US2270058A - Refining of mineral oils - Google Patents

Description

Jan. 13, 1942. M c, JONES 2,270,058

REFINING OF MINERAL OILS .Filed May 15, 1940 Patented Jan. 13, 1942 REFINING OF MINERAL OILS Minor 0. K. Jones, Elizabeth, N. 3., assignor to Standard Oil Development Company, a corporation of Delaware Application May 15, 1940, Serial No. 335,239

8 Claims.

The present inventionrelates to the refining of mineral oils. The invention is more particularly concerned with the removal of objectionable sulfur compounds from hydrocarbon oils, especially petroleum oils boiling in the motor fuel, kerosene and gas oil boiling ranges. In accordance with the present process,sulfur-containing oils of this character are contacted with a solid material selected from the class of alkali metal aluminum silicates of the zeolite type at elevated temperatures and pressures.

It is known in the art to treat mineral oils, particularly petroleum oil distillates, and the like with various contacting masses such as clay, aluminum oxides and other metallic oxides under various temperature conditions in order to remove objectionable sulfur and related sulfur-containing compounds. For example, a conventional procedure for the removal of sulfur compounds from petroleum oils boiling in the motor fuel boiling range is to pass the oil in the vapor or liquid phase over bauxite under relatively wide varying temperature conditions. The desuliurized oil, after removal from the desulfurization catalyst; is usually treated in a manner to improve its color and color stability. This latter operation is generally accomplished by clay contacting the oil in any desirable manner. It is also known to use various other solid substances .for the removal oi sulfur compounds from feed oils which, due to their nature, have not been particularly effective for the production of high quality desulfurlzed products.

I have now discovered a process by which it is possible to substantially completely remove undesirable sulfur compounds from mineral oils containing the same which comprises contacting the sulfur containing petroleum oil with a solid material selected from the class of alkali metal aluminum silicates of the zeolite type at elevated temperatures and pressures. My process not only efliciently and economically removes the undesirable sulfur compounds, but also produces a high quality desulfurized product having improved color, color stability, a relatively low gum content, an improved octane number as wellas an improved susceptibility for knock suppressing agents such as tetraethyl lead. I have discovered that if the desulfurization operation be conducted at elevated. pressures and temperatures employing these reactants, the effectiveness of the same will be materially unexpectedly increased. The desulfurized product will require a less severe clay treatment and in many instances may entirely by-pass clay treating, thus efi'ecting increased yields and materially reducing manufacturing costs. In accordance with my process, sulfur-containing petroleum oils are desuifurized utilizing zeolites at pressures above about '75 pounds per square inch, preferably pressures above about 350 pounds per square inch. The temperatures employed are in the range at which substantially no cracking or decomposition of the oil will occur.

The process of my invention may be readily understood by reference to the attached drawin illustrating modifications of the same. Feed oil whichior the purposes of description is taken to be a crude petroleum oil, is introduced into distillation unit I by means of feed line 2. Temperature and pressure conditions are regulated in distillation unit I which may comprise any number of units arranged in any desirable manner to produce a prime cut fraction boiling in the boiling range below about 400 F., a gas oil fraction and a reduced crude fraction. The

, prime cut fraction is removed overhead by means lation unit I in which a separation is made hetween the relatively lower boiling constituents or light prime cut'and the relatively higher boiling constituents or heavy prime cut. The light prime cut is removed overhead by means of line 8, passed to sweetening unit 9, removed by means of line Ill, and uiually passed to finished motor fuel blending. The gas oil fraction is removed from distillation unit I by means of line H, while the reduced crude fraction is removed by means of line I2. These fractions are passed to cracking coils l3 and I4, respectively. The cracked products boiling in the motor fuel boiling range are removed by means of lines I5 and I6, while the gases, tar and heating oil fractions are re- 'moved by means of lines l1, l8, I9, 20, 2|, and

22, respectively. The cracked naphtha is introduced by means of line 30 into zeolite treatin plant 3| which may comprise any number of zeolite treating units arranged in any suitable manner. Similarly, the heavy primelcut removed from distillation unit I is introduced by means of line 32 into zeolite treating plant 33. For purposes of description it is assumed that the zeolite contacting units 3| and 33 are packed with a naturally occurring hydrated sodium aluminum silicate which may be represented by the formula NaHeAlSiOv. Zeolite desulfurization zones 3| and 33 are provided with suitable distributing and contacting means, as well as means adapted for the regeneration or revivification of the zeolite. These desulfurization zones are also provided with means adapted to maintain within said zones the desired temperature and pressure conditions. The zeolite desulfurized oils are removed from the zeolite zones by means of lines 34 and 35, respectively. In general, the desulfurized oil is introduced into clay contacting plant 23 by means of line 24. The clay contacted oil is removed by means of line 25 and introduced into distillation or rerunnirig unit 26. The zeolite clay contacted oil of the desired end point is removed overhead from distillation unit 28 by means 01' line 21 and introduced into sweetening unit 9 and passed to motor fuel blending by means of line iii. A heavy residue may be withdrawn from distillation plant 28 by means of line 28 and disposed of as desired. The zeolite desulfurized oil in many instances may be withdrawn from the zeolite contacting units and by-pass clay contacting unit 23 by means of line 29 and handled as a finished product with respect to sulfur concentration, gum content, color and color stability. Clay contacting zone 23 may comprise any number of units arranged in any desirable manner. These units are provided with suitable contacting means as well as means for maintaining a desirable temperature and pressure.

The process of the present invention may be widely varied. Although the process is adapted to the removal of sulfur compounds from any oil by means of zeolites, it is Particularly adapted to the removal of mercaptan compounds from the relatively lower boiling petroleum oils boiling in the gas-oil, particularly in the motor fuel boiling range.

The solid desulfurizing material employed is a reactant selected from the class of alkali metal aluminum silicates of the zeolite type. The preferred reactants are the naturally occurring alkali metal zeolites. naturally occurring alkali metal zeolites be of the hydrated variety. A particularly desirable substance comprises a naturally occurring hydrated sodium aluminum silicate, a species of which may be represented by the following formula: NaI-IsAlSiOm Although these desulfurizing reactants may be employed in the naturally occurring state, they are preferably surface conditioned by subjecting the same to a preheat treatment. In general, this preheat treatment is conducted under conditions which will not effect the chemical combination of the substances or which will not produce any substantial hydration of the same. Usually atmospheric pressure is employed and the temperatures are in the range from about 500 F to 1200 F., preferably in the range from about 800 F. to 900 F.

The desulfurizing operation is conducted at a temperature, pressure and time of contact so regulated that substantially no decomposition or cracking of the feed oil occurs. It is essential that the pressure employed be above about 75 pounds per square inch. The temperature should be in the range above about 600 F., preferably in the range above about 800 F., generally in the range from about 810 F. to 840 F.

The feed rates per volume of desulfurizing reactant employed will be a function of the particular reactant utilized, the character of the feed oil, the type and concentration of the sulfur compounds present, and upon general operation conditions. When employing a naturally occurring hydrated sodium zeolite, the surface of which has been prepared by a suitable pre-heat treatment for the removal of sulfur compounds from petroleum oils boiling in the motor fuel boiling range, the feed rates are preferably from about 0.5 to 2.0 volumes of feed per volume of catalyst per hour.

In order to further illustrate the invention, the

It is also desirable that these following examples are given which should not be construed as limiting the same in any manner whatsoever.

Example 1 A cracked petroleum oil boiling in the motor fuel boiling range and produced from a gas oil derived from a Quire Quire crude oil was contacted with a naturally occurring hydrated sodium aluminum zeolite having the formula NaHeAlSlOv, and clay contacted under the following conditions:

Temperature-zeolite stage F.-- 800 Pressure, lbs/sq. in. gauge, zeolite stage-- 100 Feed rate, vol. of oil/vol. of zeolite hour---" 1 Temperature, clay stage F 500 The treated oil was rerun to a 385 F. E. P. The inspections on the contacted oil. along with the inspections on an identical 011 not zeolite and clay contacted, but rerun to a 385 F. E. P., are as follows:

' Crackedfeed oil rerun to and I to ted d F ror im to Color, Saybolt -0 +30 Mg. inh./l00 ml 6 5 Inhibitoremployed(tradename). DuPontIlfl Du Pont I16 Breakdown min. (uninhibitod) 60 36 Breakdown Min. (inhibited) so ass Copperdishgum/l00ml(uninhibited)" 44 15 Copper dish gum (inhibited) 32 3 Acid heat, A. S. T. M., F- 141 74 Sulfur 0. 177 0. 104 Octane number A. B. T. M cle 77. 7 78. 3 +a.o ml. '1. E. L 82.7 34. 2 Engler distillation:

Percent distilled 158 F l3 14 Percent distilled 350 F 90 00 F. B. P.F 384 390 Percent recovered n 98.0 97. 6

Test for measuring the stability of an oil. 25 cc. of oil are placed in a bomb at a temperature of 212 F. under oxygen pressure 01100 lbs./sq. in. The time in minutes is measured during which the pressure drops 2 lbs.

"Copper dish gum, cc. of oil are placed in a copper dish and the oil evaporated at 212 F. The gum on the dish is measured.

From the above, it is apparent that material substantial benefits are secured by processing the oil in a manner according to the present invention.

A portion of the identical feed oil was processed in a similar manner employing bauxite and clay. The inspections on this oil compared with the inspections on the oil secured by contacting with zeolite and clay are as follows:

Cracked feed Cracked feed oil, bauxite oil, zeolite and clay and clay contacted contacted and rerun and ram to 385 F. to 385' 1*.

Color, Saybolt +30 +3t Inhibitor employed (trade name) Du Pont #16 Du Pont I18 Mg. inh./l00 ml 6 5 Breakdown, min. E 40 86 Breakdown, min. ted 365 386 Copper dish gum mg./100 ml. (uninc ist 7166""F'GH' m opper gum mg. m hiblted) 4 3 Acid heat, A. S. T. M., "F 88 74 Octane number, A. S. T. M., clean..- 78. 9 78.3 +3 cos. of lead 8t. 3 84. 2 Engler distillation:

I. B. P 01 01 Percent distilled 158 F l4 14 F. B. P. F 388 800 From the above, it is apparent that the zeolite produces a finished product superior to the prodnot produced by bauxite, particularly with respect to the breakdown of the inhibited material and as measured by the respective acid heats.

Example 2 A West Texas light prime cut naphtha was contacted with the zeolite employed in Example 1 under the operating conditions employed as described in Example 1. The inspections on the contacted product compared with the inspections on the feed oil are as follows:

West- Texas West Texas light P. 0. light P. C. zeolite and iced oil clay conrerun tacted and rerun Color. Saybolt 30 30 Copfer dish gum l1 3 Aci heat, A. S. 'l. M., 2.0 4 Sulfur-weight, percent 0. 138 0. 024 Octane number, A. S. T. M., clear 61. 2 85.0 +3 cc.T.E.L 74.6 81.6 Engler distillation:

I. B. P 94.0 109 Percent distillate 158 F l5. l3. 5 Percent distillate 302 F 88. 0 91. 5

above about '75 pounds per square inch and at a temperature above about 600 F., said temperature and pressure being in the range at which substantially no cracking or decomposition of the oil occurs.

2. Process in accordance with claim 1, in which said mineral oil is a petroleum oil boiling in the motor fuel boiling range and in which said oil is contacted in the liquid phase.

3. Process in accordance with claim 1, in which said mineral oil is a petroleum oil boiling in the motor fuel boiling range and in which said oil is treated with a hydrated sodium aluminum silicate at a temperature in excess of about 800 F.

4. Process for the removal oi objectionable sulfur compounds from petroleum oils boiling in the motor fuel boiling range which comprises treating said oil in an initial stage with an alkali metal aluminum silicate of the zeolite type at elevated temperatures and pressures under conditions at which substantially no cracking or decomposition of the oil occurs, said pressure being above about pounds per square inch and said temperature being in the range above about 600 F., and then further contacting said oil in a secondary stage with clay.

5. Process in accordance with claim 4, in which said oil is contacted with a naturally occurring hydrated sodium aluminum silicate of the zeolite type in the liquid state.

6. Process in accordance with claim 4 in which said oil is contacted with a naturally occurring hydrated sodium aluminum silicate of the zeolite type at a, pressure of about lbs/sq. in. gauge and at a temperature in excess of about 800 F.

7,. Process for the removal of objectionable sulfur compounds from petroleum oils boiling in the motor fuel boiling range, which comprises treating said oil in the liquid state in an initial stage with a naturally occurring alkali metal aluminum silicate of the zeolite type at elevated temperatures and pressures at which substantially no cracking or decomposition of the oil occurs, said pressure being in the range above about 75 pounds per square inch and said temperature being in the range above about 600 F. 8. Process as defined by claim '7, in which said pressure is in the range above about 350'pounds per square inch and said temperature is in the range from about 810 F. to 840 F. i MINOR C. K. JONES.

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