Catalyst for preparing sorbitol from cellulose by one-step method and preparation method and application of catalyst
阅读说明：本技术 一种用于纤维素一步法制备山梨醇的催化剂及其制备方法和应用 (Catalyst for preparing sorbitol from cellulose by one-step method and preparation method and application of catalyst ) 是由 仇茉 张慧玲 刘龙新 张克强 于 2021-09-15 设计创作，主要内容包括：本发明属于催化剂技术领域,提供了一种用于纤维素一步法制备山梨醇的催化剂的制备方法,向阳离子表面活性剂的水溶液中依次加入非水溶性钌盐、偏钨酸铵/钼酸铵和水玻璃进行水热晶化,再进行碳化和还原,最后进行磺化处理。本发明利用杂原子钨或钼来改变钌基催化剂的活性,先通过水热晶化使杂原子与钌源结合,再通过还原使杂原子进入到钌晶体中使得钌的外层电子发生部分偏移,从而减弱了钌对氢气的吸附和活化能力,兼顾了水解与加氢的反应速率,实现了提升山梨醇选择性的目的。实施例的结果显示,采用本发明提供的制备方法制备的催化剂用于纤维素一步法制备山梨醇,山梨醇产率可达61.7％。(The invention belongs to the technical field of catalysts, and provides a preparation method of a catalyst for preparing sorbitol by a cellulose one-step method. According to the invention, the activity of the ruthenium-based catalyst is changed by using heteroatom tungsten or molybdenum, the heteroatom is combined with a ruthenium source through hydrothermal crystallization, and then the heteroatom enters a ruthenium crystal through reduction so that outer layer electrons of ruthenium partially deviate, thus the adsorption and activation capacities of ruthenium on hydrogen are weakened, the reaction rate of hydrolysis and hydrogenation is considered, and the purpose of improving the selectivity of sorbitol is realized. The results of the examples show that the catalyst prepared by the preparation method provided by the invention is used for preparing the sorbitol by a cellulose one-step method, and the yield of the sorbitol can reach 61.7%.)
1. A preparation method of a catalyst for preparing sorbitol by a cellulose one-step method comprises the following steps:
(1) adding water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate and water glass into an aqueous solution of a cationic surfactant in sequence, and carrying out hydrothermal crystallization to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt;
(2) carbonizing the MCM-41 molecular sieve containing the water-insoluble ruthenium salt obtained in the step (1) in an inert atmosphere to obtain a carbonized MCM-41 molecular sieve;
(3) at H2Reducing the carbonized MCM-41 molecular sieve obtained in the step (2) in an atmosphere to obtain a modified ruthenium-based catalyst;
(4) and (4) mixing the modified ruthenium-based catalyst obtained in the step (3) with a sulfuric acid aqueous solution, and performing sulfonation treatment to obtain the catalyst for preparing the sorbitol by the cellulose one-step method.
2. The method according to claim 1, wherein the ratio of the amounts of the water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate, cationic surfactant and water glass in step (1) is (0.01-0.05): (0.002-0.005): (0.1-0.15): 1.
3. the method according to claim 1 or 2, wherein the cationic surfactant in the step (1) comprises cetyltrimethylammonium bromide and/or cetyltrimethylammonium chloride.
4. The production method according to claim 1 or 2, wherein the water-insoluble ruthenium salt in the step (1) comprises ruthenium acetylacetonate.
5. The production method according to claim 1 or 2, wherein the modulus of the water glass in the step (1) is 3.2 to 3.5.
6. The preparation method according to claim 1, wherein the temperature of hydrothermal crystallization in the step (1) is 120-150 ℃, and the time of hydrothermal crystallization is 5-10 h.
7. The preparation method according to claim 1, wherein the carbonization temperature in the step (2) is 500-600 ℃ and the carbonization time is 1-3 h.
8. The preparation method according to claim 1, wherein the temperature of the reduction in the step (3) is 600-700 ℃ and the time of the reduction is 2-6 h.
9. The catalyst for preparing the sorbitol from the cellulose by the one-step method, which is prepared by the preparation method of any one of claims 1 to 8.
10. The use of the catalyst for cellulose one-step preparation of sorbitol according to claim 9 in catalyzing cellulose one-step preparation of sorbitol, comprising:
at H2Under the atmosphere, cellulose, a catalyst for preparing the sorbitol by the cellulose one-step method and a sulfuric acid aqueous solution are mixed and subjected to one-step reaction to obtain the sorbitol.
Technical Field
The invention relates to the technical field of catalysts, in particular to a catalyst for preparing sorbitol by a cellulose one-step method and a preparation method and application thereof.
Background
Sorbitol is an important fine chemical, is listed as one of TOP12 renewable resource platform compounds by the United states department of energy, and is widely applied to the fields of food, medicine, light industry, chemical industry and the like. At present, edible starch and glucose are mainly used as raw materials in China, and sorbitol is prepared in a kettle type hydrogenation mode, so that food resources are occupied in a certain proportion; in addition, as the preparation process of sorbitol in China mostly adopts a nickel-based catalyst, in the reaction process, heavy metals such as Ni and the like can be corroded by acid to a certain extent and then run off into the target product sorbitol, so that the purity and the quality of the sorbitol are directly influenced, and the application of the sorbitol in the fields of food and medicines is greatly limited. Therefore, the preparation of high-quality sorbitol meeting the medical and food standards by using cellulose conversion not only can avoid the problem of food competition with people, but also can bring greater economic value, thereby having important research significance.
In recent years, the one-step (hydrolysis/hydrogenation) preparation of sorbitol from cellulose by using a metal ruthenium-based bifunctional catalyst which is not easy to lose has attracted much attention. The combination of in-situ hydrolysis and hydrogenation in the same reactor can quickly remove unstable cellooligosaccharide and saccharide intermediates, thereby reducing the occurrence of side reactions such as glucose isomerization and polycondensation. In addition, active sites of hydrolysis and hydrogenation in the ruthenium-based bifunctional catalyst are closer in spatial distance, and hydrolysis product glucose can quickly contact with the hydrogenation active sites for hydrogenation, so that the accumulation of glucose in a system is reduced, and the forward progress of cellulose hydrolysis reaction is promoted, thereby improving the conversion rate of cellulose and the yield of sorbitol. Most of the ideas consider that the hydrolysis of cellulose to generate glucose is a rapid control step of the whole reaction, side reactions such as sorbitol hydrogenolysis and the like are main factors influencing the selectivity of sorbitol, the side reactions such as sorbitol hydrogenolysis and the like are often caused and accelerated by taking a metal ruthenium group as a catalyst under a higher temperature (180-220 ℃), and the temperature is more favorable for the reaction of preparing glucose by hydrolysis of cellulose in an aqueous phase, so that a catalyst capable of balancing contradictions between different reaction stages of hydrolysis and hydrogenation is required to be provided to improve the selectivity of sorbitol.
Disclosure of Invention
The invention aims to provide a catalyst for preparing sorbitol by a cellulose one-step method, and a preparation method and application thereof.
In order to achieve the above purpose, the invention provides the following technical scheme:
the invention provides a preparation method of a catalyst for preparing sorbitol by a cellulose one-step method, which comprises the following steps:
(1) adding water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate and water glass into an aqueous solution of a cationic surfactant in sequence, and carrying out hydrothermal crystallization to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt;
(2) carbonizing the MCM-41 molecular sieve containing the water-insoluble ruthenium salt obtained in the step (1) in an inert atmosphere to obtain a carbonized MCM-41 molecular sieve;
(3) at H2Reducing the carbonized MCM-41 molecular sieve obtained in the step (2) in an atmosphere to obtain a modified ruthenium-based catalyst;
(4) and (4) mixing the modified ruthenium-based catalyst obtained in the step (3) with a sulfuric acid aqueous solution, and performing sulfonation treatment to obtain the catalyst for preparing the sorbitol by the cellulose one-step method.
Preferably, the ratio of the amounts of the water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate, the cationic surfactant and the water glass in the step (1) is (0.01-0.05): (0.002-0.005): (0.1-0.15): 1.
preferably, the cationic surfactant in step (1) comprises cetyltrimethylammonium bromide and/or cetyltrimethylammonium chloride.
Preferably, the water-insoluble ruthenium salt in the step (1) includes ruthenium acetylacetonate.
Preferably, the modulus of the water glass in the step (1) is 3.2-3.5.
Preferably, the temperature of hydrothermal crystallization in the step (1) is 120-150 ℃, and the time of hydrothermal crystallization is 5-10 h.
Preferably, the carbonization temperature in the step (2) is 500-600 ℃, and the carbonization time is 1-3 h.
Preferably, the reduction temperature in the step (3) is 600-700 ℃, and the reduction time is 2-6 h.
The invention provides the catalyst for preparing the sorbitol by the cellulose one-step method, which is prepared by the preparation method in the technical scheme.
The invention also provides an application of the catalyst for preparing the sorbitol by the cellulose one-step method in catalyzing the cellulose to prepare the sorbitol by the cellulose one-step method, which comprises the following steps:
at H2Under the atmosphere, cellulose, a catalyst for preparing the sorbitol by the cellulose one-step method and a sulfuric acid aqueous solution are mixed and subjected to one-step reaction to obtain the sorbitol.
The invention provides a preparation method of a catalyst for preparing sorbitol by a cellulose one-step method, which comprises the following steps: adding water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate and water glass into an aqueous solution of a cationic surfactant in sequence, and carrying out hydrothermal crystallization to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt; carbonizing the MCM-41 molecular sieve containing the water-insoluble ruthenium salt in an inert atmosphere to obtain a carbonized MCM-41 molecular sieve; at H2Reducing the carbonized MCM-41 molecular sieve under the atmosphere to obtain a modified ruthenium-based catalyst; and mixing the modified ruthenium-based catalyst with a sulfuric acid aqueous solution, and performing sulfonation treatment to obtain the catalyst for preparing the sorbitol by the cellulose one-step method. The invention utilizes heteroatom tungsten or molybdenum to change the activity of ruthenium-based catalyst, firstly combines the heteroatom with ruthenium source through hydrothermal crystallization, and then leads the heteroatom to enter ruthenium crystal through reductionTherefore, partial deviation of outer layer electrons of ruthenium occurs, partial transfer of the outer layer electrons of ruthenium weakens the adsorption and activation capacity of ruthenium on hydrogen, the adsorption dissociation capacity of hydrogen on the surface of the ruthenium is reduced, the reaction rate of hydrolysis and hydrogenation is considered, the purpose of improving the selectivity of sorbitol is achieved, and the yield of sorbitol is improved. The results of the examples show that the catalyst prepared by the preparation method provided by the invention is used for preparing the sorbitol by a cellulose one-step method, and the yield of the sorbitol can reach 61.7%.
Drawings
FIG. 1 is a transmission electron micrograph of a catalyst prepared in example 1 of the present invention;
FIG. 2 is a transmission electron micrograph of a catalyst prepared in example 2 of the present invention;
fig. 3 is a transmission electron micrograph of the catalyst prepared in comparative example 1.
Detailed Description
The invention provides a preparation method of a catalyst for preparing sorbitol by a cellulose one-step method, which comprises the following steps:
(1) adding water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate and water glass into an aqueous solution of a cationic surfactant in sequence, and carrying out hydrothermal crystallization to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt;
(2) carbonizing the MCM-41 molecular sieve containing the water-insoluble ruthenium salt obtained in the step (1) in an inert atmosphere to obtain a carbonized MCM-41 molecular sieve;
(3) at H2Reducing the carbonized MCM-41 molecular sieve obtained in the step (2) in an atmosphere to obtain a modified ruthenium-based catalyst;
(4) and (4) mixing the modified ruthenium-based catalyst obtained in the step (3) with a sulfuric acid aqueous solution, and performing sulfonation treatment to obtain the catalyst for preparing the sorbitol by the cellulose one-step method.
The method comprises the steps of sequentially adding water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate and water glass into an aqueous solution of a cationic surfactant, and carrying out hydrothermal crystallization to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt.
In the present invention, the cationic surfactant preferably comprises cetyltrimethylammonium bromide and/or cetyltrimethylammonium chloride, more preferably cetyltrimethylammonium bromide; the ratio of the amount of the cationic surfactant to the amount of the water in the aqueous solution of the cationic surfactant is preferably (0.1 to 0.15): (40 to 60), more preferably (0.12 to 0.15): (50 to 60). According to the invention, water-insoluble ruthenium salt is coated in micelles formed by the cationic surfactant by using the aqueous solution of the cationic surfactant, so that the water-insoluble ruthenium salt is uniformly dispersed, and uniformly dispersed ruthenium nanoparticles are obtained in the subsequent carbonization process; meanwhile, cations on the outer layer of the cationic surfactant micelle can be combined with anions generated after hydrolysis of ammonium metatungstate/ammonium molybdate, so that tungstate ions or molybdate ions are uniformly dispersed on the outer layer of the micelle.
In the present invention, the water-insoluble ruthenium salt preferably includes ruthenium acetylacetonate. The invention takes water-insoluble ruthenium salt as a ruthenium source and can be uniformly dispersed in micelles formed by the cationic surfactant. The source of the water-insoluble ruthenium salt is not particularly limited in the present invention, and commercially available products well known to those skilled in the art may be used.
In the invention, the modulus of the water glass is preferably 3.2-3.5, and more preferably 3.4-3.5. The invention takes water glass as a silicon source, takes a cationic surfactant as a template agent, and forms a stable MCM-41 molecular sieve through hydrothermal crystallization, and if sodium silicate is taken as a silicon source, the MCM-41 molecular sieve can not be obtained. The modulus of the water glass is preferably controlled within the range, and the excessive sodium ions in the water glass can influence the crystallization process of MCM-41 and is not beneficial to the formation of the MCM-41 molecular sieve.
In the present invention, the ratio of the amounts of the water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate, cationic surfactant and water glass is preferably (0.01 to 0.05): (0.002-0.005): (0.1-0.15): 1, more preferably (0.02 to 0.05): (0.003-0.005): (0.12-0.15): 1. according to the invention, the ratio of the quantity of the water-insoluble ruthenium salt, the ammonium metatungstate/ammonium molybdate, the cationic surfactant and the water glass is preferably controlled within the range, so that the structural composition and the catalytic effect of the catalyst are ensured.
According to the present invention, it is preferable to add the water-insoluble ruthenium salt, ammonium metatungstate/ammonium molybdate and water glass to the aqueous solution of the cationic surfactant in this order under stirring. In the invention, the stirring temperature is preferably 40-60 ℃, and more preferably 45-55 ℃; the stirring speed is preferably 100-1000 r/min, and more preferably 300-800 r/min. In the invention, the stirring time after adding the water-insoluble ruthenium salt into the water solution of the cationic surfactant is preferably 3-5 h; the stirring time after adding the ammonium metatungstate/ammonium molybdate is preferably 1-2 h; the stirring time after adding the water glass is preferably 1-2 h. Adding water-insoluble ruthenium salt into a water solution of a cationic surfactant to uniformly disperse the water-insoluble ruthenium salt into micelles formed by the cationic surfactant, adding ammonium metatungstate/ammonium molybdate, hydrolyzing to generate tungstate ions or molybdate ions, combining the tungstate ions or molybdate ions with cations on the outer layer of the cationic surfactant micelles, adding water glass, taking the cationic surfactant as a template agent, and performing hydrothermal crystallization to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt.
According to the invention, the pH value of the solution is preferably adjusted and stirred for a period of time after the stirring after the water glass is added, and then the hydrothermal crystallization is carried out. According to the invention, the pH value of the solution is preferably adjusted to 10-12, and the reagent for adjusting the pH value of the solution is preferably hydrochloric acid. In the invention, the stirring time is preferably 5-8 h, and more preferably 6-8 h; the stirring speed is preferably 100-1000 r/min, and more preferably 200-800 r/min.
In the invention, the temperature of the hydrothermal crystallization is preferably 120-150 ℃, and more preferably 130-140 ℃; the time for the hydrothermal crystallization is preferably 5-10 hours, and more preferably 6-8 hours. The invention preferably controls the temperature and time of the hydrothermal crystallization within the range, which is favorable for obtaining the MCM-41 molecular sieve with stable structure. In the invention, the device for hydrothermal crystallization is preferably a hydrothermal crystallization kettle.
After the hydrothermal crystallization is finished, the product after the hydrothermal crystallization is preferably subjected to suction filtration and drying to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt. The invention preferably adopts a solid-liquid separation mode of suction filtration, which is beneficial to the retention of the cationic surfactant in the MCM-41 molecular sieve, and further is converted into a nitrogen-doped carbon material after carbonization and dispersed in the pore channel of the MCM-41 molecular sieve.
After the MCM-41 molecular sieve containing the water-insoluble ruthenium salt is obtained, the method carries out carbonization on the MCM-41 molecular sieve containing the water-insoluble ruthenium salt under inert atmosphere to obtain the carbonized MCM-41 molecular sieve. According to the method, water-insoluble ruthenium salt is decomposed into ruthenium nano particles through carbonization, tungstate ions or molybdate ions generated after hydrolysis of ammonium metatungstate/ammonium molybdate are decomposed into tungsten oxide or molybdenum oxide, and the generated tungsten oxide or molybdenum oxide can be combined with the inner wall of a silicon oxide pore channel in the MCM-41 molecular sieve, so that the effect of uniform dispersion is achieved.
In the invention, the carbonization temperature is preferably 500-600 ℃, and more preferably 550-600 ℃; the carbonization time is preferably 1-3 h, and more preferably 1-2 h. In the present invention, it is preferable to control the temperature and time of the carbonization within the above ranges, which is advantageous for complete decomposition of the water-insoluble ruthenium salt and tungstate ions or molybdate ions. In the present invention, the carbonization apparatus is preferably a tube furnace. In the present invention, the inert atmosphere is preferably a nitrogen atmosphere.
After obtaining the carbonized MCM-41 molecular sieve, the method is carried out in H2And reducing the carbonized MCM-41 molecular sieve under the atmosphere to obtain the modified ruthenium-based catalyst. The invention is achieved by2Tungsten oxide or molybdenum oxide is reduced to elemental tungsten or elemental molybdenum in the atmosphere and then combined with ruthenium to form a eutectic compound, so that the electronic structure of ruthenium deviates towards tungsten or molybdenum, the adsorption and activation capacity of the catalyst on hydrogen is weakened, the adsorption dissociation capacity of hydrogen on the surface of the catalyst is reduced, the reaction rate of hydrolysis and hydrogenation is taken into consideration, and the aim of improving the selectivity of sorbitol is fulfilled. In the present invention, said H2The preferred space velocity of (a) is 10-50 min-1More preferably 20 to 40min-1。
In the invention, the reduction temperature is preferably 600-700 ℃, and more preferably 630-680 ℃; the reduction time is preferably 2-6 h, and more preferably 3-5 h. The invention preferably controls the reduction temperature in the range, thereby not only realizing the reduction of tungsten oxide or molybdenum oxide, but also not wasting energy; the elemental ruthenium generated after carbonization can activate hydrogen, so that the reduction of tungsten oxide or molybdenum oxide can be realized by controlling the reduction temperature within the range.
After the reduction is completed, the invention preferably washes the reduced product to obtain the modified ruthenium-based catalyst. The operation mode of the washing is not particularly limited in the present invention, and a washing technical scheme well known to those skilled in the art may be adopted. In the present invention, the detergent used for the washing is preferably deionized water. According to the invention, water-soluble impurity ions are preferably removed by washing, so that the influence of impurity ions such as sodium ions and the like remained in the pore channels on the activity of the catalyst is avoided.
After the modified ruthenium-based catalyst is obtained, the modified ruthenium-based catalyst is mixed with a sulfuric acid aqueous solution for sulfonation treatment, and the catalyst for preparing the sorbitol by the cellulose one-step method is obtained. According to the invention, sulfonic groups are grafted on the nitrogen-doped carbon material formed after the cationic surfactant is carbonized through sulfonation treatment, so that a hydrolysis acid center is provided for the catalyst, and meanwhile, as nitrogen is a basic site, sulfonic functional groups are easy to graft and the grafting is firm, so that the hydrolysis activity of the catalyst is improved.
In the present invention, the mass concentration of the sulfuric acid aqueous solution is preferably 1 to 10%, more preferably 2 to 8%. The method for preparing the aqueous solution of sulfuric acid is not particularly limited in the present invention, and a method for preparing a solution known to those skilled in the art may be used. In the invention, the sulfonation treatment time is preferably 3-5 h, and more preferably 3 h.
According to the invention, the activity of the ruthenium-based catalyst is changed by using the heteroatom tungsten or molybdenum, the heteroatom is combined with the ruthenium source through hydrothermal crystallization, and then the heteroatom enters the ruthenium crystal through reduction, so that partial deviation of outer-layer electrons of ruthenium occurs, and partial transfer of the outer-layer electrons of ruthenium weakens the adsorption and activation capacities of ruthenium on hydrogen, reduces the adsorption dissociation capacity of hydrogen on the surface of the ruthenium, further considers the reaction rate of hydrolysis and hydrogenation, realizes the purpose of improving the selectivity of sorbitol, and further improves the yield of sorbitol.
The invention provides the catalyst for preparing the sorbitol by the cellulose one-step method, which is prepared by the preparation method in the technical scheme.
The catalyst for preparing the sorbitol by the cellulose one-step method provided by the invention gives consideration to the reaction rate of hydrolysis and hydrogenation, realizes the purpose of improving the selectivity of the sorbitol, and further improves the yield of the sorbitol.
The invention also provides an application of the catalyst for preparing the sorbitol by the cellulose one-step method in catalyzing the cellulose to prepare the sorbitol by the cellulose one-step method, which comprises the following steps:
at H2Under the atmosphere, cellulose, a catalyst for preparing the sorbitol by the cellulose one-step method and a sulfuric acid aqueous solution are mixed and subjected to one-step reaction to obtain the sorbitol.
In the present invention, the cellulose is preferably ball milled cellulose; the mass concentration of the sulfuric acid aqueous solution is preferably 0.01-0.1%, and more preferably 0.05-0.08%; the mass ratio of the cellulose to the mass of the catalyst for preparing the sorbitol by the cellulose one-step method to the volume of the sulfuric acid aqueous solution is preferably (1-5) g: 1 g: (10-40) mL, more preferably (2-4) g: 1 g: (20-30) mL.
In the present invention, said H2The pressure intensity of the pressure is preferably 1-4 MPa, and more preferably 2-3 MPa; the reaction temperature of the one-step reaction is preferably 120-200 ℃, and more preferably 130-180 ℃; the reaction time of the one-step reaction is preferably 0.5-5 h, and more preferably 1-4 h. In the present invention, the one-step reaction is preferably carried out in a reaction tank.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
(1) Adding ruthenium acetylacetonate into an aqueous solution of hexadecyl trimethyl ammonium bromide at the temperature of 50 ℃, stirring for 3 hours, adding ammonium metatungstate, stirring for 1 hour, adding water glass with the modulus of 3.2, continuously stirring for 1 hour, dropwise adding hydrochloric acid to adjust the pH value of the solution to 10, and continuously stirring for 5 hours; then transferring the solution to a hydrothermal crystallization kettle, carrying out hydrothermal crystallization for 5h at 120 ℃, carrying out suction filtration and drying to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt; wherein the mass ratio of the ruthenium acetylacetonate, the ammonium metatungstate, the hexadecyl trimethyl ammonium bromide and the water glass is 0.025: 0.003: 0.12: 1; the mass ratio of cetyltrimethylammonium bromide to water in the aqueous solution of cetyltrimethylammonium bromide was 0.12: 50; the stirring speed is 500 r/min;
(2) putting the MCM-41 molecular sieve containing the water-insoluble ruthenium salt obtained in the step (1) into a tubular furnace, and heating to 500 ℃ in a nitrogen atmosphere for carbonization for 1h to obtain a carbonized MCM-41 molecular sieve;
(3) switching nitrogen in a tube furnace to H2，H2Space velocity of 20min-1Reducing the carbonized MCM-41 molecular sieve obtained in the step (2) at 600 ℃ for 2h, cooling to room temperature, purging with nitrogen for 2h, washing with deionized water, and drying to obtain a modified ruthenium-based catalyst;
(4) and (4) mixing the modified ruthenium-based catalyst obtained in the step (3) with a 2 wt% sulfuric acid aqueous solution, performing sulfonation treatment for 3 hours, washing with water and drying to obtain the catalyst for preparing the sorbitol by the cellulose one-step method, wherein the number of the catalyst is CAT-1.
FIG. 1 is a transmission electron micrograph of the catalyst prepared in this example. As can be seen from FIG. 1, the catalyst prepared in this example has mesoporous channels similar to MCM-41, and the metal active components are uniformly distributed.
Example 2
(1) Adding ruthenium acetylacetonate into the aqueous solution of hexadecyl trimethyl ammonium bromide at the temperature of 50 ℃, and stirring for 3 hours; adding ammonium molybdate, stirring for 1h, adding water glass with a modulus of 3.2, continuously stirring for 1h, dropwise adding hydrochloric acid to adjust the pH value of the solution to 10, and continuously stirring for 5 h; then transferring the solution to a hydrothermal crystallization kettle, carrying out hydrothermal crystallization for 5h at 120 ℃, carrying out suction filtration and drying to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt; wherein the mass ratio of the ruthenium acetylacetonate, the ammonium molybdate, the hexadecyl trimethyl ammonium bromide and the water glass is 0.025: 0.003: 0.12: 1; the mass ratio of cetyltrimethylammonium bromide to water in the aqueous solution of cetyltrimethylammonium bromide was 0.12: 50; the stirring speed is 600 r/min;
(2) putting the MCM-41 molecular sieve containing the water-insoluble ruthenium salt obtained in the step (1) into a tubular furnace, and heating to 500 ℃ in a nitrogen atmosphere for carbonization for 1h to obtain a carbonized MCM-41 molecular sieve;
(3) switching nitrogen in a tube furnace to H2，H2Space velocity of 20min-1Reducing the carbonized MCM-41 molecular sieve obtained in the step (2) at 600 ℃ for 2h, cooling to room temperature, purging with nitrogen for 2h, washing with deionized water, and drying to obtain a modified ruthenium-based catalyst;
(4) and (4) mixing the modified ruthenium-based catalyst obtained in the step (3) with a 2 wt% sulfuric acid aqueous solution, performing sulfonation treatment for 3 hours, washing with water and drying to obtain the catalyst for preparing the sorbitol by the cellulose one-step method, wherein the catalyst is numbered as CAT-2.
FIG. 2 is a transmission electron micrograph of the catalyst prepared in this example. It can be seen from fig. 2 that the catalyst prepared in this example has mesoporous channels similar to MCM-41, and the metal active components are uniformly distributed.
Example 3
(1) Adding ruthenium acetylacetonate into the aqueous solution of hexadecyl trimethyl ammonium bromide at the temperature of 50 ℃, and stirring for 3 hours; adding ammonium metatungstate, stirring for 1h, adding water glass with a modulus of 3.2, continuously stirring for 1h, dropwise adding hydrochloric acid to adjust the pH value of the solution to 10, and continuously stirring for 5 h; then transferring the solution to a hydrothermal crystallization kettle, carrying out hydrothermal crystallization for 5h at 120 ℃, carrying out suction filtration and drying to obtain the MCM-41 molecular sieve containing the water-insoluble ruthenium salt; wherein the mass ratio of ruthenium acetylacetonate, ammonium metatungstate, hexadecyl trimethyl ammonium bromide and water glass is 0.01: 0.002: 0.1: 1; the mass ratio of cetyltrimethylammonium bromide to water in the aqueous solution of cetyltrimethylammonium bromide was 0.1: 60, adding a solvent to the mixture; the stirring speed is 500 r/min;
(2) putting the MCM-41 molecular sieve containing the water-insoluble ruthenium salt obtained in the step (1) into a tubular furnace, and heating to 500 ℃ in a nitrogen atmosphere for carbonization for 1h to obtain a carbonized MCM-41 molecular sieve;
(3) switching nitrogen in a tube furnace to H2，H2Space velocity of 20min-1Reducing the carbonized MCM-41 molecular sieve obtained in the step (2) at 600 ℃ for 2h, cooling to room temperature, purging with nitrogen for 2h, washing with deionized water, and drying to obtain a modified ruthenium-based catalyst;
(4) and (4) mixing the modified ruthenium-based catalyst obtained in the step (3) with a 2 wt% sulfuric acid aqueous solution, performing sulfonation treatment for 3 hours, washing with water and drying to obtain the catalyst for preparing the sorbitol by the cellulose one-step method, wherein the number of the catalyst is CAT-3.
Example 4
The difference from example 1 was that cetyltrimethylammonium bromide in step (1) was replaced with cetyltrimethylammonium chloride, and the resulting catalyst was numbered CAT-4.
Example 5
The difference from example 2 was that cetyltrimethylammonium bromide in step (1) was replaced with cetyltrimethylammonium chloride, and the resulting catalyst was numbered CAT-5.
Comparative example 1
The difference from example 1 was that in step (1), water glass having a modulus of 2.0 was added, and the catalyst obtained was named CAT-6.
Fig. 3 is a transmission electron micrograph of the catalyst prepared in this comparative example. Fig. 3 shows that the catalyst prepared in comparative example 1 has no clear ordered mesoporous channels, which indicates that the modulus of water glass has an important influence on the generation of ordered mesoporous materials.
Comparative example 2
The difference from example 1 was that 600 ℃ in step (3) was changed to 550 ℃ and the catalyst obtained was numbered CAT-7.
Comparative example 3
The difference from example 1 was that the nitrogen atmosphere in step (2) was changed to an air atmosphere, and the catalyst obtained was numbered CAT-8.
Comparative example 4
The difference from example 1 is that ammonium metatungstate was not added in step (1), and the catalyst obtained was CAT-9.
Application example 1
4g of ball-milled cellulose and 1g of the catalyst prepared in examples 1 to 5 and comparative examples 1 to 4 were placed in a reaction vessel containing 20mL of a 0.05 wt% aqueous solution of sulfuric acid, and charged with 3MPa of H2After sealing, the reaction was carried out in one step at 150 ℃ and after 2 hours the reaction was complete and the yield of sorbitol was determined by liquid chromatography and the results are shown in Table 1.
TABLE 1 sorbitol yield for catalysts prepared in examples 1-5 and comparative examples 1-4
The embodiments show that the catalyst for preparing sorbitol by a cellulose one-step method provided by the invention achieves the purpose of improving the selectivity of sorbitol and improves the yield of sorbitol, and the catalyst prepared by the preparation method provided by the invention is used for preparing sorbitol by a cellulose one-step method, and the yield of sorbitol can reach 61.7%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.