Title of Invention	A PROCESS FOR PRODUCING XYLENE
Abstract	An improved process for producing xylene from feedstock containing C9 alky] aromatic hydrocarbons with the aid of a catalyst capable of disproportionation, rearrangement, and dealkylation, wherein said improvement comprises performing the reaction in the presence of an aromatic hydrocarbon having one of more ethyl groups in an amount of 5 to 50 wt%.

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BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to a process for . producing xylene from feedstock containing C9 alkyl aromatic hydrocarbons (which are generally regarded as useless) by disproportionation, transalkylation, and dealkylation, said process being carried out in the presence of a specific aromatic hydrocarbon whose concentration is within a certain range. Description of the Prior Art: Xylene as feedstock for p-xylene and o-xylene isusually produced from naphtha by reforming, followed by extraction and fractionation, or by extraction and fractionation of cracked gasoline as a by¬product of thermal cracking of naphtha. Xylene is also produced on an industrial scale from toluene or a mixture of toluene and Cg aromatic hydrocarbons by disproportionation and transalkylation.of ■ alkyl groups. However, toluene itself is an industrially important raw material for the production of benzene by dealkylation. On the other hand, there has been disclosed in Japanese Patent Publication Nos. 48413/1974 and 16782/1975 aprocess for producing Cio aromatic hydrocarbons (such as durene) from Cg aromatic hydrocarbons 10 0£c mi (including propylbenzene isomers, methylethylbenzene isomers, and trimethylbenzene isomers) by disproportionation and transalkylation. However, nothing is known about the efficient production of xylene from feedstock composed mainly of C9 aromatic hydrocarbons. There is a known process for industrially producing xylene from toluene and C8 aromatic hydrocarbons with the aid of amorphous silica-alumina catalyst. (PETROTECH, 2 (12) 1160. 1970) This process suffers the disadvantage that the catalyst has to be continuously regenerated by using a moving bed so as to maintain a certain level of yield and activity. There has been reported a process for producing xylene from C9 aromatic hydrocar.bons alone or in combination with toluene with the aid of a zeolite catalyst. (J. Das et al., Catalysis Letter 23 (1994). I. Wang etal.. Ind. Chem. Res. 29 (1990) 2005) This process is not necessarily satisfactory in yields. So far, there has been no efficient process for producing xylene from Cg aromatic hydrocarbons. SUMMARY OF THE INVENTION it is an object of the present invention to provide a process for efficiently producing xylene by disproportionation, transalkylation, and dealkylation from feedstock composed mainly of substantially toluene-free C9 aromatic hydrocarbons generally regarded as useless. The present inventors found that it is possible to produce xylene efficiently from feedstock composed mainly of substantially toluene-free C9 aromatic hydrocarbons by disproportionation, transalkylation, and dealkylation if an aromatic hydrocarbon having one or more ethyl groups is present in a certain amount. The gist of the present invention resides in an improved process for producing xylene from feedstock containing C9 alkyl aromatic hydrocarbons with the aid of a catalyst capable of disproportionation, transalkylation, and dealkylation, wherein said improvement comprises performing the reaction in the presence of an aromatic hydrocarbon having one or more ethyl groups in an amount of 5 to 50 Wt%. DETAILED DESCRIPTION OF THE INVENTION The process of'the present invention employs feedstock composed mainly of Cg alkyl aromatic hydrocarbons. It also employs an aromatic hydrocarbon having one or more ethyl groups, which is exemplified by ethyIbenzene, methylethylbenzene. dimethylethylbenzene, and According to the present invention, xylene is produced efficiently from feedstock composed mainly of Cg alkyl aromatic hydrocarbons with the aid of a catalyst capable of aisproportionation, transalkylation, and dealkylation, in the presence of an aromatic hydrocarbon having one or more ethyl groups in an amount of 5 to 50 wt, preferably 15 to 50 wt. The catalyst is not specifically restricted so long as it is capable of disproportionation, transalkylation, and dealkylation. It should preferably be one which contains zeolite. A preferred zeolite is mordenite. The zeolite should contain at least one member selected from the metals belonging to the VIB, VIIB, and VIII Groups, in an amount of 0.001-5 wt^, preferably 0.02-1 wt?^ (as element). A preferred example of the metal is rhenium. The reaction involving the above-mentioned catalyst should be carried out in the presence of hydrogen at 1-6 MPa and 300-550 °C, with the WHSV (weight hourly space velocity) being 0.1-10/hr. Accordingly, the present invention provides a process for producing xylene from a feedstock comprising at least one C9 (alkyl aromatic) hydrocarbon with the aid of a mordenite zeolite catalyst capable of effecting disproportionation, transalkylation and dealkyiation, said catalyst including at least one metal selected from the VIB, VIIB and VIII Groups, in an amount (as element content) of 0.001 to 5 wt% of the total weight of total catalyst, wherein an aromatic hydrocarbon having at least one ethyl group is present in the feedstock in an amount of 5 to 50 wt% of the total weight of the feedstock. EXAMPLES The invention will be described with reference to the following examples. Example 1 A pasty mixture was prepared by mixing from lOS g of powdery synthetic mordenite (sodium form), 45 g of a-alumina, 12 g of alumina sol (containing 10 wt% alumina), 10.5 g of alumina gel (containing 70 wt% alumina), and an adequate amount of deionized water. After kneading for about 2 hours, the pasty mixture was molded into cylindrical pellets, each measuring 1.0 mm long and 1.2 mm in diameter. The pellets were dried at 120t for 16 hours. The dried pellets (50 g in absolute dry condition at 520t ) were baked at 400t for 5 hours in an atmosphere of air. After cooling, the baked pellets were treated with 100 g of 10 wt^ aqueous solution of ammonium chloride at 80-8511 for 1 hour. The treated pellets were strained off the solution and thoroughly washed with water. The pellets were treated with 100 g of 5 vt% aqueous solution of tartaric acid at 80 to 85t for 3 hours. The treated pollets were strained off the solution and thoroughly washed with water. The washed pellets were dipped in 6, 5 g of 5 wt aqueous solution of rhenium(VII) oxide (Re2O7) at room temperature for impregnation with rhenium. The pellets were dried again at 120 t for 16 hours and then baked at 540°C for 8 hours in an atmosphere of air. Thus there was obtained hydrogen ion exchanged mordenite catalyst (A). This catalyst (A) contains 0.25 wt of rhenium (in absolute dry condition at 5201 ). Using this catalyst (A) in a fixed-bed catalytic reactor, xylene was produced from feedstock composedd of trimethylbenzene (TMb for short) as a C9 alkyl aromatic hydrocarbon and methylethylbenzene (ET for short) as an aromatic hydrocarbon having an ethyl group in varied ratios. The reaction conditions are as follows: Temperature : 4001 Pressure 4 MPa WHSV : 2.5 h-1 H2/feedstock : 4.0 mol/mol The results are shown in Table 1, It is noted that the yield of xylene increases as the amount of ET increases up to 50 vt%. However, beyond this limit, the yield of xylene decreases. Example 2 Using the catalyst (A) in a fixed-bed catalytic reactor, xylene was produced in the same manner as in Example 1 from feedstock in which ET was replaced by ethylbenzene (EB for short) or diethylbenzene (DEB for short). The results are shown in Table 2, It is noted that the yield of xylene is favorably affected by both EB and DEB. Example 3 Catalysts were prepared in the same manner as in Example 1 except that the amount of rhenium was varied. Using the catalysts in a fixed-bed catalytic reactor, xylene was produced in the same manner as in Example 1 from the same feedstock as used in Run No. 3 in Example 1. The results are shown in Table 3. It is noted that the yield of xylene increases with the increasing amount of rhenium in the range of 0.01 wt% to 0.02 wt%. The effect of rhenium levels off beyond 0.10 wt%. Example 4 Six catalysts (B to G) were prepared, each containing rhenium, nickel, cobalt, molybdenum, chromium, or tungsten. The first four catalysts (B to E) were prepared in the same manner as in Example 1 by impregnation with an aqueous solution containing each metal element. The last two catalysts (F and G) were also prepared in the same manner as in Example 1 except that the compound shown in Table 4 was incorporated into the catalyst components at the time of mixing. Using each catalyst (B to G) in a fixed-bed catalytic reactor, xylene was produced under the same condition as in Example 1 from the same feedstock is used in Run No. 3 in Example 1 the lesuiis are shown in Table 5. It is noted that the catalyst containing rhenium is most active with the minimal content. Example 5 Three catalysts, each containing a different amount of rhenium, were prepared in the same manner as in Example 1. Using each catalyst in a fixed-bed catalytic reactor, xylene was produced under the same condition as in Example 1 from the same feedstock as used in Run No. 3 in Example 1. The rate of decrease in yield was recorded. The results are shown in Table 6. It is noted that the catalyst becomes less liable to deterioration in proportion to the amount of rhenium contained therein. WE CLAIM: A process for producing xylene from a feedstock comprising at least one Cp(alkyl aromatic) hydrocarbon with the aid of a mordenite zeolite catalyst capable of effecting disproportionation, transalkylation and deaikylation, said catalyst including at least one metal selected from the VIB, VIIB and VIII Groups, in an amount (as element content) of 0.001 to 5 wt% of the total weight of total catalyst, wherein an aromatic hydrocarbon having at least one ethyl group is present in the feedstock in an amount of 5 to 50 wt% of the total weight of the feedstock. The process according to claim 1, wherein the aromatic hydrocarbon having at least one ethyl group is present in the feedstock in an amount of 13 to 30 wt% of the total weight of the feedstock. The process according to claim 1, wherein the metal is rhenium. The process according to claim 3, wherein the mordentie zeolite contains rhenium in an amount (as element content) of 0.02 to 1 wt% by weight of the total weight of total catalyst. The process according to any one of the preceding claims which is carried out under a pressure of 1-6 Mpa and at a temperature of 300-550° C, in the presence of hydrogen, and at a weight hourly space velocity (WHSV)of O. 1-10/hr. 6. A process for producing xylene substantially as herein described and exemplified.

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0320-mas-96 abstract.pdf

0320-mas-96 claims.pdf

0320-mas-96 correspondence-others.pdf

0320-mas-96 correspondence-po.pdf

0320-mas-96 description (complete).pdf

0320-mas-96 form-2.pdf

0320-mas-96 form-26.pdf

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0320-mas-96 form-6.pdf

0320-mas-96 form-9.pdf

0320-mas-96 petition.pdf