CN106905109A - A kind of method that catalytic hydrogenolysis cellulose produces propane diols - Google Patents

Abstract

The invention relates to a method for producing propylene glycol by hydrothermal hydrogenolysis of cellulose with a catalyst. The specific steps are: adding microcrystalline cellulose and a catalyst in proportion to a reactor, and the reaction temperature is 210°C-240°C, and the reaction time is 15 minutes -45min, 5MPa _- 7MPa H Under the condition of pressure, hydrothermal reaction is carried out, and the catalyst described in the reaction is a catalyst with β molecular sieve as the carrier. The metal carrier is metal Ni and WO ₃ . The invention relates to simple process, convenient operation, and no secondary pollution. Compared with the existing ethylene glycol industrial synthesis route in which ethylene is the reaction raw material, the waste resource utilization is realized, and certain economic and social benefits are obtained.

Description

A method of catalyzing hydrogenolysis of cellulose to produce propylene glycol

technical field

The invention relates to a method for catalyzing hydrogenolysis of cellulose to produce propylene glycol, in particular to a hydrothermal reduction method using cheap metals as reducing agents and catalysts, and belongs to the field of environmental chemical industry.

Background technique

In recent years, the depletion of fossil resources, the increasing demand for energy and the continuous deterioration of the global climate and environment have forced humans to look for renewable new energy sources that can replace fossil resources. Among them, the most likely alternative to fossil fuels is the Biomass for "green coal". Biomass energy has been increasingly valued and developed rapidly because of its good environmental effects such as abundant reserves, recyclability, carbon neutrality, renewability, and no pollution. Among them, cellulose is the most abundant component of biomass. It is the starting material of energy chemical industry and has great development prospects.

Propylene glycol in polyols is an important chemical raw material, which is widely used in the production of polyester fiber (polyester) and antifreeze, and its demand is expected to double in the next few decades. At present, the industry is mainly obtained by the hydration of petroleum ethylene and petroleum propylene oxide ethylene oxide and propylene oxide, that is, firstly obtain olefins with corresponding carbon numbers from petroleum, then obtain alkylene oxides through epoxidation, and finally epoxidize Oxyalkanes undergo hydration reactions to obtain propylene glycol. Therefore, using biomass-based cellulose as a raw material to synthesize propylene glycol can reduce the excessive dependence on petrochemical resources and reduce _CO2 emissions. This process will have a very high atom economy and meet the requirements of green chemistry. The economic value of low-carbon polyols is also huge, for example, the price of ethylene glycol is US$660/ton, and the price of propylene glycol is US$1,500/ton. Therefore, how to improve the conversion of cellulose into low-carbon polyols with high economic value is very important for the efficient utilization of biomass energy.

Contents of the invention

The purpose of the present invention is to provide a method for producing propylene glycol by catalyzing hydrogenolysis of cellulose, so as to realize the conversion of cellulose into high value-added propylene glycol.

In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions:

The method that the catalytic hydrogenolysis of cellulose that the present invention proposes produces propylene glycol, concrete steps are as follows:

(1) Catalyst synthesis

(1.1) Dissolve 0.15-0.25g of phosphotungstic acid (H ₃ O ₁₀ W ₁₂ ·12H ₂ O) in water, then slowly add the solution dropwise to 1g of β molecular sieve, ultrasonicate for 30min, let stand for aging for 12h, and then ℃ for 4 hours, then baked at 550 ℃ for 4 hours;

(1.2) Dissolve 0.25-0.75g nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ 6H ₂ O) in water, then slowly add the solution dropwise to the material synthesized in step (1.1), ultrasonicate for 30min, and stand for aging 12h, then bake at 110°C for 4h, then bake at 550°C for 4h;

(1.3) Reducing the material obtained in step (1.2) in a hydrogen stream at 550°C for 4 hours; to obtain a Ni-W/β catalyst;

Among them: the dosing ratio of phosphotungstic acid and nickel nitrate hexahydrate is 15:5-5:25;

(2) Catalytic reaction

Put the Ni-W/β catalyst, cellulose and water synthesized in step (1.3) in a Teflon jar, and then place it in a high-temperature and high-pressure reactor. The reaction temperature is 210-240°C, and the reaction time is 15-45min. The hydrothermal reduction reaction is carried out under the condition of reaction pressure 5-7MPa, and the cellulose aqueous solution is reduced to a mixture of small molecular organic substances mainly composed of propylene glycol, and then purified and separated to obtain propylene glycol; wherein: the catalyst dosage is 5 mmol/L-15 mmol /L.

In the present invention, propylene glycol with cellulose as the substrate is the main product.

The beneficial effects of the present invention are:

1. The raw material of the present invention is cellulose (such as crop straw) that exists widely in nature and has not been effectively utilized. It has a wide range of sources and has the advantage of low raw material cost. Compared with other technologies that use biomass resources (such as starch and glucose) to produce propylene glycol, it eliminates the possible adverse effects of biomass energy conversion on human food security

2. The reducing agent used in the present invention is cheap and easy to obtain, and the catalyst is also easy to obtain, and the price is relatively cheap.

3. The present invention can be completed through one-step reaction, and has simple process and convenient operation.

4. The present invention can solve the problem of disposal of biodiesel by-product glycerin, and the produced propylene glycol can be used in industry to realize the goal of recycling waste.

5. Using hydrothermal degradation to convert cellulose, the reaction system is environmentally friendly and pollution-free. Water is used as the reaction medium, and no inorganic acids and bases are used in the reaction, which avoids the common environmental pollution problems in the cellulose degradation process.

6. The reaction process of the present invention is simple, and there is no need to carry out acid hydrolysis on cellulose in advance, only by physically grinding the raw materials.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is the TEM image of the catalyst; among them: a, the TEM image of the catalyst at 200 nm scale, b, the TEM image of the catalyst at 100 nm scale, c, the TEM image of the catalyst at 50 nm scale Figure, d, TEM image of the catalyst under 20 nm scale;

Figure 2 is the XRD analysis diagram of the catalyst.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

Equal volume impregnation method to prepare bimetallic catalyst steps:

(1) Dissolve 0.2g of phosphotungstic acid (H ₃ O ₁₀ W ₁₂ 12H ₂ O) in 1.2 mL of water, stir with a cleaned glass rod, and put it into an ultrasonic instrument for about 30 minutes to observe the activity of the active β molecular sieve. Adsorption status, if the adsorption is not uniform, continue to ultrasonic, after the adsorption is good, aging for 12 h, then put it in an oven, dry at 110 °C for 4 h, cool to room temperature, put it into a box-type resistance furnace, and put it in a box-type resistance furnace at 550 °C Roasted under the same conditions for 4 h.

(2) Dissolve 0.35g of nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ 6H ₂ O) in 1.2ml of water, add it to the roasted material in step (1), and repeat ultrasonication, aging, drying and roasting process. Finally, the calcined catalyst was hydrogenated in a tube furnace with a mixture of 5% hydrogen and 95% nitrogen at 500 °C for 4 h. The catalyst prepared by this method is recorded as: 7%Ni-20%W/β.

Accompanying drawing 1 is the TEM topography figure of the bimetallic 7%Ni-20%W/β catalyst prepared in Example 1 under the scales of 200 nm, 100 nm, 50 nm, and 20 nm.

Cellulose catalytic conversion process: Cellulose was vacuum-dried at 105 °C for 12 h before use. The catalytic hydrogenolysis reaction of cellulose is carried out in a stainless steel reactor. Add 1 g of cellulose, 0.3 _g of catalyst and 40 mL of distilled water into the Teflon tank in sequence, and then put the Teflon tank into the stainless steel reaction kettle _; Replace the air in the reactor for about three times, and control the pressure at 6 MPa; put the reactor into the heating and stirring controller, insert a thermocouple to heat up, and stir at a speed of 1000 r/min. When the reaction temperature reaches the set temperature of 240 ℃, start Timing, after 30 minutes of reaction, turn off the heating device. After the reaction, the reactor was cooled to room temperature, and the product was separated by filtration after the pressure was released. The conversion rate of cellulose was 100%, and the yield of propylene glycol reached 19.3%.

Example 2

Under the joint action of Ni-W, the solid residue collected after the reaction in Example 1 was filtered and rinsed with deionized water, and dried in an oven at 70° C. for testing. Using a type ray diffractometer for detection, the 2θ angle range of ray diffraction is 5-80º, and the rotation angle rate is 10º/min. The analysis results show that as shown in Figure 2, the catalytic substances in the catalyst are simple Ni and WO ₃ , The formation of nickel tungstate (NiWO ₄ ) hinders the degradation of cellulose and the formation of polyols.

Example 3

The difference from Example 1 is that the mass of phosphotungstic acid used is 0.15 g, and the synthesis steps of the rest of the catalyst and the catalytic degradation process of cellulose are the same as in Example 1. The 7%Ni-15%W/β catalyst prepared in this example degrades cellulose to produce propylene glycol with a yield of 15.8%, and a cellulose conversion rate of 100%.

Example 4

The difference from Example 1 is that the mass of phosphotungstic acid used is 0.25 g, and the synthesis steps of the rest of the catalyst and the catalytic degradation process of cellulose are the same as in Example 1. The 7%Ni-25%W/β catalyst prepared in this example degrades cellulose to produce propylene glycol with a yield of 7.2%, and a cellulose conversion rate of 92%.

Example 5

The difference from Example 1 is that the mass of nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) used is 0.25 g, and the synthesis steps of the rest of the catalyst and the catalytic degradation process of cellulose are the same as in Example 1. The 5%Ni-20%W/β catalyst prepared in this example degrades cellulose to produce propylene glycol with a yield of 15.8%, and a cellulose conversion rate of 100%.

Example 6

The difference from Example 1 is that the mass of nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) used is 0.45 g, and the synthesis steps of the other catalysts and the catalytic degradation process of cellulose are the same as in Example 1. The 9%Ni-20%W/β catalyst prepared in this example degrades cellulose to produce propylene glycol with a yield of 18.7%, and a cellulose conversion rate of 100%.

Example 7

The difference from Example 1 is that the mass of nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) used is 0.75 g, and the synthesis steps of the other catalysts and the catalytic degradation process of cellulose are the same as in Example 1. The 15%Ni-20%W/β catalyst prepared in this embodiment degrades cellulose to produce propylene glycol with a yield of 3.6%, and a cellulose conversion rate of 89%.

Example 8

The difference from Example 1 is that the reaction temperature is adjusted to 210° C., the catalyst synthesis steps and the rest of the cellulose catalytic degradation process are the same as in Example 1. In this example, the 7%Ni-20%W/β catalyst degrades cellulose to produce propylene glycol with a yield of 16.6%, and a cellulose conversion rate of 100%.

Example 9

The difference from Example 1 is that the reaction temperature is adjusted to 270° C., the catalyst synthesis steps and the rest of the cellulose catalytic degradation process are the same as in Example 1. The productive rate of this embodiment cellulose producing propylene glycol is 17.1%, and the cellulose conversion rate is 100%.

Example 10

The difference from Example 1 is that the reaction time is adjusted to 15 min, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The productive rate of this embodiment cellulose producing propylene glycol is 4.4%, and the cellulose conversion rate is 77%.

Example 11

The difference from Example 1 is that the reaction time is adjusted to 60 minutes, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The productive rate of this embodiment cellulose producing propylene glycol is 18.6%, and the cellulose conversion rate is 100%.

Example 12

The difference from Example 1 is that the reaction pressure is adjusted to 5 MPa, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The productive rate of this embodiment cellulose producing propylene glycol is 15.3%, and the cellulose conversion rate is 90%.

Example 13

The difference from Example 1 is that the reaction pressure is adjusted to 7 MPa, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The productive rate of this embodiment cellulose producing propylene glycol is 18.9%, and the cellulose conversion rate is 100%.

Example 14

The difference from Example 1 is that the amount of the substrate is adjusted to 0.5 g, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The yield of propylene glycol in this catalytic reaction is 17.9%, and the conversion rate of cellulose is 100%.

Example 15

The difference from Example 1 is that the amount of the substrate is adjusted to 2 g, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The yield of propylene glycol in this catalytic reaction is 14.9%, and the conversion rate of cellulose is 87%.

Example 16

The difference from Example 1 is that the stirring speed is adjusted to 100 r/min, the catalyst synthesis steps and the rest of the cellulose catalytic degradation process are the same as in Example 1. The yield of propylene glycol in this catalytic reaction is 13.9%, and the conversion rate of cellulose is 84%.

Example 17

The difference from Example 1 is that the stirring speed is adjusted to 500 r/min, the catalyst synthesis steps and the rest of the cellulose catalytic degradation process are the same as in Example 1. The yield of propylene glycol in this catalytic reaction is 16.9%, and the conversion rate of cellulose is 97%.

Example 18

The difference from Example 1 is that the amount of water used is adjusted to 20 ml, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The yield of propylene glycol in this catalytic reaction is 16.3%, and the conversion rate of cellulose is 94%.

Example 19

The difference from Example 1 is that the amount of water used is adjusted to 60 ml, and the synthesis steps of the catalyst and the rest of the cellulose catalytic degradation process are the same as in Example 1. The yield of propylene glycol in this catalytic reaction is 15.3%, and the conversion rate of cellulose is 100%.

Example 20

The difference from Example 1 is that NaOH, Ca(OH) ₂ , and Ba(OH) ₂ three soluble strong bases were used as base catalysts, and the effects of the type and amount of base catalysts on cellulose degradation were explored. The conversion rate of cellulose in the reaction system with three kinds of alkali catalysts was 100%. The yield of 1, 2-PG was 19.3% when the alkali solution was not strengthened, and the yield of 1, 2-PG was increased after adding the alkali solution. For the catalytic system added with NaOH solution, the change of the concentration of NaOH solution has little effect on the increase of 1,2-PG yield, and the highest yield is 25.5%. For the catalytic system added with Ca(OH)2 solution, the effect is more obvious than that of NaOH system. When the concentration of Ca(OH)2 is 10 mmol/L, the yield of 1,2-PG is as high as 30.1%. When Ba(OH)2 solution was added, the yield of 1,2-PG also increased significantly. When 10 mmol/L Ba(OH)2 solution was added, the yield of 1,2-PG reached 32.5%.

Example 21

The difference from Example 20 is that a series of base-catalyzed reactions were carried out using glucose as a substrate.

Example 22

The 7Ni-20W/β molecular sieve catalytic system was used to explore the cycle performance of the catalyst. After each reuse, the remaining solid catalyst was washed with centrifugal deionized water for several times until the eluent was neutral, and the centrifuged solid was dried for next reuse. The yield of 1,2-propanediol decreased from 32.5% to 31.6% after the second reuse, and decreased to 28.6% after the third reuse. The conversion rates of cellulose in the two cases were 96% and 92%, respectively. At the same time, the product distribution did not change significantly.

Claims (1)

1. a kind of method that catalytic hydrogenolysis cellulose produces propane diols, it is characterised in that comprise the following steps that：

（1）Catalyst synthesizes

（1.1）First take 0.15-0.25g phosphotungstic acids（H₃O₁₀W₁₂·12H₂O）It is soluble in water, solution is then slowly dropped to 1g β Molecular sieve gets on, ultrasonic 30min, stands aging 12h, then dries 4h at 110 DEG C, is then calcined 4h at 550 DEG C；

（1.2）Take the water nickel nitrates of 0.25-0.75g six（Ni(NO₃)₂·6H₂O）It is soluble in water, solution is then slowly dropped to step Suddenly（1.1）The material of synthesis gets on, ultrasonic 30min, stands aging 12h, then dries 4h at 110 DEG C, then in 550 DEG C of roastings 4h；

（1.3）By step（1.2）Resulting materials reduce 4h in 550 DEG C of hydrogen stream；Obtain Ni-W/ beta catalysts；

Wherein：The ratio that adds of Ni-W is 15:5-5:25；

（2）Catalytic reaction

Take step（1.3）The Ni-W/ beta catalysts of synthesis, cellulose and water are placed in the jar of Teflon, are subsequently placed in high temperature high In pressure reactor, in 210-240 DEG C of reaction temperature, reaction time 15-45min enters water-filling under conditions of reaction pressure 5-7MPa Thermal reduction reaction, cellulose aqueous solution is reduced to the small organic molecule mixed liquor based on propane diols, then purifies and separates, Obtain propane diols；Wherein：Catalyst amount is 5 mmol/L-15 mmol/L.