阅读说明：本技术 一种磺化介孔碳纳米纤维材料及其制备方法与应用 (Sulfonated mesoporous carbon nanofiber material and preparation method and application thereof ) 是由 杨英 邵帅 郭尚卫 郝世杰 于 2019-11-08 设计创作，主要内容包括：本发明提供一种磺化介孔碳纳米纤维材料及其制备方法与应用。该磺化介孔碳纳米纤维材料的制备方法包括：将生物质纤维进行预氧化处理；将预氧化处理后的生物质纤维使用含氯离子的铁盐溶液进行浸渍得到产物A；将产物A在500℃以上进行热解,得到产物铁掺杂的碳纳米纤维B；将产物B进行磺化处理得到磺化介孔碳纳米纤维材料。该磺化介孔碳纳米纤维材料可应用于纤维素水解反应中。本发明制备得到的磺化介孔碳纳米纤维材料是一种固体酸催化材料能够有效催化纤维素水解制备葡萄糖,且具备高葡萄糖收率、高比表面积、高孔隙率等优势。(The invention provides a sulfonated mesoporous carbon nanofiber material and a preparation method and application thereof. The preparation method of the sulfonated mesoporous carbon nanofiber material comprises the following steps: carrying out pre-oxidation treatment on the biomass fibers; dipping the biomass fiber subjected to pre-oxidation treatment by using ferric salt solution containing chloride ions to obtain a product A; pyrolyzing the product A at the temperature of more than 500 ℃ to obtain a product iron-doped carbon nanofiber B; and sulfonating the product B to obtain the sulfonated mesoporous carbon nanofiber material. The sulfonated mesoporous carbon nanofiber material can be applied to cellulose hydrolysis reaction. The sulfonated mesoporous carbon nanofiber material prepared by the invention is a solid acid catalytic material, can effectively catalyze cellulose hydrolysis to prepare glucose, and has the advantages of high glucose yield, high specific surface area, high porosity and the like.)

1. A preparation method of a sulfonated mesoporous carbon nanofiber material comprises the following steps:

1) carrying out pre-oxidation treatment on the biomass fibers;

2) dipping the biomass fiber subjected to preoxidation treatment by using ferric salt containing chloride ions to obtain a product A;

3) pyrolyzing the product A at the temperature of more than 500 ℃ to obtain a product B;

4) and sulfonating the product B to obtain the sulfonated mesoporous carbon nanofiber material.

2. The production method according to claim 1,

the biomass fibers are provided by at least one of carbon cloth, non-woven wet tissue and rag; preferably, the biomass fibers are provided by a nonwoven wet wipe;

the ferric salt containing chloride ions comprises at least one of ferrous chloride and ferric chloride; preferably, the chloride ion-containing iron salt is ferric chloride.

3. The production method according to claim 1, wherein the pre-oxidation treatment is performed using an acid;

preferably, the acid comprises at least one of hydrochloric acid, nitric acid and sulfuric acid;

preferably, the acid is an acid solution with the concentration of 1-5 mol/L.

4. The production method according to claim 1 or 3,

the temperature of the pre-oxidation treatment is 20-80 ℃, and preferably 60 ℃; the time of the pre-oxidation treatment is 1-5 h.

5. The preparation method according to claim 1, wherein the mass ratio of the biomass fibers subjected to the pre-oxidation treatment to the iron element in the ferric salt containing the chloride ions is 1:1-5: 1.

6. The method as claimed in claim 1, wherein the pyrolysis temperature is 500-800 ℃; the pyrolysis time is 1-8 h;

preferably, the rate of temperature increase to pyrolysis temperature is 2-20 deg.C/min.

7. The production method according to claim 1, wherein sulfonation is carried out with an acid;

preferably, the sulfonating acid is chlorosulfonic acid; more preferably, sulfonation is carried out by dispersing the product B in an organic solvent environment, dichloromethane, and adding chlorosulfonic acid; further preferably, the organic solvent is at least one of chloroform, dichloroethane and dichloromethane;

preferably, the sulfonation time is from 5 to 20 hours.

8. The method according to claim 1, wherein iron is removed by acid after sulfonation; preferably, the acid is hydrofluoric acid.

9. Sulfonated mesoporous carbon nanofibrous material prepared by the method of preparation of sulfonated mesoporous carbon nanofibrous material according to any of claims 1-8;

preferably, the acid content of the sulfonated mesoporous carbon nanofiber material is 1.4-2.0 mmol/g;

preferably, the specific surface area of the sulfonated mesoporous carbon nanofiber material is 37-384m²/g；

Preferably, the pore volume of the sulfonated mesoporous carbon nanofiber material is 0.03-0.200cm³/g；

Preferably, the fibers in the sulfonated mesoporous carbon nanofiber material have a one-dimensional fiber morphology;

preferably, the aspect ratio of the fibers in the sulfonated mesoporous carbon nanofiber material is 5-11 on average.

10. Use of the sulfonated mesoporous carbon nanofiber material of claim 9 in cellulose hydrolysis reactions;

preferably, the cellulose hydrolysis reaction is cellulose hydrolysis to prepare glucose;

preferably, the cellulose is microcrystalline cellulose.

Technical Field

The invention belongs to the technical field of carbon nano materials, and relates to a sulfonated mesoporous carbon nano fiber material, and a preparation method and application thereof.

Background

In recent years, with rapid economic development, petrochemical resources such as petroleum have been increasingly consumed and are being exhausted. Meanwhile, the non-renewable nature of petrochemical resources and the accompanying environmental pollution problem have made the world's energy strategy focus on the development and utilization of clean and renewable energy. Among a plurality of renewable energy sources, the biomass energy storage capacity is large and zero emission of carbon dioxide can be realized. Therefore, the preparation of fuel or chemicals by using biomass as a raw material is an important way for solving the energy crisis and realizing energy regeneration.

Cellulose is one of the most abundant renewable biomass resources on the earth, can be hydrolyzed at low temperature (180 ℃) to generate sugar micromolecules, and then is further converted into chemical products such as ethanol, 5-hydroxymethyl furfural, sorbitol and levulinic acid and fuel intermediates. However, the cellulose structure is very stable and difficult to convert, so that the development of a high-efficiency cellulose hydrolysis catalyst has important significance for the utilization of biomass cellulose.

Currently, the main methods for achieving cellulose hydrolysis are enzyme catalysis and acid catalysis. Enzymatic hydrolysis refers to the hydrolysis of cellulose by the action of cellulase enzymes under milder conditions. The enzyme hydrolysis reaction conditions are mild, the selectivity is high, but the method has the problems of high cost, low efficiency, large enzyme dosage and the like (Uju, Aya Nakamoto, Yasuhim Shoda, et al, Low longpoint pyridine ionic liquid pretreatment for enhancing enzyme catalysis and Technology,2013,135(10): 103-108). Acid hydrolysis uses mainly mineral acids, e.g. H₂SO₄，HCl，HNO₃HF, etc., catalyze the hydrolysis of cellulose to glucose. High cellulose content by acid hydrolysisEfficient conversion and high yield of glucose, but the large-scale use of mineral acids has problems of severe corrosion of equipment, difficulty in product separation, and generation of a large amount of wastewater (congratulation. research on selectivity of cellulose acid hydrolysis and its control technology. university of shanxi science and technology, 2014). Solid acid catalytic materials have recently received increasing attention from researchers because of their low corrosion to cellulose hydrolysis reaction equipment and their easy separation of products. At present, solid acid catalytic materials for cellulose hydrolysis include metal oxides, silicon-based solid acids, and sulfonated carbon-based solid acids, and the like. Preparation of transition metal oxide LiNbMoO by Domen et al through high temperature roasting₆Then with H⁺Replacement of LiNbMoO₆Metal ion Li of⁺To prepare HNbMoO₆(Atsushi Takagaki, Caio Tagusawa, Kazunari domino. glucose reduction from polysaccharides using layer division method and extruded nanosheets as a water-based solified catalyst, Chemistry Communication,2008,42: 5363-. The catalyst has high acid density, but because the size of the cellulose is greatly different from the spacing of the metal oxide layers, the acid sites can not be fully utilized, and the cellulose conversion rate is low. Nakajima et al use a nano-casting method to dip furfuryl alcohol into the mesoporous pores of the aluminum modified SBA-15, and prepare the carbon-silicon mesoporous sulfonic acid catalytic material through carbonization and gas phase sulfonation (Kiyotaka Nakajima, Mai Okamura, Junko N.Kondo, Kazunari Domen, Takashi Tatsumi, Shigenobu Hayashi, Michikazu Hara.Amorphous carboning sulfonic acid groups in meso-porous silicon as a selective catalyst, chem.Mater.2009,21: 186-193). The solid acid catalytic material has high surface area and regular pore channels, but the acid content is low, the preparation process is complex, and large-scale production cannot be realized. Sulfonated carbon-based solid acids have high cycle stability and cheap raw materials, so the sulfonated carbon-based solid acids have wide practicability (Michikazu Hara. Biomassconversion by a solid acid catalyst, Energy environ. Sci.,2010,3(5): 601-607). The traditional sulfonated carbon-based solid acid catalytic material is mainly prepared by sulfonating fuming sulfuric acid, concentrated sulfuric acid or chlorosulfonic acid by using biomass resources such as glucose, starch, sucrose and the like or pulp waste as a carbon source. But the grain is taken as the raw material, has the defects of 'land competition with agriculture' and 'food competition with people' and cannot realize sustainable development; paper pulp is used as a carbon source,the method has the advantages of cheap raw materials and wide sources, but the thermal stability of the paper pulp is poor, the morphology of the carbon-based solid acid catalytic material cannot be controlled, the pore structure is insufficient, and the cellulose hydrolysis efficiency is poor.

From the above, it can be seen that the development of a sulfonated carbon-based solid acid catalytic material with high specific surface area, high porosity, low cost and strong morphology selectivity for preparing glucose through cellulose hydrolysis faces a great challenge.

Disclosure of Invention

The invention aims to provide a preparation method of a sulfonated mesoporous carbon nanofiber material, the material prepared by the preparation method is a solid acid catalytic material, can effectively catalyze cellulose hydrolysis to prepare glucose, and has the advantages of high glucose yield, high specific surface area, high porosity and the like.

In order to achieve the above object, the present invention provides a preparation method of a sulfonated mesoporous carbon nanofiber material (as shown in fig. 1), wherein the preparation method comprises the following steps:

1) carrying out pre-oxidation treatment on the biomass fibers;

2) dipping the biomass fiber subjected to pre-oxidation treatment by using ferric salt solution containing chloride ions to obtain a product A which is recorded as Fe/BF-X;

3) pyrolyzing the product Fe/BF-X at the temperature of more than 500 ℃ to obtain a product B (belonging to iron-doped carbon nanofiber) which is marked as Fe/CNF-X-T;

4) and sulfonating the product B to obtain the sulfonated mesoporous carbon nanofiber material which is marked as SMCNF-X-T.

In the above production method, preferably, the ferric salt containing chloride ions includes at least one of ferrous chloride and ferric chloride; more preferably, the chloride ion-containing iron salt is ferric chloride.

In the above preparation method, preferably, the biomass fiber is provided by at least one of a carbon cloth, a nonwoven wet wipe and a rag; preferably, the biomass fibers are provided by a nonwoven wet wipe. The main component of the non-woven fabric wet tissue is non-woven fabric, the raw materials of the non-woven fabric wet tissue comprise chemical fibers (such as terylene, polypropylene fiber, acrylic fiber and the like) and natural plant fibers (such as hemp, coconut palm fiber, orange peel and the like), the non-woven fabric wet tissue is a wet tissue blended by the chemical fibers and the natural plant fibers, and belongs to the field of biomass fibers. The high thermal stability of the biomass fibers provided by at least one of carbon cloth, non-woven wet tissue, rag and the like is beneficial to keeping the good one-dimensional fiber morphology of the prepared sulfonated mesoporous carbon nanofiber material, and greatly avoiding the collapse and aggregation of a fiber network structure into blocks; the prepared sulfonated mesoporous carbon nanofiber with the one-dimensional fiber morphology has a higher length-diameter ratio, the reaction path is further shortened, and the hydrolysis reaction is accelerated.

In the above production method, preferably, the biomass fiber is washed with an organic solvent and an inorganic solvent before use, respectively; wherein, the inorganic solvent can be at least one of ethanol and acetone, but is not limited thereto; the organic solvent may be selected from water, but is not limited thereto; the washing may be performed by ultrasonic washing, but is not limited thereto.

In the above production method, preferably, the pre-oxidation treatment is performed using an acid; more preferably, the acid comprises at least one of hydrochloric acid, nitric acid and sulfuric acid. Among them, the acid is preferably used in a concentration of 1 to 5 mol/L.

In the above production method, preferably, the temperature of the pre-oxidation treatment is 20 to 80 ℃; more preferably 60 deg.c.

In the above production method, the time of the pre-oxidation treatment is preferably 1 to 5 hours, more preferably 1 hour.

In a specific embodiment, the biomass fiber is soaked in 1-5mol/L acid solution and is subjected to pre-oxidation treatment for 1-5 hours at the temperature of 20-80 ℃ to obtain the biomass fiber after the pre-oxidation treatment. In another specific embodiment, the biomass fiber is soaked in 2mol/L acid solution and is subjected to pre-oxidation treatment for 1 hour at the temperature of 60 ℃, so that the biomass fiber after the pre-oxidation treatment is obtained.

In the preparation method, the mass ratio of the biomass fibers after the pre-oxidation treatment to the iron element in the ferric salt containing the chloride ions is preferably 1:1-5:1, and more preferably 5: 1.

In the above production method, it is preferable that the product Fe/BF-X is dried before being subjected to pyrolysis.

In the above preparation method, preferably, in the step 2), the temperature of the pyrolysis is 500-.

In the above preparation method, preferably, the pyrolysis time is 1 to 8 hours.

In the above production method, preferably, the temperature increase rate up to the pyrolysis temperature is 2 to 20 ℃/min.

In a specific embodiment, the product Fe/BF-X is heated to above 500 ℃ at the speed of 2-20 ℃/min and kept at the constant temperature for 1-8h for pyrolysis.

In another embodiment, the product Fe/BF-X is pyrolyzed by raising the temperature to 500 ℃ at a rate of 5 ℃/min and maintaining the temperature for 2 hours.

In the above production method, preferably, sulfonation is carried out using an acid; more preferably, the sulfonating acid is chlorosulfonic acid; further preferably, sulfonation is carried out by dispersing the product Fe/CNF-X-T in an organic solvent environment, namely dichloromethane, and adding chlorosulfonic acid, wherein the organic solvent can be at least one of chloroform, dichloroethane and dichloromethane, but is not limited thereto. Since the chlorosulfonic acid reaction environment must be anhydrous, the chlorosulfonic acid sulfonation reaction is typically carried out in an organic solvent environment. Compared with other sulfonating agents, the acid sulfonation has the advantages of short sulfonation time, small material feeding amount, high sulfonation degree, environmental protection and the like. Compared with other acid sulfonating agents, chlorosulfonic acid sulfonation has the advantages of strong reactivity, room-temperature sulfonation, mild conditions and cost saving.

In the above preparation method, preferably, the sulfonation time is 5 to 20 hours.

In the above preparation method, preferably, iron is removed by using an acid after sulfonation; more preferably, the acid is hydrofluoric acid.

In one embodiment, sulfonation is carried out by dispersing the product Fe/CNF-X-T in methylene chloride and adding an acid for sulfonation.

In a specific embodiment, the product Fe/CNF-X-T is dispersed into dichloromethane, acid is added for sulfonation, and then iron is removed by acid to obtain the sulfonated mesoporous carbon nanofiber material SMCNF-X-T.

In a specific embodiment, the product Fe/CNF-X-T is dispersed in dichloromethane, sulfonated acid chlorosulfonic acid is added for sulfonation for 12h, then hydrofluoric acid is added for stirring for 2h to remove iron, and the sulfonated mesoporous carbon nanofiber material SMCNF-X-T is obtained.

The invention also provides a sulfonated mesoporous carbon nanofiber material prepared by the preparation method of the sulfonated mesoporous carbon nanofiber material.

The acid content of the sulfonated mesoporous carbon nanofiber material is preferably 1.4-2.0mmol/g, and more preferably 1.72 mmol/g.

The specific surface area of the sulfonated mesoporous carbon nanofiber material is preferably 37-384m²Per g, more preferably 384m²/g；

The total pore volume of the sulfonated mesoporous carbon nanofiber material is preferably 0.03-0.200cm³A ratio of 0.182 m/g is more preferable³/g。

The sulfonated mesoporous carbon nanofiber material preferably has a one-dimensional fiber morphology.

The aspect ratio of the fibers in the sulfonated mesoporous carbon nanofiber material is preferably 5 to 11 on average, and more preferably 9.

The invention also provides an application of the sulfonated mesoporous carbon nanofiber material in cellulose hydrolysis reaction. The catalyst can be particularly used for the hydrolysis reaction of microcrystalline cellulose.

In the above application, preferably, the cellulose hydrolysis reaction is hydrolysis of cellulose to produce glucose.

In the above application, preferably, the cellulose is microcrystalline cellulose.

According to the preparation method of the sulfonated mesoporous carbon nanofiber, provided by the invention, the surface of the biomass fiber is provided with rich functional groups through pre-oxidation treatment, and then ferric salt containing chloride ions is used for dipping to enable Cl^-Adsorbing the carbon fiber on the surface of the fiber through the action of functional groups on the surface of the fiber, and roasting at high temperature to generate C-Cl bonds on the surface of the carbon material. The strong interaction of the C-Cl bond of the sulfonated mesoporous carbon nanofiber and the cellulose-OH adsorbs the cellulose on the surface of the sulfonated mesoporous carbon nanofiber, and simultaneously enriches-SO₃H group promoted cellulose fast waterDissolving and sulfonating C-Cl bond and-SO on the surface of the mesoporous carbon nanofiber₃The H groups act synergistically to cause the sulfonated mesoporous carbon nanofibers to exhibit high cellulose hydrolysis catalytic activity, resulting in high glucose yields (up to 66% in one embodiment).

According to the preparation method of the sulfonated mesoporous carbon nanofiber, the pre-oxidized biomass fiber is used as a carbon source, ferric salt containing chloride ions is soaked, the ferric salt containing the chloride ions, which is biocompatible and environment-friendly, is converted into an oxide template, a rich pore structure is constructed through sulfonation, the sulfonated mesoporous carbon nanofiber has a large specific surface area and sufficient acid sites, and rapid hydrolysis of cellulose can be realized.

In a word, the technical scheme provided by the invention adopts the biomass fibers without using an expensive carbon source to prepare the sulfonated mesoporous carbon fiber material with high specific surface area and developed pore structure, the preparation method has simple and economic steps, and the specific surface area and the pore diameter of the material can be adjusted by adjusting the roasting temperature. The prepared sulfonated mesoporous carbon fiber material is used for catalyzing cellulose hydrolysis, cellulose is completely converted, the glucose yield is high (up to 66% in a specific implementation mode), and the sulfonated mesoporous carbon fiber material has a good market application prospect.

Drawings

FIG. 1 is a schematic flow chart of a preparation method of a sulfonated mesoporous carbon nanofiber material provided by the invention.

FIG. 2A is a SEM image of Fe/BF-1/5 provided in example 1 at 500 times magnification.

FIG. 2B is an SEM 300 Xmagnification of Fe/CNF-1/5-500 provided in example 1.

FIG. 2C is an SEM image of SMCNF-1/5-500 at 600X magnification as provided in example 1.

FIG. 3A is a surface distribution diagram of the C element in Fe/CNF-1/5-500 provided in example 1.

FIG. 3B is a surface distribution diagram of the S element in Fe/CNF-1/5-500 provided in example 1.

FIG. 3C is a surface distribution diagram of the O element in Fe/CNF-1/5-500 provided in example 1.

FIG. 3D is a surface distribution diagram of Fe element in Fe/CNF-1/5-500 provided in example 1.

FIG. 3E is a distribution plot of the area of the C element in SMCNF-1/5-500 provided in example 1.

Fig. 3F is a surface distribution diagram of the S element in SMCNF-1/5-50 provided in example 1.

FIG. 3G is a surface distribution diagram of the O element in SMCNF-1/5-500 provided in example 1.

FIG. 3H is a plot of the areal distribution of the Fe element in SMCNF-1/5-500 provided in example 1.

Figure 4 is a high energy X-ray diffraction (HE-XRD) pattern of SMCNF-1/5-500 provided in example 1.

FIG. 5A is an S2p X-ray photoelectron spectrum of SMCNF-1/5-500 provided in example 1.

FIG. 5B is the Fe2p X-ray photoelectron spectrum of Fe/BF-1/5, Fe/CNF-1/5-500 and SMCNF-1/5-500 provided in example 1.

FIG. 5C is a Cl2p X-ray photoelectron spectrum of SMCNF-1/5-500 provided in example 1.

FIG. 6A is N of SMCNF-1/5-500 provided in example 1₂Adsorption/desorption isotherm plot.

FIG. 6B is a graph of the mesoporous pore size distribution of SMCNF-1/5-500 provided in example 1.

FIG. 7 is a bar graph of the total acid content of SMCNF-1/5-500 versus sulfonic acid content provided in example 1.

FIG. 8 is an X-ray absorption fine structure spectrum (EXAFS) of SMCNF-1/5-500 provided in example 1, SMCNF-1/5-650 provided in example 2, and SMCNF-1/5-350 provided in comparative example 2.

FIG. 9 is a graph of the results of different SMCNF-X-T catalyzed cellulolytic hydrolysis.

FIG. 10A is a magnified high power microscope image of the SMCNF-1/5-500 material provided in example 1.

Fig. 10B is a high power microscope magnified view of the sulfonated mesoporous carbon fiber material provided in example 3.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.