Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M159/00—Lubricating compositions characterised by the additive being of unknown or incompletely defined constitution
  • C10M159/12—Reaction products
  • C10M159/20—Reaction mixtures having an excess of neutralising base, e.g. so-called overbasic or highly basic products
  • C10M159/22—Reaction mixtures having an excess of neutralising base, e.g. so-called overbasic or highly basic products containing phenol radicals

Definitions

• the present invention relates generally to processes for manufacturing overbased sulfurized alkaline earth metal alkylphenates in which an alkaline earth metal base, sulfur, and an alkylphenol are first reacted in the presence of a mutual solvent to form a sulfurized metal phenate intermediate, following which the intermediate is overbased via carbonation in the presence of additional alkaline earth metal base.
• the invention concerns a batch process in which throughput is substantially increased by conducting the carbonation step in a single stage in which CO2 is introduced to the reaction vessel concurrently with the introduction of alkaline earth metal base at a prescribed mole ratio of CO2 to metal base.
• Lubricating oils tend to deteriorate under normal conditions encountered in present day diesel and automotive engines. Sludge, lacquer and resinous materials can form and adhere to engine parts, especially piston rings, grooves and skirts which can have a harmful effect on engine efficiency, operation and useful life.
• additives are incorporated in lubricating oils to reduce the formation of such materials or to keep them suspended so that engine parts are kept clean and operating properly. Additives which reduce the tendency of lubricating oils to form oxidation products are called antioxidants, while additives which tend to suspend oxidation products and sludges, or cleanse the engine parts of such products, are called detergents or dispersants. It is not uncommon for certain additives to exhibit both antioxidant and detergency properties.
• Overbased sulfurized alkaline earth metal alkylphenates have been found to be especially useful for the dual purpose of providing oxidation inhibition and detergency in a lubricating oil.
• overbased refers to the fact that the phenate material incorporates a large excess of alkaline earth metal base over that necessary to neutralize the phenate.
• an overbased phenate will have a TBN (total base number) of about 100-400.
• TBN total base number
• Such high basicity which enables the additive to neutralize harmful acids formed in engine combustion, is accomplished using a well known technique usually referred to as carbonation or carbonate overbasing. This technique generally involves formation of an initial alkaline earth metal sulfurized phenate intermediate having relatively low levels of metal base. This intermediate is then treated with a large excess of additional alkaline earth metal.
• the sulfurized metal phenate intermediate is reacted with the excess metal base in a suitable solvent, usually a glycol, by subjecting the reactants to blowing with gaseous carbon dioxide.
• a suitable solvent usually a glycol
• the CO2 treatment, or carbonation results in the formation of a fine colloidal dispersion whereby the excess metal base is essentially "dissolved.”
• batch processing has the major disadvantage that, as would be expected, much less product can be manufactured over a given period of time than would be the case if one used a continuous process. Nevertheless, a very significant advantage in batch processing is that the degree or extent of carbonation can be very closely and reliably controlled. This is important because overcarbonating or undercarbonating the overbased phenate can result in serious problems.
• Overcarbonated product generally shows poor water tolerance in lubricant formulations and is hazy due to break up of the colloidal dispersion mentioned above. Undercarbonated product tends to have increased viscosity, poor filterability, and resists glycol stripping. Batch processing avoids these problems and, in particular, is the method of choice if a water tolerant phenate is a critical objective.
• Continuous processing has the advantage of maximizing production throughput.
• a first reactor is used to carry out formation of the initial sulfurized metal phenate intermediate while a second reactor or a series of successive reactors are used for carbonation.
• a well-known phenomenon associated with continuous processes is that of residence time distribution. This phenomenon is particularly detrimental in the carbonation step of continuous phenate processes because it results in the formation of both overcarbonated and undercarbonated phenate. For this reason, overbased phenates prepared in continuous processes generally elicit significantly poorer water tolerance than batch prepared phenates.
• the residence time distribution phenomenon can be minimized by increasing the number of reactors used for the carbonation step to approximate a plug flow reactor, but not without substantial capital outlay.
• Belgium Patent No. 876,119 discloses a process for manufacturing a sulfurized overbased alkaline earth metal alkylphenate in which formation of a sulfurized metal phenate intermediate is achieved by contacting a Group II metal base, alkylphenol, and a mutual solvent in a heat exchanger for a time sufficient to form a metal phenate and then passing the phenate without substantial cooling into a reaction zone where said metal phenate is contacted at reaction conditions with sulfur to form the sulfurized metal phenate.
• This intermediate can then undergo carbonation with CO2.
• the patent refers to "semi batch" processes where reactants are added to a reaction vessel while reaction is occurring, the patent fails to teach or suggest the unique measures adopted in the present invention with respect to carbonation.
• a general object of the present invention is to provide a batch process for preparing overbased metal phenate having improved production throughout without at the same time incurring the disadvantages associated with continuous processing.
• Other objects will be apparent herein-after to those skilled in the art.
• the present invention is a process for preparing an overbased sulfurized alkaline earth metal alkylphenate which comprises the steps of: (a) contacting at reaction conditions in a reaction vessel a mixture comprising an alkylphenol, sulfur, a promoter solvent, and an alkaline earth metal base to form a sulfurized alkaline earth metal alkylphenate; followed by (b) overbasing the sulfurized alkaline earth metal alkylphenate formed in (a) above by charging simultaneously to said reaction zone and reacting therein under reaction conditions (i) alkaline earth metal base (ii) promoter solvent and (iii) carbon dioxide at a mole ratio of carbon dioxide to alkaline earth metal base of about 0.40:1 to about .95:1 and at a controlled rate not substantially greater or less than the rate at which the carbon dioxide, alkaline earth metal base, and sulfurized alkaline earth metal phenate undergo reaction; and (c) upon completion of said charging of alkaline earth metal compound and promoter solvent to the reaction zone, allowing said carbon dioxide
• the invention is further directed to a process for preparing an overbased sulfurized alkaline earth metal alkylphenate which comprises the steps of: (a) passing a mixture consisting essentially of alkaline earth metal base and alkylphenol in a mole ratio of about 0.1:1 to about 1.0:1 through pre-heating means into a reaction vessel such that said mixture enters the reaction vessel pre-heated to a temperature of from about 280° to 380°F; while simultaneously charging about 0.1 to about 1.0 moles of a promoter solvent per mole of alkylphenol into the reaction vessel; followed by (b) charging into the reaction vessel about 1.0 to about 2.0 moles of sulfur per mole of alkylphenol over a period of about 20-180 minutes, while maintaining the reaction vessel at a reaction temperature of about 280-380°F; (c) upon completion of the sulfur charge, allowing the contents of the reaction vessel to interact at said reaction temperature for a period of time sufficient to form a sulfurized alkaline earth metal alkylphenate
• the method of carbonation used in the process significantly reduces the reaction cycle time so that the process can approach or equal the production throughput of a continuous process.
• a further reduction in reaction cycle time can be achieved if, as required in the above related embodiment, the sulfurization step utilizes a preheating means to introduce the alkylphenol and metal base into the reaction vessel at the temperature of reaction as opposed to charging them at ambient temperature and waiting for the reactor to heat up to the desired reaction temperature.
• Overbased phenates prepared using the process of the present invention elicit excellent water tolerance properties usually associated with batch processing even though the process can reduce the reaction cycle time of a typical 9 to 10 hour batch reaction by as much as 4 to 5 hours.
• the process of the present invention can be carried out in a single commercial size stirred tank reactor in two stages.
• a sulfurized alkaline earth metal alkylphenate intermediate is formed by contacting under reaction conditions a suitable alkylphenate, an alkaline earth metal base, and sulfur in the presence of a promoter or mutual solvent.
• the sulfurized metal phenate intermediate undergoes treatment with CO2 gas in the presence of an additional amount of alkaline earth metal base and promoter solvent.
• an alkylphenol, an alkaline earth metal base and sulfur are reacted in the presence of a promoter solvent to form a sulfurized metal phenate.
• the alkylphenols useful in the present invention are of the formula R(C6H4)OH where R is a straight chain or branched chain alkyl group having from 8 to 40 carbon atoms and preferably from 10 to 30 carbons, and the moiety (C6H4) is a benzene ring.
• R is a straight chain or branched chain alkyl group having from 8 to 40 carbon atoms and preferably from 10 to 30 carbons, and the moiety (C6H4) is a benzene ring.
• suitable alkyl groups are octyl, decyl, dodecyl, tetradecyl, hexadecyl, etc.
• the alkaline earth metal base can be a base of calcium, barium, magnesium and strontium. Preferred are calcium and magnesium.
• the most commonly used bases are the oxides and hydroxides of the above metals such as calcium oxide, calcium hydroxide, barium oxide, barium hydroxide, magnesium oxide, and the like.
• Calcium hydroxide, commonly called hydrated lime is most commonly used in the manufacture of sulfurized calcium phenates, and it is preferred to use hydrated lime of good quality (relatively free of carbonates) which has not deteriorated during storage.
• the promoter solvent also sometimes referred to as a mutual solvent, can be any stable organic liquid which has appreciable solubility for both the alkaline earth metal base, the alkylphenol, and the sulfurized metal phenate intermediate.
• suitable solvents are glycols and glycol monoethers such as ethylene glycol, 1,4-butane diol, derivatives of ethylene glycol, such as monomethyl ether, monoethyl ether, etc.
• the vicinal glycols are preferred and ethylene glycol is most preferred because it serves to activate the neutralization reaction and to that extent typifies a catalyst, although the exact characteristics describing its function are unknown.
• the sulfur used in the reaction is elemental sulfur. In the present invention it has been found desirable to use molten sulfur.
• sulfonates suitable for use are, e.g., the sulfonic acid salts of molecular weight preferably of more than 400 obtained by sulfonating alkyl-benzenes derived from olefins or polymers of C2 to C4 olefins of chain length C15-C80 and alkaline earth metals such as calcium, barium, magnesium etc.
• a low base calcium sulfonate prepared from a polypropene of about C-60 chain length was included in the sulfurization reaction.
• the lubricating oil can be any lubricating oil that is used in the final lubricating oil formulation containing the phenate prepared by the present invention such as a 5W, 10W or 40W oil, including naphthenic base, paraffin base and mixed based mineral oils.
• a 5W oil is generally most suitable as a reaction diluent.
• the amount of diluent oil is generally about 200 to 300 grams per mole of alkylphenol.
• the amount of low base sulfonate (if used) is about 10-20 grams per mole of alkylphenol.
• the reaction to form the sulfurized alkaline earth metal alkylphenate is carried out in the present invention by contacting the alkaline earth metal base, the alkylphenate, the promoter solvent, the lubricating oil diluent, and the optional low base sulfonate at a reaction temperature of about 280° to about 380°F, preferably about 320° to about 360°F for sufficient time to form the desired intermediate, normally about 40 to 80 minutes.
• the alkylphenol and alkaline earth metal base are preferably charged to the reactor across a preheater set at the desired reaction temperature while simultaneously the promoter solvent is charged to the reaction vessel separately. It is preferred not to charge the glycol solvent across the preheater with the Ca(OH)2 and alkylphenol because the glycol will form a complex (calcium glycol oxide) which will plug up the preheater, typically a heat exchanger.
• the sulfur is added to the reaction mixture at a sufficiently slow rate to control the reaction exotherm and off-gas evolution. Slow sulfur addition (over a period of 30-60 minutes) is particularly important if the alkylphenate and metal base have been charged to the reaction vessel preheated.
• carbonate overbasing can be achieved according to the present invention by adding more alkaline earth metal base and promoter solvent to the reaction vessel while simultaneously carbonating with CO2 gas.
• the range of reaction stoichiometry for the carbonation is as follows: Range Preferred Range Ca(OH)2, mol/mol DDP* 0.5-2.0 1.0-1.5 Glycol, mol/mol DDP 0.5-2.0 1.0-1.5 CO2, mol/mol DDP 0.5-2.0 1.0-1.5 *Dodecylphenol
• the alkaline earth metal base, promoter solvent, and CO2 are charged to the reaction vessel simultaneously at a mole ratio of CO2 to alkaline earth metal base of about .40:1 to about .95:1 and at a controlled rate such that the rate of charging the reactants is not substantially greater or less than the rate at which the carbonation reaction can proceed. If the rate is substantially faster than the speed at which the carbonation can occur the reaction mixture will become very viscous it will be difficult to conduct the carbonation due to formation of glycol oxide complexes, and the resulting product will generally be poorer in quality. If the rate of charging is substantially slower than the rate at which the carbonation reaction can occur the reaction cycle time is unnecessarily prolonged.
• a suitable rate for charging of the alkaline earth metal in the form of a 480 TBN Ca(OH)2 slurry in 5W oil
• a suitable rate for the glycol charge is about 10-15 lbs per minute
• a suitable CO2 charge rate is about 7000 SCFH.
• the mole ratio at which the CO2 and alkaline earth metal base are charged to the reaction vessel during the carbonation step constitutes a critical feature of the present invention. If the mole ratio of CO2 to metal base being charged is below about .40 the reaction mixture will become too viscous and difficult to process, and the resultant product will have poor quality as evidenced by water intolerance. At mole ratios greater than .95 there is a danger of forming overcarbonated product which will result in a hazy phenate product also characterized by poor water tolerance properties.
• a preferred charge ratio of CO2 to alkaline earth metal is about .75 to .85:1.
• the carbonation reaction can be conducted in the temperature range of about 300° to about 360°F and preferably from about 330° to about 350°F.
• the alkaline earth metal base in 5W oil
• the alkaline earth metal base is charged to the reaction across a preheater set at the desired reaction temperature for the carbonation.
• the overbased product can be stripped to remove unreacted glycol and alkylphenol. This is typically done under vacuum with a nitrogen purge at 400° to 480°F. After stripping the product is filtered to remove fine solids.
• overbased sulfurized phenates prepared according to the present invention are suitable as detergent/antioxidant additives for lubricating oils, particularly those used in marine diesel engines.
• an overbased sulfurized alkaline earth metal alkylphenate is prepared using a batch method. Eighty gallons of 5W oil were charged into a commercial 3000 gallon stirred tank reactor. Into the reactor was then charged 7300 lbs of a 180 TBN calcium hydroxide dodecylphenol slurry. This slurry was previously prepared by combining 1700 gallon of dodecylphenol containing about 5.0 wt.% of an alkaline earth metal sulfonate with 1740 lbs of Ca(OH)2 and 1 quart of a commercially obtainable silicone antifoamant, to result in a slurry having a TBN (total base number by ASTM D-2896) of 180.
• TBN total base number by ASTM D-2896
• the 480 TBN slurry of calcium hydroxide in 5W oil was previously prepared by mixing 1240 gallons of 5W, 1 quart of antifoam, and 4140 lbs of Ca(OH)2 in a suitable holding tank. Following the charge of the 480 TBN slurry and additional glycol the entire reaction mixture was nitrogen stripped with 2000 SCFH N2. After nitrogen stripping the reaction mixture was carbonated with 7000 SCFH CO2 until completion of the carbonation as indicated by a sharp increase in the reactor off-gas. Upon completion of the first carbonation stage a second carbonation stage was undertaken by introducing a second charge (3260 lbs) of the 480 TBN calcium hydroxide/5W oil slurry and ethylene glycol (510 lbs) into the reactor, followed by nitrogen stripping.
• the reaction mixture was again carbonated with 7000 SCFH CO2 until completion of the carbonation as evidenced by a sharp increase in off-gas breakthrough.
• the reaction product was then stripped in a conventional manner to remove unreacted glycol and alkyphenol and then filtered to remove solid particles.
• the final product had the following inspection: calcium (wt.%) 9.4; sulfur (wt.%) 3.0; glycol (wt.%) 0.1; carbonate C (wt.%) 1.7; TBN (mg. KOH/g) 267; PM Flash (°F) 356; viscosity (cSt at 100°C) 151; BS&W (Vol. %) 0.02.
• sulfurized overbased calcium phenate was prepared in a continuous process utilizing two 3000 gallon reactors in series.
• the final product had the following inspection: Calcium (wt.%) 9.4; Sulfur (wt.%) 3.2; Glycol (wt.%) 0.1; Carbonate C (wt.%) 1.3; TBN (Mg KOH/g) 254; PM Flash (°F) 350; Viscosity (cSt at 100°C) 275; BS&W (Vol.%) ⁇ 0.05.
• an overbased sulfurized calcium dodecylphenate was prepared in accordance with the present invention.
• Into a commercial 3000 gallon stirred tank reactor was charged 80 gallons of 5W oil.
• Seven thousand three hundred lbs of a 180 TBN calcium hydroxide dodecylphenol slurry (refer to the slurry preparation in Example I, above) was charged into the reactor through a preheater set at 330°F in order to raise the temperature of the slurry to 330°F just prior to its introduction to the reaction vessel.
• 728 lbs of ethylene glycol were charged into the reactor.
• Molten sulfur was then charged to the reaction vessel at rate of 29 lbs per minute until a total of 1150 lbs were charged.
• Example III reduced the reaction cycle time by 225 to 285 minutes. This significant reduction is made possible by the novel and non-obvious manner in which the sulfurization and carbonation steps are carried out in the batch process of the present invention.
• the two stage carbonation required in the batch process of Example I is obviated in the present invention by conducting carbonation at the same time that the 480 TBN Ca(OH)2/5W oil slurry and glycol are being charged to the reactor.
• This feature of the invention circumvents the problem of high viscosity in the batch reaction mixture, which problem necessitates a two stage carbonation as used in Example I, while avoiding the problem of over- or undercarbonation associated with a continuous process such as that described in Example II, which problem results in water tolerance difficulties in the phenate product.
• Example II A comparison was made of the water tolerance of the overbased phenate prepared in Example II (continuous process) with the water tolerance of the overbased phenate prepared by the present invention in Example III.
• Conventional treat levels of the two phenates were incorporated into a standard commercial lubricant formulation containing a major proportion of lube oil and a minor effective amount of ashless dispersant, low base calcium sulfonate, high base magnesium sulfonate, an oxidation inhibitor and zinc dialkyldithiophosphate.
• the water tolerance of the standard formulation containing the Example II overbased phenate was compared to the standard formulation containing the Example III overbased phenate by measuring haze and sediment in samples of the formulation after six weeks of storage at either 70°F or 130°F and at three different levels of water (0.10, 0.15, and 0.20 wt.%) in the formulation. Thus, for each overbased phenate six separate samples of the standard formulation were tested. The results of the water tolerance tests are summarized in Table II, below.
• Example III results in an overbased phenate having significantly improved water tolerance than the phenate produced in the continuous process of Example II.
• the process of the present invention can significantly increase the throughput of a batch process while at the same time accomplishing the excellent water tolerance properties normally associated with a batch preparation.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1993
  • 1993-11-18 EP EP19930309190 patent/EP0601721B1/de not_active Expired - Lifetime
  • 1993-11-18 DE DE1993627515 patent/DE69327515T2/de not_active Expired - Fee Related
  • 1993-11-23 CA CA 2109758 patent/CA2109758A1/en not_active Abandoned
  • 1993-11-24 JP JP31575593A patent/JP3513771B2/ja not_active Expired - Fee Related

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