CN110642814B - Method for preparing furfural by co-pyrolysis - Google Patents
Method for preparing furfural by co-pyrolysis Download PDFInfo
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D307/38—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
- C07D307/40—Radicals substituted by oxygen atoms
- C07D307/46—Doubly bound oxygen atoms, or two oxygen atoms singly bound to the same carbon atom
- C07D307/48—Furfural
- C07D307/50—Preparation from natural products
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D307/38—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
- C07D307/40—Radicals substituted by oxygen atoms
- C07D307/46—Doubly bound oxygen atoms, or two oxygen atoms singly bound to the same carbon atom
- C07D307/48—Furfural
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Abstract
The invention belongs to the field of biomass energy utilization, and particularly relates to a method for preparing furfural by co-pyrolysis. According to the invention, biomass rich in xylose units is used as a raw material for preparing furfural, the raw material is mixed and contacted with oxalic acid, fast co-pyrolysis is carried out at 200-500 ℃ under an anaerobic condition, and pyrolysis gas is condensed to room temperature to obtain a furfural-rich liquid product. The oxalic acid involved in the method is common and easy to obtain, has low price, plays a role in catalyzing the decomposition of raw materials to form furfural in the co-pyrolysis process, and simultaneously decomposes by itself without remaining in solid-phase, liquid-phase or gas-phase pyrolysis products, so the co-pyrolysis process is green, efficient and pollution-free.
Description
Technical Field
The invention belongs to the field of biomass energy utilization, and particularly relates to a method for preparing furfural by co-pyrolysis.
Background
Furfural, also known as α -furfural, is an organic solvent with good selectivity, suitable dissolving capacity, and low toxicity, is an important raw material for synthetic resins, nylon, paints, and the like, and also an important raw material for synthesizing fine chemicals such as medicines, pesticides, preservatives, and the like, and has a high annual demand. Biomass raw materials such as agricultural and forestry wastes are important raw materials for preparing furfural. At present, the biomass raw materials are mainly used for preparing furfural industrially by a hydrolysis method, acid catalysts such as sulfuric acid and the like used in the method can remain in the hydrolysis liquid, the catalysts are difficult to recover, water pollution is easy to cause, and the problems become important factors restricting the development of the industry.
The biomass fast pyrolysis provides a new idea for preparing specific chemicals such as furfural and the like. By directionally regulating and controlling the pyrolysis process, the bio-oil rich in specific high value-added chemicals can be directly obtained. The preparation of furfural by biomass fast pyrolysis usually requires an acidic catalyst, and the catalytic pyrolysis technology is generally classified into two types, one is that the catalyst is used for pretreating raw materials by an impregnation method, and the catalyst comprises metal salts (such as ZnCl)2、MgCl2、Fe2(SO4)3) And inorganic acids (e.g. H)2SO4) Etc.; another type is the use of solid catalysts to control the pyrolysis process by in situ catalysis or by ex situ catalysisThe catalyst used comprises a sulfated metal oxide (e.g. SO)4 2-/TiO2、SO4 2-/ZrO2、SO4 2-/SnO2) Conventional zeolite molecular sieves and various metal-modified zeolite molecular sieves (e.g., HZSM-5, CuSO)4Modified HZSM-5), and the like.
Chinese patent application CN201310242527.0 discloses a method for producing furfural by using biomass raw materials pretreated by microwave pyrolysis of inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, or inorganic salt catalysts such as magnesium chloride, ferric chloride, and zinc chloride. The method is realized by the following steps: soaking the crushed biomass raw material for 10-30 minutes by using a catalyst aqueous solution with the mass fraction of 5-15%; and then performing microwave pyrolysis on the dried raw material for 5-20 minutes in an inert atmosphere, wherein the pyrolysis temperature is 150-280 ℃, and condensing pyrolysis gas to obtain a high-concentration furfural solution. The catalyst used in the invention has low price and mild reaction conditions, and agricultural and forestry wastes such as straw, corn stalk, bamboo powder and the like can be used as raw materials for preparing furfural.
Chinese patent application CN201210288559.X discloses a method for preparing 5-methylfurfural by catalyzing fructosyl biomass raw material to be pyrolyzed by using an acid catalyst. The acidic catalyst used in the invention is solid acid, liquid acid or a mixture of the solid acid and the liquid acid, and covers most common acidic catalysts, including liquid acids such as sulfuric acid, hydrochloric acid, boric acid, nitric acid and the like; silicon-aluminum oxide, SBA-15, zirconia, titanium oxide, carbon sulfonic acid, heteropoly acid and other solid acids and corresponding solid super acids.
The catalytic pyrolysis of biomass avoids the problem that a large amount of waste liquid is formed in the process of generating furfural products, but the currently used catalytic process still faces environmental pollution and is difficult to recycle by using liquid or solid catalysts; the catalyst is difficult to prepare and the cost is high. Therefore, it is necessary to develop a method for preparing furfural with low cost, environmental friendliness and no pollution.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a green furfural preparation method.
The method specifically comprises the following steps:
taking biomass rich in xylose units as a raw material for preparing furfural, and mixing and contacting the raw material with oxalic acid; and then carrying out co-pyrolysis reaction at 200-500 ℃ under an anaerobic condition, wherein the heating time is not more than 20 minutes, collecting pyrolysis gas, and condensing to obtain a furfural-rich liquid product.
Oxalic acid, an organic carboxylic acid with a crystalline structure, has mild acidity. It is widely existed in plants, and the industrial production method is mature, so the price is low. More importantly, the oxalic acid can be completely decomposed under the condition of heating to form CO and CO2And H2O, so selective production of furfural using oxalic acid instead of the existing conventional catalyst can be attempted.
The mechanism of the furfural preparation method provided by the invention is as follows: the biomass and oxalic acid are subjected to a CO-pyrolysis reaction under the heating condition, and the oxalic acid is decomposed into CO and CO2And H2And O promotes the xylose units in the biomass to be decomposed to form furfural with high selectivity.
The mixing contact is to mechanically mix the raw materials with oxalic acid, or to dip the raw materials in oxalic acid solution and then dry the raw materials.
When the raw material and oxalic acid are mechanically mixed, the mass ratio of the raw material to the oxalic acid is 1: 10-10: 1.
When the raw material is soaked in the oxalic acid solution and then dried, the ratio of the raw material to the oxalic acid solution is 1g:1 mL-1 g:1L, and the concentration of oxalic acid is 0.1 mol/L-2 mol/L.
The biomass raw material rich in xylose units comprises but is not limited to xylose, methyl xylose, xylobiose, xylan, corncob, corn straw, poplar and the like, and the particle size of the raw material is less than 0.50 mm.
The anaerobic condition is to maintain the reaction system under the inert anaerobic protective gas environment.
The pyrolysis reaction is to place the raw materials into a reactor constant-temperature area after the reactor is preheated to a set pyrolysis temperature; or the raw materials are put into a constant temperature area of the reactor at room temperature, and then the reactor is rapidly heated to the set pyrolysis temperature, wherein the heating rate is not lower than 100 ℃/s.
The invention has the beneficial effects that:
according to the invention, the biomass raw material rich in xylose units is mixed with oxalic acid to contact for co-pyrolysis, so as to prepare the liquid product rich in furfural. Oxalic acid is common and easy to obtain, can catalyze the pyrolysis of raw materials, converts xylose units in the raw materials into furfural with extremely high selectivity, and has high yield and good purity; while oxalic acid decomposes to CO in pyrolysis2CO and H2O, can not remain in solid phase, liquid phase or gas phase products, so that the pyrolysis process is green, efficient and pollution-free.
Detailed Description
The invention provides a method for preparing furfural by co-pyrolysis, which is further described by combining a specific embodiment. It should be understood that the following detailed description is illustrative of the invention only and is not intended to limit the scope of the invention.
The liquid product yield calculation method in the following examples is as follows:
Liquid product yield-mass of collected liquid product ÷ mass sum of starting material and oxalic acid.
In the following examples, the content of furfural was analyzed by a gas chromatography/mass spectrometer, and quantitative determination was performed by an external standard method, and the calculation method of furfural yield and selectivity was as follows:
the yield of furfural is divided by the mass of furfural and the mass of the raw material;
the selectivity of furfural is divided by the mass of furfural and the mass of organic liquid product (organic matter excluding water in the liquid product).
The percentages in the following examples are by mass unless otherwise specified.
The experimental procedures in the following examples are conventional unless otherwise specified.
Example 1
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 56.9%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 13.1% and the selectivity is 61.5% by calculation.
Example 2
Taking 100g of dried corn straws (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corn straws and oxalic acid, wherein the mass ratio of the corn straws to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 54.8%; the content of the furfural in the liquid product is analyzed by a gas chromatography/mass spectrometer, and the moisture content of the liquid product is measured, so that the yield of the furfural is 12.3 percent, and the selectivity is 57.1 percent.
Example 3
Taking 10g of dry commercial xylan (the proportion of xylose groups exceeds 90 percent) as a raw material, firstly, mechanically and uniformly mixing the xylan and oxalic acid, wherein the mass ratio of the xylan to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 56.5%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 15.9% and the selectivity is 68.4% by calculation.
Example 4
Taking 10g of dry xylose as a raw material, firstly, mechanically and uniformly mixing the xylose and oxalic acid, wherein the mass ratio of the xylose to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 56.3%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 18.2% and the selectivity is 71.1% by calculation.
Example 5
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 6; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 52.9%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 13.4% and the selectivity is 62.3% by calculation.
Example 6
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 8; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 54.4%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is calculated to be 13.3% and the selectivity is calculated to be 60.9%.
Example 7
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 10; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 54.6%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 13.9% and the selectivity is 63.1% by calculation.
Example 8
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 3; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 50.4%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 11.8% and the selectivity is 59.6% by calculation.
Example 9
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 47.7%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.4% and the selectivity is 46.9% by calculation.
Example 10
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 1; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 45.8%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 7.9% and the selectivity is 30.2% by calculation.
Example 11
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 5: 1; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 46.8%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 5.4% and the selectivity is 8.0% by calculation.
Example 12
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 10: 1; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 56.4%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is calculated to be 4.8% and the selectivity is calculated to be 6.7%.
Example 13
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 45.8%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.1% and the selectivity is 57.7% by calculation.
Example 14
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 10 minutes, and the yield of the obtained liquid product is 47.5%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 10.9% and the selectivity is 58.9% by calculation.
Example 15
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 10 minutes, and the yield of the obtained liquid product is 49.4%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.0% and the selectivity is 46.6% by calculation.
Example 16
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 43.9%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 11.4% and the selectivity is 52.6% by calculation.
Example 17
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 43.1%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 8.4% and the selectivity is 46.7% by calculation.
Example 18
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to 500 ℃ fast pyrolysis in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 45.1%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 8.9% and the selectivity is 53.6% by calculation.
Example 19
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 500 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 45.4%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 8.6% and the selectivity is 46.3% by calculation.
Example 20
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 3; then, the mixture is subjected to fast pyrolysis at 500 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 47.5%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.5% and the selectivity is 52.2% by calculation.
Example 21
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 350 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 51.8%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 11.4% and the selectivity is 59.9% by calculation.
Example 22
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 350 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 44.4%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 8.5% and the selectivity is 55.2% by calculation.
Example 23
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 3; then, the mixture is subjected to fast pyrolysis at 350 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 43.8%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 11.1% and the selectivity is 56.5% by calculation.
Example 24
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 300 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 49.6%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 10.2% and the selectivity is 57.5% by calculation.
Example 25
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 300 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 46.2%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.4% and the selectivity is 56.6% by calculation.
Example 26
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 3; then, the mixture is subjected to fast pyrolysis at 300 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 45.2%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 10.6% and the selectivity is 52.4% by calculation.
Example 27
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 4; then, the mixture is subjected to fast pyrolysis at 200 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 42.6%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is calculated to be 8.2% and the selectivity is calculated to be 50.8%.
Example 28
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 2; then, the mixture is subjected to fast pyrolysis at 200 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 41.0 percent; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 7.4% and the selectivity is 45.2% by calculation.
Example 29
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly, mechanically and uniformly mixing the corncobs and oxalic acid, wherein the mass ratio of the corncobs to the oxalic acid is 1: 3; then, the mixture is subjected to fast pyrolysis at 200 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 38.7%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is calculated to be 8.1 percent, and the selectivity is calculated to be 44.4 percent.
Example 30
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 1L of oxalic acid solution with the concentration of 2mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying for 12h at 40 ℃, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, the raw materials are subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 51.3%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 10.2% and the selectivity is 57.6% by calculation.
Example 31
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 1L of oxalic acid solution with the concentration of 2mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying for 12h at 40 ℃, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, fast pyrolyzing the raw materials at 350 ℃ in a nitrogen atmosphere, and heating for 10 minutes to obtain a liquid product with the yield of 45.6%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is calculated to be 9.0 percent, and the selectivity is calculated to be 54.5 percent.
Example 32
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 1L of oxalic acid solution with the concentration of 2mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying for 12h at 40 ℃, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, fast pyrolyzing the raw materials at 300 ℃ in a nitrogen atmosphere, heating for 5 minutes to obtain a liquid product with the yield of 43.9%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 8.3% and the selectivity is 49.2% by calculation.
Example 33
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 1L of oxalic acid solution with the concentration of 2mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying for 12h at 40 ℃, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, the raw materials are rapidly pyrolyzed at 500 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 43.5 percent; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 8.2% and the selectivity is 50.0% by calculation.
Example 34
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 2L of oxalic acid solution with the concentration of 1mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying at 40 ℃ for 12h, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, the raw materials are subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 52.2%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.8% and the selectivity is 56.3% by calculation.
Example 35
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 2L of oxalic acid solution with the concentration of 1mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying at 40 ℃ for 12h, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, fast pyrolyzing the raw materials at 350 ℃ in a nitrogen atmosphere, and heating for 10 minutes to obtain a liquid product with the yield of 41.6%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is calculated to be 8.8% and the selectivity is calculated to be 50.3%.
Example 36
Taking 100g of dried corncobs (with the particle size of 0.1-0.3 mm) as a raw material, firstly preparing 2L of oxalic acid solution with the concentration of 1mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying at 40 ℃ for 12h, and crushing the dried raw material (with the particle size of 0.1-0.3 mm); then, the raw materials are rapidly pyrolyzed at 300 ℃ in the nitrogen atmosphere, the heating time is 5 minutes, and the yield of the obtained liquid product is 46.2%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.7% and the selectivity is 52.5% by calculation.
Example 37
Taking 100g of dried corncobs (with the grain diameter of 0.1-0.3 mm) as a raw material, firstly preparing 4L of oxalic acid solution with the concentration of 0.5mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying for 12h at 40 ℃, and crushing the dried raw material (with the grain diameter of 0.1-0.3 mm); then, the raw materials are subjected to fast pyrolysis at 400 ℃ in the nitrogen atmosphere, the heating time is 15 minutes, and the yield of the obtained liquid product is 51.3%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 10.0% and the selectivity is 54.9% by calculation.
Example 38
Taking 100g of dried corncobs (with the grain diameter of 0.1-0.3 mm) as a raw material, firstly preparing 4L of oxalic acid solution with the concentration of 0.5mol/L, soaking the corncobs in the oxalic acid solution, stirring for 20min, carrying out ultrasonic treatment for 2h, drying for 12h at 40 ℃, and crushing the dried raw material (with the grain diameter of 0.1-0.3 mm); then, fast pyrolyzing the raw materials at 300 ℃ in a nitrogen atmosphere, and heating for 10 minutes to obtain a liquid product with the yield of 43.1%; the content of the furfural in the furfural is analyzed by a gas chromatography/mass spectrometer, the moisture content of the liquid product is measured, and the yield of the furfural is 9.2% and the selectivity is 50.6% by calculation.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. A method for preparing furfural through co-pyrolysis is characterized in that biomass rich in xylose units is used as a raw material for preparing furfural, the biomass rich in xylose units is corncobs, and the corncobs and oxalic acid are mechanically mixed in a mass ratio of 1: 10-1: 3; then carrying out co-pyrolysis reaction at 200-500 ℃ under an oxygen-free condition, wherein the heating time is not more than 20 minutes; and collecting pyrolysis gas, and condensing to obtain a liquid product rich in furfural.
2. The method for preparing furfural through co-pyrolysis as claimed in claim 1, wherein the oxygen-free condition is to maintain the reaction system under an inert oxygen-free protective gas environment.
3. The method for preparing furfural through co-pyrolysis according to claim 1, wherein the co-pyrolysis reaction is carried out by putting the raw materials into a constant temperature area of a reactor after the reactor is preheated to a set co-pyrolysis temperature.
4. The method for preparing furfural by co-pyrolysis according to claim 1, wherein the co-pyrolysis reaction is to rapidly heat the reactor to a set co-pyrolysis temperature after the raw materials are placed in a reactor constant-temperature area at room temperature, and the heating rate is not lower than 100 ℃/s.
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