US2349834A - Treatment of hydrocarbons - Google Patents

Description

hydrocarbons.

Patented May 30, 1944 UNITED STATES PATENT OFFICE 2,349,134 g TREATMENT or nrmrocamaons Louis Schmerling and Vladimir N. Ipatiefl. Chicago, Ill., assignors to Universal Oil Product: Company, Chicago, 11]., a corporation of Delaware v No Drawing. Application April 12, 1941, Serial No. 388,270

9 Claims. (Cl. 260-672) This invention relates to the treatment of be converted into the mono-alkyl aromatic hydrocarbons. 'Xylenes and higher methylated benzenes are also obtained from the coking of coal in quantities in excess of the usual demands for them. Also, poly-alkyl aromatic hydrocarbons in other synthetically produced hydrocarbon mixtures may be of less value than the corresponding lower boiling and less-highly alkylated derivatives.

In one specific embodiment the present invention comprises a. process for producing substantial yields of mono-alkyl aromatic hydrocarbons from poly-alkyl aromatic hydrocarbons which comprises subjecting said poly-alkyl aromatic hydrocarbons, a non-alkylated aromatic hydrocarbon, hydrogen, and hydrogen chloride to .contact with a catalyst comprising essentially 'a higher methylated benzenes may be converted into toluene; while di-ethyl benzene, tri-ethyl benzene, and other poly-ethyl benzenes may be changed into mono-ethyl benzene utilizable in the production of; styrene, which in turn may be converted into resins or rubber-like substances. Other poly-alkyl aromatic hydrocarbons may similarly be converted into mono-alkyl aromatic hydrocarbons.

Thus xylenes, mesitylene, and- Shifting of allayl groups from one molecular nucleus to another has previously been observed in the presence of aluminum chloride or ferric chloride catalysts particularly in the treatment or xylenes as illustrated by the following equations: v

1 CH C H CH CsH (CH2): yfene i), "Eolfrene Trimethyl- A benzene (2) C|Hl(CHI)l CcHg 2CH|CH1 Xylene Benzene Toluene Thus a poly-alkyl aromatic hydrocarbon may be used alone as indicated by a di-alkyl hydrocarbon, xylene, in Equation 1 or it may be mixed with an additional quantity of another aromatic hydrocarbon, usually a non-alkylated aromatic hydrocarbon as shown in Equation 2. For example, in the treatment of xylenes the addition of benzene increased the yield of toluene probably because the migrating methyl group can thus reactmore readily with benzene than with the xylene. Mesitylene and more highly alkylated aromatic hydrocarbons may also be converted into less highly alklated aromatic hydrocarbons such as toluene and xylenes. 4 a

As a catalyst for the process of the present invention zinc chloride has theadvantage over aluminum chloride used for the same purpose in that the zinc chloride forms with aromatic hydrocarbofis' substantially no sludge-like -complexes, generally termed lower layer complexes. The substantial absence of sludge formation thus permits continuous operation as well as a higher yield of desired mono-alkyl conversion product. Furthermore all of the desired product is present as a hydrocarbon liquid free from lower layer which may be washed with caustic to remove hydrogen chloride and then distilled directly, whereas with aluminum chloride catalyst muchof the hydrocarbon is in the sludge or lower layer which must be hydrolyzed before all of the mono-alkylated aromatic hydrocarbon product is available for washing and distillation. Such hydrolyzing treatment also destroys the aluminum chloride, but used zinc chloride catalyst may be regenerated by extracting with water,

filtering if necessary, and either evaporating the in anhydrous condition, zinc chloride is not harmed substantially by water. Accordingly it may be dissolved therein and later deposited upon a suitable carrier.

While zinc chloride may be used as catalyst in the form of the solid salt, in molten condition, or in aqueous solution, it is preferably supported by or composited with a carrier such as alumina, a silica-alumina composite, raw or acid-treated clays, diatomaceous earth, silica-gel, charcoal, etc. The preferred carrier for zinc chloride, however, is alumina, or a substantially inert material containing alumina or composited with a substantial proportion of alumina. The different carriers or supports which may be employed are not necessarily equivalent in their action.

The proportion of zinc chloride and carrier may be variedas desired to make catalyst composites of different activities. Thus it has been found possible and practical to make stable granular catalysts resistant-to disintegrating influences by using from about 5 to about 50% by weight of zinc chloride and from about 95 to about 50% by weight of activated alumina or an alumina-containing carrier. These materials in finely powdered form, after thorough mechanical mixing, may be subjected to drying, pelleting, and heating operations to produce formed p ticles of catalyst suitable for use as reactor filling material. A suitable carrier may also be impregnated with an aqueous solution of zinc chloride, dried, and calcined at a temperature between about 300 and about 350 C. to form a 'zinc chloride-carrier composite suitable for use in promoting the dealkylation of poly-alkylated aromatic hydrocarbons to mono-alkylated aromatic hydrocarbons.

De-alkylatlons'of poly-alkylated aromatic hydrocarbons of the types hereinabove set forth are effected preferably in the presence of hydrogen and/or of hydrogen chloride. There is little or no carbon formation upon the catalyst when the de-alkylatlon reaction is carried out under hydrogen pressure but carbon formation does ocour to a substantial extent in the absence of hydrogen. By using high hydrogen pressure in the presence of a catalyst containing zinc chloride. .mono-alkylated aromatic hydrocarbon will be formed not only by de-alkylation but also by destructive hydrogenation of the poly-alkylated aromatic hydrocarbon. Further, the introduc tion of hydrogen chloride to the reaction mixture promotes the de-alkylation reaction to give a substantially higher yield of mono-alkylatd arc matic hydrocarbon per pass over the cataly tli'ign is obtained in the absence of hydrogen chlor e.

In de-alkylating a poly-alkylated aromatic hydrocarbon according tothe process of the pres-. ent invention, the exact method of procedure depends unon the nature of the hydrocarbons being treated, the activity of the catalysts. and other factors. A simple procedure utilizable in 'the case of a poly-'alkylated aromatic hydrocarbon which is normally liquid or if solid is readily soluble in the added aromatic hydrocarbon or in a substantially inert liquid. consists in contacting the poly-alkylated aromatic hydrocarbon or its solution with a zinc chloride-carrier composite preferably in the presence of both hydrogen and hydrogen chloride. The reaction temperature used depends upon the nature of the alkyl groups present in the poly-alkylated aromatic hydrocarbonn For poly-methyl and polyminum chloride and ferric chloride must be kept ethyl aromatic compounds 9. temperature of from about 300 to about 500 C. is suitable; while for poly-isopropyl derivatives and other polyalkylated aromatic compounds containing more than 3 carbon atoms in the alkyl side chains, a

lower temperature may be used from about 100 to about 400 C. Although zinc chloride melts at about 365 C. itmay nevertheless be employed on a carrier such as alumina at a temperature as high as about 425 C. without substantial loss of zinc chloride therefrom. At higher temperatures of operation, zinc chloride may be employed in molten condition. The operating pressure-is generally above atmospheric and up to about 300 atmospheres maximum under the conditions of operation.

Intimate contact of the poly-alkylated aromatic hydrocarbon or mixture of non-alkylated and poly-alkylated aromatic hydrocarbons with the catalyst is effected by passing the reaction mixture through a fixed bed of the granular catalyst containing zinc chloride or the reacting component or components may be mixed with finely divided catalyst in a substantially fluid type of operation. While the method of passing the aromatic and poly-alkylated aromatic hydrocarbons through a suitable reactor "containing the granular catalyst is generally customary procedure, the de-alkylation reaction may also be effected in a closed vessel in which some of the reacting constituents are in liquid or fluid phase and in which the catalyst is preferably in finely divided form and is maintained in dispersion or suspension by some method of agitation. Reacting constituents may also be contacted in mixed phase to effect a similar type of reaction. The choice of operating procedure is circumstances as the temfound to be most effective dependent upon such perature and pressure for producing the desired conversion to a monoalkylated aromatic hydrocarbon.

' In general the products formed by subjecting a poly-alkylated aromatic hydrocarbon to dealkylation are separated into the desired monoalkylated aromatic hydrocarbon, incompletely converted poly-alkylated aromatic hydrocarbons, and possibly an excess of non-alkylated aromatic hydrocarbon, and then the incompletely converted pcly-alkylated aromatic hydrocarbons and excess of non-alkylated aromatic hydrocarbon are returned to the process and mixed with additional quantities of the fresh reactants being charged to contact with the zinc chloride-carrier catalyst contained in the de-alkylating reaction zone. Also di-alkyl aromatic hydrocarbons and other 'poly-alkyl derivatives may be separated from the reaction mixture as desired products of the process in addition to the mono-alkyl aromatic compound hereinabove set 4 forth.

The following examples are given to illustrate the character of results obtained by the use of the presentprocess, although the data presented are onlyfrom selected cases and are not introduced with the intention of unduly restricting the generallybroad scope of the invention:

ing 25% by weight of zinc chloride and by weight of alumina were placed in an autoclave together with the amounts of benzene and hy,

drogen chloride indicated in Table I. after which hydrogen or nitrogen was added to an initial pressure of atmospheres. The charged autoclave was then heated for 4 hours at 400 C. with the results shown in Tablefi which indicates the yields of benzene, ethyl benzenepand diethyl benzene based upon the tri-ethyl benzene charged.

I TABLE I De-ethylation of tri-ethyl benzene Run No.

Reactants, parts by weight:

'Irl-ethyl benzene 50 50 .50 50 52 52 51 50' Benzene 75 75 0 0 75 75 0 0 Hydrogen chloride 2 0 0 2 2 0 0 2 Initial pressure of- Hydrogen..atmospheres 100 100 100 100.... Nitrogen ..d0.. 100 100 100 100 Maximum pressure atmosphcres.. 215 248 208 202 200 282 250 245 Yield, per cent of theoretical based on tri-ethyl benzene charged:

Benzene 17 8 Ethyl benzene 34 18 9-5 34 0 l2 Dl-ethylbcnzene. 39! 51 as 29 41 4s 27 'lri-ethylbenzene... f 6 l8 14 50 50 30 Higherethylated bcnzcncs. i 2 4 13 ll 9 13 The results given in Table I show that it is beneficial to have benzene, hydrogen, and hydrogen chloride all present when de-alkylating tri- ,ethyl benzene in the presence of a zinc chloridealumina catalyst. v

EXAMPLE II ment was carried out under hydrogen pressure (run #3), 58% of the xylene was converted into toluene. In the absence of added benzene (run #2), 16% of toluene was formed at 400 C.

mm II De-methylation of xylene to toluene Bun No.

Reactants, parts by weight:

Xylene Benzencm... Hydrogen chloride Catalyst Temperature Maximum pressure. Toluene formed:

Partsbyweight 0. Per cent of theoretical based on xylene charged i The nature of the present invention and its commercial utility can be seen from the specification and examples given, although neither section is intended to limit its generally broad scope.

We claim as our invention:

1. A process for producting a substantial yield of a, mono-alkyl' aromatic hydrocarbon from a poly-alk'yl aromatic hydrocarbon which comprises subjecting said polyalkyl aromatic hydrocarbon, a non-alkylated aromatic hydrocarbon,

hydrogen and hydrogen chloride at a de-alkylating t mperature of from about 100 C. to about 500 C. to contact with a zinc chloride-containing catalyst.

2. A process for producing a substantial yield 01' a mono-alkyl aromatic hydrocarbon from a poly-alkyl aromatic hydrocarbon which comprises subjecting said poly-alkyl aromatic hydrocarbon, a non-alkylated aromatic hydrocarbon, hydrogen, and hydrogen chloride at a dealkylating temperature of from about C. to' about 500 C. to contact with a catalyst comprising essentially a composite of zinc chloride and an aluminum oxide-containing, carrier.

3. A process for producing a substantial yield of toluene from a poly-methylated benzene which comprises subjecting said poly-methylated benzene, benzene, hydrogen, and hydrogen chloride to contact at a temperature from about 300 to about 500 C. under a pressure of from substantially atmospheric to approximately 300 atmospheres in the presence of a catalyst comprising essentially a composite of zinc chloride and an aluminum oxide-containing carrier.

4. A process for producing a substantial yield of ethyl benzene from a poly-ethylated benzene which comprises subjecting said poly-ethylated benzene, benzene, hydrogen, and hydrogen chloride to contact at a temperature of from about 300 to about500 C. under a pressure of from substantially atmospheric to approximately 300 atmospheres in the presence of a catalyst comprising essentially a composite of zinc chloride and an aluminum oxide-containing carrier.

5. A process for producing a substantial yield of a mono-alkyl aromatic hydrocarbon in which the alkyl group contains more than two carbon atoms from a pol'y-alkyl aromatic hydrocarbon in which at least one of the alkyl groups contains more than two carbon atoms which comprises subjecting said poly-alkyl aromatic hydrocarbon, hydrogen, and hydrogen chloride to contact at a temperature from about 100 to about 400 C. under a pressure of from substantially atmospheric to approximately 300 atmospheres in the presence of a catalyst comprising essentially a composite of zinc chloride and an aluminum oxide-containing carrier.

6. A process for producing a substantial yield of toluene from a poly-methylated benzene which comprises subjecting said poly-methylated benzene, benzene, hydrogen, and hydrogen chloride to contact at a temperature from about 300 to about 500 C. under a pressure of from substantially atmospheric to approximately 300 atmospheres in the presence of a catalyst comprising essentially a composite of zinc chloride and alumina.

'7. A process for producing a substantial yield of ethyl benzene from a poly-ethylated benzene which comprises subjecting said poly-ethylated benzene, benzene, hydrogen, and hydrogen chloride to contact at a temperature of from about 300 to about 500 C. under a pressure of from substantially atmospheric to approximately 300 atmospheres in the presence of a catalyst comprising essentially a composite of zinc chloride and alumina. v

8. A process for producing a substantial yield of a 'mono-alkyl aromatic hydrocarbon in which the alkyl group contains more than two carbon atoms from a poly-alkyl aromatic hydrocarbon in which at least one of the alkyl groups contains more than two carbon atoms which comprises subjecting. said poly-alkyl aromatic hydrocarbon, hydrogen, and hydrogen chloride to contact at a temperature from about 100 to about 0C. under a'pressure of from substantially atmospheric-to approximately 300 atmospheres in the presence of a catalyst comprising essentialiy a. composite of zinc chloride and alumina.

'9. A process for producing a substantial yield of amono-alkyl aromatic hydrocarbon from a polyalkyl aromatic hydrocarbon which come prises subjecting said poly-alkyl aromatic hydrocarbon, a non-alkylated aromatic hydrocarbon, hydrogen and hydrogen chloride at a dealkylating temperature of from about 109 C. to about 500 C. to contact with a catalyst comprising essentially from about 5 to about 50% by weight of zinc chloride and from about 95 to about 50% by weight of alumina.

LOUIS SCI-IMERLING. VLADIMIR N. IBATIEFF.