Catalyst for catalyzing bleaching of alkaline hydrogen peroxide paper pulp and application of catalyst
By grafting cyano and ammonia oxime groups onto wood-based materials and loading cobalt ions, a stable catalyst was prepared, solving the stability and environmental protection problems of existing catalysts. This resulted in improved pulp brightness and cobalt ion recovery, achieving an environmentally friendly and efficient pulp bleaching effect.
Patent Information
- Application Number
- CN202511470831.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2026-03-03
AI Technical Summary
Existing alkaline hydrogen peroxide pulp bleaching catalysts suffer from poor stability, low economic efficiency, and insufficient environmental friendliness, especially the easy loss of Co ions, which poses an environmental risk.
The catalyst was prepared by cyanoethylation, modification with a cyanoamine oxime group, and cobalt ion loading. By grafting cyano and cyanoamine oxime groups onto the surface of wood-based materials and combining them with cobalt ion adsorption, a stable complex was formed, enabling the recycling of the catalyst.
It improves pulp whiteness, enables the recycling of cobalt ions, reduces the risk of heavy metal emissions, and ensures pulp quality and environmental friendliness.
Smart Images
Figure CN121588903A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pulp bleaching and heavy metal recycling technology, and specifically relates to a catalyst for catalyzing alkaline hydrogen peroxide pulp bleaching and its application. Background Technology
[0002] In the current papermaking industry, alkaline hydrogen peroxide bleaching is a commonly used whitening process, and its efficiency largely depends on the stability and effective activation of hydrogen peroxide. While there are precedents for using homogeneous cobalt as a catalyst in existing technologies, the following problems exist: I. Catalyst stability issues: Co ligands are prone to alkaline hydrolysis to generate cobalt hydroxide.
[0003] II. Economic issues of catalysts: Existing bleaching catalysts have high preparation costs and are difficult to recycle and reuse, making it difficult to maximize economic benefits and limiting their industrial application.
[0004] III. Environmental friendliness of catalysts: Existing catalysts have poor stability under strongly alkaline conditions, which leads to the loss of Co ions, which are transferred to wastewater, posing an environmental risk. Summary of the Invention
[0005] To overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a method for preparing a catalyst for catalytic alkaline hydrogen peroxide pulp bleaching. The preparation method includes steps such as cyanoethylation, modification with a metallo-oxime group, and cobalt ion loading.
[0006] Another object of the present invention is to provide a catalyst for catalytic alkaline hydrogen peroxide pulp bleaching prepared by the above method.
[0007] Another object of the present invention is to provide the application of the above-mentioned catalyst for catalyzing alkaline hydrogen peroxide pulp bleaching in alkaline hydrogen peroxide pulp bleaching.
[0008] The objective of this invention is achieved through the following solution: A method for preparing a catalyst for catalytic alkaline hydrogen peroxide pulp bleaching includes the following steps: (1) React wood-based materials with acrylonitrile to graft cyano groups onto their surface; (2) The cyanided wood-based material is added to a mixed aqueous solution of hydroxylamine hydrochloride and sodium hydroxide to react and graft a methylamine oxime group onto its surface to obtain a wood-based material modified with a methylamine oxime group. (3) The wood-based material modified with the amylopyridine group is soaked in a solution containing cobalt salt to carry out an adsorption reaction, thereby obtaining a catalyst for catalyzing alkaline hydrogen peroxide pulp bleaching.
[0009] The wood-based material described in step (1) is preferably pretreated by cutting, drying and other processes before use.
[0010] The wood-based material mentioned in step (1) is one of the woods used for pulping and papermaking, such as balsa wood, pine wood, linden wood, fir wood, birch wood, poplar wood, and eucalyptus wood, with balsa wood being the preferred balsa wood-based material.
[0011] In step (1), the amount of wood-based material and acrylonitrile used is such that 1g of wood-based material is immersed in 25-50mL of acrylonitrile for reaction; in step (1), sodium hydroxide aqueous solution can also be added to promote the reaction, and the amount of sodium hydroxide aqueous solution used is such that 0.1-2mL of 10wt% sodium hydroxide aqueous solution is added for 1g of wood-based material.
[0012] The reaction described in step (1) refers to the reaction at 15~35℃ for 3~10h.
[0013] After the reaction in step (1) is completed, a purification step is also included, which specifically includes the following steps: neutralizing the mixture after the reaction with acid, and then washing and drying to obtain the purified cyanided wood-based material.
[0014] In step (2), the amount of cyaninated wood-based material, hydroxylamine hydrochloride, and sodium hydroxide is such that every 1g of cyaninated wood-based material is immersed in a mixed aqueous solution of 20-100mL of hydroxylamine hydrochloride and sodium hydroxide. The molar ratio of hydroxylamine hydrochloride to sodium hydroxide in the mixed aqueous solution is 1:1, and the concentration of hydroxylamine hydrochloride in the mixed aqueous solution is 1-5mol / L.
[0015] The reaction described in step (2) refers to a reaction at 50-90℃ for 3-12 hours. Preferably, the wood should be soaked at room temperature for 0.5-2 hours before the reaction to ensure the reaction solution fully penetrates the wood.
[0016] After the reaction is completed in step (2), purification steps such as washing and drying are also included.
[0017] The cobalt salt-containing solution mentioned in step (3) refers to one of the cobalt chloride aqueous solution and the cobalt nitrate aqueous solution, and the cobalt ion concentration in the cobalt salt-containing solution is 0.1~1 mol / L.
[0018] The amounts of the wood-based material modified with the amylopectin group and the solution containing cobalt salt described in step (3) are such that each 1g of wood-based material modified with the amylopectin group is immersed in 20~100mL of solution containing cobalt salt.
[0019] The cobalt salt solution mentioned in step (3) can also be used to bleach wastewater after alkaline hydrogen peroxide pulp bleaching, which is a catalyst of the present invention.
[0020] The adsorption reaction described in step (3) refers to soaking and adsorption at 15~35℃ for 12~72h. After the reaction is completed, purification steps such as washing and drying are also included.
[0021] A catalyst for catalytic alkaline hydrogen peroxide pulp bleaching prepared by the above method.
[0022] The above-mentioned catalyst for catalytic alkaline hydrogen peroxide pulp bleaching is applied in catalytic alkaline hydrogen peroxide pulp bleaching.
[0023] A process for catalytic alkaline hydrogen peroxide pulp bleaching includes the following steps: adding the above-mentioned catalyst for catalytic alkaline hydrogen peroxide pulp bleaching to alkaline pulp, mixing evenly, adding an aqueous hydrogen peroxide solution, and then carrying out the bleaching reaction.
[0024] The alkaline pulp has a pH of 9-11 and a concentration of 8%-12%. The amount of catalyst used in the catalytic alkaline hydrogen peroxide pulp bleaching is 5-25 wt% of the oven-dry pulp mass; the concentration of the hydrogen peroxide aqueous solution is 30%-35%, and the amount of hydrogen peroxide in the hydrogen peroxide aqueous solution is 1-5 wt% of the oven-dry pulp mass.
[0025] The bleaching reaction refers to a reaction at 70~90℃ for 0.5~2 hours.
[0026] A viscosity protectant may also be added to the bleaching reaction, preferably at least one of magnesium sulfate and sodium silicate.
[0027] The bleaching reaction is completed and cobalt ion recovery is also included. The specific steps include the following steps: separating the mixture after the bleaching reaction to obtain pulp and bleaching wastewater, adding the wood-based material modified with a amine oxime group prepared in step (2) to the bleaching wastewater, mixing it thoroughly and then adsorbing and recovering it, and then washing and drying to obtain the catalyst for catalyzing alkaline hydrogen peroxide pulp bleaching.
[0028] The amount of the wood-based material modified with a methylamine oxime group prepared in step (2) added to the bleaching wastewater is 1~2g of the wood-based material modified with a methylamine oxime group prepared in step (2) per 1L of bleaching wastewater. The adsorption and recovery refers to soaking and adsorbing at 15~35℃ for 12~72h.
[0029] The modified wood catalyst loaded with cobalt ions, which was adsorbed and recovered, was reused for pulp bleaching according to the above-described pulp bleaching method. This invention proposes a cobalt ion recycling mechanism. By re-adsorbing cobalt ions from wastewater through wood modified with amine oxime, the recycling of cobalt ions not only improves the service life and economic efficiency of the catalyst, but also effectively prevents the environmental risks of heavy metal emissions, achieving the dual goals of environmental protection and efficient pulp bleaching.
[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) Raw materials are readily available and the process is easy to implement; (2) Significantly improves pulp brightness. Using cobalt oxime wood-based catalyst to catalyze alkaline hydrogen peroxide pulp bleaching can increase the ISO brightness of pulp in the hydrogen peroxide bleaching stage by 25% to 30%. (3) Metal recovery is simple, no pH adjustment is required, and the cobalt ion recovery rate reaches more than 85%; (3) The catalyst and adsorbent will not damage the pulp fiber structure and there are no impurities left, thus ensuring the quality of the pulp; (4) The bleaching process produces no pollution and is environmentally friendly. Attached Figure Description
[0031] Figure 1 ISO whiteness of pulp for different bleaching methods.
[0032] Figure 2 The curve showing the change in cobalt ion concentration in bleaching wastewater over adsorption time in Example 2.
[0033] Figure 3 XRD pattern of the catalyst prepared in Example 1.
[0034] Figure 4 SEM images of the fiber structures of pulp bleached with catalyst in Example 2 (left image) and bleached without catalyst in Comparative Example 1 (right image). Detailed Implementation
[0035] The present invention will be further explained below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.
[0036] All raw materials used in the examples are conventional raw materials and commercially available products, and all equipment used is conventional equipment.
[0037] All pulp concentrations mentioned in the examples are by weight percentage. The amounts of reagents used in bleaching are all by weight percentage relative to oven-dry pulp.
[0038] Example 1: Catalyst Preparation 1. Cyanoethylation: 1 g of natural balsa wood chips were added to 36 mL of acrylonitrile, along with 1 mL of a 10% (w / w) sodium hydroxide aqueous solution. The cyanoethylation reaction was carried out at room temperature (25±2℃) with magnetic stirring for 3 h. After the reaction was complete, the mixture was neutralized with 1% (w / w) acetic acid solution (10 mL), and then the cyanoethylated wood was thoroughly washed with ultrapure water. The cyanoethylated wood solid sample was obtained after freeze-drying.
[0039] 2. Modification with a methylamine oxime group: The oxime reaction was carried out in a mixed aqueous solution containing 1.725M hydroxylamine hydrochloride and 1.725M sodium hydroxide. 1g of cyanoethylated wood was immersed in 50mL of the mixed solution at room temperature for 2 hours to ensure thorough wetting of the wood. The oxime reaction was then carried out at 70℃ with stirring for 3 hours. After the reaction, the solid sample was thoroughly washed with ultrapure water and freeze-dried to obtain a methylamine oxime-modified wood solid sample.
[0040] 3. Cobalt ion loading: 1g of the metallo-oxime group-modified wood prepared in step 2 was loaded into 50mL of a Co solution with a metal ion concentration of 0.2mol / L. 2+ The sample was soaked in the solution for 24 hours. Repeated shaking on a shaker brought the adsorption to near equilibrium. The resulting sample was washed three times with deionized water. After freeze-drying, a wood-based catalyst loaded with cobalt ions was obtained.
[0041] Example 2: Pulp bleaching 1. Pulp preparation: Take sulfate eucalyptus pulp (brightness 58.5% ISO, viscosity 669 mL / g), adjust the pulp consistency to 10%, and place it in a polyethylene plastic bag and put it in a water bath for hydrogen peroxide bleaching.
[0042] 2. Catalyst addition: The catalyst prepared in Example 1 above was added to the pulp at a ratio of 25 wt% (based on oven-dry pulp), along with 0.05 wt% (based on oven-dry pulp) magnesium sulfate and 1.5 wt% (based on oven-dry pulp) sodium silicate. The mixture was thoroughly mixed, and the pH was adjusted to 10 using dilute sulfuric acid and sodium hydroxide solution.
[0043] 3. Hydrogen peroxide addition: Add 5 wt% (hydrogen peroxide solute based on oven-dry pulp) of an aqueous solution of hydrogen peroxide (hydrogen peroxide concentration of 30 wt%) to the pulp.
[0044] 4. Bleaching reaction: React the pulp at 70℃ for 60 min.
[0045] 5. Post-treatment: After the reaction is complete, the pulp is washed with deionized water until neutral, and the pulp brightness is measured. The brightness of the bleached pulp is 73.4% ISO.
[0046] Comparative Example 1: This comparative example is basically the same as that described in Example 2, except that no cobalt-based wood-based catalyst was added during the bleaching process. All other conditions were the same, and the resulting bleached pulp had a whiteness of 68.5% ISO.
[0047] Comparative Example 2: This comparative example is basically the same as Example 2, except that the pulp preparation and catalyst addition steps in the bleaching process are different. Specifically, the pulp preparation uses oven-dried pulp directly, and the catalyst addition involves directly adding the oven-dried pulp to an EDTA-Co aqueous solution. At this point, the pulp concentration is 10%, and EDTA-Co is used as the catalyst at a concentration of 0.1 mmol / L. All other conditions are the same, and the resulting bleached pulp has a brightness of 70.6% ISO. The EDTA-Co is obtained by mixing EDTA and cobalt chloride in a molar ratio of 4:1 at 25°C for 1 hour.
[0048] Example 3: Cobalt Ion Recovery Method 1. Bleaching wastewater: After the bleaching reaction in Example 2 is completed, the pulp and bleaching wastewater are separated using a Buchner funnel. The bleaching wastewater after filtration has a cobalt ion concentration of 5.7 mg / L.
[0049] 2. Adsorbent addition: After the hydrogen peroxide has completely decomposed, the amylopectin-modified wood-based material adsorbent prepared in step (2) of Example 1 is added to the bleaching wastewater at a dosage of 1 g / L and mixed thoroughly.
[0050] 3. Adsorption and Recovery: Adsorption was performed at room temperature (25℃) for 12 hours. Repeated shaking on a shaker brought the adsorption to near equilibrium. After adsorption, the cobalt ion concentration in the bleaching wastewater was 0.8 mg / L, and the Co ion recovery rate reached 86%. The obtained sample was washed three times with deionized water. After freeze-drying, a wood-based catalyst loaded with cobalt ions was obtained.
[0051] 4. Recycling: The modified wood catalyst loaded with cobalt ions that was adsorbed and recovered was reused for pulp bleaching in place of the catalyst in Example 2, according to the pulp bleaching method in Example 2 (brightness 58.5% ISO, viscosity 669 mL / g). All other parameters were the same as in Example 2. The brightness of the resulting bleached pulp was 72.5% ISO.
[0052] Example 4: 1. Cyanoethylation: 1 g of poplar wood chips were added to 50 mL of acrylonitrile, along with 2 mL of a 10% (w / w) sodium hydroxide aqueous solution. The cyanoethylation reaction was carried out at 35 °C with magnetic stirring for 10 h. After the reaction was complete, the mixture was neutralized with 1% (w / w) acetic acid solution (10 mL), and then the cyanoethylated wood was thoroughly washed with ultrapure water. The cyanoethylated wood solid sample was obtained after freeze-drying.
[0053] 2. Modification with a methylamine oxime group: The oxime reaction was carried out in a mixed aqueous solution containing 5M hydroxylamine hydrochloride and 5M sodium hydroxide. 1g of cyanoethylated wood was immersed in 20mL of the mixed solution at room temperature for 2 hours to ensure thorough wetting of the wood. The oxime reaction was then carried out at 90℃ with stirring for 10 hours. After the reaction, the solid sample was thoroughly washed with ultrapure water and freeze-dried to obtain a methylamine oxime-modified wood solid sample.
[0054] 3. Cobalt ion loading: 1g of the metallo-oxime group-modified wood prepared in step 2 was loaded into 20mL of a Co solution with a metal ion concentration of 1mol / L. 2+ The sample was soaked in the solution for 72 hours. Repeated shaking on a shaker brought the adsorption to near equilibrium. The resulting sample was washed three times with deionized water. After freeze-drying, a wood-based catalyst loaded with cobalt ions was obtained.
[0055] Example 5: Pulp bleaching 1. Pulp preparation: Take sulfate eucalyptus pulp (brightness 58.5% ISO, viscosity 669 mL / g), adjust the pulp consistency to 10%, and place it in a polyethylene plastic bag and a water bath for hydrogen peroxide bleaching.
[0056] 2. Catalyst addition: The catalyst prepared in Example 4 above was added to the pulp at a ratio of 5 wt% (based on oven-dry pulp), along with 0.05 wt% (based on oven-dry pulp) magnesium sulfate and 1.5 wt% (based on oven-dry pulp) sodium silicate. The mixture was thoroughly mixed, and the pH was adjusted to 11 using dilute sulfuric acid and sodium hydroxide solution.
[0057] 3. Hydrogen peroxide addition: Add 2 wt% (hydrogen peroxide solute based on oven-dry pulp) of an aqueous solution of hydrogen peroxide (hydrogen peroxide concentration of 30 wt%) to the pulp.
[0058] 4. Bleaching reaction: React the pulp at 90℃ for 120 min.
[0059] 5. Post-treatment: After the reaction is complete, the pulp is washed with deionized water until neutral, and the pulp brightness is measured. The brightness of the bleached pulp is 72.6% ISO.
[0060] Example 6: Cobalt Ion Recovery 1. Bleaching wastewater: After the bleaching reaction in Example 5 is completed, the pulp and bleaching wastewater are separated using a Buchner funnel, and the separated bleaching wastewater is filtered.
[0061] 2. Adsorbent addition: After the hydrogen peroxide has completely decomposed, the amylopectin-modified wood-based material adsorbent prepared in step (2) of Example 1 is added to the bleaching wastewater at a dosage of 1 g / L and mixed thoroughly.
[0062] 3. Adsorption and Recovery: Adsorption was carried out at room temperature (25℃) for 60 h. Repeated shaking on a shaker brought the adsorption to near equilibrium. After adsorption, the cobalt ion concentration in the bleaching wastewater was 10 mg / L, and the Co ion recovery rate reached 85%. The obtained sample was washed three times with deionized water. After freeze-drying, a wood-based catalyst loaded with cobalt ions was obtained.
[0063] 4. Recycling: The modified wood catalyst loaded with cobalt ions that was adsorbed and recovered was reused for pulp bleaching in place of the catalyst in Example 5, according to the pulp bleaching method in Example 5 (brightness 58.5% ISO, viscosity 669 mL / g). All other parameters were the same as in Example 5. The brightness of the resulting bleached pulp was 72.1% ISO.
[0064] Figure 1 The ISO brightness of pulps bleached using different methods is shown. It can be seen that adding the catalyst increased pulp brightness by 49%, and by 23% compared to EDTA-Co. In Example 3, even after cobalt ion recycling, pulp brightness was still increased by 40%.
[0065] Figure 2 The curve showing the change in cobalt ion concentration in the bleaching wastewater over adsorption time in Example 3 is shown. It can be seen that the cobalt ion adsorption recovery rate reaches 86%, indicating a good recovery effect.
[0066] Figure 3 The image shows the XDR spectrum of the catalyst used in Example 1. It can be seen that no Co crystal diffraction signal appeared after chemical modification and metal adsorption, indicating that Co exists in ionic form. Cobalt ions form stable complexes with the metallo-oxime groups, which can reduce the concentration of free cobalt ions and convert them into chelated cobalt ions, preventing cobalt ions from precipitating and thus enabling them to play a catalytic role.
[0067] Figure 4 SEM images of the fiber structure of pulp bleached with and without catalyst are shown. It can be seen that after using the catalyst, the pulp surface fibers are relatively smooth with no obvious fibrillation, ensuring pulp quality.
[0068] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing a catalyst for catalytic alkaline hydrogen peroxide pulp bleaching, characterized in that... Includes the following steps: (1) React wood-based materials with acrylonitrile to graft cyano groups onto their surface; (2) The cyanided wood-based material is added to a mixed aqueous solution of hydroxylamine hydrochloride and sodium hydroxide to react and graft a methylamine oxime group onto its surface to obtain a wood-based material modified with a methylamine oxime group. (3) The wood-based material modified with the amylopyridine group is soaked in a solution containing cobalt salt to carry out an adsorption reaction, thereby obtaining a catalyst for catalyzing alkaline hydrogen peroxide pulp bleaching.
2. The method for preparing the catalyst for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 1, characterized in that: The wood-based material mentioned in step (1) is one of the following: balsa wood, pine wood, linden wood, fir wood, birch wood, poplar wood, and eucalyptus wood; The amount of wood-based material and acrylonitrile used in step (1) is such that 1g of wood-based material corresponds to immersion in 25~50mL of acrylonitrile for reaction; sodium hydroxide aqueous solution is also added in step (1) to promote the reaction, and the amount of sodium hydroxide aqueous solution used is such that 0.1~2mL of 10wt% sodium hydroxide aqueous solution is added for every 1g of wood-based material. The reaction described in step (1) refers to the reaction at 15~35℃ for 3~10h.
3. The method for preparing the catalyst for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 1, characterized in that: In step (2), the amount of cyaninated wood-based material, hydroxylamine hydrochloride, and sodium hydroxide is such that every 1g of cyaninated wood-based material is immersed in 20-100mL of a mixed aqueous solution of hydroxylamine hydrochloride and sodium hydroxide, the molar ratio of hydroxylamine hydrochloride to sodium hydroxide in the mixed aqueous solution is 1:1, and the concentration of hydroxylamine hydrochloride in the mixed aqueous solution is 1-5mol / L. The reaction described in step (2) refers to a reaction at 50~90℃ for 3~12 hours. Before the reaction, the wood is soaked at room temperature for 0.5~2 hours to allow the reaction solution to fully wet the wood.
4. The method for preparing the catalyst for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 1, characterized in that: The cobalt salt-containing solution mentioned in step (3) refers to one of cobalt chloride aqueous solution and cobalt nitrate aqueous solution, and the cobalt ion concentration in the cobalt salt-containing solution is 0.1~1mol / L; the amount of the amylopyridine-modified wood-based material and the cobalt salt-containing solution mentioned in step (3) is such that 1g of amylopyridine-modified wood-based material is immersed in 20~100mL of the cobalt salt-containing solution; The adsorption reaction mentioned in step (3) refers to soaking and adsorbing at 15~35℃ for 12~72h.
5. A catalyst for catalytic alkaline hydrogen peroxide pulp bleaching prepared by the method according to any one of claims 1-4.
6. The application of the catalyst for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 5 in catalytic alkaline hydrogen peroxide pulp bleaching.
7. A process for catalytic alkaline hydrogen peroxide pulp bleaching, characterized in that... Includes the following steps: The catalyst for bleaching alkaline hydrogen peroxide pulp as described in claim 5 is added to alkaline pulp, mixed evenly, and then an aqueous solution of hydrogen peroxide is added, followed by a bleaching reaction.
8. The process for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 7, characterized in that: The alkaline pulp has a pH of 9-11 and a concentration of 8%-12%. The amount of catalyst used in the catalytic alkaline hydrogen peroxide pulp bleaching is 5-25 wt% of the oven-dry pulp mass; the concentration of the hydrogen peroxide aqueous solution is 30%-35%, and the amount of hydrogen peroxide in the hydrogen peroxide aqueous solution is 1-5 wt% of the oven-dry pulp mass; The bleaching reaction refers to a reaction at 70~90℃ for 0.5~2 hours.
9. The process for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 8, characterized in that: The bleaching reaction is completed and cobalt ion recovery is also included. The specific steps include the following steps: separating the mixture after the bleaching reaction to obtain pulp and bleaching wastewater; adding the wood-based material modified with a methylamine oxime group prepared in step (2) of the preparation method according to any one of claims 1-4 to the bleaching wastewater; mixing thoroughly and then adsorbing and recovering the mixture; and then washing and drying to obtain the catalyst for catalyzing alkaline hydrogen peroxide pulp bleaching. The obtained catalyst is then used to catalyze alkaline hydrogen peroxide pulp bleaching.
10. The process for catalytic alkaline hydrogen peroxide pulp bleaching according to claim 9, characterized in that: The amount of wood-based material modified with a methylamine oxime group prepared in step (2) added to the bleaching wastewater is 1~2g of wood-based material modified with a methylamine oxime group prepared in step (2) per 1L of bleaching wastewater; the adsorption and recovery refers to soaking and adsorbing at 15~35℃ for 12~72h.