WO2013086871A1 - Method for preparing glycolaldehyde from glycerin - Google Patents

Abstract

The present invention provides a new method for preparing glycolaldehyde with glycerin as a raw material. By using an optical-thermal coupling method, with TiO₂ that supports a metal promoter as a catalyst, glycerin is further converted to glycolaldehyde, formic acid, and hydrogen in an aqueous solution. By adopting the glycerin conversion method in the present invention, glycolaldehyde can be prepared with high selectivity; the selectivity may be up to 80% and more, and the yield is up to 35% and more. The reaction condition is mild; no acid, alkali or organic solution needs to be added; the reaction does not require a high temperature or a high pressure. The present invention provides a new approach for preparing glycolaldehyde, which is cheap and green.

Description

 Method for preparing glycolaldehyde by using glycerol

The invention relates to a novel method for preparing glycolaldehyde from glycerol. The present invention particularly relates to 1) under conditions of light and heat, further reaction process to convert glycerol into glycolaldehyde; 2) preparing respective Ti0 and ₂ photocatalyst. Background technique

 The current two major problems of resources and environment have greatly promoted the research on renewable biomass energy, including oil, starch, cellulose, hemicellulose and lignin. As a result, developed industrial countries have developed corresponding biomass utilization programs, meaning that the fuel and chemical industries are from non-renewable "hydrocarbons."

(Hydrocarbons) "The era is moving toward renewable "carbonhydrates". For example, the United States expects to receive more than 20% of liquid fuels and more than 25% of organic chemicals from biomass resources by 2030 (Talysis Today, 2006, 111, 119-132. ).

 Glycerol is the smallest polyol that can be obtained from biomass. Glycerol is a by-product of the preparation of biodiesel by transesterification of triglycerides rich in oils and fats of plants or animals. As the demand for biodiesel increases, its output has increased significantly year by year. In 2010, worldwide glycerin exceeded 120 million tons, resulting in a large excess of by-product glycerin. Therefore, the preparation of high value-added chemicals and clean fuels from inexpensive glycerol has received great attention.

At present, the use of glycerol to prepare high value-added chemicals mainly uses the following techniques: (I) Selective oxidation (chemical selective oxidation and electrocatalytic selective oxidation): wherein chemical selective oxidation mainly uses hydrogen peroxide, oxygen or air. As an oxidizing agent, glycerin is selectively converted into a product such as dihydroxyacetone or glyceric acid. Representative systems are mainly: (1) Hutchings et al. use 1% Au/graphene as a catalyst (Chem. Commun., 2002, 696-697.), in NaOH solution, under milder conditions (oxygen partial pressure) Catalytic oxidation of glycerol at 0.3 - 0.6 MPa, temperature 333 K, reaction for 3 h, and water as solvent. The conversion of glycerol was 72% and the selectivity of glyceric acid was reduced by 86%. (2) The Prati research team found that glycerol can be converted to glycerol in one step with 1% AuPt (6:4) / hydrogenated mordenite as an catalyst in an acidic solution. The selectivity is as high as 83% at 70% conversion (Angew. Chem Int. Ed., 2010, 49, 4499 -4502.), the method mainly uses noble metals Au, Pt, etc. as catalysts, and the loading on the carrier is as high as 1% to 5%, which makes the production cost high. Dihydroxyacetone was prepared under alkaline conditions using AuPt/activated carbon as a catalyst. The selectivity of dihydroxyacetone was about 36% (Appl. Tal, B, 2007, 70, 637-643.). (3) Electrocatalytic selective oxidation: Glycerol can form glyceric acid or dihydroxyacetone by oxidation reaction at the anode of the silver electrode. The catalyst for electrocatalytic oxidation of glycerol is mainly organic acyl-2,2,6,6-tetramethylpiperidine-1-hydroxy (TEMPO group compound) due to its better selectivity and higher catalytic activity and oxidant used. The diversity of this catalyst can oxidize alcohol compounds to carbonylated or carboxyl compounds. Ciriminn et al. used a one-pot method with TEMPO-based bromine as a catalyst and NaOCl as an oxidant at 275 K, ρΗ. In water with =10, when TEMPO-doped microporous water glass was used as a catalyst, 6.5 mol% TEMPO was added to the solution. After 30 min, pyruvic acid production began in the product. When the conversion of glycerol is 100%, the selectivity of pyruvic acid is 98% (Adv. Synth. Tal, 2003, 345, 383-388.). The recovery of the oxidant NaOCl in this process is difficult. (Π) Selective hydrogenolysis: This method is a hydrogenolysis reaction of glycerol in the presence of H ₂ under the action of a catalyst to obtain 1,2-propanediol, 1, 3-propanediol and ethylene glycol. Dasari et al. used copper chromite as a catalyst to hydrogenate 80% aqueous glycerol solution to a temperature of 200 V and a hydrogen pressure of 1.4 MPa to produce 1,2-propanediol with a selectivity of 85% and a yield of 46.6%. (Appl. Tal. A: Gen., 2005, 281: 225-231.). In 2000, Shell developed a method for the synthesis of 1, 3-propanediol by catalyzing the hydrogenolysis of glycerol using a homogeneous system (US 6080898). The method uses a complex containing a platinum-based metal (such as Pd or Pt) as a catalyst, and adds methanesulfonic acid or trifluoromethanesulfonic acid as an additive. Under water or sulfolane as a solvent, glycerol is hydrogenolyzed to form 1, 3-propanediol, which has a selectivity of up to 30.8%, but also produces toxic acrolein. However, the hydrogenolysis process requires a large amount of valuable hydrogen as a raw material and requires harsh reaction conditions. (ΠΙ) Dehydration reaction: The main technique is the dehydration of glycerol to produce acrolein under peracid catalysis and supercritical water conditions. Bijhle et al. used a pressurized hot water device with a reaction temperature of 573-747 K, a pressure of 25-45 MP, a residence time of 16-100 s, an aqueous solution conversion of glycerol of 31%, and a selectivity of 37% (J. Supercrit. Fluids, 2002, 22, 37-53. ). Watanabe et al. found that the addition of 3⁄4S0 _{4 to} aqueous glycerol increased the yield of acrolein. Under supercritical water conditions (673 K and 34.5 MPa), when the conversion of glycerol is 90%, the selectivity of acrolein is about 80% (Bioresour. Techno 1., 2007, 98, 1285-1290.). The method has severe reaction conditions and requires high reaction equipment.

The invention uses glycerol as a raw material, under the anaerobic condition, uses a photo-thermal coupling method to carry a very small amount of metal promoter Ti0 ₂ as a catalyst, and converts glycerol into glycolaldehyde in one step in an aqueous solution, and simultaneously obtains formic acid and 3⁄4.

 Glycolaldehyde is an important pharmaceutical raw material and can be used as an intermediate for the synthesis of D,L-serine. Hydrogenation of glycolaldehyde is a promising method for preparing bulk chemical glycols. At present, glycolaldehyde is mainly prepared from ethylene glycol or dihydroxymaleic acid as raw materials, but these synthetic routes are expensive and are not suitable for large-scale production. Summary of the invention

 It is an object of the present invention to provide a novel route for the conversion of glycerol to glycolaldehyde by photo-thermal methods; a further object of the present invention is to provide a process for the preparation of a catalyst using the above process.

A process of preparing glycolaldehyde glycerol utilization, use of the co-catalyst supported photocatalyst Ti0 _2, using the light - heat coupling method, in water, under anaerobic conditions, the reaction by-step conversion of glycerol to ethanol aldehyde, carboxylic acid And 3⁄4;

 The heat in the photo-thermal coupling method means that the reaction temperature of the reaction system is 20-150 ° C; in water, the concentration of the raw material glycerin aqueous solution is 0.1-40%. The amount of the catalyst added in 100 ml of the aqueous glycerin solution is 0.04 - 0.2 g.

This reaction is accompanied by the formation of glyceraldehyde, formic acid, C0 ₂ , and a small amount of CO and traces of CH ₄ .

The reaction formula is as follows: CH ₂ OH-CH ₂ OH-CH ₂ OH + H ₂ 0 → CH ₂ OH-CHO + 2H ₂ + HCOOH. The light source used in the photo-thermal coupling method includes a xenon lamp, a mercury lamp, a barium mercury lamp, a tungsten iodine lamp or sunlight, and the wavelength of the light is optimally in the range of 190 to 400 nm. Heat source: Additional auxiliary heating equipment can be used, or it can be directly heated by the heat generated by the light source.

 The reaction to an anaerobic condition means that the vacuuming method or the inert gas excludes the air in the reaction vessel, and the inert gas is nitrogen, helium or argon.

The promoter-supporting Ti0 ₂ refers to a supported cocatalyst active component on Ti0 ₂ , one or more of the promoter active components Pt, R, Pd, Au, Ir, Cu, Ni, and the cocatalyst loading The amount is 0.01 to 5.0% by weight of Ti0 ₂ .

The present invention is preparation step Ti0 ₂ photocatalyst supported cocatalyst are as follows:

1. Synthesis of Ti0 ₂ :

A suitable titanium source and a different volume (0.5-20 mL) of inorganic acid are mixed, and an anatase, anatase-containing and rutile mixed crystal phase is prepared at a reaction temperature of 120-200 ° C for 6-48 ho. Ti0 _{2 of} rutile phase (J. Cryst. Growth, 2009, 312: 79-85).

 The titanium source used therein includes tetrabutyl titanate, titanium isopropoxide, titanium tetrachloride, titanium tetrafluoride, titanium sulfate, preferably titanium isopropoxide. The acid to be used includes hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid, phosphoric acid, preferably hydrochloric acid.

 2. Co-catalyst loading:

The surface of the photocatalyst Ti0 ₂ is loaded with 0.01-5.0% by mass of a metal as a cocatalyst by in situ photoreduction deposition (J Am Chem Soc, 1978, 100: 4317-4318) or immersion reduction (J Catal, 1998). , 178: 34-48) method loading, preferably in situ photoreduction deposition.

Ti0 ₂ carried a precious metal catalyst according to the present invention, light, Ti0 _2, a co-catalyst comprising a titanium dioxide product (P25) and the hydrothermal synthesis comprises a metal R, Pt, Pd, Au, Ir, Ni, Cu.

Specifically: adding Ti0 ₂ to the soluble precursor solution of the active component of the promoter, 0.00 lmg-lmg/L (H ₂ PtCl6-6H ₂ 0, PdCl ₂ , H ₂ AuCl ₆ 6H ₂ 0, H ₂ IrCl6-6H ₂ 0, In Cu(N0 ₃ ) ₂ , Ni(N0 ₃ ) ₂ ), after photo-reduction or immersion drying of Ti0 ₂ into a soluble precursor solution (1-10 mL) of the active component of the promoter, hydrogen is reduced at 300 ° C. 2 hours.

The synthesis method of the catalyst of the invention is simple, easy to control and reproducible. Among them, the rutile phase Ti0 ₂ using titanium isopropoxide as a raw material exhibits good catalytic activity in the reaction and has high selectivity to glycolaldehyde.

 The present invention has the following advantages over known glycerol conversion techniques:

1. In the present invention, high-quality glycolaldehyde is prepared in one step from glycerol, which is different from the products converted from glycerol in the literature. A clean, high combustion value of H ₂ can be prepared simultaneously in the reaction.

 2. An aqueous solution of glycerin is used in the present invention, and no additional addition of an acid, a base, or an organic solvent is required.

3. The photocatalyst used in the present invention is non-toxic and inexpensive Ti0 ₂ , and the catalyst is easy to be separated and recovered, and can be reused;

4. The process has the potential to directly use sunlight as a light-heat source. No additional energy consumption is required. DRAWINGS Figure 1 is a mass spectrum of glycolaldehyde;

Figure 2 is an X-ray powder diffraction pattern Ti0 and ₂ photocatalyst. In the present invention, T1 is mainly an anatase phase, T2 and T4 are mixed crystal phases, and T3 and T5 are rutile phases. detailed description

 The specific implementation steps of the photothermal coupling process are:

1. Adding a TiO ₂ photocatalyst carrying a noble metal promoter to a glycerin aqueous solution having a mass concentration of 0.1-40%;

 2. Turn on the agitation, evacuate the above reaction system for about 20-40 min, or use a protective gas (inert gas) to remove the air, and then seal the system;

 3. The temperature of the reaction solution is raised to 20-150 V, and then the light is irradiated for 6-24 h;

 4. The above system was cooled to 20 ° C under the action of circulating water, and the gas composition and content were analyzed by on-line gas chromatography;

 5. The reaction product solution is separated from the catalyst by filtration, and the catalyst is recovered.

 6. The liquid product was identified by high performance liquid chromatography.

 The following examples are included to illustrate the invention, but it is not intended to limit the scope of the invention as defined by the appended claims.

 Example 1

Preparation of anatase Ti0 ₂ photocatalyst

 Mix 2 mL of 37 wt% HCl with 15 ml of tetrabutyl titanate for hydrothermal, hydrothermal synthesis conditions

The mixture was centrifuged three times at 180 ° C for 36 h, and dried under vacuum at 60 ° C for 24 h to obtain Tl.

 Example 2

Preparation of Mixed Crystal Phase Ti0 ₂ Photocatalyst

 4 mL of 37 wt% HCl was mixed with 15 ml of tetrabutyl titanate for hydrothermal treatment. The hydrothermal synthesis conditions were 180 ° C, and the reaction was carried out for 36 h. The obtained product was centrifuged three times and dried at 60 ° C for 24 h to obtain T2.

 2 mL of 37 wt% HC1 was mixed with 15 ml of titanium isopropoxide for hydrothermal treatment. The hydrothermal synthesis conditions were 180 V, and the reaction was carried out for 36 h. The obtained product was centrifuged three times and dried at 60 ° C for 24 h to obtain T4.

 Example 3

Preparation of rutile phase Ti0 ₂ photocatalyst

 12 mL of 37 wt% HCl was mixed with 15 ml of tetrabutyl titanate for hydrothermal treatment. The hydrothermal synthesis conditions were 180 ° C, and the reaction was carried out for 36 h. The obtained product was centrifuged three times, and dried under vacuum at 60 ° C for 24 h to obtain T3. .

 9 mL of 37 wt% HCl was mixed with 15 ml of titanium isopropoxide for hydrothermal treatment. The hydrothermal synthesis conditions were 180 °C for 36 h. The product was centrifuged three times and dried at 60 ° C for 24 h to obtain T5.

 Example 4

Commercial Ti0 ₂ (P25 ) Hydrogen production in the reaction of photothermal catalytic glycerol aqueous solution, selectivity of glycolaldehyde and glycerol Conversion rate assessment.

Add 0.54 mL of 1 3⁄43⁄4 solution (1 11 content of 0.187 mg/mL) to 100 mL of 1 wt% glycerol aqueous solution, and add 0.1 g of commercial Ti0 ₂ (P25 ) with stirring. After the reaction system is evacuated, the reaction temperature is maintained. 20 Ό, illumination (source of 300 W Xe lamp) reaction solution, reaction for 12 h, analysis of gas composition and content by on-line gas chromatography, high-performance liquid phase detection of liquid composition and content. (The reaction results are shown in Table 1)

 Example 5

The photocatalyst T1-5 according to the present invention is evaluated for the selectivity of the product H ₂ , glycolaldehyde, and glycerol conversion after photothermal catalytic glycerin aqueous solution reaction.

The method was the same as in Example 4 except that the commercial product Ti0 ₂ (P25 ) in Example 4 was replaced with the photocatalyst T1-5 according to the invention (see Table 1 for the reaction results).

 Example 6

 Hydrogen production in the aqueous solution of photocatalytic glycerol solution reaction with different metal promoters, selectivity of glycolaldehyde and conversion of glycerol.

The method is the same as that in Example 4, except that: 0.1 g of the catalyst P25 is replaced by the O. lg T5 involved in the invention, and the RhCl ₃ solution added to the reaction solution is replaced by 0.1 mL of H ₂ PtCl<r6H _{2 .} 0 (Pt content 0.1 mg/mL), 0.1 mL PdCl ₂ (Pd content 0.1 mg/mL), 0.1 mL H ₂ AuCl<r6H ₂ 0 (Au content 0.1 mg/mL), 0.1 mL H ₂ IrCl< r6H ₂ 0 (Ir content 0.1 mg/mL), 2 mL Cu(N0 ₃ ) ₂ (Cu content 1 mg/mL), 2 mL Ni(N0 ₃ ) ₂ (Ni content 1 mg/mL). The amount of the noble metal (Pt, Pd, Au, Ir) supported was about 0.1% by weight with respect to T5, and the amount of non-precious metal (Cu, Ni) supported was about 2% by weight with respect to T5 (see Table 2 for the reaction results).

 Example 7

 Hydrogen production in the reaction of T5 photothermal catalyzed glycerol at 60 °C, selectivity of glycolaldehyde and conversion of glycerol.

0.27 mL of RhCl ₃ solution was added to 40 mL of 0.11 mmol/L glycerin aqueous solution, and 0.05 g of T5 was added with stirring. After the reaction system was evacuated, the reactor was placed in an oil bath and heated to 60 V. 300 W Xe lamp) The reaction solution was reacted for 10 h. After the reaction was completed, the system was cooled to 20 V under the action of circulating water. The composition and content of the gas are analyzed by on-line gas chromatography, and the composition and content of the liquid are detected by a high-performance liquid phase. (The reaction results are shown in Table 3)

 Example 8

The present invention relates to the conversion of the Ti0 ₂ photocatalyst evaluation T5 hydrogen production, glycolaldehyde in time thermo-catalytic reaction temperature in the aqueous solution of glycerol and glycerol selectivity.

 The method is the same as that in the embodiment 7, except that the temperature of 60 ° in Example 7 is changed to 40 V, 80 V, 100 V, and 120 °C, and the reaction results are shown in Table 3).

Table 1. Photocatalytic glycerol conversion, glycolaldehyde selectivity and hydrogen production with different crystal phase Ti0 ₂ catalysts Catalyst glycerol conversion glycolaldehyde glycolaldehyde formic acid hydrogen (mol%) selectivity (%) yield (mol%) (mmol)

 (mmol)

 P25 25.8 35.5 8.4 0.16 5.40

Tl 6.8 62.3 4.2 0.030 2.62

T2 9.2 86.4 7.9 0.085 2.10

T3 9.7 94.7 9.2 0.22 2.11

Τ4 9.9 72.5 7.2 0.086 1.99

Τ5 13.0 97.2 12.6 0.41 3.20 Table 2. T5 carrying different promoters, photocatalytic glycerol conversion, glycolaldehyde selectivity and hydrogen production

表 3、 不同温度下甘油转化率、 乙醇醛的选择性以及产氢量

Table 3. Glycerol conversion, selectivity to glycolaldehyde, and hydrogen production at different temperatures

 By using the method of glycerol conversion in the present invention, glycolaldehyde can be prepared with high selectivity, and the selectivity thereof can be over 80%, and the yield is more than 35%. The product glycolaldehyde is an important intermediate for chemical raw materials. The reaction process is simple, the reaction conditions are mild, and it is not necessary to add an acid, a base or an organic solvent, and high temperature and high pressure conditions are not required. Compared with the prior art (selective oxidation, selective hydrogenolysis, dehydration reaction, etc.), the photothermal catalytic glycerol reaction is completely green and environmentally friendly, the catalyst is cheap and easy to obtain, and the advantages of repeated use can be repeated.

Claims

Claim 1. A method of preparing glycolaldehyde glycerol utilization, characterized in that: the use of co-catalyst supported photocatalyst Ti0 _2, using the light - heat coupling method, in water, under anaerobic conditions, by one-step reaction of glycerol Conversion to glycolaldehyde;  The heat in the photo-thermal coupling method means that the reaction temperature of the reaction system is 20-150 ° C; in water, the concentration of the raw material glycerin aqueous solution is 0.1-40%.  2. The method of claim 1 wherein: The reaction formula is as follows: CH ₂ OH-CH ₂ OH-CH ₂ OH + H ₂ 0 → CH ₂ OH-CHO + 2H ₂ + HCOOH. 3. The method according to claim 1, wherein: the promoter-supporting Ti0 ₂ refers to a supported cocatalyst active component on Ti0 ₂ , and the promoter active components Pt, R, Pd, Au, Ir, One or more of Cu and Ni, and the amount of the cocatalyst supported is 0.01 to 5.0% by weight of Ti0 ₂ .  4. The method of claim 1 wherein:  The light source used in the photo-thermal coupling method includes a xenon lamp, a mercury lamp, a barium mercury lamp, a tungsten iodine lamp or sunlight, and the wavelength of the light is preferably in the range of 190 - 400 nm.  5. The method of claim 1 wherein:  The reaction to anaerobic conditions means that the vacuuming method or the inert gas excludes the air in the reaction vessel, and the inert gas is nitrogen, helium or argon;  The amount of the catalyst added in 100 ml of the aqueous glycerin solution is 0.04 - 0.2 g.  6. A method according to claim 1 or 3, characterized by:  Preparation of photocatalyst: 1) Ti0 ₂ is synthesized by hydrothermal method, and is prepared by using titanium source in the presence of inorganic acid in a hydrothermal kettle at 120-200 ° C; reaction time is 6-48 h; 2) The supported cocatalyst is realized by in-situ photoreduction deposition or immersion reduction; specifically: adding Ti0 ₂ to the soluble precursor solution of the active component of the promoter, using photoreduction; or adding Ti0 ₂ to the auxiliary After immersion and drying in the soluble precursor solution of the active ingredient of the catalyst, hydrogen reduction treatment at 300 °C 3 ho  7. The method of claim 6 wherein: the source of titanium used in the synthesis comprises tetrabutyl titanate, titanium isopropoxide, titanium tetrachloride, titanium tetrafluoride or titanium sulfate  The acid used includes hydrochloric acid, sulfuric acid, hydrofluoric acid, nitric acid or phosphoric acid;  When the amount of titanium source is 15mL, the amount of acid is 0.5-20 mL.  8. A method according to claim 7, characterized in that the source of titanium is preferably tetrabutyl titanate and titanium isopropoxide; the acid used is preferably hydrochloric acid.