CN101544567A - Nitration method for synthesizing dinitrotoluene in one step, and microchannel reactor - Google Patents
Nitration method for synthesizing dinitrotoluene in one step, and microchannel reactor Download PDFInfo
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- CN101544567A CN101544567A CN200810010797A CN200810010797A CN101544567A CN 101544567 A CN101544567 A CN 101544567A CN 200810010797 A CN200810010797 A CN 200810010797A CN 200810010797 A CN200810010797 A CN 200810010797A CN 101544567 A CN101544567 A CN 101544567A
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Abstract
The invention relates to one-step dinitrotoluene synthesis in a microchannel reactor. The method comprises the steps of taking toluene and mixed acid of nitric acid/sulfuric acid (n/s) as initial reaction materials, inputting material flow synchronously into a microreactor through a metering pump and finishing mixed mass transfer and reaction in a reaction channel. The substance ratio of n to s in the reactive mixed acid is 0.1 to 1.0, and the mass ratio of water is less than 15 percent. The liquid hourly space velocity in the reactor is 500 to 50,000 h<-1>. The microchannel reactor adopts a stainless steel flat-plate structure which comprises fixed pressing-sealing plates, a microchannel plate, a raw-material inlet, a product outlet, as well as a temperature-control pore channel and a thermal-couple measurement-control jack which are positioned on two sealing plates. The method is continuously operated under a technological condition with medium/strong nitrating acid, and is safe in process. The conversion rate of the toluene in the reactor at an operation temperature between normal temperature and 80 DEG C is higher than 98 percent, and the yield of dinitrotoluene is higher than 95 percent, wherein the ratio of two main isomer components, namely 2,4-dinitrotoluene and 2,6-dinitrotoluene, is more than 4 and can be nearly 5 under optimum conditions.
Description
Technical field
The present invention relates to aromatic nitration, specifically the nitrifying method of synthesizing dinitrotoluene in one step and micro passage reaction are toluene one-step synthesizing dinitrotoluenes in micro passage reaction; It can under strong nitrating acid and normal temperature to the 80 ℃ reactor condition, safe and continuous synthesizing dinitrotoluene in micro passage reaction, wherein the design of micro passage reaction and application belong to new chemical reactor field.
Background technology
Methylbenzene nitration is important reaction in the chemical industry, and its nitration product dinitrotoluene (DNT) (DNT) is mainly used in the preparation of dyestuff, paint, coating, also is the precursor of producing explosive and tolylene diisocyanate (TDI).Conventional industrial production DNT method is to use the stirring reaction system of many ring types or many cooking-pot type serial or parallel connections, toluene and nitration mixture are reacted under constant temperature or adiabatic condition, constant temperature helps selectivity of product, adiabatic condition can make reaction concentrate with spent acid and integrate, play the effect of cutting down the consumption of energy, use single stage method and two-step process existing report in lot of documents of cooking-pot type reactor.
Toluene two nitration processes are representative with exploitations such as Bayer A.G's Florian Kringe and Di Te Ritchie, at patent (the EP 95111993A of Klingler; EP 96108857A; CN 1121506A, 1996; CN 1142486A, 1997; US 5689018,1997; The directly synthetic DNT technology of employing two-step approach synthesis technique and single stage method is disclosed US6258986,2001); The two-step approach of Klingler is taked the nitrated adiabatic nitration again of first isothermal route, and single stage method is a raw material with 70～100% mononitrotoluenes (MNT) in adiabatic process, and the main source of mononitrotoluene still is a methylbenzene nitration in fact.Klingler technology is nitrating agent with the nitric-sulfuric acid, 80～100% is sour phase in its raw material, 0～20% is organic phase, wherein contain 60～90% sulfuric acid (mass concentration) in the acid mutually, 1～20% nitric acid reaches at least 5% water, contain about 70～100%, 0～140 ℃ of down reaction of MNT in the organic phase, through separate, water 5% or more is removed in flash distillation, add the concentrated retrieval system of nitric acid.(CN1523006A, 2004) such as the special Ritchies of E enlightening take two-step approach to prepare technology equally, the first step adiabatic nitration, this moment toluene conversion greater than 90%, the DNT selectivity is less than 70%, through separation, flash concentration, organic phase entered for second step respectively mutually with acid, carried out isothermal reaction again.Single stage method and two-step process all allow to generate the MNT of different amounts in reaction product, can avoid the crystallization of DNT in concentration process and cause the heat exchanger obstruction.
(US 5354924 for Robert W etc., 1994) the synthetic DNT of single stage method in the bipolarity inert solvent, be reflected in the homogeneous phase and carry out, nitric acid and toluene mole ratio are up to 10～15:1 in this patent, and nitration mixture still is anhydrous (〉 95wt%) nitric-sulfuric acid, thereby be fuming serious and product is separated into and is difficult point.
CN 1793106A (2006) adopts the placed in-line two-step approach isothermal reaction of 8 stills technology, obtain dinitrotoluene (DNT) concentration greater than 95.3%, and do not have MNT and TNT, but reactor progression is many, employing has the reactor of paddle formula agitator, and the security of reaction process is difficult to ensure.
To sum up, for strong heat release toluene two nitrated fast responses, adopt still formula or cooking-pot type reactor, require gentle relatively sour condition to reduce intrinsic speed, itself and reactor rate of heat transfer are complementary, so common process need many reactors in series so that toluene transforms the equipment bulky complex fully; Require organic phase and acid to press the specified proportion allotment mutually, and keep enough residence time of material, with control speed of reaction and rate of heat transfer; Need through generating the pilot process of mononitrotoluene; Need refrigeration plant (as guide shell) to take away a large amount of reaction heat rapidly, avoid focus to emerge and cause temperature runaway, set off an explosion.
Little reaction technology is to rise a kind of phase early 1990s, is modern chemical industry subject forward position, integrates MEMS (micro electro mechanical system) design philosophy and chemical ultimate principle, transplants unicircuit and is a kind of new and high technology of transmitter manufacturing technology.Because the characteristic dimension microminiaturization, the more conventional yardstick equipment of caloic transfer rate improves 1～3 order of magnitude between fluid.Little reaction technology has the advantage of many intrinsic, uniqueness: high rate of mass transfer; Directly amplify (modular structure, the parallel amplification) fast; Intrinsic safety and process are controlled; Process is continuously with highly integrated; Disperse and flexible production.
Particularly for strong heat release nitration reaction, the characteristics of the high caloic transfer rate of microreactor have the incomparable advantage of traditional reactor.In microreactor, carry out the methylbenzene nitration synthesizing dinitrotoluene and yet there are no report.
At U.S.Pat.No.6, the nitration reaction in the static micro mixer is disclosed in 861,527 (2005), prepare 8-NO with four hydration isoquinoline 99.9
2-N-COO-four hydration isoquinoline 99.9 adopt the nitrated again route of first carbonylation, and system can reach equilibrium state fast, and can obtain stable product yield; Be example also in the document, draw all nitration reactions that to carry out sediment-free matter in the micro-system with benzene and methylbenzene nitration.But this patent is not implemented toluene two nitrated reactions, and it is that the polyfluortetraethylene pipe of 0.25mm, long 80cm constitutes that described little reactive system connects an internal diameter by static mixer, so its static mixer only plays the pre-mixing effect, the essence reaction is carried out in kapillary, this reaction time reaches 7.85 minutes, with residence time of traditional continuous nitrification technology a magnitude.
J.R.Burns (US 7032607 B2,2006) introduced the contact method of a kind of distributed capillary reactor and immiscible two-phase fluid, and in its described reactor, implemented the reaction of benzene and toluene mono-nitration, confirm that capillary reactor is than popular response utensil competitive superiority, but in its described microreactor, do not implement toluene two nitrated reactions yet, when the benzene nitration reaction in the kapillary of 178 μ m was 90 ℃ of 24 seconds, temperature of reaction when the residence time, the benzene transformation efficiency only was 94%.
Angle from the per pass conversion and the product selectivity of reactor, more than its production cost of method of synthesizing dinitrotoluene described in the disclosed patent all be expensive, because reactor progression many (being called cascade reactor), the strict control of material rate, whipping appts and cooling system require and the machine of stopping of reactive system acts in agreement, local temperature rise is serious, reaction times is longer in addition, and the medium that has DNT or comprise most of DNT stands the problem of high temperature stress, and equipment coexists with the operation insecurity.
Summary of the invention
The object of the present invention is to provide a kind of micro passage reaction technology of utilizing, can or be higher than the reactor operating condition of normal temperature at normal temperature, need not whipping process, need not many reactors in series combinations, just can obtain the continuous preparation technology of single stage method of the process safety of high conversion, highly selective dinitrotoluene (DNT).
The present invention in micro passage reaction single stage method by the direct synthesizing dinitrotoluene of toluene, and employing improves the rapid reaction technology of nitration reaction intrinsic speed of reaction, can significantly improve the selectivity of toluene two nitrated speed of response and two nitrated product D NT, improve the space time yield of target product, eliminate the potential safety hazard of toluene two nitrated processes.
For achieving the above object, the technical solution used in the present invention is:
The nitrifying method of synthesizing dinitrotoluene in one step reacts in the microreactor that has two imports and an outlet, comprises following technical characterictic:
1) be nitrating agent with nitric acid and vitriolic mixing acid, wherein nitric acid and vitriolic mol ratio are 0.1～1, and the mass concentration of water is lower than 15wt% in the nitration mixture;
2) two bursts of streams of reaction mass mixing acid and toluene are gone into via the volume pump synchronous pump in two imports of micro passage reaction, and the mol ratio of control nitric acid and toluene is 1.6～2.4;
3) after two strands of stock liquids contact in micro passage reaction, hybrid concurrency gives birth to reaction, flow out, enter separator from the exit of reactor; The liquid hourly space velocity LHSV of micro passage reaction is 500～50000h
-1
4) with reaction product standing demix, water phase separated and organic phase in the separator, organic phase is through washing, the dry product dinitrotoluene (DNT) that gets.
Product separates and the concentrated purification of water can be carried out by means of ordinary method and equipment, and aqueous phase is reusable after concentrating through dewatering and purifying.
Principal product DNT selectivity is greater than 95wt%, and material proportion and reactor service temperature can be,
1) nitration mixture nitre sulphur mol ratio 0.1～0.5, and quality concentration is lower than 5%, and charging nitric acid and toluene amount are than 2.0～2.4, and reactor normal temperature is operation down;
Or 2) nitration mixture nitre sulphur mol ratio 0.1～0.5, quality concentration 5～15%, charging nitric acid and toluene amount are than 2.0～2.4, and the reactor temperature control is operation (30～80 ℃) down;
Or 3) nitration mixture nitre sulphur mol ratio 0.5～1.0, quality concentration 5% and below, reaction raw materials nitric acid and toluene amount are than 2.0～2.4, the reactor temperature control is operated (30～80 ℃) down.
When containing the by product MNT of mass concentration below 20% in allowing product D NT, material proportion and reactor service temperature can be,
1) inlet amount of reaction raw materials nitric acid and toluene ratio is controlled at 1.6～2.0;
Or 2) nitric acid in the nitration mixture and sulfuric acid mol ratio are (0.5～1.0): 1; Reactor normal temperature is operation down;
Or 3) the quality concentration in the nitration mixture is greater than 5%.
Be used to realize the single pass reactor of above-mentioned synthetic method, comprise at least two substrates; Be arranged in wherein at least three microchannels of arbitrary substrate, i.e. at least two intake vents are with at least one reaction channel that links to each other with intake vent respectively; At least two imports that are connected with intake vent respectively, and an outlet that is connected with reaction channel.
Be used to realize the multi-channel reaction device of above-mentioned synthetic method, comprise at least two substrates and a slice microchannel plate; Be positioned at least three microchannels on the microchannel plate, i.e. at least two intake vents are with at least one reaction channel that links to each other with intake vent respectively; Intake vent links to each other with two imports respectively, and reaction channel links to each other with outlet; And at least one intake vent is colluded a side that is in microchannel plate with reaction.
Described two intake vents are in two sides of microchannel plate respectively; Described import microchannel can be consistent with the microchannel characteristic dimension, also can be different; Every intake vent can be provided with branch, and when intake vent was established the branch of one or more, branched bottom linked to each other with the higher level microchannel with arc-shaped structure, and the equivalent diameter size of microchannel can successively decrease step by step, and the amplitude of successively decreasing is 0-80%; Angle between at least two intake vents that link to each other with reaction channel can be arbitrarily angled, and the hydraulic diameter scope of reaction channel should be below 1mm; The microchannel length range is 0.2～50cm; Described reaction channel links to each other with outlet through exit passageway; Wherein intake vent adds that the distance of exit passageway accounts for 1/3～2/3 of total distance between import and outlet.
Angle between described at least two intake vents that link to each other with reaction channel is preferably 0～180 °; The hydraulic diameter of reaction channel is preferably in 0.1～0.5mm; The microchannel length range is preferably 2～20cm.
At least be respectively arranged with 1 bottoming hole and observing and controlling thermocouple jack on described two substrates; Be connected sealing or adopt vacuum diffusion welding to connect with stainless steel bolt between described substrate and the microchannel plate; Described reactor outlet connects separating device, or connects separating device after exit point chilling termination reaction.
The technology of the present invention's employing preparation dinitrotoluene (DNT) in microreactor compared with prior art has following advantage:
1. toluene and nitration mixture react direct synthesizing dinitrotoluene through single stage method, and the process safe and continuous;
2. two-phase mass transfer and reaction process are finished in little reaction channel, need not conventional whipping process, thereby simplify reactor structure, reduce power consumption;
3. reaction raw materials does not need to add solvent, avoids separating in the product preparation process step of solvent, has improved yield, saves Material Cost;
4. the flash heat transfer of micro passage reaction, mass transfer ability make reaction process be easy to realize that isothermal is nitrated, therefore, can adopt the rapid reaction technology that improves nitration reaction intrinsic speed of reaction to carry out nitration reaction in the microreactor.
In the microreactor residence time of material at millisecond to several seconds scopes, reaction can reach balance fast, selectivity of product can be stablized control; Under same substance amount proportioning, feed stock conversion and DNT selectivity in the microreactor of the present invention all are higher than popular response device or conventional cascade reactor.
In a word, the present invention in to carry out toluene two under the strong nitrating acid condition nitrated, the toluene per pass conversion is higher than 99%, the dinitrotoluene (DNT) yield is higher than 95%, two kinds of main isomer components 2 wherein, 4-dinitrotoluene (DNT) and 2, the ratio of 6-dinitrotoluene (DNT) can be near 5 under the optimal conditions greater than 4.
Description of drawings
Fig. 1 is a single pass reactor channel plate structural representation;
Fig. 2 is a multi-channel reaction device channel plate structural representation;
Fig. 3 is that embodiment 1 reaction mass air speed changes the figure that influences to reactivity worth;
Fig. 4 is that embodiment 2 reaction mass air speeds change the figure that influences to reactivity worth;
Fig. 5 is that embodiment 3 reaction mass air speeds change the figure that influences to reactivity worth;
Fig. 6 be in the mixed acid nitration quality concentration to the figure that influences of reactivity worth;
Fig. 7 is the figure that influences of nitric acid and toluene feed comparison reactivity worth.
In the described enforcement of Fig. 3 to Fig. 7, except that Fig. 5 adopted miniature single pass reactor (shown in the accompanying drawing 1), other reaction result all obtained in miniature multi-channel reactor (Fig. 2).
Embodiment
Be used to realize that single stage method is comprised by the device that toluene directly synthesizes DNT: two liquid constant-flux pumps, carry two kinds of immiscible reaction mass toluene and mixed acid nitration respectively, a core micro passage reaction, labwares such as the vial of some splendid attire raw materials and reaction product or beaker, stainless steel or PTFE pipe connecting are used for that raw material is imported reactor and the product logistics derives.
Micro passage reaction of the present invention comprises at least two substrates and a slice microchannel plate 5; Be positioned at least three microchannels on the microchannel plate 5, i.e. at least two intake vents 2 are with at least one reaction channel 3 that links to each other with intake vent 2 respectively; Intake vent 2 links to each other with two imports 1 respectively, and reaction channel 3 links to each other with outlet 4; Article two, intake vent 2 can be in two sides of microchannel plate respectively; Little reaction channel is taked single passage as shown in fig. 1, or as the hyperchannel among Fig. 2, ' T ' shape passage shown in Fig. 1 is positioned on the hypocoxa, immiscible toluene and nitrating acid enter intake vent simultaneously in two ingress that are arranged in upper substrate, enter the reaction channel that is 90 ° of angles with two intake vents then, and in reaction channel, finish and mix mass transfer and reaction process, comprise dinitrotoluene (DNT) and sour reaction product mutually in outflow of the exit of reaction channel and acquisition, the separation of reaction product can be carried out in equipment known in the art, or carry out by means of means known in the art, for example separate and can finish in the static separation device, spent acid concentrates can take the low pressure flash mode to finish.And the present invention is combined to technology and microreactor equipment for disclosing a kind of novel toluene dinitro, so product processing process adopts sharp separation to finish in the laboratory.
The reaction channel plate is a stainless steel sheet among Fig. 2, be clipped in the middle of two upper and lower base plates, in upper substrate, there are three raw materials corresponding to import and export with position, the circular gangway of Sptting plate, reaction raw materials toluene and mixed acid nitration are entered by two access roades respectively, one of them raw material is entered by channel plate one side entrance passage, another raw material is then entered by the channel plate opposite side, which side to enter intake vent by all be feasible to two kinds of raw materials in principle, consider from the resistance of two inlets, the raw material that flow is big is entered by the little side-entrance passage that is carved with reaction channel of pressure drop, and opposite side because of fluid repeatedly will be by the reaction channel front end after the shunting in intake vent a circular micro-through-hole (equivalent diameter is 0.1～0.5mm) to enter reaction channel, thereby the entrance friction of this side is larger than channel side, so what flow was little in two strands of raw materials enters reaction channel from this side, the processing power of reactor can improve like this.
Each side-entrance passage in the channel plate shown in Figure 2 is provided with 16 branches, (n is the intake vent branches also can be arranged to other number such as 2n, can be 0 i.e. branch not), link to each other with the semicircular arc microchannel between higher level microchannel and the subordinate microchannel, and the equivalent diameter size of microchannel is successively decreased step by step, the amplitude of successively decreasing is 50%, also can be decided at the higher level but not officially announced in 0～80% scope.Thereby raw material is distributed on to finish in 16 reaction channels and mixes mass transfer and reaction process, be equivalent to 16 tubular reactors and carry out two nitrated reactions synchronously, wherein the equivalent diameter of every reaction channel is 0.3mm, also can between 0.1～1.0mm, choose wantonly, every long 60mm of passage, or between 2～500mm, appoint and decide.
The used nitrating acid of the present invention is still based on nitric acid and vitriolic mixing acid, nitric acid and vitriolic mass concentration should be all greater than 85% in the nitration mixture, both mol ratios should be in 0.1～1.0 scope, when requiring principal product DNT concentration to be higher than 95%, nitre sulphur mol ratio preferably be controlled at 0.5 and below, and below the mass concentration 5% of water reaches in the nitration mixture, under such condition, nitrating acid has stronger nitrated ability, can improve nitration reaction speed, so reactor can be operated at normal temperature or a little less than under the normal temperature;
It is two nitrated that micro passage reaction can take strong nitrated ability acid condition to carry out at normal temperatures, and process safety.But can dissolve the organic composition of a great deal of under this processing condition in the reaction product acid mutually, for weakening the concentrated acid solvability, and guarantee that the DNT selectivity is more than 95%, the present invention proposes two methods: one can to use the nitrating acid of quality concentration 5～15% to carry out two nitrated, only reactor is implemented gentle temperature control state, can specifically be controlled at 30～80 ℃, when temperature surpasses 80 ℃, nitric acid may partly decompose in the intake vent of microreactor, nitrated ability reduces when causing nitration mixture to enter reaction channel, and the 2nd, in doing cold shock processing or product collection device, the reactor outlet point annotates proper amount of normal-temperature water.In allowing product the concentration of MNT 20% and below, then in whole described nitration mixture concentration, reaction is carried out at normal temperatures.
The fusing point of toluene one nitration product MNT is lower than DNT, thereby often allows retained part MNT in the product in conventional nitration processes, and the reaction product separation reaches when concentrating and just can avoid the DNT crystallization to cause the heat exchanger blocking problem like this.
MNT concentration is less than 10% or 20% the time in allowing product, three kinds of approach are arranged: one is to use strong nitrated ability acid, just the n/s value is 0.1～0.5 and moisturely is lower than 15% (quality), preferably be lower than 10%, and the charge ratio of control committed step material nitric acid and toluene is less than 2, but can not be less than 1.6, like this under identical nitration reaction speed, the mononitrotoluene that generates in the reaction process does not have enough available nitric acid to continue reaction generation dinitrotoluene (DNT), but toluene transforms fully or approaching conversion fully.The 2nd, keep nitric acid and toluene under the condition of equivalence ratio more than 2.0, increase concentration of nitric acid or water concentration, reduce the mixed acid nitrification ability, two nitrated speed of response are descended, in than short residence time(SRT), a nitrated intermediate product is difficult to continue fast nitrated one-tenth DNT.Water concentration will make the transformation efficiency of toluene and two nitrated speed descend rapidly in the nitration mixture but continue to increase, and the concentration of nitric acid increase can not make toluene conversion than fast-response.Thereby take to increase separately the concentration of nitric acid method, and the n/s value is between 0.5～1 in the nitrating acid specifically, and water concentration is lower than 15% (quality), preferably is lower than 10%.The 3rd, the quality concentration 5～15% in the nitration mixture.
Liquid hourly space velocity in the microreactor of the present invention is 500～50000h
-1Reaction mass nitric acid is controlled at 1.6～2.4 to the mol ratio of toluene, and under normal temperature, be pumped into two inlets of microreactor synchronously by volume pump, emphasize that here reaction mass must enter micro passage reaction synchronously, further reaction can not take place in the reaction product storage tank.The present invention confirms under optimal conditions, and when nitric acid and toluene mole ratio during in equivalence ratio 2, MNT has been less than 5% in the product, thereby the mol ratio of nitric acid and toluene is greater than 2.4 no technical meanings.
The present invention uses higher reaction velocity in reaction channel shown in Figure 1, generally speaking less than 50000h
-1, mainly be subject to the resistance drop of reactor; In multi-channel reaction device shown in Figure 2, use lower reaction velocity, between 500～10000h
-1Between, mainly being subject to the used volume pump range in laboratory, when breaking through this restriction, can under high-speed, operate equally in the multi-channel reaction device.
More than described the present invention, following examples confirm the invention process effect, and all percentage ratios are mass percent among the embodiment.
Nitric acid of the present invention is concentration greater than 65% nitric acid, and described sulfuric acid is concentration greater than 95% the vitriol oil, and described toluene is the industrial goods of content 〉=99%.
Adopt the anhydrous nitric acid (〉=98%) and the vitriol oil (〉 95%) prepare that nitric acid and sulfuric acid mol ratio are 0.3, water concentration is 2.87% nitration mixture.Controllable Temperature is built in below 35 ℃ in the preparation nitration mixture process.Under normal temperature condition, nitration mixture and toluene are continuously pumped into microreactor (reactor shown in Figure 2) by micro-constant-flux pump and react in little reaction channel.The mol ratio of control nitric acid and toluene is 2.0, the liquid hourly space velocity 600～2000h of reactor
-1The continuous outflow reactor of reaction product, and in separator static layering, tell acid solution, organic phase is washed, alkali cleaning and be washed to neutrality.Reaction result is seen accompanying drawing 3.The result of Fig. 3 shows that it is favourable to the transformation efficiency of toluene to implement to improve air speed under used micro passage reaction and the reaction conditions at this, but the DNT selectivity reduces; In the DNT isomer 2,4-DNT improves with air speed and reduces, and 2,6-DNT then increases.
Process and reactor used with embodiment 1 changes nitric acid and sulfuric acid mol ratio and is 0.5, nitric acid and toluene mole ratio be 2.15, and reactor normal-temperature operation, the liquid hourly space velocity in the reactor are 500～2000h
-1Result of implementation such as accompanying drawing 4 show.Compare with embodiment 1, concentration of nitric acid increases, and the DNT selectivity descends 11～17%, and the MNT selectivity then increases, and toluene conversion remains unchanged.
Process is with embodiment 1, and reactor uses ' T ' shape single passage structure microreactor shown in the accompanying drawing 1, and nitric acid and sulfuric acid mol ratio are 1.0, and quality concentration is 2.87% in the nitration mixture, and the mol ratio 2.45 of nitric acid and toluene is reflected at air speed 4000～50000h
-1In carry out.The methylbenzene nitration transforming degree is subjected to airspeed limitation hardly in result of implementation such as the accompanying drawing 5, microreactor, and reaction time is little to nitrated conversion influence, and toluene conversion is at air speed 52870h
-1Still can be under the condition up to 97.5%, at 40000h
-1In the wide air speed scope, principal product DNT selectivity obviously rises, and the MNT selectivity reduces.Two kinds of main isomer 2 of DNT, 4-DNT and 2, the ratio of 6-DNT does not almost change in described wide air speed scope, but with result among the embodiment 1 as seen, use the nitric-sulfuric acid of 1:1, the selectivity of MNT is up to 20%, 5.9% maximum among the embodiment 1 head and shoulders above, and 2,4-DNT/2,6-DNT ratio remains unchanged all between 4.35～4.9.
Process and reactor used with embodiment 1, change the water concentration in the mixed acid nitration, nitre sulphur is than constant, the metering ratio of fixation reaction air speed and nitric acid and toluene, this enforcement be in the examination raw material in the inorganic phase nitration mixture water concentration to the action intensity of toluene two nitrated reactions, reaction conditions and result of implementation are seen accompanying drawing 6, promptly under reactor is in normal temperature condition, when the mass concentration of water in the nitrating acid greater than 5% the time, nitrated product MNT in the DNT product increases sharply, raw water has produced the inhibition influence to dinitrated speed of reaction, but in described water concentration scope, a nitrated speed of reaction is not produced inhibition, to DNT isomer 2,4-DNT and 2, the proportionlity between the 6-DNT does not have obvious influence.
Process and reactor used with embodiment 1 changes the metered proportions relation of raw material nitric acid and toluene, keeps that nitre sulphur ratio is 0.3, water 2.87wt%, liquid hourly space velocity be 1150h
-1, result of implementation is seen accompanying drawing 7.The result shows, when the nitric acid amount is lower than dinitrated metering than 2 the time, understands some toluene and only is converted into MNT, and be equal to or slightly greater than metering than 2 the time when the nitric acid amount, has to surpass 94.5% toluene and change into two nitrated product D NT.
Although in above illustrating, stated the present invention and result of implementation thereof in detail; but be to be understood that; described details only is used to illustrate; this area professional and technical personnel is in the disclosed technical scope of the present invention; can understand conversion or the replacement expected; all should be encompassed in of the present invention comprising within the scope, therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.
Claims (10)
1. the nitrifying method of synthesizing dinitrotoluene in one step reacts in the micro passage reaction that has two imports and an outlet, it is characterized in that:
1) be nitrating agent with nitric acid and vitriolic mixing acid, wherein nitric acid and vitriolic mol ratio are 0.1～1, the mass concentration of water＜15% in the nitration mixture;
2) two bursts of streams of reaction mass mixing acid and toluene are gone into via the volume pump synchronous pump in two imports of micro passage reaction, and the mol ratio of control nitric acid and toluene is 1.6～2.4;
3) after two strands of stock liquids contact in micro passage reaction, hybrid concurrency gives birth to reaction, flow out, enter separator from the exit of reactor; The liquid hourly space velocity LHSV of micro passage reaction is 500～50000h-1;
4) with reaction product standing demix, water phase separated and organic phase in the separator, organic phase is through washing, the dry product dinitrotoluene (DNT) that gets.
2. according to the described synthetic method of claim 1, it is characterized in that: product separates and water concentrates purification and can carry out by means of ordinary method and equipment, water dewater concentrate after purifying reusable.
3. according to the described synthetic method of claim 1, it is characterized in that: principal product dinitrotoluene (DNT) selectivity can be greater than charge ratio and the reactor service temperature of 95wt%,
1) nitration mixture nitre sulphur mol ratio 0.1～0.5, quality concentration 5% and below, charging nitric acid and toluene amount are than 2.0～2.4, reactor normal temperature is operated down;
Or 2) nitration mixture nitre sulphur mol ratio 0.1～0.5, quality concentration 5～15%, charging nitric acid and toluene amount be than 2.0～2.4,30～80 ℃ of the operations down of reactor temperature control;
Or 3) nitration mixture nitre sulphur mol ratio 0.5～1.0, quality concentration 5% and below, charging nitric acid and toluene amount are than 2.0～2.4, the reactor temperature control is operated 30～80 ℃ down.
4. according to the described synthetic method of claim 1, it is characterized in that: when containing the MNT by product below the concentration 20wt% in allowing the dinitrotoluene (DNT) product, charge ratio and reactor service temperature can be,
1) charging nitric acid is controlled at 1.6～2.0 with the amount ratio of toluene;
Or 2) nitric acid and sulfuric acid mol ratio are 0.5～1.0:1 in the nitration mixture; Reactor normal temperature is operation down;
Or 3) in the nitration mixture quality concentration greater than 5%; Reactor normal temperature is operation down.
5. a micro passage reaction that is used to realize the described synthetic method of claim 1 is characterized in that: comprise two substrates at least;
Be arranged in wherein at least three microchannels of arbitrary substrate, i.e. at least two intake vents are with at least one reaction channel that links to each other with intake vent respectively; At least two imports that are connected with intake vent respectively, and an outlet that is connected with reaction channel.
6. a micro passage reaction that is used to realize the described synthetic method of claim 1 is characterized in that: comprise two substrates and a slice microchannel plate at least;
Be positioned at least three microchannels on the microchannel plate, i.e. at least two intake vents are with at least one reaction channel that links to each other with intake vent respectively; Intake vent links to each other with two imports respectively, and reaction channel links to each other with outlet; And at least one intake vent is colluded a side that is in microchannel plate with reaction.
7. according to the described micro passage reaction of claim 6, it is characterized in that: described two intake vents are in two sides of microchannel plate respectively.
8. according to claim 5 or 6 described micro passage reactions, it is characterized in that: described import microchannel can be consistent with the microchannel characteristic dimension, also can be different; Every intake vent can be provided with branch, and when intake vent was established the branch of one or more, branched bottom linked to each other with the higher level microchannel with arc-shaped structure, and the equivalent diameter size of microchannel can successively decrease step by step, and the amplitude of successively decreasing is 0-80%; Angle between at least two intake vents that link to each other with reaction channel can be arbitrarily angled, and the hydraulic diameter scope of reaction channel should be below 1mm; The microchannel length range is 0.2～50cm; Described reaction channel links to each other with outlet through exit passageway; Wherein intake vent adds that the distance of exit passageway accounts for 1/3～2/3 of total distance between import and outlet.
9. according to claim 7 and 8 described micro passage reactions, it is characterized in that: the angle between described at least two intake vents that link to each other with reaction channel is 0～180 °; The hydraulic diameter of reaction channel is 0.1～0.5mm; Microchannel length is 2～20cm.
10. according to claim 5 or 6 described micro passage reactions, it is characterized in that: be respectively arranged with 1 bottoming hole and observing and controlling thermocouple jack on described two substrates at least; Be connected sealing or adopt vacuum diffusion welding to connect with stainless steel bolt between described substrate and the microchannel plate; Described reactor outlet connects separating device, or connects separating device after exit point chilling termination reaction.
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