Патент USA US2105464код для вставки
Patented Jan.‘ T8, 193 ,iati 2,105,464 ‘~ :I E ACTURE 0F MOTOR FUEL Waldo 0. am an Carroll A. Hochwalt, Dayton, @hio, assignors to Monsanto Chemical Com > pally, St. Louis, M0,, a corporation of Dela ware No Drawing. Application .iune 29, 1938, Serial No. 87,910 6 Claims. (Cl. ISIS-23) The present invention relates to a process of treating gasoline, motor fuels, and similar dis tillates to improve their properties, especially in regard to gum formation, sulphur content,,and similar characteristics. - The principal object of the invention is to pro vide a more efficient and economical method of producing gasoline and similar motor fuel dis tillates. Heretofore, it has been proposed to remove 10 gum from gasoline by treatment with various reagents. Not infrequently a reagent such as phosphoric acid, zinc chloride solution and the like, will remove the gum from a particular petro leum product but will not remove enough of the sulfur impurities to pass the speci?cations for motor fuels without ancillary chemical treat ment. , The- present invention affords an inexpensive and convenient means for accomplishing substan tially complete degumming of a gasoline product and sufficient desulfurization to pass the sulfur speci?cation even in the case of the very sour grades of petroleum products. According to the present invention a gasoline I is treated with a metal'oxide, such as an alkaline ferric oxide, and then subjected to a treatment economical manner without producing any sub stantial reduction in the other desirable proper ties of the original fuel. The process of the in vention usually produces an enchancement of the antiknock value of the fuel instead of the 5 diminution thereof obtained by other re?ning methods. . According to one method of practicing the in vention, the unre?ned fuel is passed in vapor form over Alpha-Lux (which is commercially 10 available precipitated ferric hydroxide that is strongly alkaline and used extensively in the in dustrial and domestic gas industry) at a tem perature of 375° to 425° C., at such rate or time of contact, that substantially no cracking results.‘ A suitable rate for a furnace consisting of a heat 5 ed tube of 1%,," internal diameter and 5 feet long ?lled with the ferric oxide in granular formis 1A2 gallon of liquid fuel per hour. The vapors are then scrubbed with phosphoric acid maintained at a temperature of about 190° to 200° C., ‘and are subsequently condensed. The optimum tempera ture for the oxide treatment will vary according to the time of contact, the activity and age of the catalyst, the amount and form of the sul fur impurities in the product and the extent N)5 of sulfur removal required. A suitable method . with phosphoric acid whereby a marked reduction which we have used to establish the temperature _ in sulfur content, as well as in gum-forming con ' of operation. is to test the ?nal petroleum prod 30 stituents, is effected, while at the same time the ole?nic nature of the fuel is not substantially af“ fected. The fuel thus treated is remarkably sta ble with respect to gum and color. Heretofore the methods of removing gum~ 35 forming constituents from gasoline and similar» distillates, for example, the we1l~known re?ning treatment with sulfuric acid, resulted in a lower ing of the ole?n content of the distillate, as well as a reduction in the gum value. A'lowering of 40 the ole?n content is undesirable due to the. loss of fuel thus produced, and the reduction in anti knock value of the re?ned distillate. On the other hand, the methods of reducing the sulfur content of fuels now in use, such as the doctor 45 treatment and alkaline hypochlorite solutions, are expensive and furthermore, yield fuels un I stable with respect to gum and color. The proc ess of this invention obviates such treatments and makes it possible'to effect marked vreductions in gum ‘value and sulfur content in a simple and uct to determine the effectiveness‘ of this ?rst step. As the activity of the oxide diminishes the temperature is increased. When effective re moval of sulfur is not longer economically pos sible, the oxide is regenerated in the known man ner, preferably with steam, or steam and air. To remove dissolved hydrogen sul?de and the like, the condensate may be washed with a mild aque 5 ous alkali or caustic alkali. By such a treatment a, gasoline has been im proved as shown in the following table. In 40 column I are shown the properties of the original fuel; column II shows the change produced when the vapors are not subjected to the subsequent phosphoric acid treatment, that is, when the va pors are passed only through the ferric oxide; column III represents the improvement obtained by the process as described; column IV shows the improvement obtained by treatment with phos phoric acid alone. The properties weredeter mined by the customary methods and were de 50 2 aroaaea termined by exactly the same procedure for each sample. III Origi nal Ferric Improved Phosphoric oxide acid treat-v process ment treated value (copper dish 10 Gum method, milligrams)_-__. 456 422 stability, minutes) _____ -_ 30 70 Gum test (oxygen bomb IV 2 6 220 Total sulfur content (lamp 0. 2O 0. l2 0. 11 0 ____________________ __ 0.46 Absent 0.015 bromate, centigrams)____ 54 52 ' method, %) ____________ __ Mercaptan sulfur content 15 Unsaturation (bromide 49 50 has a higher boiling point than the original gaso line passed through the acid and on distillation it yields a clear light colored liquid with a blue fluorescence which is believed to consist of poly-' mers of some of the original gasoline constituents. It is desirable to control the temperature of the phosphoric acid chambers so that little ornone of these polymers are volatilized with the vapors. ‘To prevent any spray of phosphoric acid or poly mer during the treatment, the apparatus is pro 10 vided with suitable ba?les or towers packed with any non-reactive filling material such as glass, coal, coke, etc. These provisions are more fully described in the applications of Carroll A. I-Ioch-v Walt and Waldo C. Ault, to which reference has already been made. - The improved process of using ferric oxide with I 20 11 Positive Poor C _ Octane rating IV Negative Negative . Excellent Poor Positive Excellent ‘ (antiknock)__'__ 60 60 G3 63 a phosphoric acid treatment produces a result heretofore unexpected of a combination of the two processes. The treatment with the ferric oxide, in some manner which is not clearly under stood at present, besides removing a definite pro portion of the sulfur bodies present in the original Similar advantageous results have been ob- ' distillate, leaves the unremoved residual sulfur 25 tained with a Wide variety of gasolines of differing properties. The method is particularly valuable for ‘fuels with high sulfur contents and high gum values. 30 ' , The treatment with phosphoric acid may be carried out in the vapor phase as described here inabove or as further described in the application of Carroll A. Hochwalt and Waldo C. Ault, Serial Number 66,896, filed on March 3, 1936. Alter ' native procedures consist in effecting the ‘treat ment with'the aid of steam, or conducting the treatment in the liquid phase, as described in the applications of Carroll A. Hochwalt and Waldo C. Ault, Serial Numbers 66,893 and 66,895, ?led on March 3, 1936. The‘ phosphoric acid may be 40 dispersed on pumice, clay or similar solid material to increase its surface of contact with the mate rial undergoing treatment. For some purposes a treatment with the phosphates of copper, nickel, cadmium, zinc, cobalt, chromium, iron and other 45 metals, according to the method described in the application of Carroll A. Hochwalt and Waldo C. ‘Ault, Serial Number- 66,894, ?led March 3, 1936, is preferred. When such solid agents are used the treatment can be conducted in two separate 50 ‘units, such as a tube containing ferric oxide and another tube containing the metallic phosphate. 55 or the two catalysts may be placed in the same tube, or the two solid treating agents may be in termingled and used in va single unit. A concentration of phosphoric acid especially appropriate for the practice of the invention is one which corresponds to tetrapyrophosphoric acid (H6P4013), which has a phosphorus pentox 60 ide (P205) content of approximately 84%. This acid can be made by adding to phosphoric acid, bodies in what might be called an activated con 25 dition, that is, in such a condition that they are more completely removed in the subsequent phos phoric acid treatment. It has been found that less advantageous results are obtained if the phosphoric acid treatment precedes the desulfur 30 ization treatment and that when two gasolines, (1) an unre?ned gasoline, and (2) a gasoline pre treated with ferric oxide, both with an equivalesnt total sulfur content and corresponding in other properties, are treated with phosphoric acid in 35 exactly the same way as described herein, that gasoline previously treated with ferric oxide will ‘ have a lower residual sulfur content than the gasoline not previously treated. The action of the ferric oxide appears to affect favorably the susceptibility of the sulfurto removal by treat 'ment with phosphoric acid or similar gum remov ing reagent. While the treatment with phos phoric acid to remove the gum is preferred and possesses distinct advantages, other known means 45 for accomplishing this step by polymerization may be employed’. For example, acid reacting salts and aqueous solutions thereof have been proposed for this step, such as zinc chloride and the like. The function of the ferric oxide from ,the above 50 considerations is primarily that of rendering the sulfur compounds in the original gasoline more completely susceptible to removal. Other mate rials which are effective, especially when ren dered distinctly alkaline or basic, are: iron ores, 55 copper oxide, bauxite, aluminum oxide, lead ox ide and calcium oxide; in general, alkaline metal lic oxides or hydroxides may be used. Salts or metals which can give rise to metallic oxides during the treatment may be employed by placing 80 for ‘example, commercial syrupy acid having a " them in the tube or other suitable apparatus and phosphorus pentoxide content of about 55%, an treating them in such a manner that the oxide additional amount of phosphorus pentoxide until remains; thus, for example, the tuoe maybe filled with iron ?lings and air passed therethrough 65 an acid of the appropriate concentration is ob tained. Phosphoric acids ‘containing additions at a raised temperature until oxidation to ferric of phosphorus pentoxide such that their contents of phosphorus pentoxide range from about 50 per cent and upward, produce satisfactory results in 70 re?ning most gasolines, but the optimum concen tration of the acid and conditions for its usefor ' any particular purpose are easily determined by previous tests. In the phosphoric acid, a dark colored liquid will be seen to deposit during the 75 process of treating crude gasolines. This liquid oxide has‘been accomplished. During the treat ment some metal sul?des may be formed. Oxida- - tion with air at a raised temperature,-preferably with the addition of steam, is sufficient to recon vert these sul?des to oxides. The oxide, especi ally when strongly alkaline, activates the sulfur compounds in the original distillate to a form whereby they are more easily removed in the sub sequent step and need not of itself have any de 70 sulfurizing action. 75 3 I 2,105,464 Inasmuch as the conditions and reagents speci ?ed above comprise preferred embodiments of the invention, it is to be understood that the inven tion is not limited thereto, nor to any theory of the chemical actions herein involved, but is sub .iect only to the limitations de?ned in the ap pended claims. What we claim is: 1. In the treatment of a cracked distillate of 10 motor fuel boiling range, rich in sulfur and gum forming constituents, to form a distillate of motor fuel quality, the steps which include subjecting the distillate while in vapor phase to a metal - oxide which has been rendered distinctly alkaline, 15 ‘ whereby sulfur impurities are rendered removable forming constituents, to form a distillate of motor fuel quality, the steps which include subjecting the distillate while in vapor phase to a distinctly alkaline ferric oxide, whereby sulfur impurities are rendered removable by phosphoric acid treat ment and subsequently scrubbing the distillate with phosphoric acid under conditions whereby polymerizable and surfur containing impurities are removed without substantially reducing the octane number of the motor fuel. 10 4. In the treatment of a cracked distillate of motor fuel boiling range, rich in sulfur and gum forming constituents, to form a distillate of motor fuel quality, the steps which include subjecting the distillate while in vapor phase to a distinctly 15 by phosphoric acid treatment and subsequently scrubbing the distillate with phosphoric acid under conditions whereby polymerizable and sulfur containing impurities are removed with 20 out substantially reducing the octane number of the motor fuel. alkaline ferric oxide, whereby sulfur impurities are, rendered removable by phosphoric acid treat ment and subsequently scrubbing the distillate 2. In the treatment of a cracked distillate of motor fuel boiling range, rich in sulfur and gum forming constituents, to form a distillate of motor without substantially reducing the octane number 25 fuel quality, the steps which include subjecting the distillate while in vapor phase to an alkaline ferric oxide, whereby .sulfur impurities are ren dered removable by phosphoric acid treatment and subsequently scrubbing the distillate with 30 phosphoric acid under conditions whereby poly with a polymerizing agent under conditions whereby polymerizable gum forming and sulfur 20 containing impurities are rendered removable of the motor fuel. 5. The method as de?ned in claim 4 and further characterized in that the ferric oxide treatment 25 is effected at approximately 375-425° C. and the phosphoric acid treatment is effected at approxi mately 190-200° C. merizable and sulfur containing impurities are 6. The method as de?ned in claim 4 and char acterized in that the ferric oxide is substituted by an alkaline oxide of another metal which has removed without substantially reducing the oc been rendered distinctly alkaline. tane number of the motor fuel. _ 3. In the treatment of a cracked distillate of 35 motor fuel boiling range, rich in surfur and gum I WALDO o. AUL'II‘. CARROLL A. HOCI-IWALT.