阅读说明：本技术 新型固体酸催化剂一锅多步催化生物质衍生糠醛转化为γ-戊内酯的制备方法 (Preparation method for converting biomass derived furfural into gamma-valerolactone by novel solid acid catalyst one-pot multi-step catalysis ) 是由 吕学斌 韩怡雯 柏慧 叶磊 于 2019-10-16 设计创作，主要内容包括：本发明公开一种新型固体酸催化剂一锅多步催化生物质衍生糠醛转化为γ-戊内酯的制备方法,包括如下步骤：将0.3g-0.7g硝酸锆生成的前驱物与蒸馏水均匀混合；将ZSM-5载体加入上一步配置的溶液中；加入6g-10g尿素用于调节PH；将混合溶液加热至95℃并剧烈搅拌5小时；将溶液过滤,用蒸馏水洗涤,然后在90℃下干燥14小时；在烘箱中以550℃条件煅烧4小时；反应前向反应釜中通入氮气,用以排出釜内的空气,使反应环境保持在氮气氛围下；将异丙醇和水混合组成的20mL溶液加入不锈钢高压反应釜中,加入糠醛,固体酸催化剂和磁力搅拌转子,设置实验条件进行反应；反应完成后,将反应器置于冷水中以迅速冷却至室温,将催化剂回收。(The invention discloses a preparation method for converting biomass derived furfural into gamma-valerolactone by a novel solid acid catalyst through one-pot multi-step catalysis, which comprises the following steps: uniformly mixing a precursor generated by 0.3g-0.7g of zirconium nitrate with distilled water; adding a ZSM-5 carrier into the solution prepared in the last step; adding 6g-10g of urea for regulating the PH; heating the mixed solution to 95 ℃ and stirring vigorously for 5 hours; the solution was filtered, washed with distilled water and then dried at 90 ℃ for 14 hours; calcining the mixture in an oven at 550 ℃ for 4 hours; before the reaction, introducing nitrogen into the reaction kettle for discharging air in the kettle to keep the reaction environment in a nitrogen atmosphere; adding 20mL of solution formed by mixing isopropanol and water into a stainless steel high-pressure reaction kettle, adding furfural, a solid acid catalyst and a magnetic stirring rotor, and setting experimental conditions for reaction; after the reaction was completed, the reactor was placed in cold water to be rapidly cooled to room temperature, and the catalyst was recovered.)

1. The preparation method for converting biomass derived furfural into gamma-valerolactone by using the novel solid acid catalyst through one-pot multi-step catalysis is characterized by comprising the following steps of:

1) uniformly mixing a precursor generated by 0.3g-0.7g of zirconium nitrate with distilled water;

2) adding a ZSM-5 carrier into the solution prepared in the last step;

3) adding 6g-10g of urea for regulating the PH;

4) heating the mixed solution to 95 ℃ and stirring vigorously for 5 hours;

5) the solution was filtered, washed with distilled water and then dried at 90 ℃ for 14 hours;

6) calcining the mixture in an oven at 550 ℃ for 4 hours;

7) before the reaction, introducing nitrogen into the reaction kettle for discharging air in the kettle to keep the reaction environment in a nitrogen atmosphere;

8) adding 20mL of solution formed by mixing isopropanol and water into a stainless steel high-pressure reaction kettle, adding furfural, a solid acid catalyst and a magnetic stirring rotor, and setting experimental conditions for reaction;

9) after the reaction was completed, the reactor was placed in cold water to be rapidly cooled to room temperature, and the catalyst was recovered to obtain a solution containing γ -valerolactone.

2. The method according to claim 1, wherein the ratio of Si to Al in step 2) is 27.

3. The preparation method of claim 1, wherein the mass ratio of urea to ZSM-5 molecular sieve in the step 3) is 5-10g of molecular sieve to 1g of urea, and the pH is adjusted by heating urea to decompose into ammonia water, so that the pH is controlled to be 9-11.6.

4. The method according to claim 1, wherein the zirconium nitrate is generated as a precursor containing Zr ions in an equimolar amount in the step 2).

5. The method of claim 1, wherein the isopropanol in step 8) is miscible with water in any ratio.

6. The method as claimed in claim 1, wherein the amount of the catalyst used in the step 8) is controlled to be 0.15g to 0.6 g.

7. The method of claim 1, wherein the metal loading of step 2) is controlled to be in the range of 5 wt% to 20 wt%.

8. The method as set forth in claim 1, wherein the reaction temperature in the step 8) is controlled to be 125-200 ℃.

9. The preparation method according to claim 1, wherein the reaction time of the step 8) is controlled to 16 to 22 hours.

10. The preparation method according to claim 1, wherein the solid acid catalyst HZSM-5-ZrO2 in step 8) is recovered and recycled.

Technical Field

The invention belongs to the field of preparation of acid catalysts, and relates to a novel multifunctional solid acid catalyst HZSM-5-ZrO₂In particular to a preparation method for catalyzing furfural to be catalytically converted into gamma-valerolactone.

Background

The large-scale utilization of fossil resources has greatly promoted the development of human society and economy, while also causing many inevitable derivative problems including global warming, air pollution and energy shortage to improve environmental deterioration pollution and global energy crisis, and researchers have been gradually seeking to develop new green renewable resource utilization strategies in recent years. As a natural clean renewable energy source, the biomass energy has wide sources, abundant reserves and low price, can be converted into various important high-value-added fuels and chemicals, has great potential to replace the traditional fossil energy, and has attracted extensive attention in academia and industry for exploring a more effective biomass resource utilization method. Gamma valerolactone has received much attention from researchers because of its excellent physical properties. The basic properties of gamma-valerolactone mainly include high boiling point, high flash point, low melting point, low toxicity and the like. The gamma-valerolactone can participate in various reactions, and is widely applied to the production of fuel additives, medical intermediates, high-grade olefin fuels, green regenerated solvents, nylon intermediates and the like. The reaction for preparing gamma-valerolactone from furfural involves two hydrolysis reactions and one hydrogenation reaction. At present, gamma-valerolactone is prepared from a biomass platform compound furfural, hydrogen is mostly used as a hydrogen donor, liquid acid and a composite catalyst are mostly used as a catalyst, noble metal is introduced, and the like, so that the problems of poor safety, difficult recovery of the catalyst, high manufacturing cost and the like are caused. The invention uses molecular sieve ZSM-5 loaded ZrO₂The single bifunctional solid acid catalyst is prepared and used in the reaction of converting furfural into gamma-valerolactone.

Disclosure of Invention

In order to solve the problems of the existing catalyst. The invention focuses on a novel single dual-function solid acid catalyst, and uses a molecular sieve to load non-noble metal oxide ZrO₂The catalyst is synthesized by using a coprecipitation method, and the dried standby catalyst is white powder.

The invention adopts the following technical scheme that a preparation method for converting biomass derived furfural into gamma-valerolactone by a novel solid acid catalyst through one-pot multi-step catalysis comprises the following steps:

1) uniformly mixing a precursor generated by 0.3g-0.7g of zirconium nitrate with distilled water;

2) adding a ZSM-5 carrier into the solution prepared in the last step;

3) adding 6g-10g of urea for regulating the PH;

4) heating the mixed solution to 95 ℃ and stirring vigorously for 5 hours;

5) the solution was filtered, washed with distilled water and then dried at 90 ℃ for 14 hours;

6) calcining the mixture in an oven at 550 ℃ for 4 hours;

7) before the reaction, introducing nitrogen into the reaction kettle for discharging air in the kettle to keep the reaction environment in a nitrogen atmosphere;

8) adding 20mL of solution formed by mixing isopropanol and water into a stainless steel high-pressure reaction kettle, adding furfural, a solid acid catalyst and a magnetic stirring rotor, and setting experimental conditions for reaction;

9) after the reaction was completed, the reactor was placed in cold water to be rapidly cooled to room temperature, and the catalyst was recovered to obtain a solution containing γ -valerolactone.

The silicon-aluminum ratio in the step 2) is 27.

In the step 3), the mass ratio of the urea to the ZSM-5 molecular sieve is 5-10g of molecular sieve to 1g of urea, and the pH is adjusted by heating and decomposing the urea to form ammonia water, so that the pH is controlled to be 9-11.6.

The precursor containing Zr ions in an equimolar amount is generated from the zirconium nitrate in the step 2).

In the step 8), isopropanol and water are mutually soluble in any proportion.

The dosage of the catalyst in the step 8) is controlled between 0.15g and 0.6 g.

The metal loading in the step 2) is controlled to be 5-20 wt%.

The reaction temperature of the step 8) is controlled at 125-200 ℃.

The reaction time of the step 8) is controlled to be 16-22 h.

And in the step 8), the solid acid catalyst HZSM-5-ZrO2 can be recycled.

The experimental method comprises the following steps:

1. adding 20mL of solution formed by mixing isopropanol and water into a stainless steel high-pressure reaction kettle, adding furfural, a solid acid catalyst and a magnetic stirring rotor, and setting four-level orthogonal experiments of five factors (metal load, catalyst dosage, reaction temperature, reaction time and isopropanol dosage).

2. Before the reaction, nitrogen is introduced into the reaction kettle to exhaust air in the kettle, so that the reaction environment is kept in a nitrogen atmosphere. And screwing down screws of the reaction kettle to keep a closed environment in the kettle, connecting the reaction kettle with a power supply and a temperature sensor, setting the temperature and the reaction time of the reaction kettle, keeping the stirring speed of the magnetons at 500 revolutions per minute, and starting the reaction.

3. After completion of the reaction, the reactor was placed in cold water to be rapidly cooled to room temperature. The catalyst was recovered and a solution containing gamma valerolactone was obtained and awaited testing.

And (3) a product detection method:

1. the furfural and gamma-valerolactone concentrations of the filtrate were determined using a Bio-Rad Aminex HPX-87H column at 65 ℃ using high performance liquid chromatography and a refractive index detector.

2. As a mobile phase, 5mM sulfuric acid aqueous solution was used at a flow rate of 0.6 mL/min.

3. And preparing standard samples with different concentration gradients for fitting standard curves of furfural and gamma-valerolactone.

4. And (5) detecting a product, and calculating the concentration and the yield of the gamma-valerolactone according to the peak area.

Drawings

Fig. 1 is a result based on experimental condition nine in the table.

In the figure: 0.2mL furfural, 15 wt% Zr, 0.4g catalyst, 17.4mL isopropanol, 175 deg.C, 16 hours; only one variable was changed to obtain new reaction conditions and yields.

Detailed Description

The invention is further described below with reference to the following figures and specific examples.

A 20mL solution composed of a furfural and isopropanol mixed solution was added to a high-pressure reaction kettle together with a catalyst, a solid acid catalyst and a magnetic stirring rotor were added, and four-level orthogonal experiments were performed with five factors (metal loading, catalyst amount, reaction temperature, reaction time, and isopropanol addition) as shown in table 1 below. Before the reaction, nitrogen is introduced into the reaction kettle to exhaust air in the kettle, so that the reaction environment is kept in a nitrogen atmosphere. And screwing down screws of the reaction kettle to keep a closed environment in the kettle, connecting the reaction kettle with a power supply and a temperature sensor, setting the temperature and the reaction time of the reaction kettle, keeping the stirring speed of the magnetons at 500 revolutions per minute, and starting the reaction. After completion of the reaction, the reactor was placed in cold water to be rapidly cooled to room temperature. The catalyst was recovered and a solution containing gamma valerolactone was obtained and awaited testing. The furfural and gamma-valerolactone concentrations of the filtrate were determined using a Bio-Rad Aminex HPX-87H column at 65 ℃ using high performance liquid chromatography and a refractive index detector. Testing a product by using a high performance liquid chromatography, firstly preparing 0.05mol/L dilute sulfuric acid solution as a mobile phase, and putting the prepared dilute sulfuric acid solution into a volumetric flask; pouring dilute sulfuric acid into a beaker, placing the beaker into an ultrasonic oscillator, oscillating for 30 minutes, and filtering the solution after oscillation by using a filter membrane to remove bubbles in a mobile phase; opening a high performance liquid chromatography baseline according to an operation program; the flow rate of the mobile phase is controlled to be 0.6 mL/min; and when the base line tends to be stable, injecting by using a sample injection needle, and calculating the concentration and the gamma-valerolactone yield according to the peak area.

Zr can be used as metal with the function of promoting dehydrogenation of hydrogen donor, ZrO2 and CuO or SnO loaded by molecular sieve₂Compared with the prior art, the Zr/ZSM-5 catalyst has obvious catalytic effect, is considered to have the effect of catalyzing furfural to produce gamma-valerolactone, and can complete MPV reaction and acid hydrolysis reaction which are connected in series in the process. The results in table 1 show that different reaction conditions have a large effect on the yield of gamma-valerolactone, and the catalytic performance is the best when the metal loading reaches 15%. Under the conditions of the ninth group (metal loading 15 wt%, catalyst addition 0.4, reaction temperature 175 deg.C, reaction time 16 hours, isopropanol amount 17.4ml) in the table, the yield of gamma-valerolactone reached 49.71%. The possible reasons are that the Zr/ZSM-5 catalyst has proper Bronsted acid sites and Lewis acid sites, the proportion and the number of the B acid sites and the L acid sites are proper, and the catalytic conditions are proper,this ensures that the reaction can proceed relatively well.

Table 1: reaction conditions of Zr/ZSM-5

(a: IPA volume in 20ml solution)

And then, the catalytic effect of the novel multifunctional solid acid catalyst HZSM-5-ZrO2 is optimized in detail.

Reaction conditions suitable for gamma-valerolactone production were further investigated by using a Zr/ZSM-5 catalyst to obtain higher gamma-valerolactone yield, and 10 sets of univariate reactions were continued on the basis of the experimental conditions of set 9 in Table 1 (metal loading 15% wt, catalyst addition 0.4g, reaction temperature 175 ℃, reaction time 16 hours, isopropanol amount 17.4 ml). For example, two sets of reactions for the first univariate correspond to reaction conditions of: 0.2mL of furfural, 10 wt% of Zr or 20 wt% of Zr, 0.4g of catalyst, 17.4mL of isopropanol, 175 ℃ and 16h, wherein the changed conditions are only the change of metal loading, and the change rule of the subsequent experimental conditions is the same as that of the first group. At this time, the yield of gamma-valerolactone was significantly improved, and the yield of most GVL reached 40% or more. It is evident from the figure that the metal loading of Zr on the molecular sieve plays a crucial role in FAL conversion and GVL production, and the effect is significantly reduced for the high metal loading catalyst. The possible reasons are that the loading of the metal on the molecular sieve support has reached saturation, and at this time, if the loading is continuously increased, the pores of the molecular sieve are blocked, the acidity of the molecular sieve is obviously reduced, and the specific surface area of the whole catalyst is reduced, so that the catalytic performance is reduced. In addition, variations in reaction temperature and reaction time had a moderate effect on GVL yield, with the temperature controlled at 165 ℃ and 185 ℃, with minor variations in gamma valerolactone yield. Extending the time from 14 hours to 18 hours, the gamma valerolactone yield increased, thus driving the reaction toward forward progress as the reaction time increased. The amount of catalyst and the amount of IPA had a small effect, indicating that the amount of catalyst added, 0.3g and the amount of IPA used, 18.5ml, had satisfied the conditions required for the reaction under these conditions. By optimizing the Zr/ZSM-5 catalytic conditions, the GVL yield reached a maximum of 52.43% at 175 ℃ for 18 hours using 0.4g of 15 wt% Zr/ZSM-5 as catalyst and 17.4mL of isopropanol as hydrogen donor.