US2145657A - Process for the hydrogenation of hydrocarbon oils - Google Patents

Description

Patented Jan. 31, 1939 PATENT OFFiCE rnocnss FOR. THE HYDROGENATION or HYDROCARBON OILS Vladimir llpatieff and Vasili Komarewslry, Chicago, lllL, assignors to Universal Oil Products iUompany, Chicago, lllL, a corporation of Delaware No Drawing. Application December 30, 1936, Serial No. 118,271

Ciai.

This invention relates particularly to the treatment of mixtures of hydrocarbons representing fractions produced in the refining of petroleum oils.

5 More specifically it is directed to a special process for efiiciently desulfurizing distillates of approximate gasoline boiling range which are too high in sulfur to permit their marketing in view of the present rigid specifications in regard to the sulfur content in motor fuels, which is seldom allowed to run over 0.10%.

The sulfur problem in petroleum refining attained major importancewith the extension of the producing fields from Appalachian to the Mid-Continent and Coastal regions, and an enormous amount of experimental work has been conducted to determine the types of sulfur compounds present in straight-run and cracked fractions from sulfur bearing petroleums and to develop practical methods for the elimination of the combined sulfur. It has been shown that sulfur occurs in practically every possible form of combination in varying proportions since free sulfur, hydrogen sulfide, mercaptans, thioethers, mm-

phenes, and thiophanes have all been identified. A limited success has attended the removal of these compounds or their combined sulfur, processes having been developed to substantially remove free sulfur and hydrogen sulfide and to to convert mercaptans to dialkyl disulfides having an inoffensive odor. The removal of the sulfur of thioethers or of the cyclic sulfur compounds has been the principal stumbling block and thus far, apart from the use of unusually vigorous and destructive chemical reagents which generally consume more hydrocarbon material than the removed sulfur, the only feasible methods for removing sulfur compounds have been the use of sulfuric acid of graded strengths and hydrogenation which produces hydrogen sulfide from the sulfur in the various types of sulfur compounds. The hydrogenation processes generally endeavor to employ catalysts to reduce the temperature, pressure, and excess of hydrogen necessary for accomplishing sulfur reduction but experience has shown that almost invariably the most active hydrogenating and desulfurizing catalysts are quickly rendered inactive by the formation of sulfides and the deposition of carbonaceous mate so rials to mask catalyst surfaces. The present process is an improvement in the art of desulfurizing by hydrogenating in the presence of catalysts.

In one specific embodiment the invention com- 55 prises the hydrogenation of petroleum oils and particularly those of gasoline boiling range for the desulfurization thereof using catalysts comprising metal sulfides mixed with alkali metal aluminates.

The effectiveness of the present type of mixed 5 catalysts in regard to both activity and life in desulfurization reactions. is due to the fact that their chief component is a sulfide itself incapable of being extensively altered by the products of sulfur compound decomposition under elevated 10 temperatures and pressures-of hydrogen and the fact that the sulfides are further improved by the incorporation therewith of alkali metal aluminates which serve as binders to increase the structural strength of the sulfides, as independent ill catalytic promoters and to some extent as chemical reactants for the removal of hydrogen sulfide from the sphere of the reaction as it is produced.

It is commonly recognized that the whole catalytic art is on a definitely empirical basis since 20 few rules have been evolved which will enable the accurate prediction of what particular materials may be effective in catalyzing a given reaction or combination of reactions. The foregoing statements, therefore, are not given with 25 the idea. of completely explaining the improved results obtained when utilizing catalysts of the present character and reliance is placed rather upon the fact that such improved results have.

been regularly observed when the mixtures were so employed.

A number of metal sulfides may be utilized as compounds of the preferred composite catalysts such as the sulfides of aluminum, iron, copper, nickel, cobalt, molybdenum, tungsten, antimony. 35 It will be observed that the above group of sulfides comprises those of the metals of the iron group, the elements in the lefthand column of group 6 of the periodic table and also sulfides of copper, aluminum, and antimony. These 40 have all been tried and found to be effective in varying degrees depending upon the type of sulfur compounds involved in different desulfurizing reactions. However, it will be seen that apart from the elements in the 6th and 8th groups men- 45 -tioned, the others represent no natural groups but are rather the result of experience. These sulfides represent substances which will be used alternatively with varying degrees of effectiveness but it is readily understandable that they are not exact equivalents. They may be made by any convenient method such as precipitation from solution by hydrogen sulfide under acid or alkallne conditions as the case may require or by the use of sodium sulfide. or polysulfide as a precipitant. As will be later described, the best method of manufacture of the preferred composite materials consists in incorporating the precipitated and dried sulfides with varying quantities of alkali metal aluminates and then forming by pelleting or extrusion methods. 1

Aluminates may be generally considered to be salts of metaluminic acid (HAlOa), salts of this acid with the following bases having been identified as distinct compounds: Sodium, potassium, lithium, ammonium, barium, calcium, strontium, beryllium, magnesium, zinc, thallium, manganese, iron, cobalt. Asa general rule the aluminates of the alkali metals are water soluble and the catalytic contact masses characteristic of the invention may be produced by adding single oxides or mixtures of oxides to such solutions as will be described in succeeding paragraphs. The aluminates of the other bases named are generally relatively infusible solids and made by dry methods consisting generally in heating the proper oxides with aluminum oxide in suitable proportions.

In the present invention the use of alkali metal .aluminates is preferred which group includes those of sodium and potassium and the other elements of this group: lithium, rubidium, and caesium. Obviously for practical reasons the use of sodium aluminate is preferred since this material is readily obtainable at a moderate price.

Sodium aluminate has been given various formulas such as, for example, AlNazOz and NaAlOz. Its formation depends upon the properties-possessed by alumina of acting as an acid in the presence of a powerful base. It may be prepared from bauxite and common salt by passing a current of steam through a mixture of these substances, by heating a mixture of bauxite,

sodium sulfate and carbon with later purification and by either heating cryolite with limestone or treating a suspensionof cryolite with milk of lime. The compound itself is a white difiicultly fusible amorphous solid which is readily soluble in water and in the present instance its usefulness depends primarily upon its action as a binder in holding the finely divided particles of sulfides together in forms of a given size and shape. Other possible actions have already been suggested. The technique of conducting hydrogenation for desulfurization by using the present types of catalysts is in general the same as that commonly employed in the industry utilizing other types of catalysts. Such conditions as temperature, pressure, and excess of hydrogen over that necessary for the formationof hydrogen sulfide will be determined by the percentage and refractoriness of the sulfur compounds which may be present. Thus when treating heterocyclic sulfur compounds of the nature of thiophene higher temperatures, pressures and excess of hydrogen will be employed than when desulfurizing fractions of petroleum which contain rather mercaptans and thioethers. Owing to the fact that the process is specially effective in removing thiophene sulfur, its greatest applicability lies in this field and later examples will show the types of results to be expected.

Catalyst may be employed as filler in tubes through which the vapors of oils to be dehydrogenated mixed with the requisite amount of hydrogen are passed or they may be employed in larger chambers through which oils are passed in liquid phase in continuous operation. An obvious method of procedure in batch operations is to 7 suspend the catalyst particles in liquid to be hydrogenated and introduce hydrogen above the The catalyst was prepared by mechanically incorporating equal parts by weight of antimony sulfide and potassium aluminate followed by compressing into small pellets of uniform size.

These were added to a mixture of xylene and' thiophene showing a total sulfur content of 4% by .Weight. 80 atmospheres of hydrogen was added to the pressure vessel containing the oil mixture and catalyst and the vessel was then heated gradually to a maximum temperature of 400 C. and held at this temperature until the pressure dropped and remained constant at a given point. Analyses of the oil mixture after washing with caustic soda to remove dissolved hydrogen sulfide indicated that approximately 80% of the sulfur originally present had been removed. A further recycling of this oil mixture effected a further 80% reduction so that the total sulfur content was then approximately 0.25%.

Example II In this case the catalyst consisted of approximately equal parts by weight of precipitated iron sulfide and potassium aluminate and using the same thiophene-containing mixture as in Example I and the same method of operation, an 89% sulfur reduction was effected at a single pass.

Example III The catalyst used in this case consisted of equal parts of aluminum sulfide and sodium aluminate and gave a 97% sulfur reduction in a single bomb treatment following approximately the same procedure as in Example I.

The character of the present invention is an improvement in the hydrogenation art and the unusually good results obtainable in its application will be seen from the foregoing specification and limited examples although neither section is intended to be unduly limiting upon its generally broad scope.

We claim as our invention:

1. A process for the hydrogenation of hydrocarbon oils which comprises subjecting said oils to contact with hydrogen in the presence of composite catalysts comprising an alkali metal aluminate and a metal sulfide corresponding to hydrogen sulfide whose hydrogen atoms have been replaced by a metal.

2. A process for the hydrogenation of hydrocarbon oils which comprises subjecting said oils to contact with hydrogen at elevated temperatures of the order of 150-400 C., and superatmospheric pressures of the order of approximately 10-100 atmospheres in the presence of composite catalysts comprising an alkali metal aluminate and a metal sulfide corresponding to hydrogen sulfide whose hydrogen atoms have been replaced by a metal.

3. A process for the hydrogenation of hydrocarbon oils which comprises subjecting said oils to contact with hydrogen in the presence of com- Mamet 5ft posite catalysts comprising essentially aluminum sulfide and sodium aluminate.

4. A process for the hydrogenation of hydrocarbon oils which comprises subjecting said oils to contact with hydrogen in the presence of composite catalysts comprising essentially iron sulfide and alkali metal aluminate.

5. A process for the hydrogenation of hydrocarbon oils which comprises subjecting said oils to contact with hydrogen in the presence of composite catalysts comprising essentially antimony sulfide and alkali metal aluminate.

VLADIMIR IPATIEFF. VASILI KOMAREWSKY.