CN103467238A - Production method for p-xylene - Google Patents
Production method for p-xylene Download PDFInfo
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- CN103467238A CN103467238A CN2013103732505A CN201310373250A CN103467238A CN 103467238 A CN103467238 A CN 103467238A CN 2013103732505 A CN2013103732505 A CN 2013103732505A CN 201310373250 A CN201310373250 A CN 201310373250A CN 103467238 A CN103467238 A CN 103467238A
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Abstract
The invention relates to a production method for p-xylene. The production method comprises the following steps: alkylation reaction using benzene, toluene and methanolas raw materials and processes of toluene recycling and xylene extraction for products of the alkylation reaction in sequence. The production method is characterized in that residual C9 of extracted xylene, aromatic matters, and mixed raw materials of benzene and toluene being subjected to steam dealkylation reaction are subjected to transalkylation reaction firstly, and then the processes of toluene recycling and xylene extraction. According to the invention, based on the prior art, part of raw materials of benzene and toluene are produced into benzene high concentration through a steam dealkylation reactor; through the utilization of the transalkylation reaction, C9 at the xylene tower bottom and arene are allowed to take part in the reaction; the reaction is promoted to be conducted in the direction of the production of dimethyl benzene in an equilibrating manner; the concentration of p-xylene is increased; the per pass conversion of p-xylene is improved. Through the adoption of the production method, the concentration of p-xylene can be allowed to improve by 15-20% (w), and the conversion rate of benzene and toluene is improved by 5-10%.
Description
Technical field
The invention belongs to the petrochemical technology field, particularly relate to a kind of production method of p-Xylol.
Background technology
P-Xylol (PX) is one of main organic raw material of petrochemical industry, in numerous chemical production field such as chemical fibre, synthetic resins, agricultural chemicals, medicine, plastics, purposes is widely arranged, and is mainly used in synthetic pure terephthalic acid (PTA).Typical p-Xylol production method is by multistage cryogenic crystallization, to separate or molecular sieve simulated moving bed adsorption separation (abbreviation fractionation by adsorption) technology the xylol (C8A) of the thermodynamic(al)equilibrium that generates from the petroleum naphtha catalytic reforming, and p-Xylol is separated close isomer mixture with it from boiling point.Be subject to the impact of thermodynamic(al)equilibrium, in xylol, usually the content of m-xylene (MP) is higher, and the larger PX content of industrial water requirement is lower, usually adopts the technique means volume increase PX such as toluene disproportionation and transalkylation, C8 aromatics isomerization so industrial.The PX product purity can reach more than 98%, but yield is the highest, only has 70% left and right.
In recent years, along with the swift and violent increase of pure terephthalic acid's production capacity, China presents the p-Xylol situation that supply falls short of demand, price is high.Become the focus of people's research by benzene, toluene and methanol alkylation dimethylbenzene processed, as Chinese patent.The synthetic dimethylbenzene of toluene, methanol alkylation is a new operational path of increasing yield of p-xylene, for toluene transforms and cheap methyl alcohol utilization provides new approach.
Summary of the invention
Purpose of the present invention just is to provide a kind of brand-new method that benzene, toluene is the raw material production p-Xylol of take.
Technical scheme of the present invention is:
A kind of production method of p-Xylol, the method comprises take alkylated reaction that benzene, toluene and methyl alcohol is raw material and alkylation reaction product is carried out to toluene recovery and dimethylbenzene abstraction process successively, it is characterized in that: after the carbon nine left behind after described dimethylbenzene is extracted and above aromatic hydrocarbon substance are carried out transalkylation reaction with benzene through the water vapour dealkylation and toluene mixing raw material, then carry out successively above-mentioned toluene recovery and dimethylbenzene abstraction process.
Described alkylation reaction condition is: reactor pressure 0.05 ~ 0.8MPa, 400 ~ 450 ℃ of raw material feeding temperatures, toluene and methanol 2 ~ 6mol/mol, toluene/benzene>=1.5mol/mol, total weight of material air speed≤1.2h
-1.
Described raw material toluene derives from the toluene recovery operation.
Described water vapour dealkylation adopts water vapour as reagent, adds a small amount of alkali and alkaline-earth metal in catalyzer as promotor.
Described water vapour dealkylation condition is: 590 ~ 650 ℃ of temperature of reaction, total weight of material air speed 2 ~ 4 h
-1, reactor pressure 5.5 ~ 6.5MPa.
Described transalkylation reaction conditions is: pressure 2.8 ~ 3.2MPa, 380 ~ 430 ℃ of bed temperatures, weight space velocity 2.0 ~ 3.5h
-1.
Take alkylated reaction that benzene, toluene and methyl alcohol is raw material and alkylation reaction product is carried out to toluene recovery successively and the dimethylbenzene abstraction process can be referring to patent application " a kind of method and device by benzene, toluene and methanol alkylation dimethylbenzene processed " (application number: CN201210233169.2) in the present invention.
The present invention on the basis of existing technology, a part of benzene, methylbenzene raw material are generated to high density benzene by water vapour dealkylation device, at the bottom of utilizing transalkylation reaction by benzenol hydrorefining, carbon nine and above aromatic hydrocarbons attend fully are in reaction, promoted that molecular balance carries out to the direction that generates dimethylbenzene, increase the concentration of p-Xylol, improved the p-Xylol per pass conversion.Method of the present invention, can make the concentration of p-Xylol improve 15～20%(w), the transformation efficiency of benzene and toluene improves 5～10%.
Simultaneously, in the present invention, the synthetic gas of dealkylation device top output can pass through the high-pressure process synthesizing methanol, returns to methanol evaporator and supplements raw material, takes full advantage of carbon nine and above aromatic hydrocarbons material, also can set up the PSA device, purification H
2, for needing hydrogen unit hydrogen supply, increased the handiness of device operation and the diversity of product, there is application prospect preferably.
The accompanying drawing explanation
Fig. 1 is the technical process that p-Xylol of the present invention is produced.
Wherein, I is benzene-toluene evaporates device; II is alkylation reactor; III is methanol evaporator; IV is the toluene recovery tower; V is toluene recovery tower top complete condenser; VI is benzenol hydrorefining; VII is dimethylbenzene tower top complete condenser; VIII is water vapour dealkylation device; IX is transalkylation reactor; X is adsorption separation unit.
1 is aroamtic hydrocarbon raw material (benzene of arbitrary proportion and toluene.); 2 is toluene; 4 is methanol steam; 5 is methyl alcohol; 6 is the discharging of toluene recovery column overhead; 7 is the alkylation reactor bottom discharge; 8 is the discharging of toluene recovery tower bottom; 9 is the discharging of benzenol hydrorefining tower top; 10 is xylol; 11 is the xylene column bottoms discharging; 12 is transalkylation reaction product; 13 is benzene, methylbenzene raw material; 14 is the dealkylation bottom discharge; 15 is synthetic gas (CO, CO
2, H
2); 16 is p-Xylol.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in detail.
As shown in Figure 1, the toluene 2 that aroamtic hydrocarbon raw material 1 and toluene tower top complete condenser V are extracted out is incoming stock vaporizer I together, the methanol steam 4 that mixed gaseous benzene out, toluene reach from the methanol evaporator III out together enters the alkylation reactor II, reactor pressure 0.05～0.8MPa, 400～450 ℃ of temperature ins, toluene and methanol: 2～6mol/mol, toluene/benzene:>=1.5mol/mol, total weight of material air speed≤1.2h
-1.Reactor bottom discharging 7 enters toluene recovery tower IV, and tower top is regained toluene 2 and returns to the feed vaporizer I by the complete condenser V.Toluene recovery tower IV bottom discharge 8 enters the benzenol hydrorefining VI, pressure 0.8～1.0 MPa(G), 245～255 ℃ of temperature, 260～290 ℃ of column bottom temperatures, reflux ratio 3.5～4.5(weight ratio), tower top discharging 9, after the condensation of complete condenser VII, enters adsorption separation unit with liquid form 10, obtains p-Xylol 16.
Part raw material 13(benzene and toluene) while with water vapour, being heated to 590 ~ 650 ℃, enter water vapour dealkylation device VIII, the rhodium that the aluminum oxide of take is carrier is catalyzer, a small amount of alkali and alkaline-earth metal carry out the de-alkyl of water vapour as promotor.Total weight of material air speed 2 ~ 4 h
-1, reactor pressure 5.5 ~ 6.5MPa.
Dealkylation bottom discharge 14(high density benzene) with benzenol hydrorefining VI bottom discharge 11(carbon nine and above aromatic hydrocarbon substance) in the transalkylation reactor IX, react, weight space velocity 2.0～3.5 h
-1, pressure 2.8～3.2 MPa(G), 380～430 ℃ of bed temperatures, transalkylation reaction product 12 returns to toluene recovery tower IV, proceeds to separate, and finally obtains p-Xylol 16.
Water vapour dealkylation device VIII top gas 15 can enter methanol synthesizer or hydrogen purification device according to the actual needs of device associating.
Claims (6)
1. the production method of a p-Xylol, the method comprises take alkylated reaction that benzene, toluene and methyl alcohol is raw material and alkylation reaction product is carried out to toluene recovery and dimethylbenzene abstraction process successively, it is characterized in that: after the carbon nine left behind after described dimethylbenzene is extracted and above aromatic hydrocarbons carry out transalkylation reaction with benzene through the water vapour dealkylation and toluene mixing raw material, then carry out successively above-mentioned toluene recovery and dimethylbenzene abstraction process.
2. according to the production method of p-Xylol claimed in claim 1, it is characterized in that described alkylation reaction condition is: reactor pressure 0.05 ~ 0.8MPa, 400 ~ 450 ℃ of raw material feeding temperatures, toluene and methanol 2 ~ 6mol/mol, toluene/benzene>=1.5mol/mol, total weight of material air speed≤1.2h
-1.
3. according to the production method of claim 1 or 2 described p-Xylol, it is characterized in that described raw material toluene derives from the toluene recovery operation.
4. according to the production method of p-Xylol claimed in claim 1, it is characterized in that described water vapour dealkylation adopts water vapour as reagent, add a small amount of alkali and alkaline-earth metal in catalyzer as promotor.
5. as the production method of claim 1 or 4 described p-Xylol, it is characterized in that described water vapour dealkylation condition is: 590 ~ 650 ℃ of temperature of reaction, total weight of material air speed 2 ~ 4 h
-1, reactor pressure 5.5 ~ 6.5MPa.
6. the production method of a kind of p-Xylol as claimed in claim 1, is characterized in that described transalkylation reaction conditions is: pressure 2.8 ~ 3.2MPa, 380 ~ 430 ℃ of bed temperatures, weight space velocity 2.0 ~ 3.5h
-1.
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|---|---|---|---|
| CN201310373250.5A CN103467238B (en) | 2013-08-23 | 2013-08-23 | A kind of production method of xylol |
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| CN201310373250.5A CN103467238B (en) | 2013-08-23 | 2013-08-23 | A kind of production method of xylol |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5942651A (en) * | 1997-06-13 | 1999-08-24 | Mobile Oil Corporation | Process for converting C9 + aromatic hydrocarbons to lighter aromatic products by transalkylation in the prescence of two zeolite-containing catalysts |
| CN1340489A (en) * | 2000-08-29 | 2002-03-20 | 中国石油化工集团公司 | Process for preparing p-xylene |
| CN102746099A (en) * | 2012-07-06 | 2012-10-24 | 宁夏宝塔石化集团有限公司 | Method and device for preparing dimethylbenzene by alkylating benzene, methylbenzene and methanol |
-
2013
- 2013-08-23 CN CN201310373250.5A patent/CN103467238B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5942651A (en) * | 1997-06-13 | 1999-08-24 | Mobile Oil Corporation | Process for converting C9 + aromatic hydrocarbons to lighter aromatic products by transalkylation in the prescence of two zeolite-containing catalysts |
| CN1340489A (en) * | 2000-08-29 | 2002-03-20 | 中国石油化工集团公司 | Process for preparing p-xylene |
| CN102746099A (en) * | 2012-07-06 | 2012-10-24 | 宁夏宝塔石化集团有限公司 | Method and device for preparing dimethylbenzene by alkylating benzene, methylbenzene and methanol |
Non-Patent Citations (2)
| Title |
|---|
| 秦永宁等: "烷基芳烃催化脱烷基", 《精细石油化工》 * |
| 陈庆龄等: "对二甲苯增产技术发展趋向", 《石油化工》 * |
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