CN1789256A - Preparation of 2-methylfuran and cyclohexanone by couple method - Google Patents
Preparation of 2-methylfuran and cyclohexanone by couple method Download PDFInfo
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- CN1789256A CN1789256A CNA2005100481939A CN200510048193A CN1789256A CN 1789256 A CN1789256 A CN 1789256A CN A2005100481939 A CNA2005100481939 A CN A2005100481939A CN 200510048193 A CN200510048193 A CN 200510048193A CN 1789256 A CN1789256 A CN 1789256A
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- cyclohexanol
- furfural
- cyclohexanone
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- methylfuran
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Abstract
A coupling method for preparing 2-methylfuran and cyclohexanone, carrying out integral reaction with the mixture of furfuraldehyde and anhydride under the condition of gas phase, existence of additional hydrogen or no additional hydrogen, proper temperature and hydrogen catalyst. The invention is characterized by the low energy consumption, no need for hydrogenation or hydrogen recovery, low producing cost, high selectivity and productivity, simple preparing process and easy-to-operate.
Description
Field of the invention
The invention belongs to a method for preparing 2-methylfuran and cyclohexanone, and particularly relates to a method for preparing 2-methylfuran and cyclohexanone by taking furfural and cyclohexanol as raw materials.
Background
The 2-methylfuran is mainly applied to the aspects of medicines, pesticides and fine chemical engineering; 2-methylfuran, particularly in the pharmaceutical industry, as a pharmaceutical intermediate for the preparation ofVitamin B1Chloroquine phosphate, herborinine phosphate and other medicine.
At present, 2-methylfuran is industrially prepared by a furfural gas-phase catalytic hydrogenation method. China is a large country for producing furfural, and 2-methylfuran is a product with high added value in furfural deep-processing products.
The Soviet Union patent SU941366 and the Chinese patent CN1145274A both report a technical route for preparing 2-methylfuran by furfural gas-phase hydrogenation.
The gas-phase hydrogenation of furfural to prepare 2-methylfuran is a series reaction, and due to strong heat release limitation, liquid space velocity is low in general 2-methylfuran production plants, and in addition, a hydrogen source needs to be additionally provided.
Equation of reaction see formula (1)
Furfural 2-methylfuran strong heat release
Mechanism of reaction
Other side reactions
Cyclohexanone is a colorless oily liquid, soluble in water, alcohol, ether and common solvents, with a clay fragrance. Cyclohexanone is used as an important chemical raw material for preparing nylon intermediates such as caprolactam, adipic acid and the like. Cyclohexanone is an excellent medium-to-high boiling organic solvent with excellent solubility and low volatility. It can dissolve polyvinyl acetate, polyurethane, polymethyl methacrylate, ABS resin, etc., and can also dissolve polystyrene, alkyd resin, acrylic resin, natural rubber, synthetic rubber, chlorinated rubber, etc. When the cyclohexanone is used as a coating solvent, the coating has good spraying and brushing functions and can improve the gloss of a coating. It can also be used as silk screen ink solvent, photosensitive material coating solvent, polishing agent and leather degreasing agent in leather-making and shoe-making industry, and coating diluent, and can also be used for preparing spray insecticide in pesticide industry. With the increasing development of science and technology, the application and development of cyclohexanone are developing towards wider fields.
The preparation of cyclohexanone from cyclohexanol mainly includes two processes, oxidation and dehydrogenation. The dehydrogenation process has less side reaction, easy operation, high yield and high safety, so that industrial production of cyclohexanone in large scale is generally carried out by using cyclohexanol dehydrogenation. Industrially, catalytic dehydrogenation of cyclohexanol is carried out by gasifying pure cyclohexanol and passing it through a heated dehydrogenation tube furnace together with hydrogen for continuous gas phase catalytic dehydrogenation. Cooling the reaction mixture by a condenser, distilling and purifying the crude product, removing a small amount of water and cyclohexene from the tower top, and carrying out reduced pressure distillation by a high-efficiency rectifying tower under the pressure of about 4kPa to ensure that the content of cyclohexanone in the product reaches 98-99%.
Chinese patents CN1169417A and CN1381434A, japanese patent JP2000288395, etc. report a process route for preparing cyclohexanone by dehydrogenation of cyclohexanol.
The equation for preparing cyclohexanone by cyclohexanol dehydrogenation is as follows:
moderate endotherm of cyclohexanol cyclohexanone
Other side reactions
The preparation of cyclohexanone by cyclohexanol dehydrogenation is thermodynamically reversible endothermic reaction, because of reaction heat absorption, the high liquid level and the air level of cyclohexanone cannot be fully exerted due to the influence of heat transfer in the actual production process, and meanwhile, the conversion rate of cyclohexanone prepared by cyclohexanol dehydrogenation is not high due to the characteristic of limitation of thermodynamic balance, in addition, the hydrogen generated by reaction is wasted when being discharged, and the production cost is increased if the hydrogen is recovered by a series of unit operations.
Disclosure of Invention
The invention aims to provide a method for preparing cyclohexanone and 2-methylfuran by coupling cyclohexanol and furfural serving as raw materials at low cost without a hydrogen source.
The purpose of the invention is realized as follows: according to the traditional technical route, by-product hydrogen produced in the process of producing cyclohexanone by cyclohexanol dehydrogenation is directly discharged or recovered through various unit operations, so that the production cost is increased. In addition, in the enterprises for producing 2-methylfuran by furfural hydrogenation, hydrogen sources need to purchase or build hydrogen production equipment from other places, so that the cost is increased; therefore, the two processes are combined into one, and the hydrogen source can be fully utilized, see formula (3):
furfural cyclohexanol 2-methyl furan cyclohexanone weak heat release
The hydrogenation dehydrogenation coupling equation can obtain the molar ratio of the cyclohexanol and the furfural of 2: 1,
considering factors such as system air leakage, emptying required by accumulation of inert gas, incomplete conversion of cyclohexanol and the like in the actual process, the molar ratio of cyclohexanol to furfural is more than 2 under general conditions.
The preparation method of the invention comprises the following steps:
the mixture of cyclohexanol and furfural is subjected to integrated reaction at proper temperature and hydrogenation catalyst under the conditions of gas phase, additional hydrogen or no additional hydrogen.
Since the catalysts used in accordance with the invention are generally used industrially as hydrogenation (i.e. hydrogenation) catalysts, these catalysts, although having a dehydrogenation action within the scope of the invention, continue to be referred to as "hydrogenation catalysts" in the process described in accordance with the invention.
In the method, the mixture of the cyclohexanol and the furfural is subjected to dehydrogenation and hydrogenation integrated reaction under the conditions of gas phase, hydrogenation catalyst, the molar ratio of circulating hydrogen/the mixture of the cyclohexanol and the furfural is 5-50, the molar ratio of cyclohexanol/the furfural is 3-5, the reaction pressure is usually normal pressure, and the reaction temperature is 250-270 ℃ to generate cyclohexanone and 2-methylfuran.
As the heterogeneous catalyst in the present process, not only a precipitated catalyst but also an impregnated supported catalyst can be used. The precipitated catalyst can be prepared as follows: the catalytically active components are first precipitated from their salt solutions, in particular from their nitrate and/or acetate solutions, by adding alkali metal and/or alkaline earth metal hydroxide solutions and/or carbonate solutions, for example as sparingly soluble hydroxides, oxide hydrates, basic salts or carbonates, the resulting precipitates are subsequently filtered, washed and dried and calcined, usually at 300-500 ℃ to convert them into the corresponding oxides, mixed oxides and/or mixed-valence oxides, which are reduced to the corresponding metal and/or lower-oxidation-valence oxides by treatment with hydrogen or hydrogen-containing gases, usually at 100-300 ℃. Other suitable reducing agents may be selected for this purpose, such as: formaldehyde, hydrazine, to replace hydrogen, although the most economically valuable is hydrogen. Usually under certain reducing condition, the reaction is carried out until no hydrogen is consumed, or the inlet and the outlet of a catalyst bed layerThe hydrogen content and the amount of water generated are the same. Precipitated catalyst CuO/Cr2O3The weight percentage composition of CuO is 40-62%, Cr2O338 to 60 percent. Preparation of a supported catalyst: it may be advantageous to impregnate the active ingredient directly with the carrier, or to precipitate the active ingredient and carrier simultaneously from the relevant salt solution. The catalyst is composed of CuO/active carbon, wherein the CuO is 10-15 wt%; pd/active carbon, which contains Pd0.01wt%.
The process of the invention is preferably carried out continuously. In this case, a tubular reactor may be used, in which the catalyst is preferably arranged in the form of a fixed bed.
The starting materials cyclohexanol and furfural may be vaporized in an evaporator before they are passed over the catalyst. The starting materials are preferably vaporized in a carrier gas stream, which can be used as carrier gas, for example: noble gases, nitrogen or C1-C4Hydrocarbons, preferably methane and most preferably hydrogen.
The carrier gas stream used for the vaporization of the starting material is preferably formed as a loop, i.e.the product contained in the carrier gas stream on leaving the catalyst bed can be reused for the vaporization of the starting material as a carrier gas stream after it has been separated off in a gas-liquid separator or in a condenser.
The gas state crude product from the reactor is cooled and condensed to become liquid crude product, and then sampling analysis can be carried out to obtain the crude product composition, and the activity and selectivity of the catalytic reaction can be mastered. The crude product can be treated in a traditional way, and by-products are removed through fractional distillation to obtain qualified products.
Compared with the prior art, the invention has the following advantages:
(1) the two reactions carried out separately are combined together, so that the hydrogen obtained by dehydrogenation is prevented from being compressed and then hydrogenated in another reactor.
(2) Dehydrogenation is an endothermic reaction, hydrogenation is an exothermic reaction, and the coupling of the two can relieve the heat effect in the reaction process. Coupling would be an efficient process.
(3) The hydrogen production equipment is saved in the hydrogenation and dehydrogenation integrated process.
(4) The invention needs less energy for reaction and does not need hydrogenation or hydrogen recovery.
In the following examples, the conversions and selectivities given are determined by gas chromatography. Since the target products of the integration of cyclohexanol dehydrogenation and furfural hydrogenation are cyclohexanone and 2-methylfuran, the selectivity of cyclohexanone and 2-methylfuran is calculated according to the following method:
cyclohexanone selectivity (100% × (moles cyclohexanone in product)/(moles cyclohexanol converted) of cyclohexanone in product)
2-Methylfuran Selectivity (mole of 2-methylfuran in product)/(mole of converted furfural) of 100 × (mole of 2-methylfuran in product)
Detailed Description
COMPARATIVE EXAMPLE 1 Furfural gas-phase atmospheric hydrogenation to 2-methylfuran
(1) The preparation process of the catalyst comprises the following steps: weighing the required copper nitrate and chromium nitrate, carrying out parallel flow with an ammonium carbonate solution for precipitation, adjusting the flow rate of the two solutions to keep the pH value at about 6-7, and precipitatingAnd filtering, washing, drying and calcining the precipitate at 350 ℃, and finally adding 1% of graphite powder to perform tabletting and molding to obtain the required catalyst sample. The catalyst used in the present example comprises the following components in percentage by mass: CuO 49% Cr2O3 51％
(2) The reaction performance is as follows:
the catalyst activity evaluation and stability test were conducted in a fixed bed evaluation apparatus (commonly referred to as a pilot plant). The reactor is made of a stainless steel pipe with the inner diameter of 12mm and the length of 500mm, the center of the reactor is provided with a thermal couple sleeve pipe with the diameter of ∅ 4mm, the outside of the reactor is provided with a metal sleeve pipe, and an electric furnace wire is wound on the metal sleeve pipe. The reaction temperature was measured by an ∅ 1mm sheathed thermocouple inserted into the central cannula and controlled by a temperature controller (via a solid state relay). Each evaluation was charged with 5 g, about 4.5 ml of catalyst (20-40 mesh). The height of the catalyst bed layer is about 50mm and is positioned at the constant-temperature section of the reaction tube. Before activity evaluation, the catalyst needs to be reduced by hydrogen, and the space velocity of reducing gas is more than 500h-1. The bed layer is gradually heated in the reduction process, and about 30 hours are needed from room temperature to 270 DEG C. And after the reduction is finished, feeding.
At normal pressure, a hydrogen-aldehyde ratio of 15: 1 and a liquid space velocity of 0.2hr-1Under the condition of (1), when the reaction temperature is 250 ℃, the conversion rate of furfural is 99.2 percent, and the selectivity of 2-methylfuran is 87.5 percent. When the reaction temperature is 270 ℃, the conversion rate of the furfural is 99.9 percent, and the selectivity of the 2-methylfuran is 82.6 percent. During the reaction operation, hydrogen gas is continuously replenished.
Comparative example 2 preparation of Cyclohexanone from cyclohexanol by atmospheric dehydrogenation
The catalyst was packed in a gas phase fixed bed reactor (the composition of the packed catalyst and the structure of the activation reduction and reactor are the same as in comparative example 1) at atmospheric pressure, a hydrogen-alcohol ratio of 7: 1, and a liquid space velocity of 0.8hr-1Under the condition of (1), when the reaction temperature is 250 ℃, the conversion rate of the cyclohexanol is 48.4 percent, and the selectivity of the cyclohexanone is 87.0 percent. When the reaction temperature is 270 ℃, the conversion rate of the cyclohexanol is 60.5 percent, and the selectivity of the cyclohexanone is 85.6 percent. In the normal reaction process, hydrogen is required to be continuously discharged out of the circulating system.
Example 1
In a gas-phase fixed bed reactor (the composition of the catalyst and the structure of the activation reduction and the reactor are the same as those in comparative example 1), respectively vaporized cyclohexanol and furfural are mixed with circulating hydrogen according to the molar ratio of 4.3: 1 and then enter the reactor. At normal pressure, the total space velocity of the liquid is 1.0hr-1Under the condition that the molar ratio of the circulating hydrogen to the mixture is 5: 1 and the temperature is 250 ℃, the conversion rate of the cyclohexanol is 48.6 percent, the conversion rate of the furfural is 99.7 percent, the selectivity of the cyclohexanone is 95.8 percent, and the selectivity of the 2-methylfuran is 90.7 percent; when the reaction temperature is 270 ℃, the conversion rate of cyclohexanol is 62.1%, the conversion rate of furfural is 99.9%, the selectivity of cyclohexanone is 93.4%, and the selectivity of 2-methylfuran is 86.4%; after normal operation reaction, no external hydrogen supply is needed.
Example 2
In a gas-phase fixed-bed reactor (catalyst composition and activation reduction and reactor structure as in comparative example 1) at atmospheric pressure and a reaction temperature of 260 deg.C, cyclohexanol and furfural were separately vaporized4: 1 molar ratio, the molar ratio of the circulating hydrogen to the mixed raw materials is 10: 1, and the total liquid space velocity is about 0.7hr-1Condition (C) ringThe conversion rate of the hexanol is 53.6 percent, the conversion rate of the furfural is 99.9 percent, the selectivity of the cyclohexanone is 94.5 percent, and the selectivity of the 2-methylfuran is 88.6 percent.
Example 3
In a gas-phase fixed bed reactor (the composition of the catalyst and the structure of the activating reduction reactor are the same as those in the comparative example 1), the reaction pressure is normal pressure, the reaction temperature is 270 ℃, the respectively vaporized cyclohexanol and furfural have the molar ratio of 3.6: 1, the molar ratio of circulating hydrogen to mixed raw materials is 25: 1, and the total liquid space velocity is about 0.6hr-1The conditions include cyclohexanol conversion rate of 59.0%, furfural conversion rate of 99.6%, cyclohexanone selectivity of 94.8% and 2-methylfuran selectivity of 87.8%.
Example 4
In a gas-phase fixed bed reactor (the composition of the catalyst and the structure of the activation reduction and reactor are the same as those in comparative example 1), the reaction temperature is 266 ℃, the respectively vaporized cyclohexanol and furfural have the molar ratio of 3.8: 1, the molar ratio of the circulating hydrogen to the mixed raw materials is 50: 1, and the total liquid space velocity is about 0.8hr-1The conditions include 55.6% of cyclohexanol conversion rate, 99.9% of furfural conversion rate, 95.2% of cyclohexanone selectivity and 88.2% of 2-methylfuran selectivity.
Example 5
In a gas-phase fixed bed reactor (the mass percentage of each component of the catalyst used in the example is CuO 47 percent Cr2O353 percent. The catalyst preparation method, the activation reduction and the reactor structure are the same as the comparative example 1), the reaction temperature is 260 ℃ under normal pressure, the respectively vaporized cyclohexanol and furfural have the molar ratio of 4: 1, the molar ratio of circulating hydrogen to mixed raw materials is 5: 1, and the total liquid space velocity is about 1hr-1The conditions include cyclohexanol conversion of 55.2%, furfural conversion of 99.8%, cyclohexanone selectivity of 95.5% and 2-methylfuran selectivity of 88.9%.
Example 6
The catalyst used in the present example had a composition (mass percentage) of CuO of 10% and activated carbon of 90%; the preparation method comprises the following steps: the carrier is impregnated with a copper solution to which an ammonium carbonate solution is added dropwise, and the impregnated carrier is dried at 110 ℃ and calcined at 400 ℃ (under nitrogen atmosphere). The catalyst activation reduction and the reactor configuration were the same as in comparative example 1. At normal pressure and reaction temperatureAt 266 deg.C, the cyclohexanol and furfural are respectively vaporized according to a molar ratio of 3.7: 1, the molar ratio of circulating hydrogen to mixed raw material is 5: 1, and the total liquid space velocity is about 0.8hr-1The conditions include cyclohexanol conversion of 59.2%, furfural conversion of 99.9%, cyclohexanone selectivity of 94.5%, and 2-methylfuran selectivity of 87.8%.
Example 7
The catalyst used in the present example had a composition (mass percentage) of CuO of 15% and activated carbon of 85%; the catalyst was prepared in the same manner as in example 6. Catalyst activation reduction and reactor configuration comparisonExample 1. At normal pressure and reaction temperature of 255 ℃, the cyclohexanol and the furfural which are respectively vaporized according to the molar ratio of 5: 1, the molar ratio of the circulating hydrogen to the mixed raw materials of 15: 1, and the total liquid space velocity of about 0.9hr-1The conditions include 48.2% of cyclohexanol conversion, 99.0% of furfural conversion, 95.5% of cyclohexanone selectivity and 89.8% of 2-methylfuran selectivity.
Example 8
The catalyst used in this example had a composition (mass%) of Pd 0.01%. The preparation method comprises the following steps: the carrier is impregnated with a palladium solution to which ammonium bicarbonate is added dropwise, and the impregnated carrier is dried at 110 ℃ and calcined at 450 ℃ (nitrogen gas protection). The catalyst activation reduction and the reactor configuration were the same as in comparative example 1. At normal pressure and reaction temperature of 255 ℃, the cyclohexanol and the furfural which are respectively vaporized according to the molar ratio of 5: 1, the molar ratio of the circulating hydrogen to the mixed raw materials of 5: 1, and the total liquid space velocity of about 1hr-1The conditions include cyclohexanol conversion of 51.2%, furfural conversion of 99.3%, cyclohexanone selectivity of 92.5% and 2-methylfuran selectivity of 87.6%.
Claims (8)
1. A method for preparing 2-methylfuran and cyclohexanone by coupling is characterized in that a mixture of furfural and cyclohexanol is subjected to integrated reaction at a proper temperature on a hydrogenation catalyst under the conditions of gas phase, additional hydrogen or no additional hydrogen.
2. The method of claim 1, wherein the mixture of cyclohexanol and furfural is subjected to dehydrogenation and hydrogenation integrated reaction under gas phase conditions, at a hydrogenation catalyst, at a molar ratio of recycle hydrogen/mixture of cyclohexanol and furfural of 5-50, a molar ratio of cyclohexanol/furfural of 3-5, a reaction pressure of normal pressure, and a reaction temperature of 250-.
3. The method of claim 1 or 2, wherein the hydrogenation catalyst is CuO/Cr2O3CuO/activated carbon, Pd/activated carbon.
4. The method of claim 3, wherein the CuO/Cr is selected from the group consisting of2O3The catalyst comprises the following components in percentage by weight: 40-62% of CuO and Cr2O338-60％。
5. The method of claim 3, wherein the CuO/activated carbon catalyst comprises CuO 10-15 wt%.
6. The method of claim 3, wherein the Pd/activated carbon catalyst comprises Pd0.01 wt%.
7. A process for the coupled preparation of 2-methylfuran and cyclohexanone according to claim 1 or 2, characterized in that the mixture of furfural and cyclohexanol is vaporized in a stream of carrier gas, noble gas, nitrogen or C1-C4A hydrocarbon.
8. The method of claim 7, wherein the carrier gas is methane or hydrogen.
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| CNA2005100481939A CN1789256A (en) | 2005-12-14 | 2005-12-14 | Preparation of 2-methylfuran and cyclohexanone by couple method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112517013A (en) * | 2020-12-23 | 2021-03-19 | 中科合成油技术有限公司 | Cu-based catalyst and method for preparing gamma-valerolactone and delta-cyclopentanolactone by using same |
| CN112569965A (en) * | 2020-12-23 | 2021-03-30 | 内蒙古工业大学 | Double-transition metal hierarchical pore catalyst and preparation method and application thereof |
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2005
- 2005-12-14 CN CNA2005100481939A patent/CN1789256A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112517013A (en) * | 2020-12-23 | 2021-03-19 | 中科合成油技术有限公司 | Cu-based catalyst and method for preparing gamma-valerolactone and delta-cyclopentanolactone by using same |
| CN112569965A (en) * | 2020-12-23 | 2021-03-30 | 内蒙古工业大学 | Double-transition metal hierarchical pore catalyst and preparation method and application thereof |
| CN112569965B (en) * | 2020-12-23 | 2022-09-09 | 内蒙古工业大学 | Double-transition metal hierarchical pore catalyst and preparation method and application thereof |
| CN112517013B (en) * | 2020-12-23 | 2023-07-28 | 中科合成油技术股份有限公司 | Cu-based catalyst and method for preparing gamma-valerolactone and delta-cyclopentalactone by using same |
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