CA1185267A - Conversion of xylenes containing ethylbenzene - Google Patents

Abstract

ABSTRACT
Xylenes containing ethylbenzene are contacted with a catalyst comprising an acid type mordenite and a specific acid type zeolite such as, for example, ZSM-5, ZSM-8 or ZSM-11, in vapor phase in the presence of hydrogen, whereby there are performed deethylation of ethylbenzene and isomerization of xylenes.

Description

~L~8S~

WNVERSION OF XYLENES ~ONTAINING ETHYLBE~ZENE

Background of the Inventicn The present invention relates to a catalytic conversion process for xylenes containing ethylbenzene.
Among the xylenes, lt is para-xylene that is in the greatest industrial demand at present, so the isomerization technique for converting ortho- and meta-xylenes which are in less demand into para-xylene ls industrially important.
In general, industrially utilized xylenes are obtained by aromatic extraction and fractional distillation of reaction products from reforming or cracking of naphthas. But all of the crude xylenes thus obtained contain ethylbenzene in addition to ortho-, meta- and para-xylenes. Therefore, ethylbenzene is removed from such crude xylenes by some suitable means, and para-xylene is produced 15 by the combination of separation s~ep and isomerization step.
Ethylbenzene may be removed by direct separation thereof or by reaction thereof for conversion into a more useful compound.
An example or the former is the distillation process wherein, however, it is necessary to perform an ultra-rectification because of a

2~ small differe~ce in boillng point between ethylbenzene and xylenes, alld this necessity results in lncreased equipment cost and running expenses. Thus, the distillatlon process ls disadvantageous from the economic point of view. An example of the latter is a method wherein ethylben~ene is converted to xylenes by using a bifunctional catalyst comprlsing a platinum component and a solid acid component and at the same time there is performed isomerization of the xylenes.
The method of removing ethylbenzene by the reaction is economically ~8~

advantageous because it requires no special equipment. But a further imp~ovement i8 desired because of problems involved therein, for example, platinum used in the above-mentioned bif~mctional catalyst i5 a very expensive noble catalyst, and the conversion of 5 ethylben~ene is re~;tricted by a thermc)dynsmic equilibrium relation between ethylbenzene and xylene isomers.
As the method for overcoming the above-mentioned problems, an lncreasing attention has recently been placed on a conversion process for ethylbenzene into benzene and ethane by using a catalyst 10 comprising a solid acid component and a hydrogenation component.
The hydrodealkylation reaction of ethylbenzene into benzene snd ethane has features such that the improvement of conversion is relatively easy because the reaction scarcely undergoes thermodynaInic restrictions, and that the resulting benzene is easily separable 15 by the distillation process because of a large difference in boiling point from xylenes and has a high added value as a raw material for synthetic fibers and synthetic resins. ~s a catalyst for allowing such reaction to proceed efficiently, the present inventors have proposed a mordenite catalyst containing rhenium and~or phosphorus 20 c r this mordenite catalyst further containing molybdenum, tungsten and/or vanadium, previously in Japsnese Laid Open Patent Publication Nos. 9727/1982, 6~623/1982 and 134423/1982. But, to make this reactlon more eE~iclent, it is desirable to further i!nprove the catalyst activity and selectivity.

25 Summary of the Invention It is an obJect o~ the present invention to overcome the oregoing dlsadvantage3 o~ the prior art.

It is another objece of the present invention to provide a conversion process for xylenes cont~ining ethylbenzene.
It is a furthsr ob~ect of the present invention to provide a process for deethylation of ethylbenzene into benzene and simultaneous isomerization of xylenes efficiently.
The above-mentioned ob~ects of the present invention can be achieved by contacting x~lenes containing ethylbenzene with a catalyst comprising c~n acid type mordenite and an acid type zeolite which exhlbits the X-ray diffraction pattern shown in Table 1 below, in the presenc2 of hydrogen.
Table d (A) 11.2 + 0.2 1~.1 + 0.2 1; 3.86 ~ 0.08

3.7Z + 0.0~
3.S6 + 0.~8 Description of the Preferred Embodiment As the mordenite used in the present invention, there may be employed any of synthetic and natural zeolites having the cryatal structure of mordenite. Of course, a mixture of synthetlc and natural zeolites may be used. The mordenite can be produced, for example, by the process disc]osed in U.S. Patent No.3,436,174 or ~uropean Laid Open Patent Publication No.57,016.
As the zeolite used in the present invention, exhibiting the X-ray dif~raction pattern shown in Table 1, there may be employed, ~852~i'7 for example, ZSM-5 disclosed in U.S. Patel~t No.3,894,106, ZSM-8 disclosed in sritish Patent No.1,334,243, ZS~f-ll disclosed in V.S.
Patent No.3,709,979, Zeta 3 disclosed in German Laid Open Patent Publication No.2,548,695, zeolite prepared without adding an organic substance into reaction mixt~lre, as disclosed in U.S. Patent No.

4,257,885, or zeolite prepared by adding a carboxyl group-containing organic compound into reaction mixture, as disclosed in European Lald Open Patent Publication No.57,016.
Without being restricted to those Just exempll.fied above, any other zeolites are employable provlded they have a structural characteristic exhibiting the X-ray diff~action pattern shown in Table 1. Butj zeolites which exhibit the X-ray diffraction pattern shown in Table 2 below are more preferable;
Table 2 d ~A) ~ (A) _.
11.2 + 0.2 4.27 + 0.08 10.1 + 0.2 3.86 + 0.08 . 6.37 + 0.1 3.75 + 0.08 6.00 + 0.1 3.72 + 0.08

5.71 ~ 0.1 3.66 + 0.08 5.58 + 0.1 3.00 + 0.05 4.37 ~ 0.08 2.00 + 0.05 The SiO2/~1203 mole ratio of the zeolite i8 preferably not less than 10, particularly in the range of 20 to 200 and further 30 to 150.
The weight ratio between the zeolite (hereinafter ~: Ll35%67 referred to as the zeolite ~a)~ which exhibits the ~-ray diffraction pattern shown in Table l, and tha mordenite, both contained in the catalyst used in the present invention, is preEerably in the range of lX to 50~, more pr~ferably 5~ to 30~, in terms of percentage by weight of the zeolite (a) based on the total weight of both zeolites, i.e the zeolite (a~ and the mordenite. The catalyst may contain an additional component or components, for example, an inèrt alumina, other than the two kinds of zeolites described above.
The mordenite and the zeolite Ca~, before their use in the invention, should be treated into acid type. Acid type zeolltes, as well known, have hydrogen ions as cations, and they are obtainPd usually by ion-exchanging at least part of alkali metal ions and/or alkaline earth metal ions of zeolites which contain those exchangeable cations, with hydrogen ions and/or ammonium cations as a hydrogen ion precursor. Generally, the ion-exchange treatment iB carried out by using an aqueous solution which contains an acid and/or an ammonium salt. In this case, both inorganic and organic acids are employable, but the use of inorganic acids i8 more common. Examples of inorganic acids include hydrochloric, nitric, phosphoric and carbonic acids.
2~ Of course, there may be used other inorganic acids provided they contain hydrogen ion. Preferred concentrations of acids vary according to the klnd of acidg used, so it is difEicult to absolutely define such concentrations, but care should be exercised to avoid destruction of the mordenite structure.
Examples of ammonium salts which may be used lnclude inorganic ammonium salts s~ch as ammonium nitrate, ammonium chloride, ammonium sulfatej ammonium carbonate and aqueous ammonia, as well as ammonium salts of organic acids such as ammonium formate, ammonium acetate and ammonium citra~e, wi~h lnorganic ammonium salts belng preferred. A~monium salts are used as a solution of preferably 0.05 to ~N, more preferably about 0.1 to 2N.
As the method of such ion-exchange treatment Eor the zeolites using the acid and/or ammorlium salt solution, both batch me~hod and flow method are employable preferably. In case the treatment is made by the batch method, the solid-liquid ratio should be at least a ratio at which the æeolites can fully contact the liquid, preferably about 1 Q/kg or more. ~ treatment time from abo~lt 0.1 to 72 hours i5 sufficient, preerably from about 0.5 to 24 hours, and a treatment temperature below the boiling point is sufficient, but preferably heat is applied to accelerate the ion-exchange rate.
In case the flow method is to be followed, there may be adopted the fixed-bed process and the fluidized-bed process, but it is necessary to give consideration so that there may not occur fluld channelling or the ion exchange treatment may not become non-uniform.
The zeolites after sub~ected to the ion exchange treatment are washed with water, preferably with distilled water, according to elther the batch method or the flow method. In this way, hydrogen ions or a~nonium ions as a hydrogen ion precursor are introduced in the zeolites.
In the cases of the zeolites ZSM-5, ZSM-8 and ZSM-ll, since an organic nitrogen-containing cation is used at the tlme of thelr production, they can be cllanged into acid type zeolltes by allowlng the said organic nitrogen-containing cation to decompose upon calcining for conversion thereof into hydrogen ion, even w~thout application of the lon exchange treatment using the acld and/or ammonium salt solution.

~ ~5;~7 Ihe ratio of hydrogen ions in the catalyst to the entire exchangeable cations is preferably in the range of 30~ to 90~, more preferably 40% to 80%, in terms of gra~ ion equivalent. A too low ratio is not deslrabIe because it would cause deterioration of the reaction activity. A too high ratio is not desirable, either, because a disproportionation reaction as a side reaction would be accelerated although the reaction activity would become higher. The zeolites thus ion-exchanged with hydrogen ions, namelyj the proton type zeolites, if further sub~ected to heat treatment at a high temperaturej beco-ne so-called decationized zeolites. But~ decationized zeolites and proton type zeolites are not always distinguishable clearly from each other and are often used indiscriminately. The acid type as referred to herein include decationized type.
If only the zeolites in the catalyst used in the present invention are acid type zeolites, the remaining cations may be various cations. Particularly, alkaline earth metals are pre~erred because they are effective in improving the reaction selectivity.
To let the zeolites contain alkaline earth metal lons, it is necessary to perform an ion exchange for introducing such ions in addition to the ion exchange for introducing hydrogen ions andlor ammonium ions as a hydrogen ion precursor. The ion exchange for introducing alkaline earth metal ions is carried out by treating the zeolites with a solution which contains a compoulld of an alkaline earth metal. Preferred alkaline earth metals are magnesi.um, calcium, stronti-mm and barium.
In case it is necessary to per~orm the ion exchange for introducing alkaline earth metal ions, this ion exchange treatment may be conducted separately Erom the ion exchange treatment for ~85;~6~

introducing ammonium ions, or both treatments may be carried out at a time.
According to a particularly preferred ion-exchanging method in the preparation of the catalyst used in the invention, first the ion exchange treatnent for introducing alkaline earth metal lons is conducted and then the same treatment for introd~cing hydrogen ions and/or ammonium ions as a hydrogen ion precursor i8 performed by a l1quid recycle type batch process.
In the reaction of the lnvention using the catalyst thus prepared, ethy]benzene :Ls hydrodealkylated for conversion to benzene and ethane. Therefore, lt is preferable that the catalyst used in the invention contain a component having a certain specific hydrogena-tion activity~ Examples of such component include nickel, cobalt, rhenium, molybdenum, tungsten and vanadi~m. Noble metals such as platinum and palladium are not preferable in the reaction of the invention. If a platinum-supported catalyst is used in the reaction of the invention, there occurs a hydrogenation reaction at the benzene nuclei of the xylenes because the hydrogenation activity of platinum is too strong, and therefore s~ch catalyst is not desirable. A
20 preferred amount of rhenium to be added ranges from 0.005 to 3%, more preferably 0.02 to 0.5%, by weight as the rhenium element based on the weight of the entire catalyst. A preferred amount of molybdenum, tungsten or vanadlum to be added ranges from O.l to 10%, more preferably 0.2 to 5~, by weight as the element based on the weight of the entire catalyst. ~ too small amount is not effectlve, while a too large amount causes side reaction, and thus both such amounts are not des1rable.
As the method for adding s~ch metal to the other catalyst 52~

componentsj there may be adopted, for example, a kneading method, impregnatlon method and a method of physically mixing yo~ders with each other. For adding the metal element b~ tho kneadlng method, a compound o the element may be added and ~neaded slmultaneously with mixing of the mordenite and the zeolite ~à) in their granu1ation.
According to the impregnation method, usually, it is possible to support the element by impregnating the zeolites after granulation Lnto a solution containing a compound of the element, follcwed by draining and drying. In the process of the present invention, the impregnation method is preferred. As the solvent for dissolving the compound of the element, there may be used organic solvents such as alcohols, not to mention water. The amount of the element to be added can be ad~usted by suitably selecting the concentration of the compound of the element in the solution.
Examples of compounds of the element which may be used in the invention include, with respect to rhenium, rhenium oxide, perrhenic acid, ammonium perrhenate and rhenium sulf~de; with respect to molybdenum, ammonium molybdate, ammonium paramolybdate, ammonium phosphomolybdate, molybdic acid, molybdenum oxide, molybdenum sulfide and molybdates; and with respect to tungsten, ammonium tung6tate, ammonium phosphotungstate, tungsten oxide, tungsten sulfide, tungsten carbide and tungstates.
Either a fixed bed or a fluldized bed may be used as a reaction apparatus in the present invention, but the former is preferred because of simpler construction and easier operation. In the flxed bed process, it is preferable from the standpoint of catalyst effectiveness factor that the particle diameter of the catalyst be as small as possible, proYided a too small particle ~35%~7 diameter 1s not desirable because it would cause an increased pressure drop. That is, there exists a preferable range of cataly6t diameter, which is from O.OS to 10 mm, more preferably from 0.1 to 2 mm. ~9 the case may be, molding is needèd in order for the 5 catalyst to have such a preferred range of particle diameter, for example, compre~sion molding and extru~ion. ~nd in order t~ lmprove the moldability or impart strength to the catalyst, there may be used a binderj though it goes without saying that the use of binder may be omitted iE molding is attalnable to a satisfactory extent without the binder. Preferred examples of the binder include natural clays such as kaolin, bentonite, montmorillonite and acid clay as well as synthetic products such as silica sol, alumina sol and alumina gel.
The amount of the binder to be added is not re than 70~, preferably not more than 20~, by weight.
The catalyst used in thè present invention is prepared basically through the steps of mixing the two zeolite components, motding and treatment into the acid type, the-order of which steps may be selected suitably. For example, both zeolite powders may each be treated into the acid type, then mixed and thereafter molded to obtain the catalyst, or both zedlite powders may be molded and treated into the acid type each independently and then mixed to obtain the catalyst.
As described above, the catalyst thus prepared is dried and subsequently calclned beore lts use. The drylng is performed at 50 to 250C Eor over 0.1 hour, pre~erably 0.5 to 48 hours, and the calcination is performed at 300 to 700~C Eor over 0.1 hour, preferably at 400 to 600C ~or 0.5 to 24 hours. By this calcination the ammonium lons introduced in the zeolites by the ion exchange treatment 523~7 are converted to hydrogen ions, which in turn are converted to the decatlonized type as the calcination temperature increases, and the catalyst in such a form is also employable effectively.
m e catalyst prepared in the manner described above is used under the following reaction conditions. The operating tempera-ture ranges Erom 300 to 600C, preferably from 350 to 550~C, and the operating pressure ranges`from atmospherlc pressure to 100 kg/cm2 G, preferably from atmospheric pressure to 50 kg~cm2~G. ~le tlme factor W/F tg-cat hr/g-mol feed stock, W: catalyst weight, F: mol feed stock per hour) whlch means the contact time of reaction is in the range of 0.1 to 200j preferably 1 to 100. It is essentlal that hydrogen is present in the reaction system. If the hydrogen concentration is too low, the dealkylation reaction of ethylbenzene will not proceed to a sufficient extent!and a carbonaceous cDmponent will be deposited on the catalyst thus resulting in de~erioration of the catalyst activity with the lapse of time. A too h~gh concentration of hydrogen is not desirable~ eitherj because it would cause an lncrease of hydrocracking reaction. That is, there exists a preferable range of hydrogen concentration, which ls 1 to 50, preferably 3 to 30, 20 ln terms of mol ratio of hydrogen to feed stock ~H2/F).
As the feed stock there is used a mixture of xylenes containing ethylbenzene, wherein the concentratlon of ethylbenzene is not specially limited. The concentratlon of para-xylene in the xylene mixture is preEerably below the thermodynamic equilibrium concentratlon, but lt is of course possible, as one mode of use in the present invention, to use as the feed stock a xylene mixture containing para-xylene of the thermodynamic equilibrium concentration with a view to decreasing the concentration of ethylbenzene.

~ ~s;2gj7 The feed stock may contain other aromatic components~ e.g.
benzene, toluene, trimet~yl~enzene, ethyltoluene, dlethylbenzene, ethylxylene~ provided thelr concentrations should be in a low range.
The following example~ are given to further illustrate the present invention.

Example 1 14.7 g. oE a solid sodium hydroxide and 10.5 g. of tartarlc acid were dissolved in 351 g. of water, then 5.24 g. of a sodium aluminate solution was added to prepare a homogeneous solution.
To this mixed solution was then added, slowly with stirring, 66.0 g.
of Rilicic acid powder avallable commercl~lly as white carbon to prepare a homogeneous, slurried, aqueous r2action mixture having the following composition in terms of mol }atios:
SiO2/~1203 100 H20/SiO2 20 OH-/SiO2 0.24 TA/~1203 7 (TA: Tartàric acid) The mixture was charged into an autoclave having a capacity of 500 ml. and the autoclave was closed. Then, heatlng was made to 160C with stlrring and crystallization was allowed to take place for 72 hours. Thenj after cooling, the product was taken out of the autoclave, wnshed with di~tilled water and filtered until the pH was almost neutral, and then dried overnight at 110C. The product thereby obtained was a zeolite havlng the X-ray diffraction pattern shown ln Table 3. Chemlcal composition of the zeolite upon analysis proved to be 1.3 Na20-A1203, 48.7 SiO2 in a dehydrated state.

S~6~

Table 3 X-ray diffraction pattern d ~ lOOIIIo dt~I lOOI/Io 11.18 39 3.8280 10.10 32 1 3.76~ll 9.82 13 1 3.7347 7.49 3 1 3.6629

6.75 5 1 3.495 6.41 10 3.4514 6.04 14 3.366 5.73 11 1 3.3214 5.60 12 1 3.0614 5.40 3 3.00 `13 5.18 2 2.87 4 5.06 5 2.~4 5 5.01 6 2.62 4 4.64 6 2.49 8 .~ 4.39 8 2.02 10 4.29 14 2.00 11 4.11 13 1.92 3 L~ ~ L ~

Example 2

7~49 8. oE a solid sodium hydroxide and 18.8 g. of tartaric acid were dis~olved ln 325 g. of water, then 52.4 g. of a sodium aluminate solution was added to prepare a homogeneous ~olution.
_ 13 11~3S;~

To t~s mixed solution was then added, slowly with stirring, 66.0 g.
of silicic acid powder to prepare a homogeneous, slurried, a~ueous reactlon mixture having the following composition in terms of mol ratlos:
SiO2/A1203 ~0 ~l20/SiO2 20 OH-/SiO2 0.275 TA/A1203 1.25 (TA: tartaric ac-ld The mixture wa~ charged into an autoclave having a ~0 capacity of 500 ml. and the autoclave was closed. Thenj heating was made to 160~C wlth stirring and crystallization was allowed to take place for 48 hours. Then, after cooling, the product ~as taken out of the autoclave, washed with distilled water and filtered untll the pH wa~ almost neutral, and then dried overnight at llO~C. The product thereby obtained as a rdenite type ~eolite having the X-ray diEfractlon pattern shown in Table 4. Che~ical composition of the zeolite upon analysls proved to be O.9S Na20 Al203,9.7 SiO2 dihydrated 8 tate.

_ 14 52~;i'7 Tabla 4 X-ray diffraction pattern d (~) ¦ lOOI~Io l d C~ I lOOI/Io 13.86 22 3.24 39 10.~2 7 3.21 47 9.18 55 3.17 8 6.64 34 3.12 4 6.45 26 2.90 27 6.13 10 2.72 2 5.85 17 2.64 2 5.15 3 2.56 8 5.08 3 2.52 14 l 4.55 38 1 2.47 4 i 4.16 4 2.44 4 4.01 77 2.28 2 3.86 9 2.23 3 3.78 13 2.16 2 3.65 3 2.04 8 .. 3.55 11 1.96 8 3.49 100 1.92 3 ~ l ~8 Example 3 2.2 g. of aluminum s~late ~A12(S04)3-18H202, 11.3 g- of aulf~ric acid and 15 g. of n-propylamine were dls~alved in 231 g. of ~ater, then 135 g. of ~odium ailicnte No.3 waq added ~lowly with _ 15 .

stirring to prepare as homogeneous a gel-like slurry as possible. Ihe slurry was charged ~nto an autoclave having a capacity of 500 ml. and the autoclave was closed. Crystallization was sllowed to take place at 160C Eor 72 hours with stirring. Then, aEter cooling, the product was wa~hed with distilled water and filtered. The water-w ~qhing and ~iltration were repeated until the washing was almost neutral, followed by drying overnight at about 110C. The product thereby obtained was zeolite ZSM-5 containing organic ammonium cations with a sio2/A12o3 mol ratio of 137 and having the X-ray diffraction pattern shown in Table 5.

i2~7 Ta~le 5 X-ray di~fractl~n pattern d CA)100I/Io ~ 1 100I/Io 11.07 60 3.48 5 10.01 36 3.4~ 12 9.72 12 3.35 7 7.45 2 3.31 11 6.71 6 3.25 4 6.37 11 3.14 3 6.00 11 3.05 9 5.70 9 2.99 11 5.58 9 2.94 5 5.36 2 2.86 3 5.14 3 2.78 2 5.03 4 2.73 5 _ 15 4.98 6 2.68 2 4.88 1 2.61 4 4.62 7 2.51 3 .. 4.36 9 2.49 5 4.26 14 2.42 3 4.09 5 2.39 3 4.01 6 2.019' 3.85 100 1.99 9 3.81 66 1.95 3 3.74 34 1.92 3 3.71 46 1.87 3 3.65 j 25 _ 17 ~S26~
Examples 4-7 10 parts by weight (on absolute dry basis) powder of the crystalline aluminosilicate zeolite prepared in Example 1 was mixed with 45 parts by weight (on absolute dry basis) of a commercially available synthetic sodium type mordeni~e ZEOLON 100-NA (trade mark) powder manufactured by Norton Company and 45 par-ts by weight (on absolute dry basis) of alumina powder as a diluent. Then, 15 parts by weight (as A1203) of alumina sol as a binder was added to the powder mixture. After kneading, the kneaded mass was extruded -through a screen of 1 mm-~. After the extrusion, the molded particles were dried overnight at about 110C, then classified to 12-24 mesh and thereafter calcined in a muffle furnace at 500C for 2 hours. This molded product upon analysis proved to contain 1.06 meq/g of exchangeable sodium.
100 g. (on absolute dry basis) of the molded product was dipped in a solution of 10 g. ammonium chloride dissolved in 200 ml. of distilled water and ion-exchanged with ammonium ions for about 1 hour with stirring at times in a water bath at about 90C, then thoroughly washed with distilled water and dried overnight at about 110C. The so--treated produc-t upon analysis proved to contain 0.703 and 0.297 meq/g of exchangeable ammonium and sodium, respect-ively. It was then calcined in a muffle Eurnace at 500Cfor 2 hours. The catalyst thus prepared will be referred to hereinafter as catalyst "A".
On the o-ther hand, 20 g. (on absolute dry basis) of a likewise treated product after going through the ion exchange with ammonium ions and subsequent drying was impregnated in 40 m:L. of an aqueous perrhenic acid containing 0.02 g. of rhenium as metal and .~ - 18 -35;~6'7 allowed to stand for 30 minutes at room temperature, then allowed to drain and dried overnight at about 110C. The dried product W89 then calcined in a muffle furnace at 500DC for 2 hours. The catalyst thus prepared will be referred to hereinafter as catalyst "B".
Vsing an aqueous ammonium molybdate solution containing 0.20 g. of molybdenum as metal in place of the aqueou~ perrhenic acld solution, a catalyst was prepared in the same wayj which~will be referred to hereinafter as catalyst "C".
Furthermore, using an aqueous ammonium tungstate solution containing 0.20 g. of tungsten as metal in place of the aqueous perrhenic acid solution, a catalyst was prepared in the same way, which will be referred to hereinafter as catab st l!D" .
Thenj using the catalysts ~, B, C and D, feed stocks each comprising ethylbenzene and xylenes were treated under the conditions shown ln Table 6. The results are as set out ln the same table.

EXamples 8-11 ' 7.5 parts by wel~ht (on absolute dry basis~ of the zeollte powder prepared in Example 1 and 92.5 parts by weight ~on dbsolute dry ba31s) of the mordenite type zeolite powder prepared in Example 2 were mixed together, then 15 parts by weight Cas Al203) of alumina 801 as a blnder was added to the powder mixture. After kneading, the kneaded mass was extruded through a screen of 1 Imn ~, then the molded particles were dried overnight at about 110C and subsequently class:lfied to :12-24 mesh, followed by calcining in a muffle furnace at 500C for 2 hours. This molded product upon analysi~ proved to contain 2.07 meq/g of exchangeable sodium.

~L~85Z67 40 g. (an absolute dry basis2 of the molded product was dlpped in a solutlon of 4.0 g. ammonlum chloride dissolved in 80 ~L.
of distilled water and ion-exchanged with ammonium ions for about 1 hour with stlrring at tlmes in a water bath at about 90C~ then thoroughly washed with distilled water and dried overnight at about 110C. The 30-treated product upon analysis proved to contain 1.26 and 0.70 meq/g of exchangeable ammonium and sodium, respectively.
It was then calclned ln a muffle furrlace at 500~C for 2 hours. The catalyst thus prepared will be referred to hereinafter as catalyst ~'E~.
On the other hand, 40 g. (on absolute dry basiY~ Oc the lded product was dLpped in 80 snl. of an aqueous solutlon containing 5~ by weight of calcium nitrate and ion-exchanged for about 1 hour with stirring at times on a hot water bath at about 90C. Thi6 treatment with the calcium nitrate solution was repeated three times.
Thereafter, the so-treated product was wa~hed thoroughly wi~h dlstllled water, then dipped in 180 ml. of an aqueous solution containing 4.0 g. of asnmonium chloride and treated for about 1 hour with occasiona} stirring in a water bath at about 90C, followed by thorough washing with distilled water and subsequent drying over-nlght at about 110C. The treated product upon analysis proved to contain 1.00, 0.89 and 0.13 meq/g of exchangeable asmmonium, calcium and sodLum, respectively. 20 g. (on absolute dry basis) of the treated product was impregnated in 40 s~L. of an aqueous perrhenlc acLd solutlon contalnlng 0.02 g. of rhenium as metal and allowed to ~tand for 30 sninutes at room temperature, followed by calcinlng in a muffle Eurnace at 500C for 2 hours. The catalyst thus prepared ~ill be hereinafter referred to ~g catalyst "F".
_ 20 5;~7 Furthermore, 40 g. ~on absolute dry basis~ of the molded product was treated using magnesium nitrate in place of calcium n~trate and subsequently treated with the aqueous ammonium chloride soiution and the aqueous perrhenic acid in the same way as abo~e to prepare a catalyst, which will be referred to hereinafter as catalyst "G".
~ sing strontium nitrate in place of calcium nitrate, a catalyst was prepared in the same manner as above, which will be reEerred to hereinafter as catalyst 1~
A conversion reaction of xylenes containing ethylbenzene was carried out using the catalysts E, F, G and H under the conditions shown in Table 6. The results are as set out in the same table.

Examples 12 and 13 40 parts by welght ton absolute dry basis) of the zeolite ZSM-5 powder prepared in Example 3 and 60 parts by weight ton absolute dry basis~ of the mordenite type zeolite powder prepared in Example 2 were mixed together, then 15 parts by weight Cas A1203) of alumlna 801 as a binder was added to the powder mixture: After kneading, the kneaded mass was extruded through a screen of 1 ~m-~
then the molded particles were dried overnight at about 120DC andthereafter classlfled to 12-24 mesh, followed by calclnlng in a muffle furnace at 500C for 2 hours. 40 g. (on absolute dry basis) of this molded product was dipped ln a solutlon of 6.0 g. ammonium chlorlde dissolved in 80 ml. of dlstllled water and ion-exchanged wlth ammonlum ions for about 1 hour with occasional stirring in a water bath at about 90C, followed by thorough washing with distilled water, drying oYernight at about 110C'and subsequent calcining in a _ 21 muffle furnace at 500C for 2 hours. The catalyst thus prepared will be referred to hereinafter as catalyst "I".
On the other hand, 40 g. Con absolute dry ~asis~ of the molded product was dipped in 80 ml. of an aqueous solution containing 5X by weight of magnesium nitrate and ion-exchanged ~or about 1 hour with occaslonal stirring ln a water bath at about 90C. Thi~
treatment with the aqueous magnesium nitrate solution was repeated five times. Thereafter, the so-treated product was washed thoroughly with distilled water, then dipped in 80 ml. of an aqueous solution contain~ng 6.0 g. of ammonium chloride and ion-exchanged for about 1 hour with occasional stirring in a water bath at about 90C, followed by thorough washing with distilled water and subsequent drying overnight at about 110C. Exchangea~le ammonium, magnesium and sodlum contents upon analysis proved to be 0.82, 0.45 and 0.10 meqtg, respectively; 20 g. ~on absolute dry basis~ of this treated i product was impregnated in 40 ml. of an aqueous perrhenic acid solution containing 0.02 g. of rhenium as metal and allowed to stand for 30 minutes at room temperature, then allowed to drain and d~ied overnlght at about 110C, then calcined in a muffle furnace at 500C for about 2 hours. The catalyst thus prepared will be referred to herelnafter as catalyst "J".
Using the catalysts I and J, a conversion reaction of xyleneq was carried out under the conditions shown in Table 7.
The results are as set out in the same table.

Example 14 100 g. (on absolute dry basis~ of the mordenite type zeolite powder prepared in Example 2 was dipped in 500 ml. o~ an ~8~Z6~

aqueous solution containing 5.0% by weight of calcium nltrate and ion-exchanged for about 1 hour with occasional stirring in a water bath at about 90C, then filtered and again sub~ected to t~e ion exchange treatment with the aqueous calcium nitrate solution, which operation was repeated five times, followed by thorough washing with distilled water 50 g. ~on absolute dry basis) of the mordenlte type zeolite powder prepared in Example 2 thus ~on-exchanged with calcium ions was dipped in an aqueous solution containing 5.0 g. o ammonlum chloride and ion-exchanged with c~mmonium ions for about 1 hour with occasional stirring in a water bath at about 90C, followed by thorough washing with distilled water and subsequent drying overnlght at about 110 C.
30 g. ~on absolute dry basis~ powder of this mordenite type zeolite thus ion-exchanged with the aqueous ammonium chloride solution was mixed with 20 g. Con absolute dry basis) of the ZSM-5 powder prepared in Example 3, To this powder mixture were added 75 g. of Alumina sol tA1203 content: 10 wt.%~ as a binder and lO ml.
of an aqueous perrhenic acld solution containing 0.06 g. of rhenium as metal, followed by kneading. The kneaded mass was extruded through a screen of 1 mm-~, then the molded particles were dried overnight at about 110C and then classiEied to 12-24 mesh, followed by calcining in a muf1e furnace at 500C for 2 hours. The catalyst thus prepared will be referred to hereinafter as catalyst "K".
Using the catalyst K, a conversion reaction of xylenes containing ethylbenzene was carried out under the conditions shown in Table 7. The results are as set out in the same table.

523~7 Comparatlve Examples 1 and 2 60 parts by we~ght Con absolute dry basls? of the mordenite type zeolite powder prepared in Example 2 and 40 parts by weight ton absolute dry basisl of alumina powder as a diluent were mixed together, then to thls powder mixed was added 15 parts by weight Cas A1203) of alumina sol as a binder, followed by kneading.
nle kneaded mass was extruded through a screen of 1 mm-~, then the molded particles were dried overnight at about 110C and then classified to 12-24 mesh, followed by calcining in a muffle furnace 10 at 500C for 2 hours. 20 g. Con absolute dry basis~ of this molded product was dipped in 40 ml. of an aqueous solution containing 2.0 g.
of ammonium chloride and ion-exchanged with ammonium ions for about 1 hour with occasional stirring in a water bath at about 90C, tfien washed thoroughly with distilled water and dried overnight`at about 15 110C, ~ollowed by calcining ln a muffle Eurnace at 500C for 2 hours.
~he catalyst thus prepared will be referred to hereinafter as catalyst "M".
40 parts by weight ~on absolute dry basis~ of the ZSM-5 yowder prepared in Example 3 and 60 parts by weight Con absolute dry basis) of alumina powder as a diluent were mixed togehter, then to this powder mixture was added 15 parts by weight (as A1203) of alumina sol as a binder, followed by kneading. The kneaded mass was extruded through a screen of 1 mm-p, then the molded partlcles were dried overnight at about 110C and then classiEied to 12-24 mesh, followed by calcining in a muEfle furnàce at 500C for 2 hours. ~his mo]ded product was treated with the aqueous ammonium chloride solutlon in the same way as above to prepare a catalyst, which catalyst will be _ 24 ~, ~

~352~7 referred to here~nafter ss catalyst "L".
Using the catalysts L and M, a conversion reaction of xglenes containing ethylbenzene was carried out under the condltions shown in Table 7. The results are as set out in t~e same table.
Reerence to Table 7 shows that the catalyst L nffords a hlgh ethyl-benzene conversion but a low isomerization to para-~ylene and t~at the catalyst ~ afords only a low ethylbenzene conversion.

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U~ O Ul o ~ote~ C7- : non-aromatlc components of Cl - C7 BZ : benzene TOL : toluene EB : ethyl~enzene XY ~ xylenes PX : para-xylene MX : met~-xylene OX : ortho-xylene ET ethyltoluene TMB : trimethylben7ene DEB : diethylbenzene EX : ethylxylene _ 28

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A conversion process for xylenes containing ethylbenzene, characterized in that said xylenes containing ethylbenzene are contacted with a catalyst in the presence of hydrogen, said catalyst comprising an acid type mordenite and an acid type zeolite which exhibits the X-ray diffraction pattern:
wherein the weight ratio of said zeolite and said mordenite is in the range of 1% to 50% in terms of a percentage by weight of the former based on the total weight of both said zeolites.

2. A conversion process according to claim 1, wherein the ratio of hydrogen ions in said catalyst is in the range of 30% to 90% in terms of gram ion equivalent based on the total exchangeable cations of both said zeolites.

3. A conversion process according to claim 2, wherein said exchangeable cations of both said zeolites are mainly hydrogen ions and alkaline earth metal ions.

4. A conversion process according to claim 1, wherein said catalyst further contains rhenium, molybdenum, tungsten, vanadium, or a compound thereof.

5. A conversion process according to claim 4, wherein the content of rhenium or a compound thereof is in the range of 0.005 to 3.0 percent by weight as element based on the total weight of said catalyst.

6. A conversion process according to claim 4, wherein the content of molybdenum, tungsten, vanadium, or a compound thereof is in the range of 0.1 to 10 percent by weight as element based on the total weight of said catalyst.

7. A conversion process according to claim 1, wherein said catalyst consists mainly of said mordenite and an acid type zeolite which exhibits the following X-ray diffraction pattern:

8. A conversion process according to claim 1, wherein said zeolite is ZSM-5, ZSM-8, ZSM-11, Zeta-3, a zeolite prepared without adding an organic substance into reaction mixture, or a zeolite prepared by adding a carboxyl group containing organic compound into reaction mixture.

9. A conversion process according to claim 1, wherein the conversion reaction comprises deethylation of ethylbenzene and isomerization of xylenes.

10. A conversion process according to claim 1, wherein the conversion reaction is carried out at a temperature in the range of 300° to 600°C and at a pressure in the range of atmospheric pressure to 100 kg/cm2.G.

11. A conversion process according to claim 1, wherein the amount of hydrogen is in the range of 1 to 50 moles per mole of said xylenes containing ethylbenzene.