A sulfonic acid group functionalized molecular sieve solid acid and a preparation method and application thereof

Abstract

The application discloses a sulfonic acid group functionalized molecular sieve solid acid and a preparation method and application thereof, and belongs to the technical field of solid acid catalyst preparation and application. 4+ The sulfonic acid group functionalized molecular sieve solid acid catalyst is prepared by synthesizing Sn Doped molecular sieve KIT-6 is subjected to a silanization reaction on the surface to graft a mercapto group, and is further oxidized into a sulfonic acid group to obtain the sulfonic acid group functionalized molecular sieve solid acid catalyst which is used for catalyzing xylose and yellow ginger residues (residues after yellow ginger saponin is extracted from yellow ginger) to prepare furfural. The solid acid catalyst prepared from the sulfonic acid group functionalized molecular sieve has high acid density, stable structure and excellent catalytic performance, so that the biomass yellow ginger residues can be catalytically converted to prepare furfural at a high yield.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid acid catalyst preparation, and particularly relates to a preparation method of a sulfonic acid group functionalized molecular sieve solid acid and application of the solid acid in preparation of furfural from biomass turmeric residue. BACKGROUND

[0002] Turmeric is a perennial herbaceous plant, and the rhizome contains 2.5-9.0% of turmeric saponin. The turmeric saponin is a starting material for synthesizing steroid hormone drugs. A large amount of waste residue is generated after the turmeric saponin is extracted from the turmeric by a microbial method. The waste residue is randomly stacked to cause environmental pollution and other problems. The main component of the turmeric residue is lignocellulose. The amorphous hemicellulose in the lignocellulose can be hydrolyzed under the action of an acid catalyst to generate monosaccharides such as xylose by breaking glycosidic bonds, and then the monosaccharides are dehydrated to generate furfural, so that the turmeric residue can be efficiently utilized.

[0003] The acid catalyst is used to catalyze the model compound to dehydrate xylose to prepare furfural. Since the product furfural has a lively chemical property, it is easy to form soluble oligomers and insoluble humus by polymerization between the furfural and the reaction intermediates or itself, so that the yield of the furfural is reduced. Further, the acid catalyst is applied to hydrolysis and dehydration of polysaccharides in the biomass turmeric residue to convert and prepare furan products. Since the lignocellulose is a macromolecular polysaccharide and has a dense network structure to effectively hinder the hydrolysis of the polysaccharide, the yield of the furan product is low, the conversion and utilization rate of the raw material is low, and the waste acid liquid is difficult to handle. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a sulfonic acid group functionalized molecular sieve solid acid, a preparation method and application thereof. The solid acid catalyst prepared from the sulfonic acid group functionalized molecular sieve has high acid density, stable structure and excellent catalytic performance, so that the biomass turmeric residue is catalytically converted to prepare furfural at a high yield.

[0005] The present application is realized by the following technical solutions:

[0006] A preparation method of a sulfonic acid group functionalized molecular sieve solid acid, comprising,

[0007] S1, polyether P123 is dissolved in a dilute hydrochloric acid solution, then n-butanol is added, and stirring is performed at room temperature, then tetraethyl silicate and a metal salt are added, and stirring is continuously performed, then hydrothermal reaction is performed, and then filtration, washing and drying are performed, and then calcination is performed to remove a template agent, so as to obtain a molecular sieve KIT-6 doped with metal ions;

[0008] S2, the metal ion doped molecular sieve KIT-6 is added into toluene, then (3-mercaptopropyl) trimethoxysilane is added for silanization reaction, after the reaction solution is washed, filtered and dried, hydrogen peroxide is added for reaction, and then the reaction solution is washed, filtered and dried to obtain the sulfonic acid group functionalized molecular sieve solid acid.

[0009] Preferably, the mass ratio of the polyether P123 to the dilute hydrochloric acid solution is 5.0g:200.0mL, the concentration of the dilute hydrochloric acid solution is 0.5mol / L, the mass ratio of the polyether P123 to n-butanol is 1:1, the mass ratio of the tetraethyl orthosilicate to n-butanol is 2:1, the mass fraction of the hydrogen peroxide is 30%, and the addition amount ratio of the hydrogen peroxide to toluene is 40.0mL:20mL.

[0010] Preferably, the metal salt includes zirconium oxychloride, isopropyl titanate and tin tetrachloride, and the molar ratio of Si element / metal element in the tetraethyl orthosilicate to the metal salt is 10:1-30:1.

[0011] Preferably, the stirring reaction time in S1 is 24h, the hydrothermal reaction condition is 24h of hydrothermal reaction at 100℃, the drying temperature is 80℃, the calcination condition is that the template agent is removed by heating to 550℃ at a heating rate of 5℃ / min and keeping for 5h;

[0012] The silanization reaction condition in S2 is refluxing at 130℃ for 24h, and the oxidation reaction time is 24h; in S2, the specific process of washing, filtering and drying the reaction solution is that the reaction solution is washed several times with ultrapure water, acetone and ethanol, then filtered, and then dried at 80℃ for 12h.

[0013] Preferably, the addition amount ratio of toluene to (3-mercaptopropyl) trimethoxysilane is 20mL:2.0g, and the addition amount ratio of the metal ion doped molecular sieve KIT-6 to toluene is 1g:20mL.

[0014] A sulfonic acid group functionalized molecular sieve solid acid is prepared by the above preparation method.

[0015] The sulfonic acid group functionalized molecular sieve solid acid is used in the preparation of furfural from xylose and ginseng residue, the xylose or ginseng residue is added into the inner liner of a high-pressure reaction kettle together with the sulfonic acid group functionalized molecular sieve solid acid and a reaction solvent according to a mass ratio of 2:1-1:1, and then reacted at 160-180℃ for 60min to prepare furfural.

[0016] Preferably, the ginseng residue is pretreated with formic acid solution before being added into the sulfonic acid group functionalized molecular sieve solid acid.

[0017] Preferably, the reaction solvent is a mixed solvent of γ-valerolactone and water.

[0018] Preferably, the yield of furfural and 5-hydroxymethylfurfural obtained in the reaction of preparing furfural from the turmeric residue reaches 57.4% and 14.6%, respectively.

[0019] Compared with the prior art, the present application has the following beneficial technical effects:

[0020] The present application provides a preparation method of sulfonic acid functionalized molecular sieve solid acid and its application in the preparation of furfural from biomass turmeric residue. The sulfonic acid functionalized molecular sieve solid acid is prepared by synthesizing metal ion doped molecular sieve KIT-6 through sol-gel method, then grafting sulfonic acid group by reacting with silanization reagent and oxidizing it. The prepared molecular sieve solid acid is used to catalyze the preparation of furfural from xylose and biomass turmeric residue. The molecular sieve KIT-6 has the advantages of high thermal stability, large specific surface area, large and adjustable pore size, and is widely used. The metal ion is doped into the molecular sieve framework in the form of tetrahedral coordination and serves as the Lewis acid site for isomerization of monosaccharide. The hydroxyl group on the surface of the molecular sieve reacts with the silanization reagent to graft the sulfonic acid group, which serves as the dehydration reaction site. Therefore, the molecular sieve solid acid can be applied to catalyze the reaction of preparing furfural from xylose and biomass turmeric residue, and promote the preparation of furfural from biomass residue.

[0021] Further, the metal ion is zirconium oxychloride, isopropyl titanate and tin tetrachloride, wherein Sn 4+ can combine with or replace part of Si 4+ in the hydroxyl group of [SiO4] tetrahedron to form Sn-O-Si bond and be doped into the molecular sieve KIT-6 to generate Lewis acid site.

[0022] Further, the yield of furfural prepared by the sulfonic acid functionalized molecular sieve solid acid catalyst from xylose can reach 82.6%.

[0023] Further, after the turmeric residue is pretreated with formic acid, the yield of furfural and 5-hydroxymethylfurfural (HMF) prepared from the sugar solution extracted from the turmeric residue reaches 57.4% and 14.6%, respectively.

[0024] Further, the pretreatment of the turmeric residue with formic acid can destroy the dense structure of lignocellulose and improve the yield of furfural and HMF. Therefore, the sulfonic acid functionalized molecular sieve solid acid catalytic reaction system disclosed in the present application realizes the goal of green and efficient catalytic conversion of turmeric residue to furfural. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 XRD spectra of different component sulfonic acid functionalized molecular sieve solid acid catalysts.

[0026] Figure 2 TEM images of the sulfonic group functionalized molecular sieve solid acid catalyst of the present application, Fig. (a) is the Sn 4+ TEM images of the oxide formed by doping in the molecular sieve, Fig. (b) is the distribution of Si element in the sulfonic group functionalized molecular sieve solid acid, Fig. (c) is the distribution of Sn element in the sulfonic group functionalized molecular sieve solid acid, Fig. (d) is the distribution of S element in the sulfonic group functionalized molecular sieve solid acid, Fig. (e) is the element content diagram of C, O, Si, Sn, S;

[0027] Figure 3 Py-FTIR images of the sulfonic group functionalized molecular sieve solid acid catalyst of different components. DETAILED DESCRIPTION

[0028] The present application will be further described in detail below with specific examples, which are an explanation of the present application rather than a limitation.

[0029] The following steps:

[0030] S1: polyether P123 is added to a dilute hydrochloric acid solution, stirred to dissolve, then n-butanol is added, stirred at room temperature, then tetraethyl silicate (TEOS) and metal salt are added, and stirring is continued for 24 h. The solution is transferred to an autoclave, and hydrothermal treatment is carried out at 100℃ for 24 h. The reaction solution is washed and filtered, dried at 80℃, and then calcined in a muffle furnace to remove the template (n-butanol, polyether P123), to obtain a metal ion doped molecular sieve KIT-6. Research has found that the solid acid has The acid sites are the main catalytic active sites for the conversion of biomass into furfural, and the Lewis acid sites are beneficial to the isomerization of xylose, thereby enhancing the catalytic activity.

[0031] S2: the metal ion doped molecular sieve is added to toluene, then (3-mercaptopropyl)trimethoxysilane (MPTMS) is added, refluxed at 130℃ for 24 h, the reaction solution is washed, filtered and dried, then hydrogen peroxide (H2O2, 30%) is added, and reacted for 24 h. The reaction solution is washed, filtered and dried to obtain the molecular sieve solid acid.

[0032] Preferably, the amount of polyether P123 used in S1 is 5.0 g, the amount of dilute hydrochloric acid used is 200.0 mL of 0.5 mol / L HCl, the amount of n-butanol used is 5.0 g, and the amount of TEOS used is 10.0 g.

[0033] Preferably, the type of metal salt added in S1 is zirconium oxychloride, isopropyl titanate, and tin tetrachloride, and the amount added is calculated according to the Si / metal molar ratio of 20 to be 0.39, 0.42, and 0.34 g, respectively.

[0034] Preferably, the amount of SnCl4 added in S1 is calculated according to the Si / Sn molar ratio of 10, 20, 30, and the mass of SnCl4 added is 0.84, 0.42 and 0.28 g, respectively.

[0035] Preferably, in S1, the temperature is raised to 550℃ at a rate of 5℃ / min in a muffle furnace, and the calcination is maintained for 5h to remove the template agent.

[0036] Preferably, in S2, the amount of toluene solvent is 20mL, and 2.0g of MPTMS is added dropwise. The reaction solution is washed with ultrapure water, acetone and ethanol several times, and then filtered under suction, and dried at 80℃ for 12h.

[0037] Preferably, in S2, 40.0mL of H2O2 is added dropwise, and the reaction is carried out at room temperature for 24h. The reactants are washed with water and ethanol and filtered under suction, and then dried at 80℃ for 12h.

[0038] The application also discloses a sulfonic acid group functionalized molecular sieve solid acid prepared by the above method.

[0039] The application also discloses an application of the above sulfonic acid group functionalized molecular sieve solid acid.

[0040] Preferably, the application refers to an application in the catalytic conversion of model compounds xylose and biomass turmeric residues to prepare furfural, and the specific steps are as follows:

[0041] The raw material is added in a 10mL polytetrafluoroethylene liner in an amount of 2:1 to 1:1 of the mass ratio of the raw material to the catalyst, 5mL of solvent is added, the sealed reaction kettle is placed in a heating furnace, heated to 160-180℃, and reacted for 60min to prepare the product furfural.

[0042] The turmeric residue is a residue after extracting saponin from turmeric, and the component content of the turmeric residue is determined by the NREL method, wherein the cellulose content is 21.8wt.%, the hemicellulose content is 10.6wt.%, and the lignin content is 22.5wt.%.

[0043] The following detailed description is a description of the examples, and is intended to provide further detailed description of the application. Unless otherwise specified, all technical terms used in the application have the same meaning as understood by those skilled in the art to which the application belongs. The terms used in the application are only for the purpose of describing the specific embodiments, and are not intended to limit the example embodiments according to the application.

[0044] Example 1

[0045] 5.0 g of polyether P123 was added to 200.0 mL of 0.5 mol / L HCl solution and stirred for 30 min to form a transparent solution. 5.0 g of n-butanol was slowly added and stirred at room temperature for 1 h, and then 10.0 g of TEOS was added dropwise. According to the molar ratio of Si / Zr of 20, 0.39 g of zirconium oxychloride was added to the above solution and stirred at room temperature for 24 h. The viscous liquid was transferred to an inner-lining sealed and placed in an oven for hydrothermal reaction at 100 °C for 24 h. The reaction liquid was filtered and washed with ultrapure water and ethanol. The filtrate was dried at 80 °C for 12 h, and then heated to 550 °C at a rate of 5 °C / min in a muffle furnace, and calcined for 5 h to remove the template to obtain Sn 4+ doped KIT-6-Zr(20);

[0046] 1.0 g of KIT-6-Zr(20) was added to a flask, and 20.0 mL of toluene was added dropwise. After stirring for 30 min, 2.0 g of (3-mercaptopropyl)trimethoxysilane (MPTMS) was added, and refluxed at 130 °C for 24 h. The reaction liquid was suction filtered and washed with ultrapure water, acetone and ethanol several times, and dried at 80 °C for 12 h. After drying, the sample was added to a flask, and 40.0 mL of H2O2 was added dropwise and reacted at room temperature for 24 h. The reaction was suction filtered and washed with water and ethanol, and dried at 80 °C for 12 h to obtain a sulfonic acid functionalized molecular sieve solid acid KIT-6-Zr(20)-SO3H.

[0047] The prepared molecular sieve solid KIT-6-Zr(20)-SO3H was applied to the reaction of catalyzing xylose to prepare furfural. 0.1 g of xylose, 0.05 g of sulfonic acid functionalized molecular sieve solid acid, and 5 mL of GVL solvent were weighed into a 10 mL polytetrafluoroethylene inner lining sealed reaction kettle, which was placed in a heating furnace at a rotation speed of 200 r / min and a temperature of 170 °C, and reacted for 60 min. The product content in the reaction liquid was detected by HPLC, and the furfural yield was determined to be 60.1%.

[0048] Example 2

[0049] The sulfonic acid functionalized molecular sieve solid acid was prepared in the same manner as in Example 1, except that according to the molar ratio of Si / Ti of 20:1, 0.34 g of isopropyl titanate was added to the above solution and stirred at room temperature for 24 h to obtain a sulfonic acid functionalized molecular sieve solid acid KIT-6-Ti(20)-SO3H.

[0050] The prepared catalyst was applied to the reaction of catalyzing xylose to prepare furfural in the same manner as in Example 1, and the furfural yield was determined to be 63.7%.

[0051] Example 3

[0052] The sulfonic acid functionalized molecular sieve solid acid was prepared in the same manner as in example 1 except that 0.42 g of tin tetrachloride was added to the above solution according to a Si / Sn molar ratio of 20:1 and stirred for 24 h at room temperature to obtain the sulfonic acid functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H.

[0053] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose in the same manner as in example 1 to determine a furfural yield of 76.5%.

[0054] Example 4

[0055] The sulfonic acid functionalized molecular sieve solid acid was prepared in the same manner as in example 3 except that 0.84 g of tin tetrachloride was added to the above solution according to a Si / Sn molar ratio of 10:1 and stirred for 24 h at room temperature to obtain the sulfonic acid functionalized molecular sieve solid acid KIT-6-Sn(10)-SO3H.

[0056] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose in the same manner as in example 1 to determine a furfural yield of 69.2%.

[0057] Example 5

[0058] The sulfonic acid functionalized molecular sieve solid acid was prepared in the same manner as in example 3 except that 0.28 g of tin tetrachloride was added to the above solution according to a Si / Sn molar ratio of 30:1 and stirred for 24 h at room temperature to obtain the sulfonic acid functionalized molecular sieve solid acid KIT-6-Sn(30)-SO3H.

[0059] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose in the same manner as in example 1 to determine a furfural yield of 73.4%.

[0060] Example 6

[0061] The sulfonic acid functionalized molecular sieve solid acid was prepared in the same manner as in example 3 except that tin tetrachloride was not added in the preparation of the catalyst to obtain the sulfonic acid functionalized molecular sieve solid acid KIT-6-SO3H.

[0062] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose in the same manner as in example 1 to determine a furfural yield of 59.9%.

[0063] Example 7

[0064] The sulfonic acid functionalized molecular sieve solid acid was prepared in the same manner as in example 3 except that Sn 4+ The doped KIT-6-Sn(20) was not grafted with sulfonic acid groups to obtain the molecular sieve solid acid KIT-6-Sn(20).

[0065] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose according to the reaction mode of Example 1, and the yield of furfural was determined to be 12.8%.

[0066] Example 8

[0067] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared according to the mode of Example 3.

[0068] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose according to the reaction mode of Example 1, except that the reaction temperature was 160°C, and the yield of furfural was determined to be 79.7%.

[0069] Example 9

[0070] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared according to the mode of Example 3.

[0071] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose according to the reaction mode of Example 1, except that the amount of catalyst was 0.075 g and the reaction temperature was 160°C, and the yield of furfural was determined to be 82.6%.

[0072] Example 10

[0073] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared according to the mode of Example 3.

[0074] The prepared catalyst was applied to the reaction of catalyzing the preparation of furfural from xylose according to the reaction mode of Example 1, except that the amount of catalyst was 0.075 g and the reaction temperature was 160°C, and the yield of furfural was determined to be 82.6%.

[0075] Example 11

[0076] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared according to the mode of Example 3.

[0077] Furfural was prepared by using formic acid solution to pretreat the residue of yellow ginger and then adding solid acid to catalyze the residue of yellow ginger. 0.2 g of residue of yellow ginger, 10 mL of 90% (V / V) formic acid solution, 140 °C for 60 min, the reaction liquid was filtered, the filtrate was removed by rotary evaporation to obtain a sticky material, then 3 mL of GVL and 2 mL of H2O were added, 0.05 g of catalyst, 180 °C for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 52.1% and 11.8%, respectively.

[0078] Example 12

[0079] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared in the manner of Example 3.

[0080] Furfural was prepared by using formic acid solution to pretreat the residue of yellow ginger and then adding solid acid to catalyze the residue of yellow ginger. 0.2 g of residue of yellow ginger, 10 mL of 90% (V / V) formic acid solution, 140 °C for 60 min, the reaction liquid was filtered, the filtrate was removed by rotary evaporation to obtain a sticky material, then 3 mL of GVL and 2 mL of H2O were added, 0.05 g of catalyst, 180 °C for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 52.1% and 11.8%, respectively.

[0081] Example 13

[0082] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared in the manner of Example 3.

[0083] Furfural was prepared by using formic acid solution to pretreat the residue of yellow ginger and then adding solid acid to catalyze the residue of yellow ginger. 0.2 g of residue of yellow ginger, 10 mL of 90% (V / V) formic acid solution, 140 °C for 60 min, the reaction liquid was filtered, the filtrate was removed by rotary evaporation to obtain a sticky material, then 3 mL of GVL and 2 mL of H2O were added, 0.05 g of catalyst, 180 °C for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 52.1% and 11.8%, respectively.

[0084] Example 14

[0085] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared in the manner of Example 3.

[0086] Furfural was prepared by using formic acid solution to pretreat the residue of yellow ginger and then adding solid acid to catalyze the residue of yellow ginger. 0.2 g of residue of yellow ginger, 10 mL of 90% (V / V) formic acid solution, 140 °C for 60 min, the reaction liquid was filtered, the filtrate was removed by rotary evaporation to remove water formic acid and water to obtain a sticky material, then 3 mL of GVL and 2 mL of H2O, 0.05 g of catalyst, 200 °C for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 50.2% and 10.4%, respectively.

[0087] Example 15

[0088] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared in the manner of Example 3.

[0089] Furfural was prepared by using formic acid solution to pretreat the residue of yellow ginger and then adding solid acid to catalyze the residue of yellow ginger. 0.2 g of residue of yellow ginger, 10 mL of 90% (V / V) formic acid solution, 140 °C for 60 min, the reaction liquid was filtered, the filtrate was removed by rotary evaporation to remove water formic acid and water to obtain a sticky material, then 3 mL of GVL and 2 mL of H2O, 0.05 g of catalyst, 200 °C for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 50.2% and 10.4%, respectively.

[0090] Example 16

[0091] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared in the manner of Example 3.

[0092] Furfural was prepared by using formic acid solution to pretreat the residue of yellow ginger and then adding solid acid to catalyze the residue of yellow ginger. 0.2 g of residue of yellow ginger, 10 mL of 90% (V / V) formic acid solution, 140 °C for 60 min, the reaction liquid was filtered, the filtrate was removed by rotary evaporation to remove water formic acid and water to obtain a sticky material, then 3 mL of GVL and 2 mL of H2O, 0.05 g of catalyst, 200 °C for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 50.2% and 10.4%, respectively.

[0093] Example 17

[0094] The sulfonic acid group functionalized molecular sieve solid acid KIT-6-Sn(20)-SO3H was prepared in the manner of Example 3.

[0095] The ginseng residue was pretreated with formic acid solution and then catalyzed by solid acid to prepare furfural. 0.2 g of ginseng residue, 10 mL of 90% (V / V) formic acid solution, 140℃ for 60 min, the reaction liquid was filtered, the filtrate was concentrated by rotary evaporation to remove formic acid and water to obtain a viscous material, then 3 mL of GVL and 2 mL of H2O, 0.125 g of catalyst, 190℃ for 60 min. The product content in the reaction liquid was detected by HPLC, and the yield of furfural and 5-hydroxymethylfurfural (HMF) was 53.6% and 9.8%, respectively.

[0096] The application discloses a preparation method of a sulfonic acid group functionalized molecular sieve solid acid catalyst KIT-6-Sn(20)-SO3H. The catalyst is applied to catalyze xylose to prepare furfural, and the yield of furfural can reach 82.6%. Further, the catalyst is applied to catalyze ginseng residue to prepare furfural in a one-step method, and the yield of furfural and 5-hydroxymethylfurfural is low. After the ginseng residue is pretreated with 90% (V / V) formic acid solution, the ginseng residue is catalyzed by solid acid in a two-step method to prepare furfural, and the yield of furfural and 5-hydroxymethylfurfural reaches 57.4% and 14.6%, respectively. The yield of furfural prepared from ginseng residue can be obviously improved after pretreatment with formic acid, thereby being beneficial to realizing the goal of green and efficient catalytic conversion of ginseng residue to prepare furfural, and effectively improving the conversion and utilization value of the waste biomass residue.

[0097] Test result analysis

[0098] Figure 1 The XRD spectrum of the sulfonic acid group functionalized molecular sieve solid acid catalyst with different components. The relatively wide diffraction peak of the molecular sieve KIT-6 between 15-30° of the 2θ angle corresponds to the amorphous structure of the molecular sieve. The peak type of KIT-6-SO3H does not change compared with that of KIT-6, indicating that the sulfonic acid group grafting does not change the framework structure of the molecular sieve KIT-6. According to the Si / Sn molar ratio of 10, 20 and 30, Sn 4+ is doped into the framework of the molecular sieve, and the characteristic peaks of SnO2 at 26.6°, 33.8° and 51.7° of the 2θ angle are attributed to the (110), (101) and (211) crystal faces of SnO2. When the Si / Sn molar ratio increases from 10 to 30, the amount of Sn 4+ doped into the molecular sieve gradually decreases, resulting in the weakening of the characteristic peak intensity of SnO2. The characteristic peak of SnO2 does not change after the Sn-doped molecular sieve is grafted with the sulfonic acid group, indicating that the sulfonic acid group grafting has no obvious influence on the framework structure of the Sn-doped molecular sieve. 4+

[0099] Figure 2 The TEM image of the sulfonic acid group functionalized molecular sieve solid acid catalyst. The TEM image of the molecular sieve KIT-6 shows that the molecular sieve KIT-6 is a kind of spherical molecular sieve with a diameter of about 200 nm. The TEM image of the KIT-6-SO3H shows that the molecular sieve KIT-6 is a kind of spherical molecular sieve with a diameter of about 200 nm, and the surface of the molecular sieve KIT-6 is covered with a large number of sulfonic acid groups. Figure 2 ​In a, the darker part is Sn 4+ Oxides formed by incorporation in the molecular sieve. In the figure and The lattice spacing of (110), (101) and (211) planes of SnO2 tetragonal phase, which is consistent with the analysis of the XRD pattern. Due to the doping of Sn 4+ and the grafting of sulfonic acid groups, part of the pore structure is blocked and difficult to distinguish from the figure. In the EDS element mapping of the catalyst Figure 2 b~2e, the elements C, O, Si, Sn, S in the catalyst are evenly distributed on the surface of the catalyst, and the corresponding element content is 30.75, 46.20, 22.47, 0.30, 0.28 (at. %), respectively, thereby proving that Sn 4+ and sulfonic acid groups are introduced into the molecular sieve structure.

[0100] Figure 3 Py-FTIR figure of the sulfonic acid functionalized molecular sieve solid acid catalyst. When the basic pyridine molecules are adsorbed on the Lewis or acid sites on the surface of the sample, different characteristic absorption peaks are corresponded on the infrared spectrum. The intensity of the absorption peak is positively correlated with the acid density, and the acid density on the surface of the sample is calculated by the peak area, and the results are summarized in Table 1. When the basic pyridine molecules are adsorbed on the Lewis or acid sites on the surface of the sample, different characteristic absorption peaks are corresponded on the infrared spectrum. Since the surface of the molecular sieve KIT-6 only contains weakly acidic Si-OH groups, the contents of L acid and B acid are low. After the grafting of sulfonic acid groups on the surface of the molecular sieve KIT-6-SO3H, the contents of B acid and L acid are increased, and the increase of the content of L acid may be explained as the induction of the oxygen atom in the -SO3H group to the silicon atom, which makes the silicon atom exhibit L acid sites, thereby causing the increase of the content of L acid. In the Sn 4+ doped KIT-6-Sn(20), the Sn 4+ species incorporated into the silicon-oxygen tetrahedron to form a tetrahedral Sn, which leads to the increase of L acid sites, but the content of B acid is low. After the grafting of sulfonic acid groups on KIT-6-Sn(20), KIT-6-Sn(20)-SO3H is obtained, the content of B acid is increased and the total acid content reaches 345.1 μmol / g. The acidity titration analysis of the solid acid catalyst shows that the total acid content of the molecular sieve KIT-6 is 0.22 mmol / g, and the amount of sulfonic acid groups is increased after the grafting of sulfonic acid groups on KIT-6-SO3H. In KIT-6-Sn(20), the Sn 4+ doped in the molecular sieve has little effect on the acid content, and needs to be modified to increase the acid content. After the grafting of sulfonic acid groups on KIT-6-Sn(20)-SO3H, the total acid content is increased to 0.96 mmol / g, indicating that the grafted sulfonic acid groups have a significant effect on the total acid content.

[0101] Table 1 Acid content of molecular sieve solid acid

[0102]

[0103] a Acid site content was calculated by pyridine infrared test at 100°C; b Acid content was determined by acidity titration.

[0104] It is to be understood that the application can be carried out by other specific arrangements, which do not depart from the spirit or essential characteristics of the application. Thus, the above described embodiments are merely illustrative, and not restrictive, of the application, as many modifications and other embodiments thereof will become apparent to those skilled in the art upon reviewing the above description. Accordingly, the full scope of the application should be determined only by reference to the appended claims, rather than by reference to the foregoing description, and all modifications and alterations that come within the scope of the application are intended to be protected.

[0105] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this description, the singular forms "a", "an" and "the" include plural references, unless the context clearly dictates otherwise. The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0106] The above description is only the preferred embodiment of the application, not any form of limitation to the application; anyone with ordinary skill in the art can easily implement the application according to the drawings and the above description; however, anyone with ordinary skill in the art can make some changes, modifications and equivalent changes to the above disclosed technical contents without departing from the scope of the technical solutions of the application; meanwhile, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the application are still within the protection scope of the technical solutions of the application.

Claims

1. The application of a sulfonic acid-functionalized molecular sieve solid acid in the conversion of turmeric residue to furfural, characterized in that, include: Furfural was prepared by reacting the residue of turmeric with the sulfonic acid-functionalized molecular sieve solid acid and reaction solvent. The turmeric residue is first pretreated with formic acid solution and then sulfonic acid-functionalized molecular sieve solid acid is added. The preparation method of the sulfonic acid-functionalized molecular sieve solid acid includes: S1, after dissolving polyether P123 in dilute hydrochloric acid solution, n-butanol was added and stirred at room temperature, tetraethyl silicate and metal salt were added, and the reaction was continued by stirring. After hydrothermal reaction, the mixture was filtered, washed, dried, and calcined to obtain metal ion-doped molecular sieve KIT-6. S2, metal ion-doped molecular sieve KIT-6 is added to toluene, and then (3-mercaptopropyl)trimethoxysilane is added to carry out a silanization reaction. After washing, filtering and drying the reaction solution, hydrogen peroxide is added to react, and after washing, filtering and drying, sulfonic acid functionalized molecular sieve solid acid is obtained. The metal salt includes zirconium oxychloride, isopropyl titanate, or tin tetrachloride, wherein the molar ratio of tetraethyl silicate to Si in the metal salt is 10:1 to 30:

1. The ratio of toluene to (3-mercaptopropyl)trimethoxysilane added is 20 mL: 2.0 g.

2. The application of the sulfonic acid-functionalized molecular sieve solid acid according to claim 1 in the reaction of converting turmeric residue into furfural, characterized in that, The ratio of polyether P123 to dilute hydrochloric acid solution is 5.0 g: 200.0 mL, wherein the concentration of dilute hydrochloric acid solution is 0.5 mol / L; the mass ratio of polyether P123 to n-butanol is 1:1; the mass ratio of tetraethyl silicate to n-butanol is 2:1; the mass fraction of hydrogen peroxide is 30%, and the addition ratio of hydrogen peroxide to toluene is 40.0 mL: 20 mL.

3. The application of the sulfonic acid-functionalized molecular sieve solid acid according to claim 1 in the reaction of converting turmeric residue into furfural, characterized in that, The stirring reaction time in S1 is 24h, the hydrothermal reaction conditions are hydrothermal reaction at 100°C for 24h, the drying temperature is 80°C, and the calcination conditions are heating to 550°C at a heating rate of 5°C / min and calcining for 5h to remove the template agent. The conditions for the silanization reaction in S2 are: reflux at 130 °C for 24 h; the reaction time after adding hydrogen peroxide is 24 h; the specific process of washing, filtering and drying the reaction solution in S2 is as follows: the reaction solution is washed several times with ultrapure water, acetone and ethanol, filtered, and then dried at 80 °C for 12 h.

4. The application of the sulfonic acid-functionalized molecular sieve solid acid according to claim 1 in the reaction of converting turmeric residue into furfural, characterized in that, Furfural was prepared by adding the residue of turmeric, the sulfonic acid functionalized molecular sieve solid acid, and the reaction solvent into the lining of a high-pressure reactor at a mass ratio of 2:1 to 1:1 and reacting at 160 to 180 °C for 60 min.

5. The application of the sulfonic acid-functionalized molecular sieve solid acid according to claim 1 in the reaction of converting turmeric residue into furfural, characterized in that, The reaction solvent is a mixed solvent composed of γ-valerolactone and water.

6. The application of the sulfonic acid-functionalized molecular sieve solid acid according to claim 1 in the reaction of converting turmeric residue into furfural, characterized in that, The sulfonic acid-functionalized molecular sieve solid acid catalyst was used to catalyze the preparation of furfural from turmeric residue, and the yields of furfural and 5-hydroxymethylfurfural reached 57.4% and 14.6%, respectively.

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