CN101735000B - Combination method for producing p-xylene - Google Patents
Combination method for producing p-xylene Download PDFInfo
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- CN101735000B CN101735000B CN2008100439757A CN200810043975A CN101735000B CN 101735000 B CN101735000 B CN 101735000B CN 2008100439757 A CN2008100439757 A CN 2008100439757A CN 200810043975 A CN200810043975 A CN 200810043975A CN 101735000 B CN101735000 B CN 101735000B
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Abstract
The invention relates to a combination method for producing p-xylene, which mainly solves the problems of low concentration of p-xylene in mixed xylene, large circulating capacity of processing aromatics, rigorous requirements on reaction raw materials and high energy consumption during the production of the p-xylene in the prior art. In the combination method, a reaction technical scheme that the mixed xylene which contains high-concentration p-xylene and is produced by the selective disproportionation of the methylbenzene and aromatics with 9 and more carbon atoms are subjected to dealkylation reaction to produce combination of benzene, the methylbenzene and the mixed xylene which is in thermodynamic equilibrium, and a separation technical scheme that the high-concentration p-xylene adopts crystallization separation and low-concentration p-xylene adopts combination of adsorption-crystallization separation are adopted to solve the problems better, and the combination method can be used for industrial production of the p-xylene.
Description
Technical field
The present invention relates to a kind of combined method of producing p-Xylol.
Background technology
P-Xylol is one of main basic organic of petrochemical industry, in numerous chemical production field such as chemical fibre, synthetic resins, agricultural chemicals, medicine, plastics, purposes is widely arranged.Typical p-Xylol production method is that the dimethylbenzene that contains ethylbenzene of the thermodynamic(al)equilibrium that generates from the petroleum naphtha catalytic reforming is to separate by multistage cryogenic crystallization C8 aronmatic or molecular sieve simulated moving bed adsorption separation (abbreviation fractionation by adsorption) technology, and p-Xylol is separated close isomer mixture with it from boiling point.And for the processing of the dimethylbenzene of ortho position and a position, often take C
8A (C8 aronmatic) isomerization (abbreviation isomerization) technology makes it isomery and turns to p-Xylol.For increasing yield of p-xylene, utilize toluene disproportionation or toluene and carbon nine and above aromatic disproportion thereof and transalkylation (being called for short toluene disproportionation and transalkylation) reaction to generate benzene and C
8A, thereby volume increase C
8A is the operational path of effective increasing yield of p-xylene.
Up to now, in the world more typically, also the technique relevant to toluene disproportionation of comparative maturity has sixties Mo industrialized Tatoray tradition toluene disproportionation process, the MTDP of late nineteen eighties release and S-TDT technique and the TransPlus technique of releasing in recent years.Selective disproportionation of toluene is a new way of producing p-Xylol.Because toluene can carry out selective disproportionation and generate the C of benzene and high p-Xylol concentration on the ZSM-5 of modification catalyzer
8Therefore A only needs can isolate most p-Xylol through simple once the step subzero fractionation.In recent years, along with improving constantly of catalyst performance, this technique has obtained considerable progress.Its typical process has industrialized MSTDP selective disproportionation of toluene technique and the pX-Plus technique released in recent years the late nineteen eighties.
Industrialized selective disproportionation of toluene technique-MSTDP take treated ZSM-5 type mesoporous molecular sieve as the catalyst treatment methylbenzene raw material, can obtain the C of high p-Xylol concentration (85～90%, weight percent, identical except indicating below)
8The benzene of A and nitration grade.There is not yet the PX-plus technique of industrial application report, its main technique index is that under toluene conversion 30% condition, in dimethylbenzene, the selectivity of pX reaches 90%, and the mol ratio of benzene and pX (p-Xylol) is 1.37.
Yet, in the technique of this class selective disproportionation of toluene, in the harshness of the simultaneous with high para-selectivity to material choice.This type of technique can only be take toluene as raw material, and C
9 +A (carbon nine and above aromatic hydrocarbons thereof) does not have purposes in this technique, can not directly be utilized at least, causes the waste of aromatic hydrocarbon resource.In addition, this technique is a large amount of benzene of by-product also, causes the p-Xylol yield on the low side, and this is the fatal shortcoming of selective disproportionation technique.
The reactor feed of typical Tatoray technique is with toluene and C9 aromatic (C
9A) be reaction raw materials.The dimethylbenzene that is generated by Tatoray technique is to be in the isomer mixture that thermodynamic(al)equilibrium forms, and has the p-Xylol content of industrial application value generally to only have 24% left and right most.For the xylol this point of p-Xylol concentration that selective disproportionation of toluene can obtain 90% left and right, Tatoray technique is in obvious inferior position undoubtedly, but Tatoray technique is exactly that Tatoray technique can be C with respect to one of selective disproportionation of toluene technique very large advantage
9A is converted into benzene and dimethylbenzene.Document take Tatoray technique as the basis has USP4341914, Chinese patent 98110859.8, USP2795629, USP3551510, Chinese patent 97106719.8 etc.The technical process that representative USP4341914 proposes is for to carry out the aromatic hydrocarbons fractionation with reformate, the toluene that obtains and C
9A enters the Tatoray technique unit and carries out disproportionation and transalkylation reaction, and resultant of reaction is toluene and C after separating
9A and part C10 aromartic (C
10A) circulation, benzene is as the product extraction, C8 aronmatic and the C8 aronmatic from isomerization unit enter together the pX tripping device and isolate highly purified p-Xylol product, and other C8 aronmatic isomer carries out to isomerization unit the xylol that xylene isomerization reaction obtains being in thermodynamic(al)equilibrium again.
Heavy aromatics takes off alkyl production C6～C8 aromatics process and caused gradually people's attention along with the rise of selective disproportionation of toluene technique in the last few years.USP5763721 and USP5847256 have proposed respectively to be used for the catalyzer of heavy aromatics dealkylation.Wherein, USP5847256 has announced a kind of mordenite catalyst of rhenium-containing, and this catalyzer is specially adapted to transform and contains the many raw materials of ethyl, can obtain the products such as toluene, dimethylbenzene and benzene.
C
8The boiling point of each component of aromatic hydrocarbons approaches: 136.2 ℃, ethylbenzene, 138.4 ℃ of p-Xylol, 139.1 ℃ of m-xylenes, 144.4 ℃ of o-Xylols, the o-Xylol that its mid-boiling point is the highest can be separated by rectification method, need up to a hundred theoretical stages and larger reflux ratio, the ethylbenzene that boiling point is minimum also can separate by rectification method, but much more difficult.C
8The fusing point of each component of aromatic hydrocarbons has larger gap: 13.3 ℃ of p-Xylol, o-Xylol-25.2 ℃, m-xylene-47.9 ℃, ethylbenzene-94.95 ℃.Wherein the fusing point of p-Xylol is the highest, can adopt crystallization process general p-xylene separation wherein out, and is as not high in p-Xylol concentration in raw material, for reaching the acceptable yield of industrial production, generally adopts two sections crystallizations.At first USP3177255, USP3467724 crystallize out most p-Xylol under the low temperature of-80～-60 ℃ and make productive rate reach theoretical maximum, and crystal purity between 65～85%, is carrying out crystallization for the second time after fusing at this moment; Tc generally at-20～0 ℃, can obtain the p-Xylol of 99% above purity for the second time, and in mother liquor, p-Xylol content is higher, can return to crystallized region recycle for the first time.
Utilize sorbent material to C
8The difference of each compositional selecting of aromatic hydrocarbons can be by adsorption method of separation with p-xylene separation out, after this method realizes industrialization in nineteen seventies for producing the main method of p-Xylol.USP2985589 has described the method for utilizing the simulation moving-bed separating paraxylene of adverse current; USP3686342, USP3734974, CN98810104.1 have described sorbent material that fractionation by adsorption uses and have been X or the Y zeolite of barium type or barium potassium type; USP3558732, USP3686342 use respectively toluene and p-Diethylbenzene as the desorbing agent of fractionation by adsorption.
Summary of the invention
Technical problem to be solved by this invention be in conventional art when producing p-Xylol, existence is because p-Xylol concentration in xylol is low, cause dimethylbenzene separating unit and the isomerization unit internal circulating load is large, energy consumption is high problem, a kind of new p-Xylol production method is provided.The method is with benzene, toluene, C
8A and C
9 +A (carbon nine and above aromatic hydrocarbons thereof) produces p-Xylol for raw material, has the concentration that can improve p-Xylol in xylol, reduce greatly the scale of p-xylene separation unit, isomerization unit and aromatic hydrocarbons fractionation unit, thereby reduce the advantage of the energy consumption of whole device.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is as follows: a kind of combined method of producing p-Xylol comprises the following steps:
A. separate the mixing raw material that contains benzene, toluene, C8 aronmatic, carbon nine and above aromatic hydrocarbons and non-aromatics from reformer unit, isolate first strand of benzene, first strand of toluene, first burst of C8 aronmatic, carbon nine and above aromatic hydrocarbons and non-aromatics;
B.a) the isolated carbon nine of step and above aromatic hydrocarbons enters carbon nine and above aromatic hydrocarbons takes off the alkyl technique unit carries out dealkylation under hydro condition, generate second strand of benzene, second strand of toluene and second strand of C8 aronmatic;
C. first strand of toluene and second strand of toluene enter the selective disproportionation of toluene technique unit together, carry out toluene selective disproportionation reaction under hydro condition, generate C8 aronmatic and the benzene logistics that contains p-Xylol after reaction, after separating, obtain the 3rd strand of C8 aronmatic, the 3rd strand of toluene and the 3rd strand of benzene, wherein the 3rd strand of toluene turns back to the methylbenzene shape selective disproportionation technique unit;
D. first strand of C8 aronmatic, second strand of C8 aronmatic are sent into adsorption separation unit after mixing, and obtain the 5th strand of C8 aronmatic;
E. the 3rd strand of C8 aronmatic and the 5th strand of C8 aronmatic are sent into the Crystallization Separation unit, obtain the 4th strand of C8 aronmatic and pure p-Xylol, and wherein the 4th strand of C8 aronmatic turns back to adsorption separation unit.
In technique scheme, selective disproportionation of toluene unit catalyzer used is the type ZSM 5 molecular sieve catalyzer, type ZSM 5 molecular sieve contains at least a metal or its oxide compound that is selected from platinum, molybdenum or magnesium, and its consumption is 0.005～5% by weight percentage; The operational condition of selective disproportionation of toluene technique unit is as follows: reaction pressure is 1～4MPa, and temperature of reaction is 300～480 ℃, and hydrogen/hydrocarbon mol ratio is 0.5～10: 1, and the liquid weight air speed is 0.8～8 hour
-1It is at least a molecular sieve that is selected from beta-zeolite, mordenite or MCM-22 that carbon nine and above aromatic hydrocarbons thereof take off alkyl technique unit catalyzer used, and the metal of bismuth-containing or its oxide compound in catalyzer, its consumption are 0.005～5% by weight percentage; The operational condition that carbon nine and above aromatic hydrocarbons thereof take off the alkyl technique unit is as follows: reaction pressure is 1～5MPa, and temperature of reaction is 250～480 ℃, and hydrogen/hydrocarbon mol ratio is 0.5～8: 1, and weight space velocity is 0.8～10 hour
-1The p-xylene separation unit adopts absorption-Crystallization Separation combination process separating paraxylene, and Crystallization Separation adopts film-falling crystallization to separate or suspension crystallization separates; The Tc that film-falling crystallization separates is-30～5 ℃; The Tc that suspension crystallization separates is-30～5 ℃, and washings/crystallization weight ratio is 0.05～0.5: 1.
In the present invention, take off the alkyl technique unit at carbon nine and above aromatic hydrocarbons thereof, under hydro condition, catalyzer has and carbon nine and above aromatic hydrocarbons thereof are taken off alkyl becomes benzene, toluene and C
8The function of A.Carbon nine and above aromatic hydrocarbons thereof take off toluene that the alkyl technique unit generates and enter the selective disproportionation of toluene unit; The benzene that reaction generates does not have the benzene of unnecessary extraction at this unit internal recycle, can reduce like this generation of by-product benzene as far as possible; The C that reaction generates
8A enters fractionation by adsorption and isomerization unit is produced the xylol of p-Xylol concentration 80～95%.Carbon nine and above aromatic hydrocarbons thereof take off toluene that the alkyl technique unit generates and enter the selective disproportionation of toluene unit together with other toluene in Aromatic Hydrocarbon United Plant, under the effect of platiniferous ZSM-5 catalyzer, toluene selective disproportionation reaction occurs, generate benzene and the xylol that contains the high density p-Xylol, p-Xylol concentration can reach 80～95%, the Mixed XYLENE that this xylol and fractionation by adsorption obtain is sent to the Crystallization Separation unit and obtains pure p-Xylol, and the residue xylol also enters fractionation by adsorption and isomerization unit is produced pure p-Xylol.In the present invention, p-xylene separation adopts absorption-crystallization combination separation scheme, fractionation by adsorption does not need to obtain pure p-Xylol, only need obtain the xylol of p-Xylol concentration 80～95%, in adsorption separation unit, the sorbent material consumption reduces greatly thereby make, and adsorption separation device is simplified greatly.Can find out, such operational path can allow the concentration of producing p-Xylol in the xylol that obtains significantly improve, and takes full advantage of again C
9 +The A resource greatly reduces the treatment scale of isomerization unit and adsorption separation unit, has effectively reduced energy consumption and facility investment scale, and has reduced production cost, has obtained technique effect preferably.
Description of drawings
Fig. 1 is the technical process of traditional p-Xylol production equipment.
Fig. 2 is the combination process flow process that the present invention produces p-Xylol.
In Fig. 1 or Fig. 2, I is the reformer unit deheptanizer; II is the Aromatics Extractive Project unit; III is the benzene toluene separating unit after extracting; IV is the benzenol hydrorefining unit; VI is the selective disproportionation technique unit; VII is that heavy aromatics takes off the alkyl technique unit; VIII is the xylene isomerization process unit; IX is adsorption separation unit; X is the aromatic hydrocarbons fractionation unit of selective disproportionation; XI is the Crystallization Separation unit.1 is the reformation de-pentane oil, and 2 is the C that distillates from the deheptanizer tower top
7 -(comprising that benzene, toluene and carbon six carbon seven are non-aromatic), 3 carbon eight and above arene streams for the extraction of deheptanizer tower reactor, 4 for extracting benzene and the toluene logistics after non-aromatic, 5 is non-aromatic, 6 is the high purity product benzene that the benzene column overhead after extracting is extracted, 7 is the toluene that the toluene tower tower top after extracting is extracted, 8 C for the extraction of the toluene tower reactor after extracting
8 +A (carbon eight and above aromatic hydrocarbons thereof), 9 is disproportionation and transalkylation product stream, 10 C for the extraction of heavy aromatics column overhead
9A and part C
10A, 11 is the xylol of extracting out from the benzenol hydrorefining tower top, 12 is the C that heavy aromatics tower tower reactor is extracted out
10A, 13 for heavy aromatics takes off the still liquid that alkyl unit benzene tower tower reactor is extracted out, 14 a small amount of toluene of separating for adsorption separation unit, 15 C that contain the high density p-Xylol that separate for adsorption separation unit
8 +A, 16 for fractionation by adsorption goes out xylol after PX, and 17 is the C that isomerization unit deheptanizer tower reactor is discharged
8 +The A logistics, 18 logistics that contain benzene and toluene of extracting for isomerization unit deheptanizer tower top, 19 is the benzene logistics of disproportionation and transalkylation extraction, the 20 nitrated benzene of extracting for the benzene column overhead of selective disproportionation, 21 toluene of extracting for the toluene tower tower top of selective disproportionation, 22 C that extract for the benzenol hydrorefining tower top of selective disproportionation
8 +A, 23 is the still liquid that the benzenol hydrorefining tower reactor of selective disproportionation is extracted out, the 24 pure p-Xylol of separating for the Crystallization Separation unit, 25 go out xylol after PX for Crystallization Separation.
The technical process of tradition p-Xylol production equipment as shown in Figure 1.Enter deheptanizer I from reformation depentanizer tower bottoms 1, tower top is told carbon seven and following aromatic hydrocarbons non-aromatics logistics 2 thereof and is entered Aromatics Extractive Project unit II and carry out separating of aromatic hydrocarbons and non-aromatics, isolated non-aromatic 5 discharge, unit III is removed in benzene toluene logistics 4, the benzene column overhead of products benzene 6 after the extracting sent, and the toluene tower tower reactor of xylol 8 after the extracting extracted out and entered benzenol hydrorefining unit IV.In addition, deheptanizer tower reactor logistics 3 also enters benzenol hydrorefining unit VI, mix carbon eight logistics 11 and distillate p-xylene separation unit IX from tower top, C9 aromatic 10 and from the raw material of the isolated toluene logistics 7 of toluene tower tower top as toluene disproportionation and transalkylation II, C
10 +A logistics 12 is sent as byproduct; Disproportionation directly enters unit III with 9 of transalkylation product streams and separates; Adsorption separation unit IX isolates purpose product p-Xylol 15, and a small amount of toluene 14 returns to toluene disproportionation unit VI, and other xylol 16 enters xylene isomerization unit VIII and carries out isomerization reaction, the C that isomerization unit deheptanizer tower reactor is discharged
8 +A logistics 17 is sent to benzenol hydrorefining unit IV, and the logistics that contains benzene and toluene 18 that the deheptanizer tower top is extracted is sent to the catalytic reforming unit.
Produce the combination process flow process of p-Xylol in the present invention as shown in Figure 2.Be that with the improvements of traditional technology technique of the present invention changes the toluene disproportionation process unit in traditional technology into C9 aromatic and takes off the alkyl technique unit, in addition, increased by a cover selective disproportionation of toluene unit VI.The place that Fig. 2 is identical with Fig. 1 is no longer narrated, and the below only elaborates with regard to difference.In technique of the present invention, former carbon nine and the above virtue thereof that is used as toluene disproportionation and transalkylation raw material taken off the raw material of alkyl unit through 10 as heavy aromatics, the benzene that reaction generates is at unit internal recycle, C
7 +Toluene tower in the benzene toluene tower unit of A (carbon seven and above aromatic hydrocarbons thereof) logistics 13 after the extracting separates, the xylol 11 of dimethylbenzene fractionation unit extraction enters adsorption separation unit and separates the C that obtains containing the high density p-Xylol all as the raw material of selective disproportionation unit in toluene logistics 7 (comprise the toluene of bringing in raw material and react the toluene that generates)
8 +Al5, selective disproportionation unit product logistics 9 enters the aromatic hydrocarbons fractionation unit X of selective disproportionation, from the nitrated benzene 20 of benzene column overhead extraction, toluene tower overhead extraction toluene 21 turns back to selective disproportionation unit VI, the still liquid 23 that the benzenol hydrorefining tower reactor is extracted out is sent into benzenol hydrorefining unit III, dimethylbenzene tower top extraction C
8 +A logistics 22, Crystallization Separation unit XI is sent in logistics 22 and logistics 15, isolates pure p-Xylol 24, and other xylol 25 is delivered to adsorption separation unit IX.
The present invention is further illustrated below by specific embodiment, and still, scope of the present invention has more than and is limited to the scope that embodiment covers.
Embodiment
[embodiment 1]
The mixing raw material that will contain benzene, toluene, C8 aronmatic, carbon nine and above aromatic hydrocarbons thereof and non-aromatics separates, obtain carbon nine and above aromatic hydrocarbons thereof, as raw material, under hydro condition, carry out carbon nine and above aromatic hydrocarbons dealkylation Performance thereof in fixed-bed reactor.Reactor inside diameter
Millimeter, 1000 millimeters of length, stainless steel.Beds is all fillings up and down
The millimeter granulated glass sphere plays air-flow and distributes and supporting role, and in reactor, filling 20 gram bismuth-containings are 0.05% beta-zeolite catalyzer.Aroamtic hydrocarbon raw material with after hydrogen mixes from top to bottom by beds, carry out C
9 +The dealkylation of A generates benzene, toluene and C
8A, temperature of reaction is 425 ℃, and pressure is 3.0MPa, and weight space velocity is 2.0 hours
-1, hydrogen/hydrocarbon mol ratio is 5.0: 1.
C in raw material
9 +A derives from petrochemical complex Aromatic Hydrocarbon United Plant, H
2Be electrolysis hydrogen, through dehydrating processing, reaction result is listed in table 1.
Table 1 C9 aromatic dealkylation raw material and product composition analysis
| Component | NA | Ben | Tol | C 8A | C 9 +A | C 10 +A | ∑ |
| Raw material, % by weight | 0.00 | 0.00 | 0.01 | 0.82 | 93.24 | 5.93 | 100.00 |
| Product, % by weight | 6.13 | 1.92 | 11.89 | 19.22 | 57.82 | 3.02 | 100.00 |
Wherein: NA is non-aromatics, C
10 +A is carbon ten and above aromatic hydrocarbons thereof, and Ben is benzene, and Tol is toluene.
Can find out from embodiment 1: raw material C
9 +A has produced benzene, toluene and C after reaction
8A。
The mixing raw material that will contain benzene, toluene, C8 aronmatic, carbon nine and above aromatic hydrocarbons thereof and non-aromatics separates, and obtains toluene, take toluene as raw material, under hydro condition, carries out toluene selective disproportionation reaction on fixed-bed reactor.Reactor inside diameter
Millimeter, 1000 millimeters of length, stainless steel.Beds is all fillings up and down
The millimeter granulated glass sphere plays air-flow and distributes and supporting role, and in reactor, filling 20 grams contain 0.05% platinum ZSM-5 molecular sieve catalyzer.Toluene with after hydrogen mixes from top to bottom by beds, carry out toluene selective disproportionation reaction, generate the C of benzene and high p-Xylol concentration
8A。
Raw material toluene derives from petrochemical complex Aromatic Hydrocarbon United Plant, H
2Be electrolysis hydrogen, through dehydrating processing, temperature of reaction is 420 ℃, and reaction pressure is 1.5MPa, and air speed is 4.0 hours
-1, hydrogen/hydrocarbon mol ratio is 3.0: 1.Reaction result is as shown in table 2.
Table 2 toluene selective disproportionation reaction result
| Component | NA | Ben | Tol | PX | C 8A* | C 9 +A | ∑ |
| Form % by weight | 1.74 | 14.05 | 69.95 | 11.62 | 2.02 | 0.62 | 100.00 |
Annotate: C
8A* refers to other C8 aronmatic except PX, and is as follows.
The aromatic hydrocarbons fractionation unit of toluene selective disproportionation reaction product through selective disproportionation separated, obtain xylol, as raw material, carry out Crystallization Separation in falling-film crystallizer.The falling-film crystallizer internal diameter
Millimeter, external diameter
Millimeter, 500 millimeters of length, stainless steel.The crystallizer Raw is walked tube side.Raw material and cryogen countercurrent flow in crystallizer carries out Crystallization Separation, obtains mother liquor, sweating and pure p-Xylol.
In Crystallizing process, be divided into three steps and carry out: material flow is 5 ml/min, and feeding temperature is 25 ℃, the cryogen flow is 50 ml/min, and refrigerant temperature is-20 ℃, and p-Xylol is in the crystallization of crystallizer tube wall, residue is mother liquor, and the raw material charging stopped charging after 2 hours; Refrigerant temperature is brought up to 20 ℃, plays heat effect, and purpose is melted the part crystal, and melting liquid is called sweating; Change product-collecting into after 15 minutes, refrigerant temperature is brought up to 30 ℃, melts whole crystal, obtains pure p-Xylol.What film-falling crystallization separated the results are shown in Table 3.
The result that table 3 film-falling crystallization separates
| Component | Raw material, % by weight | Sweating, % by weight | Mother liquor, % by weight | Product, % by weight |
| PX | 85.15 | 96.73 | 42.51 | 99.84 |
| C 8A* | 14.85 | 3.27 | 57.49 | 0.16 |
[embodiment 2]
Reaction process such as embodiment 1.The aromatic hydrocarbons fractionation unit of toluene selective disproportionation reaction product through selective disproportionation separated, obtain xylol, as raw material, carry out suspension crystallization and separate.The volume of suspension crystallization device is 500 liters, and with chuck and agitator, stainless steel, the volume of washing tower are 40 liters, stainless steel.Raw material carries out suspension crystallization in crystallization, the slurry after crystallization enters and carries out solid-liquid separation and purifying products in washing tower.
The suspension crystallization sepn process comprises suspension crystallization and washing purge process, and the material flow of suspension crystallization is 200 liter/mins of clocks, and material temperature is 20 ℃, and Tc is-5 ℃, and the washings flow of washing purifying is 15 liter/mins of clocks, and wash temperature is 20 ℃.What suspension crystallization separated the results are shown in Table 4.
The result that table 4 suspension crystallization separates
| Component | Raw material, % by weight | Mother liquor, % by weight | Product, % by weight |
| PX | 85.15 | 63.37 | 99.84 |
| C 8A* | 14.85 | 36.63 | 0.16 |
[embodiment 3]
With C in typical reformation de-pentane oil
6A～C
10 +Each material of hydrocarbon consist of basic data, investigate the present invention and produce p-Xylol and the ability of benzene and the treatment scale situation of each unit according to the technical process shown in accompanying drawing 2.Typical reformer is sent the composition distribution of aromatic hydrocarbons and the flow rate of each component that the present embodiment adopts sees Table 5.
Table 5 reformation de-pentane oil aromatic hydrocarbons forms and flow rate
| Form | Ben | Tol | C 8A | C 9A | C 10 + | ∑ |
| Form % by weight | 14.41 | 26.79 | 33.53 | 24.02 | 1.25 | 100.00 |
| Flow, kg/hr | 12673 | 23560 | 29482 | 21122 | 1095 | 87932 |
C wherein
10 +Be carbon ten and above aromatic hydrocarbons thereof.
According to the aromatic hydrocarbons flow rate (fresh feed) in the described technical process of the present invention of accompanying drawing 2 and table 5 and embodiment 1 carbon nine and above aromatic hydrocarbons dealkylation result, toluene selective disproportionation reaction result and film-falling crystallization separating resulting, selective disproportionation of toluene unit, heavy aromatics take off material feeding and the discharging data of alkyl unit and isomerization unit and list in table 6.The treatment scale of p-Xylol production equipment unit sees Table 7, and the output of product p-Xylol and benzene sees Table 8.
Result shows, uses the technology of the present invention, and with the listed aroamtic hydrocarbon raw material of table 5, the ultimate production that technique of the present invention can be produced p-Xylol and benzene is 78328 kg/hrs.The treatment scale of xylene isomerization unit and dimethylbenzene fractionation unit has descended respectively 26% and 27%, adsorption separation unit not only treatment scale descends to some extent, the more important thing is that the p-Xylol weight purity after fractionation by adsorption drops to 90% by original 99.9%, this has obviously reduced the design scale of device.Plant energy consumption is 18605 * 10
6Joule/ton (p-Xylol+benzene), with respect to 26579 * 10 of comparative example 1
6Joule/ton (p-Xylol+benzene), Energy Intensity Reduction 30%.Therefore, the problem such as when patent of the present invention has overcome the production p-Xylol that exists in the conventional art, xylol concentration is low, internal circulating load is large, energy consumption is high provides a kind of brand-new more economical method for the production of p-Xylol.
Table 6 embodiment 3 process stream tables
Table 7 embodiment 3 each cell processing scale tables
Table 8 embodiment 3 product productions and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 49258 | 29066 | 78328 |
| Purity, % | 99.84 | 99.94 | ? |
[embodiment 4]
The processing condition that reaction process flow process, reaction process condition, catalyzer and the suspension crystallization of employing embodiment 2 separates, consist of benchmark with the raw material shown in table 5, the xylol logistics of the reaction product of selective disproportionation of toluene unit after the aromatic hydrocarbons fractionation unit separates enters the suspension crystallization separating unit and reclaims dimethylbenzene.The treatment scale of each unit of p-Xylol production equipment sees Table 9, and the output of product p-Xylol and benzene sees Table 10.
Table 9 embodiment 4 each cell processing scale tables
Table 10 embodiment 4 product productions and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 49273 | 29067 | 78340 |
| Purity, % by weight | 99.84 | 99.94 | ? |
Result shows, uses the technology of the present invention, and with the listed aroamtic hydrocarbon raw material of table 5, the ultimate production that technique of the present invention can be produced p-Xylol and benzene is 78340 kg/hrs.The treatment scale of xylene isomerization unit and dimethylbenzene fractionation unit has descended respectively 26% and 24%, adsorption separation unit not only treatment scale descends to some extent, the more important thing is that the p-Xylol weight purity after fractionation by adsorption drops to 90% by original 99.9%, has obviously reduced the design scale of device.Plant energy consumption is 19402 * 10
6Joule/ton (p-Xylol+benzene), with respect to 26579 * 10 of comparative example 1
6Joule/ton (p-Xylol+benzene), Energy Intensity Reduction 27%.
[comparative example 1]
Still with typical reformation de-pentane oil C in table 5
6A～C
10 +The flow rate of A logistics is basic data, investigates the ability that Aromatic Hydrocarbon United Plant that as shown in Figure 1 traditional contain toluene disproportionation and alkyl transfering process unit is produced p-Xylol and benzene.The material feeding of its disproportionation and transalkylation, isomerization unit and extraction situation see Table 11, and the treatment scale of each unit sees Table 12, and the output of product p-Xylol and benzene sees Table 13.
Table 11 comparative example 1 process stream table
Table 12 comparative example 1 each cell processing scale table
Table 13 comparative example 1 product production and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 54316 | 22751 | 77067 |
| Purity, % | 99.80 | 99.94 | ? |
Result shows, traditional aromatic hydrocarbons production technique reaction aroamtic hydrocarbon raw material as listed in table 5, and the total amount of having produced altogether p-Xylol and benzene is 77067 kg/hrs, plant energy consumption is 26579 * 10
6Kilojoule/ton (p-Xylol+benzene).
Claims (5)
1. combined method of producing p-Xylol comprises the following steps:
A. separate the mixing raw material that contains benzene, toluene, C8 aronmatic, carbon nine and above aromatic hydrocarbons and non-aromatics from reformer unit, isolate first strand of benzene, first strand of toluene, first burst of C8 aronmatic, carbon nine and above aromatic hydrocarbons and non-aromatics;
B.A) the isolated carbon nine of step and above aromatic hydrocarbons enters carbon nine and above aromatic hydrocarbons takes off the alkyl technique unit carries out dealkylation under hydro condition, generate second strand of benzene, second strand of toluene and second strand of C8 aronmatic;
C. first strand of toluene and second strand of toluene enter the selective disproportionation of toluene technique unit together, carry out toluene selective disproportionation reaction under hydro condition, generate C8 aronmatic and the benzene logistics that contains p-Xylol after reaction, after separating, obtain the 3rd strand of C8 aronmatic, the 3rd strand of toluene and the 3rd strand of benzene, wherein the 3rd strand of toluene turns back to the methylbenzene shape selective disproportionation technique unit;
D. send into adsorption separation unit after first strand of C8 aronmatic and second strand of C8 aronmatic mix, obtain the 5th strand of C8 aronmatic;
E. the 3rd strand of C8 aronmatic and the 5th strand of C8 aronmatic are sent into the Crystallization Separation unit, obtain the 4th strand of C8 aronmatic and pure p-Xylol, and wherein the 4th strand of C8 aronmatic turns back to adsorption separation unit;
Described p-xylene separation unit adopts absorption-Crystallization Separation combination process separating paraxylene, and Crystallization Separation adopts film-falling crystallization to separate or suspension crystallization separates, and the Tc that film-falling crystallization separates is-30～5 ℃; The Tc that suspension crystallization separates is-30～5 ℃, and washings/crystal weight ratio is 0.05～0.5: 1.
2. produce according to claim 1 the combined method of p-Xylol, it is characterized in that selective disproportionation of toluene unit catalyzer used is the type ZSM 5 molecular sieve catalyzer, type ZSM 5 molecular sieve contains at least a metal or its oxide compound that is selected from platinum, molybdenum or magnesium, and its consumption is 0.005～5% by weight percentage.
3. produce according to claim 1 the combined method of p-Xylol, the operational condition that it is characterized in that the selective disproportionation of toluene technique unit is as follows: reaction pressure is 1～4MPa, temperature of reaction is 300～480 ℃, and hydrogen/hydrocarbon mol ratio is 0.5～10: 1, and the liquid weight air speed is 0.8～8 hour
-1
4. produce according to claim 1 the combined method of p-Xylol, it is characterized in that it is at least a molecular sieve that is selected from beta-zeolite, mordenite or MCM-22 that carbon nine and above aromatic hydrocarbons thereof take off alkyl technique unit catalyzer used, the metal of bismuth-containing or its oxide compound in catalyzer, its consumption are 0.005～5% by weight percentage.
5. produce according to claim 1 the combined method of p-Xylol, it is characterized in that carbon nine and above aromatic hydrocarbons thereof take off the operational condition of alkyl technique unit as follows: reaction pressure is 1～5MPa, temperature of reaction is 250～480 ℃, hydrogen/hydrocarbon mol ratio is 0.5～8: 1, and weight space velocity is 0.8～10 hour
-1
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