CN101811927B - Method for producing paraxylene - Google Patents
Method for producing paraxylene Download PDFInfo
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- CN101811927B CN101811927B CN2009100568964A CN200910056896A CN101811927B CN 101811927 B CN101811927 B CN 101811927B CN 2009100568964 A CN2009100568964 A CN 2009100568964A CN 200910056896 A CN200910056896 A CN 200910056896A CN 101811927 B CN101811927 B CN 101811927B
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Abstract
The invention relates to a method for producing paraxylene, which manly solves the problems of low concentration of paraxylene in mixed xylene during paraxylene production, large circulating load of aromatic hydrocarbon treatment, strict requirements for raw reaction materials, high energy consumption and the like existing in the prior art. The method comprises the following steps of: separating mixed raw materials from a reforming unit; introducing separated C9 and heavier aromatic hydrocarbons into a C9 and heavier aromatic hydrocarbon dealkylation processing unit for a dealkylation reaction to produce a second part of benzene, a second part of methylbenzene and a second part of C8 aromatic hydrocarbon; introducing methylbenzene into a methylbenzene selective disproportionation processing unit for a selective disproportionation reaction of methylbenzene to produce a C8 aromatic hydrocarbon and benzene flow including paraxylene so as to obtain a third part of C8 aromatic hydrocarbon, a third part of methylbenzene and a third part of benzene; after mixing the low-concentration C8 aromatic hydrocarbon, introducing the mixture into a crystallization and separation unit to obtain C8 aromatic hydrocarbon including paraxylene with high concentration; and introducing the C8 aromatic hydrocarbon including paraxylene with high concentration into an absorption and separation unit to obtain the product of paraxylene. With the technical scheme, the invention well solves the problems and can be applied to the industrial production of paraxylene.
Description
Technical field
The present invention relates to the method that a kind of p-Xylol is produced.
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 widely purposes is 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 or molecular sieve simulated moving bed adsorption separation (abbreviation fractionation by adsorption) technology by multistage cryogenic crystallization the C8 aronmatic, and p-Xylol is separated the 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 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 with 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 is at the C that can carry out selective disproportionation generation 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 the selectivity of pX reaches 90% in the dimethylbenzene under toluene conversion 30% condition, and the mol ratio of benzene and pX 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 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 as reaction raw materials take toluene and C9 aromatic (C9A).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 about 24% most.For the xylol this point that selective disproportionation of toluene can obtain the p-Xylol concentration about 90%, Tatoray technique is in obvious inferior position undoubtedly, but Tatoray technique is exactly that Tatoray technique can be converted into benzene and dimethylbenzene to C9A with respect to one of selective disproportionation of toluene technique very large advantage.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 a heatable brick bed group-transfer reaction, and resultant of reaction is toluene and C after separating
9A and part carbon ten (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 the xylol that xylene isomerization reaction obtains being in thermodynamic(al)equilibrium again to isomerization unit.
Heavy aromatics takes off alkyl and produces C
6～C
8Aromatics process caused people's attention gradually 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 ℃ in 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 not high such as p-Xylol concentration in the raw material, for reaching the acceptable yield of industrial production, generally adopts two sections crystallizations.USP3177255, USP3467724 at first crystallize out most p-Xylol under-80～-60 ℃ low temperature and make productive rate reach theoretical maximum, this moment crystal purity between 65～85%, is carrying out the crystallization second time after the fusing; Tc can obtain the p-Xylol of 99% above purity generally at-20～0 ℃ for the second time, and p-Xylol content is higher in the mother liquor, can return for the first time crystallized region recycle.
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 the conventional art when producing p-Xylol, exist owing to p-Xylol concentration in the xylol is low, the problem such as cause the dimethylbenzene separating unit and the isomerization unit internal circulating load is large, energy consumption is high provides a kind of new p-Xylol production method.The method is with benzene, toluene, C
8A and C
9 +A is that raw material is produced p-Xylol, improves the concentration of p-Xylol in the xylol, reduces greatly the scale of p-xylene separation unit, isomerization unit and aromatic hydrocarbons fractionation unit, thereby reduces 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: the method that a kind of p-Xylol is produced may further comprise the 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, under hydro condition, carry out toluene selective disproportionation reaction, generate C8 aronmatic and the benzene logistics that contains p-Xylol after the 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 selective disproportionation of toluene technique unit;
D. send into adsorption separation unit after first strand of C8 aronmatic, second strand of C8 aronmatic and the 3rd strand of C8 aronmatic mix, obtain containing the C8 aronmatic of high density p-Xylol;
E. the C8 aronmatic that contains the high density p-Xylol is sent into the Crystallization Separation unit, obtains the p-Xylol product, and the 4th strand of C8 aronmatic, and the 4th strand of C8 aronmatic turns back to adsorption separation unit.
In technique scheme, the used catalyzer in selective disproportionation of toluene unit 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 the 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, and the liquid weight air speed is 0.8～8 hour
-1It is at least a molecular sieve that is selected among beta-zeolite, mordenite or the MCM-22 that carbon nine and above aromatic hydrocarbons thereof take off the used catalyzer of alkyl technique unit, and the metal of bismuth-containing or its oxide compound in the 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, and weight space velocity is 0.8～10 hour
-1The p-xylene separation unit adopts fractionation by adsorption and the Crystallization Separation separating paraxylene that combines, and Crystallization Separation can adopt 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-15～5 ℃, and washings/crystal weight ratio is 0.05～0.5.The weight concentration of p-Xylol is 75～95% in the C8 aronmatic of high density p-Xylol; The weight concentration of p-Xylol is 〉=99.8% in the p-Xylol product.
Among 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.The toluene that carbon nine and above aromatic hydrocarbons thereof take off the generation of alkyl technique unit enters 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.Toluene other toluene in Aromatic Hydrocarbon United Plant that carbon nine and above aromatic hydrocarbons thereof take off the generation of alkyl technique unit enters the selective disproportionation of toluene unit, 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%, this xylol and carbon nine and above aromatic hydrocarbons thereof take off C8 aronmatic that the alkyl technique unit generates and are sent to absorption-Crystallization Separation assembled unit and obtain the p-Xylol product, and wherein to obtain p-Xylol concentration be that 80～90% xylol is sent into Crystallization Separation and purified to fractionation by adsorption.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 has reduced 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 preferably technique effect.
Description of drawings
Fig. 1 is the technical process of traditional p-Xylol production equipment.
Fig. 2 is the technical process that p-Xylol of the present invention is produced.
I is the reformer unit deheptanizer among Fig. 1 or Fig. 2; II is the Aromatics Extractive Project unit; III is the benzene toluene separating unit after the extracting; IV is the benzenol hydrorefining unit; V is toluene disproportionation and alkyl transfering process 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 Crystallization Separation unit.1 is the reformation de-pentane oil, and 2 is the C that distillates from the deheptanizer cat head
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 the extracting is extracted, 7 is the toluene that the toluene tower cat head after the extracting is extracted, 8 C for the extraction of the toluene tower reactor after the extracting
8 +A, 9 is disproportionation and transalkylation product stream, 10 is C
8 +The C that heavy aromatics column overhead in the A fractionation unit is extracted out
9A and part C
10A, 11 is the xylol of extracting out from the benzenol hydrorefining cat head, 12 is the C that heavy aromatics tower tower reactor is extracted out
10A, 13 take off alkyl unit benzene tower tower reactor still liquid for heavy aromatics, 14 a small amount of toluene of separating for adsorption separation unit, 15 C8 aronmatics that contain the high density p-Xylol of separating for adsorption separation unit, 16 for fractionation by adsorption goes out xylol behind the 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 cat head, 19 is the benzene logistics of disproportionation and transalkylation extraction, the 20 nitrated benzene of extracting for the benzene column overhead of selective disproportionation, the 21 p-Xylol products of separating for the Crystallization Separation unit, 22 for Crystallization Separation goes out C8 aronmatic behind the PX, and 23 is adsorption separation unit high density p-Xylol out.
The technical process of tradition p-Xylol production equipment as shown in Figure 1.Enter deheptanizer I from reformation depentanizer tower bottoms 1, cat head 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 IV, mix carbon eight logistics 11 and distillate p-xylene separation unit IX from cat head, C9 aromatic 10 and from the raw material of the isolated toluene logistics 7 of toluene tower cat head 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 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 cat head is extracted is sent to the catalytic reforming unit.
The technical process that p-Xylol of the present invention is produced 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 the traditional technology into C9 aromatic and takes off the alkyl technique unit, in addition, increased by cover selective disproportionation of toluene unit VI and a Crystallization Separation unit X.The place that Fig. 2 is identical with Fig. 1 is no longer narrated, and the below only elaborates with regard to difference.In the technique of the present invention former carbon nine and the above aromatic hydrocarbons 10 thereof that is used as toluene disproportionation and transalkylation raw material is taken off the raw material of alkyl unit 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 logistics 13 after the extracting separates, toluene logistics 7 (comprising the toluene that the toluene brought in the raw material and reaction generate) is all as the raw material of selective disproportionation unit, the selective disproportionation unit obtains nitrated benzene 20 and product stream 9, product stream 9 is sent into the benzene toluene unit after the extracting, the logistics 8 of isolating behind benzene and the toluene is sent into benzenol hydrorefining unit IV, dimethylbenzene cat head extraction C
8 +A logistics 11, logistics 11 is sent into adsorption separation unit and is isolated high density p-Xylol 23, and high density p-Xylol 23 is sent into Crystallization Separation unit X, isolates pure p-Xylol 21, and other xylol 22 turns back 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]
By flow process shown in Figure 2, with C in the typical reformation de-pentane oil
6A～C
10 +Each material of hydrocarbon consist of basic data, investigate the present invention and produce the ability of p-Xylol and benzene and the treatment scale situation of each unit.Typical reformer is sent the composition distribution of aromatic hydrocarbons and the flow rate of each component that the present embodiment adopts sees Table 1.
Carbon nine and above aromatic hydrocarbons thereof take off the alkyl technique unit and adopt fixed-bed reactor, and the filling bismuth-containing is 0.05% beta-zeolite catalyzer in the reactor, and reaction conditions is: 385 ℃ of temperature of reaction, pressure are 3.0MPa, and weight space velocity is 2.0 hours
-1, hydrogen/hydrocarbon mol ratio is 3.0.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.
The selective disproportionation of toluene technique unit adopts fixed-bed reactor, and filling contains 0.05% platinum ZSM-5 molecular sieve catalyzer in the reactor, and reaction conditions is: 385 ℃ of temperature of reaction, pressure are 3.0MPa, and weight space velocity is 2.0 hours
-1, hydrogen/hydrocarbon mol ratio is 3.0.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.
6 grades of adsorption separation unit employings are simulation moving-bed, filling sorbent material in the moving-bed, and the fractionation by adsorption service temperature is 130 ℃.
The Crystallization Separation unit adopts film-falling crystallization to separate, and Crystallization Separation is divided crystallization, sweating and three steps of melting, and wherein Tc is-20 ℃, and sweating temperature is 15 ℃, and melt temperature is 30 ℃.
Table 1 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 |
Wherein: NA is non-aromatics, and Ben is benzene, and Tol is toluene, C
8A is C8 aronmatic, C
9A is C9 aromatic, C
10 +A is carbon ten and above aromatic hydrocarbons thereof, below identical.
Operate according to the parameter that provides in accompanying drawing 2 described technical process of the present invention and the example, 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 2.The treatment scale of p-Xylol production equipment unit sees Table 3, and the output of product p-Xylol and benzene sees Table 4.
Table 2 embodiment 1 process stream table
Annotate: C
8A
*Refer to other C8 aronmatic except PX, as follows.
Table 3 embodiment 1 each cell processing scale table
| The unit title | Heavy aromatics takes off alkyl unit | Isomerization unit | Adsorption separation unit | The Crystallization Separation unit | The dimethylbenzene fractionation unit |
| Scale, kg/hr | 38750 | 161209 | 201057 | 54731 | 235861 |
Table 4 embodiment 1 product production and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 49258 | 29066 | 78328 |
| Purity, % | 99.80 | 99.94 |
The result shows, uses the technology of the present invention, and with the listed aroamtic hydrocarbon raw material of table 1, the ultimate production that technique of the present invention can be produced p-Xylol and benzene is 78324 kg/hrs.The treatment scale of xylene isomerization unit, adsorption separation unit and dimethylbenzene fractionation unit has descended respectively 26%, 27% and 27%, and this has obviously reduced the design scale of device.Plant energy consumption is 21000 * 10
6Joule/ton (p-Xylol+benzene), with respect to 26579 * 10 of Comparative Examples
6Joule/ton (p-Xylol+benzene), Energy Intensity Reduction 21%.Therefore, the problem such as xylol concentration was low when patent of the present invention had overcome the production p-Xylol that exists in the conventional art, internal circulating load is large, energy consumption is high provides a kind of brand-new more economical method for the production of p-Xylol.
[embodiment 2]
By flow process shown in Figure 2, with C in the typical reformation de-pentane oil
6A～C
10 +Each material of hydrocarbon consist of basic data, investigate the present invention and produce the ability of p-Xylol and benzene and the treatment scale situation of each unit.Typical reformer is sent the composition distribution of aromatic hydrocarbons and the flow rate of each component that the present embodiment adopts sees Table 1.
Carbon nine and above aromatic hydrocarbons thereof take off the alkyl technique unit and adopt fixed-bed reactor, the h-mordenite of filling bismuth-containing 0.10% in the reactor, and reaction conditions is: 320 ℃ of temperature of reaction, pressure are 1.0MPa, weight space velocity is 0.8 hour
-1, hydrogen/hydrocarbon mol ratio is 2.0.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.
The selective disproportionation of toluene technique unit adopts fixed-bed reactor, and filling contains 0.3% molybdenum and 0.8% magnesium ZSM-5 molecular sieve catalyzer in the reactor, and reaction conditions is: 320 ℃ of temperature of reaction, pressure are 1.0MPa, and weight space velocity is 0.8 hour
-1, hydrogen/hydrocarbon mol ratio is 1.0.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.
3 grades of adsorption separation unit employings are simulation moving-bed, filling sorbent material in the moving-bed, and the fractionation by adsorption service temperature is 130 ℃.
The Crystallization Separation unit adopts suspension crystallization to separate, and Tc is 5 ℃.
Operate according to the parameter that provides in accompanying drawing 2 described technical process of the present invention and the example, the treatment scale of p-Xylol production equipment unit sees Table 5, and the output of product p-Xylol and benzene sees Table 6.
Table 5 embodiment 2 each cell processing scale table
| The unit title | Heavy aromatics takes off alkyl unit | Isomerization unit | Adsorption separation unit | The Crystallization Separation unit | The dimethylbenzene fractionation unit |
| Scale, kg/hr | 38750 | 161532 | 203754 | 54731 | 245876 |
Table 6 embodiment 2 product productions and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 49273 | 29067 | 78340 |
| Purity, % by weight | 99.80 | 99.94 |
The result shows, uses the technology of the present invention, and with the listed aroamtic hydrocarbon raw material of table 1, 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, adsorption separation unit and dimethylbenzene fractionation unit has descended respectively 26%, 26% and 24%, has obviously reduced the design scale of device.Plant energy consumption is 21530 * 10
6Joule/ton (p-Xylol+benzene), with respect to 26579 * 10 of Comparative Examples
6Joule/ton (p-Xylol+benzene), Energy Intensity Reduction 19%.
[embodiment 3]
By flow process shown in Figure 2, with C in the typical reformation de-pentane oil
6A～C
10 +Each material of hydrocarbon consist of basic data, investigate the present invention and produce the ability of p-Xylol and benzene and the treatment scale situation of each unit.Typical reformer is sent the composition distribution of aromatic hydrocarbons and the flow rate of each component that the present embodiment adopts sees Table 1.
Carbon nine and above aromatic hydrocarbons thereof take off the alkyl technique unit and adopt fixed-bed reactor, the Hydrogen MCM-22 zeolite catalyst of filling bismuth-containing 0.30% in the reactor, and reaction conditions is: 460 ℃ of temperature of reaction, pressure are 41.0MPa, weight space velocity is 3.0 hours
-1, hydrogen/hydrocarbon mol ratio is 8.0.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.
The selective disproportionation of toluene technique unit adopts fixed-bed reactor, filling platiniferous 0.2% and 0.5% magnesium ZSM-5 molecular sieve catalyzer in the reactor, and reaction conditions is: 450 ℃ of temperature of reaction, pressure are 6.0MPa, weight space velocity is 6.0 hours
-1, hydrogen/hydrocarbon mol ratio is 8.0.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.
10 grades of adsorption separation unit employings are simulation moving-bed, filling sorbent material in the moving-bed, and the fractionation by adsorption service temperature is 130 ℃.
The Crystallization Separation unit adopts suspension crystallization to separate, and Tc is-15 ℃.
Operate according to the parameter that provides in accompanying drawing 2 described technical process of the present invention and the example, the treatment scale of p-Xylol production equipment unit sees Table 7, and the output of product p-Xylol and benzene sees Table 8.
Table 7 embodiment 3 each cell processing scale table
| The unit title | Heavy aromatics takes off alkyl unit | Isomerization unit | Adsorption separation unit | The Crystallization Separation unit | The dimethylbenzene fractionation unit |
| Scale, kg/hr | 38505 | 161209 | 210658 | 54752 | 235861 |
Table 8 embodiment 3 product productions and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 49294 | 29067 | 78361 |
| Purity, % by weight | 99.80 | 99.94 |
The result shows, uses the technology of the present invention, and with the listed aroamtic hydrocarbon raw material of table 1, the ultimate production that technique of the present invention can be produced p-Xylol and benzene is 78361 kg/hrs.The treatment scale of xylene isomerization unit, adsorption separation unit and dimethylbenzene fractionation unit has descended respectively 26%, 23% and 27%, has obviously reduced the design scale of device.Plant energy consumption is 21263 * 10
6Joule/ton (p-Xylol+benzene), with respect to 26579 * 10 of Comparative Examples
6Joule/ton (p-Xylol+benzene), Energy Intensity Reduction 20%.
[comparative example 1]
By flow process shown in Figure 1, still with typical reformation de-pentane oil C in the table 1
6A～C
10 +The flow rate of A logistics is basic data, investigates the ability that traditional Aromatic Hydrocarbon United Plant that contains toluene disproportionation and alkyl transfering process unit is as shown in Figure 1 produced p-Xylol and benzene.The material feeding of its disproportionation and transalkylation, isomerization unit and extraction situation see Table 9, and the treatment scale of each unit sees Table 10, and the output of product p-Xylol and benzene sees Table 11.
Table 9 comparative example 1 process stream table
Table 10 comparative example 1 each cell processing scale table
| The unit title | Disproportionation and transalkylation | Isomerization unit | Adsorption separation unit | The dimethylbenzene fractionation unit |
| Scale, kg/hr | 111988 | 219438 | 274572 | 323269 |
Table 11 comparative example 1 product production and purity table
| Product | P-Xylol | Benzene | Summation |
| Output, kg/hr | 54316 | 22751 | 77067 |
| Purity, % | 99.80 | 99.94 |
The result shows, traditional aromatic hydrocarbons production technique reaction aroamtic hydrocarbon raw material listed such as table 1, and the total amount that the worker has produced p-Xylol and benzene is 77067 kg/hrs, plant energy consumption is 26579 * 10
6Kilojoule/ton (p-Xylol+benzene).
Claims (3)
1. the p-Xylol method of producing may further comprise the 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, under hydro condition, carry out toluene selective disproportionation reaction, generate C8 aronmatic and the benzene logistics that contains p-Xylol after the 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 selective disproportionation of toluene technique unit;
D. send into adsorption separation unit after first strand of C8 aronmatic, second strand of C8 aronmatic and the 3rd strand of C8 aronmatic mix, obtain containing the C8 aronmatic of high density p-Xylol;
E. the C8 aronmatic that contains the high density p-Xylol is sent into the Crystallization Separation unit, obtains the p-Xylol product, and the 4th strand of C8 aronmatic, and the 4th strand of C8 aronmatic turns back to adsorption separation unit;
Wherein, 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, and the liquid weight air speed is 0.8～8 hour
-1
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, and weight space velocity is 0.8～10 hour
-1
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-15～5 ℃, and washings/crystal weight ratio is 0.05～0.5; The weight concentration of p-Xylol is 75～95% in the C8 aronmatic of high density p-Xylol; The weight concentration of p-Xylol is 〉=99.8% in the p-Xylol product.
2. the described p-Xylol method of producing according to claim 1, it is characterized in that the used catalyzer in selective disproportionation of toluene unit 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 the magnesium, and its consumption is 0.005～5% by weight percentage.
3. the described p-Xylol method of producing according to claim 1, it is characterized in that it is at least a molecular sieve that is selected among beta-zeolite, mordenite or the MCM-22 that carbon nine and above aromatic hydrocarbons thereof take off the used catalyzer of alkyl technique unit, the metal of bismuth-containing or its oxide compound in the catalyzer, its consumption are 0.005～5% by weight percentage.
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