WO2014005251A1

WO2014005251A1 - Method for preparing isopropanol by catalytic conversion of cellulose

Info

Publication number: WO2014005251A1
Application number: PCT/CN2012/001155
Authority: WO
Inventors: 梁长海; 肖子辉; 徐彬; 王欢
Original assignee: 易高环保能源研究院有限公司; 大连理工大学
Priority date: 2012-07-04
Filing date: 2012-08-28
Publication date: 2014-01-09
Also published as: TW201402528A; CN102757310A; CN102757310B; TWI567050B

Abstract

Disclosed is a method for preparing isopropanol from cellulose, characterized by subjecting a cellulose to a catalytic reaction for the conversion into isopropanol in the presence of a copper chromite catalyst; wherein the copper chromite catalyst comprises a CuCr₂O₄ active phase or contains an active phase of a group consisting of CuO and Cr₂O₃; the weight ratio of cellulose to water is less than 15wt%; and the temperature of the catalytic reaction is 200°C to 270°C.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of producing isopropyl alcohol, and in particular to a method for producing isopropyl alcohol from cellulose. BACKGROUND OF THE INVENTION Isopropanol is an important chemical product and raw material, and is an excellent solvent which is miscible with ethanol, diethyl ether, chloroform and water. Isopropanol is also an intermediate in the synthesis of various organic compounds. It can be widely used in the fields of pharmaceuticals, cosmetics, plastics, perfumes, coatings, etc. Among them, paints and inks are the main application areas, accounting for about the total consumption of isopropanol. 50%. In addition, isopropanol can be dehydrated to obtain another important industrial product, propylene, which is in high demand for propylene. At present, the main method for producing isopropyl alcohol is propylene hydration. According to whether or not intermediate products are produced, it can be further divided into propylene indirect hydration and direct propylene hydration. However, since propylene can be used to produce polypropylene, phenol, acetone, butanol, octanol, acrylonitrile, propylene acrylate, acrylic acid, and isopropanol, the demand for propylene is extremely high, which inevitably leads to propylene resources. shortage. Therefore, there is still a need to develop other processes for producing isopropanol, particularly materials other than propylene. Cellulose is the most abundant renewable resource on the planet, with abundant sources, such as straw remaining in agricultural production, waste from forestry production, and so on. Therefore, it is very important to make full use of cheap cellulose to convert into high-value chemicals. Compared with other renewable resources, since cellulose can not be eaten, the process of biomass energy conversion can be minimized, which may have adverse effects on human food security. Since cellulose has a molecular bond and an intramolecular hydrogen bond, it has a very stable structure. In the prior art, cellulose is first hydrolyzed to glucose using an acid as a catalyst, and then hydrogenolyzed to other chemicals. In the process of catalytic conversion of cellulose to polyol, most of the noble metal catalysts supported by molecular sieves are used, the cost of such catalysts is high, and the product selection rate is not easy to control. Cellulose has been catalyzed by a nickel-tungsten (Ni-W) catalyst, but the main product is ethylene glycol. For example, reference can be made to Chinese patents CN 101723802, CN101735014A and the like. There is currently no prior art technology for the preparation of isopropanol-based products from cellulose catalysis. In other prior art techniques for the catalytic conversion of cellulose, in order to increase the conversion rate and the yield of the target product, some mineral acid is also added to the reaction system, thereby generating a large amount of wastewater. Also, since the acid is added, the requirements for the reaction equipment are also increased. Other prior art techniques have shown that prior to the catalytic conversion step, the cellulose must undergo several pre-treatments to achieve better catalytic effects, such as mechanical ball milling, chopping, beating, sodium hydroxide solution or liquid ammonia. Rational, iontophoretic radiation, microwave sonication, steam explosion, etc., to reduce the crystallinity of cellulose and improve the reactivity of cellulose. These cumbersome pre-processing increases manufacturing costs and are not conducive to industrial applications. In addition to the aforementioned difficulties in the addition and pretreatment of the acid, many literatures and patents have shown that in the catalytic process, the mass ratio of cellulose to water cannot be increased, the reaction concentration is low, and the requirements for product separation and purification are both Very high. Especially in the case of high cellulose to water mass ratio, coking phenomenon is easy to occur, which greatly affects the progress of catalytic conversion, and is not conducive to the operation and management of equipment. SUMMARY OF THE INVENTION The present invention provides a process for producing isopropanol from cellulose, characterized in that a relatively pure cellulose raw material is subjected to a one-step catalytic reaction in the presence of a copper chromium catalyst to be converted into isopropanol. A relatively pure cellulose raw material means a raw material having a cellulose content of more than 85 wt%. The main sources of cellulose are hemp, wheat straw, straw, bagasse and the like. The main impurities are hemicellulose, lignin and some mineral salts. Therefore, a large amount of impurities will affect the catalytic activity and the yield of the target product. Generally, a purification pretreatment process is required, and the purity can reach 85% or more. The purification process can be carried out. See "Dyeing and Finishing Technology, 2011, 33, 12-16". With the copper-chromium catalyst provided by the present invention, cellulose can be directly catalytically converted into isopropanol in one step, and the copper-chromium catalyst has excellent isopropanol selectivity. The reaction pathway for the catalytic conversion of cellulose using a copper chromium catalyst is as follows. First, the cellulose is hydrolyzed to glucose, and then the glucose is hydrogenated to form sorbitol, which is then hydrogenolyzed to form a product including isopropanol. The conversion of the present invention can be accomplished "in one step", that is, the above-mentioned "hydrolysis-hydrogenation-hydrogenolysis" reaction can be carried out in a single reaction step in an actual industrial system.

In one embodiment, the copper-chromium catalyst comprises a CuCr ₂ 0 ₄ active phase, or an active phase comprising a C _U Cr ₂ 0 ₄ active phase and a group of CuO and Cr ₂ 0 ₃ For example, a structure of CuCr ₂ 0 _{4 ,} a structure of CuCr ₂ 0 ₄ /CuO, a structure of CuC _{r 2} 0 ₄ /Cr ₂ 0 ₃ , etc., wherein a molar ratio of copper to chromium is 0.25 or more, for example, Cu /Cr The molar ratio is 0.3, 0.5, 1, 1.5, 2, 2.5, 4, 5, 6, 8, and the like. In a preferred embodiment, the Cu/Cr molar ratio is 0.5 or more. Compared to the prior art, the process of the present invention can be catalyzed at a higher cellulose to water mass ratio (water as medium, cellulose mass/water quality). In some embodiments, the mass ratio of cellulose to water is from 0.1 to 10 wt% and can be up to 15 wt%. In one embodiment, the temperature of the catalytic reaction is from 200 ° C or more to 270 Å or less, preferably from 220 ° C or more to 260 ° C or less. The medium for the catalytic reaction according to the invention may be water. In one embodiment, a raw material comprising cellulose having a mass ratio of cellulose to water of 15% or less is used in an environment of water, 200 to 27 (at a reaction temperature of TC, including CuCr ₂ 0 _A one-step catalytic conversion to isopropanol in the presence of a copper-chromium catalyst having an active phase and a copper/chromium molar ratio of 0.25 or more. In a preferred embodiment, the mass ratio of cellulose to water is 0.1- 10 wt% of cellulose raw material, in a water-based environment, a reaction temperature of 220 Ό to 260 Torr and a reaction pressure of 5-8 MPa, one-step catalytic conversion to isopropanol by a copper chromium catalyst; The copper chromium catalyst comprises a structure of CuC _{r 2} 0 ₄ /CuO, and the copper/chromium molar ratio is 0.5 or more. In a preferred embodiment, the yield of isopropanol obtained according to the method of the present invention is used for catalysis. The total weight of the cellulose to be reacted can be up to 25% or more, usually up to 45% or more. In a more preferred embodiment, the yield of isopropanol is more than 50%, for example, more than 55%, more than 60%, 65% or more, 70% or more, 80% or more, etc. The present invention provides a fiber from fiber The technique of directly converting catalytically to isopropyl alcohol in one step, using water as a medium, without adding an additive such as an acid, and catalytically converting with a copper-chromium catalyst, can achieve good activity and selectivity. With the technology of the present invention, It can catalyze at a high cellulose to water mass ratio and effectively prevent coking, and even if the cellulose is not pretreated, it can achieve better results. The technology of the present invention is both green and simple Achieving a higher yield of isopropanol, which is very suitable for industrial mass production. The method according to the invention can achieve a conversion rate of cellulose of more than 30%, usually up to 50% or more. In some embodiments, The set reaction parameters, the conversion of cellulose is more than 60%, preferably more than 80%, more preferably more than 90% or even 100%. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows X-ray diffraction of a copper-chromium catalyst ( XRD). DETAILED DESCRIPTION OF THE INVENTION 1. Preparation of Copper Chromium Catalyst The preparation of the catalyst in this example can be referred to C. Liang, Z. et al., Catal. Lett. (2009), 130, 169-176; Z. Ma et al" J. Mater. Chem. (2010), 20, 755-760; and Z. Xiao et al., Ind. Eng. Chem. Res. (2011), 50, 2031-2039, The invention is hereby incorporated by reference in its entirety. The following methods can be used: (1) Sol-gel method

Prepare an ethanol solution of Cr (Ν0 ₃ ) 3·9Η ₂ 0 and Cu (Ν0 ₃ ) ₂ ·3Η ₂₀ (the mass concentration of metal is 0.3 g/ml (g/mL)), and control the metal Cu/Cr molar ratio to 0.25, 0.5, 1, 2 and 4. At 60 ° C, 18 mL of glycopropene was added with stirring to obtain a gel. After drying overnight at 85 ° C, it was calcined in an air atmosphere at 500 ° C for 2 hours (h) to obtain a copper chromium catalyst.

(2) Carbon template method

Prepare a mixed solution of Cr (Ν0 ₃ ) ₃ ·9Η ₂ 0 and Cu (Ν0 ₃ ) ₂ ·3Η ₂ 0 in ethanol and water, control the metal Cu/Cr molar ratio to 0.5, and immerse in a high volume table at room temperature. On activated carbon. After drying overnight at 85 ° C, it was calcined in an air atmosphere at 500 ° C for 2 hours to obtain a copper chromium catalyst.

(3) Commercial catalysts

The commercial copper chromium catalyst was purchased from Southern Chemical. The catalyst was columnar and needed to be ground into a powder before use. For the copper chromium catalysts employed in the present invention, preparation at different Cu/Cr molar ratios affects the crystalline phase of the catalyst. Furthermore, the formation of the active phase CuCr ₂ 0 ₄ is also of considerable importance for the copper-chromium catalyst, since the active phase C _U Cr ₂ 0 ₄ relatively achieves a higher cellulose conversion and isopropanol yield. Fig. 1 shows an X-ray diffraction (XRD) pattern of a copper-chromium catalyst prepared by a sol-gel method. The results show that the Cu-Cr catalysts listed in Table 1 can form an active phase CuCr ₂ 0 _{4 in} addition to the catalyst obtained by calcination at 30 CTC. Table 1. Crystallographic phases of catalysts prepared at different Cu/Cr molar ratios

Cu/Cr molar ratio

0.25 CuCr ₂ 0 ₄ , Cr ₂ 0 ₃

0.5 CuCr ₂ 0 ₄

1 CuCr ₂ 0 ₄ , CuO

2 CuCr ₂ 0 ₄ , CuO

4 CuCr ₂ 0 ₄ , CuO

4 ^a CuO, Cr ₂ 0 ₃

The catalyst used in the term had a calcination temperature of 30 (TC, and the others were 500 Torr.

2. Catalytic reaction on cellulose Before the catalytic reaction, the copper chromium catalyst was first reduced under hydrogen gas at 300 Torr for 2 hours. In one embodiment, cellulose (eg, cellulose available from Belling Chemical, model Avicd pH-101) and a quantity of water are added to a 50 mL autoclave for reaction, the reaction atmosphere is hydrogen, and the reaction pressure is controlled at Between 4-8 MPa, the temperature range is 200-270 ° C, and the mass ratio of cellulose to water is selected to be 15 wt% or less. The product obtained by the catalytic reaction is mainly a liquid phase product, and the gas phase products (such as CH ₄ , C ₂ H ₄ , C0 _{2 ,} etc.) are few. The obtained liquid phase product is analyzed, and the conversion rate and yield are calculated, and the calculation formula is - conversion rate (%) = converted cellulose mass / initial cellulose total mass X 100%

Yield (%) = product quality / initial cellulose total mass X 100%. The inventors tested the effects of various parameter conditions on the catalytic reaction. (1) Effect of Cu/Cr molar ratio on catalytic reaction The test was carried out by the above various preparation methods, sources, Cu/Cr molar ratio copper chromium catalyst. The reaction conditions were as follows: mass ratio of cellulose to water was 1 wt%, catalyst was 0.3 g, reaction pressure was 6 MPa, reaction temperature was 220 ° C, stirring speed was 900 rpm, and reaction time was 0.5 h. The results are shown in Table 2. Table 2. Effect of Cu/Cr molar ratio on catalytic reaction

Cu/Cr cellulose yield (%)

Molar ratio conversion (%) isopropanol ethylene glycol 1,2-propanediol sorbitol other ^a

0.25 52.1 16.8 3.3 4.2 17.5 10.3

0.5 64.2 25.1 4.2 5.9 18.1 10.9

29.6

0.5 ^b 60.2 1.1 11.3 10.7 7.5

(glycerol 14.3 )

18.0

0.5 ^C 65.1 10.4 9.6 13.5 13.6

(glycerol 9.1)

1 71.9 33.6 3.1 5.6 16.2 13.4

2 80.2 53.5 2.7 4.1 11.4 8.5

4 91.1 61.9 0.2 1.8 10.1 17.4

4 ^d 20.4 3.4 1.6 8.9 2.1 Section 4.4 contains some liquid phase products and gas phase products whose composition cannot be determined.

The b-term uses a commercial copper-chromium catalyst, the ^e- term uses a copper-chromium catalyst prepared by a carbon template method, the other is a copper-chromium catalyst prepared by a sol-gel method, and the ^d -th is a catalyst calcined at 300 °C. Comparing the above three copper-chromium catalysts, in the case of the same Cu/Cr molar ratio, the catalyst prepared by the sol-gel method and the catalyst prepared by the carbon template method have comparable conversion rates to cellulose (64.2% and 65.1%). However, the isopropyl alcohol yield of the catalyst prepared by the sol-gel method is significantly higher. Catalysts prepared by the carbon template method have a wide distribution of selectivity to products. The commercial copper-chromium catalyst has a slightly poorer activity on cellulose conversion, about 60.2%, and the obtained products are mainly glycerin, 1,2-propanediol and ethylene glycol. The yields of the three are similar, but the selectivity to isopropanol Very poor, only 1.1%. For copper-chromium catalysts with the same Cu/Cr molar ratio, the difference in these catalytic reactions may be attributed to some physicochemical properties of the catalyst. Changes such as specific surface area, surface species and other factors. Further, as shown in Table 2, for the copper-chromium catalyst prepared by the sol-gel method, as the Cu/Cr molar ratio increases, the conversion of cellulose increases, and the yield of isopropanol increases, and this result is related to Cu- The structure of the Cr catalyst is related. Referring to Table 1 and the predominant crystalline phase catalytic reaction results in Table 2, when the Cu / Cr molar ratio less than the stoichiometric formed CuCr ₂ 0 ₄ ratio 0.5, _₂₀₄ formed of Cr structure of a CuCr / ₂ 0 ₃ and had The conversion rate of cellulose can be more than 50%, and isopropanol and sorbitol are the main products; when the ratio is more than 0.5, the structure of CuC C CuO is formed, wherein the formation of CuCr ₂ 0 ₄ can increase copper. The dispersion degree of the chromium catalyst makes the copper derived from C _U Cr ₂ 0 ₄ have higher catalytic activity, and when the total amount of the catalyst is the same, the molar ratio of Cu/Cr increases so that the content of active copper also increases, in the reaction time. The conversion rate of cellulose has reached 60% or more, even more than 90%, in 0.5 hours, and the selectivity of isopropyl alcohol has also increased significantly, reaching 25%-62%. For the catalyst which did not form the active phase C _U Cr ₂ 04, a lower cellulose conversion and a yield of isopropanol were shown. Table 2 confirms that the structure of CuC O CuO is more favorable for the progress of the catalytic reaction and the selectivity of the target product isopropanol. At the same time, the formation of the active phase CuCr ₂ 0 ₄ can significantly increase the activity of the catalyst. (2) Effect of reaction temperature on catalytic reaction Catalytic reaction was carried out by a copper-chromium catalyst (Cu/Cr=4) prepared by a sol-gel method. The reaction conditions were as follows: mass ratio of cellulose to water was 1 wt%, catalyst was 0.3 g, reaction pressure was 6 MPa, stirring speed was 900 rpm, and reaction time was 0.5 h. The results are shown in Table 3. Table 3. Effect of reaction temperature on catalytic reaction

Reaction temperature cellulose yield (%)

( °C ) Conversion (%) Isopropanol Ethylene glycol 1,2-propanediol Sorbitol Others a

200 32.5 11.6 0.5 0.3 1.6 18.5

220 91.1 61.9 0.2 1.8 10.1 17.1

245 100 68.1 7.1 4.6 16.0 4.2

260 100 70.2 12.3 5.1 3.4 9.0

270 100 40.3 14.3 14.7 2.8 27.9 Contains some liquid phase products and gas phase products whose composition cannot be determined. As shown in Table 3, as the reaction temperature increases, the cellulose conversion rate also increases rapidly. When the reaction temperature is increased from 20 (TC to 220 ,, the cellulose conversion rate immediately jumps to over 90%, and when the reaction temperature is above 240 ° C, the conversion rate is 100%. In general, the yield of isopropanol is also It increases with increasing temperature, but the reaction temperature exceeds 260 Ό, and the yield of isopropanol begins to decrease. Since the high temperature favors cellulose hydrolysis and subsequent hydrogenolysis, it rises with temperature in the appropriate temperature range. High, cellulose conversion, isopropanol and sorbitol yields increased significantly. However, when the temperature rises to a certain level (245 °C), cellulose hydrolysis tends to be complete; if the temperature continues to rise (260 ° C) , which makes the hydrogenolysis of sorbitol especially obvious, that is, sorbitol continues to hydrogenate into other small molecule products to reduce the yield, but at this time, it is isopropyl The alcohol has a low impact and it still maintains a fairly good yield. If the temperature is further increased (270 ° C), the isopropanol will further hydrolyze into other gas phase products at a high temperature, so that the yield of isopropanol is lowered at a reaction temperature of 270 ° C, and the yield of other unknown products is Significant improvement.

(3) Effect of reaction pressure on catalytic reaction The copper-chromium catalyst (Cu/Cr=4) prepared by sol-gel method was used for catalytic reaction. The reaction conditions were as follows: mass ratio of cellulose to water l wt%, catalyst 0.3 g, reaction temperature 220 ° C, stirring speed 900 rpm, reaction time 0.5 h. The results are shown in Table 4. Table 4. Effect of reaction pressure on catalytic reaction

Reaction pressure cellulose yield (%)

(MPa) Conversion (%) Isopropanol Ethylene glycol 1,2-propanediol Sorbitol Others a

4 42.1 20.5 2.2 4.9 7.8 6.7

5 79.6 53.4 1.6 3.4 9.6 11.6

6 91.1 61.9 0.2 1.8 10.1 17.1

7 100 63.2 7.3 6.4 12.4 10.7

8 100 60.1 8.9 8.4 8.3 14.3 Contains some liquid phase products and gas phase products whose composition cannot be determined. As shown in Table 4, when the hydrogen pressure is increased, the cellulose conversion rate is increased, and the yield of the target product isopropanol is It increases rapidly first and then stabilizes. In addition, observing the yield of sorbitol shows a parabolic trend. Obviously, increasing the reaction pressure is beneficial to cellulose conversion, but further increasing the reaction pressure enhances the hydrogenolysis of sorbitol and lowers the yield of sorbitol. The yield of ethylene glycol and 1,2-propanediol is increased. When the reaction pressure reaches 8 MPa, isopropanol may undergo subsequent hydrogenolysis, resulting in a slight decrease in yield, but overall, the effect of the reaction pressure on the subsequent hydrogenolysis of isopropanol has no effect on the reaction temperature.

(4) Effect of reaction time on catalytic reaction Catalytic reaction was carried out by a copper-chromium catalyst (Cu/Cr=4) prepared by a sol-gel method. The reaction conditions were as follows: mass ratio of cellulose to water was 1 wt%, catalyst was 0.3 g, reaction temperature was 220 ° C, reaction pressure was 6 MPa, and stirring speed was 900 rpm. The results are shown in Table 5.

Quality and

Water quantity dimension

Table 5. Effect of reaction time on catalytic reaction

Reaction time cellulose yield (%)

(h) Conversion (%) isopropanol ethylene glycol 1,2-propanediol sorbitol other a

0.25 50.5 34.2 0.3 1.2 7.8 7.0

0.5 91.1 61.9 0.2 1.8 10.1 17.1

1 100 62.4 2.4 3.7 11.6 19.9

2 100 62.6 4.3 3.4 8.4 21.3

4 100 60.4 3.5 4.6 7.9 23.6 Contains some liquid phase products and gas phase products whose composition cannot be determined. The reaction time of 100% can be achieved when the reaction time is 1 hour, and the yield of isopropanol can be 0.5 hours in the reaction time. Stabilization is achieved, and a slight drop begins in 4 hours. It should be caused by a long-term reaction condition that causes a higher probability of subsequent hydrogenolysis. Observing the yield of sorbitol also shows the same trend.

(5) Effect of mass ratio of cellulose to water on catalytic reaction Catalytic reaction was carried out by a copper-chromium catalyst (Cu/Cr=4) prepared by a sol-gel method. The reaction conditions were as follows: catalyst 0.3 g, reaction temperature 220 Torr, reaction pressure 6 MPa, stirring speed 900 rpm, and reaction times of 0.5 h and 5 h, respectively. The results are shown in Table 6. Table 6. Effect of mass ratio of cellulose to water on catalytic reaction

Reaction yield (%)

Time one

Conversion rate 1 2 6 P two

Ratio (h) . _0/ . Isopropanol hexanediol ''diisosorbitol sorbitol other ¹

(% alcohol

(wt%) ^

3 0.5 60.6 15.1 5.7 8.5 1.9 10.7 18.7

6 0.5 49.8 10.2 4.5 4.1 1.6 12.6 16.8

10 0.5 33.4 9.1 3.4 3.2 1.2 8.1 8.4

15 0.5 29.6 8.4 5.6 2.6 1.4 9.3 2.3

3 5 100 6.2 14.9 19.5 4.1 21.3 34.0

6 5 100 5.3 13.8 18.7 4.7 25.8 31.7

10 5 95.6 5.0 15.5 14.6 6.8 27.0 31.1 3 contains some liquid phase products and gas phase products whose composition cannot be determined. As shown in Table 6, the mass ratio of cellulose to water has a significant effect on the catalytic reaction. When the mass ratio of cellulose to water increases, the conversion of cellulose decreases, and the yield of isopropanol decreases slowly, which may be related to the adsorption equilibrium and mass transfer of reactants and products on the catalyst. The cellulose covers the active site, and the resulting product cannot be effectively desorbed from the active site, resulting in a decrease in the conversion rate. Prolonging the reaction time, it was found that only the conversion of cellulose was increased, but the yield of isopropanol was not improved. As mentioned above, the prolonged time caused subsequent hydrogenolysis of isopropanol. Under the condition of high cellulose to water mass ratio, high-carbon polyols such as isosorbide, hexanediol and hexanetriol are produced, which further explains the problem of competitive adsorption of the product. The catalyst does not have enough active sites to hydrogenate sorbitol. It is a low carbon polyol. In addition, under this experimental condition, even if the mass ratio of cellulose to water is increased to 15 wt%, no coking phenomenon occurs, indicating that the copper-chromium catalyst is excellent in preventing high-mass ratio hydrogenolysis of cellulose and water. The phenomenon of coking during the process.

(6) Effect of high cellulose to water mass ratio on catalytic reaction The copper chromium catalyst (Cu/Cr=4) prepared by sol-gel method was used for catalytic reaction. The reaction conditions were as follows: mass ratio of cellulose to water was 10 wt%, catalyst was 0.3 g, reaction temperature was 220 ° C, reaction pressure was 6 MPa, and stirring speed was 900 rpm. The results are shown in Table 7. Table 7. Effect of reaction time on catalytic reaction

Reaction time cellulose yield (%)

(h) conversion rate (%) isopropanol hexanediol 1,2,6-hexanetriol isosorbide sorbitol other a

0.5 33.4 15.1 3.4 3.2 1.2 8.1 2.4

1 56.2 11.5 4.1 5.8 2.5 12.0 20.3

2 76.8 8.2 7.6 11.4 4.1 18.1 27.4

5 95.6 5.0 15.5 14.6 6.8 27.0 26.7

8 98.6 4.4 13.8 16.3 7.1 15.6 41.4

23 100 4.0 13.9 17.7 7.2 10.1 47.1 Contains some liquid phase products and gas phase products whose composition cannot be determined. Under the condition of 10wt% high cellulose to water mass ratio, the reaction time has an effect on the catalytic reaction, similar to the use of low fiber. The ratio of prime to water. Overall, the cellulose conversion rate increases with time, but the yield of isopropanol decreases. Obviously, under the condition of high cellulose to water mass ratio, prolonging the reaction time is more favorable for isopropanol and sorbitol. Subsequent hydrogenolysis causes an increase in the yield of other products. The invention develops a new process route for producing isopropanol from biomass for the first time, and can directly convert acyl alcohol into isopropyl alcohol from one step of cellulose, without adding additional additives such as acid, so the equipment requirements are not high, nor will it A large amount of wastewater is produced in the process. Moreover, the copper-chromium catalyst of the invention can achieve good activity and selectivity, and the preparation process is simple and the price is low. With the technology of the present invention, the production conditions are relatively mild, the energy consumption is low, and the catalyst can be catalyzed at a high cellulose to water mass ratio, and the coking phenomenon is effectively prevented. The direct catalytic conversion of cellulose to isopropanol in one step solves the problem of the shortage of raw materials for hydration of propylene from propylene. At the same time, the isopropanol obtained by the method of the invention can be dehydrated to form propylene, but can be used as propylene. Source, effectively compensate for the current situation of the propylene market in short supply. In general, the technology of the present invention is both green and simple, and can achieve a high yield of isopropanol, and is extremely suitable for industrial mass production. The invention and its several embodiments have been described above by way of illustration and not limitation. Those skilled in the art will recognize other alternative embodiments after reading this specification, and such embodiments are also within the scope of the invention.

Claims

Rights request

1. A method for preparing isopropyl alcohol from cellulose, characterized in that: in the presence of a copper-chromium catalyst, cellulose is subjected to a catalytic reaction to convert into isopropyl alcohol.

2. The method according to claim 1, wherein the conversion is completed in a single industrial reaction step.

3. The method according to claim 1, wherein the copper-chromium catalyst includes CuCr ₂ 0 ₄ active phase.

4. The method according to claim 1, wherein the copper-chromium catalyst includes an active phase of CuO or Cr ₂ 0 ₃ .

5. The method according to any one of claims 1-4, wherein the copper-chromium catalyst is prepared by a sol-gel method.

6. The method according to any one of claims 1-4, characterized in that there is no acid additive in the catalytic reaction.

7. The method according to any one of claims 1 to 4, wherein the molar ratio of copper/chromium in the copper-chromium catalyst is above 0.25.

8. The method according to claim 7, wherein the molar ratio of copper/chromium in the copper-chromium catalyst is above 0.5.

9. The method according to any one of claims 1-4, wherein the medium for the catalytic reaction is water.

10. The method according to claim 9, wherein the mass ratio of cellulose to water is less than 15 wt%.

11. The method according to claim 10, wherein the mass ratio of cellulose to water is 0.1-10 wt%.

12. The method according to any one of claims 1-4, wherein the temperature of the catalytic reaction is 200°C to 270°C.

13. The method according to claim 12, wherein the temperature of the catalytic reaction is 220°C to 260°C.

14. The method according to any one of claims 1-4, wherein the pressure of the catalytic reaction is 5 to 8 MPa.

15. A method for producing isopropyl alcohol from cellulose, characterized by: using water as the medium, the mass ratio of cellulose to water is 0.1-10 wt%, the reaction temperature is 220°C to 260°C, and the pressure is Under the reaction conditions of 5-8 MPa, the copper-chromium catalyst is used to catalyze the conversion into isopropyl alcohol in one step; wherein the copper-chromium catalyst includes a structure of CuC _r2 0 ₄ /CuO, and copper/chromium The molar ratio is above 0.5.

16. The method according to claim 15, wherein the copper-chromium catalyst is prepared by a sol-gel method.