Palladium-molybdenum bimetallic catalyst and preparation method, preparation equipment and application thereof
阅读说明：本技术 一种钯钼双金属催化剂及其制备方法、制备设备和用途 (Palladium-molybdenum bimetallic catalyst and preparation method, preparation equipment and application thereof ) 是由 阎智锋 冯宇 宋云彩 李跃斌 侯文生 史晟 于 2021-09-09 设计创作，主要内容包括：本发明公开了一种钯钼双金属催化剂及其制备方法、制备设备和用途,本发明通过依次制备钠型丝光沸石及氢型丝光沸石,并通过离子交换法得到钯钼双金属催化剂,制得的钯钼双金属催化剂的载体为丝光沸石,活性组分为钯和钼。在水热条件和氮气气氛下,所述钯钼双金属催化剂可直接催化纤维素源得到较高收率的5-羟甲基糠醛。本发明还公开了钯钼双金属催化剂的制备设备,包括：反应皿移动模块、加料搅拌模块、过滤洗涤模块、马弗炉、反应皿,所述设备可在计算机控制下,将反应皿按照特定的流程进行添加溶液、添加固态试剂、搅拌、过滤、洗涤、干燥和焙烧等操作。(The invention discloses a palladium-molybdenum bimetallic catalyst, a preparation method, preparation equipment and application thereof. Under hydrothermal conditions and nitrogen atmosphere, the palladium-molybdenum bimetallic catalyst can directly catalyze a cellulose source to obtain the 5-hydroxymethylfurfural with high yield. The invention also discloses a preparation device of the palladium-molybdenum bimetallic catalyst, which comprises the following components: the device comprises a reaction vessel moving module, a charging and stirring module, a filtering and washing module, a muffle furnace and a reaction vessel, wherein the reaction vessel can be subjected to operations of adding solution, adding solid reagents, stirring, filtering, washing, drying, roasting and the like according to a specific flow under the control of a computer.)
1. The preparation method of the palladium-molybdenum bimetallic catalyst is characterized by comprising the following steps of:
(1) NaAlO is added2The first alkali liquor and the deionized water are mixed according to the molar ratio of 1: (0.5-10): (50-1000) and mixing according to the proportion of SiO under stirring2With NaAlO2In a molar ratio of 1: (10-40) adding SiO2Crystallizing, filtering, washing, drying and roasting after crystallization is finished to prepare the sodium mordenite;
wherein the crystallization temperature is 100-;
(2) the sodium mordenite, a template agent, a second alkali solution, an alcohol solution and deionized water are mixed according to a molar ratio of 1: (0.1-50): (1-100): (1-700): (200-2000), filtering and washing the product after the alkalization treatment with deionized water for many times until the pH value of the filtrate is neutral, and then drying and roasting to prepare the hydrogen-type mordenite;
wherein the alkalization treatment temperature is 10-200 ℃, the alkalization treatment time is 10-48h, the drying temperature is 50-100 ℃, the drying time is 1-24h, the roasting temperature is 400-;
(3) mixing a palladium source and a molybdenum source according to a molar ratio of palladium to molybdenum of 1: (1-10) preparing a palladium-molybdenum mixed solution, adding the hydrogen-type mordenite into the palladium-molybdenum mixed solution, carrying out an ion exchange reaction under a stirring condition, and then filtering, washing, drying and roasting to obtain a palladium-molybdenum bimetallic catalyst;
wherein the ion exchange reaction temperature is 10-100 ℃, the reaction time is 5-48h, the drying temperature is 50-100 ℃, the drying time is 1-24h, the roasting temperature is 400-.
2. The method of claim 1, wherein the first and second lyes are at least one of sodium hydroxide solution, potassium hydroxide solution, and ammonia.
3. The method for preparing a palladium-molybdenum bimetallic catalyst as in claim 1 or 2, wherein the first alkali solution is 2mol/L sodium hydroxide solution, and the second alkali solution is 20-50 wt% ammonia water.
4. The method of claim 1, wherein the templating agent is cetyltrimethylammonium bromide templating agent.
5. The method for preparing a palladium-molybdenum bimetallic catalyst as in claim 1, wherein in the step (2), the alcohol solution is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol and decanol.
6. The method for preparing a palladium-molybdenum bimetallic catalyst according to claim 1, wherein in the step (3), the palladium source is at least one of palladium nitrate, palladium acetate, chloropalladic acid, palladium chloride and palladium sulfate, and the molybdenum source is at least one of ammonium molybdate and sodium molybdate.
7. The application of the palladium-molybdenum bimetallic catalyst prepared by the preparation method according to claim 1 in one-step preparation of 5-hydroxymethylfurfural by directly catalyzing and hydrolyzing a cellulose source is characterized in that: and (2) mixing the palladium-molybdenum bimetallic catalyst, a cellulose source and deionized water according to a mass ratio of 1: (4-200): (100-1000), performing nitrogen replacement for many times, heating for catalytic reaction, and filtering to obtain a 5-hydroxymethylfurfural solution; wherein the catalytic reaction temperature is 80-400 ℃, the catalytic reaction pressure is 1-10 MPa, and the catalytic reaction time is 1-5 h.
8. The use of the palladium-molybdenum bimetallic catalyst according to claim 7 in the direct catalytic hydrolysis of cellulose sources to produce 5-hydroxymethylfurfural in one step, wherein the cellulose sources can be one or more of cellulose raw materials including corn stover, poplar, hemp stover and beech, and glucose polymers including microcrystalline cellulose and cellobiose.
9. An apparatus for preparing a palladium-molybdenum bimetallic catalyst, comprising:
the reaction vessel moving module is used for moving the reaction vessel to different experimental stations and comprises an installation mainboard, a left-right moving module, a front-back guide cylinder and a gas claw for clamping the reaction vessel, wherein the installation mainboard is provided with the left-right moving module, the front-back guide cylinder is installed on a sliding part of the left-right moving module through a cylinder installation plate, and the gas claw is installed on the sliding part of the front-back guide cylinder through a gas claw installation plate;
the feeding and stirring module comprises a temperature control platform, a feeding air cylinder, a stirring lifting air cylinder, a stirrer motor and a charging box, wherein the temperature control platform, the feeding air cylinder and the charging box are all installed on the installation mainboard, the reaction vessel is arranged in a placing groove on the temperature control platform, the stirring lifting air cylinder is installed on the telescopic end of the feeding air cylinder through a feeding air cylinder connecting plate, a stirrer guide part is installed on the telescopic end of the stirring lifting air cylinder, the stirrer motor is installed on the stirrer guide part, the output end of the stirrer motor penetrates through the charging box and is connected with the stirrer, and the charging box is provided with a feeding motor and a feeding wheel;
the filtering and washing module comprises a liquid adding cylinder, the liquid adding cylinder is installed on an installation mainboard, a liquid adding cylinder connecting plate is installed at the telescopic end of the liquid adding cylinder, a filter lifting cylinder is installed at the upper end of the liquid adding cylinder connecting plate, a liquid adding cover is installed at the front end of the liquid adding cylinder, a filter installing plate is installed at the output end of the filter lifting cylinder, a through hole for a filter connecting pipe to pass through is formed in the center of the liquid adding cover, one end of the filter connecting pipe is connected with a peristaltic pump through a liquid path pipe, the other end of the filter connecting pipe is connected with a filter, a liquid path hole for installing a 5-channel liquid adding pipe is formed in the liquid adding cover, one end of the 5-channel liquid adding pipe passes through the liquid path hole of the liquid adding cover, the other end of the 5-channel liquid adding pipe is connected with the peristaltic pump through the liquid path pipe, the peristaltic pump is respectively connected with a liquid storage bottle and a waste liquid bottle, and the peristaltic pump respectively conveys liquid of the 5-channel liquid adding pipes to a reaction vessel, the peristaltic pump discharges the reagent in the reaction vessel to a waste liquid bottle through the filter;
the muffle furnace is arranged on the mounting main board, the height of the bottom in the muffle furnace is flush with a placing groove for placing a reaction vessel on the temperature control platform, and the front part of the muffle furnace is flush with the temperature control platform after the door of the muffle furnace is opened so as to avoid collision;
control module, including motor controller, solenoid valve controller, motion control ware and temperature controller, it passes through motor controller control to remove the movable mould group, cylinder, liquid feeding cylinder, filter are raised to front and back direction cylinder, gas claw, reinforced cylinder, stirring and are raised the cylinder and pass through trachea connection electromagnetism valves, and the solenoid valve is controlled through solenoid valve controller, reinforced motor, agitator motor, peristaltic pump, muffle furnace gate are controlled through motion control ware, muffle furnace, temperature control platform temperature are controlled through temperature controller.
10. The apparatus according to claim 9, wherein the liquid feeding cover is a disc shape matched with the reaction vessel in size, the liquid feeding cylinder can drive the 5-channel liquid feeding pipe and the filter to move up and down, the reaction vessel can be covered when the liquid feeding cover moves down, the filter lifting cylinder can drive the filter to move up and down, and the reaction vessel can be prevented from moving and colliding when the telescopic end of the liquid feeding cylinder and the filter lifting cylinder moves to the highest position.
Technical Field
The invention belongs to the technical field of solid catalysts, and particularly relates to a palladium-molybdenum bimetallic catalyst for catalyzing direct hydrolysis of a cellulose source to prepare 5-hydroxymethylfurfural, and a preparation method and preparation equipment thereof.
Background
The current resource crisis and environmental pollution problems have become global problems affecting countries throughout the world. Biomass, as the only renewable carbon source, is expected to be energy-utilized to replace fossil energy. Cellulose is the most abundant biomass resource, has the simplest structure composition, can be recycled, is easy to biodegrade, and has low price. Therefore, it is of great practical significance to treat cellulose by chemical methods or fermentation and then convert the cellulose into high value-added chemicals or fuels.
The 5-hydroxymethylfurfural is a platform compound with high added value, which can be prepared by dehydrating monosaccharide under an acidic condition, and the derivative of the compound can be used as a chemical raw material of various fine chemicals and novel high polymer materials. At present, the main means for preparing 5-hydroxymethylfurfural from cellulose is homogeneous catalysis of ionic liquid catalyst, liquid acid, metal ions and the like or heterogeneous catalysis of organic solvent and solid acid catalyst, and the better catalytic effect is shown, while the conversion efficiency in aqueous solution is relatively poor. However, the use of ionic liquids, liquid acids, metal ions and organic solvents is not only costly, but also causes environmental problems such as corrosion of equipment and secondary pollution, which severely restricts the industrial application thereof. Therefore, the key to solving the problem of 5-hydroxymethylfurfural production by cellulosic biomass is to find efficient green solvents and catalysts.
It is generally believed that the hydrolysis of cellulose to 5-hydroxymethylfurfural undergoes three main processes, namely hydrolysis of cellulose to glucose, isomerization of glucose to fructose, and dehydration of fructose to 5-hydroxymethylfurfural. The yield of 5-hydroxymethylfurfural prepared by hydrolyzing cellulose and glucose is low, and fructose can generate high-yield 5-hydroxymethylfurfural under the catalysis of a very small amount of acid. Therefore, the isomerization of glucose to fructose is considered to be the main limiting step in the hydrolysis of cellulose or glucose to produce 5-hydroxymethylfurfural. Roman-Leshkov et al use Sn-Beta to catalyze glucose isomerization fructose reaction and obtain better catalytic effect, and the result shows that the metal Sn center can form a cyclic intermediate with adjacent hydroxyl and carbonyl in ring-opened glucose molecules, so that hydrogen migration is facilitated, the reaction activation energy is reduced, and the isomerization reaction is facilitated (Roman-Leshkov. Y, Angew. chem. int. Ed., 2010, 49, 8954).
At present, no palladium-molybdenum bimetallic active center catalyst for preparing 5-hydroxymethylfurfural by directly catalyzing cellulose is reported. The palladium-molybdenum bimetallic catalyst prepared by changing catalytic active sites through the synergistic effect of bimetallic active centers can be used for catalyzing cellulose hydrolysis in an environment-friendly aqueous phase to directly obtain high-yield 5-hydroxymethylfurfural.
In addition, the synthesized palladium-molybdenum bimetallic catalyst is used for directly catalyzing a cellulose source to prepare 5-hydroxymethylfurfural as a brand new experimental scheme, the preparation needs to be carried out manually at present, and due to the fact that the whole experimental process is long in time, personnel need to guard and operate for a long time. At present, a container of a flow chemical reaction is mainly a reaction kettle, but the reaction kettle cannot carry out roasting flow work with the same effect, and meanwhile, in order to strengthen the control on the experiment time and the flow, the influence of interference of human factors on the experiment is reduced, and the preparation process of the catalyst is suitable for carrying out the experiment by utilizing automatic equipment. But no experimental equipment suitable for this synthetic process has been found.
Disclosure of Invention
In view of the above, the present invention aims to provide a palladium-molybdenum bimetallic catalyst for catalyzing direct hydrolysis of cellulose to prepare 5-hydroxymethylfurfural, wherein the catalyst has strong thermodynamic stability and chemical stability.
It is another object of the present invention to provide a method for preparing a palladium-molybdenum bimetallic catalyst.
The invention also aims to provide equipment for preparing the palladium-molybdenum bimetallic catalyst, which has high automation control degree, can reduce the personnel utilization rate and has high experimental repeatability.
The invention also aims to provide the application of the palladium-molybdenum bimetallic catalyst, which can be used for directly catalyzing and hydrolyzing the cellulose source to prepare the 5-hydroxymethylfurfural and has better yield and selectivity for preparing the 5-hydroxymethylfurfural by hydrolyzing the cellulose source.
In order to achieve the purpose of the invention, the technical scheme is as follows:
a preparation method of a palladium-molybdenum bimetallic catalyst comprises the following steps:
(1) NaAlO is added2The first alkali liquor and the deionized water are mixed according to the molar ratio of 1: (0.5-10): (50-1000) and mixing according to the proportion of SiO under stirring2With NaAlO2In a molar ratio of 1: (10-40) adding SiO2Crystallizing, filtering, washing, drying and roasting after crystallization is finished to prepare the sodium mordenite;
wherein the crystallization temperature is 100-;
(2) the sodium mordenite, a template agent, a second alkali solution, an alcohol solution and deionized water are mixed according to a molar ratio of 1: (0.1-50): (1-100): (1-700): (200-2000), filtering and washing the product after the alkalization treatment with deionized water for many times until the pH value of the filtrate is neutral, and then drying and roasting to prepare the hydrogen-type mordenite;
wherein the alkalization treatment temperature is 10-200 ℃, the alkalization treatment time is 10-48h, the drying temperature is 50-100 ℃, the drying time is 1-24h, the roasting temperature is 400-;
(3) mixing a palladium source and a molybdenum source according to a molar ratio of palladium to molybdenum of 1: (1-10) preparing a palladium-molybdenum mixed solution, adding the hydrogen-type mordenite into the palladium-molybdenum mixed solution, carrying out an ion exchange reaction under a stirring condition, and then filtering, washing, drying and roasting to obtain a palladium-molybdenum bimetallic catalyst;
wherein the ion exchange reaction temperature is 10-100 ℃, the reaction time is 5-48h, the drying temperature is 50-100 ℃, the drying time is 1-24h, the roasting temperature is 400-.
As a further improvement of the invention, the first alkali solution and the second alkali solution are at least one of sodium hydroxide solution, potassium hydroxide solution and ammonia water.
As a further improvement of the invention, the first alkali solution is 2mol/L sodium hydroxide solution, and the second alkali solution is ammonia water with the mass fraction of 20-50 wt%.
As a further improvement of the invention, the template agent is cetyl trimethyl ammonium bromide template agent.
As a further improvement of the invention, in the step (2), the alcohol solution is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol and decanol.
As a further improvement of the present invention, in the step (3), the palladium source is at least one of palladium nitrate, palladium acetate, chloropalladic acid, palladium chloride and palladium sulfate, and the molybdenum source is at least one of ammonium molybdate and sodium molybdate.
As a further improvement, the palladium-molybdenum bimetallic catalyst can be used for directly catalyzing and hydrolyzing a cellulose source to prepare 5-hydroxymethylfurfural in one step, and the specific application steps are as follows: and (2) mixing the palladium-molybdenum bimetallic catalyst, a cellulose source and deionized water according to a mass ratio of 1: (4-200): (100-1000), performing nitrogen replacement for many times, heating for catalytic reaction, and filtering to obtain a 5-hydroxymethylfurfural solution; wherein the catalytic reaction temperature is 80-400 ℃, the catalytic reaction pressure is 1-10 MPa, and the catalytic reaction time is 1-5 h.
As a further improvement of the invention, the cellulose source can be one or more of cellulose raw materials and glucose polymers, wherein the cellulose raw materials comprise corn straws, poplar, hemp straws and beech, and the glucose polymers comprise microcrystalline cellulose and cellobiose.
The utility model provides an equipment for preparing palladium molybdenum bimetallic catalyst, includes reaction vessel moving module, reinforced stirring module, filters washing module, muffle furnace, control module.
The reaction vessel moving module is used for moving the reaction vessel to different experimental stations and comprises an installation mainboard, a left-right moving module, a front-back guide cylinder and a gas claw for clamping the reaction vessel, wherein the installation mainboard is provided with the left-right moving module, the front-back guide cylinder is installed on a sliding part of the left-right moving module through a cylinder installation plate, and the gas claw is installed on the sliding part of the front-back guide cylinder through a gas claw installation plate;
the feeding and stirring module comprises a temperature control platform, a feeding air cylinder, a stirring lifting air cylinder, a stirrer motor and a charging box, wherein the temperature control platform, the feeding air cylinder and the charging box are all installed on the installation mainboard, the reaction vessel is arranged in a placing groove on the temperature control platform, the stirring lifting air cylinder is installed on the telescopic end of the feeding air cylinder through a feeding air cylinder connecting plate, a stirrer guide part is installed on the telescopic end of the stirring lifting air cylinder, the stirrer motor is installed on the stirrer guide part, the output end of the stirrer motor penetrates through the charging box and is connected with the stirrer, and the charging box is provided with a feeding motor and a feeding wheel;
the filtering and washing module comprises a liquid adding cylinder, the liquid adding cylinder is installed on an installation mainboard, a liquid adding cylinder connecting plate is installed at the telescopic end of the liquid adding cylinder, a filter lifting cylinder is installed at the upper end of the liquid adding cylinder connecting plate, a liquid adding cover is installed at the front end of the liquid adding cylinder, a filter installing plate is installed at the output end of the filter lifting cylinder, a through hole for a filter connecting pipe to pass through is formed in the center of the liquid adding cover, one end of the filter connecting pipe is connected with a peristaltic pump through a liquid path pipe, the other end of the filter connecting pipe is connected with a filter, a liquid path hole for installing a 5-channel liquid adding pipe is formed in the liquid adding cover, one end of the 5-channel liquid adding pipe passes through the liquid path hole of the liquid adding cover, the other end of the 5-channel liquid adding pipe is connected with the peristaltic pump through the liquid path pipe, the peristaltic pump is respectively connected with a liquid storage bottle and a waste liquid bottle, and the peristaltic pump respectively conveys liquid of the 5-channel liquid adding pipes to a reaction vessel, the peristaltic pump discharges the reagent in the reaction vessel to a waste liquid bottle through the filter;
the muffle furnace is installed on the installation main board, the height of the bottom in the muffle furnace is flush with a placing groove which is used for placing a reaction vessel and arranged on the temperature control platform, and the front part of the muffle furnace is flush with the temperature control platform after the muffle furnace opens the door so as to avoid collision.
Control module, including motor controller, solenoid valve controller, motion control ware and temperature controller, it passes through motor controller control to remove the movable mould group, cylinder, liquid feeding cylinder, filter are raised to front and back direction cylinder, gas claw, reinforced cylinder, stirring and are raised the cylinder and pass through trachea connection electromagnetism valves, and the solenoid valve is controlled through solenoid valve controller, reinforced motor, agitator motor, peristaltic pump, muffle furnace gate are controlled through motion control ware, muffle furnace, temperature control platform's temperature is controlled through temperature controller.
The muffle furnace is an automatic door muffle furnace, the furnace door can be controlled by the motion controller to move up and down, and the temperature of the muffle furnace body can be controlled by the temperature controller.
The reaction vessel is made of nickel-based corrosion-resistant alloy, and can meet the requirements of high-temperature roasting at 600 ℃ and normal-temperature reagent experiments.
As a further improvement of the invention, the reaction vessel can be clamped by the gas claw and moves back and forth and left and right under the action of the left and right moving module and the front and back guide cylinder.
As a further improvement of the invention, the liquid feeding cover is in a disc shape matched with the reaction vessel in size, the liquid feeding cylinder can drive the 5-channel liquid feeding pipe and the filter to move up and down, the liquid feeding cover can cover the reaction vessel when moving downwards, the filter lifting cylinder can drive the filter to move up and down, and the reaction vessel can be prevented from moving and colliding when the telescopic ends of the liquid feeding cylinder and the filter lifting cylinder move to the highest position.
The invention has the beneficial effects that: according to the invention, the reaction mechanism of preparing 5-hydroxymethylfurfural by hydrolyzing a cellulose source is researched, and the reaction process is controlled by different types of acid active centers: through temperature control, subcritical water is dissociated to generate hydrogen ions, the hydrogen ions are used as two processes of cellulose hydrolysis with high protonic acid catalytic reaction rate to generate glucose and fructose dehydration to generate 5-hydroxymethylfurfural; the regulation and control of the active center of the catalyst are realized by the synergistic effect of palladium and molybdenum, and the catalyst is used as a rate control process for generating fructose by catalyzing the isomerization of glucose with Lewis acid.
The prepared palladium-molybdenum bimetallic catalyst has stronger thermodynamic stability and chemical stability, can directly catalyze and hydrolyze a cellulose source to prepare 5-hydroxymethylfurfural, and has better yield and selectivity for preparing 5-hydroxymethylfurfural by hydrolyzing the cellulose source.
The equipment for preparing the palladium-molybdenum bimetallic catalyst can strengthen the control on the experiment time and the process, reduce the influence of human factor interference on the experiment, reduce the utilization rate of personnel and have high experiment repeatability.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of the preparation of the palladium-molybdenum bimetallic catalyst of the present invention;
FIG. 2 is a schematic structural view of an apparatus for preparing a palladium-molybdenum bimetallic catalyst according to the present invention;
FIG. 3 is a second perspective view schematically illustrating an apparatus for preparing a palladium-molybdenum bimetallic catalyst according to the present invention;
FIG. 4 is a schematic structural view of the apparatus for preparing a palladium-molybdenum bimetallic catalyst of the present invention involving a feed stirring module;
FIG. 5 is a schematic structural view of an apparatus for preparing a palladium-molybdenum bimetallic catalyst according to the present invention, involving a filtration and washing module;
FIG. 6 is a schematic diagram of a second perspective structure of an apparatus for preparing a palladium-molybdenum bimetallic catalyst according to the present invention involving a filtration and washing module;
FIG. 7 is a schematic diagram of a control module;
FIG. 8 is a TEM image of a palladium-molybdenum bimetallic catalyst, wherein (a) is a topographical feature of the catalyst, and (b) is a microscopic structure of the catalyst.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. 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 application.
The cellulose source used in the invention can be cheap and easily available biomass raw materials such as crops and the like, so that the biomass raw materials can be recycled, waste is turned into wealth, the wide raw material source and the environment-friendly preparation process can greatly improve the problem of environmental pollution, and the cellulose source has practical and far-reaching significance for promoting the sustainable development of agricultural ecological economy and energy. The preparation process is controlled by a computer by utilizing automatically designed automation equipment, and the preparation method is simple and convenient to operate, convenient to implement and high in repeatability. The prepared palladium-molybdenum bimetallic catalyst has high catalytic activity, is easy to separate and can be repeatedly used, and the post-treatment is simple and convenient. The reaction system avoids the use of organic solvents, is green and environment-friendly, and has high cellulose source conversion rate (> 97%) and high 5-hydroxymethylfurfural yield (> 48%).
Based on the high catalytic activity and pollution-free characteristic of the supported palladium-molybdenum bimetallic solid acid catalyst and the physicochemical characteristic and environmental protection characteristic of water, a silicon source and an aluminum source in a proper proportion are dissolved and crystallized, and sodium mordenite is prepared after drying and roasting; then, sodium mordenite is subjected to alkalization treatment, pore Si is selectively removed so as to improve the pore structure of the framework, and hydrogen mordenite is prepared after drying and roasting; replacing a Bronsted acid site on the surface of the mordenite with a Lewis acid site by adopting an ion exchange method to obtain a palladium-molybdenum bimetallic catalyst with synergistic action of palladium and molybdenum; finally, the special physicochemical properties of high-temperature water are utilized, and the processes of hydrolyzing cellulose to generate glucose, isomerizing the glucose to generate fructose, dehydrating the fructose and the like are catalyzed by the Lewis acid synergistic effect and catalytic activity of palladium and molybdenum on the surface of the catalyst. Compared with other catalysts, the Lewis acid position of the palladium-molybdenum bimetallic catalyst can effectively catalyze cellulose to hydrolyze, and simultaneously selectively inhibit the side reaction of fructose and the hydrolysis of 5-hydroxymethylfurfural, thereby obtaining a high-yield 5-hydroxymethylfurfural solution. The preparation process has high automation control degree and high experimental repeatability; the reaction system is environment-friendly, high in conversion rate and high in product yield, has wide application prospect, and provides a new idea for industrialization of high-value utilization of cellulose.
Example 1
A preparation method of a palladium-molybdenum bimetallic catalyst comprises the following steps:
(1) NaAlO is added2The first alkali liquor and the deionized water are mixed according to the molar ratio of 1: (0.5-10): (50-1000) and mixing according to the proportion of SiO under stirring2With NaAlO2In a molar ratio of 1: (10-40) adding SiO2Crystallizing, filtering, washing, drying and roasting after crystallization is finished to prepare the sodium mordenite;
wherein the crystallization temperature is 100-;
(2) the sodium mordenite, a template agent, a second alkali solution, an alcohol solution and deionized water are mixed according to a molar ratio of 1: (0.1-50): (1-100): (1-700): (200-2000), filtering and washing the product after the alkalization treatment with deionized water for many times until the pH value of the filtrate is neutral, and then drying and roasting to prepare the hydrogen-type mordenite;
wherein the alkalization treatment temperature is 10-200 ℃, the alkalization treatment time is 10-48h, the drying temperature is 50-100 ℃, the drying time is 1-24h, the roasting temperature is 400-;
(3) mixing a palladium source and a molybdenum source according to a molar ratio of palladium to molybdenum of 1: (1-10) preparing a palladium-molybdenum mixed solution, adding the hydrogen-type mordenite into the palladium-molybdenum mixed solution, carrying out an ion exchange reaction under a stirring condition, and then filtering, washing, drying and roasting to obtain a palladium-molybdenum bimetallic catalyst;
wherein the ion exchange reaction temperature is 10-100 ℃, the reaction time is 5-48h, the drying temperature is 50-100 ℃, the drying time is 1-24h, the roasting temperature is 400-.
The first alkali liquor and the second alkali liquor are at least one of sodium hydroxide solution, potassium hydroxide solution and ammonia water.
The first alkali liquor is 2mol/L sodium hydroxide solution, and the second alkali liquor is 20-50 wt% ammonia water.
The template agent is cetyl trimethyl ammonium bromide template agent.
In the step (2), the alcohol solution is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol and decanol.
In the step (3), the palladium source is at least one of palladium nitrate, palladium acetate, chloropalladic acid, palladium chloride and palladium sulfate, and the molybdenum source is at least one of ammonium molybdate and sodium molybdate.
Example 2
As shown in fig. 2 to 7, an apparatus for preparing a palladium-molybdenum bimetallic catalyst includes:
as shown in fig. 2, the reaction vessel moving module is used for moving the reaction vessel 8 to different experimental stations, and includes an installation main board 1, a left-right moving module 3, a front-back guide cylinder 5 and a gas claw 7 for clamping the reaction vessel 8, the installation main board 1 is provided with the left-right moving module 3, the front-back guide cylinder 5 is installed on a sliding portion of the left-right moving module 3 through a cylinder installation board 4, and the gas claw 7 is installed on a sliding portion of the front-back guide cylinder 5 through a gas claw installation board 6;
as shown in fig. 3-5, the feeding and stirring module includes a temperature control platform 9, a feeding cylinder 10, a stirring and raising cylinder 12, a stirrer 13, a stirrer motor 15 and a charging box 16, wherein the temperature control platform 9, the feeding cylinder 10 and the charging box 16 are all mounted on the mounting main board 1, the reaction vessel 8 is disposed in a placement slot on the temperature control platform 9, the stirring and raising cylinder 12 is mounted on a telescopic end of the feeding cylinder 10 through a feeding cylinder connecting plate 11, a stirrer guide 14 is mounted on the telescopic end of the stirring and raising cylinder 12, the stirrer guide 14 is mounted with the stirrer motor 15, an output end of the stirrer motor 15 passes through the charging box 16 and is connected with the stirrer 13, and the charging box 16 is mounted with a feeding motor 17 and a feeding wheel 18;
as shown in fig. 4-5, the filtering and washing module comprises a liquid feeding cylinder 19, the liquid feeding cylinder 19 is installed on the installation main board 1, a liquid feeding cylinder connecting plate 20 is installed on the telescopic end of the liquid feeding cylinder 19, a filter lifting cylinder 21 is installed at the upper end of the liquid feeding cylinder connecting plate 20, a liquid feeding cover 28 is installed at the front end, a filter installation plate 22 is installed at the output end of the filter lifting cylinder 21, a through hole for the filter connecting pipe 23 to pass through is formed in the center of the liquid feeding cover 28, one end of the filter connecting pipe 23 is connected with a peristaltic pump 26 through a liquid path pipe 29, the other end of the filter connecting pipe 23 is connected with a filter 25, a liquid path hole for installing a 5-channel liquid feeding pipe 24 is formed in the liquid feeding cover 28, one end of the 5-channel liquid feeding pipe 24 passes through the liquid path hole of the liquid feeding cover 28, the other end of the filter connecting pipe 29 is connected with the peristaltic pump 26, the peristaltic pump 26 is respectively connected with a liquid storage bottle 27 and a waste liquid bottle 30 through the liquid path pipe 29, the peristaltic pump 26 respectively conveys the liquid in the 5 liquid storage bottles 27 to the reaction vessel 8 through the 5-channel liquid adding pipe 24, and the peristaltic pump 26 discharges the reagent in the reaction vessel 8 to the waste liquid bottle 30 through the filter 25;
as shown in fig. 2, the muffle 2 is mounted on the mounting main board 1, the height of the bottom inside the muffle 2 is flush with a placing groove for placing the reaction vessel 8 on the temperature control platform 9, and the front of the muffle 2 is flush with the temperature control platform 9 after the door is opened, so as to avoid collision.
As shown in fig. 7, the control module schematic diagram comprises a motor controller, a solenoid valve controller, a motion controller and a temperature controller, the left and right movement module 3 is controlled by the motor controller, the front and back guide cylinder 5, the gas claw 7, the charging cylinder 10, the stirring lifting cylinder 12, the liquid feeding cylinder 19 and the filter lifting cylinder 21 are connected with the solenoid valve group through a gas pipe, the solenoid valve is controlled by the solenoid valve controller, the charging motor 17, the stirrer motor 15, the peristaltic pump 26 and the muffle 2 furnace door are controlled by the motion controller, and the temperature of the muffle 2 and the temperature control platform 9 is controlled by the temperature controller.
The muffle furnace 2 is an automatic door muffle furnace 2, the furnace door can be controlled by a motion controller to move up and down, and the furnace body temperature of the muffle furnace 2 can be controlled by a temperature controller.
The reaction vessel 8 is made of nickel-based corrosion-resistant alloy and can meet the requirements of high-temperature roasting at 600 ℃ and normal-temperature reagent experiments.
As shown in fig. 2, the reaction cuvette 8 can be held by the gas claw 7 and moved back and forth and left and right by the left and right movement module 3 and the front and back guide cylinder 5.
The liquid feeding lid 28 for with 8 size assorted discs of reaction vessel, liquid feeding cylinder 19 can drive 5 passageway liquid feeding pipes 24 and filter 25 and reciprocate, can cover reaction vessel 8 when liquid feeding lid 28 moves down, the cylinder 21 is raised to the filter can drive filter 25 and reciprocate, can avoid reaction vessel 8 to remove when liquid feeding cylinder 19 and the flexible end that the cylinder 21 was raised to the filter move to the highest position and bump.
Example 3
As shown in fig. 2, the reaction cuvette 8 may be held by the gas claw 7 and moved back and forth and left and right by the left and right movement module 3 and the front and rear guide cylinders 5. The left-right moving module 3 moves to a first position corresponding to a reaction vessel 8 feeding and stirring position, the left-right moving module 3 moves to a second position corresponding to a reaction vessel 8 filtering and washing position, and the left-right moving module 3 moves to a third position corresponding to a reaction vessel 8 roasting position.
A preparation method of a palladium-molybdenum bimetallic catalyst comprises the following steps:
taking 29g of SiO2(station II), 20 g of hexadecyl trimethyl ammonium bromide template (CTMABr) (station III) and 2g of microcrystalline cellulose powder (station IV) are respectively filled into 3 stations of a charging box 16, which are respectively marked as station II, station III and station IV, and 55 mL of sodium hydroxide solution (bottle V) with the mole fraction of 2mol/L, 2000 mL of deionized water (bottle VI) and 500 mL of deionized water (bottle VI) are takenEthanol (bottle VII), 50 mL of palladium nitrate (bottle VIII) with a molar fraction of 0.01 mol/L and 20 mL of ammonium molybdate solution (bottle IX) with a molar fraction of 0.1 mol/L are respectively put into 5 liquid storage bottles 27, which are respectively marked as peristaltic pumps 26V, VI, VII, VIII and IX corresponding to the bottle V, 26VI, 26VII, 26VIII and 26IX, and a filter 25 is connected with the peristaltic pump 26V and a waste liquid bottle 30 through pipelines.
2g of NaAlO was taken2Placed in reaction vessel 8, place reaction vessel 8 in temperature control platform 9's standing groove, peristaltic pump 26V begins work and adds 55 mL sodium hydroxide solution to reaction vessel 8, peristaltic pump 26VI work adds a small amount of deionized water to reaction vessel 8, remove and remove to the second position in the module 3 about, leading cylinder 5 stretches out around, leading cylinder 5 withdraws around after the gas claw 7 centre gripping reaction vessel 8, it stretches out to remove leading cylinder 5 around after removing to the first position in the module 3 about, gas claw 7 is opened and is placed reaction vessel 8 in temperature control platform 9's standing groove, agitator motor 15 work, 16 station II feed motor 17 of the cartridge that charges drives under 18 work of feeding wheel and add 29g SiO2And stirring the gel mixture for 40min by a stirrer 13, heating the temperature control platform 9 to 200 ℃ for reaction for 30h, and naturally cooling to room temperature after the reaction is finished. The reaction cuvette moving module holds the reaction cuvette 8 to move to the second position, and the peristaltic pumps 26VI and 26X operate to wash the product to neutrality with deionized water multiple times. And (3) drying for 3h at the temperature of 100 ℃ by the temperature control platform 9, clamping the reaction vessel 8 by the reaction vessel moving module, moving the reaction vessel 8 to a third position, placing the reaction vessel 8 in the muffle 2, closing the muffle 2 door, and roasting for 9h at the temperature of 600 ℃ to obtain the sodium mordenite.
400 mL of ammonia water solution (V) with the mass fraction of 40 wt% and 2000 mL of deionized water (VI) are respectively filled into a bottle V and a bottle VI again and correspond to a peristaltic pump 26V and a peristaltic pump 26VI, the prepared sodium mordenite is placed into a reaction vessel 8, a reaction vessel moving module is operated to clamp the reaction vessel 8 and move to a second position, 400 mL of ammonia water solution, 500 mL of ethanol and a proper amount of deionized water are obtained, reagents are added corresponding to the work of the peristaltic pump 26V, the peristaltic pump 26VI and the peristaltic pump 26VII, the reaction vessel moving module clamps the reaction vessel 8 and moves to a first position, a charging box 16, a station III and a charging motor 17 work, 20 g of hexadecyl trimethyl ammonium bromide template agent (CTMABr) are added, and a temperature control platform 9 is heated to 30 ℃ for reaction for 24 hours. After the reaction is finished, the reaction dish moving module clamps the reaction dish 8 and moves to the second position, and the peristaltic pump 26VI and the peristaltic pump 26X work and are repeatedly washed by deionized water until the reaction dish is neutral. And heating the temperature control platform 9 to 80 ℃, drying for 12h, clamping the reaction vessel 8 by the reaction vessel moving module, moving the reaction vessel 8 to a third position, placing the reaction vessel 8 in the muffle 2, closing the muffle 2 door, and roasting for 5h at 600 ℃ to obtain the hydrogen-type mordenite.
Placing the prepared hydrogen-type mordenite in a reaction vessel 8, clamping the reaction vessel 8 by a reaction vessel moving module, moving the reaction vessel 8 to a second position, adding reagents corresponding to the working of a peristaltic pump 26VIII and a peristaltic pump 26IX to obtain 50 mL of palladium nitrate with the molar fraction of 0.01 mol/L and 20 mL of ammonium molybdate solution with the molar fraction of 0.1 mol/L, heating a temperature control platform 9 to 80 ℃, and reacting for 24 hours under the stirring condition. And after the reaction is finished, the temperature control platform 9 is rapidly cooled to room temperature, the reaction vessel moving module clamps the reaction vessel 8 and moves to the second position, and the peristaltic pump 26VI and the peristaltic pump 26X work and are repeatedly washed by deionized water to be neutral. And heating the temperature control platform 9 to dry for 5 hours at 80 ℃, clamping the reaction vessel 8 by the reaction vessel moving module to move to a third position, placing the reaction vessel 8 in the muffle 2, closing the muffle 2 door, and roasting for 9 hours at 600 ℃ to obtain the palladium-molybdenum bimetallic catalyst.
Fig. 8 is a TEM image of the resulting palladium molybdenum bimetallic catalyst, and it can be seen that palladium and molybdenum are supported on the carrier (sodium mordenite and hydrogen mordenite) and that the surface dispersibility is relatively good.
Example 4
The palladium-molybdenum bimetallic catalyst disclosed by the invention is applied to one-step preparation of 5-hydroxymethylfurfural by directly catalyzing and hydrolyzing a cellulose source.
200 mg of the prepared palladium-molybdenum bimetallic catalyst is placed in a reaction vessel 8, the reaction vessel 8 is clamped by a reaction vessel moving module to move to a first position, 2g of microcrystalline cellulose powder (IV) is added to a charging box 16 station IV corresponding to the work of a charging motor 17, the reaction vessel 8 is clamped by the reaction vessel moving module to move to a second position, 30 mL of deionized water is added after a peristaltic pump 26VI is opened, and after nitrogen conversion for many times, a temperature control platform 9 is heated to 350 ℃ for reaction for 3 hours. After the reaction is finished, the equipment gives out a prompt sound. The reaction vessel 8 is taken out and filtered to obtain a supernatant. The yield of 5-hydroxymethylfurfural was 52% by High Performance Liquid Chromatography (HPLC).
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement, component separation or combination and the like made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.