NO160493B - CATALYST MATERIALS INCLUDING METAL CHELAT AND A QUARTER OF AMMONIUM HALOGENIDE COMPOUND FOR OXYDATION OF MERCAPTAN IN SOUR PETROLEUM DISTILLATE. - Google Patents

Description

This invention relates to a catalyst material comprising a metal chelate and a quaternary ammonium halide compound for the oxidation of mercaptan in acidic petroleum distillate.

The invention is a further development of the invention according to patent no. 157 588 (application no. 790618; explanatory document no. 157 588 ), which relates to a method for sweetening a mercaptan-containing, acidic petroleum distillate, whereby the distillate is brought into contact with a support deposited nitrogenous catalyst, preferably a metal phthalocyanine catalyst on a carbon support, under oxidizing conditions, in the presence of a quaternary ammonium halide, preferably containing at least one alkyl radical with 12-18 carbon atoms, and in the presence of an alkali metal hydroxide, the reaction being carried out in the presence of a quaternary ammonium halide with structural formula:

where R is a hydrocarbon radical containing up to 20 carbon atoms and selected from alkyl, cycloalkyl, aryl, aralkyl and alkaryl, R' is a predominantly straight-chain alkyl radical containing from 5 to 20 carbon atoms, and X is chlorine, fluorine, bromine or iodine, the quaternary ammonium halide is used in an amount of from 0.001 to 1 mol per moles of the alkali metal hydroxide.

With the present invention it is now provided

a catalyst material for oxidation of mercaptans contained in an acidic petroleum distillate, comprising a metal chelate-mer-captan oxidation catalyst, preferably a metal phthalocyanine catalyst, deposited on a solid adsorbing support material, which catalyst material is suitable for use in the method described in the above paragraph. The catalyst material is characteristic in that a quaternary ammonium compound of the general formula is also deposited on the carrier material

where R is a hydrocarbon radical containing up to 20 carbon atoms and is selected from alkyl, cycloalkyl, aryl, alkaryl and aralkyl, R^ is a predominantly straight-chain alkyl radical containing from 5 to 20 carbon atoms, R2 is aryl, alkaryl or aralkyl, and X is chlorine, bromine, iodine or fluorine,

which quaternary ammonium compound constitutes from 1 to 50% by weight, preferably from 5 to 35% by weight, of the catalyst material.

The metal chelate mercaptan oxidation catalyst used as a component of the catalyst material according to the invention,

may be any of the many metal chelates known in the art to be effective in catalyzing the oxidation of mercaptans contained in an acidic petroleum distillate to form polysulfide oxidation products. These chelates include the metal compounds of tetrapyridinoporphyrazine described in US. patent document no. 3 980 582, such as e.g. cobalt tetrapyridino porphyrin sulfonate, porphyrin and metalloporphyrin catalysts described in US Patent No. 2,966,453, such as e.g. cobalt tetraphenylporphyrin sulfonate; corrin catalysts described in US. patent document no. 3 255 892, such as e.g. cobalt corrin sulfonate; and organometallic chelate catalysts described in US. U.S. Patent No. 2,918,426, as the condensation product of an aminophenol and a Group VIII metal. Metal phthalocyanines constitute a preferred class of metal chelate mercaptan oxidation catalysts.

The metal phthalocyanines used as mercaptan oxidation catalysts include magnesium phthalocyanine, titanium phthalocyanine, hafnium phthalocyanine, vanadium phthalocyanine, tantalum phthalocyanine, molybdenum phthalocyanine, manganese phthalocyanine, iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, platinum phthalocyanine, palladium phthalocyanine, copper phthalocyanine, zinc phthalocyanine, and tin phthalocyanine. Cobalt phthalocyanine and vanadium phthalocyanine are particularly preferred. The metal phthalocyanines are most often used in the form of derivatives. The commercially available sulfonated derivatives, such as e.g. cobalt phthalocyanine monosulfonate, cobalt phthalocyanine disulfonate and mixtures thereof are particularly preferred. The sulfonated derivatives can be prepared, e.g. by reaction of the phthalocyanine of cobalt, vanadium or other metal with fuming sulfuric acid. Although the sulphonated derivatives are preferred, it will be understood that other derivatives, especially the carboxylated derivatives, can also be used. The carboxylated derivatives can be easily prepared by the action of trichloroacetic acid on the metal phthalocyanine.

In the above formula for the quaternary ammonium compound, R 1 is preferably an alkyl radical of from 12 to 18 carbon atoms, while R 2 is preferably benzyl and X is preferably chlorine.

Preferred quaternary ammonium compounds thus include quaternary ammonium chlorides such as benzyldimethyldodecylammonium chloride, benzyldimethyltetradecylammonium chloride, benzyldimethylhexadecylammonium chloride, benzyldimethyloctadecylammonium chloride and the like. Andre egnede kvartære ammoniumforbindelser er fenyldialkylpentylammoniumklorid, fenyldialkylhexylaimoniumklorid, fenyl-dialkyloctylammoniumklorid, fenyldialJ<yldecylammoniumklorid, fenyldialkyl-dodecylammoniumklorid, fenyldialkyltetradecylammoniumklorid, f ényldialkylhexadecylammoniumklorid, f enyldialkyloctadecylammonium.-klorid, fenyldialkyleicosylammoniumklorid, nafthyldialkyl<p>entyl-ammoniumklorid, nafthyldialkylhexylammoniumklorid, nafthyldialkyl-octylammoniumklorid, nafthyldialkyldecylammoniumklorid, nafthyl-dialkyldodecylammoniumklorid, nafthyldialkyltetradecylammonium-klor id, nafthyldialkylhexadecylammoniumklorid,nafthyldialkyl-octadecylammoniumklorid, benzyldialkylpentylammoniumklorid, benzyldialkylhexylammoniumklorid, benzyldialkyloctylammoniumklorid, benzyldialkyldecylammoniumklorid, benzyldialkyleicosylammonium-klorid, tolyldialkyloctylammoniumklorid, tolyldi-alkyldecylammoniumklorid, tolyldialkyldodecylammoniumkorid, tolyl-dialkyltetradecylammoniumklorid, tolyldialkylhex adecylammonium chloride, tolyldialkyloctadecylammonium chloride, tolyldialkyleicosylammonium chloride, diphenylalkylpentylammoniumuitichloride, diphenylalkylhexylammonium chloride, diphenylalkyloctylammonium chloride, diphenylalkyldecylammonium chloride, diphenylalkyldodecylammonium chloride, diphenylalkyltetradecylammonium chloride, diphenylalkylhexadecylammonium chloride, diphenylalkyloctadecylammonium chloride, diphenylalkyloctadecylammonium chloride, and similar fluorides.

ides and iodides, as the alkyl radical or radicals which in-

goes in the above-mentioned compounds is selected from methyl,

ethyl and propyl.

The preferred benzyldimethylalkylammonium chlorides are marketed by Mason Chemical Company under the trademark "Maquats".

The mentioned benzyldimethylalkylammonium chlorides can, however, be prepared according to a method during which ammonia is first reacted with a C12~<C>18<c>arboxYlic acid 1 contact with silica gel at approx. 500°C, whereby a C3_2~<c>i8 nitrile is obtained. The nitrile is then reduced with hydrogen in contact with a nickel catalyst at approx. 140°C. The obtained C. --C.„ amine is separated from reaction

Liz laughed

the mixture and reacted with an excess of methyl chloride of 2 mol. After neutralization of the reaction mixture, the amine is reacted with 1 mol equivalent of benzyl chloride, whereby the desired benzyldimethylalkylammonium chloride is obtained. Both methyl chloride and benzyl chloride can conveniently be reacted with the amine in methanolic solution at a temperature of approx. 150°C. The product can be used in the form it is obtained, or it can be further treated with activated charcoal to remove contaminants.

The solid, adsorber-ende carrier material used in connection with the present catalysts can be any of the well-known, solid adsorber-ende materials which are commonly used as carrier materials for catalysts. Pre-

drawn adsorberendé materials include the various carbonization products (hereinafter referred to as "charcoal") which are produced by destructive distillation of wood, peat, lignite, nut shells, bones and other carbonaceous material, and preferably such wood-

coal that has been heat-treated and/or chemically treated to form a highly porous particle structure with increased adsorption capacity. These are usually referred to as activated carbon or activated charcoal. The aforementioned adsorber materials also include the naturally occurring clays and silicates, e.g. diatomaceous earth, calcareous earth, diatomaceous earth, attapulgite clay, feldspar, montmorillonite, halloysite and kaolin, as well as naturally occurring or

synthetically produced refractory inorganic oxides, such as aluminum oxide, silicon dioxide, zirconium dioxide, thorium oxide and boron oxide or combinations thereof, such as silicon dioxide-aluminium oxide, silicon dioxide-zirconium dioxide and aluminum oxide-zirconium dioxide.

In each specific case, the solid, adsorbing material is selected on the basis of its properties under the conditions under which it is to be used. For example, the solid, absorbent carrier material for use in the treatment of acidic petroleum distillates as described above must be insoluble and largely inert to the petroleum distillate under the alkaline reaction conditions that prevail in the treatment zone. In the latter case, charcoal, and especially activated charcoal, is preferred because of its capacity for metal phthalocyanine adsorption and because of its stability under the treatment conditions. The quaternary ammonium compounds used according to the invention, and likewise metal chelate mercaptan oxidation catalysts, especially the metal phthalocyanines, are easily adsorbed on the solid adsorbing support material. The quaternary ammonium salt can make up up to 50% by weight of the catalyst material. In the sweetening process which is explained at the outset, the quaternary ammonium salt will suitably constitute from 1 to 50% by weight, preferably from 5 to 35% by weight, of the catalyst material. Typically, the solid, adsorbing support material can adsorb up to 25% by weight of metal phthalocyanine and still provide a stable catalyst material. A smaller amount in the range of 0.1 to 10% by weight usually forms a suitable active catalyst material, while ranges of 0.1 to 2% by weight are usually preferred. The advantage in terms of increased activity obtained by using metal phthalocyanine concentrations higher than 2% by weight has not so far justified the use of higher concentrations. Due to the significant increase in activity achieved by using ay the quaternary ammonium salt in accordance with invention combined with minimal amounts of metal phthalocyanine, however, it is believed that the higher concentrations will be effective in promoting a further increase in the rate of mer-can<p>tanoxidation, especially with regard to the acidic petroleum distillates which are difficult to process.

The quaternary ammonium compound and the metal chelate may be deposited on the solid adsorbent support in any conventional manner or by means of methods which may otherwise prove appropriate. The components can be deposited on the support simultaneously from a common aqueous or alcoholic solution and/

or dispersion, or they can be deposited separately, regardless of order. The impregnation process can be carried out using conventional techniques whereby the carrier material in the form of spheres, pills,<p>ellets, granules or other particle forms of uniform or non-uniform shape and size is soaked, suspended or immersed one or more times in an aqueous or alcoholic impregnation solution and /or dispersion for adsorbing a given amount of the ammonium compound and the metal chelate compound. A preferred method involves the use of a rotary dryer with a steam jacket. The adsorbing carrier material is immersed in the impregnation solution and/or dispersion contained in the dryer, and the carrier material is tumbled in this as a result of the rotary movement of the dryer. Evaporation of the solution in contact with the drummed support material is accelerated by supplying steam to the steam jacket. In any case, the resulting catalyst material is allowed to dry either at ambient temperature, at elevated temperature in an oven or in a stream of hot gases or in any other suitable manner.

An alternative and suitable method for adsorbing the ammonium compound and the metal chelate compound on the solid, adsorber-ende carrier consists of placing the adsorber-ende carrier material in advance as a stationary layer in the zone or chamber for treating the acidic petroleum distillate and then

passes the impregnation solution and/or dispersion of the ammonium compound and the metal chelate through the layer to form the catalyst material in situ. This method makes it possible to re-circulate the solution and/or the dispersion one or more times to achieve a desired concentration of the ammonium compound and the metal chelate on the support material. According to a further alternative method, the adsorbing carrier material can be placed in advance in the treatment zone or chamber and the zone or chamber then filled with the impregnation solution and/or dispersion to thereby wet the carrier material for a predetermined time.

In the method for sweetening an acidic petroleum desalt where the catalyst material is to be used, the catalyst material is used together with an alkali metal hydroxide, e.g. sodium hydroxide in aqueous solution. The solution can further contain a solubilizing agent to promote the solubility of the mercaptan, e.g. an alcohol, especially methanol, ethanol, propanol or isopropanol and likewise phenols or cresols.

A particularly preferred alkaline reagent is an aqueous caustic solution containing from 2 to 30% by weight of sodium hydroxide. When a solubilizing agent is used, this is preferably methanol, and the alkaline solution can conveniently contain from 2 to 100% by volume thereof. Sodium hydroxide and potassium hydroxide are the preferred alkaline reagents, but others, including lithium hydroxide, rubidium hydroxide and cesium hydroxide, can also be used with advantage.

The method by which the catalyst material according to the invention is to be used can be carried out under the treatment conditions known in the art. The process is usually carried out at normal ambient temperatures, although higher temperatures of up to 105°C can also be used. Pressures up to 69 atmospheres can be used, although atmospheric pressure or pressure substantially equal to atmospheric pressure is fully satisfactory. Contact times corresponding to a fluid space velocity per hours of from 0.5 to 10 or more are effective in achieving a desired reduction of the mercaptan content in an acidic petroleum distillate. The optimum contact time depends on the size of the treatment zone, the amount of catalyst contained therein and the nature of the distillate being treated.

As previously indicated, the sweetening of the acidic petroleum distillate is carried out by oxidation of its mercaptan content to disulphides. Accordingly, the method is carried out in the presence of an oxidizing agent, preferably air, although oxygen or another oxygen-containing gas can also be used. The acidic petroleum ether distillate can be fed up or down through the catalyst layer. The acidic petroleum distillate can contain a sufficient amount of entrained air, but usually air is added which is mixed with the distillate and supplied to the treatment zone together with this. In some cases, it can be advantageous to supply the air separately to the treatment zone and in countercurrent to the similarly separately supplied distillate.

The catalyst material according to the invention is both active and stable. Consequently, the catalyst material can be used in a stationary layer for the treatment of large volumes of acidic petroleum distillates, especially those distillates that contain the more difficult-to-oxidize mercaptans. As previously mentioned, the catalyst material's quaternary ammonium compound and metal phthalocyanine are easily adsorbed on the solid, adsorber-ende carrier component. If, therefore, some proportion of the quaternary ammonium compound or the metal phthalocyanine should eventually be leached from the carrier and transferred into the reactant stream, this can easily be replaced in situ in the catalyst material by adding one or both components to the freshening process, e.g. in mixture with an alkaline reagent to be adsorbed on the solid adsorbent support in the treatment zone.

The following example illustrates a preferred embodiment of the invention.

Example

For the production of the catalyst material according to the invention, an impregnation solution and/or dispersion was formed by adding 0.75 g of cobalt phthalocyanine monosulfonate and 23.5 g of a 50% alcoholic solution of dimethylbenzylalkylammonium chloride to 250 ml of deionized water in a rotary, steam-heated inlet evaporator. Benzyldimethylalkylammonium chloride consisted of benzyldimethyldodecylammonium chloride. 250 ml particles of activated charcoal of size 10-30mesh (Tyler) were immersed in the impregnation solution and tumbled in this for 1 hour by the rotary motion in the evaporator. Steam was then supplied to the steam jacket of the evaporator, and the impregnation solution was evaporated to dryness in contact with the tumbled charcoal particles for 1 hour.

The catalyst material thus produced, which is referred to below as Catalyst A, was compared with a "standard" catalyst. The "standard" catalyst, referred to below as Catalyst B, was prepared essentially as described but without the benzyldimethylalkylammonium chloride component.

The equalization test consisted of treating an acidic kerosene stream which was passed down through 100 ml of catalyst arranged in a stationary bed in a vertical tube reactor. The kerosene was supplied at a liquid space velocity per hour of 0.5 under 3.4 atmospheres of air, which was sufficient to provide approx. 1.5 times the stoichiometric amount of air required to oxidize the mercaptans in the kerosene. In each of the cases, the catalyst layer was first moistened with 10 ml of an 8% aqueous sodium hydroxide solution, 10 ml of this solution being added to the catalyst layer at 12 hour intervals, mixed with the supplied kerosene. The treated kerosene, which originally contained 533 ppm mercaptan sulphur, was periodically analyzed for mercaptan sulphur. The mercaptan sulfur content of the treated kerosene was plotted against the number of hours in operation, whereby a curve was obtained from which the data listed in the table below was extracted.

Claims (1)

Catalyst material for the oxidation of mercaptans contained in an acidic petroleum distillate, comprising a metal chelate mercaptan oxidation ion catalyst, preferably a metal phthalocyanine catalyst, deposited on a solid adsorber end carrier material, according to NO pat.nr:157,588, characterized in that a quaternary ammonium compound of the general formula is also deposited on the carrier material where R is a hydrocarbon radical containing up to 20 carbon atoms and is selected from among alkyl, cycloalkyl, aryl, alkaryl and aralkyl, R^ is a mainly straight-chain alkyl radical containing from 5 to 20 carbon atoms, R is aryl, alkaryl or aralkyl, and X is chlorine, bromine, iodine or fluorine, which quaternary ammonium compound constitutes from 1 to 50% by weight, preferably from 5 to 35% by weight, of the catalyst material.