阅读说明：本技术 一种由二氧化碳和氢气连续合成甲酸的方法 (Method for continuously synthesizing formic acid from carbon dioxide and hydrogen ) 是由 张兆富 刘帅帅 韩布兴 于 2019-11-25 设计创作，主要内容包括：本发明提供一种由二氧化碳和氢气连续合成甲酸的方法,更具体涉及一种利用分离膜的透过性差异分离甲酸与催化剂,从而连续生产甲酸的方法。在不需要碱助剂情况下,二氧化碳与氢气在均相催化剂的作用下生成甲酸,生成的甲酸溶液渗透通过半透膜,而催化剂由于体积大而被保留在溶液中,从而实现甲酸的连续生产。(The invention provides a method for continuously synthesizing formic acid from carbon dioxide and hydrogen, and more particularly relates to a method for continuously producing formic acid by separating formic acid from a catalyst by using the difference of permeability of a separation membrane. Under the condition of no need of alkali auxiliary agent, carbon dioxide and hydrogen are reacted under the action of homogeneous catalyst to produce formic acid, the produced formic acid solution is permeated through semi-permeable membrane, and the catalyst is retained in the solution due to its large volume so as to implement continuous production of formic acid.)

1. A method for continuously synthesizing formic acid comprises the following steps:

in an autoclave, in the presence of a catalyst, carbon dioxide and hydrogen are reacted to generate formic acid, and a formic acid solution is separated from the catalyst by adopting a selective permeation membrane, so that the continuous production of formic acid is realized.

2. The method of claim 1, wherein: the catalyst comprises a compound containing Ru, Ir or Rh and a corresponding ligand; wherein, the molar ratio of the compound containing Ru, Ir or Rh to the ligand is: 0.25: 0.6-1.2;

the ligand is at least one of 1,3,5-triaza-7-phosphaadamantane, m-tri-sulfonated triphenylphosphine sodium salt, m-mono-sulfonated triphenylphosphine sodium salt, 2' -bipyridyl-6, 6' -diol and 2,2' -biiimidinoline.

3. The method according to claim 1 or 2, characterized in that: the total pressure of the carbon dioxide and the hydrogen is 1MPa-30 MPa;

the reaction temperature is 20-90 ℃;

the reaction time is 10-240 h.

4. The method according to any one of claims 1-3, wherein: the selective permeation membrane is any one of a reverse osmosis membrane, an anion exchange membrane and a cation exchange membrane.

5. The method according to any one of claims 1-4, wherein: the selective permeation membrane is a horizontally arranged permeation membrane or a vertically arranged permeation membrane.

6. The method according to any one of claims 1-5, wherein: the reaction is carried out in water.

7. The method according to any one of claims 1-6, wherein: the reaction is carried out under the conditions of no alkali and no acid, namely, no alkaline substance or acidic substance is used as a promoter, namely, no alkali and carbonate, bicarbonate, formate and related salts thereof are added in the system.

8. The device for continuously synthesizing the formic acid is an autoclave, a polytetrafluoroethylene reaction kettle is arranged in the autoclave, and the reaction kettle is divided into two parts by a selective permeable membrane, namely a left part and a right part or an upper part and a lower part.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a method for continuously synthesizing formic acid from carbon dioxide and hydrogen, and more particularly relates to a method for continuously producing formic acid by separating formic acid from a catalyst by using the permeability difference of a separation membrane.

Background

Formic acid (HCOOH) is the simplest carboxylic acid and has a variety of uses, including silage for animal feed, the leather industry, the rubber industry, and as a feedstock for the production of other chemicals (Reid, e.b. in McGraw-Hill Encyclopedia of Science&Technology,5^thEd.；McGraw-Hill Book；New York,1982；Vol.5,p 670；Reutemann,W.；Kieczka,H.In Ullmann’s Encyclopedia of Industrial Chemistry,5^thed., respectively; elvers, b., Hawkins, s., Ravenscroft, m., roundsaville, j.f., Schulz, g., eds.; VCH Weinheim, 1989; a12, pp 13-33). More recently, the storage of hydrogen in formic acid has been causedThere is an increasing interest of researchers (Jonathan F. Hull, Yuichhiro Himeda, Wan-Hui Wang, Brian Hashiguchi, Roy Periana, David J. Szalda, James T. Mukerman 1 and Etsuko Fujita1, Nature Chemistry, 2012, 4, 383-.

The production of formic acid can be carried out by a sodium formate method, a formamide hydrolysis method, a methyl formate hydrolysis method and a light hydrocarbon oxidation method, and the sodium formate method and the methyl formate method are popularized at present. For example, patent CN106883121A discloses a method for preparing anhydrous formic acid by hydrolyzing methyl formate, which uses a reactive distillation dividing wall column to hydrolyze and separate methyl formate, and further dehydrates by a pervaporation device to obtain anhydrous formic acid. However, these production methods have serious disadvantages such as the use of highly toxic carbon monoxide as a raw material, the generation of a large amount of waste, and the like.

The reaction of carbon dioxide with hydrogen to form formic acid is an atom-economical reaction, while utilizing the greenhouse gas carbon dioxide. The reaction equation is:

CO₂+H₂＝HCO₂H ΔG^o ₂₉₈＝32.9kJ·mol^-1 [1]

standard free energy change of reaction (. DELTA.G)^o ₂₉₈) Is +32.9 kJ. mol^-1The equilibrium conversion of the reaction is low. In order to increase the conversion, an inorganic or organic base (Inoue, Y.; Izumida, H.; Sasaki, Y.; Hashimoto, H.Chem.Lett.1976, 863-. Formic acid is obtained by displacement or fractional distillation after the reaction is completed (Sakamoto, M.; Shimizu, I.; Yamamoto, A. organometallics 1994,13, 407-; 409; Anderson, J.J.; Drury, D.J.; Hamlin, J.E.; Kent, A.G. Eur. patent appl.0181078, 1986).

To further reduce the production of byproducts and energy consumption during the synthesis of formic acid from carbon dioxide, the synthesis of formic acid under alkali-free conditions has attracted the interest of many researchers (Sheng-Mei Lu, Zhijun Wang, Jun Li, Jianliang Xiao and Can Li, Green chem.,2016,18, 4553-4558; H.Hayashi, S.ogo, T.Abura and S.Fukuzumi,J.Am.Chem.Soc.,2003,125,14266). CN105283436A discloses a catalystProcess for the production of formic acid from hydrogen and carbon dioxide gases in a chemical reaction carried out in an acidic medium comprising a polar solvent (water or DMSO), in a wide temperature range and at a total gas pressure of hydrogen and carbon dioxide of up to 250 bar, without the addition of a base, a carbonate, a bicarbonate or a formate. These works do not provide a means for continuous synthesis of formic acid and extensive research is needed.

Disclosure of Invention

The invention aims to provide a method for continuously synthesizing formic acid, which adopts carbon dioxide and hydrogen to synthesize formic acid under the alkali-free condition and adopts a selective permeation membrane to realize the separation of a formic acid solution and a catalyst so as to realize the purpose of continuously producing the formic acid.

The method for continuously synthesizing the formic acid comprises the following steps:

in an autoclave, in the presence of a catalyst, carbon dioxide and hydrogen are reacted to generate formic acid, and a formic acid solution is separated from the catalyst by adopting a selective permeation membrane, so that the continuous production of formic acid is realized.

In the above process, the catalyst comprises a compound containing Ru, Ir or Rh and a corresponding ligand;

the Ru-containing compound can be RuCl₃；

The Ir-containing compound may be Pentamethylcyclopentadienylidium (III) chloride dimer ([ IrCp. Cl ]₂]₂)；

The Rh-containing compound may be RhCl₃；

The ligand may be at least one of 1,3,5-triaza-7-phosphaadamantane (1,3,5-triaza-7-phosphaadamantane, PTA), m-trisulfonated Triphenylphosphine Sodium salt (triphenylphosphinic acid trisodium salt, TPPTS), m-monosulfonated Triphenylphosphine Sodium salt (Sodium diphenylphosphinic acid-3-sulfosalt, TPPMS), 2' -dipyridine-6, 6' -diol, and 2,2' -biimizolide.

Wherein, the molar ratio of the compound containing Ru, Ir or Rh to the ligand can be: 0.25: 0.6 to 1.2, more specifically: 0.25: 1.2, 0.125: 0.3;

the total pressure of the carbon dioxide and the hydrogen can be 1MPa to 30MPa, specifically 10MPa to 15MPa, more specifically 10MPa or 15 MPa;

the reaction temperature can be 20-90 ℃, specifically 40-60 ℃, 60-80 ℃, more specifically 60 ℃, 70 ℃ or 80 ℃;

the reaction time can be 10-240h, specifically 17-24h, more specifically 24 h;

the selective permeation membrane can be any one of a reverse osmosis membrane, an anion exchange membrane and a cation exchange membrane; specifically, the membrane can be a reverse osmosis membrane, more specifically a Dow RO membrane;

the selective permeation membrane can be a horizontally arranged permeation membrane or a vertically arranged permeation membrane.

The reaction is carried out in water;

the reaction is carried out under the conditions of no alkali and no acid, namely, no alkaline substance or acidic substance is used as a promoter, namely, no alkali and no Carbonate (CO) exist in the system₃ ^2-) Bicarbonate radical (HCO)₃ ^-) Formate (HCOO)^-) And the addition of salts related thereto;

introducing inert gas into the autoclave for emptying before reaction;

the method can also further comprise the operation of carrying out reduced pressure degassing treatment on the prepared formic acid solution to collect formic acid gas.

The above-described continuous synthesis of formic acid is carried out in an autoclave provided with a selectively permeable membrane.

The cross-sectional view of the autoclave is shown in FIG. 1;

the inside of the autoclave is a polytetrafluoroethylene reaction kettle, and the reaction kettle is divided into two parts by a selective permeable membrane, namely a left part and a right part (shown in figure 1 a) or an upper part and a lower part (shown in figure 1 b).

In the autoclave shown in fig. 1a, the autoclave is divided into a left part and a right part by the selective permeation membrane (4), a stirring magneton (6) is arranged on one side of the selective permeation membrane (4), and a catalyst solution is added on the side (i.e. a reaction side) provided with the stirring magneton;

the top of the reaction kettle is provided with an air inlet valve (3), and compressed carbon dioxide and hydrogen are sequentially introduced into the reaction kettle through the air inlet valve;

an inlet valve (1) is arranged at the top of the other side (non-reaction side), and water is introduced into the other side (non-reaction side) from the inlet valve at a certain flow rate;

and an outlet valve (2) is arranged at the lower part of the other side (non-reaction side), and the formic acid aqueous solution is discharged out of the reaction kettle through the outlet valve.

In the autoclave shown in fig. 1b, the autoclave is divided into an upper part and a lower part by the permselective membrane (4), a stirring magneton (6) is arranged on the upper side of the permselective membrane (4), and a catalyst solution is added to the upper side (i.e. the reaction side) provided with the stirring magneton;

an air inlet valve (3) is arranged at one end of the top of the upper side of the selective permeation membrane (4), and compressed carbon dioxide and hydrogen are sequentially introduced into the reaction kettle through the air inlet valve;

the other end of the top of the upper side is provided with an inlet valve (1), and water is introduced into the reaction kettle from the inlet valve at a certain flow rate;

an outlet valve (2) is arranged at the bottom of the lower side of the selective permeation membrane (4), and the formic acid aqueous solution is discharged out of the reaction kettle through the outlet valve.

When the autoclave shown in fig. 1a is used, a catalyst is dissolved in one side (namely, a reaction side) of a selective permeation membrane, compressed carbon dioxide and hydrogen are introduced into a system to a certain pressure, stirring is continuously carried out at a certain temperature, the carbon dioxide and the hydrogen react to generate formic acid, and the generated formic acid is dissolved in water; injecting water into the other side (non-reaction side) of the membrane in the reaction kettle at a certain flow rate by using a liquid pump, wherein formic acid in the solution enters the flowing side by diffusion due to different concentrations at the two sides of the membrane, and the aqueous solution in which the formic acid is dissolved is discharged through an outlet to keep the liquid level in the reaction tank unchanged, thereby realizing the continuous production of the formic acid;

when the autoclave shown in fig. 1b is used, the catalyst is dissolved on the upper side of the selective permeation membrane, the compressed carbon dioxide and hydrogen are introduced into the system to a certain pressure, the mixture is continuously stirred at a certain temperature, the carbon dioxide and the hydrogen react to generate formic acid, and the generated formic acid is dissolved in water; the formic acid solution on the upper layer enters the lower layer through permeation, and the catalyst is blocked and remains on the upper layer; injecting water into the upper layer of a reaction tank in the high-pressure kettle at a certain flow rate by using a liquid pump, continuously discharging formic acid solution from the lower layer, and keeping the liquid level in the reaction tank unchanged, thereby realizing the continuous production of formic acid;

wherein, the flow rate of the water can be as follows: 0.2ml/h-2 ml/h.

Compared with the prior art, the method overcomes the problem of separation of the catalyst and the product under high pressure, and realizes continuous production of formic acid.

Drawings

FIG. 1 is a sectional view of an autoclave used in the present invention, wherein FIG. 1a is a sectional view of an autoclave with a permeation membrane disposed horizontally and FIG. 1b is a sectional view of an autoclave with a permeation membrane disposed vertically. Wherein, (1) is an inlet valve, (2) is an outlet valve, (3) is an air inlet valve, (4) is a selective permeation membrane, (5) is a polytetrafluoroethylene reaction kettle, and (6) is a stirring magneton.

Detailed Description

The present invention will be described below with reference to specific examples, but the present invention is not limited thereto.

The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.

Examples

Screening of the catalyst

Example 1 Using Autoclave a, an anion exchange membrane (purchased from Beijing Tanzui technology development Co., Ltd.) was selected as the permselective membrane, 25 ml of water was placed on the magneton side of the reactor, and 0.25. mu.M RuCl was added₃1.2 micromoles of 1,3,5-triaza-7-phosphaadamantane (1,3,5-triaza-7-phosphaadamantane, PTA), sealing, adding nitrogen gas under 3 atmospheric pressures, discharging, and cyclically adding nitrogen gas for 5 times. Heating to 60 ℃, adding carbon dioxide to 5MPa, adding hydrogen to total pressure of 10MPa, and continuously stirring. The liquid pump is started to pump 1 mm from the water inletPumping water every hour, and continuously discharging the water from a water outlet to keep the liquid level in the reaction kettle unchanged. After 24 hours of reaction, the solution obtained in the last hour was degassed under reduced pressure by a water pump, and then titrated with sodium hydroxide (phenolphthalein as an indicator) to obtain a formic acid solution with a concentration of 0.027 mol/L.

Example 2, exactly the same reaction conditions and detection method as in example 1 were used, except that the ligand was replaced with 1.2. mu. mol of sodium Triphenylphosphine tri (3, 3', 3 "-trisulfonic acid trisodium salt, TPPTS), and the concentration of the resulting formic acid solution was 0.025mol/L as in example 1.

Example 3 exactly the same reaction conditions and detection method as in example 1 were used except that the ligand was replaced with 1.2. mu. mol of Sodium sulfotriphenylphosphine (TPPMS), and the concentration of the resulting formic acid solution was 0.018mol/L as in example 1.

Example 4, using exactly the same reaction conditions and detection methods as in example 1, the catalyst was replaced with only 0.125 micromolar pentanethylcyclopentadienylirdium (iii) chloride dimer ([ IrCp × Cl ])₂]₂) The ligand was replaced with 0.3. mu. mol of 2,2 '-dipyridine-6, 6' -diol, and the concentration of the resulting formic acid solution was 0.019mol/L in the same manner as in example 1.

Example 5, exactly the same reaction conditions and detection method as in example 4 were used, except that the ligand was changed to 0.3. mu. mol of 2,2' -biidizoline, and the rest was the same as in example 1, and the concentration of the obtained formic acid solution was 0.024 mol/L.

Example 6 Using exactly the same reaction conditions and detection method as in example 1, the catalyst was changed to 0.25. mu. mol of RhCl only₃In the same manner as in example 1, the concentration of the obtained formic acid solution was 0.026 mol/L.

Influence of reaction time

Example 7 was carried out under exactly the same reaction conditions and detection methods as in example 1 except that the solution obtained within one hour from the start of the reaction was measured, and the concentration of the obtained formic acid solution was 0.0031mol/L as in example 1.

Example 8 exactly the same reaction conditions and detection methods as in example 7 were used, and only the solution obtained in the reaction time of 5 to 6 hours was measured, and the concentration of the obtained formic acid solution was 0.0131mol/L as in example 7.

Example 9 and exactly the same reaction conditions and detection methods as in example 7 were used, and only the solution obtained in the reaction time of 10 to 11 hours was measured, and the concentration of the obtained formic acid solution was 0.0195mol/L as in example 7.

Example 10 exactly the same reaction conditions and detection methods as in example 7 were used, and only the solution obtained in the reaction time of 17 to 18 hours was used for the measurement, and the concentration of the obtained formic acid solution was 0.025mol/L as in example 7.

Example 11 and exactly the same reaction conditions and detection methods as in example 7 were used, and only the solution obtained in the reaction time of 23 to 24 hours was measured, and the concentration of the obtained formic acid solution was 0.027mol/L as in example 7.

Example 12, exactly the same reaction conditions and detection methods as in example 7 were used, and only the solution obtained in the reaction time of 29 to 30 hours was measured, and the concentration of the obtained formic acid solution was 0.0271mol/L as in example 7.

Influence of reaction pressure

Example 13 the same reaction conditions and detection method as in example 1 were adopted except that the total reaction pressure was changed to 1MPa, and the concentration of the obtained formic acid solution was 0.0025mol/L as in example 1.

Example 14, the same reaction conditions and detection method as in example 1 were adopted, except that the total reaction pressure was changed to 4MPa, and the concentration of the obtained formic acid solution was 0.0098mol/L as in example 1.

Example 15, the same reaction conditions and detection method as in example 1 were adopted, except that the total reaction pressure was changed to 7MPa, and the concentration of the obtained formic acid solution was 0.015mol/L as in example 1.

Example 16, the same reaction conditions and detection method as in example 1 were adopted, except that the total reaction pressure was changed to 15MPa, and the concentration of the obtained formic acid solution was 0.032mol/L as in example 1.

Influence of reaction temperature

Example 17, the same reaction conditions and detection method as in example 1 were adopted, only the reaction temperature was changed to 30 ℃, and the concentration of the obtained formic acid solution was 0.008mol/L as in example 1.

Example 18, the same reaction conditions and detection method as in example 1 were adopted, only the reaction temperature was changed to 40 ℃, and the concentration of the obtained formic acid solution was 0.0115mol/L as in example 1.

Example 19, the same reaction conditions and detection method as in example 1 were adopted, only the reaction temperature was changed to 50 ℃, and the concentration of the obtained formic acid solution was 0.016mol/L as in example 1.

Example 20, the same reaction conditions and detection method as in example 1 were adopted, except that the reaction temperature was changed to 70 ℃, and the concentration of the obtained formic acid solution was 0.039mol/L as in example 1.

Example 21, the same reaction conditions and detection method as in example 1 were adopted, except that the reaction temperature was changed to 80 ℃, and the concentration of the obtained formic acid solution was 0.042mol/L as in example 1.

Influence of Water inflow

Example 22, the same reaction conditions and detection method as in example 1 were adopted, only the flow rate of water injected from the water inlet was changed to 0.2ml/h, and the concentration of the obtained formic acid solution was 0.054mol/L as in example 1.

Example 23, the same reaction conditions and detection method as in example 1 were adopted, only the flow rate of water injected from the water inlet was changed to 0.5ml/h, and the concentration of the obtained formic acid solution was 0.038mol/L as in example 1.

Example 24, the same reaction conditions and detection method as in example 1 were adopted, only the flow rate of water injected from the water inlet was changed to 2ml/h, and the concentration of the obtained formic acid solution was 0.022mol/L as in example 1.

Example 25, the same reaction conditions and detection method as in example 1 were adopted, only the reaction temperature was changed to 70 ℃, the flow rate of water injected from the water inlet was changed to 2ml/h, and the concentration of the obtained formic acid solution was 0.029mol/L, as in example 1.

Example 26, the same reaction conditions and detection method as in example 25 were adopted, and only the flow rate of water injected from the water inlet was changed to 1ml/h, and the concentration of the obtained formic acid solution was 0.038mol/L as in example 25.

Example 27, the same reaction conditions and detection method as in example 25 were adopted, only the flow rate of water injected from the water inlet was changed to 0.5ml/h, and the concentration of the obtained formic acid solution was 0.043mol/L as in example 25.

Example 28, the same reaction conditions and detection method as in example 25 were adopted, only the flow rate of water injected from the water inlet was changed to 0.2ml/h, and the concentration of the obtained formic acid solution was 0.047mol/L as in example 25.

Influence of permselective membranes

Example 29 the same reaction conditions and detection method as in example 1 were used, and only the permselective membrane was changed to 7001 anion exchange membrane manufactured by Membranes International inc. and the remaining example 1 was used, and the concentration of the obtained formic acid solution was 0.019 mol/L.

Example 30, the same reaction conditions and detection method as in example 1 were adopted, except that only the permselective membrane was changed to a Nafion N-115 cation exchange membrane, and the remainder was the same as in example 1, and the concentration of the obtained formic acid solution was 0.003 mol/L.

Example 31 the same reaction conditions and detection method as in example 1 were adopted, except that only the permselective membrane was changed to a reverse osmosis membrane (dow RO membrane), and the concentration of the obtained formic acid solution was 0.027mol/L as in example 1.

Stability of the System

Example 32, exactly the same reaction conditions and detection methods as in example 1 were used, and the reaction was continued for 10 days to obtain 240ml of a product having a concentration of 0.027 mol/L.

Autoclave b

Example 33, the same reaction conditions and detection method as in example 1 were adopted, only the autoclave used was replaced with autoclave b (fig. 1b), and the concentration of the obtained formic acid solution was 0.027mol/L, the same as in example 1.

Example 34, the same reaction conditions and detection method as in example 33 were adopted, and the concentration of the formic acid solution obtained in the same manner as in example 33 except that the membrane used was changed to the Dow RO membrane, was 0.028 mol/L.

The effect of the various reaction conditions on the yield of formic acid was compared by examples 1 to 34: (1) the yield is improved by increasing the pressure; (2) the yield is complicated by the increase in temperature, which can increase the yield of formic acid at higher flow rates and decrease it at lower flow rates; (3) the selectively permeable membrane has a great influence on the yield of formic acid.

Finally, the following results are obtained: the selective permeation membrane can effectively separate the formic acid formed by carbon dioxide and hydrogen from a homogeneous catalysis system, thereby achieving the purpose of continuously producing the formic acid.