Method by cracking isobutene by methyl-tert-butyl ether
Technical field
The present invention relates to a kind of method by cracking isobutene by methyl-tert-butyl ether, particularly a kind of by the commodity MTBE through take off heavily take off light refining gasification after the method for cracking preparing isobutene, belong to chemical technology field.
Background technology
Iso-butylene is a kind of important chemical material; Be widely used in chemical production field such as butyl rubber, polyisobutene, pesticide intermediate, alkylating aromatic hydrocarbon, methylacrylic acid; New industry such as butyl rubber and high molecular weight polyisobutylene particularly; To iso-butylene require increasingly high; Impel the scientific and technical personnel that are engaged in the work of this field constantly to explore new processing unit, new catalyzer and new process method, produce high-quality iso-butylene product, satisfy the downstream user different demands with low cost.Early stage industrialized sulfuric acid process can be produced two kinds of products of the iso-butylene and the trimethyl carbinol simultaneously, but reason such as, poor product quality serious owing to equipment corrosion, quantity of wastewater effluent be big has withdrawed from production field.The method of trimethyl carbinol dehydration preparing isobutene, the iso-butylene quality is good, can satisfy various users' needs, and following period of time is the main method of preparation iso-butylene.China produced products such as phenolic antioxidant and triisobutyl aluminium originally; Used iso-butylene is produced with this method; States such as the Russia used iso-butylene of production butyl rubber remains so far uses this method to produce, and still has the production equipment of ton to be in operation in the world.The appearance of MTBE synthesis technique has progressively changed this situation.Etherification reaction takes place and generates MTBE under strong acid ionic resin catalyst action in iso-butylene in the mixed c 4 component and methyl alcohol, and this technology transformation efficiency is high; Selectivity is high, less investment, and output is big; Cost is low, for competent raw material is provided by cracking isobutene by methyl-tert-butyl ether.
The method of cracking isobutene by methyl-tert-butyl ether is a lot, can be divided into two kinds of liquid phase method and vapor phase processs substantially.The representative technology of liquid phase method such as gondola Si Namu technology and Chinese Yanshan Petrochemical company technology, its common feature is that transformation efficiency is lower, generally between 80~90%; Temperature of reaction is lower; Generally at 160~230 ℃, selective isobutene is higher, and reaction pressure is higher; Generally about 0.6MPa, in the technological process without compressor.The main drawback of this method is that transformation efficiency is low, and unreacted MTBE needs to recycle, and the methyl alcohol that produces contains a large amount of MTBEs, can only be used as the MTBE synthesis material.Also contain a large amount of MTBEs in the heavy component of iso-butylene weight-removing column, can only be used as fuel, product cost is increased.The representative technology of vapor phase process such as the IFP technology of France and Chinese Inst. of Jilin Chemical Industry Co technology, this method is because transformation efficiency is high, and selectivity is high; Good product quality; Cost is low, need not rely on the MTBE synthesizer, can near the user, found the factory nearby; Raw material can be purchased from market, has therefore obtained developing rapidly.But this method and people's expectation also has a certain distance, rests on for a long time between 98~99% like transformation efficiency, and selectivity is about 99%, and the liquid phase air speed is less than 1h
-1Etc. problem, perplexing the related personnel for a long time.Number of patent application is 200610041851.6 through changing the catalyst activation condition, has improved the transformation efficiency and the selectivity of catalyzer, has obtained certain progress.But this technology liquid phase air speed is 0.5~0.75h
-1The product iso-butylene is not refining; Can not satisfy the needs of high-end user, be not industrial development direction, and particularly the formulation about " it also is thermo-negative reaction that the side reaction that generates DME of dewatering between DIB and methanol molecules is produced in the IB polymerization " is inaccurate in this patent; Be easy to generate the misleading effect, be unfavorable for the progress of iso-butylene production technology.
The transformation efficiency of MTBE scission reaction and selectivity are the standards of weighing the state of the art height.On single numeral that is more or less the same from the transformation efficiency and the selectivity of scission reaction; Influence is not very big on the performance yield; But unreacted MTBE and by product all will remove in the product purification process; Will carry a large amount of iso-butylenes secretly in the process that removes, foreign matter content is high more to be carried secretly manyly more, makes the true yield of iso-butylene reduce a lot.
Summary of the invention
The object of the present invention is to provide a kind of method by cracking isobutene by methyl-tert-butyl ether, throughput is big, transformation efficiency is high, selectivity is high, cost is low, good product quality.
The present invention is on the basis of existing gas-phase process, through improving the structure of cracking reactor, adopts new catalyzer, and the optimization technical process realizes.
Method by cracking isobutene by methyl-tert-butyl ether of the present invention adopts a kind of novel trundle bed reactor drum, novel high-activity catalyzer and " anti-five towers " technical process to carry out, wherein:
Novel trundle bed reactor drum is meant the shell-and-tube reactor of 1~3.5 meter of pipe range;
The novel high-activity catalyzer is meant with dripping the moulding of ball method, bulk density 0.4~0.5g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm;
Comprise in " anti-five towers " technical process that a cracker, the refining gasification of MTBE tower, a water-cooled wash pure tower, a methanol rectifying tower, an iso-butylene weight-removing column and an iso-butylene lightness-removing column, water-cooled is washed alcohol and in same tower, is accomplished.
Specific practice is: adopt a kind of novel trundle bed reactor drum, adopt a kind of low density, high activated catalyst, scission reaction is carried out with having in the presence of the water vapour at lower pressure, form " anti-five towers " technical process.Method provided by the invention, liquid phase air speed 4~7h
-1, transformation efficiency is greater than 99.5%, and selective isobutene is greater than 99.5%, and the iso-butylene product purity can satisfy the specification of quality of high-end markets such as butyl rubber and high molecular weight polyisobutylene to iso-butylene greater than 99.95%.
Among the present invention:
The MTBE scission reaction is in shell-and-tube reactor, to carry out, and tubulation length is preferably 2~3 meters.
The model of novel high-activity catalyzer is ML-01, and forming method is for dripping the ball method.Controling requirement is liquid phase air speed 4~7h
-1, transformation efficiency is greater than 99.5%, and selective isobutene is greater than 99.5%.
Be added with water in the MTBE scission reaction, the purpose that adds water is in order to suppress side reaction, and the suitable mol ratio of water and MTBE is 0.5~3.0, and reaction pressure is 0.01~0.10MPa, and temperature of reaction is 240~270 ℃.
" anti-five towers " technical process is: the raw material MTBE advances treating tower and removes the weight component; Gas phase MTBE after refining is from the side line extraction; After the high-temperature material heat exchange of cracking reactor outlet; Get into the top of cracking reactor with steam, reaction product is washed pure tower through the laggard water-cooled of heat exchange, washes pure cat head from the pure water of methanol rectifying tower is most of through the laggard water-cooled of cooling; Water-cooled is washed the middle part of the pure water most of (accounting for 70~80%) of pure tower through the laggard entry cold wash alcohol of cooling tower; Another part send methanol rectifying tower, and the thick iso-butylene after the dealcoholysis goes the iso-butylene weight-removing column to remove heavy components such as dipolymer after compressor compresses liquefaction, go the iso-butylene lightness-removing column to remove light component such as water, dme again after; Obtain weight content greater than 99.95% high purity, high quality iso-butylene product, can satisfy the specification of quality of high-end markets such as butyl rubber and high molecular weight polyisobutylene iso-butylene.
Reaction mechanism:
From chemical reaction mechanism; The MTBE cracking is thermo-negative reaction, is 65.2KJ/mol 25 ℃ of gas-phase reaction heat, also is the volume augmenting response simultaneously; One mole MTBE is decomposed into one mole iso-butylene and one mole methyl alcohol; Volume increases and is twice, and therefore, the higher temperature of reaction and the reaction pressure of reduction are favourable to improving transformation efficiency.Its side reaction is that the iso-butylene dimerization generates dipolymer and methanol dehydration generates dme, and side reaction all is thermopositive reaction, and high temperature, high pressure are beneficial to side reaction, and the existence of water can suppress side reaction.From reaction kinetics; Higher MTBE gas line speed has two benefits, and one of which can overcome the diffusional resistance of material on the granules of catalyst outside surface; The MTBE effecting reaction concentration that arrives the granules of catalyst outside surface is improved, increased reaction power; Its two, help overcoming the heat transmission resistance that the granules of catalyst outside surface exists, as early as possible the heat that loses owing to endothermic heat of reaction of make-up catalyst; Improve the temperature of granules of catalyst; Improve speed of response, but too high speed can make pressure fall increase, helps side reaction.The trundle bed shell-and-tube reactor that the present invention adopts has demonstrated fully above-mentioned principle, can give full play to the ability of catalyzer.
The present invention is by the method for cracking isobutene by methyl-tert-butyl ether, and reactor drum throughput improves 5 times, and transformation efficiency is up to more than 99.5%; Selective isobutene is up to more than 99.5%, and reaction process is simple and direct, thorough, and cost is low; The good product quality that obtains; Purity is high, and weight content can satisfy the specification of quality of high-end markets such as butyl rubber and high molecular weight polyisobutylene to iso-butylene up to more than 99.95%.
Description of drawings
Fig. 1, process flow diagram of the present invention.
Embodiment
Below in conjunction with embodiment the present invention is described further.
Method by cracking isobutene by methyl-tert-butyl ether of the present invention, raw material MTBE are advanced treating tower and are removed the weight component, and the gas phase MTBE after making with extra care is from the side line extraction; After the high-temperature material heat exchange of cracking reactor outlet; Get into the top of cracking reactor with steam, reaction product is washed pure tower through the laggard water-cooled of heat exchange, washes pure cat head from the pure water of methanol rectifying tower still is most of through the laggard water-cooled of cooling; Water-cooled is washed the most of middle part through the laggard entry cold wash alcohol of cooling tower of pure water of pure tower; Another part send methanol rectifying tower, and the thick iso-butylene after the dealcoholysis removes the iso-butylene weight-removing column after compressor compresses liquefaction, remove the dipolymer heavy component; Go lightness-removing column to remove light component such as water, dme again, obtain the high-purity isobutylene product.
Embodiment 1
The MTBE scission reaction is carried out in the trundle bed shell-and-tube reactor, and tubulation length is 3.5 meters, selects the ML-01 catalyzer for use, bulk density 0.5g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm, the catalyst bed layer height is 2 meters, temperature of reaction is 240~270 ℃, reaction pressure is 0.08MPa, the mol ratio of water and MTBE is 1.0, other operational condition and result see table 1.
Table 1, operational condition and result
Project |
Unit |
The result |
The water ratio |
Mol ratio |
1 |
The liquid air speed |
h
-1 |
5.69 |
Temperature in |
℃ |
254 |
Temperature out |
℃ |
259 |
Transformation efficiency |
% |
99.72 |
Selective isobutene |
% |
99.75 |
The methyl alcohol selectivity |
% |
99.10 |
Embodiment 2, MTBE scission reaction are carried out in the trundle bed shell-and-tube reactor, and tubulation length is 3.5 meters, select the ML-01 catalyzer for use, bulk density 0.45g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm, the catalyst bed layer height is 2 meters, temperature of reaction is 240~270 ℃, reaction pressure is 0.05MPa, the mol ratio of water and MTBE is 2.0, other operational condition and result see table 2.
Table 2, operational condition and result
Project |
Unit |
The result |
The water ratio |
Mol ratio |
2.0 |
The liquid air speed |
h
-1 |
5.69 |
Temperature in |
℃ |
256 |
Temperature out |
℃ |
260 |
Transformation efficiency |
% |
99.73 |
Selective isobutene |
% |
99.80 |
The methyl alcohol selectivity |
% |
99.05 |
Comparative example 1
The MTBE scission reaction is selected the ML-01 catalyzer for use, and the catalyst bed layer height is 5 meters, and temperature of reaction is 240~270 ℃, and reaction pressure is 0.08MPa, and other operational condition and result see table 3.
Table 3, operational condition and result
Project |
Unit |
The result |
The water ratio |
Mol ratio |
1 |
The liquid air speed |
h
-1 |
5.69 |
Temperature in |
℃ |
253 |
Temperature out |
℃ |
262 |
Transformation efficiency |
% |
99.35 |
Selective isobutene |
% |
96.58 |
The methyl alcohol selectivity |
% |
97.50 |
Comparative example 2
The MTBE scission reaction is selected the JHR-02 catalyzer for use, and the catalyst bed layer height is 5 meters, and temperature of reaction is 240~270 ℃, and reaction pressure is 0.08MPa, and other operational condition and result see table 4.
Table 4, operational condition and result
Project |
Unit |
The result |
The water ratio |
Mol ratio |
0 |
The liquid air speed |
h
-1 |
0.75 |
Temperature in |
℃ |
255 |
Temperature out |
℃ |
263 |
Transformation efficiency |
% |
99.26 |
Selective isobutene |
% |
99.18 |
The methyl alcohol selectivity |
% |
99.01 |
Embodiment 3
The MTBE scission reaction is carried out in the trundle bed shell-and-tube reactor, and tubulation length is 3 meters, selects the ML-01 catalyzer for use, bulk density 0.45g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm, the catalyst bed layer height is 2 meters, liquid phase air speed 6h
-1, temperature of reaction is 240~270 ℃, and reaction pressure is 0.06MPa, and the mol ratio of water and MTBE is 3.0.
Embodiment 4
The MTBE scission reaction is carried out in the trundle bed shell-and-tube reactor, and tubulation length is 3 meters, selects the ML-01 catalyzer for use, bulk density 0.4g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm, the catalyst bed layer height is 5 meters, liquid phase air speed 5h
-1, temperature of reaction is 240~270 ℃, and reaction pressure is 0.07MPa, and the mol ratio of water and MTBE is 1.5.
Embodiment 5
The MTBE scission reaction is carried out in the trundle bed shell-and-tube reactor, and tubulation length is 3.5 meters, selects the ML-01 catalyzer for use, bulk density 0.4g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm, the catalyst bed layer height is 2 meters, liquid phase air speed 6h
-1, temperature of reaction is 240~270 ℃, and reaction pressure is 0.09MPa, and the mol ratio of water and MTBE is 2.0.
Embodiment 6
The MTBE scission reaction is carried out in the trundle bed shell-and-tube reactor, and tubulation length is 3 meters, selects the ML-01 catalyzer for use, bulk density 0.4g/cm
3, diameter is the white spherical silicon oxide catalyst series of 3~4mm, the catalyst bed layer height is 3 meters, liquid phase air speed 7h
-1, temperature of reaction is 240~270 ℃, and reaction pressure is 0.08MPa, and the mol ratio of water and MTBE is 2.5.