A plastic-based solid acid catalyst and a method for directional catalytic depolymerization of biomass.

Abstract

This invention discloses a plastic-based solid acid catalyst and a method for the directional catalytic depolymerization of biomass. The preparation method of the plastic-based solid acid catalyst includes the following steps: pretreated waste plastic is added to a reaction vessel with concentrated sulfuric acid for sulfonation. The waste plastic is selected from one or more of polyethylene, polypropylene, polyvinyl chloride, and polystyrene. After the reaction is completed, the obtained solid product and reaction solution are separated. The solid product is washed and dried to obtain the plastic-based solid acid catalyst. This invention utilizes the difference in the ease of hydrolysis between cellulose and hemicellulose in biomass. First, under relatively mild reaction conditions, solid acid is used to fully hydrolyze the hemicellulose component in the biomass raw material. Then, the hydrolysate is filtered out, and water is added again as a reaction solution for further hydrolyzing cellulose, increasing the reaction intensity and fully hydrolyzing the cellulose in the biomass raw material. Through two-step hydrolysis reactions, hydrolysates rich in xylose and glucose are obtained respectively.

Description

Technical fields:

[0001] This invention relates to the field of waste plastic recycling technology, specifically to a plastic-based solid acid catalyst and a method for directional catalytic depolymerization of biomass. Background technology:

[0002] Fossil fuels, as a finite strategic resource, have fueled rapid economic and social development for a long time, but have also caused severe damage to the natural environment. Therefore, exploring and developing clean and efficient renewable energy sources has far-reaching practical significance.

[0003] Biomass energy refers to the energy generated by various organisms through photosynthesis. It is a form of energy stored in biomass in the form of solar energy and has always been one of the most important energy sources for human survival. It is the fourth largest energy source after coal, oil, and natural gas, holding a crucial position in the entire energy system. Fuel ethanol is one of the most widely used biomass-derived energy sources globally, and it can be produced through the catalytic conversion of biomass. Lignocellulosic biomass is an important type of biomass resource, composed of hemicellulose, cellulose, and lignin. Hemicellulose and cellulose in lignocellulosic biomass can be converted into fermentable sugars through fractional degradation, which can then be fermented by yeast to produce fuel ethanol. How to achieve the green, efficient, and low-energy-consumption directed depolymerization of lignocellulosic biomass raw materials to produce fermentable sugars is a key problem that urgently needs to be solved in the entire process technology.

[0004] Solid acid catalysts are important chemical catalysts widely used in various industries, but their application in the graded depolymerization process of lignocellulose biomass is still relatively limited. The inventors have previously developed several carbon-based solid acids, as disclosed in patents ZL201110126178.7, ZL201610624249.9, ZL201610623755.6, and CN108855135A. The carbon-based solid acid catalysts developed by the inventors exhibit good hemicellulose catalytic activity and xylose selectivity, enabling the directional depolymerization of hemicellulose to xylose in an aqueous phase. These catalysts are prepared from biomass and its derivatives through carbonization and sulfonation steps. However, currently prepared solid acid catalysts suffer from problems such as relatively simple active groups and poor framework stability. There is an urgent need to develop novel solid acid catalysts with richer active groups and more stable framework structures, enabling them to possess stronger lignocellulose depolymerization capabilities and reusability.

[0005] Waste plastics (mainly including polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polypropylene (PP), etc.) are produced in enormous quantities and are difficult to degrade. Currently, my country is the world's largest producer and consumer of plastics, requiring the disposal of 33 million tons of waste plastics annually. This need is becoming increasingly urgent, especially with the development of express delivery and food delivery services. Similarly, waste plastics, as an important renewable resource, have high recycling value. They are high-molecular-weight compounds with a cyclic carbon molecular formula and a relatively dense structure. In addition to a carbon skeleton, they often contain other functional groups, such as chlorine-containing functional groups (PVC). Therefore, using waste plastics to prepare solid acid catalysts can effectively avoid the drawbacks of applying carbon-based solid acids to the depolymerization of lignocellulose. Furthermore, the recycling of waste plastics aligns with the dual carbon goals and is of great significance for expanding the high-value utilization of waste plastics. CN112156811A discloses the use of chloromethyl polystyrene to dismantle biomass with good results, but the raw materials are expensive, and the resulting solid acid has a relatively singular active group, making it unsuitable for different types of biomass such as grasses, softwood, and hardwood. CN114590881A discloses a method for hydrolyzing and degrading macrolide antibiotics in wastewater using a solid acid catalyst. However, this method suffers from the problem of having only one active group, and its fabrication process requires a swelling step, making it relatively cumbersome. This issue urgently needs to be addressed. Summary of the Invention:

[0006] This invention solves the problems existing in the prior art and provides a plastic-based solid acid catalyst and a method for directional catalytic depolymerization of biomass. This invention utilizes the different hydrolysis difficulties of cellulose and hemicellulose in biomass. First, under relatively mild reaction conditions, solid acid is used to fully hydrolyze the hemicellulose component in the biomass raw material. Then, the hydrolysate is filtered out, and water is added again as a reaction solution for further hydrolysis of cellulose to increase the reaction intensity and fully hydrolyze the cellulose in the biomass raw material. Through the two-step hydrolysis reaction, hydrolysates rich in xylose and glucose are obtained respectively.

[0007] The purpose of this invention is to provide a method for preparing a plastic-based solid acid catalyst, comprising the following steps: adding pretreated waste plastic and concentrated sulfuric acid into a reaction vessel for sulfonation reaction, wherein the waste plastic is selected from two or more of polystyrene, polyethylene, polypropylene and polyvinyl chloride; after the reaction is completed, separating the obtained solid product and reaction liquid; and washing and drying the solid product to obtain a plastic-based solid acid catalyst containing groups such as -SO3H, -Cl, -OH and -COOH.

[0008] The reaction vessel proposed in this invention is a pressure reactor with a polytetrafluoroethylene liner; the concentrated sulfuric acid used in the sulfonation process of waste plastic and concentrated sulfuric acid can be reused after recycling, and the concentrated sulfuric acid (98%, w / w) can be used 4-5 times.

[0009] Preferably, the waste plastic is a mixture of polystyrene with polyethylene, polypropylene, or polyvinyl chloride.

[0010] Further preferred, the mass ratio of polystyrene to polyethylene, polypropylene, or polyvinyl chloride is 1:1-5.

[0011] Different types of waste plastics can be sulfonated separately after being mixed with concentrated sulfuric acid, or they can be mixed in a certain mass ratio and then sulfonated with concentrated sulfuric acid. After the sulfonation reaction is completed, the mixture is cooled, the concentrated sulfuric acid is recovered, and the solid powder is separated. The solid powder is then washed with deionized water until the washing solution is neutral. Finally, the solid powder is dried in an oven at 105°C for 12 hours and collected to obtain a plastic-based solid acid catalyst for later use.

[0012] Preferably, the pretreatment steps for the pretreated waste plastic are: washing and drying the waste plastic, then crushing and screening it, controlling the screening mesh size to be between 100 and 150 mesh, and then washing and drying it again to obtain waste plastic powder.

[0013] Preferably, the mass-to-volume ratio of the total mass of waste plastics to concentrated sulfuric acid is 1:5-20 kg / L, the sulfonation reaction temperature is 120℃-180℃, and the reaction time is 0.5-6 h.

[0014] This invention also protects the plastic-based solid acid catalyst obtained by the above preparation method.

[0015] This invention also protects a method for the directional catalytic depolymerization of biomass using a plastic-based solid acid catalyst, comprising the following steps:

[0016] (1) Catalyst hydrolysis pretreatment: The wood fiber raw material is mixed with the plastic-based solid acid catalyst and water is added as a solvent in the reaction vessel for heating reaction. After the reaction is completed, the first solid residue and the pretreatment liquid containing xylose are separated.

[0017] (2) Second-order hydrolysis: Water is added to the reactor of the first solid residue obtained in step (1), and the reaction is heated again. After the reaction is completed, the second solid residue and the second hydrolysate containing glucose are separated.

[0018] This invention is the first to utilize inexpensive waste plastics to prepare a solid acid catalyst containing multiple functional groups such as sulfonic acid groups through a one-step sulfonation process. When this catalyst is applied to biomass sugar production, the target products xylose and glucose are obtained in high yield.

[0019] The particle size of the wood fiber raw material is 0.1-1.0 mm. The wood fiber raw material is selected from one or more of agricultural waste, wood processing waste and energy herbaceous plants. Agricultural waste includes corn cob, wheat straw and sugarcane bagasse. Wood processing waste includes poplar sawdust, eucalyptus sawdust and pine sawdust. Energy herbaceous plants include Napier grass and Miscanthus sinensis.

[0020] The first solid residue includes lignocellulose solid residue and plastic-based solid acid catalyst, and the second solid residue includes a small amount of lignocellulose residue and plastic-based solid acid catalyst. The amount of water added in step (2) is the same as in step (1).

[0021] Preferably, the mass ratio of the wood fiber raw material to the plastic-based solid acid catalyst in step (1) is 1-4:1, and the mass-volume ratio of the wood fiber raw material to water is 1:10-40 kg / L.

[0022] Preferably, the heating reaction conditions in step (1) are: reaction temperature 110℃-160℃, reaction time 10-180min.

[0023] Preferably, the heating reaction conditions in step (2) are: reaction temperature 160℃-190℃, reaction time 1-6h.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. This invention proposes a new approach to the recycling of waste plastics: using waste plastics to prepare plastic-based solid acid catalysts for the hydrolysis of lignocellulose biomass.

[0026] 2. The plastic-based solid acid catalyst prepared by this invention has high catalytic activity and selectivity, and can directionally depolymerize hemicellulose and cellulose components in lignocellulose under different conditions in an aqueous system to prepare xylose and glucose.

[0027] 3. The plastic-based solid acid catalyst prepared by this invention has the characteristics of being non-corrosive, having good stability, high selectivity, and being recyclable and reusable. It is not only non-corrosive to the pretreatment reaction device, but also does not introduce other soluble impurities into the hydrolysate after the reaction except for the target product, thus minimizing the pressure on the subsequent environment.

[0028] 4. The process of directional catalytic depolymerization of biomass proposed in this invention involves a two-step hydrothermal reaction using a plastic-based solid acid catalyst to directionally depolymerize the hemicellulose and cellulose components into the corresponding products. Attached image description:

[0029] Figure 1 This is the solid-state NMR spectrum of the plastic-based solid acid catalyst SPS150-3 obtained in Example 1;

[0030] Figure 2 The images show SEM images of the mixed plastic-based solid acid catalyst obtained in Example 2 before and after sulfonation. The left side shows polystyrene powder (PS) and polyvinyl chloride powder (PVC), and the right side shows the two types of particles obtained after sulfonation.

[0031] Figure 3 This is the solid-state NMR spectrum of the plastic-based solid acid catalyst SPVC160-2 obtained in Example 4. Detailed implementation method:

[0032] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0033] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention. Unless otherwise specified, the experimental materials and reagents used herein are commercially available products conventionally available in this technical field.

[0034] Example 1

[0035] Waste polystyrene (PS) plastic was used as raw material. After washing and drying, the material was pulverized in a pulverizer, and the pulverized material was sieved to obtain 100-150 mesh particles as raw material. 0.1 kg of polystyrene powder was weighed and mixed with 1.5 L of concentrated sulfuric acid in a PTFE-lined reactor at a mass-to-volume ratio of 1:15 kg / L. The reactor was heated, and the reaction conditions were set as follows: sulfonation temperature 150℃ and sulfonation time 3 h. After the reaction was completed and cooled to room temperature, the solid product was separated from the concentrated sulfuric acid using a sintered glass funnel, and the concentrated sulfuric acid was recovered for later use. The solid particles were repeatedly washed with hot water (>80℃) until the filtrate was neutral. The washed solid acid particles were placed in an oven and dried at 105℃ for 12 h before being collected for later use; this is the plastic-based solid acid catalyst (SPS150-3).

[0036] The plastic-based solid acid catalysts obtained by the above methods were characterized by solid-state NMR, such as... Figure 1 As shown, the catalyst obtained after sulfonation retains the original molecular structure of polystyrene very well. The peak range on the right, between 25-60 ppm, describes the integrity of the main chain structure well. The peak range on the left, between 115-160 ppm, mainly describes the aromatic structure in polystyrene, which was not destroyed during sulfonation. The peak at 140 ppm mainly describes the structure with -SO3H groups on the benzene ring, indicating that the acidic groups that play a major catalytic role have been successfully introduced into the catalyst framework.

[0037] Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst obtained above was added to the reactor along with the poplar wood chips at a mass ratio of 1:2. Water was added to the hydrolysis reactor along with the poplar wood chips at a mass-to-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on. Timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-to-volume ratio of 1:20 (kg / L). Timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0038] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 85% (74% of which was pentose sugar, of which xylan accounted for 11%), and the cellulose retention rate in the solid residue was 89%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 87% (75% of which was hexose sugar, of which the content of dextran was 12%).

[0039] Example 2

[0040] Waste polystyrene (PS) and polyvinyl chloride (PVC) plastics were used as raw materials. After washing and drying, they were pulverized in a crusher, and the pulverized materials were sieved to obtain 100-150 mesh particles as raw materials. 0.075 kg of PVC powder and 0.025 kg of polystyrene powder, totaling 0.1 kg, were weighed and mixed with 1.5 L of concentrated sulfuric acid in a PTFE-lined reactor at a mass-to-volume ratio of 1:15 kg / L. The reactor was heated, and the reaction conditions were set as follows: sulfonation temperature 150℃ and sulfonation time 3 h. After the reaction was completed and cooled to room temperature, the solid product was separated from the concentrated sulfuric acid using a sintered glass funnel, and the concentrated sulfuric acid was recovered for later use. The solid particles were repeatedly washed with hot water (>80℃) until the filtrate was neutral. The washed solid acid particles were placed in an oven and dried at 105℃ for 12 h before being collected for later use; these are the plastic-based solid acid catalysts (SPS150-3 and SPVC150-3).

[0041] The plastic-based solid acid catalysts obtained by the above methods were characterized by SEM, such as... Figure 2 As shown, the surfaces of the raw materials polystyrene (PS) and polyvinyl chloride (PVC) on the left are relatively smooth, but after sulfonation, the surfaces of both raw materials become uneven and even cracked. This greatly increases the specific surface area of ​​the catalyst, which is beneficial to improving the mass transfer efficiency during the hydrolysis process.

[0042] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0043] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 93% (81% of which was pentose sugar, of which xylan accounted for 12%), and the cellulose retention rate in the solid residue was 85%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 91% (82% of which was hexose sugar, of which the content of dextran was 9%).

[0044] Comparative Example 1

[0045] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastics are 0.075 kg of polyethylene powder and 0.025 kg of polystyrene powder.

[0046] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0047] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 85% (77% of which was pentose sugar, of which xylan accounted for 13%), and the cellulose retention rate in the solid residue was 88%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 89% (79% of which was hexose sugar, of which the content of dextran was 15%).

[0048] Comparative Example 2

[0049] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastics are 0.075 kg of polypropylene powder and 0.025 kg of polystyrene powder.

[0050] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0051] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 87% (76% of which was pentose sugar, of which xylan accounted for 9%), and the cellulose retention rate in the solid residue was 90%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 89% (80% of which was hexose sugar, of which the content of dextran was 7%).

[0052] Comparative Example 3

[0053] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastics are 0.05 kg polyethylene powder, 0.025 kg polyvinyl chloride powder and 0.025 kg polystyrene powder.

[0054] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0055] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 91% (76% of which was pentose sugar, of which xylan accounted for 10%), and the cellulose retention rate in the solid residue was 84%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 90% (80% of which was hexose sugar, of which the content of dextran was 11%).

[0056] Comparative Example 4

[0057] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastics are 0.05 kg polyethylene powder, 0.025 kg polypropylene powder and 0.025 kg polystyrene powder.

[0058] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0059] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 88% (77% of which was pentose sugar, of which xylan accounted for 13%), and the cellulose retention rate in the solid residue was 89%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 88% (75% of which was hexose sugar, of which the content of dextran was 12%).

[0060] Comparative Example 5

[0061] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastics are 0.025 kg polyethylene powder, 0.025 kg polypropylene powder, 0.025 kg polyvinyl chloride powder and 0.025 kg polystyrene powder.

[0062] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0063] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 91% (80% of which was pentose sugar, of which xylan accounted for 11%), and the cellulose retention rate in the solid residue was 86%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 89% (80% of which was hexose sugar, of which the content of dextran was 10%).

[0064] Comparative Example 6

[0065] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastic is 0.1 kg of polyvinyl chloride powder.

[0066] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0067] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 71% (the yield of pentose sugars was 56%, of which xylan accounted for 19%), and the cellulose retention rate in the solid residue was 96%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 69% (the yield of hexose sugars was 55%, of which the content of dextran was 21%).

[0068] Example 3

[0069] Waste polyvinyl chloride (PVC) and waste polystyrene (PS) were used as raw materials. After washing and drying, they were pulverized in a crusher. The pulverized materials were then sieved to obtain 100-150 mesh particles as raw materials. 0.08 kg of PVC powder and 0.02 kg of polystyrene powder, totaling 0.1 kg, were weighed and reacted at a mass-to-volume ratio of 1:15 kg / L. The sulfonation temperature was 130℃, and the sulfonation time was 4 hours.

[0070] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Wheat straw with a particle size of 0.1-2 mm was selected as the lignocellulose raw material. The plastic-based solid acid catalyst and wheat straw were placed in the reactor at a mass ratio of 1:2. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:20 (kg / L). The heating device of the hydrolysis reactor was turned on. After the temperature inside the hydrolysis reactor reached 150°C, the timing was started. After 1 hour of reaction, the pretreated hydrolysate and solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of wheat straw, water was added to the hydrolysis reactor containing the solid residue at a mass-volume ratio of 1:15 (kg / L). After the temperature inside the hydrolysis reactor reached 170°C, the timing was started. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0071] The hydrolysates obtained from the two steps were analyzed. In the first hydrolysis stage, the yield of reducing sugars from hemicellulose was 87% (76% of pentose sugars, of which xylan accounted for 9%), and the cellulose retention rate in the solid residue was 89%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 86% (81% of hexose sugars, of which the content of dextran was 3%).

[0072] Example 4

[0073] A plastic-based catalyst (SPVC160-2) was prepared from waste polyvinyl chloride (PVC) raw material according to the steps in Example 1, with a sulfonation temperature of 160°C and a sulfonation time of 2 hours.

[0074] The plastic-based solid acid catalysts obtained by the above methods were characterized by SSNMR, such as... Figure 3 As shown, the catalyst obtained after sulfonation retains the original molecular structure of polyvinyl chloride very well, and the peak range on the right is between 25-60 ppm, which well describes the integrity of the main chain structure.

[0075] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Napier grass with a particle size of 0.1-2 mm was selected as the lignocellulose raw material. The plastic-based solid acid catalyst and Napier grass were placed in the reactor at a mass ratio of 1:2. Water was added to the hydrolysis reactor at a mass-to-volume ratio of 1:30 (kg / L). The heating device of the hydrolysis reactor was turned on, and timing was started after the temperature inside the hydrolysis reactor reached 150°C. After 2 hours of reaction, the hydrolysate and solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of Napier grass, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-to-volume ratio of 1:20 (kg / L). Timing was started after the temperature inside the hydrolysis reactor reached 170°C. After 4 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0076] Analysis of the hydrolysates obtained from the two steps showed that in the first hydrolysis stage, the yield of reducing sugars from hemicellulose was 76% (64% of which was pentose sugar, of which xylan accounted for 13%), and the cellulose retention rate in the solid residue was 90%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 80% (71% of which was hexose sugar, of which the content of dextran was 15%).

[0077] Example 5

[0078] Plastic-based solid acid catalysts were prepared using waste polypropylene (PP) and waste polystyrene (PS) as raw materials, following the method described in Example 2. The sulfonation temperature was 130°C and the sulfonation time was 4 hours.

[0079] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Wheat straw with a particle size of 0.1-2 mm was selected as the lignocellulose raw material. The plastic-based solid acid catalyst and wheat straw were placed in the reactor at a mass ratio of 1:2. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:20 (kg / L). The heating device of the hydrolysis reactor was turned on. After the temperature inside the hydrolysis reactor reached 150°C, the timing was started. After 1 hour of reaction, the hydrolysate and solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of wheat straw, water was added to the hydrolysis reactor containing the solid residue at a mass-volume ratio of 1:15 (kg / L). After the temperature inside the hydrolysis reactor reached 160°C, the timing was started. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0080] The hydrolysates obtained from the two steps were analyzed. In the first hydrolysis stage, the yield of reducing sugars from hemicellulose was 84% ​​(75% of pentose sugars, of which xylan accounted for 9%), and the cellulose retention rate in the solid residue was 90%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 83% (78% of hexose sugars, of which dextran accounted for 5%).

[0081] Example 6

[0082] Waste polystyrene (PS) and polyvinyl chloride (PVC) plastics were used as raw materials. After washing and drying, they were pulverized in a crusher. The pulverized materials were sieved to obtain 100-150 mesh particles as raw materials. 0.05 kg of PVC powder and 0.05 kg of polystyrene powder, totaling 0.1 kg, were weighed and mixed with 1.0 L of concentrated sulfuric acid in a PTFE-lined reactor at a mass-to-volume ratio of 1:10 kg / L. The reactor was heated, and the reaction conditions were set as follows: sulfonation temperature 140℃ and sulfonation time 1 h. After the reaction was completed and cooled to room temperature, the solid product was separated from the concentrated sulfuric acid using a sintered glass funnel, and the concentrated sulfuric acid was recovered for later use. The solid particles were repeatedly washed with hot water (>80℃) until the filtrate was neutral. The washed solid acid particles were placed in an oven and dried at 105℃ for 10 h before being collected for later use; this is the plastic-based solid acid catalyst.

[0083] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Corn cob particles with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and corn cob were placed in the reactor at a mass ratio of 1:2. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:10 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 140°C. After 1 hour of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial corn cob mass, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:15 (kg / L) of corn cob to water. The timing was started after the temperature inside the hydrolysis reactor reached 170°C. After 3 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0084] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 91% (the yield of pentose sugars was 82%, of which xylan accounted for 13%), and the cellulose retention rate in the solid residue was 82%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 86% (the yield of hexose sugars was 82%, of which the content of dextran was 9%).

[0085] Example 7

[0086] The preparation steps are the same as those for the plastic-based solid acid catalyst in Example 2, except that the waste plastics are 0.08 kg of polyvinyl chloride powder and 0.02 kg of polystyrene powder.

[0087] Using the aforementioned plastic-based solid acid catalyst as the catalyst, the reaction was carried out according to the method in Example 1. Poplar wood chips with a particle size of 0.1-2 mm were selected as the lignocellulose raw material. The plastic-based solid acid catalyst and poplar wood chips were placed in the reactor at a mass ratio of 1:1. Water was added to the hydrolysis reactor at a mass-volume ratio of 1:15 (kg / L). The heating device of the hydrolysis reactor was turned on, and the timing was started after the temperature inside the hydrolysis reactor reached 160°C. After 2 hours of reaction, the pretreated hydrolysate and pretreated solid residue were separated. The temperature of the heating device of the hydrolysis reactor was reset. Based on the initial mass of poplar wood chips, water was added to the hydrolysis reactor containing the pretreated solid residue at a mass-volume ratio of 1:20 (kg / L). The timing was started after the temperature inside the hydrolysis reactor reached 180°C. After 6 hours of reaction, the second hydrolysate and the second solid residue were separated.

[0088] The hydrolysates obtained from the two steps were analyzed. In the pretreatment stage, the yield of reducing sugars from hemicellulose was 85% (79% of pentose sugars, of which xylan accounted for 12%), and the cellulose retention rate in the solid residue was 93%. In the second hydrolysis stage, the yield of reducing sugars from cellulose was 83% (77% of hexose sugars, of which dextran accounted for 11%).

[0089] The above description of the embodiments is only for the purpose of helping to understand the technical solution and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method of directional catalytic depolymerization of biomass with a plastic-based solid acid catalyst, characterized in that, It comprises the following steps: (1) Catalyst hydrolysis pretreatment: the lignocellulosic raw material is mixed with the plastic-based solid acid catalyst and water as a solvent is placed in a reaction vessel, and heated reaction is carried out, and after the reaction is completed, the first solid residue and the pretreatment liquid containing xylose are separated; (2) Second-order hydrolysis: water is supplemented to the reactor of the first solid residue separated in step (1), and heating reaction is carried out again, and after the reaction is completed, the second solid residue and the second hydrolysis liquid containing glucose are separated; The preparation method of the plastic-based solid acid catalyst comprises the following steps: the pretreated waste plastic and concentrated sulfuric acid are added to a reaction vessel for sulfonation reaction, and after the reaction is completed, the solid product and the reaction liquid are separated, and the solid product is washed and dried to obtain a plastic-based solid acid catalyst containing -SO3H, -Cl, -OH and -COOH groups; the waste plastic is a mixture of polystyrene and polyethylene, polypropylene or polyvinyl chloride, and the mass ratio of polystyrene to polyethylene, polypropylene or polyvinyl chloride is 1:1-5.

2. The method of claim 1, wherein, The pretreatment step of the pretreated waste plastic is: the waste plastic is washed and dried, then crushed and sieved, the sieving mesh number is controlled between 100-150 meshes, and then washed and dried again to obtain waste plastic powder.

3. The method of claim 1, wherein, The mass volume ratio of the total mass of waste plastic to concentrated sulfuric acid is 1:5-20 kg / L, the sulfonation reaction temperature is 120℃-180℃, and the reaction time is 0.5-6 h.

4. The method of claim 1, wherein, In step (1), the mass ratio of the lignocellulosic raw material to the plastic-based solid acid catalyst is 1-4:1, and the mass volume ratio of the lignocellulosic raw material to water is 1:10-40 kg / L.

5. The method of claim 1, wherein, In step (1), the heating reaction conditions are: reaction temperature 110℃-160℃, reaction time 10-180 min.

6. The method of claim 1, wherein, In step (2), the heating reaction conditions are: reaction temperature 160℃-190℃, reaction time 1-6 h.

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