US2273299A - Treatment of hydrocarbons - Google Patents

Description

Feb. 17, 1942. A.- szAYNA TREATMENT OF HYDROCARBONS Filed Oct. 8, 1938 INVENTOR Akvzmvznyww ATTORN EY Patented-Feb. 17, 1942 TREATMENT F HYDROCARBONS Antoni Szayna, Brooklyn, N. Y., assigner to Albert C. Travis, New York, N. Y.

Application October 8, 1938, Serial No. 233,983

(Cl. 19E-24) Claims.

This invention relates to a treatment of hydrocarbon, particularly those hydrocarbon oils which can be treated in. vapor phase, and to the use and re-use of special contact materials in said process. More particularly, the invention relates to a method of desulfurizing oils and controlling other concomitant reactions by a contact mass, the surface of which is adapted to absorb sulfur from sulfur compounds present in the`oil,.to a cyclic process in which the contact mass is periodically regenerated and reemployed in the process.

'I'he presence of sulfur or compounds of sulfur in petroleum coal tar and similar products has long been known, and its removal has long beenl recognized as a problem of great practical vimportance. In fact a large portion of the crude petroleum which is available at the present time is too high in sulfur content to be available for the production of high grade motor fuelwithout special desulfurizing treatment. One object of my invention is directed especially toward this problem; namely to provide a process for desulfurizing by which the value and quality of such sulfur bearing materials can be improved, although, as will be apparent from the following description, other advantages are attained by the novel treatment according to my invention which are not necessarily related to desulfurization.

Another object of the present invention is to desulfurze hydrocarbon oils, e. g., gasoline, while at the same time controlling other accompanying reactions toavoid deterioration of the product in other respects.

Another object of the invention is to produce a hydrocarbon product which is doctor sweet, non-corrosive, stable, of good color, and substantially free from tendency to form gums -upon storage.

Another object of the invention is to produce a motor fuel with improved properties, including improved lead susceptibility, low gum content and gum formation, high octance rating, etc.

Another object of my invention is to produce a motor fuel of such improved properties in high yield and substantially without objectionable byproducts. y

Another object of the invention is to provide a cyclic processwith regeneration of a contact material used in the process, and especially one in which any activity which it might otherwise have to deteriorate the product is largely inhibited in the regenerated material.

The invention comprises controlling the conditions, such as selection and treatment, including regeneration ofthe contact material, amount of contact material, velocity of iiow of oil, amount of hydrogen, pressure, temperature and the various other factors which influence the reactions, to obtain the desired sulfur absorption, selective hydrogenation, etc. v

A typical processaccording to my invention consists briefly, in vaporizing a high sulfur content gasoline and superheating the vapors, mixing them with a relatively small amount of hydrogen, and passing this mixture, advantageously under pressure, through a desulfurizing contactor of controlled activity, with the time of contact. depending upon the length of the contactor and the velocity of gas travel, sumcient to effect the required desulfurization. The treated vapors together with unconsumed hydrogen are treated for recovery of the finished-product and separation of the unused hydrogen, which may be recirculated in further operation of the process. After a period of such operation the sulfur absorbing contact material would become more or less saturated with sulfur to the extent that sulfur would begin to appear in the product as hydrogen sulfide. Since more than a trace of hydrogen sulfide in the liquid product is undesirable, I withdraw from the contactor, from time to time, before it is entirely saturated with sulfur,

, at least the most saturated portion of the contactor and replaceV or renew this portion so as to sustain the sulfur absorbing quality of the contactor as a whole.

The portion of the contactor which is withdrawn may be regenerated. in this typical process, by burning oil.' most of the sulfur therefrom, but leaving enough sulfur thereon to effect the desired chemical inhibition, and then reducing with hydrogen so far as to form a renewed contact material for reuse in the process.

Contactor I'have mentioned in thisprocess the contact material (which I sometimes refer to for convenience as the contactor) This is a material which chemically extracts and binds to itself the sulfur from the oil, including sulfur in hydrogen sulfide and in organic compounds, as well as any free sulfur which may be present. This contactor is in a physical form with extended surface such as would be adapted to act as a Asurface catalyst, and ordinarily its surface will be largely composed of a catalytically active metal, but its activities are so controlled as to avoid undesirable catalysis which otherwise would deteriorate the product during the contact and at the temperatures necessary for the desired eiiicient desulfurization.

I have found nickel to be the most advanta-` geous metal to use for the contact surface; but I have found that nickel alone, e. g., in the form of metal wool or chips tends to become brittle and to disintegrate in the course of regeneration; I, therefore, prefer to utilize a nickel surface on a porous inert carrier of good mechanical strength and other properties. Such carriers are already well known in the art of catalysis;

among them I may mention as particularly suitable for my reaction, pumice, bauxite, unglazed porcelain, kieselguhr, silica gel, porous carborundum. To these may be added small amounts of difilcultly reducible oxides, e. g., oxides of aluminum, chromium, thorium, magnesium, and/or materials for strengthening the carrier, e. g., small amounts of alkali metal compound such as sodium hydroxide or carbonate, when a silicious carrier is used, or water glass, when a non-silicious carrier is used. Materials which also act as catalysts may be used where the reactions which they favor are desired. Active clays will ordinarily be avoided, unless it is desired to catalyze polymerization.

' Inhibitor I may utilize various methods of controlling catalytic activity, in order to inhibit to the desired extent, according to my invention, the undesired reactions, while keeping the surface of the contactor in a form to give rapid and efflcient reaction with the sulfur in the flow of gases or vapors to which it is exposed.

The method which, in general, I have found to be most satisfactory is the addition to the contactor of a chemical inhibiting agent, such as a catalytic poison, which may be relied upon to reduce the catalytic activities without a corresponding reduction of the desulfurizing activity; and thus with the inhibited material a much greater desulfurization can be effected without serious deterioration of the product by catalytic reactions. It is. important to have this inhibition effective all over the bed of the contact material, i. e., without zones which are fully active.

The control of the activity of the contact material may at the same time reduce its capacity as a desulfurizing agent; but, because the catalytic activities are decreased proportionally much more, the actual desulfurization by my process is more complete, rapid and eiiicient than -by use of highly active catalytic desulfurizing materials, as is made more clear below.

Although, according to my invention, the catalytic activities of the contact mass are intentionally inhibited, e. g., by poisoning, they need not be completely destroyed. It is an important advantage of my invention that it provides a control for catalysis of high temperature reactions in an oil by which a limited and selective hydrogenation and/or dehydrogenation may be utilized to improve the quality of the product as well as to facilitate the desulfurization. This limited and selective hydrogenation activity is retained, according to my invention, while the harmful phenomenon of decomposing hydrocarbons into the elements, hydrogen and carbon, is inhibited entirely or to the point of insignificance, even well above 650 F.

The chemical inhibitor which vI have found most satisfactory and most advantageous is the very sulfur which it is the purpose of the contact material to remove from the oil. Other materials which have an inhibiting effect such as chlorine, bromine, iodine, selenium and/or tellurium may be used in small amounts with a somewhat similar effect. The criterion of value of such inhibitors for use in my invention is in the difference in the degree to which they depress or suppress undesired reactions disproportionately more than the desulfurizing activity or capacity. These inhibiting materials may be retained, at least partially, on the catalytic mass during and throughout its regeneration; and insofar as they may be eliminated they are inexpensive to replace. Mercury and lead, and in general any metal which forms an alloy with the contactor, will reduce the catalytic activity; such metals, however, tend to reduce the desulfurizing activity more strongly and are, -therefore,less ,desirable than the inhibitors previously mentioned above.

A most advantageous process according to my invention is one in which sulfur is used as the inhibitor; and the contact material, when it has become more or less saturated with sulfur, is not regenerated to a fully active catalyst, but instead is regenerated by a. treatment controlled to leave a sufficient amount of sulfur in all parts of the regenerated mass to still inhibit the catalytic activites when the regenerated contacter is again put into service.

The amount of sulfur or other inhibiting agent,

is not sharply critical. Withincreasing small amounts of sulfur distributed in the contact surface, the catalytic activity of the contacter is rapidly decreased while the desulfurizing activity decreases only very. little. Later. as the surface approaches saturation with sulfur, the desulfurizing activity drops more rapidly while the catalytic activity decreases very little more. This differential is utilized according to my invention by operating between a minimum sulfur content, at which the catalytic activity, especially for decomposition, is already substantially below that of the pure metal, and a maximum content, at which hydrogen sulde would begin to form. It is important in this process that no substantial part of the contact mass contain less than said minimum sulfur content during its use in the high temperature sulfur absorbing treatment. In practice, however, parts of the contactor may be allowed to reach or exceed the maximum so long as subsequently contacted parts of the mass are well below the maximum so as to remove any hydrogen sulfide which might be formed in the sulfur saturated zone of the contactor.

The amount of sulfur necessary to produce the inhibition which will protect the product against deterioration will depend very much upon the uniformity of distribution of the inhibiting agent in the contact surface, and upon the depth of the sulphur absorbing metal below the exposed surfaces. With a contacter such as is described below in the preferred embodiment, I havefound that a most economical effect occurs with ay sulfur content in the neighborhood of 15%, based on the weight of the nickel, but if the sulfur is uniformly distributed an amount as low as 5% or even 3% will give substantial protection. Preferably the sulfur content should be reduced to, at the least, vabout 20% at each regeneration. With heavier coating of nickel on the carrier or especially if nickel is used without inert carrier the percentages of sulfur would be lower, since it is primarily the surface which is concerned in this process. f

Within the general limits specified, the precise extent to which sulfur is present in the contactor when its use is begun will ordinarily depend upon cost considerations. Since the uniformity of sulfur distribution becomes more important as the minimum sulfur content is approached, the cost of precautions necessary to assure uniformity will oset to some extent the savings which would otherwise result from longer operating periods made possible by lesser sulfur retention.

Regeneration with sulfur retention If air by which the sulfur is burned from the aar-3,299

contactor is passedmrougnltne contacteren tinuously from one side thereof toward'tl'ieotlierbe completely deprived of its sulfur, while the. part near the exit oi the gases may still retain a.

substantial part of its sulfur. If such a contactor were put into use in a high temperature desulfurizing treatment, such as is described below, the sulfur-free part of the catalyst would produce objectionable reactions, e. g.. of decomposition into hydrogen and carbon and excessive hydrogenation.

In my preferred process, I assurethe retention of the necessary small amounts of sulfur throughout the contactor, by the simple step of removal of the sulfur from the contactor under carefully regulated conditions, especially of heat dissipation, such that the reaction can proceed as a self-sustaining reaction atl the given temperature only so long as the concentration of sulfur remains above that desired in the regenerated contactor. Thus, as soon as anypart of the contactor has its sulfur concentration reduced to the desired extent, the heat balance at its surface will be such as to terminate the reaction; and a residuum of poisoning sulfur will be retained upon that part of the contactor regardless of how long it may be necessary to continue the passage of air and/or other oxidizing gas through the contactor for burning excess sulfur from other parts thereof.

It is important, moreover, that during this treatment the temperature of the contact surface should not be allowed to increase excessively and that the temperature should advantageously be kept below about 1000 F. as measured by a thermocouple embedded in the contactor. Above about 1000 F. the physical or chemical condition of the nickel or other sulfur absorbing material at the surface may be altered so that it is less active for desulfurization.

Both the control of sulfur retention and the control of maximum temperature, I have found can be most effectively secured by supplying to the contactor a regulated mixture of air and steam at temperatures substantially below that at which the reaction with sulfur of the contactor mass would occur and continue spontaneously after the sulfur is reduced to the concentration in which it is to be retained for the purpose of inhibition. The temperature of these gases ordinarily should be Well below 600 F.; and in practice I find it advantageous to supply air at room temperature mixed with steam at a temperature as low as is practicable while avoiding undesirable condensation, e. g., about Y250 F. The use of steam I have found to have great advantage over any other gases known to me; and, although the nature of its action has not been conclusively determined, I believe that the reason is that the steam serves both as a chemical cooling agent and as an oxygen containing agent for conversion of the suliide to the oxide, and perhaps has an action also as a catalyst or promoter-at least it causes the reaction to proceed more rapidly at the relatively low temperatures used.

The reaction by which the oxygen of the air reacts with the sulfide, with formation of the metal oxide and sulfur dioxide, is an exothermic one-that is to say, it releases large amounts of heat-and since this release of heat is concentrated on the thin surface layer, the physical condition of which is most important to the ling local overheating is a vpeculiarly diicult one.

On the' otherlhand, the .reaction by which the Y. water vapor transfers its-oxygen tothe metal,

of the sulde and removes the sulfur ashydrogen sulfide is'an endothermic reaction-that is e to say, it can proceed only if heat or equivalent energy is supplied from the outside. \In the process according to my invention'this latter reaction also proceeds directlyupon the surface of the contactor; and since this surface tends to adsorb the water vapor, it will proceed whenever the necessary energy is available. Thus, according to my invention, the presence of the water on the surface serves as an automatic control for the temperature of the surface: as soon as the direct oxidizing reaction with air makes energy available, which ordinarily would be released in the form of objectionable heat, the water on the contactor surface, according to my invention, immediately utilizes that energy in its endothermic reaction, so that this energy may be transferred and consumed directly as chemical energy without any serious danger of overheating the surface of the contactor.

The hydrogen sulde formed in this reaction is, of course, a combustible gas, and to some extent atleast it may burn in the excess air or react `with SO: with further release of heat. I have found, however, that the heat thus released in the gases is relatively harmless, being largely carried ofi' with the exhaust gases, and only being slowly transferred, if at all, to the contactor surfaces, whereas heat released in reactions occurring on the contactor surface may easily overheat and damage thats surface. Any excess steam will serve by dilution to slow down such burning of hydrogen'sulflde.

The action of the steam thus serves to keep the temperatures of the contactor in a range near the lower limit at which the reaction with air proceeds spontaneously, and consequently, as soon as the concentration of the sulfur on the surface is suitably reduced there will at first be less and less energy'available forthe reaction with water; and finally, the rate of heat generation in the reaction will fall below the rate of heat dissipation from the contactor surface, after which the surface will soon be cooled below the temperature limit at which the reaction ceases, and the residual sulfur will-remain in the contactor surface to serve as a catalysis inhibitor notwithstanding that the passage of air and steam is continued for the burning of other portions of the contactor surface which at rst were receiving mostly the sulfur bearing gases from the preceding parts of the contactorand had had as yet no chance to react.

It is possible to effect a similar but less perfect control by diluting the oxygen vwith inert gases. This method of control, however, will involve a longer reaction time. It is possible to attain sufficient uniformity of sulfur retention merely by controlling the flow of the regenerating gases, especially by reversing the ow or changing its course as certain parts of the contactor approach a given sulfur content. If adequate distribution is maintained, the sulfur content may be controlled merely by stopping the regeneration at the proper moment.

The process of preparation andregeneration of the contactor with control of sulfur removal, and especially by temperature control through control of chemical reactions, is claimed in a activity of the contactor, the problem of controlcompanion application Serial No. 117,673, filed December 24, 1936. Y

The product of the oxidation treatmentis reduced with hydrogen, and this should occurv at a moderate temperature to avoid reduction of desulfurizing activity. I prefer to carry this out between 600 and 800 F.

Another important feature which is made possible by my invention is the close temperature maintenance throughout the cyclic process whereby the contact mass, substantially throughout its use and regeneration is maintained within a temperature range of, at most, a very few hundred degrees. I have found that in this way the output of the apparatus required can be very greatly increased and that the activity of the contactor can also be maintained over a much longer useful life.

Temperature of oil treatment 'I'he use of relatively high temperatures during the desulfurization of the gasoline is another important feature of my invention; and when such high temperatures are used the control of catalytic activity, according to my invention, is especially important. 'I'he use of such high temperatures will greatly increase the rapidity of desulfurization and the efficiency of utilization of the contactor so that with a given amount of contactor a much larger volume of hydrocarbon oil can be treated and more sulfur can be ab-v sorbed from the oil by a given amount of the contactor. i

I have found also that a number of the more refractory sulfur compounds which occur in the hydrocarbon oils may be readily and substantially completely removed by my contactor at temperatures above 700 F. and especially above 750 F., without the occurrence of other undesirable reactions which might be expected at such temperatures in the presence of a surface active contactor.

The most serious reaction which comes into prominence at these higher temperatures in the presence of the ordinary highly active catalyts is that of decomposition of hydrocarbons into the elements carbon and hydrogen. Although this decomposition is often overlooked or confused with cracking, it is quite a different phenomenon, and one which needs to be carefully avoided. It is bad, not merely because of the waste of those hydrocarbons which would be destroyed by the decomposition, but also, and even more important, because of the fact that products of the decomposition would be deposited upon and blanket the surface of the contact material so as to seriously impair or even to destroy its ability to perform effectively further desulfurization of the oil.

The metals nickel, cobalt and iron which are mostJdesirable for use in the desulfurizing contactor are also most active in catalyzing this decomposition reaction at temperatures above about 600 F.

Such reactions as cracking, polymerization, hydrogenation and dehydrogenation' may, of course, proceed to some extent at these temperatures, and more rapidly with increasing temperatures, even in the absence of catalysts; and these reactions may even be stimulated to some extent by the contactor used in my invention. It is in fact an important advantage of `my process that, by use of the inhibited catalyst, such reactions may be promoted selectively and limited as desired. Thus,'for example, one may have selective hydrogenation of objectionable, e. g., gum forming, constituents and of the carbon linkages released by sulfur removal, substantially without hydrogenation of desirable, e. g., aromatic, hydrocarbons. Operating conditions may be chosen to favor desired products in accordance with well understood laws of chemical reaction. Thus, an increase in the amount of hydrogen present with the hydrocarbons during treatment or an increase in pressure with sufiicient hydrogen will tend to increase hydrogenation. A high temperature without added hydrogen or with very little hydrogen favors dehydrogenation and polymerization. Lower pressure favors simple dehydrogenation, whereas higher pressure favors polymerization. The conditions of high temperature and low pressure will bring into prominence the reactions of dehydrogenation over those of hydrogenation. In the temperature range above 850 F. the cracking reactions are strongly favored by temperature increase.

Hydrogen The use of hydrogen is important in my invention though not entirely essential. Without hydrogen or with too little the product may be to some degree unstable, of high gum content and subject to serious polymerization; and moreover, the desulfurization will proceed more slowly and in many cases will be less complete if hydrogen is not added. The presence of hydrogen apparently serves, as already described above, to satisfy the carbon linkages in the compounds from which the sulfur is removed, and thus at once to facilitate the desulfurizlng reaction and to avoid the formation of unstable unsaturated products.

At higher temperatures such that considerable cracking occurs more hydrogen will be consumed, and unless a highly unsaturated product is desired, more hydrogen should be supplied. (Such cracking in the presence of my novel contactor is more particularly described and claimed in' my companion application Serial No. 231,298. filed September 23, 1938.) 'Ihe amount of hydrogen used is not sharply critical, but depends upon the raw stock being treated` and the products desired. In general, straight run and highly paraflinic oils require less hydrogen than cracked or other highly unsaturated oils; and treatment during which cracking or reforming is combined with the desulfurizing will require more hydro- Een.

When treating oils for Diesel fuels by my process a relatively high concentration of hydrogen is favorable.

-I have found that the use of a large excess of hydrogen tends to stimulate hydrogenation reactions which are undesirable in treating gasoline, and which cause an uneconomic consumption of hydrogen in such treatment, but which may be desirable, e. g., for Diesel fuel. Such excess of hydrogen tends also to form hydrogen sulfide with' high sulfur stocks, even with a contactor which is still capable of satisfactory use with a more suitable proportion of hydrogen. Ordinarily, for the average high sulfur raw stock, an addition of 1% of hydrogen, based upon the weight of the oil mixed therewith during the treatment, will be adequate, and in general the amount of hydrogen introduced with the raw stock will be increased with increase of the amount of sulfur which `is required to be removed. e. c.. 0.25% to 2.0% of hydrogen. but even serious objection.

Even when an adequate amount of hydrogen is used there may occur simultaneously both hydrogenation of undesirable and gum forming 2,273,299 ve times this amount may be used without net consumption, i. e., the difference between the amount supplied and the amount remaining after the treatment. v-

The hydrogen used need not be of high purity.

Specific examples In .the accompanying drawing I Ahave shown also a. diagrammatic arrangement of apparatusV serving also as a process ow sheet, illustrating a preferred embodiment of my invention. It should be understood that the drawing and the description given herewith and the various alternative structures and procedures suggested herein are not intended to be exhaustive nor limiting of the invention, but on the contrary, are chosen for purposes of illustration and explanation in order that others skilled in the art may so fully understand the invention and the principles thereof and the manner in which itis applied in practice that they'will be able to vary and modify it in numerousways and toembody` it in numerous forms each as may be best suited to the conditions and requirements of a particular use.

Referring to the drawing, the raw stock is supplied through' the pipe line I0, the pump II, the

heat exchangers I3 and I4, and the tube heater and still I6. 'Ihe hydrogen, either from the supply line I1 `or from the recirculating tank I8 isv compressed to pressure required in the system by the compressor I9 and then passed into the raw stock supply line, where it is mixed with the raw stock and with it passed through-the heat exchangers I3 and I4 and into the tube heater I6.

The mixture of raw stock and hydrogen passes from the tube heater through the plp`e20 into one of the three reaction chambers 2I A, B or C. These reaction chambers are substantially identical, and each is lled with a contact mass which may consist in this preferred example of a pumice carrier, e. g., in pieces averaging about Vs v.to 1/2' inch in diameter. A pumice stone having about 0.38 apparent speciiic gravity is suitable for this purpose, but the numerous other carriers already known in catalytic work may be used likewise. The pumice grains are impregnated to 'cover the surfaces with nickel to the extent of about 10% of nickel based on the total weight of the contact mass; andabout 1% of aluminum oxide may be added. The aluminum oxide helps to preventrecrystallization of the nickel during regeneration', which would reduce th'e sulfur absorbing surface, and permits higher regeneration temperatures. It also absorbs water so as to supply it locally during regeneration to offset the exothermic effect o! the regeneration reaction. The nickel and aluminum vmay be applied to .the pumice as sulfate solution which is subsequently precipitated, e. g., with sodium carbonate, and/or dried, or as fused salts, e. g., fusednitrates; in either case the deposited salts may be roasted carefully to the oxides and the nickel oxide reduced to metallic nickel at a temperature low enough to assure high surface activity, e. g., below 650 F.

" The contact mass should be suitably 'treated for inhibition of catalytic activity beforeregulari use. Thiscould be done, e. g., by passing gases or ol containinghydrogen sulfide mass. v

'Ihe contact chambers 2| are connected to the supply line 20 by valved branch pipes 22; and a manifold 24 is provided for connecting the top of any chamber with the bottom of any other chamber through the valved connections 23 and 25 re-y spectively. Any of th'e chambers A. Bor C may be'connected through'the valved connections 26 to an off-take manifold 21. From the off-take manifold 21 the treated vapors pass to a suitable oil separating and recovery system.-

. As one example of the use of this apparatus for the process of my invention, I have taken as raw stock a naphtha from a high sulfur Mexican crude. This naphtha contained about 0.67% sulfur, had a boiling range from about F. to 450 F.` This raw stock was fed intoy the system by the pump II. Hydrogenat a rate slightly below 1% (by weight) that of the raw stock was supplied by the compressor I9. The `pressure was maintained inthe system land especially in the reaction chambers about 200 lbs. per square inch.

The mixture was preheated to a temperature of about 830 F. by the heat exchangers I3and I4 and the tube heater IB. Assuming that the reaction chambers Av and B are operating in series, 'and C is being regenerated, the valved connection 22 to the reaction chamber -A will bel open and the corresponding connections 22 to the chambers B and C will be closed. Likewise,-

and hydrogen passes into-the top of the cham,

ber A and through the contactor therein, which will be ata temperature a little above 800 F., and out through the connection 23 and the manifold 24 into the connection 25 of the chamber B and thus into the top of the second reaction chamber B,- from which the treated product passes oi'f through 26 Iand 2l for cooling, separation and further treatment.

The rate of flow is regulated to give a contact period in the two chambers A and B sufficient to effect the desired desulfurization.

In the reaction chamber A the vapors have encountered a contactor relatively high in sulfur content. In the chamber B the vapors encounter the most recently regenerated contactor and one, therefore, which although inhibited by its retained sulfur content, is more active as a desulfurizing agent. Thus, when the vapors have passed through the second chamber B the desired chemical treatment is completed.

By suitable insulation of the reaction chambers and connections the heat of the vapors is conserved and no other heating is required. However, if less insulation is used or if the fresh or freshly regenerated contactor in the second reaction chamber is at lower temperature when first put into service, the temperature in a part or all of the second chamber may be much lower. There is no objection to this except that the effectiveness ofthe cooler contact massr is reduced.

The vapors which leave the reaction chamber B through the connection 26 and 21 are comthrough the This is accomplished in the present case by passing the efiluent from 'the reaction chambers through a heat exchanger 2l and a water cooler 20 into the gas separator and scrubber 30 where condensible and soluble hydrocarbons are re- Y moved from residual hydrogen and the residual hydrogen bled ofi and collected in the tank Il for recycling in the process.

With such recycling, in the particular example mentioned. about 0.18% of hydrogen (based on the weight of the oil) is consumed. including losses in the operation and must be supplied from outside sources when residual hydrogen is recycled.

The oil passing from the gas separator and scrubber 30 is again heated by the heat-exchanger 28 and passes from thence with reduction oi' pressure by the valve 32 into the fractlonating tower 35 where any heavier hydrocarbons are separated and collected in the bottom of the fractionating column, from which they are recirculated by a pump 33 to the scrubber Il, passing rst through the heat exchanger Il and the water cooled heat-exchanger 3|. Il there should be an excess of bottoms it may be drawn of! to storage through the line 36.

A steam heating coil 31 may be provided in the bottom of the fractionating column for indirect heating, and live steam may be supplied through the pipe 38.

The desired product comes from the fractionating column 35, passes through the heat exchanger I3, where it serves to preheat the raw stock and hydrogen, and advantageously through a final cooler 39 and a pressure release valve Il to a gas separator and receiver 40 and iinally into a gasoline storage tank (not shown). Tail gases and water separated from the gasoline are drawn of! from the separator 40 through the connections shown.

The following comparison of the same stock used in the example just described. i. e., naphtha from high sulfur Mexican crude, treated by ordinary methods and by my process as just described will illustrate the advantage of my process:

Raw stock My product lo n. m M

acid/bbl. acid/bbl Chemical treat- No treat- Vapor phase Acidcaus- Acid causment. me c o n t a c t tic doctor tic doctor.

described Treatment loss.. l2.7%. 12.2%. Gravity .1.. 49.1. Color (Saybolt). +28. t lw' ur Gum (AsTM) 0.4 mi--- 0.a m. Initial boiling 172 2m".

point. 7 228 244 w". so :414 320. 90% 380 379 390. End point 438 442.

The sample of my product tested was a composite blend of ten samples taken at equal intervals during the entire period of operation of one pair of reaction chambers until one was ready for regeneration.

'I'h'efadvantage as to octane rating and lead susceptibility is shown by tests made on Metallic nickel-- 2.5%

of these same products with casing head gasoline:

The iniluence of the temperature is shown below in a series of experiments with separate samples of the same California cracked distillate using the same contactor as was used with the Mexican naphtha above referred to. 'Ihe amount of nickel was 2.5% based on the oil, and 1.06% hydrogen was introduced, the time of reaction being about 12 minutes in each case:

Temperature, F.

Rswsroek 000 100 820 Yield by weighs pernz.. oas 98.0 08.8 GravityA.P.I.at00.....degrccs.. 49.7 50.5 51.1 51.9 sulfur .pernr.. 0.65 0.31 0.19 v0.01

The iniluence of the amount of contactor relative to the oil is shown below in a series of experiments in a batch operation with the same raw stock; the amount of hydrogen introduced and time of contact being as shown above, and the temperature of reaction being about 820 F.:

1.4% Raw stock Sulfur 0.07% 0.19% 0.66%

Another example follows in which cracked California heavy naphtha was treated at high temperature in the reaction chambers for production of low sulfur gasoline:

condition of treatment t The analysis of these stocks is given below:

Raw stock Finished gaso- VSemiprodue't une n Co per-dish gum. In tial boiling point. Endboillngpoint. Octane No The lead susceptibility of this product (like au products'resulting from my process) was greatly blends 7s improved as compared with that of the raw stock.

' ejer/3,299

No acid treatment is necessary in my process' unless the raw stock treated has nitrogen bases or phenols. These compounds are only partly attacked by the desulfurization treatment according. to my invention, and for their complete elimination a small amount of diluted acid, e. g., 80% strength may be used and followed by a caustic wash. a

The chemical treatment of the semi-product in the example just given requires that the oil from the separator 30 should be drawn oi! to the treating tanks (not shown) before passing on to the fractonator 35. It is also advisable in this case to use a separate scrubber for the gases from the separator, becausethese gases contain a much larger proportion of hydrocarbon gases as a result of the cracking and require. therefore, a larger amount of scrubbing oil which it is not desirable to mix with the condensed product. Instead of the oil scrubber, active charcoal can be used.

Two additional examples are given below in parallel columns:

Treatment of contact material R ene-.ration medium Air and steam air and steam Rglgzeneration temperaturem.. 70800 F. 7008l0 F. Reduction medium Hydrogen Hylglmgteyn of 85% Reduction temperature 450-800 F. 400- F.

` California late Raw stock:

Gravity A. P. I. at F Color :sa ot corrosive. 390 F.

0.0l o Not corrosive--. 427 F End Aromatics in both cases remained unchanged within limits oi analytical error.

As anv example of heavier raw stockpMexlcan (Panuco Field) kerosene was treated under con.v

ditions similar to those described in the rst example with Mexican naphtha, but at somewhatv lower temperatures (730-8l0 FJ. 0.21% by weight hydrogen was'consumed. Results are giveny below: i

Raw stock` My process sa Ilia 0K a 51 o. om

All other tests (including burning tests) classed my product as premium kerosene.

The raw stock ordinarily need not be distilled and fractionated before the desulfurization treatment; but such treatment is advisable with weathered and a'sphaltic oils in order to remove gummy and tarry constituents which might deposit on the contactor and impair furizing ability.

If more sulfur can be tolerated it may be more economical to operate with more rapid flow, or

shorter path of travel through the contactor or with less hydrogen.

During the desulfurizing operation the third reaction chamber C may be undergoing a process of regeneration. Assuming that the reaction chamber C has previously been utilized in the desulfurizing series and has just been segregated from the flow of vapors, itscontact mass will be at a temperature inthe neighborhood of `800 F., and its reaction mass will be largely converted to sulfide.

As apreliminary` to the regeneration it is ordinarily desirable to clean out thel reaction cham ber by closing the valved connections 22, 23, 26

this cleaning treatment may pass off with the waste gases through the valved connection 4 1, the manifold 45, and condenser 49, to the separator 50 designed to separate the hydrocarbons from the condensed water. Since these hydrocarbons contain hydrogen sulfide formed by action of the steam on the contactor they are not mixed with the treated product, but they may be mixed with the raw stock if desired.

As soon. as the hydrocarbons and any other vaporizable materials are sufliciently cleaned. out of the reaction chamber the exhaust is diverted through the outlet 45'. At the same time the steam flow through the valved connection 43 i-s decreased and at the same time air is blown in from the air line 42 through the manifold 44 vand the valved connection 46. Since at this stage the contact mass within the chamber C is still at a temperature at`which energetic oxidation of the sulde (which I sometimes refer to as combustion) occurs spontaneously, such reaction f will begin to take place at once. By a suitable control ofthe proportion of steam supplied from the line 43 the temperature within the reaction chamber C may be suitably controlled.

More steam than air is ordinarily to be used at the start and less steam or even air alone may be used near the end of this regenerating step. l

If the steam and air are properly proportioned, the reaction will terminate automatically as soon as the desired degree of desulfurizationhas occurred. As soon as the temperature drops, e. g.,' to about 650 F., the oxidation treatment may be considered completed for my purpose. The temperature in some zones may drop considerably lower, e. g., to about 500 F. or lower and this condition can be improved by reversing the flow of steam, and/or air or hydrogen or other gas used during regeneration: and also this part of the mass may be heated by the oil through the connection 6i, and the ow of hydrogen thus continued until the desired reduction is attained.

It is not essential that the reduction in this its 'aesinstage should be complete, and in fact the oxidized material may be reduced by turning the flow of hydrocarbon vapors and hydrogen directly into the oxidized contact mass. '1111s latter procedure, however, is not recommended, since it consumes hydrogen which should be available for reaction with the oil; and if it is adopted a much larger amount of hydrogen should be supplied to care for the reduction of the oxide. Even with this additional hydrogen, however, the oxide may cause a temporary deficiency of hydrogen in parts of the vapors so that the results may be unsatisfactory with respect to polymerization, stability and gums. It is for this reason especially that the reduction is recommended.

When the desired reduction has been effected the reaction chamber C is ready for use in the process; and it may, therefore, be cut into the series once more by closing its valved connections 46 and 41 and opening the valved connections 25 and 26. At the same time the chamber B will be changed from the second in series to the first in series by closing its valved vconnections 25 and 26 and opening its valved connections 22 and 23, and the reaction chamber A will then be segregated from the ow of vapors by closing its valved connections 22 and 23 and its contact mass regenerated as already described in connection with the chamber C.

Thus, each chamber in turn when regenerated serves first as the second chamber of the series, then as the ilrst chamber of the series and during a third period is segregated from the ow of vapors and its contact mass regenerated; while the flow of vapors-i treated continuously in an initial contacter which is partially exhausted, and finally in a freshly regenerated but at least partially inhibited contacter.

During the period of treating the oil the heating of the contact mass is assured by the hot vapors coming from the pipe still until at the end of this period the contact mass is above about 800 F, sometimes even considerably higher, e. g. 950 F.

During the steaming out treatment the temperature drops somewhat lower, but with the admission oi' air a further heating occurs which is controlled by the regulated addition of steam to carry the temperature up to about 900 F.

Upon termination of the reaction, the air and steam lower the temperature of the mass again, e. g., to a temperature of about 700 F.; and during the reduction treatment the temperature ordinarily is not very greatly changed.

The pressure chosen may be maintained throughout the desulfurizing operation without change, the burning of the sulfide may with advantage be at atmospheric pressure, and in that case the pressure may be gradually brought back to the operating pressure by the hydrogen used during the reducing step.

Although I have used for these examples pressures of 200 lbs. and 500 lbs. per square inch and I have found pressures from 1D0-1000 lbs. per square inch most suitable for the treatment of these particular oils; nevertheless, a widel range of pressure is permissible without departing from my invention.

Although I have shown in eachof my examples, three reaction chambers, it will be understood, of course, that the number will be determined primarily by engineering considerations. The ilow of gases in the chambers may, of course, be upward or downward.

Hydrogen, which in the example is added to the liquid oil, may with some advantages be added to the vapors, e. g., in the line 20, or at other point or points in the line ofiiow.

Although I have speciiied in each of the examples the regeneration of the contact mass by treatment with air and steam and subsequent reduction with hydrogen, my invention is not limited to this particular type oi treatment and in general I may use any of the methods available for regenerating catalysts provided that they are controlled to retain a small amount of poisoning, or that the regenerated contacter is otherwise treated to control its catalytic activity.

These various alternatives have been mentioned to illustrate the numerous variations which can be made without departing" from the scope of my invention, and it will be understood that these are only a few of the variations which are possible. Y

Thisapplicationisacontinuationinpart of the prior copending applications Serial Nos. 231,298, filed September 23, 1938; 117,673, filed December 24, 1936; 94,578, led August 6, 1936; and 60,466, filed January 23, 1936.

What I claim is:

1. A process of desulfurizing sulfur-bearing hydrocarbon oils which comprises passing such oil thru 1a porous contact mass having an extended surface comprising free metal of the class consisting of nickel, cobalt and iron, and having sulfur distributed substantially throughogt said surface acting as an inhibitor of its catalytic a'ctivity, segregating at least a part of said mass from the oil flow after it has taken up a substantial amount of additional sulfur from the oil, removing such additional sulfur by oxidization at temperature sufiiciently low to avoid substantial impairment of desulfurizing activity, terminating the oxidation reaction in each part of the mass while sufficient sulfur remains in said mass to substantially poison its catalytic activity, substantially reducing the oxide formed in the oxidation step, and again in a repetition of the process utilizing the contact mass thus reformed.

2. A process of desulfurizing sulfur-bearing hydrocarbon oils'which comprises passing such oil thru a porous contact mass having an extended surface of a metal of the class consisting of nickel, cobalt and iron, which contact mass contains at least about 15% of sulfur, based on the weight of said metal, segregating at least a part of said mass from the oil flow after it has taken up a substantial amount of additional sulfur from the oil, removing such additional sulfur by oxidization at a temperature sumciently low to avoid substantial impairment of desulfurizing activity, terminating the oxidation reaction while at least about 15% of sulfur based on the weight of said metal remains in said mass to substantially poison its catalytic activity,

, reducing the oxide formed in the oxidation step while substantially retaining said sulfur, and again utilizing in a repetition of the process the contact mass thus reformed.

3. A process of desulfurizing sulfur-bearing hydrocarbon oils which comprises passing such oil thru a porous contact mass having an extended surface of a metal of the class consisting of nickel, cobalt and iron, which contact mass contains at least about 5% of sulfur based on the weight of said metal distributed throughout substantially all parts of the mass, segregating at least a part of said mass from the oil flow after it has taken up a substantial amount of additional sulfur from the cil, removing such additional sulfur by oxidization at a temperature suillciently low to avoid substantial impairment of desulfurizing activity, terminating the oxidation reaction while at least about of sulfur based on the weight of said metal remains in everypartofsaidmstosuhstantiallypoison its catalytic activity, reducing the oxide formed in the oxidation step while retaining sulfur therein, and againutilizing. the contact mass sulfur by oxidization at a temperature sum-- ciently low to avoid substantial impairment of desuifurizing activity, terminating the oxidation reaction while at least about 3% oi' sulfur based on the weight of said metal remains in said mass to substantially poison its catalytic activity, reducing the oxide formed in the oxidation step but retaining at least about 3% sulfur base on the weight of said metal, and again utilizing the contact mass thus reformed in `a repetition of the process.

5. A process of desulfurizing sulfur-bearing hydrocarbon oils which comprises vaporizing such oil and superheating its vapors, passing said vapors through a porous vmass of contact material having an extended surface of a metal of the class consisting of nickel, cobalt and iron and having an inhibitor distributed substantially throughout said surface, continuing such passage until at least a part ci' the contact mass is substantially converted to sulfide by sulfur taken up from the oil, segregating from the oil at least a part of the contact mass which has been thus converted to sulde, passing through the contact mass an oxygen-containing gas adapted to ccnvert said sulilde to oxide, passing through said mass a reducing gas adapted to reduce said oxide to the metal, and again utilizing the reduced mass for desulfurizaticn by passing the oil vapors therethrough, which process ls characterized by the fact that the temperature oi the contact mass during each of said steps of the entire cycle is within a range between approximately 600 F. and 1000 F., and said material is at all times maintained in its extended surface condition, and an inhibitor is at all times maintained in and distributed throughout said material sufficient to avoid catalytic decomposition of the oil and blanketing of the catalyst with carbon formed thereby.

6. A process of desulfurizing sulfur-bearing hydrocarbon oils which comprises vaporizing such oil and superheaiing its vapors, passing said vapors through a porous mass of contactmaterial having an extended surface of nickel poisoned with sulfur in substantially every part of the mass, continuing such passage until at least a part of the contact mass is substantially converted to sulfide by sulfur taken up from the oil, segregating from the oil at least a part cf the contact mass which has been thus converted to sulnde. passing through the contact mass an oxygen containing gas adapted to convert said sulfide to oxide, passing through said mass a reducing gas adapted to reduce said oxide to the metal, and again utilizing the reduced mass for desulfurization by the oil vapors therethrough, which process is characterized' by the fact that the temperature of the contact mass during each of said steps of the entireV cycle is within a range between approximately 700 F.'

and 900 F. and said material is at all times maintained in its extended surface condition and sulfur poisoning is at all times maintained in sub# stantially every part of the mass suiilcient to avoid catalytic decomposition of the cil and blanketing of the catalyst with carbon formed thereby.

7. The process as defined in claim 5, in which the passage of the oil through the contact mass is continued until at least the part of the contact mass which is to be segregated is so far converted to sulfide that it can be oxidized spontaneously by air at room temperature and without otherwise raising its own temperature. air is supplied to said mass for oxidation of the sulfide, and the temperature of the contact mass during said oxidation is kept within said range and overheating isprevented by a regulated supply of ste'am thereto during said oxidation.

8. The process as defined in claim 5, in which the passage of the oil through the contact mass is continued until atleast the part of said contact mass which is to be segregated is so far converted to sulfide that it can be oxidized spontaneously by air supplied at room temperature, and, without otherwise raising its own temperature, air is supplied to said mass at a temperature lower than that at which spontaneous combustion of the sulfide. and the temperature of the mass during the' oxidation is kept sulciently low that the reaction stops spontaneously by decrease of the sulde concentration before the sulfur poisoning of the catalytic activity of the mass is eliminated.

9. The process of treating petroleum oils for production of improved motor fuels which comprises passing the oil at temperature above F., at which catalytic decomposition of hydrocarbons into elements could occur, and in the presence of hydrogen, over and in intimate contact with a free metal selected from the class consisting of nickel, cobalt and iron in extendedsurface condition, said metal at all times during said treatment having a catalytic-inhibiting substance distributed over substantially its entire surface in amount sufficient to substantially avoid the decomposition of hydrocarbons into elements, which would otherwise occur and at least some of said free metal remaining exposed to the oil at all times during said treatment.

l0. The process of producing doctor-sweet products of reduced sulfur content from sulfur containing hydrocarbon oil which comprises passing such oil in vapor phase with addition of hydrogen at temperature above 700 F. at which catalytic decomposition of hydrocarbons into elements could occur and through a contact mass comprising a porous carrier having free metal selected from the class consisting of nickel, cobalt and iron extended on its surface in physical condition adapted to give it high surface activity but at all times during said treatment having sulfur distributed substantially throughout said surface as an inhibitor for the catalytic activity thereof and at least some of said free metal remaining exposed to the oil at all times during said treatment.

ANTONI SZAYNA.

' OERTIFIOATE oF CORRECTION.

Patent no. -275,299. February 17, 191m.

" ANTONI snm.

It is hereby certified that error appears inv the printed specification ofthe above numbered patent 'requiring correctionas follows: Page 6, first colmn, lines 5l te 5h, in the heading to the table, for "Acid treated 2O 1bs.'ac1d/bb1." read --Acid' treated 25 lbs. sc1d/'bb1.; page 9, first column, une 28, clam h, for base read based; and that the said Letters Patent should be read with this correction therein that the same mayl conform to the record of the case in the Patent Gffice.

Signed and sealed t'his 21st day of April, A. D. 1914?..

Henry Van Arsdale, (Seal) 4 Acting Commissioner of Patents.

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