US2477386A - Method of improving the adsorbent and decolorizing properties of georgia-florida fuller's earth - Google Patents

Description

Patented July 26, 1 949 METHOD OF IMPROVING THE ADSORBENT AND DECOLORIZING PROPERTIES OF GEORGIA-FLORIDA FULLERS EARTH William S. W. McCarter, Ardmore, Pa., assignor to Attapulgus Clay Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Application August 21, 1948, Serial No. 45,572

10 Claims. 1

The present invention relates to a process for improving the decolorizing efiiciency of Georgia- Florida type fullers earth, and relates more particularly to increase the effective life of such earth upon repeated use and regeneration in the field of oil decolorization and refining.

It has been known heretofore that the decolorizing efl'iciency of Georgia-Florida type fullers earth may be substantially increased upon both a Weight and. volume basis by mixing with raw fullers earth a small amount of a water-soluble alkaline reagent and suflicient water to render the earth plastic, extruding the mixture at an elevated pressure, drying the extruded earth, reducing the dried earth to granular particles, and calcining the granular particles at 800 F. to 1200 F. Such process is disclosed and claimed in United States Patent 2,363,876 to W. A. La- Lande, Jr.

In utilizing fullers earth for the treatment of petroleum products, especially for the decolorization of lubricating oils, petrolatum, and waxes, it is the practice to percolate the petroleum fraction through thermally activated fullers earth until the desired degree of refining or decolorization is no longer obtained. It is not feasible, economically, to discard the used earth at this point. Instead, the earth must be treated to restore its adsorptive properties for reuse. This regenerative treatment usually involves washing the spent earth with a solvent such as naphtha, purging the washed spent earth with steam, drying the steamed earth, and calcining or burning the dried earth in the presence of air to oxidize and remove strongly adsorbed tars, asphalts, and other carbonaceous matter.

I have found that under this regenerative treatment, the fullers earth containing the added alkaline reagent produced according to the La-. Lande process aforementioned, rapidly deteriorates in decolorizing or' adsorptive efiiciency. I have also found, however, that this deterioration in efliciency can be decreased substantially, without any effect upon the beneficial action of the alkaline reagent, by neutralizing the alkaline reagent at any oneof several stages during the preparation of the improved earth following the initial mixing or impregnation of the earth with the alkaline reagent. The neutralization is effected using a mineral acid, preferably diluted with water if the initial acid was concentrated. Acids such as sulfuric, hydrochloric, nitric, .phosphoric, or hydrofluoric may be used, preference being had for sulfuric acid due to its availability, cheapness, and relative ease of handling. The amount of acid used is only that necessary to neutralize the alkaline reagent originally incorporated in the earth, since amounts greater than the stoichiometric equivalent are not beneficial and, in fact, may have an adverse effect upon the earth. As a matter of fact, it is well known that Georgia-Florida fullers earth is not improved by conventional acid activation as practiced with montmorillonite sub-bentonites, and fullers earth from the vicinity of Attapulgus, Georgia, is actually harmed by acid leaching (U. S. Dept. Interior, Geol. Survey #3 (1933) pages 45-49). It is, therefore, emphasized that the neutraliza tion of the fullers earth containing added alkaline reagent, in accordance with this invention, is not an acid activating treatment and is not to be confused therewith.

In carrying out this invention, the amount of alkaline reagent initially incorporated in the fullers earth must be held within the range of 0.1% to 1.75% by weight, based upon the dry or volatile-tree earth, otherwise the adsorbent or decolorizing eificiency is adversely affected, even though the alkalized earth is subsequently neutrailized with mineral acid. It is preferred to use from about 0.75% to 1.50% of alkaline reagent, about 1% of a reagent such as sodium hydroxide giving excellent results. Among the reagents reacting alkaline in aqueous solution which may be employed in accordance with this invention are the oxides, hydroxides, peroxides, carbonates, bicarbonates, secondary and tertiary phosphates, and silicates of Na, K, Li, and NH4 which are soluble in water to substantial extent. Due to their availability, effectiveness, and non-corrosive properties, the alkali metal hydroxides, and particularly sodium hydroxide, are preferred. Other alkaline reacting substances which may be employed are the alkoxide and phenolates of strong bases; soluble magnesium, calcium, and barium salts of weak acids; alkali metal aluminates, zincates, plumbites, arsenites, aresenates, antimonoites, stannites, stalnnates chromites, manganates, and phosphites; amides of metals forming soluble strong bases, quaternary bases such as tetralkyl ammonium hydroxides, tetraryl ammonium hydroxides, and mixed alkaryl ammonium hydroxides; hydrazine, hydroxylamine, and other soluble organic bases.

In accordance with the present invention, raw

fullers earth of the type obtained from the Georgia-Florida fullers earth deposits and containing natural moisture (40% to 50% by weight) is passed to a roll crusher wherein the lumpy earth isreduced to relatively fiat fragments. The earth from the crusher is introduced into a conventional pug mill in which the earth isintimately mixed with the alkaline reagent in aqueous solution, the quantity of agent being of the order or 0.1% to 1.75% by weight, .fba'sed upon volatilefree earth, and preferably "about 1% by .weight. Depending upon the initial moisture content of the raw earth, the concentration ,of the alkaline solution is adjusted to give ,atoital volatile-matter content (V. M.) in the earth of the order of 45% to 60% by weight, and preferably 52% to 56% by weight. The plastic, alkalized earth may then be subjected to any of the following procedures involving neutralizing and converting-the earth into an improved adsorbent and decolorizingaeent.

For example, the plastic earth containing 1% of sodium hydroxide and 54% volatile content (water) was mixed with sufficient dilute sulfuric acid concentration) onlyto neutralize .the added alkali, .the neutralized earth was washed with :Water to remove .the soluble salts .formed, and the washed earth was dried .to 5.4% -.volatile content. This earth .was then extruded through an auger extrusion .machinehavinga 2 inch diameter augerand a barrel 1.4 .inches in length ;-provided at the dischargeend-with a die ,pl-ate linch thick containing a plurality .of M; inch diameter apertures. Extrusion was accomplished at .a

fairly high pressure, 1. .e., above 100 pounds per sp uare :in-oh, the usual pressure range being of the order of 400 to .1200 ,pounds .per square .inch. The moist, extruded earth discharged from the die plate apertures wasdried at 250 F. to 300 F. to avolatilecontent ofabout 1.5% .by weight. The dried earth was then reduced to granular .particles by grinding, and the resulting particles .of desired size, for example, .30-60 mesh were .calcined at 900 F. for minutes, and the calcined product was screened to remove particles finer than .50 mesh. The .calcination step may .be performed at any temperature within the range .of 800 F. to 1200 ,F., and the particle size may be varied as desired.

The .decolor-izing eificiency of the improved i-uller s earth was determined by solution filtration of Pennsylvania cylinder oil stock 60% .by

volume naphtha-% by volume cylinder stock) through a given weight of earth at 135 F. to 6 N. P. A. color. The volume of filtrate of -6 N. P. A. color thus obtained, when compared with the volume of filtrate of .the same color obtained by liltration through commercial f-ullers earth, is indicative 0f the decolorizing efiiciency of the improyed earth. Commercial iullers earth isobtained by drying raw Georgia-Florida earth, grinding, screening to 30-60 mesh, calcining at 900 F., and removing particles finer than .60 mesh by rescreening. The weight efiicien-cy and volume efliciency upon the first use of commercial iullers earth is arbitrarily designated 100%. To determine efficiency upon repeated use and regeneration of the improved earth, the used im'- proved earth was drained of oil, washed with naphtha, steamed and air blown, and finally re- Number of Uses 1 2 3 4 5 6 v. M., per cent 3 .0; 2;0 1.}9 1. '9 1.9 2.0 Vol. Wt.,1bs./cu.ft 31.1 31.6 32.6 33.1 33.4 33.8 Wt. efficiency, per cent"... 131 136 141 141 136 Vol. eificiency, per cent... 127 133 134 144 142 137 In the "above example, neutralization of the "earth waseirectedimmediately after the thorough incorporation o'f'the alkaline reagent in the earth. :However, the samebeneficial results may be ob- .tained by neutralization after extrusion, as is iilustrateii below.

For example, 1% of sodium hydroxide and sufficient water to give 54% volatile matter content was added to raw fullers earth in a pug mill and the mixture was thoroughly milled. The resulting plastic, alkalized earth was then extruded as in ;the first example, and the extruded e'a rt-h "was then treated with :dilute .sulfuric acid in an amount chemically equivalent to tiresalkali Iinitially added. Following :the neutralization, the

earth was waterwashedfto remove soluble :salts,

Number of Uses i. l r 2 f 3 i 5 '-6 V.M.,per-c'ent 3.1 251 9 17- 15s as Wt. efiiciency per cent- 139 141 138 154 Volvefliciency,per eenth"; 134 145 149 1 H45 146 =l44 In Example 2, neutralization was efiect'ed a fter extrusion, and a second extrusion was required, since the initial -'extrud'ate disintegrated into fines during the neutralization. in another modification of this invention, 1% of sodium hydroxide andsufii'cient water to give 54% volatile -content was added to raw full-ers earth in 'a'pug mill "and the mixture was thoroughly milled. The resulting plastic, alkalized earth was then extruded'as in the first example, and the extruded 'earth was dried and thereafter treated with sufficient sulfuric acid'to neutralize the added alkali. During neutralization, the extrudate disintegrated into fines, and this material was water washed to remove soluble salts. The washed earth was redried to 154% volatile content, again extruded, dried, round, screened to 30-60 mesh, and calcined at 900 F., the material finer than '60 mesh being thereafter screened out. The decdroi'ization tests upon this improved earth are set forth below, and were carried out as in Example 1.

Vol. efiiciency, percent.

.In Example '3, neutralization carried out after the initial extrusion and drying. However, as shown in the following Example 4,, neutralizacined at 900 F. for 30 minutes, and the calcined earth, after cooling, and removal of particles finer than 60 mesh, was treated with sulfuric acid in an amount sufficient only to neutralize the alkali initially added. The neutralized earth was water washed to remove soluble salts and dried at elevated temperature. The tests upon this material are shown in the following table, and were carried out as in Example 1.

Number of Uses 1 2 3 4 5 6 v. M., Percent 2.9 2.2 2. 1.9 1.9 2.0 V0]. Wt. lbs/cu. It 34. 4 34. 4 35. 4 35. 35. 5 35. 6 Wt. efliciency, percent 135 136 131 125 121 120 Vol. efiiciency, percent- 143 144 145 138 134 133 In order to compare the efiiciency .of the lullers earth produced in accordance with this invention, with alkalized fullers earth of the prior art which has not been neutralized, the following example is presented. To raw fullers earth was added 1% of sodium hydroxide and sufiicient water to give a volatile content of 54-.%, and the mixture was thoroughly milled in a pug mill. The resulting plastic earth was then extruded as in Example 1 and the extrudedearth was dried, ground, and screened to 30-60 mesh, calcined at 900 F. for 30 minutes, and again screened toremove particles finer than 60 mesh. In this instance, no neutralization was carried out at any stage of the process. The calcined 30-60 mesh earth was then tested for decolorizing efficiency as inExample 1, and the results are given in the following table.

1 It will be noted from the above. that the un-.

neutralized earth, after the 4th use and regeneration, rapidly declined in both weight and volume efficiency, whereas the earths prepared in accordance with thisinvention retain a relativelyhigh decolorizing efliciency even after the 6th use and regeneration. Although not shown here. these earths still retain a high efficiency even through 10 to cycles of use, and the rate of decrease in efliciency is very slow in comparison with unneutralized, alkalized earths.

In carrying out the neutralization step, it is important that only sufiicient mineral acid be used to react with the alkaline reagent initially incorporated in the earth. In other words, chemically equivalent or stoichiometric amounts of acid are employed, there being no excess acid which might react with the earth and. cause degradation thereof. The concentration of the acid may vary over a considerable range, 1. e., 5% to 85 however, it is preferred to use relatively dilute acid, for example, sulfuric acid of 10% to 25% concentration.

To illustrate the effect of an excess amount of acid-in treating the alkalized earth, the following example isgiven. To raw fullers earth was added 1% of sodium hydroxide and sufiicient water to give 54% volatile content, and the plastic earth was milled and then extruded as described in Example I. The extruded earth was dried at 750 F. to prevent disintegration in the dilute acid: subsequently employed to neutralize the earth. The dried earth was ground and screened to 30-60 mesh, and then divided into two equal parts. One part was neutralizedwith a stoichiometric proportion of dilute sulfuric acid, while the second. part was treated with 3 times the stoichiometric proportion of acid. The treated earths were then water washed to remove soluble salts, dried, and calcined at 900 F. for 30 minutes, any material finer than 60 mesh then being separated by screening. The earth samples were then tested as described in Example 1, and the sample neutralized with astoichiometric amount of acid. had a volume weight or 32.6 pounds per cubic foot and a volume eificiency of 127%, whereas the sample treated with 3 times the stoichiometric amountof acid had a volume weight of 31.8 and a volume efliciency of 119.8%. apparent that the use of acid in excess of that requiredto effect neutralization is detrimental to the efiiciency of the earth. i

While, in general, it is customary to employ fullers earth of 30-60 mesh for the percolation decolorization of oils, it is of course within the scope of this invention to produce earths of any desired mesh, for example, 4-8, 10-60, 20-80, or even finely divided earth of 100, 200, 300 or finer mesh. In the processing of the earth, it is the usual practice to simply dry the final product, for example, at 250 F. to 400 F. to a volatile matter content of about 15 by weight, and market same at that volatile content. Prior to use in decolorizing oils or other materials, the user generally calcines the product at 800 F. to 1200 F. to a volatile content of 1.5% to 3% by weight. The improved earths of this invention may be employed in the decolorization or refining of hydrocarbon oils, waxes; animal and vegetable oils and fats, and the like. 1

I claim: I i I 1. In a process for improving the decolorizing efficiency of Georgia-Florida type fullersearth involving mixing the earth with from 0.1% to 1.75% by weight of a water-soluble alkaline rethe extruded earth,the step which consists intreating the earth with mineral acid in an amount sufficient only to neutralize the added alkaline reagent after said reagent has been thoroughly incorporated in the earth.

2. In a process for improving the decolorizing efi'iciency of Georgia-Florida type fullers earth involving mixing the earth with from 0.1% to 1.75% by weight of a water-soluble alkaline reagent and sufficient water to give a plastic earth containing from 45% to 60% of water, extruding the plastic earth at elevated pressure, and drying the extruded earth, the step which consists in treating the earth with sulfuric acid in an amount stoichiometrically equivalent to the alkaline reagent added, after said reagent has been thoroughly incorporated in the earth.

3. A process for improving the decolorizing emciency of Georgia-Florida type fullers earth, which comprises intimately mixing with the earth from 0.1% to 1.75% by weight of a water-soluble It is, therefore,

crevasse alkaline reagent and anc ent water to give a plastic earth containing from 45% to 60% of water, treating the earth with mineral acid in an amount sufiicient only to neutralize the added alkaline reagent, water washing the treated earth to remove soluble salts, adjusting the water conwater to give a plastic earth containing from 52% to 56% of water, treating the earth, with sulfuric acid in an amount sufficient only to neutralize the added sodium hydroxide, water. washing the treated earth to remove soluble salts. adjnsting the water content of the washed eartlg to a value between 52% to 56 %,extruding the washed:v J

earth at elevated pressure, and drying the extruded earth. l

5. A process for improvin the deicolorizing efficiency of Georgia-Floridatype ful'lers earth, which comprises intimately mixing with the'earth from 0.1% to 1.75% by weight, of a watersolubl'e alkaline reagent and sufficient water to give a plastic earth containing from 45% to 60% of water, extruding the plastic earth at elevated pressure, treating the extruded earth with mineral acid an amount sufficient only to neutralize the added. alkaline reagent, water washing the treated earth to remove soluble salts,- adjusting the water content at the washed earth toa value between 45% and 60%, extrudingrthe .washed 7 earth at elevated pressure,- and drying the extruded earth.

- 6. YA proees for improving the decolorizing efficiency of Georgia-Florida type: fullers earth,

which comprises intimately mixing with the earth- 1.%' by weight of sodium hydroxide and suificient water to give a plastic earth containing from 52 to 56% of water, extruding the plastic earth at elevated pressure, treating the extruded earth with sulfuric acid in an amount sufiicient only to neutralize the added sodium hydroxide, water washing the treated earth to remove solublesalts, adjusting the water content ofthe washed. earth to a valuebetween 52% to 56%, extruding the washed earth at elevated pressure, and drying the from 0.1% to. 1.75% by weight of a water s'oluble alkaline reagent and suffici'ent water togive a plastic;earth containing from 45% to '60%' of water, extruding the plastic earth at elevated pressure, drying the'extrudedi earth, treating the dried earth with mineral acid in an amcunt' sufficient, ronly' to neutralize the added alkaline reagent, water washing the neutralized earth to remove soluble salts adjusting the water content of the washed earth to a value between 45%- and 60%, extruding the washed earth at elevated pressure, and drying. the extruded earth.

8. A process for improving the decolorizinget ficiency of Georgia-Florida type frullers earth, which comprises intimately mixing with the earth 1% by weight of sodium hydroxide and sufficient water to give a plastic earth containing from 52%- to 56% of water, extruding the plastic earth at elevated pressure, drying the extruded earth, treating the dried earth with sulfuric acid in an amount sufficient only to neutralize the added sodium hydroxide, water washing the neutralized earth to remove soluble salts, adjusting the water content of the washed earth tc a value between 52% to 56 extruding the washed earth at elevatedpressure, and dryiln-gtheextruded earth.

9. A process for improving the decolorizingef ficiency' of 'Georgia-l' l'orida type fullers earth, which comprises intimately mixing with the earth from 0.1% to 1.75% by weight of a water-soluble alkaline reagent and sufficient water togive a plastic earth containing from 45% to 60% 'of 7 water, extruding the plastic earth at elevated pressure, drying the extruded earth, calcining the dried earth at 800 F. to 1200 treating the calcined earth with mineral acid in an amount suificient only to neutralize the added alkaline. reagent, water washing the neutralized earth to remove soluble salts, and drying the washed'earth...

10. A process for improving the decolorizi'ngefficiency of Georgia-Florida type 'iullers earth, which comprises intimately mixing with the earth 1% by weight of sodium hydroxide and sufficient water to give a plastic earth containing irom.5.2%f

to 56 of water, extruding the plastic earth at elevated pressure,drying the extruded earth, calcining the dried earth at 800 F. to 1200 F.,-tr'eating the calcined earth with sulfuric acid in an amount suflicient only to neutralize the added sodium hydroxide, water washing the neutralized earth to remove soluble salts-wand drying the washed earth.

WILLIAM S. W. McCAR'I-ERZ;

REFERENCES 01th!) The following referenlces are of record in the file of this patent: I V

UNITED STATES PATENTS Name Date La- Lande Nov. 28, 1944 Number