CN102731300A - Industrialization method for producing dimethyl oxalate by continuous cycle esterification and coupling carbonylation - Google Patents
Industrialization method for producing dimethyl oxalate by continuous cycle esterification and coupling carbonylation Download PDFInfo
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Abstract
The invention relates to an industrialization method for producing dimethyl oxalate by continuous cycle esterification and coupling carbonylation. The method comprises steps of, (1), esterification reaction, wherein methanol, O2 and nitrogen oxides enter a reaction zone of an esterification reaction tower in a concurrent flow and a reaction is carried out to generate methyl nitrite; liquid flow generated after the reaction flows out from a bottom outlet of the esterification reaction tower and cycles back to the reaction zone of the esterification reaction tower; a gas flow generated after the reaction flows out from the bottom outlet of the esterification reaction tower, and methyl nitrite is obtained by purification and dry; the esterification reaction tower is a packed column; (2), CO carbonyl synthesis reactor, wherein CO and methyl nitrite obtained in step (1) perform coupling reaction in a carbonyl synthesis reactor and generate dimethyl oxalate, and regenerate NO; and NO returns to the esterification reaction tower in step (1). By employing the method, a small factory investment, a stable device operation and a high selectivity of generating methyl nitrite by oxidation reaction and esterification reaction are guaranteed.
Description
Technical field
The present invention relates to a kind of continuous circulating esterification and oxo process dimethyl oxalate technology, specifically, relating to a kind of is that raw material oxidative carbonylation coupling joins the industrialization process method of producing dimethyl oxalate through CO.
Background technology
It is a kind of known chemical reaction that CO oxidative carbonylation coupling joins the generation dimethyl oxalate.Through introducing methyl nitrite as strong oxidizer, at Pd/Al
2O
3Under the catalyzer, CO generates dimethyl oxalate with methyl nitrite generation carbonylation coupled reaction under suitable temperature and reaction pressure condition, and the NO that regenerates.Dimethyl oxalate is not only and is used for the raw material sources that hydrolysis prepares the tool competition of oxalic acid, and prior and maximum purposes is to be used for hydrogenating materials to prepare terepthaloyl moietie, has extremely important business development using value.
CO oxidative carbonylation coupling joins some other process method embodiments that generate dimethyl oxalate and can find among disclosed Chinese patent CN 101190884A, CN 101475472A, the CN 101462961A in recent years, and these documents are enumerated at this as a reference.
The formation reaction of methyl nitrite is defined as regenerative response in this technical process, generally can realize through a reaction fractionating tower is set on stream.Regenerative response is easy to carry out, and does not need catalyzer, and reaction conditions is gentle.The preparation of methyl nitrite (MN, Methyl Nitrite), main reaction is:
Side reaction: CH
3OH+N
2O
4→ CH
3ONO+HNO
3
3N
2O
3+H
2O(g)→2HNO
3+4NO
The principal reaction thing is methyl alcohol, NO and O in the regeneration reaction system
2Owing to have NO and O in the reaction system
2, cause in this reaction system nitrogen oxides various informative, and be in the unsettled change procedure always, comprise NO, NO
2, N
2O
3, N
3O
4, the effective oxide of wherein participating in reaction generation methyl nitrite is N
2O
3, remaining oxide compound is generating N
2O
3The time also can generate the side reaction of materials such as nitric acid.In esterification reaction tower, realize the oxidizing reaction of NO before this, generated MN with methyl alcohol generation esterification then.For improving the selectivity of main reaction methyl nitrite; Suppress the generation of side reaction nitric acid; Usually one of measure of taking mainly is through allocating the charge proportion that suitable oxygen and carbonyl synthesis reactor export the NO that circulates, impelling the nitrogen oxides court in the esterification reaction tower system to help generating N
2O
3Direction carry out.Like NO and the O that describes among the patent CN 101190884A
2Proportional range be 0.01～0.1: 1, just improved N from essence
2O
3Generation, and then increased the selectivity of MN.Patent CN101096340A carries out oxidizing reaction and the esterification that generates methyl nitrite respectively in order to improve the selectivity of MN in two reactor drums, a part generates NO
2Oxidizing reaction in pre-reactor, carry out, realizes getting into again behind the NO partial oxidation reaction and accomplish the esterification regeneration that generates MN in the esterification reaction tower, and the mode through reactive distillation realizes separating of MN and nitric acid and water.
Reaction fractionating tower generally selects for use tray column or packing tower all can realize, as adopting sieve-tray tower, valve tray column in some instance, and the application of packing tower also is a kind of comparatively widely mode.
Because the nitrogen oxides conversion reaction is that a volumes is dwindled reaction process, and all reactions are strong exothermal reaction in the esterification system, helps reaction from thermodynamics angle analysis reduction temperature pressure boost and carry out.
A large amount of reaction heat that existing technology is produced the esterification regenerative response generally take two kinds of solutions to remove:
A solution is interchanger to be set remove reaction heat through recirculated cooling water on column plate; This mode can realize preferably that temperature distribution keeps consistent relatively on all column plates of entire reaction rectifying tower, and suitable reaction temperature improves MN esterification selectivity on the column plate through regulating.Yet the weak point of this technology is that the corresponding design and manufacture cost of reaction fractionating tower can significantly increase, and the heat-exchange equipment that on column plate, increases simultaneously can increase the resistance of full cycle reactive system, and then causes consumption of compressor significantly to rise.
Another kind of solution is that one group or a plurality of external heat exchanger are set outside reaction fractionating tower, returns higher level's column plate after the reaction solution on the column plate is cooled off through external heat exchanger through pump and gets into reaction zone again, and doing the benefit of bringing like this is that the device fabrication cost reduces.Obviously, the back-mixing of reaction solution can reduce the efficient of reactive distillation greatly, is unfavorable for the carrying out of regenerative response.
Existing methyl nitrite production technology generally is that the mode through reactive distillation realizes, this is connected on the reaction fractionating tower operation in the same circulation loop for one with the oxonation device, can bring bigger difficulty.Because a large amount of recycle gas passes through rectifying tower; Especially when the load of production plant is in the adjustment state; Be in normal work operating mode needs and constantly adjust vapour/liquor ratio for satisfying rectifying tower, this adjustment tends to bring the potential work accident as " dry plate " or " flooding " etc. takes place.
The tangible weak point that also has of this type technology is; A large amount of recycle gas are when leaving reaction fractionating tower; Even the mist tripping device has been installed at cat head; Still can carry other objectionable impuritiess that produce in the water of state of saturation, micro-nitric acid and some reaction process secretly, it is fatal to synthetic catalyst that these materials get into carbonyl synthesis reactor.Implement complete purifying treatment, come subcooling circulation gas through refrigerating apparatus is set usually, not only significantly increase plant investment and process cost, also can cause direct influence the change of carbongl group synthesis reaction processing condition.
Therefore; Need to produce a kind of continuous circulating esterification and oxo process dimethyl oxalate technology; That this technology not only will realize under any operating mode is stable, the purpose of oxidation efficiently and esterification generation MN; But also water, micro-nitric acid and other objectionable impuritiess that will guarantee to get in the recycle gas of oxonation device be eliminated basically, to realize NO and the maximum use of CO and the long-period stable operation of catalyzer.
Summary of the invention
The object of the present invention is to provide the industrial method of a kind of continuous circulating esterification and oxo process dimethyl oxalate technology; With alap factory construction cost and running cost; Realize stable operation and oxidation and esterification highly selective; And objectionable impurities in the recycle gas that gets into carbonyl synthesis reactor is reached to be satisfied its reaction requirement, the prolongation oxo catalyst working time of maximum possible.
For achieving the above object, the present invention adopts following technical scheme:
A kind of continuous circulating esterification and carbonylation coupling join the industrial method of producing dimethyl oxalate, comprise the steps:
1) esterification: make methyl alcohol, O
2With nitrogen oxides and flow into the reaction zone of esterification reaction tower, and react the generation methyl nitrite; The liquid stream that the reaction back produces flows out and circulates from the esterification reaction tower outlet at bottom and returns the reaction zone of esterification reaction tower; The gas stream that the reaction back produces flows out from the esterification reaction tower lower part outlet, and successively through purifying the mixed gas that obtains to contain the reaction product methyl nitrite with dry back; Said esterification reaction tower is a packing tower;
2) CO carbongl group synthesis reaction: make the methyl nitrite that obtains in CO and the step 1) that the carbonylation linked reaction take place in carbonyl synthesis reactor and generate dimethyl oxalate, and the NO that regenerates; NO returns the esterification reaction tower in the step 1).
In the step 1), the liquid stream that goes out from the esterification tower bottom flow is mainly unreacted methanol, contains the esterification reaction product methyl nitrite in the gas stream.
Said nitrogen oxides is NO, NO
2, N
2O
3And N
3O
4In one or more arbitrary combination.
Preferable, the charging of esterification reaction tower is selected from one of following manner:
Methyl alcohol, O
2With nitrogen oxides from esterification cat head sparger and flow into reaction zone;
O
2From charging between the packing section on esterification reaction tower top, and with the methyl alcohol and the nitrogen oxides that get into by tower distributor and flow into reaction zone.
Further, the liquid stream that comes out at the bottom of the esterification reaction tower outside tower after the water cooler cooling recycling return the reaction zone of esterification reaction tower., that esterification produced a large amount of generations heat are very convenient and be easy to remove through liquid stream in esterification reaction tower external circulation and heat exchange.
Preferable, the temperature of said esterification is 20 ℃～95 ℃, is preferably 30 ℃～90 ℃.The selectivity of NO oxidation and MN regenerated selectivity all are that optimum, too high or too low temperature all disadvantageous chemical reaction can take place to the oxidation of NO or the regeneration of MN in this TR, and final result shows that the magnitude of recruitment of NO has increased in the system.
In addition; Control to esterification reaction pressure also is very crucial; Because esterification reaction pressure not only influences the oxidation of NO and the regenerative response of MN, but also can have influence on the process that oxonation generates dimethyl oxalate, the economical operation and the construction investment of installing also had very big influence.Preferable, said esterification reaction pressure is 0.005-1.0MPa (G), that more excellent is 0.1-0.7MPa (G).
In above-mentioned continuous processing operational process provided by the present invention, needing successively the volume ratio of supply CO and oxygen is 8～2: 1 (v/v), and the NO of esterification reaction tower import and the volume ratio of oxygen are 3～12: 1 (v/v); The methyl alcohol of esterification reaction tower import and the mol ratio of oxygen are 15～5: 1.The formation of CO raw material can use gasification known in the art or other methods like the hydrocarbon conversion to form, and oxygen adopts the way of low temperature separation process to realize that NH is passed through in the source of NO usually
3The relevant nitrogenous inorganic salt of oxidizing process or utilization transform and obtain.
Generally, for the oxidation of satisfying NO and the regenerative response of MN normally carry out, recycle gas was controlled at 1～200 second in the residence time of esterification reaction tower, the minimizing of the residence time with prolong all to reacting unfavorable.
The exit gas logistics of esterification reaction tower is mainly the product nitrous acid ester, directly gets into scavenging tower bottom inlet, with the scavenging agent counter current contact from the purification cat head, purifies the gas stream of esterification outlet through scavenging agent.The preferred scavenging agent of the present invention is a water.The service temperature of scavenging tower can be at 10 ℃～60 ℃, preferred 25～60 ℃.Certainly, should adopt lower service temperature as far as possible for improving decontamination effect improving.Said scavenging tower is tray column or packing tower.
For the methyl nitrite gas dew point that makes the scavenging tower outlet reaches the requirement of satisfying oxonation, the present invention is provided with one group of moisture eliminator in operational path, adopts parallel connection or series system to connect between each moisture eliminator.The siccative that uses in the moisture eliminator is generally selected aluminum oxide or molecular sieve for use.In factory's operational process, moisture eliminator is on-line operation always, and through switching and regeneration, guarantees that another moisture eliminator is in stand-by state at any time.The dew-point temperature of dried gas material can be controlled in-60 ℃ to-5 ℃.
The reaction mass methyl nitrite that is come out by moisture eliminator gets into and with CO the carbonylation linked reaction takes place in the carbonyl synthesis reactor and generate dimethyl oxalate, and the NO that regenerates.Preferable, the inlet temperature of reaction of control carbonyl synthesis reactor is 80 ℃～165 ℃.Load Pd/Al in the carbonyl synthesis reactor
2O
3Catalyzer, temperature of reaction are controlled at 110 ℃～195 ℃, and reaction pressure is controlled at 0.1～1.0MPa.
The carbonylation linked reaction generates product dimethyl oxalate and a spot of by product; The outlet logistics of carbonyl synthesis reactor is isolated the thick product of dimethyl oxalate after thick reactor product cooler cooling; Noncondensable gas gets into the methanol wash tower and after methanol wash, isolates NO, and the esterification reaction tower inlet is returned in circulation.
Further, be mainly methyl alcohol through the isolated liquid stream of methanol wash tower, and contain a small amount of dimethyl oxalate, this liquid stream gets into the dimethyl oxalate knockout tower, isolates methyl alcohol and dimethyl oxalate.
According to preferable methods of the present invention; The heat that the carbonyl synthesis reactor reaction is produced can reclaim through the mode of byproduct steam; The common pressure range of the steam that is produced is at 0.4-1.3MPa (G), and this strand LP steam can be used for heating, product thermal treatment, rectifying and boiler supply water deaerating, the barkite pipeline of dimethyl oxalate and accompanies heat etc.
The main difference part of the present invention and prior art is that in fact the esterification reaction tower that the present invention adopted is equivalent to a plug flow reactor, and these are different fully with reactive distillation used in the prior art.The present invention carries out the regeneration esterification of methyl nitrite (MN) in packing tower, the esterification solution an of the best is provided in fact.The contriver thinks, realizes optimum MN regenerative process, and suitable process operation parameter, technical process and equipments choice have same importance.In the present invention, esterification reaction tower is not a reactor drum with refinery distillation, and is a plug flow reactor completely, and all reactant flow are from the reaction tower top or top and flow into reaction tower reaction, fresh methyl alcohol, fresh O
2And the NO that returns from carbonyl synthesis reactor outlet circulation and flow into esterification reaction tower, in esterification reaction tower, realize the oxidation of NO and the regenerative response of MN.Esterification reaction tower among the present invention is selected packing tower for use, and the main effect of filler is to increase gas/liquid interface contact area, has also played gas mixing and the dispersive effect of helping simultaneously.
Obviously; Esterification reaction tower outlet or bottom piece column plate liquid stream major part are looped back top of tower get into reaction zone again; Because this liquid phase stream major part is a unreacted methanol solution; This flow process is equivalent to increase the liquid dispersion process, has broken traditional rectifying theory, has also played crucial effects in the present invention.A large amount of unreacted methanol solution circulated, owing to significantly increased the filler liquid holdup, excessive methanol has played promoter action for esterification on the one hand; On the other hand; A large amount of round-robin methyl alcohol also help the absorption of esterification generation heat and take out of; Played keying action for control reaction temperature, and through esterification reaction tower extracorporeal circulation and heat exchange, a large amount of generation heat that esterification produced can be very convenient and be easy to remove.
Further in particular, the methanol loop system that esterification reaction tower of the present invention provides is very favorable for the stabilizing esterification reaction temperature with providing excessive methyl alcohol to carry out esterification.
The more important thing is; Adopt process method of the present invention, the operator of factory can carry out the esterification operation easily in actual moving process; Especially when the load of production plant is in the adjustment state; Even the recycle gas flow is big in this technological process, also needn't be as operating rectifying tower be in normal work operating mode and constantly adjust vapour/liquor ratio for satisfying rectifying tower, thoroughly avoided the potential work accident as " dry plate " or " flooding " etc. takes place.
Adopt process method of the present invention to also have a tangible benefit to be; Purification, drying through scavenging tower and moisture eliminator; Basically eliminated esterification reaction tower and ejected other objectionable impuritiess that produce in water, micro-nitric acid and some reaction process that gas carries secretly, and these materials to get into carbonyl synthesis reactors be fatal to synthetic catalyst.Thereby can be so that the carbongl group synthesis reaction catalyzer can long-period stable operation.
The present invention also further discloses a kind of above-mentioned continuous circulating esterification and carbonylation coupling realized and has joined the device of the industrial method of producing dimethyl oxalate, comprising: esterification reaction tower, methanol loop pump, scavenging tower, moisture eliminator, carbonyl synthesis reactor, thick reactor product cooler and methanol wash tower; Wherein: the bottom liquid logistics outlet of esterification reaction tower is connected through pipeline with the top inlet of esterification reaction tower through the methanol loop pump, and the lower gas logistics outlet of esterification reaction tower is connected through pipeline with the bottom inlet of scavenging tower; The tower top outlet of scavenging tower is connected through pipeline with the inlet of moisture eliminator; The outlet of moisture eliminator is connected through pipeline with the inlet of carbonyl synthesis reactor; The outlet of carbonyl synthesis reactor is connected through pipeline with the inlet of thick reactor product cooler; The outlet of thick reactor product cooler is connected through pipeline with the bottom of methanol wash tower inlet; The top exit of methanol wash tower is connected through pipeline with the top of esterification reaction tower inlet; Said esterification reaction tower is a packing tower.
Further, the top exit of methanol wash tower is connected through pipeline with the top inlet of esterification reaction tower through recycle compressor.
Further, said apparatus also comprises the methyl alcohol water cooler between the top inlet of being located at methanol loop pump and esterification reaction tower.Be used to cool off the external recycle stream of esterification reaction tower, thus esterification produced a large amount of generations heat are very convenient and be easy to remove.
Further, said apparatus also comprises the dimethyl oxalate knockout tower, and the inlet of dimethyl oxalate knockout tower is connected through pipeline with the outlet at bottom of methanol wash tower.Be used for separating from the effusive methanol solution that contains a small amount of dimethyl oxalate of methanol wash tower.
The present invention also further provides a kind of industrial method of producing dimethyl oxalate, comprises the steps: to make methyl alcohol, O
2With nitrogen oxides and flow into the reaction zone of esterification reaction tower, and react the generation methyl nitrite; The liquid stream that the reaction back produces flows out and circulates from the esterification reaction tower outlet at bottom and returns the reaction zone of esterification reaction tower; The gas stream that the reaction back produces flows out from the esterification reaction tower lower part outlet, and obtains methyl nitrite through purifying with dry back successively; Said esterification reaction tower is a packing tower.
The liquid stream that goes out from the esterification tower bottom flow is mainly unreacted methanol, and gas stream is mainly the product methyl nitrite.
Said nitrogen oxides is NO, NO
2, N
2O
3And N
3O
4In one or more arbitrary combination.
Preferable, the charging of esterification reaction tower is selected from one of following manner:
Methyl alcohol, O
2With nitrogen oxides from esterification cat head sparger and flow into reaction zone;
O
2From charging between the packing section on esterification reaction tower top, and with the methyl alcohol and the nitrogen oxides that get into by tower distributor and flow into reaction zone.
Further, the liquid stream that comes out at the bottom of the esterification reaction tower outside tower after the water cooler cooling recycling return the reaction zone of answering esterification reaction tower., that esterification produced a large amount of generations heat are very convenient and be easy to remove through liquid stream in esterification reaction tower external circulation and heat exchange.
Preferable, the temperature of said esterification is 20 ℃～95 ℃, is preferably 30 ℃～90 ℃.The selectivity of NO oxidation and MN regenerated selectivity all are that optimum, too high or too low temperature all disadvantageous chemical reaction can take place to the oxidation of NO or the regeneration of MN in this TR, and final result shows that the magnitude of recruitment of NO has increased in the system.
In addition; Control to esterification reaction pressure also is very crucial; Because esterification reaction pressure not only influences the oxidation of NO and the regenerative response of MN, but also can have influence on the process that oxonation generates dimethyl oxalate, the economical operation and the construction investment of installing also had very big influence.Preferable, said esterification reaction pressure is 0.005-1.0MPa (G), that more excellent is 0.1-0.7MPa (G).
In above-mentioned continuous processing operational process provided by the present invention, needing successively the volume ratio of supply CO and oxygen is 8～2: 1 (v/v), and the NO of esterification reaction tower import and the volume ratio of oxygen are 3～12: 1 (v/v); The methyl alcohol of esterification reaction tower import and the mol ratio of oxygen are 15～5: 1.The formation of CO raw material can use gasification known in the art or other methods like the hydrocarbon conversion to form, and oxygen adopts the way of low temperature separation process to realize that NH is passed through in the source of NO usually
3The relevant nitrogenous inorganic salt of oxidizing process or utilization transform and obtain.
Generally, for the oxidation of satisfying NO and the regenerative response of MN normally carry out, recycle gas was controlled at 1～200 second in the residence time of esterification reaction tower, the minimizing of the residence time with prolong all to reacting unfavorable.
The exit gas logistics of esterification reaction tower is mainly the product nitrous acid ester, directly gets into scavenging tower bottom inlet, with the scavenging agent counter current contact from the purification cat head, purifies the gas stream of esterification outlet through scavenging agent.The preferred scavenging agent of the present invention is a water.The service temperature of scavenging tower can be at 10 ℃～60 ℃, preferred 25～60 ℃.Certainly, should adopt lower service temperature as far as possible for improving decontamination effect improving.Said scavenging tower is tray column or packing tower.
For the methyl nitrite gas dew point that makes the scavenging tower outlet reaches the requirement of satisfying oxonation, the present invention is provided with one group of moisture eliminator in operational path, adopts the parallel connection or the mode that is connected in series between each moisture eliminator.The siccative that uses in the moisture eliminator is generally selected aluminum oxide or molecular sieve for use.In factory's operational process, moisture eliminator is on-line operation always, and through switching and regeneration, guarantees that another moisture eliminator is in stand-by state at any time.The dew-point temperature of dried gas material can be controlled in-60 ℃ to-5 ℃.
Aforesaid method provided by the present invention; Can not only realize that plant investment minimizes the purpose that generates methyl nitrite with the highly selective of implement device stable operation and oxidation and esterification; And water, micro-nitric acid and other objectionable impuritiess that can also guarantee to get in the recycle gas of oxonation device be eliminated basically, guarantees to realize the maximum use of NO and CO and the long-period stable operation of carbongl group synthesis reaction catalyzer.
Description of drawings
Fig. 1 is a process flow sheet of the present invention.
Embodiment
As shown in Figure 1, be used to realize that the device of process method of the present invention comprises at least: the external methyl alcohol water cooler of esterification reaction tower 1, methanol loop pump 2, esterification reaction tower 9, scavenging tower 3, moisture eliminator 4, carbonyl synthesis reactor 5, thick reactor product cooler 6, methanol wash tower 7, recycle compressor 10 and DMO (dimethyl oxalate) knockout tower 8.Should understand; In the practical implementation process; Off-set facility such as other equipment such as the Raw material pail that possibly use, vacuum meter, variable valve, temperature measuring set, pressure transmitter, storage tank are all implemented all fours with conventional chemical engineering, and these are not emphasis of the present invention place.In addition, various device mentioned among the present invention all can increase and decrease the table of equipment number on demand, perhaps also can increase such as facilities such as thick product separation jar, preheaters.
As shown in Figure 1, liquid methanol is by pipeline 12, O
2By pipeline 11 and the circulation gas NO that returns from carbonyl synthesis reactor 5 circulations together and flow into esterification reaction tower 1, liquid methanol and gas stream are distributed on the cat head filler of esterification reaction tower 1 by the sparger that is arranged on cat head.Liquid exit is delivered to methanol loop pump 2 through pipeline at the bottom of the tower, delivers to external methyl alcohol water cooler 9 by recycle pump 2 through pipeline again, and the top that cooled methanol solution returns esterification reaction tower 1 gets into the reaction zone reaction again.Therefore, the circular flow through control methyl alcohol just can be good at controlling TR required in the esterification reaction tower.Equally, the ratio that can be good at regulating NO and oxygen, CO and oxygen of the size through flow director control inlet stream.
Through liquid level at the bottom of the tower of the suitable esterification reaction tower 1 of fluid level controller control; Reacted gaseous stream leaves esterification reaction tower 1 and directly gets into the bottom or the bottom inlet of scavenging tower 3 in the esterification reaction tower 1; Component in this gaseous phase materials mainly is the nitric acid of the MN of esterification generation, unreacted CO, NO, methyl alcohol, water and by-product trace etc.; After in scavenging tower and from the abundant counter current contact of the detergent water of pipeline 13, absorbing, gaseous stream leaves scavenging tower 3 by scavenging tower 3 tops.Scavenging agent part by the tower bottom outlet 14 of scavenging tower 3 comes out can be returned scavenging tower 3 tops, less part removal system.
From the direct inlet that feeds a moisture eliminator 4 of gaseous stream that scavenging tower 3 comes out, control dried recycle gas dew point in-40 ℃ to-5 ℃ scopes.Dried gas mixes after preheater is heated to oxonation device 5 temperature ins with the fresh CO that replenishes through pipeline 15, gets in the oxonation device 5, and at Pd/Al
2O
3Carry out the carbonylation building-up reactions under the situation that catalyzer exists, generate dimethyl oxalate, and regeneration NO.The temperature of oxonation device 5 is controlled through the pressure of regulating drum provided thereon, controls the oxonation temperature usually between 110 ℃ to 195 ℃.
The outlet of oxonation device 5 is connected with the inlet of thick reactor product cooler 6, and this water cooler generally adopts temperature adjustment water that the dimethyl oxalate that oxonation generates is cooled to dew-point temperature, and the liquid phase dimethyl oxalate is isolated the thick product of dimethyl oxalate through separating tank.By a large amount of circulation gas that contain dimethyl oxalate that come out in the thick reactor product cooler 6; Send into methanol wash tower 7 through pipe connection; In this tower with circulation gas in remaining dimethyl oxalate slough fully, gas NO is come out to return esterification reaction tower 1 through recycle compressor 10 by the top of methanol wash tower 7.The methyl alcohol that methanol wash tower 7 used methyl alcohol can use DMO knockout tower 8 to reclaim.In factory's implementation process; On the pipeline of the top exit of connection methanol wash tower 7 and the top inlet of esterification reaction tower 1 pressure regulating device is set usually; Through the pressure that guarantees oxonation and whole circulation system of dominant discharge discharge unit inertia off-gas, satisfy carbonylation and esterification reaction pressure demand.
The liquid that methanol wash tower 7 outlet at bottoms come out is the methanol solution that contains dimethyl oxalate, is sent to DMO knockout tower 8 through pipeline and carries out methyl alcohol and DMO product separation, and the methyl alcohol that separates the back generation is flowed out by cat head pipeline 17, and DMO is flowed out by tower bottom tube road 18.This tower can be operated under normal pressure, and tower still temperature is controlled between 65-85 ℃.
Above-mentioned technological process provided by the present invention is explained with equipment such as a carbonyl synthesis reactor, esterification reaction tower, but is appreciated that under suitable situation the number of some or all these equipment all can increase.
Below in conjunction with embodiment the present invention is explained further details.
Adopt aforesaid process method to produce dimethyl oxalate.
(1) raw material liq methyl alcohol 2000kg/h is pressurized to the top sparger that 0.7MPa (G) is sent to esterification reaction tower 1,200Nm through pump
3/ h 0.5～1MPa (G) oxygen is sent to the top sparger of esterification reaction tower 1 through pipeline 11, mixes with circulation gas that recycle compressor 10 force feeds are come and flows into the reaction of filler reaction zone.The oxidation of NO and esterification all occur in the whole reactor space.Through opening the methanol loop pump 2 of esterification reaction tower 1 outlet at bottom, return the redistribution of esterification reaction tower 1 top after the 20t/h methanol solution is delivered to external methyl alcohol water cooler 9 coolings.85 ℃ of esterification controlled temperature, the selectivity that reaction pressure 0.65MPa (G), NO are converted into MN can reach 96%.
(2) esterification reaction tower 1 outlet reactant gases (circulation gas) total amount is 22000Nm
3/ h; Gaseous fraction mainly is the nitric acid of the MN of esterification generation, unreacted CO, NO, methyl alcohol, water and by-product trace etc.; Be sent to scavenging tower 3 bottoms through pipeline, with scavenging agent water counter current contact, the recycle gas after the purification leaves from cat head and gets into moisture eliminator 4.The tower bottom outlet scavenging agent part of scavenging tower 3 can be returned scavenging tower 3 tops, less part removal system.The working pressure 0.55MPa (G) of scavenging tower 3,25 ℃ of service temperatures.
(3) recycle gas that leaves scavenging tower 3 gets into moisture eliminator 4, is filled with activated alumina ball or molecular sieve in the moisture eliminator 4, and behind adsorbents adsorb moisture, the circulation gas dew point is controlled at-40 ℃.In moisture eliminator comes into operation process, through the dew-point temperature variation tendency of analysis cycle gas, in time switch moisture eliminator, and through regenerating to guarantee that moisture eliminator is in online stand-by state.
(4) the fresh CO raw material gas flow that replenishes is 1000Nm
3/ h mixes with the recycle gas that leaves moisture eliminator 4, through preheater heat exchange to 90 ℃ entering carbonyl synthesis reactor 5, at Pd/Al
2O
3Carry out building-up reactions under the situation that catalyzer exists.Temperature of reaction is controlled at 170 ℃ through regulating drum pressure; Reaction pressure is controlled at 0.55MPa (G); Reaction product is dimethyl oxalate, methylcarbonate, dme, methyl-formiate etc.; All the other trace and even trace, wherein the selectivity of dimethyl oxalate is 99%, the transformation efficiency 80% of methyl nitrite.The exit gas component also has unreacted CO, the NO of methyl nitrite, reaction regeneration and rare gas element N
2
(5) after carbonyl synthesis reactor 5 exit gass leave reactor drum; To react the dimethyl oxalate that generates through thick reactor product cooler 6 and be cooled to dew-point temperature; Separate as thick product after most of dimethyl oxalate cooling; Uncooled dimethyl oxalate is sent to recycle compressor 10 inlets in the recycle gas after 7 washings of methanol wash tower.At compressor 10 inlets one regulating valve is set and puts the pressure-stabilisation that the small portion rare gas element is guaranteed whole reaction system through speeding.Recycle gas after methyl alcohol is washed to 0.68MPa (G), gets into esterification reaction tower 1 top inlet through pipeline through recycle compressor 10 compression pressure-raisings.
(6) methanol solution that contains dimethyl oxalate that washs mixes with the dimethyl oxalate that separates and together to be sent to DMO knockout tower 8, and this tower is kept micro-pressure operation, and 160 ℃ of tower still service temperatures, tower top temperature are 70 ℃.
Producing dimethyl oxalate according to this process method is 2500kg/h, dimethyl oxalate purity 99.5%, CO unit consumption≤500Nm
3/ t.DMO.
Embodiment 2
The esterification reaction tower exit gas is after super-dry, and dew point control is left moisture eliminator for-20 ℃, with the fresh CO gas flow that replenishes be 2900Nm
3/ h mixes process carbonyl synthesis reactor 5 inlet preheaters and is preheating to 150 ℃ of entering reactor drums, at Pd/Al
2O
3Carry out building-up reactions under the situation that catalyzer exists.Temperature of reaction is controlled at 190 ℃ through regulating drum pressure; Reaction pressure is controlled at 0.75MPa (G); Reaction product is dimethyl oxalate, methylcarbonate, dme, methyl-formiate etc.; All the other trace and even trace, wherein the selectivity of dimethyl oxalate is 99.5%, the transformation efficiency 90% of methyl nitrite.The exit gas component also has unreacted CO, the NO of methyl nitrite, reaction regeneration and rare gas element N2.
Producing dimethyl oxalate according to this process method is 7500kg/h, dimethyl oxalate purity 99.5%, CO unit consumption≤480Nm
3/ t.DMO.
Claims (19)
1. continuous circulating esterification and carbonylation coupling join the industrial method of producing dimethyl oxalate, comprise the steps:
1) esterification: make methyl alcohol, O
2With nitrogen oxides and flow into the reaction zone of esterification reaction tower, and react the generation methyl nitrite; The liquid stream that the reaction back produces flows out and circulates from the esterification reaction tower outlet at bottom and returns the reaction zone of esterification reaction tower; The gas stream that the reaction back produces flows out from the esterification reaction tower lower part outlet, and successively through purifying the mixed gas that obtains to contain the reaction product methyl nitrite with dry back; Said esterification reaction tower is a packing tower;
2) CO carbongl group synthesis reaction: make the methyl nitrite that obtains in CO and the step 1) that the carbonylation linked reaction take place in carbonyl synthesis reactor and generate dimethyl oxalate, and the NO that regenerates; NO returns the esterification reaction tower in the step 1).
2. continuous circulating esterification as claimed in claim 1 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that said nitrogen oxides is NO, NO
2, N
2O
3And N
3O
4In one or more arbitrary combination.
3. continuous circulating esterification as claimed in claim 1 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that the charging of esterification reaction tower is selected from one of following manner:
Methyl alcohol, O
2With nitrogen oxides from esterification cat head sparger and flow into reaction zone;
O
2From charging between the packing section on esterification reaction tower top, and with the methyl alcohol and the nitrogen oxides that get into by tower distributor and flow into reaction zone.
4. continuous circulating esterification as claimed in claim 1 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that, the liquid stream that comes out at the bottom of the esterification reaction tower tower outside after water cooler cools off recycling return the reaction zone of esterification reaction tower.
5. continuous circulating esterification as claimed in claim 1 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that the temperature of said esterification is 20 ℃～95 ℃; Said esterification reaction pressure is 0.005-1.0MPa.
6. join the industrial method of producing dimethyl oxalate like arbitrary described continuous circulating esterification and carbonylation coupling among the claim 1-5; It is characterized in that; The exit gas logistics of esterification reaction tower directly gets into scavenging tower bottom inlet; With scavenging agent counter current contact, purify the gas stream of esterification reaction tower outlet through scavenging agent from the purification cat head.
7. continuous circulating esterification as claimed in claim 6 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that said scavenging agent is a water; Said scavenging tower is tray column or packing tower, and the service temperature of scavenging tower is 10 ℃～60 ℃.
8. join the industrial method of producing dimethyl oxalate like arbitrary described continuous circulating esterification and carbonylation coupling in claim 1-5 or 7, it is characterized in that, the said dry siccative that uses is selected aluminum oxide or molecular sieve for use; The dew-point temperature of dried gas material is controlled at-60 ℃ to-5 ℃.
9. continuous circulating esterification as claimed in claim 8 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that, said dry one group of moisture eliminator that adopts adopts parallel connection or series system to connect between each moisture eliminator.
10. join the industrial method of producing dimethyl oxalate like arbitrary described continuous circulating esterification and carbonylation coupling among the claim 1-5,7 or 9; It is characterized in that said carbonyl synthesis reactor is the reactor drum of single reactor drum or a plurality of employing parallel connection or series system connection.
11. continuous circulating esterification as claimed in claim 10 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that, the temperature in of control carbonyl synthesis reactor is 80 ℃～165 ℃; Load Pd/Al in the carbonyl synthesis reactor
2O
3Catalyzer, temperature of reaction are controlled at 110 ℃～195 ℃, and reaction pressure is controlled at 0.1～1.0MPa.
12. join the industrial method of producing dimethyl oxalate like arbitrary described continuous circulating esterification and carbonylation coupling among the claim 1-5,7,9 or 11; It is characterized in that the outlet logistics of carbonyl synthesis reactor is isolated the thick product of dimethyl oxalate after thick reactor product cooler cooling; Noncondensable gas gets into the methanol wash tower and after methanol wash, isolates NO, and esterification reaction tower is returned in circulation.
13. continuous circulating esterification as claimed in claim 12 and carbonylation coupling join the industrial method of producing dimethyl oxalate, it is characterized in that, get into the dimethyl oxalate knockout tower through the isolated liquid stream of methanol wash tower, isolate methyl alcohol and dimethyl oxalate.
14. an industrial method of producing methyl nitrite comprises the steps: to make methyl alcohol, O
2With nitrogen oxides and flow into the reaction zone of esterification reaction tower, and react the generation methyl nitrite; The liquid stream that the reaction back produces flows out and circulates from the esterification reaction tower outlet at bottom and returns the reaction zone of esterification reaction tower; The gas stream that the reaction back produces flows out from the esterification reaction tower lower part outlet, and obtains methyl nitrite through purifying with dry back successively; Said esterification reaction tower is a packing tower.
15. the industrial method of production methyl nitrite as claimed in claim 14 is characterized in that, said nitrogen oxides is NO, NO
2, N
2O
3And N
3O
4In one or more arbitrary combination.
16. the industrial method of production methyl nitrite as claimed in claim 14 is characterized in that, the liquid stream that comes out at the bottom of the esterification reaction tower outside tower after the water cooler cooling recycling return the reaction zone of esterification reaction tower.
17. the industrial method of production methyl nitrite as claimed in claim 14 is characterized in that, the temperature of said esterification is 20 ℃～95 ℃; Said esterification reaction pressure is 0.005-1.0MPa.
18. industrial method like arbitrary described production methyl nitrite among the claim 14-17; It is characterized in that; The exit gas logistics of esterification reaction tower directly gets into scavenging tower bottom inlet; With scavenging agent counter current contact, purify the gas stream of esterification outlet through scavenging agent from the purification cat head.
19. the industrial method of production methyl nitrite as claimed in claim 18 is characterized in that, the said dry siccative that uses is selected aluminum oxide or molecular sieve for use; The dew-point temperature of dried gas material is controlled at-60 ℃ to-5 ℃.
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| CN103483150A (en) * | 2013-08-31 | 2014-01-01 | 安徽淮化股份有限公司 | Method and device for producing and synthesizing ethylene glycol by using coal as raw material |
| CN109400480A (en) * | 2017-08-18 | 2019-03-01 | 上海浦景化工技术股份有限公司 | A kind of method and apparatus preparing methyl nitrite |
| CN109942371A (en) * | 2019-03-20 | 2019-06-28 | 江苏凯美普瑞工程技术有限公司 | Stacked coal-to-ethylene glycol reaction device and method |
| CN113956161A (en) * | 2021-11-22 | 2022-01-21 | 中国科学院宁波材料技术与工程研究所 | Method and system for continuously producing dimethyl carbonate |
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| CN101190884A (en) * | 2006-11-21 | 2008-06-04 | 上海焦化有限公司 | A kind of method of synthesizing dimethyl oxalate and by-product dimethyl carbonate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103483150A (en) * | 2013-08-31 | 2014-01-01 | 安徽淮化股份有限公司 | Method and device for producing and synthesizing ethylene glycol by using coal as raw material |
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| CN109400480A (en) * | 2017-08-18 | 2019-03-01 | 上海浦景化工技术股份有限公司 | A kind of method and apparatus preparing methyl nitrite |
| CN109400480B (en) * | 2017-08-18 | 2022-01-04 | 上海浦景化工技术股份有限公司 | Method and equipment for preparing methyl nitrite |
| CN109942371A (en) * | 2019-03-20 | 2019-06-28 | 江苏凯美普瑞工程技术有限公司 | Stacked coal-to-ethylene glycol reaction device and method |
| CN113956161A (en) * | 2021-11-22 | 2022-01-21 | 中国科学院宁波材料技术与工程研究所 | Method and system for continuously producing dimethyl carbonate |
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