CN1142325C - Process for preparing p-aminophenol by electrolytic reduction of nitrobenzene - Google Patents
Process for preparing p-aminophenol by electrolytic reduction of nitrobenzene Download PDFInfo
- Publication number
- CN1142325C CN1142325C CNB011133147A CN01113314A CN1142325C CN 1142325 C CN1142325 C CN 1142325C CN B011133147 A CNB011133147 A CN B011133147A CN 01113314 A CN01113314 A CN 01113314A CN 1142325 C CN1142325 C CN 1142325C
- Authority
- CN
- China
- Prior art keywords
- aminophenol
- catholyte
- meter
- mirbane
- oil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The present invention relates to a preparation method for p-aminophenol by the electrolytic reduction of nitrobenzene. In the present invention, by adding antioxidants into a cathode electrolyte and regulating electric current density and the flow velocity of the cathode electrolyte in time according to the concetration change of the p-aminophenol, the selectivity of the p-aminophenol in electrolytic processes and current efficiency are improved so that the yield of the p-aminophenol is increased without a recovering solvent, and thus, the present invention has the advantages of reduced production cost and easy implementation of industrialization.
Description
Technical field
The present invention relates to the production technique of p-aminophenol, relate in particular to and adopt electrolysis oil of mirbane to prepare the technology of p-aminophenol.
Background technology
P-aminophenol (PAP) is a kind of application fine-chemical intermediate very widely, is mainly used in medicine, dyestuff, rubber, feed, oil and photographic industry etc.The p-aminophenol production method has p-NP iron powder reducing method and catalytic hydrogenating reduction method, oil of mirbane catalytic hydrogenating reduction method and electrolytic reduction etc.
The characteristics of p-NP iron powder reducing method have, and 1. are relatively classic methods, technology maturation, and technology is simple; 2. product yield is low, and is second-rate, needs through refining; 3. generation contains phenol in a large number and contains amine iron mud and sewage in the production process, administers difficulty, pollutes very serious; 4. production process is more, the energy consumption height.Therefore China determines no longer to enlarge already.Though p-NP catalytic hydrogenating reduction method pollution condition is lighter, because p-NP cost of material height, hydrogenation pressure height, and Preparation of Catalyst complexity cost an arm and a leg, and reclaim difficulty, are unfavorable for suitability for industrialized production.
The continuous rising of PAP consumption and the formulation of Law on Environmental Protection have promoted the improvement of PAP production technique and the exploitation of novel method.In recent years, great majority are raw material with oil of mirbane both at home and abroad, adopt hydrogenation or electrolytic reduction method to prepare p-aminophenol.United States Patent (USP) 3383416,4307249,4264529, Chinese patent CN103667B, CN1237575A, CN1087623A etc. all relate to oil of mirbane catalytic hydrogenating reduction legal system and are equipped with p-aminophenol.The key problem in technology of this method has and 1. prevents deep hydrogenation, and nearly all patent is all mentioned the problem that prevents deep hydrogenation, and it is that to influence PAP one of optionally crucial; 2. the input speed of oil of mirbane, input speed is relevant with reaction conditions to a great extent, and is promptly relevant, particularly closely related with hydrogen pressure with catalyst activity, stirring condition etc.; 3. the selection of tensio-active agent and consumption, tensio-active agent can not only increase the solubleness of oil of mirbane in medium, and it still is a kind of promotor.Have advantages such as selectivity is good, energy utilization rate is high, free from environmental pollution owing to produce p-aminophenol with electrolytic reduction oil of mirbane, and because production process is short, need not noble metal catalyst and pressurized operation, thereby become a kind of new technology that has superiority most in the PAP production method, cause Chinese scholars and entrepreneur's attention and interest.The report of this respect has United States Patent (USP) 3338806,5066369, Chinese patent 1061808 and 1050057 etc.United States Patent (USP) 3338806 is owing to add ethanol and sulfuric acid in catholyte, cause multiple production of by-products and make the yield of p-aminophenol have only 62%, and need to reclaim solvent, thereby increased production cost.Although United States Patent (USP) 5066369 and Chinese patent CN1050057 organic solvent useless or tensio-active agent increase the solubleness of reactant oil of mirbane, the negative electrode that has utilized multistage rotating electrode and electrolyte-electrode of solid polymer to form.The transmission of electricity of rotating electrode and the resistance of barrier film cause the bath voltage height, and power consumption is big.And electrolyte-electrode of solid polymer is a kind of novel electrolysis reactor, also is in conceptual phase, realizes that industrialization also will solve many difficult problems.
Summary of the invention
Thereby the objective of the invention is to disclose a kind of by adding oxidation inhibitor and prepare the method for p-aminophenol according to the oil of mirbane electrolytic reduction that the flow velocity that the change in concentration of p-aminophenol in the electrolytic process is in time adjusted current density and catholyte improves the p-aminophenol selectivity of electrolytic process and current efficiency in catholyte, the p-aminophenol yield that prior art exists is low to overcome, needs recovery solvent, defective that production cost is high.
Design of the present invention is such:
(1) solubleness of oil of mirbane raw material in solution is less.Mass transfer process becomes the controlled step of whole electrolytic process.Because not with an organic solvent as tensio-active agent, thereby oil of mirbane mass transfer velocity between sulfuric acid electrolyte and electrode is decided by the flow condition of catholyte.Improve flow velocity and not only can accelerate reactant oil of mirbane interphase mass transfer, and can accelerate the mass transfer of intermediate product phenylhydroxylamine.Experimental studies have found that in electrolytic different steps electrolyte flow rate is different to the influence of electrolysis effectiveness.Consider that from the electrolysis energy consumption of electrolytic process and the whole angle of power consumption the flow velocity of electrolytic solution should change according to the variation of the variation of p-aminophenol content and content of by-products and other electrolytic conditions in the electrolytic process.
(2) content owing to p-aminophenol in the electrolytic process changes always, and is very high at electrolysis later stage p-aminophenol content.Thereby improve the chemo-selective of p-aminophenol for the generation that improves current efficiency and minimizing side reaction, be necessary to adopt the electrolysis mode of time-dependent current density according to the content of p-aminophenol in the electrolytic solution, be to adopt bigger current density the electrolysis initial stage, and adopt less current density when the electrolysis later stage, p-aminophenol content was very high.
(3) because the principal product p-aminophenol is easy in electrolytic process and the later separation purification process in oxidized dose of (mainly being airborne oxygen) oxidation, and adopt the mode of logical nitrogen deoxygenation to stop p-aminophenol oxidized fully, and operate uneconomical.Therefore the present invention stops p-aminophenol oxidized by the mode that adds oxidation inhibitor in catholyte.
According to above-mentioned design, the present invention proposes technical scheme as described below, to reach the purpose that the present invention will realize.
The said method of the present invention comprises the steps:
(1) the oil of mirbane electrolytic reduction prepares p-aminophenol:
At first oil of mirbane, sulfuric acid are dropped in the dissolving tank, form catholyte, oil of mirbane can add continuously or add in batches, guarantees that nitrobenzene solution is in saturated or near state of saturation all the time, with the catholyte recycle pump catholyte is sent into electrolyzer then and react, its main reaction formula is:
Side reaction mainly contains:
The catholyte of the p-aminophenol that containing responds generates is sent back to dissolving tank, with be admitted to electrolyzer again after saturated nitrobenzene solution mixes and carry out electrolysis, so repeatedly circulation, the concentration of p-aminophenol reaches the requirement of process stipulation in reaction product, is generally 9%～10% mass percent;
Temperature, anolyte composition, cathode material and anode material etc. used in the electrolytic process all can be with reference to relevant patents.
The current efficiency and the p-aminophenol of electrolytic process optionally are defined as:
The electric weight of current efficiency=theoretical electric weight/generation unit mole p-aminophenol actual consumption that generation unit mole p-aminophenol consumes,
The oil of mirbane amount (mol) of the growing amount of p-aminophenol selectivity=p-aminophenol (mol)/consumption.
The change in flow scope of catholyte is 0.01～1.0 meter per second, and better scope is 0.1～0.4 meter per second.According to the conception of front, can improve raw material and the rate of mass transfer of intermediate phenylhydroxylamine between liquid-solid phase to greatest extent by the flow condition that improves catholyte.If the catholyte flow velocity remains unchanged in whole electrolytic process, it all is uneconomic getting flow rate control higher so or hanging down.On negative electrode, continued reduction because flow velocity is crossed the low intermediate phenylhydroxylamine that will cause, and flow velocity is crossed the low mass transfer that also will be unfavorable for oil of mirbane; If flow velocity is too high, the energy consumption of power system will increase so, and can not improve the mass transfer velocity of oil of mirbane significantly at excessive flow velocity of electrolysis initial stage.According to solubleness, p-aminophenol content and other electrolytic conditions of oil of mirbane in the electrolytic process, the present invention adopts unsteady flow speed scheme in whole electrolytic process, i.e. electrolysis catholyte flow velocity in early stage is lower, and electrolysis later stage electrolyte flow rate is higher.So both can guarantee that material at two alternate rate of mass transfer, can reduce the energy consumption of power system again.Therefore, electrolyte flow rate preferably changes by p-aminophenol concentration in the electrolytic solution in the electrolytic process:
P-aminophenol concentration flow velocity in the catholyte
0～50g/L, 0.1 meter per second
50g/L～100g/L 0.4 meter per second.
Similarly, the current density change scope is 500～3500 amperes per meter in the electrolytic process
2, better variation range is 800～2500 amperes per meter
2Because the content of p-aminophenol all changes in the electrolytic process always.Electrolysis initial stage p-aminophenol content is very low and later stage p-aminophenol content is very high.For thereby the generation that improves current efficiency and minimizing side reaction improves the selectivity of p-aminophenol and the throughput that improves electrolyzer as much as possible, be necessary to adopt the electrolysis mode of time-dependent current density, be to adopt bigger current density the electrolysis initial stage, and adopt less current density when the electrolysis later stage, p-aminophenol content was very high.Preferably carry out electrolysis as follows:
P-aminophenol concentration in the catholyte: 0～80g/L I amperes per meter
2
P-aminophenol concentration in the catholyte: 80g/L～100g/L α I ampere per meter
2, α gets 0.3-0.9, and optimum value is 0.618.
In the following formula, I=1500～2000 amperes per meter
2
According to the present invention, can in catholyte, add an amount of oxidation inhibitor such as sodium bisulfite, S-WAT or (with) vat powder etc.P-aminophenol in electrolytic process and later separation purification process all very easily by air be dissolved in dioxygen oxidation in the catholyte.Owing in electrolytic process, separates and leads to the nitrogen deoxygenation in the purification process to reach the effect of protecting p-aminophenol be not unusual ideal with follow-up head product.Because taking dissolved oil of mirbane out of catholyte, nitrogen causes oil of mirbane loss and environmental pollution in the catholyte.Just in catholyte, add oxidation inhibitor when electrolysis begins and to guarantee that not only p-aminophenol is not oxidized in the electrolytic process, and can guarantee that p-aminophenol is not oxidized in operations such as follow-up neutralization, extraction, decolouring, crystallization.Existing technology is to add oxidation inhibitor when decolouring.Present method is that oxidation inhibitor is added in the reactor, makes to prevent in the whole process of production that p-aminophenol is oxidized.The add-on of oxidation inhibitor is generally 0.05～0.1%.
(2) separation of p-aminophenol head product is purified
The above-mentioned catholyte that contains p-aminophenol adopts conventional means of cell operation such as neutralization, extraction, decolouring, crystallization and drying to separate and purifying, can obtain 98.5% p-aminophenyl phenolic product.Specifically can be with reference to relevant patent, the present invention repeats no more.
By above-mentioned invention disclosed content as seen, method p-aminophenol yield height of the present invention does not need to reclaim solvent, and production cost is low, is easy to industrializing implementation.
Description of drawings
Fig. 1 is a process flow sheet.
Wherein:
1-cathode dissolution groove 2-catholyte recycle pump
3-heat exchanger 4-electrolyzer
5-cationic exchange membrane 6-negative electrode
7-anode 8-anolyte recycle pump
9-aftertreatment device 10-anode liquid bath
Embodiment
As seen from Figure 1, at first oil of mirbane, sulfuric acid are dropped in the dissolving tank 1, form catholyte, oil of mirbane can disposable whole addings, also can regularly add in batches, with catholyte recycle pump 2 catholyte is sent into electrolyzer 4 then and carry out electrolytic reaction, catholyte goes out electrolyzer 4 after be admitted to electrolyzer 1 after heat exchanger 3 heating, with be admitted to electrolyzer 4 again after oversaturated cathode solution is mixed and carry out electrolytic reaction, after the concentration of p-aminophenol reaches 90g/L～100g/L in catholyte, be sent to follow up device 9 and handle.The current density of whole electrolytic process from high to low, and the flow velocity of catholyte changes from low to high, preferably adopts above-mentioned current density and electrolyte flow rate Changing Pattern to carry out electrolysis.
Anolyte can carry out circulation between electrolyzer 4 and anode liquid bath 10 by anolyte recycle pump 8, and negative electrode 6, anode 7 and cationic exchange membrane 5 all can be determined according to prior art.
Adopt said process to prepare p-aminophenol, current efficiency can reach more than 85%, and the p-aminophenol chemo-selective can reach more than 90%.This method compared with prior art, the power system energy consumption of oil of mirbane cathode reduction process is less, current efficiency and p-aminophenol selectivity height, simultaneously owing to when electrolysis begins, just there is oxidation inhibitor in the catholyte, thereby the p-aminophenol that reaction generates in the electrolytic process is not oxidized, and follow-up neutralization, decolouring etc. to separate in the purification operations process p-aminophenol also not oxidized, therefore, production cost is lower, and the process productive rate is higher.
Below will be described further the specific embodiment of the invention by embodiment.
Embodiment 1
All percentage compositions among the embodiment are the quality percentage composition.
Electric tank cathode is a copper mesh, and thickness is 20mm, and anode is plumbous, and barrier film is a HF-1 type cationic membrane, and catholyte is 18% sulfuric acid and oil of mirbane, and anolyte is 18% sulfuric acid.With magnetic drive pump electrolytic solution is carried out cyclical operation, the electrolyzer inlet temperature is 90 ℃, 85 ℃ of temperature outs, and current density and catholyte change in flow rule are as follows:
P-aminophenol concentration: 0～80g/L 2500 ampere per meters in the catholyte
2
P-aminophenol concentration: 80g/L～100g/L 1500 ampere per meters in the catholyte
2
P-aminophenol concentration: 0～50g/L 0.1 meter per second in the catholyte;
P-aminophenol concentration: 50g/L～100g/L 0.4 meter per second in the catholyte.
After electrolysis finishes, the consisting of of catholyte: p-aminophenol 100g/L, oil of mirbane 5g/L, aniline 10g/L, the current efficiency 85% of this process, p-aminophenol chemo-selective 90%.
Adopt device and the cathode and anode electrolytic solution identical with embodiment 1, specifically electrolysis mode is:
P-aminophenol concentration: 0～70g/L 1500 amperes per meter in the catholyte
2
P-aminophenol concentration: 0～70g/L 0.1 meter per second in the catholyte;
After electrolysis finishes, the consisting of of catholyte: p-aminophenol 70g/L, oil of mirbane 5g/L, aniline 30g/L, the current efficiency 60% of this process, p-aminophenol chemo-selective 70%.
Claims (5)
1. an oil of mirbane electrolytic reduction prepares the method for p-aminophenol, it is characterized in that this method comprises the steps:
The catholyte of saturated oil of mirbane, sulfuric acid and oxidation inhibitor composition is sent into electrolyzer react, the change in flow scope of catholyte is 0.01～1.0 meter per second, and the current density change scope is 500～3500 amperes per meter in the electrolytic process
2
Wherein: the flow velocity of p-aminophenol concentration catholyte in the catholyte
0～50g/L, 0.1 meter per second
50g/L～100g/L 0.4 meter per second;
P-aminophenol concentration current density in the catholyte
0～80g/L I amperes per meter
2
80g/L～100g/L α I ampere per meter
2
α is 0.3～0.9 in the formula, I=1500～2000 amperes per meter
2
2. the method for claim 1 is characterized in that, the change in flow scope of catholyte is 0.1～0.4 meter per second in the electrolytic process, and the current density change scope is 800～2500 amperes per meter
2
3. method as claimed in claim 2 is characterized in that, wherein oxidation inhibitor is sodium bisulfite, S-WAT or/and vat powder, and its add-on is 0.05～0.1% of an oil of mirbane weight.
4. method as claimed in claim 3 is characterized in that, wherein α is 0.618.
5. as described any one method of claim 1～4, it is characterized in that the catholyte of the p-aminophenol that containing responds generates is sent back to dissolving tank, and be admitted to electrolyzer again after saturated nitrobenzene solution mixes and carry out electrolysis, repeatedly circulate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011133147A CN1142325C (en) | 2001-07-10 | 2001-07-10 | Process for preparing p-aminophenol by electrolytic reduction of nitrobenzene |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011133147A CN1142325C (en) | 2001-07-10 | 2001-07-10 | Process for preparing p-aminophenol by electrolytic reduction of nitrobenzene |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1342785A CN1342785A (en) | 2002-04-03 |
| CN1142325C true CN1142325C (en) | 2004-03-17 |
Family
ID=4660049
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB011133147A Expired - Fee Related CN1142325C (en) | 2001-07-10 | 2001-07-10 | Process for preparing p-aminophenol by electrolytic reduction of nitrobenzene |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1142325C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100529190C (en) * | 2006-11-03 | 2009-08-19 | 华东理工大学 | O-nitrophenol electrolyzing reduction process for preparing O-aminophenol |
-
2001
- 2001-07-10 CN CNB011133147A patent/CN1142325C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1342785A (en) | 2002-04-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111254456B (en) | Electrochemical synthesis method of 2-nitro-4-methylsulfonylbenzoic acid | |
| CN1076735A (en) | Cerium is that the indirect electrochemical of media is synthetic | |
| CN111472016A (en) | Method for preparing hydrogen peroxide by electrolyzing and recovering sodium sulfate waste liquid | |
| CN114606518B (en) | Method for generating ethylene by electrochemical acetylene selective hydrogenation | |
| CN113373464B (en) | Method for preparing cyclane by electrocatalytic conversion of lignin derivative | |
| CN1142325C (en) | Process for preparing p-aminophenol by electrolytic reduction of nitrobenzene | |
| CN106987862A (en) | A kind of method of the electrochemical degradation lignin in eutectic solvent | |
| CN101591787A (en) | A kind of electrochemical method for synthesizing of atoxylate | |
| CN1247819C (en) | Paired electrolysis procss of preparing glyoxalic acid | |
| JPH0730475B2 (en) | Method for producing 1-aminoanthraquinones | |
| CN1137288C (en) | Oxalic acid electroreduction process of preparing glyoxalic acid | |
| CN113621983B (en) | Method for preparing sebacate compound through anodic decarboxylation oxidative coupling | |
| CN114917952A (en) | Preparation method of intermediate catalyst for preparing hexamethylene diamine from caprolactam | |
| CN1141418C (en) | Process for preparing glyoxylic acid by electrolytic reduction of oxalic acid | |
| CN112226782A (en) | Refining process of solid sodium methoxide | |
| CN101096334B (en) | Method for reclaiming oxidation sludge of terephthalic acid prepared by dimethylbenzene | |
| CN1341779A (en) | Method for preparing hypophosphorous acid by using electrolytic method | |
| CN1308598A (en) | Process for the isolation of aromatic hydroxycarboxylic acids | |
| CN219752008U (en) | Anti-pollution and anti-scaling waste salt solution utilization device | |
| CN112593255B (en) | Electrochemical preparation method of p-aminophenyl-beta-hydroxyethyl sulfone | |
| CN117867532A (en) | Method for synthesizing p-aminophenol and application thereof | |
| CN1436877A (en) | Paired 2,3,6-trimethyl phenol electrolyzing process of preparing 2,3,5-trimethyl hydroquinone | |
| CN1641071A (en) | Alkyl hydroxylamine and its salt electrochemical synthesis method | |
| CN114656319B (en) | Preparation method of high-purity dicyclopentadiene | |
| CN108796547B (en) | Electrochemical regeneration method of chloranil by taking halogen ions as electrocatalyst |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |