organic solvent into a reaction kettle. Under nitrogen protection, stir and heat to the reaction temperature. After the raw materials in the kettle are completely dissolved, maintain a constant temperature and condensation reflux state, add an aqueous solution of phytic acid, and continue stirring and reacting at a constant temperature. After the reaction is completed, cool to room temperature and filter to separate. Add anhydrous ethanol to the filtered liquid for recrystallization. Wash the crystallized solid with deionized water. Repeat the two-step operations of anhydrous ethanol recrystallization and deionized water washing until the pH value of the liquid obtained by dissolving the product in the deionized water washing operation is neutral. Then, add a water-soluble metal salt to the liquid with a neutral pH value, let it stand for complexation adsorption. After the complexation adsorption is saturated, recrystallize with anhydrous ethanol again. The solid obtained by recrystallization is freeze-dried to obtain a phytic acid-modified polyhydroxy polymer complexed with metal ions;

[0190] The polyhydroxy polymer is cellulose;

[0191] The catalyst is thiourea;

[0192] The organic solvent is sulfolane;

[0193] The mass concentration of phytic acid in the aqueous solution of phytic acid is 80 wt%;

[0194] In the water-soluble metal salt, the metal is magnesium;

[0195] The mass ratio of the polyhydroxy polymer, the catalyst, the organic solvent, and the aqueous solution of phytic acid is 130:13:600:40;

[0196] For the stirring and heating to the reaction temperature, the stirring rate is 1000 revolutions per minute, and the reaction temperature is 140 °C;

[0197] For the continued stirring and reacting at a constant temperature, the reaction time is 5 hours;

[0198] For the addition of anhydrous ethanol for recrystallization, the added mass of anhydrous ethanol is equal to the mass of the filtered liquid;

[0199] For the deionized water washing, the added mass of deionized water is equal to the mass of the filtered liquid;

[0200] For the addition of the water-soluble metal salt, the added mass of the water-soluble metal salt is equal to the mass of the solid obtained by recrystallization;

[0201] For the freeze-drying, the freezing temperature is -5 °C, and the drying time is 36 hours.

[0202] Step 3: Prepare an active silicon-coated nano-ceramic powder

[0203] Put nano-ceramic powder, deionized water, and sodium hexametaphosphate into a dispersion kettle. After strongly dispersing them evenly at the first dispersion rate, raise the temperature and keep it constant at the reaction temperature. Then, reduce the rate to the second dispersion rate and add an aqueous solution of sodium metasilicate. Next, dropwise add an aqueous solution of sulfuric acid, controlling the dropping rate to maintain the pH value of the reaction system at 10.5. After the dropping is complete, stop dispersion and heating, let it stand for aging. After the aging is completed, filter. The solid filtered out is washed with water and dried to obtain nano-ceramic powder coated with active silicon;

[0204] The nano-ceramic powder is nano-zirconium silicate;

[0205] The particle size of the nano-ceramic powder is 100 nm;

[0206] In the aqueous solution of sodium metasilicate, the mass fraction of sodium metasilicate is 25 wt%;

[0207] In the aqueous solution of sulfuric acid, the mass fraction of sulfuric acid is 11 wt%;

[0208] The mass ratio of the nano-ceramic powder, deionized water, sodium hexametaphosphate, aqueous solution of sodium metasilicate, and aqueous solution of sulfuric acid is 100:550:15:70:80;

[0209] The first dispersion rate is 12,000 revolutions per minute;

[0210] The second dispersion rate is 3,000 revolutions per minute;

[0211] The reaction temperature is 70 °C;

[0212] For the standing and aging, the aging time is 10 hours;

[0213] For the water washing, the number of water washing times is until the pH of the washed-out liquid is neutral, and the mass of deionized water used for each washing is equal to the mass of the solid filtered out;

[0214] For the drying, the drying temperature is 80 °C and the drying time is 30 hours.

[0215] Step 4, Prepare the slurry

[0216] Put phosphorus-modified fine-crystallized molecular sieve, nano-ceramic powder coated with active silicon, and deionized water into a double planetary stirrer. Control the stirring rate at 120 revolutions per minute and the dispersion rate at 9,500 revolutions per minute. After stirring and dispersing for 7 hours, then add phytic acid-modified polyhydroxy polymer complex metal ions, hexaglycerol, pseudo-boehmite, and an aqueous solution of potassium silicate, and continue stirring and dispersing for 10 hours to obtain a paste-like slurry;

[0217] The hexaglycerol is hexaglycerol;

[0218] In the aqueous solution of potassium silicate, the mass fraction of potassium silicate is 20 wt%;

[0219] The feeding mass ratio of the phosphorus-modified fine-crystallized molecular sieve, phytic acid-modified polyhydroxy polymer complexed metal ions, active silicon-coated nano-ceramic powder, oligoglycerol, pseudoboehmite, potassium silicate aqueous solution, and deionized water is 140:30:35:14:15:35:70.

[0220] Step 5, extrusion molding

[0221] Inject the slurry into the extruder, adjust the screw speed and the diameter of the die orifice at the head to make the diameter of the extruded nearly circular particles 14 mm, and obtain the original particles of the dechlorination agent.

[0222] Step 6, curing and roasting

[0223] Put the original particles of the dechlorination agent into a vacuum drying oven, dry at 70 °C for 15 hours, then place them in a room temperature environment with a relative air humidity of 60% and let them stand and age for 24 hours. Then transfer them to a muffle furnace, and increase the temperature from room temperature to 160 °C at a heating rate of 3 °C / min, keep the temperature constant for curing for 10 hours, then increase the temperature to 580 °C at a heating rate of 4 °C / min, keep the temperature constant for roasting for 20 hours, and then naturally cool to room temperature, and discharge to obtain the low-temperature liquid-phase molecular sieve dechlorination agent.

[0224] Example 4: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0225] Step 1, preparation of phosphorus-modified fine-crystallized molecular sieve

[0226] The phytic acid salt is zinc phytic acid;

[0227] The silicon source is tetraethyl orthosilicate;

[0228] The aluminum source is aluminum hydroxide;

[0229] The peroxide is lithium peroxide;

[0230] Other operations are the same as in Example 1;

[0231] Step 2, preparation of phytic acid-modified polyhydroxy polymer complexed metal ions

[0232] The polyhydroxy polymer is a cellulose derivative;

[0233] The catalyst is a mixture composed of one or both of thiourea and sulfonamide in any mass ratio;

[0234] The organic solvent is N-methylpyrrolidone;

[0235] The mass concentration of phytic acid in the phytic acid aqueous solution is 50-80 wt%;

[0236] In the water-soluble metal salt, the metal is zinc;

[0237] Other operations are the same as those in Example 1.

[0238] Step 3: The operation is the same as that in Example 1;

[0239] Step 4: Prepare the slurry

[0240] The oligoglycerol is octaglycerol;

[0241] Other operations are the same as those in Example 1.

[0242] Steps 5 and 6: The operations are the same as those in Example 1.

[0243] Example 5: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0244] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0245] The phytate is nickel phytate;

[0246] The silicon source is fumed silica;

[0247] The peroxide is sodium peroxide;

[0248] Other operations are the same as those in Example 1.

[0249] Step 2: Prepare phytate-modified polyhydroxy polymer complex metal ions

[0250] In the water-soluble metal salt, the metal is nickel;

[0251] Other operations are the same as those in Example 1.

[0252] Step 3: The operation is the same as that in Example 1;

[0253] Step 4: Prepare the slurry

[0254] The oligoglycerol is decaglycerol;

[0255] Other operations are the same as those in Example 1.

[0256] Steps 5 and 6: The operations are the same as those in Example 1.

[0257] Example 6: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0258] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0259] The phytate is cobalt phytate;

[0260] The peroxide is potassium peroxide;

[0261] Other operations are the same as those in Example 1.

[0262] Step 2: Prepare phytic acid-modified polyhydroxy polymer complexed with metal ions

[0263] In the water-soluble metal salt, the metal is cobalt;

[0264] Other operations are the same as those in Example 1.

[0265] The operations in Steps 3, 4, 5, and 6 are the same as those in Example 1.

[0266] Example 7: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0267] The phytic acid salt is ferric phytate;

[0268] Other operations are the same as those in Example 1.

[0269] Step 2: Prepare phytic acid-modified polyhydroxy polymer complexed with metal ions

[0270] In the water-soluble metal salt, the metal is iron;

[0271] Other operations are the same as those in Example 1;

[0272] The operations in Steps 3, 4, 5, and 6 are the same as those in Example 1.

[0273] Example 8: A preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0274] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0275] Add deionized water and phytic acid salt powder into a mixing kettle. After vigorously stirring and dispersing evenly, reduce the stirring rate and then add a silicon source, an aluminum source, and hexamethylenediammonium hydroxide. After stirring into a gel-like substance, add a peroxide, and continue stirring until the gel-like substance turns milky white. Then quickly transfer the milky white gel-like substance to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene lining. Maintain the crystallization temperature and carry out isothermal crystallization. After crystallization is completed, cool and discharge the material, and carry out suction filtration separation. The separated solid is washed, dried, and then placed in a muffle furnace for roasting. After roasting is completed, cool to room temperature to obtain the phosphorus-modified fine-crystallized molecular sieve;

[0276] The phytic acid salt is vanadyl phytate;

[0277] Other operations are the same as those in Example 1.

[0278] Step 2: Prepare phytic acid-modified polyhydroxy polymer complexed with metal ions

[0279] In the water-soluble metal salt, the metal is vanadium;

[0280] Other operations are the same as those in Example 1;

[0281] The operations in Steps 3, 4, 5, and 6 are the same as those in Example 1.

[0282] Example 9: Preparation method of a low-temperature liquid-phase molecular sieve dechlorination agent

[0283] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0284] The phytate is titanium phytate;

[0285] Other operations are the same as those in Example 1.

[0286] Step 2: Prepare phytate-modified polyhydroxy polymer complex metal ions

[0287] In the water-soluble metal salt, the metal is titanium;

[0288] Other operations are the same as those in Example 1;

[0289] Steps 3, 4, 5, and 6 are the same as those in Example 1.

[0290] Comparative Example 1: On the basis of Example 1, in Step 1 of preparing the phosphorus-modified fine-crystallized molecular sieve, no peroxide is added, and 5 parts of peroxide are replaced with 5 parts of deionized water equally. The specific operation is as follows:

[0291] Step 1: Prepare phosphorus-modified fine-crystallized molecular sieve

[0292] Add deionized water and phytate powder into a mixing kettle. After stirring vigorously and dispersing evenly, reduce the stirring rate and then add the silicon source, aluminum source, and hexamethylenediammonium hydroxide. After stirring into a gel, quickly transfer the gel to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene lining. Maintain the crystallization temperature and carry out isothermal crystallization. After crystallization is completed, cool and discharge the material, carry out suction filtration separation. The separated solid is washed, dried, and then put into a muffle furnace for roasting. After roasting is completed, cool to room temperature to obtain the phosphorus-modified fine-crystallized molecular sieve;

[0293] The mass ratio of the deionized water, phytate powder, silicon source, aluminum source, and hexamethylenediammonium hydroxide is 305:35:120:90:40;

[0294] Other operations are the same as those in Example 1;

[0295] Steps 2, 3, 4, and 5 are the same as those in Example 1.

[0296] Comparative Example 2: On the basis of Example 1, Step 2 of preparing the phytate-modified polyhydroxy polymer complex metal ions is not carried out. In Step 2, only the phytate-modified polyhydroxy polymer is prepared. In Step 4 of preparing the slurry, 25 parts of the phytate-modified polyhydroxy polymer complex metal ions are replaced with 25 parts of the phytate-modified polyhydroxy polymer equally. The specific operation is as follows:

[0297] Step 1: The operation is the same as that in Example 1;

[0298] Step 2: Preparation of phytic acid-modified polyhydroxy polymer

[0299] Add the polyhydroxy polymer, catalyst, and organic solvent into a reaction kettle. Under nitrogen protection, stir and heat to the reaction temperature. After the raw materials in the kettle are completely dissolved, maintain a constant temperature and condensing reflux state, add the phytic acid aqueous solution, and continue to stir and react at a constant temperature. After the reaction is completed, cool to room temperature and filter. Add anhydrous ethanol to the filtered liquid for recrystallization. The crystallized solid is washed with deionized water. Repeat the two-step operations of anhydrous ethanol recrystallization and deionized water washing until the pH value of the liquid obtained by dissolving the product in the deionized water washing operation is neutral. Then, perform anhydrous ethanol recrystallization again. The solid obtained by recrystallization is freeze-dried to obtain the phytic acid-modified polyhydroxy polymer;

[0300] The polyhydroxy polymer is polyvinyl alcohol;

[0301] The catalyst is thiourea;

[0302] The organic solvent is dimethyl sulfoxide;

[0303] The mass concentration of phytic acid in the phytic acid aqueous solution is 70 wt%;

[0304] The mass ratio of the polyhydroxy polymer, catalyst, organic solvent, and phytic acid aqueous solution is 50:7:550:30;

[0305] When stirring and heating to the reaction temperature, the stirring rate is 900 revolutions per minute, and the reaction temperature is 130 °C;

[0306] When continuing to stir and react at a constant temperature, the reaction time is 4 hours;

[0307] When adding anhydrous ethanol for recrystallization, the added mass of anhydrous ethanol is equal to the mass of the filtered liquid;

[0308] When washing with deionized water, the added mass of deionized water is equal to the mass of the filtered liquid;

[0309] When freeze-drying, the freezing temperature is -6 °C, and the drying time is 32 hours.

[0310] The operation of Step 3 is the same as that of Example 1;

[0311] Step 4: Preparation of slurry

[0312] Replace 25 parts of the phytic acid-modified polyhydroxy polymer complexed with metal ions with 25 parts of the phytic acid-modified polyhydroxy polymer, and the other operations are the same as those in Example 1;

[0313] The operations of Steps 5 and 6 are the same as those in Example 1.

[0314] Comparative Example 3: On the basis of Example 1, step 2, the preparation of phytic acid-modified polyhydroxy polymer complexed metal ions is not carried out. In step 2, only polyhydroxy polymer complexed metal ions are prepared. In step 4, the preparation of the slurry, 25 parts of phytic acid-modified polyhydroxy polymer complexed metal ions are replaced with 25 parts of polyhydroxy polymer complexed metal ions in equal amounts. The specific operation is as follows:

[0315] The operation of step 1 is the same as that of Example 1;

[0316] Step 2, preparation of polyhydroxy polymer complexed metal ions

[0317] Dissolve the polyhydroxy polymer in deionized water. After complete dissolution, then add a water-soluble metal salt thereto, and let it stand for complexation adsorption. After the complexation adsorption is saturated, recrystallize with absolute ethanol. The solid obtained by recrystallization is freeze-dried to obtain polyhydroxy polymer complexed metal ions;

[0318] The polyhydroxy polymer is polyvinyl alcohol;

[0319] In the water-soluble metal salt, the metal is copper;

[0320] The mass ratio of the polyhydroxy polymer to deionized water is 50:580;

[0321] When adding absolute ethanol for recrystallization, the added mass of absolute ethanol is equal to the total mass of the polyhydroxy polymer and deionized water;

[0322] When adding the water-soluble metal salt, the added mass of the water-soluble metal salt is equal to the mass of the solid obtained by recrystallization;

[0323] For the freeze-drying, the freezing temperature is -6°C and the drying time is 32 hours.

[0324] The operation of step 3 is the same as that of Example 1;

[0325] Step 4, preparation of the slurry

[0326] Replace 25 parts of phytic acid-modified polyhydroxy polymer complexed metal ions with 25 parts of polyhydroxy polymer complexed metal ions in equal amounts, and other operations are the same as those in Example 1;

[0327] The operations of steps 5 and 6 are the same as those in Example 1.

[0328] Comparative Example 4: On the basis of Example 1, step 3, the preparation of active silicon-coated nano-ceramic powder is not carried out. In step 4, the preparation of the slurry, 20 parts of active silicon-coated nano-ceramic powder are replaced with 20 parts of nano-ceramic powder in equal amounts. The specific operation is as follows:

[0329] The operations of steps 1 and 2 are the same as those in Example 1;

[0330] Do not perform Step 3, preparing the active silicon-coated nano-ceramic powder;

[0331] Step 4, preparing the slurry

[0332] Replace 20 parts of the active silicon-coated nano-ceramic powder with 20 parts of nano-ceramic powder in equal amount, and other operations are the same as those in Example 1;

[0333] The operations of Steps 5 and 6 are the same as those in Example 1.

[0334] Comparative Example 5: On the basis of Example 1, in Step 4, preparing the slurry, do not add oligoglycerol, and replace 11 parts of oligoglycerol with 11 parts of deionized water in equal amount. The specific operations are as follows:

[0335] The operations of Steps 1, 2, and 3 are the same as those in Example 1;

[0336] Step 4, preparing the slurry

[0337] Replace 11 parts of oligoglycerol with 11 parts of deionized water in equal amount, and other operations are the same as those in Example 1;

[0338] The operations of Steps 5 and 6 are the same as those in Example 1.

[0339] Performance test:

[0340] Test the breakthrough chlorine capacity of the low-temperature liquid-phase molecular sieve dechlorinating agent obtained in Examples 1, 2, 3, 4, 5, 6, 7, 8, 9 and Comparative Examples 1, 2, 3, 4, 5. The test method is as follows: Feed the reformate with a chlorine content of about 4 μg / L and a water content of about 25 μg / L into the dechlorinating agent for a liquid-phase dynamic dechlorination experiment under the conditions of 70 °C, 1 MPa, and a liquid hourly space velocity of 5 h -1 to measure the chlorine content in the reformate flowing out of the dechlorination tank. When the chlorine content in the effluent is greater than 0.5 μg / L, it can be regarded as breakthrough. According to the formula: breakthrough chlorine capacity = (mass content of chlorine in the dechlorinating agent after breakthrough) / (total mass of the dechlorinating agent after breakthrough) × 100%, the breakthrough chlorine capacity of the dechlorinating agent is obtained;

[0341] Refer to "HG / T 2782-2024 Determination of the Crushing Strength of Chemical Catalyst Particles" to test the radial crushing strength;

[0342] Refer to "HG / T 2976-2011 Determination of the Abrasion Rate of Chemical Fertilizer Catalysts" to test the abrasion rate;

[0343] The specific test results are shown in Table 1:

[0344] Table 1

[0345] As can be seen from the data in Table 1, the breakthrough chlorine capacity of Examples 1-9 is all above 39%, the radial crushing strength is greater than 130 N•cm -1 , and the attrition rate is all below 1.2%. This shows that the low-temperature liquid-phase molecular sieve dechlorination agent obtained by the present invention has the performance characteristics of high breakthrough chlorine capacity, high radial crushing strength and low attrition rate; in Comparative Example 1, during the step of preparing the phosphorus-modified fine-crystallized molecular sieve, no peroxide is added, and the breakthrough chlorine capacity of Comparative Example 1 drops sharply to 28.3 N•cm -1 , and the radial crushing strength and attrition rate hardly change. This shows that peroxide has a very significant impact on the inorganic chlorine adsorption performance of the molecular sieve dechlorination agent. The reason may be that peroxide can promote the fine crystallization of the molecular sieve, thereby reducing the micropore aperture of the molecular sieve, increasing the specific surface area of the molecular sieve, and ultimately greatly improving the adsorption capacity of the molecular sieve for inorganic chlorine; in Comparative Example 2, no metal ions are complexed on the phytic acid-modified polyhydroxy polymer. The radial crushing strength and attrition rate of Comparative Example 2 do not change, but the breakthrough chlorine capacity of Comparative Example 2 drops significantly to 27.5 N•cm -1 . This shows that after the phytic acid-modified polyhydroxy polymer complexes metal ions, the metal ions can form metal oxides in the final dechlorination agent product, and these metal oxides can effectively contact inorganic chlorine and play a very effective adsorption role for inorganic chlorine; in Comparative Example 3, the phytic acid-modified polyhydroxy polymer complexing metal ions is replaced with an equal amount of polyhydroxy polymer complexing metal ions, that is, the polyhydroxy polymer is directly complexed with metal ions without phytic acid modification. The breakthrough chlorine capacity of Comparative Example 3 drops to 29.1 N•cm -1 , and the radial crushing strength and attrition rate of Comparative Example 3 decrease slightly. This shows that if the polyhydroxy polymer is not phytic acid-modified, it is difficult to effectively adsorb metal ions, so it will cause a significant drop in the breakthrough chlorine capacity, and the metal ions also have a certain impact on the radial crushing strength and attrition rate of the dechlorination agent during the sintering process to form oxides; in Comparative Example 4, the nano-ceramic powder is not coated with active silicon, and the breakthrough chlorine capacity of Comparative Example 4 drops significantly to 32.4 N•cm -1 , the radial crushing strength drops significantly, and the attrition rate increases sharply. This shows that the nano-ceramic powder coated with active silicon can be very evenly dispersed during the preparation of the slurry step, thereby playing a positive role in increasing the micropores inside the dechlorination agent, and can also maximize the radial crushing strength and attrition rate of the dechlorination agent; in Comparative Example 5, no oligoglycerol is added during the preparation of the slurry step, and the breakthrough chlorine capacity of Comparative Example 5 drops to 28.3 N•cm -1, the radial crushing strength increases significantly and the wear rate decreases significantly. This indicates that oligoglycerol mainly acts as a pore-forming agent, which can form micropores during the curing and sintering process of the dechlorination agent, enabling inorganic chlorine to penetrate smoothly into the interior of the dechlorination agent, promoting the effective contact between inorganic chlorine and the molecular sieve and metal oxide inside the dechlorination agent, and thus ensuring the high breakthrough chlorine capacity of the dechlorination agent. However, the addition of the pore-forming agent oligoglycerol has a certain negative effect on the radial crushing strength of the dechlorination agent, and the numerous micropores formed by the addition of oligoglycerol also have a relatively obvious impact on the wear resistance of the dechlorination agent.

[0346] Appendix Figure 1 and Appendix Figure 2 are respectively the scanning electron microscope photos of the low-temperature liquid-phase molecular sieve dechlorination agents obtained in Example 1 and Comparative Example 5, with each cross-section magnified 10,000 times. It can be clearly seen that the density of Appendix Figure 2 is significantly greater than that of Appendix Figure 1 , that is, Appendix Figure 1 has more micropores, while Appendix Figure 2 has very few micropores. This shows that for the dechlorination agent obtained in Comparative Example 5 without adding oligoglycerol, it is difficult to construct more micropore channels or micropore gaps inside, which leads to too large a penetration resistance of inorganic chlorine in the liquid phase into the interior of the dechlorination agent, affecting the adsorption of inorganic chlorine, and ultimately resulting in a significant reduction in the breakthrough chlorine capacity of Comparative Example 5.

[0347] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A low-temperature liquid-phase molecular sieve dechlorination agent, characterized in that: The raw material composition of the low-temperature liquid-phase molecular sieve dechlorination agent includes phosphorus-modified fine-crystallized molecular sieve, phytic acid-modified polyhydroxy polymer complexed metal ions, active silicon-coated nano-ceramic powder, oligoglycerol, pseudoboehmite, potassium silicate aqueous solution, and deionized water; The oligoglycerol is one of diglycerol, tetraglycerol, hexaglycerol, octaglycerol, decaglycerol, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio; For the phosphorus-modified fine-crystallized molecular sieve, its preparation method is: Add deionized water and phytate powder into a mixing kettle, stir vigorously to disperse evenly, then reduce the stirring rate and add a silicon source, an aluminum source, and hexamethylenediammonium hydroxide. After stirring into a gel, add a peroxide, continue stirring until the gel becomes milky white, then quickly transfer the milky white gel to a reaction kettle preheated to the crystallization temperature and equipped with a polytetrafluoroethylene inner lining. Maintain the crystallization temperature and carry out isothermal crystallization. After crystallization is completed, cool and discharge, filter and separate. The separated solid is washed, dried, and then placed in a muffle furnace for roasting. After roasting is completed, cool to room temperature to obtain the phosphorus-modified fine-crystallized molecular sieve; For the phytic acid-modified polyhydroxy polymer complexed metal ions, its preparation method is: Add a polyhydroxy polymer, a catalyst, and an organic solvent into a reaction kettle. Under nitrogen protection, stir and heat to the reaction temperature. After the raw materials in the kettle are completely dissolved, maintain the constant temperature and condensation reflux state, add an aqueous phytic acid solution, and continue stirring and reacting at a constant temperature. After the reaction is completed, cool to room temperature and filter and separate. The filtered liquid is added with anhydrous ethanol for recrystallization. The crystallized solid is washed with deionized water. The two steps of anhydrous ethanol recrystallization and deionized water washing are repeatedly cycled until the pH value of the liquid obtained by dissolving the product in the deionized water washing operation is neutral. Then add a water-soluble metal salt to the liquid with a neutral pH value, and let it stand for complexation adsorption. After the complexation adsorption is saturated, recrystallize with anhydrous ethanol again. The solid obtained by recrystallization is freeze-dried to obtain the phytic acid-modified polyhydroxy polymer complexed metal ions; For the active silicon-coated nano-ceramic powder, its preparation method is: Put nano-ceramic powder, deionized water, and sodium hexametaphosphate into a dispersion kettle, disperse strongly at the first dispersion rate until evenly dispersed, then raise the temperature and maintain the temperature at the reaction temperature, then reduce to the second dispersion rate and add an aqueous sodium metasilicate solution, and then dropwise add an aqueous sulfuric acid solution. Control the dropping rate to keep the pH value of the reaction system at 9-10.

5. After dropping is completed, stop dispersion and heating, let it stand for aging. After aging is completed, filter. The filtered solid is washed with water and dried to obtain the active silicon-coated nano-ceramic powder.

2. The low-temperature liquid-phase molecular sieve dechlorination agent according to claim 1, characterized in that: The phytate is one of copper phytate, calcium phytate, magnesium phytate, zinc phytate, nickel phytate, cobalt phytate, iron phytate, vanadium phytate, titanium phytate, a mixture composed of any two in any mass ratio, or a mixture composed of any two or more in any mass ratio; The silicon source is one of sodium silicate, potassium silicate, silica sol, tetraethyl orthosilicate, and fumed silica, a mixture composed of any two of them in any mass ratio, or a mixture composed of any two or more of them in any mass ratio; The aluminum source is one of aluminum isopropoxide, pseudo-boehmite, sodium meta-aluminate, and aluminum hydroxide, a mixture composed of any two of them in any mass ratio, or a mixture composed of any two or more of them in any mass ratio; The peroxide is one of calcium peroxide, magnesium peroxide, zinc peroxide, lithium peroxide, sodium peroxide, and potassium peroxide, a mixture composed of any two of them in any mass ratio, or a mixture composed of any two or more of them in any mass ratio; The mass ratio of deionized water, phytate powder, silicon source, aluminum source, hexamethylenediamine hydroxide, and peroxide is 120~430:10~45:50~150:40~130:20~50:1~8.

3. The low-temperature liquid-phase molecular sieve dechlorination agent according to claim 1, characterized in that: The polyhydroxy polymer is one of polyvinyl alcohol, starch, cellulose, and cellulose derivatives, a mixture composed of any two of them in any mass ratio, or a mixture composed of any two or more of them in any mass ratio; The catalyst is one of thiourea and sulfonamide or a mixture composed of the two in any mass ratio; The organic solvent is one of dimethyl sulfoxide, N,N-dimethylformamide, sulfolane, and N-methylpyrrolidone; The mass concentration of phytic acid in the aqueous phytic acid solution is 50~80 wt%; Among the water-soluble metal salts, the metal is one of copper, calcium, magnesium, zinc, nickel, cobalt, iron, vanadium, and titanium, or a combination of any two or more of them; The mass ratio of the polyhydroxy polymer, catalyst, organic solvent, and aqueous phytic acid solution is 20~130:5~13:200~600:10~40.

4. The low-temperature liquid-phase molecular sieve dechlorination agent according to claim 1, characterized in that: The nano-ceramic powder is one of nano-zirconia, nano-alumina, and nano-zirconium silicate; The particle size of the nano-ceramic powder is 10~100 nm; In the aqueous sodium metasilicate solution, the mass fraction of sodium metasilicate is 13~25 wt%; In the sulfuric acid aqueous solution, the mass fraction of sulfuric acid is 8~11 wt%; The mass ratio of the nano-ceramic powder, deionized water, sodium hexametaphosphate, aqueous sodium metasilicate solution, and sulfuric acid aqueous solution is 40~100:250~550:5~15:30~70:35~80.

5. A preparation method of the low-temperature liquid-phase molecular sieve dechlorination agent according to claim 1, characterized in that: The preparation method of the low-temperature liquid-phase molecular sieve dechlorination agent includes preparing a slurry, extrusion molding, and curing and roasting; For the preparation of the slurry, the phosphorus-modified fine-crystallized molecular sieve, the active-silica-coated nano-ceramic powder, and deionized water are added to a double planetary mixer. While controlling the stirring rate at 80 - 120 revolutions per minute and the dispersion rate at 7000 - 9500 revolutions per minute, after stirring and dispersing for 5 - 7 hours, the phytic acid-modified polyhydroxy polymer complex metal ions, oligoglycerol, pseudo-boehmite, and potassium silicate aqueous solution are added, and stirring and dispersing are continued for 6 - 10 hours to obtain a paste-like slurry.

6. The preparation method of the low-temperature liquid-phase molecular sieve dechlorination agent according to claim 5, characterized in that: For the extrusion molding, the slurry is injected into an extruder, and the screw speed and the diameter of the die orifice of the head are adjusted so that the diameter of the extruded nearly circular particles is 5 - 14 mm to obtain the original dechlorination agent particles.

7. The preparation method of the low-temperature liquid-phase molecular sieve dechlorination agent according to claim 6, characterized in that: For the curing and calcination, the original dechlorination agent particles are placed in a vacuum drying oven and dried at 45 - 70 °C for 7 - 15 hours, then placed in a room-temperature environment with a relative air humidity of 45 - 60% and allowed to stand and age for 12 - 24 hours. Then, they are transferred to a muffle furnace and heated from room temperature to 120 - 160 °C at a heating rate of 0.5 - 3 °C / min, and cured at a constant temperature for 6 - 10 hours. Then, the temperature is raised to 450 - 580 °C at a heating rate of 2 - 4 °C / min, and calcined at a constant temperature for 12 - 20 hours. Then, it is naturally cooled to room temperature, and the low-temperature liquid-phase molecular sieve dechlorination agent is obtained after discharging.

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