US3929625A

US3929625A - Shale oil purification

Info

Publication number: US3929625A
Application number: US494679A
Authority: US
Inventors: Roy N Lucas
Original assignee: Petrolite Corp
Current assignee: Baker Petrolite LLC
Priority date: 1972-07-10
Filing date: 1974-08-02
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30

Abstract

This specification discloses a process for removing predominantly inorganic solids from shale oil produced by the high-temperature retorting of oil shale. A surface active chemical aid (a polyoxyalkylene derived nonionic polymeric surfactant) is intermixed with the shale oil. Then, water in the amount between 10 and 30 volume percent of the shale oil is dispersed throughout the shale oil. The resulting dispersion is resolved in an electric field into a purified shale oil phase and an aqueous phase carrying the removed solids. Examples of the chemical aid are oxypropylated, oxyethylated, polyethylene amine and oxypropylated, oxyethylated butyl phenol formaldehyde resin.

Description

United States Patent 1 Lucas Dec. 30, I975 [73] Assignee: Petrolite Corporation, St. Louis,

[22] Filed: Aug. 2, 1974 [21] Appl. No.: 494,679

Related U.S. Application Data [63] Continuation of Ser. No. 270,343, July 10, 1972, abandoned, which is a continuation of Ser. No. 742,549, July 5, I968, abandoned.

[S2] U.S. Cl 208/188; 208/11 3,331,765 7/1967 Canevari et al 208/l88 Primary ExaminerDelbert E. Gantz Assistant Examine'rG. J. Crasanakis Attorney, Agent, or Firm-Emil J. Bednar; Hyman F.

Glass [57] ABSTRACT This specification discloses a process for removing predominantly inorganic solids from shale oil produced by the high-temperature retorting of oil shale. A surface active chemical aid (a polyoxyalkylene derived nonionic polymeric surfactant) is intermixed with the shale oil. Then, water in the amount between 10 and 30 volume percent of the shale oil is dispersed throughout the shale oil. The resulting dispersion is resolved in an electric field into a purified shale oil phase and an aqueous phase carrying the removed solids. Examples of the chemical aid are oxypropylated, oxyet'hylated, polyethylene amine and oxypropylated, oxy' thylated butyl phenol formaldehyde resin.

9 Claims, No Drawings SHALE OIL PURIFICATION This application is a continuation application of my copending application Ser. No. 270,343, filed on July 10, 1972, now abandoned, which was a continuation application of my application Ser. No. 742,549, filed on July 5, 1968, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the purification of shale oil. More particularly, it relates to the removal of predominantly inorganic solids from shale oil.

2. Description of the Prior Art Vast amounts of hydrocarbonous raw materials are available in oil shale deposits which are a mineral resource found in many areas of the world. The oil shale contains a solid organic material which can be thermally decomposed into a fluid hydrocarbonous product, namely shale oil. The processing of the oil shale into shale oil is commonly termed retorting.

Shale oil, as a pyrolytic product, is similar in hydrocarbon content to thermally cracked petroleum products. However, the shale oil also contains a high content of non-petroleum derivatives. For example, 50 percent or more of the shale oil compounds include one or more nitrogen, sulfur, or oxygen atoms per molecule.

Furthermore the shale oil contains many polymerizable materials, namely unsaturated hydrocarbons (olefins). These substances react with one another, or with other reactants, to form gums, high molecular weight polymers, etc., which materials reduce the sales value of the shale oil. These polymeric materials make difficult the ready separation of dispersed materials such as water, solids, etc., from shale oil. Usually, there is only a small amount of water in the shale oil. However, water forms stable emulsions with the shale oil, and also causes other undesired results.

The shale oil usually contains a small amount, e.g., about 26% by weight, of suspended particles which are predominantly inorganic solids. These solids are generated during the retorting of oil shale whether effected in situ or in surface retorts. These particles may vary in amount depending upon the source of the oil shale and the retorting process which produces the shale oil. The dispersion of the solids within the shale oil appears to be stabilized by the polymerizable compounds and water present therein. Thus, these solids are carried with the shale oil into refining operations.

Established shale oil refining procedures generally involve a combination of distillation, catalytic hydrogenation, and various phase separation procedures whereby shale oil is converted into a variety of useful hydrocarbon products. The shale oil may be hydrogenated by passing it over a suitable catalyst in the presence of hydrogen. The solids in the shale oil interfere with such refining procedure by coating and clogging Removing the solids from shale oil with conventional procedures was unsuccessful. For example, a 50% reduction in solids could be accomplished by water washing and centrifuging the shale oil at 10,000 rpm for 15 minutes. The addition of sodium carbonate (a powerful wetting agent) had marginal effect upon the removal of solids. The solids could be dramatically reduced only by employing high dilutions in a solvent, and then centrifuging of the diluted shale oil for extended periods of time. Such procedures obviously are commercially unacceptable.

Attempts were made to remove the solids from shale oil by employing an electric treater wherein an electric field caused coalescence of connate water and/or coagulation of the dispersed solids. Additional water was dispersed within the shale oil in the hopes that by coalescing electrically the resulting dispersion, substantial amounts of the solids would be removed from the shale oil with the water phase. The electric treater produced only a small and unsatisfactory reduction in the amount of solids in the shale oil carrying only connate water. The electric treater was electrically stable but did experience a high current demand. Addition of water in amounts of between 10 and 30 volume percent to the shale oil produced no detectable improvement in the removal of soilds. Moreover, the treater was overloaded electrically in such operation. The addition of powerful wetting agents, and conventional oil soluble demulsifiers (surfactants) to the shale oil did not produce any difference in the results obtained in the electric treater. No improvement in removing solids could be obtained by variations in temperature, electrical gradients, or spacings between the electrodes which defined the electric field in the treater. It was concluded from these results that conventional techniques in using the electric treater were incapable of acceptably removing solids from shale oil.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a process for removing predominantly inorganic solids from shale oil which comprises dispersing water into said shale oil in the presence of a surface active chemical aid, and resolving electrically the resulting dispersion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be practiced upon shale oil obtained by any suitable retorting procedure from oil shale. The retorting may take place in situ, or from mined oil shale in surface retorts. The shale oil usually contains only small amounts of dispersed connate water, e.g., l% by volume. Additionally, the shale oil usually contains predominantly inorganic solids in a small amount, e.g., 2% by weight. The exact amounts of the water and solids may vary somewhat depending upon the shale oil and how it is retorted, but there figures are believed typical of shale oil.

The present process can be practiced in any suitable apparatus. For example, the apparatus illustrated in US. Pat. No. 2,387,250 can be employed for this purpose. With such apparatus, the shale oil is passed from a retort through coolers and suitable piping to an electric treater. The liquid shale oil is mixed with the surface active chemical aid. Also, the shale oil is mixed with fresh water. The chemical aid and water can be intimately mixed with the shale oil by suitable mixers such as weight-loaded mixing valves. The resultant dispersion is passed into the electric treater wherein the dispersion is resolved or coalesced electrically into a purified shale oil phase and an aqueous phase which contains the removed solids.

The construction and operation of the electric treater is not critical to the present process. It needs only to provide a suitable electric field and phase separating conditions in which a water and oil dispersion may be coalesced into separate oil and water phases. For example, electrode spacings which define the electric field in the treater can vary between about 3 and about ll inches. The electric potential applied to these electrodes can vary the gradient of the electric field between about l,000 and about 10,000 volts per inch. The magnitude of the gradient or the applied potential within the electric treater was not found to be critical to the practice of the present process.

The chemical aid and water may be added to the shale oil in any order. Improved results are obtained when the chemical aid is present in the shale oil before introduction of the water. Better results are obtained when the chemical aid is introduced into the shale oil immediately after the retorting operation and when the shale oil is at a temperature which does not destroy the effectiveness of the chemical aid. Additional improvement in results occurs when the water is dispersed into meric surfactant. Ethylene oxide and propylene oxide derived nonionic polymeric surfactants are a well recognized class in surface chemistry. Many memebers of this class have been employed for producing surface active effects.

It is well known that alkylene oxides will react with any material containing an active hydrogen. The product of this reaction is an alcohol which obviously contains an active hydrogen. Therefore, it will react further to form eventually a water-soluble alkyloxy chain, which is hydrophillic. If the initialmaterial is a hydrophobic polymeric compound of suitable molecular weight, a surface active compound having a certain hydrophobic-hydrophillic property occurs after a sufficient number of alkyloxy groups have been added. In the present process, the initial material is a hydrophobic polymeric compound having a molecular weight from about ISO to about 1,500. Alkylene oxides are condensed, or reacted, with this initial material until the resulting product has a molecular weight ranging from about 800 to 27,000.

Propylene oxide may be condensed with a polyfunctional compound, such as a polyalkylamine, to form the initial material, a polymer. Then, the polymeric initial material is reacted with sufficient ethylene oxide to give the desired molecular weight range and resulting surfactant characteristics. Thus, the polyoxyalkylene derived nonionic polymeric surfactants employed in the present process may be characterized as being formed ofa relatively high-molecular weight polymeric initial materials which are reacted with alkylene oxides until surfactant properties are obtained at molecular weights of about 800 or greater.

One surface active chemical aid which has been found especially suitable for the present process is oxypropylated, oxyalkylated, polyethylene amine. The

compound is prepared by reacting polyethylene amine with polypropylene oxide to give four polyoxypropylene branches. Polyoxyethylene is then added on all four branches until the molecular weight falls within the range of betweenabout 800 to about 27,000. The resultant surfactant is found to be useful in the present process.

Other polyoxyalkylene derived nonionic polymeric surfactants may be used. Among these surfactants, whichare of good utility in the present process, are the oxyalkylated alkyl phenol formaldehyde resins. The alkyl substituent can be butyl or heavier groups; but not heavier than octyl groups. Examples of the alkyl substituents are the butyl, amyl, hexyl heptyl and octyl radicals and their isomers. Particular polymer surfactants of this group which have been found to give good results in the present process are: oxypropylated, oxyethylated butyl phenol formaldehyde resin; oxyethylated amyl phenol formaldehyde resin; diglycolic ester of oxypropylated, oxyethylated butyl phenol formaldehyde resin; and a mixture of oxyethylated amyl phenol formaldehyde resin, ammonium dinonyl phenol sulfomate, and acylated alkanolamine. These surface active chemical aids, and methods for their preparation, may be more readily appreciated by reference to U.S. Pat. Nos. 2,499,365-6-7-8; 2,598,234.

Other usable surface active chemical aids presently in existence and to be developed in the future, can be readily selected from an inspection of the properties of the specifically mentioned members of the polyoxyalkylated nonionic polymeric surfactants. It is therefore, not only impossible to attempt a comprehensive catalog of such composition, but to attempt to describe the invention in its broader aspect in terms of specific chemical names of these compounds would be too voluminous and unnecessary since one skilled in the art could, by following the description of the present invention, herein select a useful surface active chemical aid. This, invention lies in the use of suitable surface active chemical aids in a process employing an electric field of effective voltage to remove solids from shale oil. The surface active chemical aids are important only in the sense that their properties can effect this function. To precisely define each specific useful chemical aid in light of the present disclosure would merely call for chemical knowledge within the skill of the art in a manner anologous to a mechanical engineer who prescribes in the construction of a machine the proper materials and the proper dimensions thereof. For the description in this specification and with the knowledge of a chemist, one will know or deduce with confidence the applicability or specific chemical aids suitable for this inventive process by applying them in the process set forth herein. In anology to the case of a machine, wherein the use of certain materials of a construction or dimension of parts would lead to no practical useful .result, various surface active compounds will be reemployed in the present process.

The utility of the present invention was carefully evaluated in the laboratory and in the field. In the laboratory, a test procedure was derived for testing the effectiveness of the present process. Mixing facilities were provided wherein the surface active chemical aid, or water, or both, could be mixed into the shale oil. The resulting mixture of dispersion was introduced continuously into a pilot plant electric treater which provided an electric field with a gradient of about 5 kilovolts per inch and facilities to remove separately purified shale oil and aqueous phases. The shale oil was adjusted in temperature to 200F. The dispersion was passed through the electric treater at a relatively constant flow of conventional rate magnitude. The surface active chemical aid was employed in amounts of 300 ppm. Water was intermixed at by volume into the shale oil.

The shale oil was passed in one run through the laboratory equipment without the addition of a chemical aid or water. The electric treater exhibited acceptable electric characteristics but removed only of the solids from the shale oil. Then, 20% by volume of water was added into the shale oil (but no surface active chemical aid). The resulting dispersion was passed through the electric treater. The electric treater did not remove any solids from the shale oil. It exhibited overloaded electrical characteristics in this run. The same run was repeated with the addition of sodium silicate (a powerful wetting agent) in an attempt to remove solids. No significant change in the result was obtained. Next, a surface active chemical aid (diglycolic ester of oxypropylated, oxyethylated butyl phenol formaldehyde resin) was mixed at 300 ppm with the shale oil. Then, 20% by volume of fresh water was dispersed into the shale oil. The resulting dispersion was passed into the electric treater for its resolution electrically. The solids content of the purified shale oil was analyzed. Analysis indicated a 93% removal of the solids from the shale oil. The electrical behavior of the treater was acceptable.

ln view of the outstanding performance in laboratory tests of the present process, it was decided to compare the purified shale oil obtained from the present process with that which could be obtained by mechanical separation means. Shale oil samples were subjected to extensive depth filtration and dilution-centrifugation techniques in an extreme attempt to remove as large a portion of the solids as possible. Shale oil samples were ashed before and after such mechanical separations and compared to the purified shale oil samples obtained from the present process. The results indicated that approximately one-fifth of the solids present in the shale oil were too fine and they could not be removed by mechanical extraction means. However, the present process removed these solids completely.

Subsequent tests in the laboratory were conducted on another sample of shale oil to define the surface active compounds which, as chemical aids, would produce the desired results of the present process. The

tests were conducted in the aforedescribed manner.

TABLE I Solids Removal Surface Active Chemical Aid (Wt.)

Oxyethylated, amyl phenol formaldehyde resin 90 Diglycolic ester of oxypropylated oxyethylated butyl phenol formaldehyde resin 90 Oxypropylated, oxyethylated polyethyleneamine 90 Oxyethylated amyl phenol formaldehyde resin, ammonium dinonyl phenol sulfonate, and acylated alkanolamine 8O Oxyethylated, oxypropylated butyl phenol formaldehyde resin 90 Oxypropylated, oxyethylated butyl phenol formaldehyde resin A field test of the present process was conducted to determine the effect of large scale operations on its procedural aspects. The equipment used in these field tests closely resembled that shown in US. Pat. No. 2,387,250. However, planar energized and grounded horizontal electrodes were used. The electric treater operated under substantially the same electrical characteristics as the laboratory unit. The present process consistently reduced the solids content of the shale oil by at least by weight. These tests did show that it was advantageous to add the surface active chemical aid to the shale oil as soon as possible after being produced in the retort. However, the shale oil should not be at such elevated temperature as to cause deterioration of the surfactant. Additionally, the water added to the shale oil containing the chemical compound should be added immediately before the resulting dispersion is passed into the electric treater.

The amounts of the surface active chemical aid mixed into the shale oil were found uncritical. The amounts ranged from about 10 ppm up to 500 ppm without apparent change in result. Similarly, the amount of water dispersed into the shale oil could vary from 10 to 30% by volume without effecting the removal of solids. The water amount usually should be at least four times the weight of the solids to be removed from the shale oil. The water may be fresh water from wells, or other natural source, and may contain various substances as long as these substances do not interfere with the functioning of the water in removing solids in the present process.

The operation in the present process of the surface active chemical aids could not be determined with certainty from the information presently available. The following explanation is proffered but this invention should not be limited thereby. Shale oil contains many chemical compounds having active bonding sites that, with time and suitable environment, promote polymerization and other combining reactions which create high molecular weight aggregates. These aggregates form preferentially around high energy sites such as the dispersed solids in the shale oil. The presence of water causes polymerization reactions to become more rapid. Thus, mixing water into shale oil produces a rapid polymerization and as a result, refractory dispersions are formed which have a high electrical conductivity. Thus, these dispersions cannot be successfully coalesced with the electric treater. Additionally, the high molecular weight aggregates produced by polymerization have a density greater than water. Therefore, the aggregates make extremely difficult a separation of the shale oil 7 phase from the aqueous phases. The chemical aids of the present invention act to inhibit accelerated polymerization reactions in the shale oil. These chemical aids promote transfer of the inorganic solids from the shale oil into the aqueous phase during coalescence within the electric treater. Also, they reduce the amount of polymeric water-proofing that thesolids acquire by adsorption of the high molecular weight aggregates. Thus, it appears that the chemical aids employed in the present process inhibit polymerization and agglomeration of polymeric materials within the oil shale, especially in the presence of water.

From the foregoing, it will be apparent that there has been herein described aprocess for removing solids from shale oil which is especially effective. Various changes and alterations may be made in the practice of this process by those skilled in the art without departing from the spirit of the invention. It is intended that such changes be included within the scope of the appended claims. The present description is intended to be illustrative and not limitative of the present invention.

What is claimed is: 1. A process for separating a stable dispersion of suspended predominantly inorganic solids from shale oil produced by retorting oil shale, which process comprises l. dispersing water in amounts sufficient only to form a shale oil-continuous dispersion into said shale oil containing a surface active chemical aid, 'said chemical aid having been added to said shale oil immediately after said shale oil had been retorted from oil shale and at a shale oil temperature not destructive to said chemical aid, said chemical aid comprising a polyoxyalkylene derived nonionic polymeric surfactant, said surfactant being derived from a nonionic polymeric precursor which is a polymeric hydrophobic compound with an active hydrogen reactable with alkylene oxides and having a molecular weight from about 150 to 1,500

. and being selected from the group consisting of polyethylene amine and alkyl phenol formaldehyde resins wherein said alkyl group has four to eight carbon atoms; said precursor being reacted .with said alkylene oxide to form said polymeric surfactant, said surfactant having a molecular weight from about 800 to about 27,000 and 2. then immediately resolving electrically said shale oil-continuous dispersion to coalesce said dispersion into (a) a shale oil phase with reduced inorganic solids content and (b)-an aqueous phase containing said inorganic solidsremoved from said shale oilphase.

2. The process of claim 1 wherein said amounts of water sufficient only to form a shale. oil-continuous dispersion are between 10 and 30 volume percent of said shale oil.

3. The process of claim 1 wherein said amounts of water sufficient only to form a shale oil-continuous dispersion are at least four times the weight of the solids to be removed from said shale oil.

4. The process of claim 1 wherein said surface active chemical aid is selected from the group consisting of polyoxyalkylene derivatives of alkyl phenol formaldehyde resins and polyethylene amine polymers, and mixtures thereof.

5. The process of claim 1 wherein said surface active chemical aid is a polyoxyalkylene derivative of said alkyl phenol formaldehyde resin wherein the alkyl substituent is selected from the group of butyl, amyl, hexyl, heptyl andoctyl radicals, and their isomers.

6. The process of claim 1 wherein said surface active chemical aid is selected from the group consisting of oxypropylated, oxyethylated butyl phenol formaldehyde resin, oxypropylated, oxyethylated polyethylene amine, oxyethylated amyl phenol formaldehyde resin, oxyethylated oxypropylated butyl phenol formaldehyde resin, and mixtures thereof.

7. The process of claim 1 where the electrical resolu- 'tion of the shale oil-continuous dispersion takes place upon the application of an electric potential to the electrodes of'between about 1,000 and about 10,000 volts per inch.

I 8. The process of claim 7 where the space between the electrode can vary between about 3 and about ll inches.'

9.. The process of claim 6 wherein the oxyethylated amyl phenol formaldehyde resin surface active chemical aid comprises a mixture of oxyethylated amyl phenol formaldehyderesin, ammonium dinonyl phenol sulfonate, and acylated alkanolamine.

Claims

1. A PROCESS FOR SEPARATING A STABLE DISPERSION OF SUSPENDED PREDOMINANTLY INORGANIC SOLIDS DRFROM SHALE OIL PRODUCED BY RETORTING OIL SHALE, WHICH PROCESS COMPRISES

1. DISPERSING WATER IN AMOUNTS SUFFICIENT ONLY TO FORM A SHALE OIL-CONTINUOUS DISPERSION INTO SAID SHALE OIL COMTAINING A SURFACE ACTIVE CHEMICAL AID, SAID CHEMICAL AID HAVING BEEN ADDED TO SAID SHALE OIL IMMEDIATELY AFTER SAID SHALE OIL HAD BEEN RETORTED FROM OIL SHALE AND AT A SHALE OIL TEMPERATURE NOT DESTRUCTED TO SAID CHEMICAL AID, SAID CHEMICAL AID COMPRISING A POLYOXYALKYLENE DERIVED NONIONIC POLYMERIC SURFACTANT, SAID SURFACTANT BEING DERIVED FROM A NONIONIC POLYMERIC PRECURSOR WHICH IS A POLYMERIC HYDROPHOBIC COMPOUND WITH AAN ACTIVE HYDROGEN REACTABLE WITH ALKYLENE OXIDES AND HAVING A MOLECULAR WEIGHT FROM ABOUT 150 TO 15,00 AND BEING SELECTED FROM THE GROUP CONSISTING OF POLYETHYLENE AMINE AND ALKYL PHENOL FORMALDEHYDE RESINS WHEREIN SAID ALKYL GROUP HAS FOUR TO EIGHT CARBON ATOMS, SAID PRECURSOR BEING REACTED WITH SAID ALKYLENE OXIDE TO FORM SAID POLYMERIC SURFACTANT, SAID SURFACTANT HAVING A MOLECULAR WEIGHT FROM ABOUT 800 TO ABOUT 27,000 AND

2. The process of claim 1 wherein said amounts of water sufficient only to form a shale oil-continuous dispersion are between 10 and 30 volume percent of said shale oil.

2. then immediately resolving electrically said shale oil-continuous dispersion to coalesce said dispersion into (a) a shale oil phase with reduced inorganic solids content and (b) an aqueous phase containing said inorganic solids removed from said shale oil phase.

5. The process of claim 1 wherein said surface active chemical aid is a polyoxyalkylene derivative of said alkyl phenol formaldehyde resin wherein the alkyl substituent is selected from the group of butyl, amyl, hexyl, heptyl and octyl radicals, and their isomers.

7. The process of claim 1 where the electrical resolution of the shale oil-continuous dispersion takes place upon the application of an electric potential to the electrodes of between about 1,000 and about 10,000 volts per inch.

8. The process of claim 7 where the space between the electrode can vary between about 3 and about 11 inches.

9. The process of claim 6 wherein the oxyethylated amyl phenol formaldehyde resin surface active chemical aid comprises a mixture of oxyethylated amyl phenol formaldehyde resin, ammonium dinonyl phenol sulfonate, and acylated alkanolamine.