CN101462961B - Process flow for producing ethylene glycol with coproduction product dimethyl carbonate - Google Patents
Process flow for producing ethylene glycol with coproduction product dimethyl carbonate Download PDFInfo
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Abstract
The invention provides a serial process for synthesizing glycol and co-producing methyl carbonate with CO as starting raw material. The major process is carried out under the condition of gas phase: firstly, CO and methyl nitrite are carried out gas-phase oxidation coupled reaction to synthesize dimethyl oxalate and methyl carbonate; subsequently, methyl carbonate is separated out by a distillingtower, and heavy component dimethyl oxalate is processed by catalytic hydrogenation to obtain glycol. Methyl nitrite consumed during the oxidation coupled reaction can be supplemented by a regeneration tower (NO, O2 and methanol synthesis methyl nitrite. The main raw materials consumed in the process are inexpensive CO, O2, H2, methyl alcohol and the like, while the products of the process are glycol and methyl carbonate with high added value. The process is applicable to industrial production.
Description
The present invention relates to utilize cheap CO, O
2, H
2Reach raw materials such as methyl alcohol, the processing method of Industrial products such as the ethylene glycol of production high added value and methylcarbonate.
Ethylene glycol (being called for short EG) is the starting material with multiple industrial use, and main application is for producing trevira, Synolac, frostproofer or solvent etc.
Methylcarbonate (being called for short DMC) is used widely at industrial circles such as agricultural chemicals, medicine, plastics, electronic chemical product, fodder additivess.
This technology is carried out oxidative coupling reaction earlier by CO, methyl nitrite in the presence of palladium catalyst, generate dimethyl oxalate and methylcarbonate, and after fractionation by distillation, dimethyl oxalate and hydrogen carry out gas-phase reaction and makes ethylene glycol in the presence of hydrogenation catalyst; Distillation tower ejects the methylcarbonate (forming azeotrope with methyl alcohol) that comes and remove methyl alcohol in the pressurization knockout tower, obtains methylcarbonate.The oxidative coupling reaction of this process must carry out under platinum group catalysis; The hydrogenation catalyst reaction of dimethyl oxalate must be carried out under copper, barium, the catalysis of molybdenum element.
The continuous process of preparation dimethyl oxalate provided by the invention, methylcarbonate and ethylene glycol has very big originality, can utilize CO, nitrous acid ester and hydrogen to produce ethylene glycol with coproduction product dimethyl carbonate in industrial application.
Main process prescription of the present invention is as follows:
The first step, CO oxidative coupling reaction synthesizing dimethyl oxalate and methylcarbonate: the gas raw material that contains CO and methyl nitrite enters into the fixed-bed reactor that are filled with the solid platinum catalyzer after metering, carries out gas phase catalytic reaction.Reactor can use the single tube or the shell-and-tube reactor of loading catalyst, and the residence time of vapor-phase reactant in catalytic bed is no more than 12 seconds at most, and the suitable residence time is 0.2～6 second.The used catalyzer of oxidative coupling reaction is a platinum group; The gas reaction raw material is before entering reactor, usually with rare gas element such as nitrogen or CO2 dilution in addition.This reaction can be carried out under relatively low temperature, and typical temperature is 50～200 ℃, and preferred temperature is 60～180 ℃, in addition for reaction pressure, can select 0～2MPa, and preferred pressure is 0～1.0Mpa.The concentration of methyl nitrite can have bigger variation range in the gas phase initial feed, but in order to obtain suitable speed of reaction, the concentration of methyl nitrite is minimum must not to be lower than 3% volumetric concentration, generally should be controlled at 5～30% volumetric concentrations.The concentration of CO also can have bigger variation range in the gas phase initial feed, generally should be controlled at 10～90% volumetric concentrations.
In second step, oxidative coupling reaction product condensation separation process: the reaction product that the first step process is come out enters in the condenser, after the product condensation is got off, non-condensable gas can be separated from phlegma.Main ingredient is dimethyl oxalate and methylcarbonate in the lime set that is condensed; On the other hand, mainly contain the gaseous fractions such as NO that unreacted CO, methyl nitrite and the first step reaction generate in the non-condensable gas.In addition, second walks out of dimethyl oxalate and the methylcarbonate that next part is taken out of by non-condensable gas, the water institute hydrolysis that is generated by (NO is regenerated as the reaction of methyl nitrite) in the 3rd step process, the oxalic acid that produces also may be rich long-pending in gas-circulating system, and dimethyl oxalate has higher relatively condensation point, may on condenser wall, crystallize out, and finally stop up condenser.In order to address these problems, the material that the second step process is come out need be controlled temperature well, and purpose product of the present invention is dimethyl oxalate and methylcarbonate, and the refrigerative temperature preferably is controlled between 60～80 ℃.
In the 3rd step, the methyl nitrite regenerative process: the non-condensable gas that the second step process is separated enters regenerator column, contacts with the gas of oxygenous and methyl alcohol, makes NO be converted into the regenerated methyl nitrite.Regenerator column in this step can use the good packing tower that contacts of gas-liquid, bubble-plate column, spray column etc. usually.The gas of non-condensable gas and oxygenous and methyl alcohol enters regenerator column.In regenerator column, a part of NO is oxidized to NO
2, meanwhile, these materials are absorbed and react with methyl alcohol, thereby obtain the regenerated methyl nitrite.In this step, should control the concentration of the NO that leaves regenerator column well, be preferably 1～10% volumetric concentration, and reduce NO as far as possible
2And the content of oxygen, preferably do not contain NO
2And oxygen.When above-mentioned gas loops back in the reactor in the first step, if the concentration of NO is higher than above-mentionedly than ceiling value in the resurgent gases, the speed of reaction that generates dimethyl oxalate will reduce, and yield also can descend.On the other hand, if the concentration of NO is lower than above-mentioned low limit value, the NO in circulation gas
2The content that reaches oxygen will rise, and this will reduce the solid palladium activity of such catalysts, and can increase the amount of by product.So when entering regenerator column, should be according to 0.05～0.3 mole of O of per 1 mole of NO correspondence
2Amount prepare, and the temperature of reaction of these gases when contacting with methyl alcohol should not be higher than the boiling point of methyl alcohol, reaction time is preferably 0.5～20 second; General used quantity of methyl alcohol is introduced regenerator column with NO by 1～10: 1 gas volume ratio.In addition, the loss of nitrogen can be passed through to add methyl nitrite to the first step reaction process, or adds nitrogen oxide such as NO, NO
2, N
2O
3, N
2O
4, or in the 3rd step process, replenished for regenerator column adds nitrous acid.In addition, if in the second step process, the too high levels of NO in the non-condensable gas, and also the amount of the methyl nitrite that obtains by regeneration in the 3rd step is too much, so just will all not import regenerator column by non-condensable gas, turn back in the reactor of the first step and the part non-condensable gas directly should be circulated.Leave the gas that contains methyl nitrite of regenerator column, be circulated back in the reactor of the first step.In addition, this resurgent gases also can with together enter in the reactor after CO mixes.The liquid that leaves regenerator column is to contain methanol in water, and water is the by product of regenerative response.This alcoholic solution can be purified to required input concentration with methanol solution by operations such as distillation, extractions, and with this pure liquid as the 3rd step process, or the required methanol feedstock of the second step process that under conditions suitable, also can be used as source.
The 4th step, dimethyl oxalate and methylcarbonate sepn process: the dimethyl oxalate that contains that comes out from the second step process enters distillation tower with the lime set of methylcarbonate and separates, what cat head came out is the azeotrope of methylcarbonate and methyl alcohol, and then enter the pressurization knockout tower separate, what pressurization separation Tata still came out is the methylcarbonate product, what cat head obtained is the thick methyl alcohol that contains the small amount of carbon dimethyl phthalate, but recirculation turned back in second step.What distillation Tata still came out is the material that contains dimethyl oxalate and small amount of methanol, enters hydrogenator after heating.
The 5th step, dimethyl oxalate shortening process: after the material that contains dimethyl oxalate that distillation Tata still comes out is heated, the ethyl glycolate of separating with hydrogen and follow-up ethylene glycol rectifying tower mixes, enter then in the packed-bed reactor that is filled with hydrogenation catalyst, carry out gas phase catalytic reaction.Reactor can use fixed bed or fluidized-bed reactor, and gas should not be preferably 0.2～2 second more than 5 seconds in the residence time of catalytic bed.Hydrogenation catalyst is the chromite of copper, molybdenum or barium, or the chromic salt of these metals.Temperature of reaction is generally 150～350 ℃, preferred 160～240 ℃; Reaction pressure is not less than normal pressure, preferred 1～4MPa.The primary product that this step process is come out is corresponding other by products that ethylene glycol and dimethyl oxalate hydrogenation are generated.Wherein contain the ethyl glycolate that a spot of dimethyl oxalate partial hydrogenation generates.The material that catalytic hydrogenation reaction Tata still comes out enters and is condensed into liquid in the condenser after the heat exchange cooling.The non-condensable gas of the hydrogen separated of being condensed returns in the hydrogenator as hydrogen source.
The 6th step: the rectification and purification of ethylene glycol: the lime set that contains ethylene glycol that the 5th step process is come out is introduced into pre-distillation column, and in this tower, ethylene glycol and methyl alcohol and unreacted dimethyl oxalate etc. are separated.The methanol solution that is distilled out can return the 3rd step process through circulation, one of originates as the alcohol of regenerator column.And can be used as one of source of the second step condensation process required alcohol.The ethylene glycol that fore-distillation Tata still comes out enters rectifying tower and further separates purification, and the light constituent that the rectifying tower cat head comes out mainly contains ethyl glycolate.And ethyl glycolate can obtain purpose product ethylene glycol by further hydrogenation, thus the ethyl glycolate fractionation by distillation come out the back the 5th step process that turns back to capable of circulation.Rectifying Tata still obtains is purpose product ethylene glycol.
Accompanying drawing 1 is a process flow diagram of the present invention, 1 is the oxidative coupling reaction device, and 7 is the catalytic hydrogenation reaction device, and 2 and 9 is condenser, 3 is the nitrous acid ester regenerator column, 4 is distillation tower, and 5 are the pressurization knockout tower, and 10 is the ethylene glycol pre-distillation column, 11 is the ethylene glycol rectifying tower, 6 is well heater, and 8 is interchanger, and 20～48 is pipeline.
From the unstripped gas that contains CO of pipeline 20, with the unstripped gas that contains methyl nitrite and NO etc. from pipeline 21, after the compression of gas recirculation device (not shown), enter in the reactor 1 that is filled with platinum metal catalysts by pipeline 22. What carry out in this reactor is gas-phase reaction, and gaseous reaction product enters condenser 2 through flowing out from the bottom behind the beds behind pipeline 23.
In condenser 2, gaseous product contacts with methyl alcohol from pipeline 25 in condensation, and the lime set that mainly contains dimethyl oxalate and dimethyl carbonate flows out from pipeline 30. On the other hand, contain the fixed gas of unreacted CO and methyl nitrite, and the accessory substance NO that generates in the reaction enters the regenerator bottom by pipeline 24.
In regenerator 3, fixed gas and the oxygen containing gas by pipeline 27 at the bottom of the tower, and carry out reverse contact by the logistics that contains methyl alcohol of pipeline 28 and reaction generates methyl nitrite from cat head, in this regenerator, NO is converted into NO after oxidation reaction2, namely generated methyl nitrite by the methanol liquid chemical absorbing subsequently, if it is inadequate to generate the required nitrogen of methyl nitrite reaction, can replenish NO by pipeline 26.
The gas that contains methyl nitrite that generates in regenerator 3 is by pipeline 21 and 22 recirculation Returning reactors 1, and fresh CO provides by pipeline 20. On the other hand, the water byproduct that generates in the regenerator 3 is passed through pipeline 29 at the bottom of tower, with the aqueous solution outflow of methyl alcohol. Alcohol liquid also can turn back to regenerator 3 or condenser 2 by pipeline 28 or 25 recirculation.
The condensate liquid that contains dimethyl oxalate and dimethyl carbonate that condenser 2 obtains flows out from pipeline 30, entering destilling tower 4 separates, what the cat head of destilling tower 4 came out is the azeotropic mixture of dimethyl carbonate and methyl alcohol, entering separation tower 5 separates again, what separation Tata still came out is the dimethyl carbonate product, cat head obtains containing the thick methyl alcohol of a small amount of dimethyl carbonate, turns back in the second step by pipeline 32 recirculation. The material that contains dimethyl oxalate that the tower reactor of destilling tower 4 is come out is with after the ethyl glycolate of coming from pipeline 47 mixes, compressed after the certain pressure value, enter heater 6 by pipeline 34, this contact with hydrogen from pipeline 35 mix after, flow out from pipeline 36, enter the hydrogenation reactor 7 that is filled with hydrogenation catalyst, gaseous reaction product flows out through pipeline 37, after heat exchanger 8 heat exchange cooling, enter condenser 9 through pipeline 38.
In condenser 9, gaseous reaction product is by further condensation, the lime set that mainly contains ethylene glycol enters pre-distillation column 10 by pipeline 41, on the other hand, the fixed gas of main hydrogen flows out from pipeline 39, and is compressed after the certain pressure value, enter heat exchanger 8 after the heat exchange heating, flow out from pipeline 40, after the hydrogen of pipeline 35 mixes, enter heater 6.
In pre-distillation column 10, methyl alcohol is distilled out of by pipeline 42, turns back in the regenerator 3 after recycling as methanol feedstock by pipeline 43,44 and 28 then. In addition, if the operation operating mode needs, a part of methyl alcohol can turn back in the condenser 2 by pipeline 45 and 25, and component heavier in the pre-distillation column enters rectifying column 11 by pipeline 46.
Heat up in a steamer in the tower 11 in rectifying, ethyl glycolate is removed as accessory substance is separated, the ethyl glycolate that is separated flows out by pipeline 47, enter the heater 6 by pipeline 34 after mixing with the dimethyl oxalate that comes out from the tower reactor of destilling tower 4, on the other hand, purpose product ethylene glycol divides by pipeline 48 outflows as restructuring.
Below describe in further detail in conjunction with specific embodiments again:
In the reactor 1 of stainless steel single tube (internal diameter 37mm, the pipe of height 1500mm), the gamma-alumina catalyzer (diameter is the little ball of 4mm) of filling 1.8kg supported palladium (weight ratio 0.6%).
(pressure 0.025MPa, volume consists of: 23.0% is CO, 8.1% methyl nitrite, 4.1%NO, 8.4% methyl alcohol, 9.5%CO to the gas mixture of the gas composition of being returned by CO and regenerator column
2And 46% nitrogen), be preheating to 90 ℃ with interchanger earlier, add from the beds top with 12000 liters flow velocity per hour with the gas diaphragm pump then, temperature of reaction is controlled at about 110 ℃, the temperature of beds by automatic temp controller guarantee temperature deviation be not more than ± 1 ℃.
After gas flows out from beds, from loading Packed condenser 2 (internal diameter 158mm, height 1400mm) bottom enters, methyl alcohol enters (per hour 5.8 liters) from condenser overhead, gas-liquid is carried out counter current contact (32 ℃ of condenser top temperature, about 42 ℃ of bottom temp) at this, and the condensate flow that comes out in condenser bottom is that (weight consisted of: 33.6% dimethyl oxalate in 2.9kg/ hour, 17.9% methylcarbonate, 0.02% formic acid methyl, 48.1% methyl alcohol), on the other hand, non-condensable gas ejects (per hour about 11800 liters from condenser, volume consists of: 15.5%CO, 3.8% nitrous acid methyl, 6.7%NO, 24.3% methyl alcohol, 7.7%CO
2, 41.3% nitrogen).
After non-condensable gas comes out, mix with oxygen (145 liters/hour), the mol ratio of mixing back oxygen and NO is 0.16, gas mixture is from regenerator column bottom (internal diameter 160mm, height 1450mm) enters, methyl alcohol (comprising the methyl alcohol that regenerator column reclaims) is from the regenerator column top, enter with 42 liters feed rate per hour that (this part methyl alcohol wherein is to return after pre-distillation column 10 separates, about 2.3 liters/hour) in the regenerator column, the gas-liquid counter current contact, temperature is about 35 ℃, 30 ℃ of regeneration overhead temperature, about 40 ℃ of bottom temp.NO is regenerated as methyl nitrite at this, the gas of regenerator column (15.5%CO, 8% methyl nitrite, 2.7%NO, 24.2% methyl alcohol, 7.6%CO
2, 41.3% nitrogen) come out with 11700 liters/hour speed after, remix CO gas (560 liters/hour of gas flows), gas mixture are cooled to 20 ℃ after being recycled the compression of gas force (forcing) pump, more condensed methyl alcohol are removed, and then it are imported reactor 1.
The lime set that condenser 2 comes out (2.9kg/h) enters distillation tower 4 (internal diameter 30mm, height 2000mm), about 65 ℃ of distillation tower top temperature, and column bottom temperature is 145 ℃.What the tower still came out is the thick liquid of dimethyl oxalate (1.5kg/h), the methylcarbonate that cat head comes out and the azeotrope of methyl alcohol (flow is 1.4kg/ hour), after being pressurized to 4MPa, enter pressurization knockout tower 5 (internal diameter 30mm, height 3000mm) in, about 155 ℃ of pressurizing tower tower top temperature, column bottom temperature is 205 ℃.What come out at the bottom of the tower is that purity is 98.6% methylcarbonate product (flow is 0.4kg/ hour).
After the lime set that contains ethyl glycolate (0.09kg/h) that thick liquid of dimethyl oxalate (1.5kg/h) and the rectifying tower 11 that the tower still of distillation tower 4 comes out comes out is mixed, again after being pressurized to 3MPa, with hydrogen (74% hydrogen that is heated to 200 ℃, 25.2% nitrogen, pressure 3Mpa, 19000 liters/hour of flows) mix after, join (internal diameter 43mm in the reactor 7 as raw material, height 1500mm loads 2 liters of solid hydrogenation catalysts).The gas that reactor 7 comes out enters condenser 9 (internal diameter 55mm, height 1500mm), is cooled to 40 ℃.The condensate flow that comes out in condenser bottom is that (weight consisted of: 22.8% ethylene glycol in 1.65kg/ hour, 75.4% methyl alcohol, 1.7% ethyl glycolate), on the other hand, eject next noncondensable gas (18600 liters/hour of flows from condenser, volume is formed: 71.8% hydrogen, 26.2% nitrogen) as the hydrogen feed recycling.The lime set that condenser 9 comes out (flow 1.65kg/ hour) imports in the pre-distillation column 10 (internal diameter 30mm, height 3000mm), about 65 ℃ of fore-distillation cat head temperature, and column bottom temperature is 158 ℃.The methyl alcohol that cat head steams is back to regenerator column utilization (1.2 liters/hour of flows) as the recirculation material.On the other hand, the heavy constituent that obtain at the bottom of the tower (flow is 1.01kg/ hour, and weight consists of 91.6% ethylene glycol, 7% ethyl glycolate) enter into rectifying tower 11 (internal diameter 30mm, height 3000mm), about 95 ℃ of cat head controlled temperature, and column bottom temperature is 158 ℃.The ethyl glycolate that cat head comes out (flow is 0.09kg/ hour), recirculation turns back in the reactor 7, and on the other hand, what come out at the bottom of the tower is that purity is 98.5% ethylene glycol product (flow is 0.92kg/ hour).
In the reactor 1 of stainless steel single tube (internal diameter 37mm, the pipe of height 1500mm), the gamma-alumina catalyzer (diameter is the little ball of 5mm) of filling 1.0kg supported palladium (weight ratio 0.6%).
(pressure 0.02MPa, volume consists of: 21.0% is CO, 9.6% methyl nitrite, 4.1%NO, 10.4% methyl alcohol, 6.0%CO to the gas mixture of the gas composition of being returned by CO and regenerator column
2And 48% nitrogen), be preheating to 90 ℃ with interchanger earlier, add from the beds top with 6000 liters flow velocity per hour with the gas diaphragm pump then, temperature of reaction is controlled at about 110 ℃, the temperature of beds by automatic temp controller guarantee temperature deviation be not more than ± 1 ℃.
After gas flows out from beds, from loading Packed condenser 1 (internal diameter 158mm, height 1400mm) bottom enters, methyl alcohol enters (per hour 2.9 liters) from condenser overhead, gas-liquid is carried out counter current contact (32 ℃ of condenser top temperature, about 42 ℃ of bottom temp) at this, and the condensate flow that comes out in condenser bottom is that (weight consisted of: 36.6% dimethyl oxalate in 1.5kg/ hour, 14.9% methylcarbonate, 0.02% formic acid methyl, 48.1% methyl alcohol), on the other hand, non-condensable gas ejects (per hour about 6800 liters from condenser, volume consists of: 15.4%CO, 3.9% methyl nitrite, 6.5%NO, 24.5% methyl alcohol, 7.7%CO
2, 41.4% nitrogen).
After non-condensable gas comes out, mix with oxygen (74 liters/hour), the mol ratio of mixing back oxygen and nitrogen is 0.14, gas mixture is from regenerator column bottom (internal diameter 160mm, height 1450mm) enters, methyl alcohol (comprising the methyl alcohol that regenerator column reclaims) is from the regenerator column top, enter with 22 liters feed rate per hour that (this part methyl alcohol wherein is to return after pre-distillation column 10 separates, about 1.2 liters/hour) in regenerator column, the gas-liquid counter current contact, temperature is about 35 ℃, 30 ℃ of regeneration overhead temperature, about 40 ℃ of bottom temp.NO is regenerated as methyl nitrite at this, the gas of regenerator column (15.5%CO, 8% methyl nitrite, 2.7%NO, 24.2% methyl alcohol, 7.6%CO
2, 41.3% nitrogen) come out with 6900 liters/hour speed after, remix CO gas (290 liters/hour of gas flows), gas mixture are cooled to 20 ℃ after being recycled the compression of gas force (forcing) pump, more condensed methyl alcohol are removed, and then it are imported reactor 1.
The lime set that condenser 2 comes out (1.6kg/h) enters distillation tower 4 (internal diameter 30mm, height 2000mm), about 65 ℃ of distillation tower top temperature, and column bottom temperature is 145 ℃.What the tower still came out is the thick liquid of dimethyl oxalate (0.8kg/h), the methylcarbonate that cat head comes out and the azeotrope of methyl alcohol (flow is 0.8kg/ hour), after being pressurized to 4MPa, enter pressurization knockout tower 5 (internal diameter 30mm, height 3000mm) in, about 155 ℃ of pressurization tower top temperature, column bottom temperature is 205 ℃.What come out at the bottom of the tower is that purity is 98.8% methylcarbonate product (flow is 0.32kg/ hour).
After the lime set that contains ethyl glycolate (0.04kg/h) that thick liquid of dimethyl oxalate (0.8kg/h) and the rectifying tower 11 that the tower still of distillation tower 4 comes out comes out is mixed, again after being pressurized to 3MPa, with gas (74% hydrogen that is heated to 200 ℃, 25.2% nitrogen, pressure 3MPa) after the mixing, join (internal diameter 43mm, height 1500mm loads 1.2 liters of solid hydrogenation catalysts) in the reactor 7 as raw material.
The gas that reactor 7 comes out enters condenser 9 (internal diameter 55mm, height 1500mm), is cooled to 40 ℃.The condensate flow that comes out in condenser bottom is that (weight consisted of: 22.1% ethylene glycol in 0.92kg/ hour, 75.9% methyl alcohol, 1.8% ethyl glycolate), on the other hand, eject next noncondensable gas (9400 liters/hour of flows from condenser, volume is formed: 73.8% hydrogen, 26.2% nitrogen) as the hydrogen feed recycling.The lime set that condenser 9 comes out (flow 0.92kg/ hour) imports in the pre-distillation column 10 (internal diameter 30mm, height 3000mm), about 65 ℃ of fore-distillation cat head temperature, and column bottom temperature is 158 ℃.The methyl alcohol that cat head steams is back to regenerator column utilization (0.7 liter/hour of flow) as the recirculation material.On the other hand, the heavy constituent that obtain at the bottom of the tower (flow is 0.52kg/ hour, and weight consists of 91.8% ethylene glycol, 7.1% ethyl glycolate) enter into rectifying tower 11 (internal diameter 30mm, height 3000mm), about 95 ℃ of cat head controlled temperature, and column bottom temperature is 158 ℃.The ethyl glycolate that cat head comes out (flow is 0.04kg/ hour), recirculation turns back in the reactor 7, and on the other hand, what come out at the bottom of the tower is that purity is 98.9% ethylene glycol product (flow is 0.48kg/ hour).
Claims (10)
1. the continuous preparation process of ethylene glycol and methylcarbonate is made up of following process:
(1) the first step: the gas that contains CO and methyl nitrite is under gas phase state, and temperature of reaction is 50～200 ℃, and pressure is under the condition of 0～1MPa, contacts with platinum metal catalysts and reacts, and is mainly contained the product of dimethyl oxalate and methylcarbonate;
(2) second steps: the product that the first step reaction process is come out carries out condensation, and the non-condensable gas that contains NO that said process is generated is separated from the phlegma that contains dimethyl oxalate and methylcarbonate;
(3) the 3rd steps: the non-condensable gas that in regenerator column the second step process is obtained contacts with oxygen and alcohol and reacts, the product that generates comprises methyl nitrite and unreacted NO, the volumetric concentration of NO will be controlled at 1～10%, and the gaseous mixture circulation that again this is contained methyl nitrite turns back in the first step;
(4) the 4th steps: the phlegma that contains dimethyl oxalate and methylcarbonate that second step was obtained distills, and what come out at the bottom of the tower is dimethyl oxalate, and what cat head came out is the azeotrope of methyl alcohol and methylcarbonate; Methyl alcohol enters the pressure distillation tower with methylcarbonate to be separated, and what obtain at the bottom of the tower is the methylcarbonate product, and the methyl alcohol that cat head obtains one of is originated as the methanol feedstock of three-step reaction;
(5) the 5th steps: the dimethyl oxalate that the 4th step process distillation tower still is obtained carries out catalytic hydrogenation reaction under gas phase state, obtain containing the product of ethylene glycol;
(6) the 6th steps: the product to the 5th step process gained carries out fore-distillation, obtains product ethylene glycol after methyl alcohol is separated; Separating the methyl alcohol that obtains one of originates as the methanol feedstock of three-step reaction.
2. in the method according to claim 1, it is characterized in that the first step oxidative coupling reaction temperature is 50～200 ℃, pressure is 0～1Mpa.
3. in the method according to claim 1, it is characterized in that the 5th step catalytic hydrogenation reaction temperature is 150～350 ℃, pressure is 1～4MPa.
4. in the method according to claim 1, it is characterized in that the used catalyzer of the first step oxidative coupling reaction is loaded on the aluminum oxide by palladium metal or its esters.
5. in the method according to claim 1, it is characterized in that the used catalyzer of the 5th step catalytic hydrogenation reaction is loaded on the aluminum oxide by metallic copper, barium, molybdenum or its esters.
6. in the method according to claim 1, it is characterized in that introduce in the gas of regenerator column in above-mentioned the 3rd step process, the mol ratio of oxygen and NO is 0.05～0.3; The volumetric concentration of leaving the NO of regenerator column will be controlled at 1～10%.
7. in the method according to claim 1, it is characterized in that used quantity of methyl alcohol in the 3rd step process is introduced regenerator column with NO by 1～10: 1 gas volume ratio.
8. in the method according to claim 1, it is characterized in that, before the 4th step process is carried out, the phlegma that must earlier the second step process be obtained distills processing in distillation tower, purpose is that the co-product methylcarbonate elder generation fractionation by distillation that contains is come out, what cat head came out is the azeotrope that methylcarbonate and methyl alcohol form, and the tower still obtains the thick liquid of dimethyl oxalate.
9. according in claim 1, the 8 described methods, it is characterized in that the azeotrope that the distillation tower cat head comes out enters the pressurization knockout tower, the tower still obtains the methylcarbonate product, and the methyl alcohol that recovered overhead obtains is as one of raw material sources of the required methyl alcohol of the 3rd step process.
10. according in the method described in the claim 1, it is characterized in that, in the 6th step process, the by product ethyl glycolate fractionation by distillation that generates in the shortening process come out that recirculation is back to the 5th step hydrogenation process.
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| CN102442903A (en) * | 2010-10-15 | 2012-05-09 | 安徽淮化股份有限公司 | Method for recovering dimethyloxalate and dimethyl carbonate in waste gas during commercial glycol production |
| CN102060664B (en) * | 2010-12-23 | 2012-06-06 | 西南化工研究设计院 | High-efficiency and energy-saving reaction process for preparing ethylene glycol through hydrogenation of oxalate |
| CN102649747B (en) * | 2011-02-25 | 2014-03-26 | 中国石油化工股份有限公司 | Method for producing glycolic acid ester by oxalic ester through fluidized bed reaction |
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