CN117884184A - Sulfonyl chloride modified lignin-based carrier loaded with phthalocyanine iron and catalytic lignin depolymerization method - Google Patents

Abstract

The invention discloses a method for loading iron phthalocyanine on a sulfonyl chloride modified lignin-based carrier and catalyzing lignin depolymerization. The sulfonyl chloride modified lignin-based carrier-supported iron phthalocyanine has a repeating unit represented by the formula (1): In the formula (1), the wavy line indicates that other repeating units shown in the formula (1) are connected, M has a structure shown in the formula (2), and R=NH ₂ or NO ₂; adopts the catalyst to carry out catalytic oxidative depolymerization on lignin, so that the condition is mild, and the selectivity of phenolic substances in the product is good.

Description

Sulfonyl chloride modified lignin-based carrier loaded with phthalocyanine iron and catalytic lignin depolymerization method

Technical Field

The invention relates to the technical field of lignin catalytic depolymerization, and in particular to a method for loading phthalocyanine iron on a sulfonyl chloride-modified lignin-based carrier and catalyzing lignin depolymerization.

Background technique

The papermaking industry will discharge smelly and toxic black liquor, the main components of which are hemicellulose and lignin that cannot be metabolized by microorganisms. At present, the main method of treating papermaking black liquor is to concentrate it and mix it with coal powder from power plants and burn it. This treatment method not only wastes resources, but also causes air pollution. Therefore, the research, development and comprehensive utilization of lignin in papermaking black liquor has become a task with important social and economic benefits.

Lignin is a three-dimensional phenolic polymer widely found in the cell walls of higher plants. It is composed of three basic aromatic structural units: syringyl (S), guaiacyl (G) and hydroxyphenyl (H) units. The three basic lignin structural monomers are mainly connected by C-C, C-O bonds, etc. Depolymerization of lignin to selectively break the C-C or C-O bonds in its structure to produce phenols or other small molecule chemicals is an important method to achieve large-scale comprehensive utilization of lignin.

Lignin can be depolymerized by pyrolysis or liquid phase catalysis. Generally speaking, the pyrolysis of lignin requires a higher reaction temperature (400-800°C) and harsh conditions. Compared with the pyrolysis method, the liquid phase catalytic degradation method has the advantages of mild reaction conditions and high product selectivity. During the liquid phase catalytic degradation of lignin, the C-C or C-O bonds break under the action of the catalyst to form aromatic or other small molecule chemicals, and the key to the liquid phase catalytic depolymerization of lignin is to prepare an effective catalyst.

Summary of the invention

The purpose of the present invention is to provide a method for loading phthalocyanine iron on a sulfonyl chloride-modified lignin-based carrier and catalyzing lignin depolymerization, so as to achieve lignin depolymerization.

The purpose of the present invention is achieved by the following technical solutions:

A sulfonyl chloride modified lignin-based carrier loaded with phthalocyanine iron, wherein the sulfonyl chloride modified lignin-based carrier loaded with phthalocyanine iron has a repeating unit as shown in formula (1):

Formula 1):

In formula (1), the wavy line represents the connection of other repeating units as shown in formula (1), M has the structure as shown in formula (2), R = NH ₂ or NO ₂ , that is, the three Rs are the same and can be selected from NH ₂ or NO ₂ ;

Formula (2):

The black bold dash in formula (2) indicates the bond to the SO ₂ group.

The sulfonyl chloride-modified lignin-based carrier-supported iron phthalocyanine is hereinafter referred to as the catalyst of formula (1). A specific structure of the catalyst of formula (1) is shown in the following structural formula.

A method for preparing the above-mentioned sulfonyl chloride-modified lignin-based carrier loaded with phthalocyanine iron comprises:

The compound represented by formula A and the compound represented by formula B are heated and reacted in a DMF solvent to obtain a sulfonyl chloride-modified lignin-based carrier loaded with phthalocyanine iron as represented by formula (1).

Preferably, the weight ratio of the compound represented by formula A to the compound represented by formula B is 1:(1-10), and the mixture is subjected to ultrasonic treatment before the heating reaction, and the heating reaction temperature is 120°C.

Specifically, the total volume (ml) of the DMF solvent may be 5-50 times the total weight (g) of the compound represented by Formula A and the compound represented by Formula B.

A method for catalytic lignin depolymerization, comprising:

Lignin and the sulfonyl chloride-modified lignin-based carrier loaded with phthalocyanine iron as shown in formula (1) are placed in a mixed solvent of water and acetonitrile, the pH value of the solution is less than 5 and greater than 1, hydrogen peroxide is added, and heating and stirring are performed to achieve lignin depolymerization.

The volume ratio of water to acetonitrile can be 6:1-1:1, and the total volume (ml) of the mixed solvent can be 50-250 times the weight (g) of lignin.

Preferably, based on the weight of lignin, the weight ratio of the sulfonyl chloride modified lignin-based carrier loaded with iron phthalocyanine is 0.5 wt%-6 wt%.

Preferably, based on the weight of lignin, the weight ratio of the sulfonyl chloride modified lignin-based carrier loaded with iron phthalocyanine is 3.5 wt %.

Preferably, the heating temperature is 120-150° C. and the reaction time is 40-200 min.

Preferably, the heating temperature is 135° C., the reaction time is 120 min, and the pH value of the solution is adjusted to 3 with sulfuric acid.

Preferably, the concentration of the hydrogen peroxide solution is 2.5×10 ^-2 -20×10 ^-2 mol/L.

Preferably, the concentration of the hydrogen peroxide solution is 15×10 ^-2 mol/L.

Compared with the prior art, the beneficial effects of the present invention include at least:

The invention prepares a novel sulfonyl chloride modified lignin-based carrier loaded with phthalocyanine iron, and adopts the catalyst to carry out catalytic oxidation depolymerization of lignin, with mild conditions and good selectivity of phenolic compounds in the depolymerization product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a FT-IR spectrum of the compound of formula B and the catalyst of formula (1) according to an embodiment of the present invention.

FIG. 2 is a BET analysis diagram of compound A and the catalyst of formula (1) according to an embodiment of the present invention.

FIG. 3 is an analysis chart of the effect of catalyst content on liquid product yield and phenol selectivity in an embodiment of the present invention.

FIG. 4 is an analysis chart of the effect of H ₂ O ₂ concentration on the yield of liquid phase products and the selectivity of phenols in an embodiment of the present invention.

FIG. 5 is an analysis chart of the effect of reaction time on the yield of liquid phase products and the selectivity of phenols in an embodiment of the present invention.

FIG. 6 is a picture of the ethyl acetate soluble portion in Examples 5-9 of the present invention.

FIG. 7 is a GC-MS spectrum of the ethyl acetate extraction product in Examples 5-9 of the present invention.

FIG8 is an FT-IR spectrum of the ethyl acetate extraction product in Examples 5-9 of the present invention.

FIG. 9 is a SEM image of the solid residue obtained at different reaction times in Example 18 of the present invention.

Detailed ways

Example embodiments will now be described more fully. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete and to fully convey the concept of example embodiments to those skilled in the art.

In the examples, the main reagents used include potassium hydroxide (KOH, purity ≥98%), sodium hydroxide (NaOH, purity ≥97%), sulfuric acid (H ₂ SO ₄ , concentration 98%), ferric chloride hexahydrate (FeCl ₃ ·6H ₂ O), ethanol (C ₂ H ₅ OH, 99.9%), hydrogen peroxide (H ₂ O ₂ ), thionyl chloride (SOCl ₂ ), 4-nitrophthalic acid (C ₈ H ₅ NO ₆ ), urea (CO(NH ₂ ) ₂ ), sodium sulfide (NaS ₂ ·9H ₂ O) and N,N-dimethylformamide (C ₃ H ₇ NO), all of which are commercially available.

Example 1: Preparation of Compound A

The lignin in the embodiment (as shown in Formula A1) is recovered from papermaking black liquor, and then a lignin-based carbon sulfonyl chloride derivative (compound of Formula A) is synthesized through three steps of carbonization, sulfonation and chlorination.

Specifically, first, carbonize lignin in a tube furnace under _N2 protection, put lignin and KOH in a nickel pan in proportion (weight ratio of 1: (0.5-3), 1: 2 in this embodiment), and then place it in the center of the tube furnace, heat the tube furnace to 550 ° C, the heating rate is 15 ° C / min, and finally keep it for 90 minutes. After the reaction is completed, the obtained black sample is washed with hot water and filtered, and then dried at 105 ° C for 12 hours to obtain carbonized lignin. Then, the carbonized lignin is sulfonated in a three-necked round-bottom flask under _N2 protection. Carbonized _lignin and _H2SO4 are mixed in a round-bottom flask in a weight ratio of 1: (5-13), reacted at 150 ° C for 6 hours, and finally a black sample (named sulfonated lignin, as shown in formula A2) is obtained, washed and filtered with water, and finally dried at 105 ° C for 12 hours. Finally, the synthesis of the compound represented by formula A can refer to the known method for preparing sulfonyl chloride from sulfonic acid compounds. Specifically, the compound represented by A2 is added to an excess of SOCl ₂ solution and reacted at 90° C. for 24 hours. After the reaction is completed, the residual SOCl ₂ is distilled off, and the solid product (as represented by formula A) is washed and dried for later use.

Example 2: Structure of the compound of formula B

The structure of the compound of formula B is shown in the above structure, wherein R=NH ₂ or NO ₂ . The compound can be prepared by a known method, and its preparation method will not be described in detail.

Example 3: Preparation of the catalyst of formula (1)

The compound of formula A and the compound of formula B prepared above (wherein, in this embodiment and the following embodiments, R is NH ₂ , and the weight ratio is 1:1.2) are added to DMF solvent, the total volume (ml) of the solvent is 5 times the total weight (g) of the compound represented by formula A and the compound represented by formula B, a small amount of water (for example, the volume of water is 5% of the volume of DMF) can be added to the solvent, ultrasonically treated for 2 hours, and then the mixture is stirred at 120°C for 72 hours, and finally the reaction mixture is filtered to obtain a solid, the solid is washed with water and acetone, and dried at 65°C to obtain a black blue powder catalyst (catalyst of formula (1), R is NH ₂ ).

Example 4-18: Catalytic oxidative depolymerization of lignin

First, an appropriate amount of the catalyst of formula (1) (the weight ratio of the catalyst to lignin is 0wt% to 4.5wt%) is dispersed in a mixed solvent of water and acetonitrile (the volume ratio of the two is 4:1), and the total volume (ml) of the mixed solvent is 100 times the weight (g) of lignin; secondly, lignin (1g) is added to the above mixture, and the pH of the mixture is adjusted to 3.0 with sulfuric acid. Subsequently, the mixture is vibrated for 20-30min to fully disperse the catalyst of formula (1) and lignin; finally, _H2O2 (based on the total volume of the mixed solvent of water and acetonitrile, the concentration of _H2O2 is 0mol/L to 20× _10-2 mol/L) is added to the reaction mixture while the mixture is transferred to a _150ml reactor, and the mixture is stirred at ¹³⁵ °C for 40-200min. After the reaction is completed, the solid residue and the liquid product are obtained by centrifugation, and the liquid product is extracted with ethyl acetate to obtain ethyl acetate soluble matter for analysis.

For specific reaction conditions in Examples 4-18, see Table 1.

Table 1

Result analysis:

The chemical functional group types of the catalysts were analyzed by Nicolet IS10 Fourier transform infrared spectroscopy (FTIR); the BET surface area was tested using _N2 adsorption/desorption isotherms (Quantachrome autosorb IQ-C analyzer). The surface structure of the catalysts was analyzed by Hitachi s-3400 scanning electron microscope (SEM) (Hitachi, Japan).

The depolymerization product was analyzed using an Agilent 6890A/5973N instrument equipped with a HP-5MS (30m×0.25mm×0.25μm) column. The analysis conditions were as follows: 2μL of sample was injected into the system at 40°C and maintained at 40°C for 2 minutes, then heated to 150°C at a rate of 5°C/min and maintained for 2 minutes, then heated to 280°C at a rate of 8°C/min and maintained for 5 minutes. The elemental composition of the product was analyzed using an elemental analyzer (EA).

The surface structure of the solid residue was analyzed by Hitachis-3400 scanning electron microscope.

The liquid product yield is calculated as follows:

Liquid phase product (wt%) = W _{liquid phase product} / W _lignin × 100%.

Wherein _Wlignin and _{Wliquid product} represent the weight of lignin and the weight of liquid product, respectively.

The selectivity of phenolic compounds was expressed as the ratio of the peak area of the corresponding product to the total area of the liquid phase products.

FIG1 is a FT-IR spectrum of the compound of formula B and the catalyst of formula (1) in the embodiment of the present invention. Referring to FIG1 , line a represents the compound of formula B, and line b represents the catalyst of formula (1). The FT-IR spectrum of FIG1 shows that the characteristic peaks of iron phthalocyanine appear at 1320 cm ^-1 , 1120 cm ^-1 , and 740 cm ^-1 , which is attributed to the vibration of the phthalocyanine ring. The spectrum of the catalyst of formula (1) clearly shows similar characteristic bands, indicating that iron phthalocyanine is bonded to the compound of formula A. A new characteristic peak of SN stretching vibration appears near 900 cm ^-1 , indicating that iron phthalocyanine is successfully introduced into the compound of formula A through chemical reaction.

2 , line a represents the compound of formula A, line b represents the catalyst of formula (1), and Table 2 shows the porous structure characterization results of compound A and catalyst of formula (1).

Table 2

sample S _BET (m ² /g) S _Mic (m ² /g) V _total (cm ³ /g) V _Mic (cm ³ /g) Compound of formula A 643.67 540.79 0.337 0.210 Catalyst of formula (1) 638.98 603.57 0.291 0.246

Referring to FIG. 2 , when P/P0 is lower than 0.2, a steep slope can be seen, which can confirm that the two N2 adsorption-desorption isotherms conform to the type I adsorption isotherm and the H4 type hysteresis loop, which can also prove that there are a large number of micropores in the sample. The detailed specific surface area and pore structure parameters of the compound of formula A and the catalyst of formula (1) are shown in Table 2. The catalyst sample of formula (1) exhibits a lower specific surface area and pore volume. When iron phthalocyanine is loaded on the compound of formula A, the BET specific surface area decreases from 643.67m ² /g to 638.98m ² /g, and at the same time, the pore volume decreases from 0.337cm ³ /g to 0.291cm ³ /g. The decrease in BET surface area and pore volume may be due to the blockage of some pores of the carrier by iron phthalocyanine.

The depolymerization efficiency of lignin and the composition and properties of the liquid phase product are affected by the reaction conditions, such as the content of the catalyst, the reaction time, etc. Examples 4-18 investigated the effect of specific reaction conditions on the depolymerization efficiency of lignin.

FIG3 is an analysis diagram of the effect of catalyst content on the yield of liquid products and the selectivity of phenols in the embodiments of the present invention. Most reactions are affected by the active sites and basic properties of the catalyst. Based on this, referring to Examples 4-9, the present invention uses six different catalyst concentrations: 0wt%, 0.5wt%, 1.5wt%, 2.5wt%, 3.5wt%, and 4.5wt%. As can be seen from FIG3, with the increase of catalyst content, the yield of liquid products and the selectivity of phenols are both improved compared with the case of no catalyst degradation. When 3.5wt% of catalyst is used, the maximum yield of liquid products is 38.94%; at the same time, the selectivity of phenols also reaches the highest value of 32.58%. When the catalyst content is increased to 4.5wt%, the yield of liquid products and the selectivity of phenols are both reduced.

These results indicate that the appropriate catalyst dosage has a certain effect on the yield of liquid products and the selectivity to phenols. Once the catalyst dosage exceeds the optimal value, the yield of liquid products and the selectivity to phenols may decrease.

FIG4 is an analysis chart of the effect of H ₂ O ₂ concentration on the yield of liquid products and the selectivity of phenols in the examples of the present invention. Referring to Examples 8 and 10-14, six different levels of H ₂ O ₂ concentration (0 mol/L, 2.5×10 ^-2 mol/L, 5×10 ^-2 mol/L, 10×10 ^-2 mol/L, 15×10 ^-2 mol/L, 20×10 ^-2 mol/L) were used, 3.5 wt% catalyst was used, and the reaction was carried out at 135°C and pH 3.0 for 120 min. As the H ₂ O ₂ concentration increased from 0 mol/L to 20×10 ^-2 mol/L, similar trends were observed in the yield of liquid products and the selectivity of phenols. As the concentration of hydrogen peroxide increases from 0 mol/L to 15×10 ^-2 mol/L, the yield of liquid products and the selectivity of phenolic compounds increase with the increase of hydrogen peroxide concentration. When the concentration of H ₂ O ₂ is 15×10 ^-2 mol/L, the yield is as high as 38.94%, and the selectivity of phenolic compounds is as high as 32.58%. When the concentration of H ₂ O ₂ is further increased, the yield of liquid products does not change significantly, but the selectivity of phenolic compounds decreases significantly.

Fig. 5 is an analysis diagram of the reaction time to the yield of liquid products and the selectivity of phenols in the embodiment of the present invention, with reference to Example 8 and Example 15-18, as can be seen from Fig. 5, as the reaction time increases to 2h, the yield of liquid products and the selectivity of phenolic compounds gradually increase, and when the reaction time is 2h, both values reach maximum values; as the reaction time is further extended to 160min and 200min, the yield of liquid products and the selectivity of phenolic compounds begin to decline. When the reaction time is 200min, the yield of liquid products and the selectivity of phenolic compounds all present minimum values, which shows that when the reaction time exceeds 2h, it is not conducive to the reaction.

The reaction process and properties of the liquid products at 5 different catalyst concentrations (0.5wt%, 1.5wt%, 2.5wt%, 3.5wt%, 4.5wt%) in Examples 5-9 were analyzed. Specifically, the obtained liquid product was extracted with ethyl acetate, and the ethyl acetate solubles are shown in Figure 6. The product composition was analyzed by GC-MS, and the results are shown in Figure 7.

All samples in Figure 6 (0.5wt%, 1.5wt%, 2.5wt%, 3.5wt%, 4.5wt%, corresponding to samples a to e) showed different colors. As the catalyst content increased, the color changed from light yellow to dark brown. As can be seen from Figure 7, the depolymerization products obtained when using different catalyst concentrations are significantly different. The detected products mainly include phenolic compounds, esters and aldehydes, etc. The detailed information of the depolymerization products is summarized in Table 3.

table 3

As shown in Table 3, chemical substances such as ethyl propionate, butyl acetate, acetosyringone, phenol, and 2,6-bis(1,1-dimethylethyl)-naphthalene account for a large proportion of the total integrated area. 2,4-di-tert-butylphenol was observed to account for a large proportion of the products obtained when different catalyst concentrations were selected. When the catalyst concentration was 0.5wt%, the main compound in the product was 2,3-dihydro-benzofuran, accounting for 13.72% of the total integrated area; followed by ethyl propionate, accounting for 5.54% of the total integrated area; 2,4-di-tert-butylphenol, accounting for 3.01% of the total integrated area. When the catalyst concentration was 1.5wt%, the compound 2,3-dihydro-benzofuran accounted for most of the total integrated area, accounting for 48.16%; followed by ethyl propionate and 2,4-di-tert-butylphenol, accounting for 17.42% and 10.12% of the total integrated area, respectively. The compounds 3-hydroxy-4-methoxybenzaldehyde and eicosane accounted for 5.38% and 3.09% of the total integrated area, respectively. When the catalyst concentration was 2.5wt%, 3.5wt% and 4.5wt%, the compound ethyl propionate accounted for the largest total integrated area, 65.18%, 51.59% and 59.06%, respectively; followed by 2,4-di-tert-butylphenol, accounting for 15.73%, 14.84% and 17.08% of the total integrated area, respectively.

It is worth noting that as the catalyst concentration increases to 3.5wt%, the total proportion of phenolic compounds reaches the maximum, and the types of phenolic compounds also change. The phenolic compounds obtained include phenol, 2-methoxyphenol, 2,4-di-tert-butylphenol, 2,3-dimethoxyphenol, 3,4-dimethoxyphenol, and 2,6-dimethoxyphenol, which account for the largest proportion of the total integral area, that is, 14.84%; 2,6-dimethoxyphenol accounts for 10.78% of the total integral area. The compounds 2,3-dimethoxyphenol and 3,4-dimethoxyphenol account for relatively less total integral area and only appear at 3.5wt% catalyst. For 2,4-di-tert-butylphenol, as the catalyst content increases from 0.5wt% to 4.5%, its proportion increases from 3.01% to 17.08%, indicating that the catalyst promotes the production of 2,4-di-tert-butylphenol. Relative to phenol, as the catalyst dosage increases from 0.5wt% to 4.5%, its proportion first increases from 0.16% to 4.22%, and when the catalyst dosage is 4.5wt%, the phenol proportion decreases to 3.7%; when the catalyst dosage is 0.5wt% and 1.5wt%, no 2,6-dimethoxyphenol is observed, and when the catalyst dosage increases from 2.5wt% and 3.5wt%, the proportion of 2,6-dimethoxyphenol increases, reaching 2.15% and 10.78% respectively, and when the catalyst concentration further increases to 4.5wt%, the proportion of 2,6-dimethoxyphenol decreases to 0.9%. When the catalyst dosage is 1.5wt%, 2.5wt% and 3.5wt%, the proportion of 2-methoxyphenol is 0.61%, 0.72% and 1.56% respectively, and when the catalyst is further increased to 4.5%, its proportion decreases to 0.61%.

In order to further confirm the chemical functional group characteristics of the degradation products of each sample in Figure 6, FT-IR analysis was performed, and the results are shown in Figure 8.

As shown in Figure 8, the products have similar chemical functional groups, and the positions of the vibration peaks are basically the same. This result shows that the main components of the depolymerization products have similar structures. The wide band at 3480 cm ^-1 is attributed to the stretching vibration peaks of OH, =CH and NH in aromatic or aliphatic groups, indicating the presence of phenols or benzene rings in the product; the peaks at 2938 and 2841 cm ^-1 are attributed to the asymmetric stretching vibrations of methyl and methylene CH, indicating the presence of saturated aliphatic hydrocarbons in the product; the small and wide band near 1702 cm ^-1 is attributed to the stretching vibration of C=O in ketone or carboxylic acid derivatives; the peaks near 1590 and 1505 cm ^-1 are attributed to the vibration of the C=C bond in the aromatic skeleton. This result shows that the aromatic skeleton structure of lignin is well preserved in the product. The peaks at 1273 and 1120 cm ^-1 are attributed to the Ar-O bond of methoxyphenol.

The elemental compositions of the products of Examples 5-9 were analyzed and the results are shown in Table 4.

Table 4

The results of elemental analysis show that compared with lignin, the carbon content in the product has increased, and the carbon content is the highest when the catalyst dosage is 3.5wt%; the hydrogen content is slightly higher than that of lignin, and the oxygen content is lower than that of lignin. The lowest oxygen content is 21.8% in the product with a catalyst dosage of 3.5wt%. At the same time, the calorific value (HHV) of the product is enhanced. The HHV of lignin is 20.5MJ/kg, and the HHV value of the product increases to 23.3-30.2MJ/kg, with the highest HHV being 30.2MJ/kg.

For Example 18, SEM analysis was used to study the changes in the microstructure of lignin at different depolymerization times (40 min, 80 min, 120 min, and 150 min), and the results are shown in Figure 9. Figure 9 a is lignin, 40 min corresponds to Figure 9 b, 80 min corresponds to Figure 9 c, 120 min corresponds to Figure 9 e, and 150 min corresponds to Figure 9 f.

As can be seen from Figure 9a, lignin has a relatively smooth and dense surface structure. When the reaction time is extended to 40min (Figure 9b), the smooth surface is slightly damaged, some shallow pits are observed, and a small amount of scum is deposited on the surface of lignin, indicating that the depolymerization of lignin starts from the surface; further reacting to 80min (Figure 9c), the surface damage is aggravated, and some deeper pits appear. When the figure is enlarged and observed (Figure 9d), more fragments can be found attached to the surface or in the pits, indicating that the main reaction at this stage is the depolymerization of lignin. When the reaction time is further extended to 120min (Figure 9e), slight agglomeration can be observed, indicating that with the increase of reaction time, the coupling and polycondensation reactions of the intermediate products begin to become obvious. When the reaction time is further increased to 150min (Figure 9f), agglomeration can be observed, indicating that a longer time promotes the coupling and polycondensation reactions of the intermediate products.

Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the invention without departing from the principles and purpose of the present invention. All such changes should fall within the scope of protection of the claims of the present invention.

Claims (10)

1. A sulfonyl chloride modified lignin-based carrier-supported iron phthalocyanine, characterized in that the sulfonyl chloride modified lignin-based carrier-supported iron phthalocyanine has a repeating unit represented by formula (1):

Formula (1):

In formula (1), the wavy line indicates that other repeating units represented by formula (1) are linked, M has a structure represented by formula (2), r=nh ₂ or NO ₂;

formula (2):

2. A method for preparing the sulfonyl chloride modified lignin-based carrier-supported iron phthalocyanine of claim 1 comprising:

And (3) heating the compound shown in the formula A and the compound shown in the formula B in a DMF solvent for reaction to obtain the sulfonyl chloride modified lignin-based carrier loaded iron phthalocyanine shown in the formula (1).

3. The method for preparing sulfonyl chloride modified lignin-based carrier supported iron phthalocyanine according to claim 2, wherein the weight ratio of the compound represented by formula a to the compound represented by formula B is 1: (1-10), prior to the heating reaction, subjecting the mixture to ultrasonic treatment, the temperature of the heating reaction being 120 ℃.

4. A method of catalyzing depolymerization of lignin, comprising:

placing lignin and sulfonyl chloride modified lignin-based carrier loaded iron phthalocyanine shown in a formula (1) in claim 1 into a mixed solvent of water and acetonitrile, adding hydrogen peroxide to the solution until the pH value of the solution is less than 5 and greater than 1, heating and stirring to realize lignin oxidative depolymerization.

5. The method for catalyzing depolymerization of lignin according to claim 4, wherein the sulfonyl chloride modified lignin-based carrier supports iron phthalocyanine in a weight ratio of 0.5wt% to 6wt% based on the weight of lignin.

6. The method for catalyzing depolymerization of lignin according to claim 5, wherein the sulfonyl chloride modified lignin-based carrier supports iron phthalocyanine in a weight ratio of 3.5wt% based on the weight of lignin.

7. The method for depolymerizing lignin by catalysis according to claim 4, wherein the heating temperature is 120-150 ℃ and the reaction time is 40-200min.

8. The method for depolymerizing lignin by catalysis according to claim 7, wherein the heating temperature is 135 ℃, the reaction time is 120min, and the pH value of the solution is adjusted to 3 by sulfuric acid.

9. The method for depolymerizing lignin by catalysis according to claim 4, wherein the concentration of hydrogen peroxide is 2.5X10 ^-2-20×10^-2 mol/L.

10. The method for catalyzing depolymerization of lignin according to claim 9, wherein the concentration of hydrogen peroxide is 15 x 10 ^-2 mol/L.