CN115672332A - Papermaking black liquor lignin conversion catalyst and preparation method and application thereof - Google Patents

Abstract

The invention discloses a lignin conversion catalyst for papermaking black liquor, a preparation method and application thereof, and relates to the technical field of lignin conversion. The preparation method comprises the following steps: (1) Carrying out thermal reaction on an acid solution and a carrier, and washing until the pH value of a washing liquid is between 6 and 7 to obtain an acidified carrier; (2) Dipping the metal precursor on the surface of the acidified carrier to obtain a carrier loaded with metal; (3) Drying and roasting the carrier loaded with the metal to obtain roasted active carbon; (4) And (3) carrying out reduction, vulcanization or phosphorization treatment on the roasted activated carbon to obtain the lignin conversion catalyst for the papermaking black liquor. In the preparation process, alkali-resistant activated carbon is used as a carrier, so that the activated carbon has high alkali resistance and good stability under a strong alkaline condition, surface acid modification is carried out on the activated carbon, and a certain amount of acidic groups are introduced to the surface of the activated carbon, so that the activated carbon has good deoxidation activity.

Description

A papermaking black liquor lignin conversion catalyst and its preparation method and application

technical field

The invention relates to the technical field of lignin conversion, in particular to a papermaking black liquor lignin conversion catalyst and its preparation method and application.

Background technique

The paper industry is one of the most polluting industries in my country. According to statistics, the discharge of paper products and pulping and papermaking wastewater at and above the county level in my country is second only to the annual discharge of chemical raw materials and chemical products manufacturing. The pollution produced by papermaking black liquor accounts for about 90% of the total pollution. Therefore, the treatment of papermaking black liquor is one of the difficult problems that have been devoted to solving both at home and abroad. In the traditional alkaline pulping process, the lignin dissolved into the pulping black liquor accounts for about 30% of the mass of the wood raw material. However, due to the complex structure of lignin in papermaking black liquor, it is difficult to process it. At the same time, the strong alkalinity of papermaking black liquor makes the processing method of black liquor lignin very demanding. Currently, only 5% of lignin is used as low-grade fuel in the market. , Concrete admixture (lignin sulfonate) and other low-value commodities are consumed, and more than 90% of lignin cannot be utilized, but is directly discharged as papermaking pulping waste. Therefore, it is of great practical significance to recycle and convert lignin from papermaking black liquor into high-value chemicals.

The current preparation method of lignin catalytic conversion catalyst uses noble metals and acidic carriers such as alumina, molecular sieves, etc. to catalyze the conversion of lignin. For example, Chinese patent application 201910845937.1 discloses a black liquor lignin hydrogenolysis catalyst and its preparation method and application. The catalyst comprises HZSM-5 molecular sieve, titanium dioxide and noble metal iridium components, the loading of iridium on HZSM-5 is 1wt%-30wt%, the loading of titanium dioxide on HZSM-5 is 10wt%-50wt%, the catalyst micro The pore diameter is 0.55-0.60nm. This kind of catalyst is used to catalyze the conversion of papermaking black liquor lignin. The treatment method includes firstly reacting papermaking black liquor with inorganic acid to neutralize and remove the alkali in papermaking black liquor, and then reacting the acid-insoluble lignosulfonate solid with Liquid separation, and then catalytic hydrogenolysis or catalytic alcoholysis of the obtained lignosulfonate to obtain lignin-based bio-oil, or continue catalytic hydrogenation of lignin-based bio-oil to prepare high value-added chemicals. In this process, the metal sites provide the ability to activate hydrogen to depolymerize lignin macromolecules, and the acidic carrier provides acid sites to deoxidize the obtained small lignin molecules. Although this method can effectively obtain high value-added chemicals such as phenol, there are still many shortcomings, which can be summarized as the following points: First, since the pH value of papermaking black liquor is about 13, inorganic acid acidification treatment of papermaking black liquor It causes a serious waste of inorganic acid and inorganic alkali resources in papermaking black liquor; secondly, due to the complexity of the molecular structure of lignosulfonate, the composition of the bio-oil obtained after catalytic depolymerization of lignosulfonate is complex and the composition is mostly Phenolic compounds make it difficult to separate the target product, and it is difficult to apply in the large-scale chemical industry; thirdly, due to the strong alkalinity and high sulfur content of the papermaking black liquor, the strong alkalinity will seriously damage the skeleton structure of the acidic carrier, resulting in catalyst deactivation. High sulfur content will quickly poison noble metal catalysts, making such catalysts unsuitable for papermaking black liquor systems; in addition, noble metal catalysts are expensive and difficult to apply industrially.

Therefore, there is an urgent need for a paper-making black liquor lignin conversion catalyst that is economical, sulfur-resistant, alkali-resistant and high in catalytic activity and a preparation method thereof.

Contents of the invention

Based on the shortcomings and deficiencies in the prior art, the present invention provides a papermaking black liquor lignin conversion catalyst and its preparation method and application. Compared with the current papermaking black liquor lignin conversion catalyst, the catalyst prepared by the present invention can It has sulfur resistance, alkali resistance and high catalytic activity in the lignin conversion process of papermaking black liquor, and solves the problems of poor stability and high cost of existing catalysts under alkaline conditions.

The present invention solves the above-mentioned technical problems and realizes through the following technical solutions:

On the one hand, the invention provides a kind of preparation method of papermaking black liquor lignin conversion catalyst, comprises the following steps:

(1) Washing the acid solution and the carrier after thermal reaction until the pH value of the washing solution is between 6-7 to obtain the acidified carrier;

(2) impregnating the metal precursor on the surface of the acidified carrier prepared in step (1) to obtain a metal-loaded carrier;

(3) Drying and calcining the metal-loaded carrier obtained in step (2).

The acid solution in step (1) is 1-80wt% hydrochloric acid, phosphoric acid, sulfuric acid or nitric acid; preferably, the acid solution is 2.5wt% nitric acid or sulfuric acid.

The carrier described in the above step (1) is woody activated carbon, fruit shell activated carbon, coconut shell activated carbon, coal-based activated carbon or petroleum coke-based activated carbon, and the specific surface area of the described carrier is 700-2000m ² /g, and the described carrier The mass ratio of the carrier to the acid solution is 1:2-10; preferably, the carrier is coconut shell activated carbon, and the mass ratio of the carrier to the acid solution is 1:10.

The temperature of the thermal reaction in the above step (1) is 40-80° C., and the time is 2-10 h; preferably, the temperature of the thermal reaction is 50° C., and the time is 3 h.

The metal loaded on the surface of the metal-loaded carrier described in the above step (2) is selected from one of vanadium, molybdenum, bismuth, nickel, iron, antimony, tungsten, copper, iron, niobium, chromium, magnesium, zinc and aluminum one or two; preferably nickel.

The total atomic load of the active metal loaded on the surface of the metal-loaded carrier described in the above step (2) is 5-80%.

The drying and roasting conditions described in the above step (3) are: after drying at 80-120°C for 2-12h, then roasting at 300-550°C for 2-8h; preferably, the drying and roasting conditions are: 120°C After drying for 4 hours, it was fired at 400°C for 4 hours.

The preparation method of the above-mentioned papermaking black liquor lignin conversion catalyst also includes step (4), and the carrier after roasting obtained in step (3) is reduced, vulcanized or phosphated:

The reduction treatment conditions are as follows: the reduction temperature is 150-500°C, the reducing atmosphere is _H2 or _H2 /Ar mixed gas, the reduction time is 1-6h, and the reduced catalyst is obtained after treatment;

The vulcanization treatment conditions are as follows: the vulcanization temperature is 250-500° C., the vulcanization agent is one of thiourea, H ₂ S, DMDS and CS ₂ , the vulcanization time is 1-6 hours, and the vulcanized catalyst is obtained after treatment;

The phosphating treatment conditions are: the phosphating temperature is 250-500°C, the phosphating agent is one of triphenylphosphine, phosphoric acid, ammonium dihydrogen phosphate, diamine hydrogen phosphate and urea phosphate, and the phosphating time is 1 -6h, the phosphated catalyst was obtained after treatment.

On the other hand, the present invention also provides the catalyst prepared by the above preparation method, the catalyst has a surface area of 700-1000m ² /g, a pore volume of 0.3-0.5cm ³ /g, an average pore diameter of 0.5-2nm, and a total surface area of The acid content is 1-8mmol/g.

In another aspect, the present invention also provides the application of the catalyst prepared by the above preparation method in the catalytic conversion of lignin from papermaking black liquor.

Compared with prior art, the beneficial effect of the present invention is:

(1) In the implementation process, the alkali-resistant activated carbon is selected as the carrier, so that the catalyst has good stability under strong alkaline conditions, and the catalytic treatment is carried out in a strong alkaline solution, and the skeleton structure of the carrier is not destroyed;

(2) During the implementation process, the activated carbon is heat-treated with inorganic acid, so that the surface of the activated carbon introduces hydroxyl, carboxyl and lactone groups, which provides acidic active sites for catalytic hydrodeoxygenation, thereby effectively improving the hydrodeoxygenation activity of the catalyst;

(3) The catalyst of the present invention is supported by non-noble metals, so that it can maintain excellent catalytic activity in the sulfur-containing system;

(4) In the present invention, the carrier impregnated with the metal precursor is dried, calcined, and then reduced, vulcanized or phosphated, and finally the catalyst has good hydrogenation activity while obtaining an alkali-resistant and sulfur-resistant catalyst.

The catalysts for alcoholysis and hydrodeoxygenation of papermaking black liquor lignin in existing reports use lignosulfonate obtained after acidification of papermaking black liquor as raw materials, and use noble metal catalysts and acidic carriers such as alumina and molecular sieves to treat lignin. Carry out catalytic conversion, use metal sites to achieve the purpose of depolymerization of lignin compounds, and use acid sites to achieve the purpose of hydrodeoxygenation of lignin compounds. However, the acidification treatment of papermaking black liquor caused a serious waste of inorganic acid and inorganic alkali resources; the researchers used lignosulfonate obtained from acidification treatment of papermaking black liquor as raw materials because precious metals are easily absorbed in papermaking black liquor with high sulfur content. Inactivation, and the acid carrier has extremely poor stability in black liquor with strong alkalinity, and cannot achieve satisfactory catalytic activity. However, using the preparation method of the papermaking black liquor lignin conversion catalyst provided by the present invention, by using activated carbon with high alkali resistance as a carrier, acid sites are introduced to the surface of activated carbon through acidification treatment, and non-precious metals are loaded for reduction, sulfuration or phosphorus Chemical treatment, and then prepare a catalyst with high sulfur resistance, high alkali resistance and high catalytic activity, thus greatly improving the stability and catalytic activity of the catalyst in the process of alcoholysis hydrodeoxygenation treatment with papermaking black liquor as raw material . At the same time, the catalyst prepared by the method provided by the invention has a wide range of applications, and can be applied to alkaline and non-alkaline systems such as papermaking black liquor, sawdust, lignosulfonate, etc. range of industrial applications.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

Fig. 1 is a flowchart of a method for preparing a catalyst for alcoholysis and hydrodeoxygenation of papermaking black liquor lignin in an embodiment of the present invention.

Fig. 2 is the X-ray diffraction pattern of sample C1 in Example 1 before and after the reaction.

Fig. 3 is the BET diagram of sample C1 in Example 1 before and after the reaction.

4 is a transmission electron microscope TEM image of sample C1 in Example 1 before and after reaction.

FIG. 5 is a Py-IR diagram of sample C1 in Example 1 before and after the reaction.

6 is a Py-IR diagram of sample E1 in Comparative Example 1 and C1 in Example 1.

Detailed ways

The preparation method of the papermaking black liquor lignin conversion catalyst of the present application is further described in detail below. The protection scope of the present application is not limited, and the protection scope is defined by the claims. Certain disclosed specific details provide a thorough understanding of the various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, and with other materials and the like.

Unless the context requires otherwise, in the specification and claims, the terms "comprising" and "comprising" should be interpreted as an open and including meaning, that is, "including, but not limited to".

The "embodiment", "an embodiment", "another embodiment" or "certain embodiments" mentioned in the specification refer to the described specifically related features and structures related to the embodiment or characteristics are included in at least one embodiment. Thus, "an embodiment," "an embodiment," "another embodiment," or "certain embodiments" are not necessarily all referring to the same embodiments. Furthermore, the particular features, structures or characteristics may be combined in any manner in one or more embodiments. Each feature disclosed in the specification can be replaced by any alternative feature that can serve the same, equivalent or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equivalent or similar features.

Embodiments of the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and therefore are only examples, rather than limiting the protection scope of the present invention.

The manufacturers of the reagents or medicines used in the following examples are as follows:

The following will be described in conjunction with specific embodiments.

Example 1

Take by weighing 2.5g of nitric acid and place it in a beaker, add 97.5g of deionized water, stir evenly, and obtain the nitric acid solution for use; take by weighing 20g of coconut shell activated carbon and place it in a 500ml round bottom flask, then add the prepared nitric acid solution, at 50 Stir in a constant temperature water bath at 400r/min for 3 hours; use a large amount of deionized water to wash the activated carbon, filter it several times until the pH value of the filtrate is between 6-7, and then dry it in an oven at 120°C for 8 hours to obtain acidified activated carbon, which is denoted as S- 1.

Measure the water absorption of carrier S-1 to 0.95ml/g, weigh 10g of S-1 prepared in Example 1, 7.0079g of nickel nitrate hexahydrate and 9.5g of deionized water; add nickel nitrate hexahydrate and deionized water to 20ml Place the metal precursor in a glass beaker and stir it on a magnetic stirrer for 1 min; impregnate the metal precursor on the surface of S-1 by equal volume impregnation method, place it at room temperature for 12 hours to dry, and then dry it in an oven at 120 °C 2h, and then calcined in a muffle furnace at 400°C for 4h to obtain the calcined activated carbon, denoted as B1.

Take 5ml of B1 and place it in a fixed bed reactor, and carry out reduction treatment in a hydrogen atmosphere, first pass hydrogen gas (30ml/min) until the reaction pressure is 1MPa, then start to increase the temperature (2°C/min) to 400°C, and stabilize for 4h , after cooling down to room temperature, the catalyst was taken out to obtain the reduced catalyst C1.

Example 2

Weigh 5g of sulfuric acid and place it in a beaker, add 97.5g of deionized water, stir evenly to obtain a sulfuric acid solution for use; weigh 20g of fruit shell activated carbon and place it in a 500ml round-bottomed flask, then add the prepared sulfuric acid solution, at 40°C Stir in a constant temperature water bath at 400r/min for 10h, then use a large amount of deionized water to wash the activated carbon, filter it several times until the pH value of the filtrate is between 6-7, and then dry it in an oven at 120°C for 8h to obtain acidified activated carbon, which is denoted as S- 2.

Measure the water absorption of carrier S-2 to 0.92ml/g; weigh 10g of S-2 prepared in Example 1, 4.713g of nickel nitrate hexahydrate, 1.808g of ammonium paramolybdate and 9.5g of deionized water, and add it to a 20ml glass beaker , placed on a magnetic stirrer and stirred for 1 min, the metal precursor was obtained; the metal precursor was impregnated on the surface of S-1 by equal-volume impregnation method, placed at room temperature for 12 h to dry, and then dried in an oven at 80 °C for 12 h. Then it was calcined at 450°C for 8 hours in a muffle furnace to obtain the calcined activated carbon, which was denoted as B2.

Measure 5ml of B2 and place it in a fixed-bed reactor, carry out sulfuration treatment in a 10wt% _H2S / _H2 atmosphere, first feed 10wt% _H2S / _H2 gas (30ml/min), until the reaction pressure is 3MPa, then start to raise the temperature (2°C/min) to 450°C, keep it stable for 6h, take out the catalyst after cooling down to room temperature, and obtain the sulfided catalyst C2.

Example 3

Weigh 80g of phosphoric acid and put it in a beaker, add 20g of deionized water, stir evenly to obtain a phosphoric acid solution for use; weigh 20g of coal-based activated carbon and put it in a 500ml round bottom flask, then add the prepared phosphoric acid solution, and keep the temperature at 80°C Stir in a water bath at 400r/min for 2 hours, then use a large amount of deionized water to wash the activated carbon, filter it several times until the pH value of the filtrate is between 6-7, and then dry it in an oven at 120°C for 8 hours to obtain acidified activated carbon, which is designated as S-3 .

Measure the water absorption rate of carrier S-3 to 0.90ml/g; weigh 10g of S-2 prepared in Example 1, 4.713g of nickel nitrate hexahydrate, 1.214g of niobium oxalate and 9.5g of deionized water, and add them to a 20ml glass beaker. After stirring for 1 min on a magnetic stirrer, the metal precursor was obtained; the metal precursor was impregnated on the surface of S-3 by equal-volume impregnation method, placed at room temperature for 12 h to dry, then dried in an oven at 100 °C for 6 h, and then placed in a Calcined at 350°C for 8 hours in a muffle furnace to obtain the calcined activated carbon, denoted as B3.

Take 5ml of B3 and place it in a fixed bed reactor, and carry out reduction treatment in a hydrogen atmosphere, first pass hydrogen (30ml/min) until the reaction pressure is 2MPa, then start to increase the temperature (2°C/min) to 350°C, and stabilize for 8h , after cooling down to room temperature, the catalyst was taken out to obtain the reduced catalyst C3.

Example 4

Weigh 2g of B1 prepared in Example 1 and place it in a fixed-bed reactor, carry out reduction treatment in a hydrogen atmosphere, first feed hydrogen (100ml/min), until the reaction pressure is 1MPa, then start to heat up (2°C/min ) to 450°C, reduce for 4 hours, then lower the temperature to 200°C, then pump in 3wt% triphenylphosphine cyclohexane solution, space velocity 2h ^-1 , hydrogen oil ratio 300:1, heat up to 300°C, stabilize for 12h, The reaction pressure was 3MPa, and the phosphated catalyst C4 was obtained.

Comparative example 1

Prepare reduced Ni/C catalyst according to prior art: measure the water absorption rate of coconut shell activated carbon 0.90ml/g, weigh 10g carrier AC, 7.0079g nickel nitrate hexahydrate and 9.0g deionized water. Add nickel nitrate hexahydrate and deionized water into a 20ml glass beaker, place on a magnetic stirrer and stir for 1 min to obtain a metal precursor; impregnate the metal precursor on the surface of the carrier AC by an equal volume impregnation method, and place it at room temperature for 12 hours to dry After drying, it was dried in an oven at 120°C for 2 hours, and then calcined in a muffle furnace at 400°C for 4 hours to obtain catalyst D1.

Measure 5ml of D1 catalyst and place it in a fixed-bed reactor, feed hydrogen gas (30ml/min) until the reaction pressure is 1MPa, then start to raise the temperature (2°C/min) to 400°C, keep it stable for 4 hours, and take out the catalyst after cooling down to room temperature , to obtain the reduced catalyst E1.

Comparative example 2

Prepare reduced Ni/Al ₂ O ₃ catalyst according to the prior art: measure the water absorption rate of carrier γ-Al ₂ O ₃ to 0.65ml/g, weigh 10g carrier Al ₂ O ₃ , 7.0079g nickel nitrate hexahydrate and 6.5g Deionized water. Add nickel nitrate hexahydrate and deionized water into a 20ml glass beaker, place it on a magnetic stirrer and stir for 1 min to obtain a metal precursor, and use an equal volume impregnation method to impregnate the metal precursor on the surface of the carrier Al ₂ O ₃ , at room temperature After being left to dry for 12 hours, it was dried in an oven at 120°C for 2 hours, and then calcined in a muffle furnace at 400°C for 4 hours to obtain catalyst D2.

Measure 5ml of D2 catalyst and place it in a fixed-bed reactor, feed hydrogen gas (30ml/min) until the reaction pressure is 1MPa, then start to raise the temperature (2°C/min) to 400°C, stabilize for 4h, and take out the catalyst after cooling down to room temperature , to obtain the reduced catalyst E2.

Comparative example 3

Prepare the reduced Ni/USY catalyst according to the prior art: measure the water absorption rate of carrier USY molecular sieve to 0.62ml/g, weigh 10g carrier USY molecular sieve, 7.0079g nickel nitrate hexahydrate and 6.2g deionized water. Add nickel nitrate hexahydrate and deionized water into a 20ml glass beaker, place it on a magnetic stirrer and stir for 1 minute to obtain a metal precursor, and use an equal volume impregnation method to impregnate the metal precursor on the surface of the carrier USY molecular sieve, and place it at room temperature for 12 hours After air-drying, it was dried in an oven at 120°C for 2 hours, and then calcined in a muffle furnace at 400°C for 4 hours to obtain catalyst D3.

Measure 5ml of D3 catalyst and place it in a fixed-bed reactor, feed hydrogen gas (30ml/min) until the reaction pressure is 1MPa, then start to raise the temperature (2°C/min) to 400°C, keep it stable for 4 hours, and take out the catalyst after cooling down to room temperature , to obtain the reduced catalyst E3.

Comparative example 4

Prepare reduced state Pt/acidified activated carbon catalyst according to the prior art: measure the water absorption rate of S-1 prepared in Example 2 to 0.95ml/g, weigh 10g carrier S-1, 0.2654g chloroplatinic acid hexahydrate and 9.5g ionized water. Add chloroplatinic acid hexahydrate and deionized water into a 20ml glass beaker, place it on a magnetic stirrer and stir for 1 min to obtain the metal precursor solution of chloroplatinic acid; use the equal volume impregnation method to impregnate the metal precursor solution in S-1 The surface was placed at room temperature for 12 hours to dry, then dried in an oven at 120°C for 2 hours, and then calcined in a muffle furnace at 400°C for 4 hours to obtain catalyst D1.

Measure 5ml of D1 catalyst and place it in a fixed-bed reactor, feed hydrogen gas (30ml/min) until the reaction pressure is 1MPa, then start to raise the temperature (2°C/min) to 400°C, keep it stable for 4 hours, and take out the catalyst after cooling down to room temperature , to obtain the reduced catalyst E4.

Experimental example 1

This experimental example is to verify the catalytic effect of the catalysts prepared in Examples 1-4 and Comparative Examples 1-4 in the hydrodeoxygenation reaction of lye guaiacol, and the results are shown in Table 1.

The reaction conditions are: take 1g catalyst, 0.261g NaOH, 20g deionized water and 5g guaiacol; react in a 100ml high-pressure reactor, replace the air in the reactor with nitrogen, and feed hydrogen to make the initial pressure at 2.5Mpa; the temperature was raised to 300°C at 10°C/min, and after 150 minutes of reaction, it was naturally cooled down to room temperature; the catalyst was separated by centrifugation, and the reaction product was analyzed by gas chromatography. The results are shown in Table 2 below.

Catalyst physicochemical property table before and after table 1 reaction

As can be seen from Table 1, the acid content on the surface of activated carbon C1-C4 catalyst and E1 catalyst after acid treatment was found to be significantly increased from 0.37mmol/g to 2.8-2.95mmol/g after acid treatment. . Comparing the C1 and E1 catalysts, it can be seen from Figure 6 that compared with the unacidified catalyst E1, the intensity of the characteristic peaks corresponding to the acidic groups such as hydroxyl groups on the surface of the catalyst C1 after the acidification treatment is significantly improved, and the catalyst surface after the acidification treatment The increase in the amount of acid originates from the increase in the number of hydroxyl, carboxyl, and lactone groups, thus providing acidic active sites for catalytic hydrodeoxygenation, thereby effectively increasing the hydrodeoxygenation activity of the catalyst. Contrast the pore structure properties and acid properties of C1-C4 before and after the reaction and find that the average pore diameter, pore volume, specific surface area and surface acid content of the catalyst after the reaction under alkaline conditions do not change much. Good stability under the conditions. Comparing the E2 and E3 catalysts before and after the reaction, it was found that after the reaction under alkaline conditions, the pore size of the catalyst supported by Al ₂ O ₃ and USY molecular sieve became significantly larger, the specific surface area decreased significantly, and the skeleton structure of the catalyst was severely damaged , leading to serious metal loss on the catalyst surface, and a significant decrease in the metal loading on the catalyst surface.

The crystal phase structure properties of the C1 catalyst before and after the reaction are shown in Figure 2. The crystal phase structure of the C1 catalyst is not damaged after the catalytic reaction in alkaline conditions, and the crystal phase structure of the C1 catalyst is highly stable in alkaline solution.

The pore structure properties of the C1 catalyst before and after the reaction are shown in Figure 3. The pore structure of the C1 catalyst is not damaged after the catalytic reaction in alkaline conditions, and the skeleton structure of the C1 catalyst is highly stable in alkali solution.

The metal crystal microstructure on the surface of the C1 catalyst before and after the reaction is shown in Figure 4. After the catalytic reaction in alkaline conditions, the metal on the surface of the C1 catalyst still maintains a reduced metal crystal structure, and it is uniformly dispersed without agglomeration. The metal on the surface of the C1 catalyst Crystals are highly stable in lye.

The acid properties of the surface of the C1 catalyst before and after the reaction are shown in Figure 5. After the catalytic reaction in alkaline conditions, the type and number of acidic groups on the surface of the C1 catalyst are not reduced, and the C1 catalyst can maintain a certain acidity in the lye.

It can be seen from Figures 2-5 that the physical and chemical properties of the catalyst supported by acidic activated carbon are not destroyed under alkaline conditions, and the catalyst has good stability.

Table 2 reaction product by gas chromatography analysis result

catalyst Conversion rate of guaiacol Hydrocarbon Product Yield C1 100% 27.0% C2 100% 20.5% C3 100% 45.1% C4 100% 33.2% E1 98.80% 2.5% E2 29.20% 1.1% E3 23.50% 2.3%

By analyzing the conversion rate of guaiacol after alcoholysis and hydrogenation and the yield of hydrocarbon products to compare the alcoholysis hydrogenation activity and catalyst hydrodeoxygenation activity of the catalyst, see the above table 2 for details. The results of alcoholysis and hydrogenation of guaiacol showed that although the conversion rate of guaiacol on the two catalysts was similar, the yield of hydrocarbon products on the activated carbon catalyst C1 after acidification was significantly higher than that of E1. By comparing the results of alcoholysis and hydrogenation of guaiacol on C1-E3 catalysts, it was found that compared with the E2 catalyst supported by Al ₂ O ₃ and the E3 catalyst supported by USY molecular sieve, the catalyst supported by acidified activated carbon had the Higher hydrocarbon yields. That is, the catalyst prepared by the present invention not only ensures high stability under alkaline conditions, but also ensures that certain acidic sites exist on the surface of the catalyst, providing effective reactive centers for the generation of hydrocarbon products.

Experimental example 2

This experimental example is the catalytic reaction of the C4 catalyst synthesized in Example 4 and the E4 catalyst synthesized in Comparative Example 4 in the hydrodeoxygenation reaction using papermaking black liquor as raw material. The results are shown in Table 3.

The reaction conditions are: weigh 8g of catalyst, 30g of papermaking black liquor, 80g of methanol and 90g of dodecane; react in a 500ml high-pressure reactor, replace the air in the reactor with nitrogen, and feed hydrogen to make the initial pressure at 2.5Mpa . The temperature was raised to 300°C at 10°C/min, and after 20 hours of reaction, it was naturally cooled down to room temperature. The catalyst was separated by centrifugation, and the liquid was acidified to precipitate residual lignin solids. The liquid reaction product was analyzed by gas chromatography. The analysis results are shown in Table 3 below. The residual lignin solids were characterized by elemental analysis. The characterization results are shown in Table 4 below.

Table 3 liquid reaction product by gas chromatography analysis result

catalyst Black liquor lignin conversion rate Hydrocarbon Product Yield C4 66.9% 27.8% E4 2.3% 0.1%

Table 4 Residual lignin solids are characterized by elemental analysis

catalyst C/mol% H/mol% O/mol% N/mol% S/mol% H/C O/C blank comparison 25.9 41.9 31.2 0.1 0.7 1.6 1.2 C4 36.6 47.6 13.7 0.2 1.9 1.3 0.4 E4 26.0 42.0 31.2 0.1 0.7 1.6 1.2

The above Table 3 and Table 4 compare the alcoholysis hydrogenation activity of the catalyst by analyzing the conversion rate of black liquor lignin after alcoholysis hydrogenation, the yield of hydrocarbon products and the O element content of residual lignin. The comparison results of the alcoholysis hydrogenation reaction and the blank showed that the C4 catalyst had good catalytic activity in the alcoholysis hydrogenation reaction using papermaking black liquor as raw material, effectively obtained hydrocarbon products, and at the same time reduced the oxygen content of lignin . By comparing the alcoholysis hydrogenation reaction of lignin on the C4 catalyst with the blank comparison results, it was found that the activity of the E4 catalyst was extremely low in the alcoholysis hydrogenation reaction using the papermaking black liquor as raw material, and the Pt precious metal was rapidly poisoned by the S in the papermaking black liquor. That is, the papermaking black liquor lignin alcoholysis hydrodeoxygenation treatment catalyst prepared by the present invention is economical, alkali resistance, sulfur resistance, high stability and high alcoholysis hydrogenation reaction in the papermaking black liquor as raw material. Hydrogenation activity.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the essential technical content of the present invention. The essential technical content of the present invention is broadly defined in the scope of the claims of the application, and any technical entity completed by others or method, if it is exactly the same as that defined in the scope of the claims of the application, or an equivalent change, it will be deemed to be included in the scope of the claims.

Claims (10)

1. a preparation method of papermaking black liquor lignin conversion catalyst, is characterized in that: comprise the following steps: (1) Washing the acid solution and the carrier after thermal reaction until the pH value of the washing solution is between 6-7 to obtain the acidified carrier; (2) impregnating the metal precursor on the surface of the acidified carrier prepared in step (1) to obtain a metal-loaded carrier; (3) Drying and calcining the metal-loaded carrier obtained in step (2). 2. preparation method according to claim 1, is characterized in that: the acid solution described in step (1) is the hydrochloric acid of 1-80wt%, phosphoric acid, sulfuric acid or nitric acid, and described carrier is wooden gac, fruit shell Activated carbon, coconut shell activated carbon, coal activated carbon or petroleum coke activated carbon, the specific surface area of the carrier is 700-2000m ² /g, and the mass ratio of the carrier to the acid solution is 1:2-10. 3. preparation method according to claim 1, is characterized in that: the acid solution described in step (1) is the nitric acid of 2.5wt% or sulfuric acid, and described carrier is coconut shell activated carbon, and described carrier and acid solution The mass ratio is 1:10. 4. The preparation method according to claim 1, characterized in that: the temperature of the thermal reaction in step (1) is 40-80°C, and the time is 2-10h. 5. The preparation method according to claim 1, characterized in that: the metal loaded on the carrier surface of the metal described in the step (2) is selected from vanadium, molybdenum, bismuth, nickel, iron, antimony, tungsten, copper One or both of , iron, niobium, chromium, magnesium, zinc and aluminum. 6. The preparation method according to claim 1, characterized in that: the drying and roasting conditions in step (3) are: after drying at 80-120°C for 2-12h, then roasting at 300-550°C for 2-8h . 7. preparation method according to claim 1, is characterized in that: also comprise step (4), the carrier after the roasting that obtains in step (3) is carried out reduction, vulcanization or phosphating treatment: The reduction treatment conditions are as follows: the reduction temperature is 150-500°C, the reducing atmosphere is _H2 or _H2 /Ar mixed gas, the reduction time is 1-6h, and the reduced catalyst is obtained after treatment; The vulcanization treatment conditions are as follows: the vulcanization temperature is 250-500° C., the vulcanization agent is one of thiourea, H ₂ S, DMDS and CS ₂ , the vulcanization time is 1-6 hours, and the vulcanized catalyst is obtained after treatment; The phosphating treatment conditions are: the phosphating temperature is 250-500°C, the phosphating agent is one of triphenylphosphine, phosphoric acid, ammonium dihydrogen phosphate, diamine hydrogen phosphate and urea phosphate, and the phosphating time is 1 -6h, the phosphated catalyst was obtained after treatment. 8. A catalyst prepared by the preparation method according to any one of claims 1-7. 9. The catalyst according to claim 8, characterized in that the catalyst has a surface area of 700-1000m ² /g, a pore volume of 0.3-0.5cm ³ /g, an average pore diameter of 0.5-2nm, and a total surface acid content of 1-8mmol/g. 10. An application of the catalyst according to claim 8 or 9 in catalytic conversion of papermaking black liquor lignin.

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