CN1752057A - Method of producing o-xylene - Google Patents
Method of producing o-xylene Download PDFInfo
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- CN1752057A CN1752057A CN 200410066624 CN200410066624A CN1752057A CN 1752057 A CN1752057 A CN 1752057A CN 200410066624 CN200410066624 CN 200410066624 CN 200410066624 A CN200410066624 A CN 200410066624A CN 1752057 A CN1752057 A CN 1752057A
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- xylol
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Abstract
A process for preparing O-ditoluene includes such steps as alkyl transfer reaction between benzene, toluene and C9-C9+x arylhpdrocarbon to obtain mixed ditoluene, separating to obtain high-purity O-ditoluene, further separating to obtain P-ditoluene, and returning the unreacted raw materials back to alkyl transfer unit.
Description
Technical field
The present invention relates to be used to produce the method for o-Xylol, particularly about passing through benzene (Ben), toluene (Tol) and carbon nine and above aromatic hydrocarbons (C thereof earlier
9 +A) aromatic hydrocarbons transalkylation reaction generates C8 aronmatic (C
8A), i.e. Mixed XYLENE logistics separates the method that o-Xylol obtains highly purified o-Xylol product again.
Background technology
O-Xylol is one of important petrochemical industry raw material, in chemical production field purposes is widely arranged.Typical o-Xylol (oX) production method be the dimethylbenzene that contains ethylbenzene of the thermodynamic(al)equilibrium that generates from the petroleum naphtha catalytic reforming be the C8 aronmatic through accurate isolation technique, obtain the o-Xylol product.Because contain more fraction in its C8 aronmatic and o-Xylol overlapping, as C
9, C
10Therefore non-aromatics, is difficult to obtain highly purified high-quality o-Xylol.
For Increasing o-Xylene Output, utilize toluene disproportionation or toluene and carbon nine and above aromatic hydrocarbons (C thereof usually
9 +A) disproportionation and transalkylation reaction generate benzene and C
8A, thereby Increasing o-Xylene Output.
Up to now, in the world more typically, also the technology relevant with toluene disproportionation of comparative maturity has sixties Mo industrialized Tatoray tradition toluene disproportionation process.
The reactor feed of typical Tatoray technology is with toluene and C9 aromatic (C
9A) be reaction raw materials, C
10 +The content of hydrocarbon (carbon ten and above hydrocarbon thereof) must strict control.In order to improve the economic benefit of device, cut down the consumption of energy and material consumption, people have carried out further research and optimization to Tatoray technology, mainly be devoted to its core technology---Study of Catalyst, improve the indicators of overall performance of catalyzer, as improving the molecular-weight average of weight space velocity, prolongation catalyst operation and increase aromatic hydrocarbons reaction raw materials.The raising of molecular-weight average helps increasing C
8A, but when the heavy aromatics too high levels, in order to keep certain transformation efficiency, promptly keep catalyst activity must cause the especially aggravation of hydro-dealkylation reaction of side reaction, thereby makes in the reaction product benzaldehyde product on the high side, causes product C
8A/Ben is on the low side, and the aromatic hydrocarbons loss is bigger, handles equal raw material, the C that obtains
8A is on the low side, the Ben amount is on the high side.
Document based on Tatoray technology has USP4341914, Chinese patent 98110859.8, USP2795629, USP3551510, Chinese patent 97106719.8 etc.In the USP4341914 technical process, though with the portion C in the reaction product
10A is with circulation C
9A returns reaction zone (logistics 18), the C that has partly utilized reaction itself to generate
10A comes to generate in the inhibited reaction process more substantial C
10 +Hydrocarbon, still, raw material C
8 +C among the A
10 +Hydrocarbon but can't obtain utilizing, and C
8 +Portion C in the A raw material
9A is with C
10 +Hydrocarbon is discharged out-of-bounds (logistics 19) at heavy aromatics Tata still.Because the restriction of catalyst performance, this technology also has exacting terms in the selection of raw material, require heavy aromatics tower (tower 2) cat head effluent---C
9Indane (IND) content in the A logistics (logistics 7) must be lower than below 1%, thereby has caused aforesaid C
9The loss of A and the C that just partly utilizes reaction self to generate
10A, and raw material C
8 +C among the A
10 +Hydrocarbon but can't obtain utilizing.
In the technical process of Chinese patent 98110859.8,, have high indane content, high C in the raw material of permission though this technology has overcome many drawbacks of above-mentioned patent
10 +Advantages such as hydrocarbon content, but still a large amount of benzene of by-product.
Summary of the invention
Technical problem to be solved by this invention is carbon ten and the low problem of above heavy aromatics content thereof in a large amount of benzene of by-product, the raw material when exist producing o-Xylol in the conventional art, and a kind of new method that is used to produce o-Xylol is provided.This method has that separation process is simple, and plant energy consumption is low, significantly the characteristics of Increasing o-Xylene Output throughput.
For solving the problems of the technologies described above, the technical solution used in the present invention is as follows: a kind of method that is used to produce o-Xylol may further comprise the steps successively:
A) benzene that out-of-bounds comes, toluene and C
9A and above aromatic hydrocarbons thereof enter the alkyl transfering process unit that contains the molybdenum molecular sieve catalyst, carry out the aromatic hydrocarbons transalkylation reaction under hydro condition, and the reaction back generates and contains the logistics that mixes dimethylbenzene;
B) separating step contains in a) and mixes the dimethylbenzene logistics, obtains highly purified o-Xylol;
C) the xylol logistics behind the separation o-Xylol goes the fractionation by adsorption isomerization unit to produce p-Xylol, unreacted benzene, toluene and C
9A and above aromatic hydrocarbons thereof are circulated in the alkyl transfering process unit feed.
Benzene, toluene and C in the technique scheme
9A and above aromatic hydrocarbons thereof carry out the aromatic hydrocarbons transalkylation reaction containing on the molybdenum molecular sieve catalyst, the molecular sieve preferred version in the used molecular sieve catalyst is selected from mordenite, β zeolite or omega zeolite; The unitary operational condition of alkyl transfering process: reaction pressure is 1～4MPa, and temperature of reaction is 300～480 ℃, and hydrogen/hydrocarbon mol ratio is 0.5～10, and weight space velocity is 0.8～8 hour
-1In the separation process of xylol logistics deheptanizer is set; The isolating C of deheptanizer cat head
7And following hydrocarbon is circulated in the alkyl transfering process unit feed, and tower still carbon eight and above aromatic hydrocarbons thereof enter benzenol hydrorefining.The benzenol hydrorefining of separating mixed dimethyl logistics, its cat head extraction C8 aronmatic logistics, the extraction of tower still contains the carbon nine and the above arene stream thereof of o-Xylol, preferred version is the logistics of benzenol hydrorefining cat head extraction C8 aronmatic, the extraction of tower still contains the carbon nine and the C10 aromartic logistics of o-Xylol, and this logistics enters ortho-xylene column; O-Xylol column overhead extraction o-Xylol product, the carbon nine and the above aromatic hydrocarbons thereof of the extraction of tower still side line are circulated in the alkyl transfering process unit feed, extraction of tower still or not extraction carbon 11 and above heavy aromatics (C thereof
11 +Hydrocarbon); Contain in the molybdenum molecular sieve catalyst, the consumption of molybdenum or its oxide compound is 0.05～10.0% by weight percentage.
O-Xylol Tata still produced quantity described in the such scheme is means of control technique unit raw material molecular-weight average of the present invention.In the normal running, not extraction of tower still C
11 +Hydrocarbon is to increase production more o-Xylol and p-Xylol; Have only when catalyzer be in the latter stage in operational cycle and be difficult to synchronous situation of factory's turnaround under, can be by the extraction portion C
11 +Hydrocarbon reducing the raw material molecular-weight average of this technique unit, thereby reduces the severity of reaction, makes this unitary operation not influence the turnaround plans of factory.
The extraction of o-Xylol in the technique scheme for whole Aromatic Hydrocarbon United Plant, also is the effective means that increases p-Xylol output.Owing to separated the o-Xylol of quite a few in the Mixed XYLENE, make the concentration of the p-Xylol in the fractionation by adsorption charging be improved, thereby increased the production capacity of p-Xylol.
In the technique scheme, be to generate after the catalyzed reaction through macro-porous zeolite catalysts such as mordenite, β zeolite or omega zeolites, make boiling range and o-Xylol eclipsed C owing to be used to produce the arene stream of o-Xylol
9, C
10The content of non-aromatics significantly reduces, and has reduced the difficulty of separating o-Xylol, and the rate of recovery of o-Xylol is reached more than 50%, has improved the output of o-Xylol effectively.
As can be seen, such operational path makes the aromatic hydrocarbons of carbon more than six all be transformed into the o-Xylol and the p-Xylol of high added value, has simplified separation process effectively, has fully reduced the energy consumption material consumption of aromatic device.
In technology of the present invention, the aromatic hydrocarbons transalkylation reaction is different with traditional transalkylation notion, and it is with benzene, toluene and carbon nine and above aromatic hydrocarbons (C thereof
9 +A) be raw material, reaction generates C
8A.Because benzene and heavy aromatics be also as producing the raw material of Mixed XYLENE, thereby under the constant situation of reformation scale, just can improve the throughput of p-Xylol and o-Xylol significantly.
In the inventive method with benzene, toluene and C
9 +A is that raw material is produced p-Xylol, because in the technology of the present invention, benzene and C
10And above aromatic hydrocarbons need not be separated from reaction effluent, thereby simplified separation process significantly, can save the necessary stripping tower of typical Tatoray technology separating reaction effluent, benzene tower and heavy aromatics tower, only need make toluene tower into deheptanizer, and keep benzenol hydrorefining and ortho-xylene column gets final product.Six original tower separation systems are simplified to three tower separation systems, therefore, have reduced the energy consumption of device significantly, reduced production cost effectively.Simultaneously because benzene and all C
10And above heavy aromatics can be used as reaction raw materials, and Increasing o-Xylene Output throughput has obtained better technical effect significantly.
Description of drawings
Fig. 1 is the technical process of US4341914.
Fig. 2 is the technical process of Chinese patent 98110859.8.
Fig. 3 is used to produce the alkyl transfering process flow process of o-Xylol for the present invention.
Among Fig. 1,1 is benzenol hydrorefining I, and 2 is the heavy aromatics tower, and 3 is reaction zone, and 4 is the benzene tower, and 5 is toluene tower, and 6 is benzenol hydrorefining II, and 7 is C
9A, 8 is C
8 +The A raw material, 9 and 10 is toluene, and 11 is benzene, and 12 and 13 is C
8A, 17 and 19 for being rich in C
10 +Hydrocarbon stream, 18 for being rich in C
9The A logistics.
1 is benzenol hydrorefining I among Fig. 2, and 2 is the heavy aromatics tower, and 3 is reaction zone, and 4 is the benzene tower, and 5 is toluene tower, and 6 is benzenol hydrorefining II, and 7 is ortho-xylene column, and 8 is C
8 +The A raw material, 9 is fresh toluene, 12 and 13 is C
8A, 14 for being rich in C
9The A logistics, 15 is carbon 11 and above hydrocarbon (C thereof
11 +Hydrocarbon), 16 are circulation toluene, and 17 is benzene, and 19 is o-Xylol, and 20 for containing or do not contain the C of o-Xylol
9 +A.
1 is the raw hydrogen, benzene, toluene and the C that out-of-bounds come among Fig. 3
9And above aromatic hydrocarbons, 2 aromatic hydrocarbons transalkylation reaction of the present invention unit, 3 is deheptanizer, and 4 is benzenol hydrorefining, and 5 is ortho-xylene column, and 6 is round-robin C
7And following hydrocarbon, 7 is C
8And above hydrocarbon, 8 is Mixed XYLENE product, i.e. C
8Aromatic hydrocarbons, 9 for not containing the C that m-xylene contains o-Xylol
9And above aromatic hydrocarbons, 10 is the o-Xylol product, 11 is C
11And above aromatic hydrocarbons, 12 is round-robin C
9And above aromatic hydrocarbons.
From benzene, toluene and the C that out-of-bounds comes
9And isolated C in above aromatic hydrocarbons 1 and the reaction effluent
7And following hydrocarbon 6 and C
9And above aromatic hydrocarbons 12 and hydrogen enters aromatic hydrocarbons transalkylation reaction of the present invention unit 2 after mixing and carries out the aromatic hydrocarbons transalkylation reaction, generates Mixed XYLENE, and reaction effluent separates through deheptanizer, the isolated C of cat head
7And following hydrocarbon 6 is circulated in the reaction feed, and extraction is rich in C at the bottom of the tower
8 +Benzenol hydrorefining 4 is advanced in A logistics 7, and the Mixed XYLENE logistics 8 of cat head extraction, the extraction of tower still do not contain m-xylene and contain the C of o-Xylol
9And above arene stream 9, this logistics enters ortho-xylene column 5, at the highly purified o-Xylol product of o-Xylol column overhead output, and tower bottom side line extraction C
9And above aromatic hydrocarbons 12, this logistics is circulated in the reaction feed, extraction of tower still or not extraction C
11 +Hydrocarbon 11.
The invention will be further elaborated below by embodiment.
Embodiment
[embodiment 1～4]
Under the hydro condition, in fixed-bed reactor, carry out benzene, toluene and C
9 +A transalkylation reaction performance is investigated.25 millimeters of reactor inside diameter φ, 1000 millimeters of length, stainless steel.The equal up and down 3 millimeters granulated glass spherees of filling φ of beds play air-flow and distribute and supporting role, and filling 20 grams contain the molecular sieve catalyst of molybdenum in the reactor.Aroamtic hydrocarbon raw material with after hydrogen mixes from top to bottom by beds, carry out benzene, toluene and C
9 +The transalkylation reaction of A generates C
8A, i.e. Mixed XYLENE.
Benzene feedstock, toluene and C
9 +A derives from petrochemical complex Aromatic Hydrocarbon United Plant, H
2Be electrolysis hydrogen, through dehydrating processing, reaction result is listed in the table 1.
The purity of o-Xylol product can be calculated with following method:
The concentration of o-Xylol in the purity=reaction product of o-Xylol/(concentration of o-Xylol and C in the reaction product
9, C
10Non-aromatics concentration sum)
Data can draw from table, and the purity of the o-Xylol product that technology of the present invention obtains is respectively:
The o-Xylol product purity of embodiment 1 is 99.34%;
The o-Xylol product purity of embodiment 2 is 99.35%;
The o-Xylol product purity of embodiment 3 is 99.36%;
The o-Xylol product purity of embodiment 4 is 99.36%.
Table 1 benzene, toluene and C9 aromatic transalkylation reaction raw material and product compositional analysis (1～4)
| Embodiment | 1 | 2 | 3 | 4 | |
| Molecular sieve | A 0.4 325 1.5 0.8 3 | B 1.2 345 1.5 1.3 2 | B 3.8 400 4 4.5 8.5 | A 5.7 420 4 6 10 | |
| Weight of molybdenum content, the % temperature of reaction, ℃ reaction pressure, the MPa weight space velocity, hour -1Hydrogen/hydrocarbon mol ratio | |||||
| Reaction raw materials is formed weight % | C 1～C 5NA Ben Tol C 8A C 9NA C 10NA C 9A IND C 10 +Hydrocarbon | 0.01 73.48 0.01 0.06 0.50 0.50 19.13 0.61 5.70 | 0.01 39.00 34.50 0.06 0.40 0.60 18.63 0.61 6.19 | 0.10 18.90 54.60 0.06 0.60 0.40 18.63 0.61 6.10 | 0.10 14.07 59.29 0.09 0.80 0.70 18.32 0.53 6.10 |
| Reaction product is formed weight % | NA Ben Tol pX mX oX C 9NA C 10NA C 9A C 10 +Hydrocarbon | 2.51 49.57 25.72 2.96 7.12 3.03 0.01 0.01 5.83 3.23 | 4.01 29.70 29.98 6.01 14.44 6.14 0.02 0.02 6.07 3.60 | 5.51 16.48 32.90 7.59 18.25 7.75 0.03 0.02 7.18 4.28 | 5.24 13.02 34.90 7.62 18.31 7.78 0.02 0.03 8.03 5.06 |
| O-Xylol purity, % | 99.34 | 99.35 | 99.36 | 99.36 | |
Annotate: the A representative contains the molybdenum filament geolyte; The B representative contains molybdenum β zeolite; NA is a non-aromatics; PX is a p-Xylol; MX is a m-xylene; OX is an o-Xylol.
From embodiment 1～4 as can be seen: benzene, toluene and C the raw material
9A and C
10 +After reacting, generated C
8A.C9, C10 non-aromatics are cracked into the lightweight non-aromatics through zeolite catalyst catalyzed reaction back end hydrogenation in the raw material, thereby the purity of o-Xylol is improved, and can obtain highly purified o-Xylol product.
By as seen above-mentioned, the method that patent of the present invention provides a kind of brand-new more economical being used to produce o-Xylol and can produce p-Xylol simultaneously.
Claims (7)
1, a kind of method that is used to produce o-Xylol may further comprise the steps successively:
A) benzene that out-of-bounds comes, toluene and C
9A and above aromatic hydrocarbons thereof enter the alkyl transfering process unit that contains the molybdenum molecular sieve catalyst, carry out the aromatic hydrocarbons transalkylation reaction under hydro condition, and the reaction back generates and contains the logistics that mixes dimethylbenzene;
B) separating step contains in a) and mixes the dimethylbenzene logistics, obtains highly purified o-Xylol;
C) the xylol logistics behind the separation o-Xylol goes the fractionation by adsorption isomerization unit to produce p-Xylol, unreacted benzene, toluene and C
9A and above aromatic hydrocarbons thereof are circulated in the alkyl transfering process unit feed.
2, according to the described method that is used to produce o-Xylol of claim 1, it is characterized in that the benzenol hydrorefining of separating mixed dimethyl logistics, its cat head extraction C8 aronmatic logistics, the extraction of tower still contains the carbon nine and the above arene stream thereof of o-Xylol.
3, according to the described method that is used to produce o-Xylol of claim 1, it is characterized in that the unitary operational condition of alkyl transfering process: reaction pressure is 1～4MPa, temperature of reaction is 300～480 ℃, and hydrogen/hydrocarbon mol ratio is 0.5～10, and weight space velocity is 0.8～8 hour
-1
4,, it is characterized in that in the separation process of xylol logistics deheptanizer, benzenol hydrorefining and ortho-xylene column three-tower system being set according to the described method that is used to produce o-Xylol of claim 1; The isolating C of deheptanizer cat head
7And following hydrocarbon is circulated in the alkyl transfering process unit feed, and tower still carbon eight and above aromatic hydrocarbons thereof enter benzenol hydrorefining.
5,, it is characterized in that molecular screening in the employed molecular sieve catalyst is from mordenite, β zeolite or omega zeolite according to the described method that is used to produce o-Xylol of claim 1.
6, according to the described method that is used to produce o-Xylol of claim 2, it is characterized in that the logistics of benzenol hydrorefining cat head extraction C8 aronmatic, the extraction of tower still contains the carbon nine and the C10 aromartic logistics of o-Xylol, and this logistics enters ortho-xylene column; O-Xylol column overhead extraction o-Xylol, the carbon nine and the above aromatic hydrocarbons thereof of the extraction of tower still side line are circulated in the alkyl transfering process unit feed extraction of tower still or not extraction carbon 11 and above heavy aromatics thereof.
7, according to the described method that is used to produce o-Xylol of claim 1, the consumption that it is characterized in that containing in the molybdenum molecular sieve catalyst molybdenum by weight percentage or its oxide compound is 0.05～10.0%.
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|---|---|---|---|
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|---|---|---|---|
| CNB200410066624XA CN100368361C (en) | 2004-09-24 | 2004-09-24 | Method of producing o-xylene |
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| CN100368361C CN100368361C (en) | 2008-02-13 |
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