US2370541A - Mineral oil cracking process - Google Patents

Description

Feb. 27, 1945. J. H. JAMES MINERAL OIL CRAGKING lROCESS Filed July 7, 1959 mmmIawOEP( OP INVENTOR ,alyst is used, it is preferably 'an oxide or com-- Patented Feb. 21, 1945 UNITED s'rArl-:s PATENT oFFIcE maaar. omcaacxmc mocass Joseph Hidy James, Pittsburgh, Pa., aaslgnor to Clarence P. Byrnes, Pittsburgh, Pa., an trustee Application July 7, 1939, Serial No. 283,209

z clam. (01.19642) y I above forty and occur- United States Patents 1,836,325 and 1,836,326v

partial oxidation methods wherein the oxygen tied into the hydrocarbon vapor is withdrawn from metallic oxides (termed oxidants) in a hot zone. These metal oxides may be the same as the catalysts used in that form oi my process 'where free oxygen is employed such as contained in air; or may be other metal oxides.

In either case, for cracking purposes, I preier' ably employ a mild oxidatibn, since any chemical tyingin of oxygen such as that sufficient to produce alcohols, greatly aids in cracking under low prescatalyst a silicate of a rare metal" such as molybdenum, vanadium, uranium, tungsten, etc.v Some of these may be prepared, for example, by

sures; and in both cases I preferably employ a plurality of cracking units connected to one or more units for partial oxidation; and when and if clogging of the cracking catalyst occurs I intermittently shift the' exit stream from the partial oxidation step, from one cracking unit to another cracking unit, and burn out the first one by admitting air or an air containing a. combustible. As soon as the rst unit is "burnt out" and the coatings of tar, carbon, etc., thus cleaned out, the stream from the oxidizing unit will be shifted back and cleaning out of the other ,and alternate cracking unit eiIected. l

The air or combustible mixture for burning out is preferably fed into the clogged cracking unit directly, or at" a point between the oxidizing and cracking unit and the stream of burnt gases is led from the cracking unit to the open air, suitable valve means being used to switch the exit having an atomic weight ring on the descending sides of the4 Lothar- Meyer `atomic volume curve. The main examples thereof whose oxides are catalytically active in oxidation are molybdenum, vanadium, tungsten, uranium, etc. Hereafter I shall term such metals rare metals".

In the cracking step, I prefer to employ a catalyst consisting preferably of hydrosilicates, an acid or non-alkaline silicate or clay, an earth metal, or zeolites; since I have Iound these t0 be especially efficient in the cracking of the oi'gen derivatives of hydrocarbon formed in the lpatrial oxidation step. s The cracking temperature is preferably in the range from about 300 C. to about 550" C.

I prefer especially to employ as a cracking adding a soluble salt oi the rare metal such as a chloride or sulphate thereof to 'a solution of sodium silicate. The rare metal silicate lwill be precipitated and should be separated and washed free irom'the sodium salts formed. Others require special methods oi preparation ofA their silicates. Such a cracking catalyst has certain advantages, since the catalytic properties of the silicates are combined with similar properties of the rare metals which act as activators.

I am aware that silicates or hydrosilicates have been proposed as cracking catalysts for straight hydrocarbons, but so far as I am aware, no one has discovered their peculiar advantages' in cracking a mixture of oxygen derivatives of aliphatic hydrocarbons in the range from alcohols to'oxygenated acids, which are'produced in the partial oxidation of aliphatic hydrocarbons such as petroleum or its fractions.

In the drawing where I show dlagrammaticallya system of apparatus for carrying out one form of my invention, 2 represents a vaporizer wherein the raw. fraction or crude oil may be vaporized and the heavy residue tapped out, and 2a the reaction chamber for partial oxidation of the mixture of vapor and air passing therein preferably in contact with a catalyst such as recited from 250 C. up to 600 C. preferably by employ- 50 ing a cooling uid, and any of the well known types of catalytic cells may be used. If` a catpound or complex or a low atomic volume high in my patents on partial oxidation. Leading therefrom are branch'pipes 3 and 3a controlled by reversing valve B pivoted'at I and tilted to close either conduit. Eachv conduit 3, 3a leads` to a cracking chamber ,gla, one o! which (shown as la) is connected to the oxidation chamber 2a and closed to-air supply pipe Il by valve Ila,

atomic weight polyvalent metal. especially those l5 while the other is closed tothe oxidation chamber and is regenerated by air or air and fuel fed through pipe 1 whose valve 1als open. From the cracking chambers extend branched pipes 8, 8a and 9,' 9a, respectively, controlled by reversing valves i0, a, of which 8 and 8a lead to condensers, dephlegrnators, orl bubble towers, while 9 and 9a open to the outer air.

In this form air and oil vapor pass throughl the oxidizer, the temperature of which is controlled within reactive limits, to tie free oxygen from the air into the hydrocarbon chains, preferably to a mild degree. Thence the mixture containing oxygen derivatives passes into one of the cracking units 4a where a cracking temperature is maintained and thence the cracked vapors pass to a condenser or bubble tower. During this stage unit 4 is being regenerated and burnt out, the exit stream passing into the open air. After a few minutes, for example, 6-10 minutes, the valves are reversed, the stream from the oxidizer is fed to the other cracking unit 4 and air is fed to` unit 4a. to burn out the coating collection on the cracking catalyst. When this burning out is completed, the valves are reversed.

In case the oxidant type of oxidation is carried out by withdrawing oxygen from an oxide' tion to remove a lower fraction boiling below the range of the fuel desired such as gasoline. The heavier portion may then be cracked, preferably in the vapor phase, with a cracking catalyst such as herein described; or if desired in the-liquid phase, or in both phases, with a catalyst.

One of the advantages of my process is that hydrogen is removed from the stock only in proportion to the oxygen chemically tied therein (except as to alcohol formation). Hence I can and do rerun the heavier portion remaining after gasoline removal following each run. In such case expensive high pressure cracking is not required for what is commonly called recycle stock as is the case where" excessive dehydrogenation takes place.

Under my broader claims which include regenerating or burning out of the cracking cataas in my Patents 1,836,325 or 1,836,326, the partial oxidation unit will have means for withdrawing the oxidant and for reoxidizing and returning it to the unit for reuse. Otherwise the apparatus may be like that of the figure herein, or the oxidant may, after reduction to a lower oxide, be revivied in place or otherwise by passing air over it while hot, to reoxidize it during the revivifying of the cracking catalyst. In this case, air would be fed over the oxidation catalystwhile air or air and fuel passes through the cracking catalyst, during the revivifying phase of each. This would mean in effect two lines of apparatus, one on one part of the cycle and the other on the other or revivi'fying part, and each connected both to the condenser or bubble tower and also direct to the atmosphere.

In case the cracking catalyst is carried into and out of the cracking zone or unit, the steps of oxidation and cracking may be carried out more continuously; and if the types of apparatus shown in my oxidant Patents Nos. 1,836,- 325 'and 1,836,326 of December 15,1931 are employed for the cracking catalyst, no reversal of periods need be used. If in such case the oxidant system of oxidation were also used, then both the oxidant and the cracking catalyst may be revivified as soon as used, by removal, treatment with oxygen or oxygen and fuel, and then by return to their chambers.

In all such systems heat may be supplied to the cracking unit during the cracking operation by external heat as desired; since the step here is endothermic while the oxidation step is exothermic. The layer of cracking catalyst may be .and preferably is thicker or deeper than that of theoxidation catalyst. The steps may be carried out under suction or under pressure above the atmosphere. If pressure is used, it need be only that sufficient to feed the mixture through the apparatus, since the oxidation step makes the cracking step easier and operative at lower pressures than now used; though higher pressures may be used.

In another form of my invention, the condensate from partial oxidation such as my vapor phase partial oxidation (preferably carried out in mild form) may be condensed and the condensate preferably fractionated as by distillalyst, I may use the same catalyst for cracking as I disclose in lmy patents for partial oxidation; such as molybdenum oxide, vanadium oxide, etc., mounted on any suitable carrier therefor such as various refractory materials including clays, silicates, etc.; or I may use rare metal compounds or complexes such as disclosed in my several pat.- ents herein recited.

The cracking catalyst may be changed, various carriers therefor may be used; oxygen may be tied in in the absence of a catalyst; any of the oxidizing catalysts of my patents such as Reissue 18,522 of September l5. 1936; 2,054,591 of September 15, 1936; 2,085,221 of June 29, 1937; or 1,739,620 of May 20, 1930 may be used and preferably those giving a mild oxidation to vapors of heavy fractions.

In another variation of my process, the cracking of the oxidation product is carried out in the vapor phase thereof and in the presence of hydrogen.

In such a process the oxidation product, preferably in the vapor phase, whether prepared by air oxidation or with an oxidant, is mixed with hydrogen and passed over catalysts, preferably consisting of my rare metal oxides such as vanadium oxide, molybdenum oxide, uranium oxide, tungsten oxide, etc.

By fthe term non alkaline in my claims I intend to include both acid and neutral agents.

The advantage of this phase of my invention lies in the fact that the use of hydrogen prevents the formation of too great an amount of heavy hydrocarbon Ior heavy hydrocarbon derivatives low in hydrogen and which cannot be recycled because of their low hydrogen content. This process would also aid in lengthening the time of passage prior to such clogging action as would require revivifying of the cracking catalyst.

I claim:

l. In the treatment of petroleum, the steps consisting of vaporizing la petroleum fraction f 2,910,541 a v 3 zmmethodottrcatingmineraloilconmainly straight chain saturated al1- phatic hydrocarbons. consisting of vaporizing the same. mixing it with a gas containing-free oxygen, partially'oxidizing the vapor-gas stream at elevated temperature in the presence of an oxidation catalyst containing a compound of a' low atomic' volumeQ high atomic weight4 polyvalent metal. and then thermally decomposing a material percentage of .thc hot vapor-gas stream in another sone and in the presence of a cracking catalyst containing naterial other than the said oxidation catalyst. A

JOSEPH HIDY JAMES.

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