Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G75/00—Inhibiting corrosion or fouling in apparatus for treatment or conversion of hydrocarbon oils, in general
  • C10G75/04—Inhibiting corrosion or fouling in apparatus for treatment or conversion of hydrocarbon oils, in general by addition of antifouling agents
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
  • C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
  • C10G9/16—Preventing or removing incrustation
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/192—Macromolecular compounds
  • C10L1/198—Macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds homo- or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon to carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid
  • C10L1/1983—Macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds homo- or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon to carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid polyesters

Definitions

• the present invention relates to a process for reducing fouling by liquid hydrocarbons during the processing thereof at relatively high temperatures, for example in refinery operations.
• hydrocarbons such as crude oil and intermediates in mineral oil processing, for example, but also petrochemicals and petrochemical intermediates, are generally heated to temperatures between 100° C. and 550° C., frequently between 200° C. and 550° C.
• hydrocarbons used as heat carriers are exposed to such temperatures.
• hydrocarbons used form unwanted breakdown products or by-products at elevated temperatures, which can separate out and accumulate at the hot surfaces of the heat transferers.
• the crude oils used for that purpose generally comprise constituents which lead to deposits, for example alkali metal and alkaline earth metal salts, compounds or complexes containing transition metals, for example iron sulfide or porphyrins, sulfur compounds, for example mercaptans, nitrogen compounds, for example pyrroles, compounds containing carbonyl groups or carboxyl groups, and polycyclic aromatics, for example asphaltenes and/or coke particles.
• the hydrocarbons used for processing virtually always contain small amounts of dissolved oxygen.
• fouling The deposits which form in the course of processing of the hydrocarbons at elevated temperatures and settle out on the surfaces in contact with the liquid are referred to as fouling. They form particularly on the hot insides of pipes, machines or heat exchangers.
• deposits are usually higher molecular weight materials, the consistency of which may range from tar through rubber and “popcorn” to coke.
• the composition thereof may differ in nature and in many cases defies any detailed analysis. They often contain a combination of carbonaceous phases which are coke-like in nature, polymers and/or condensates which are formed from the hydrocarbons or impurities present therein by various mechanisms. Further deposit constituents are frequently salts composed primarily of magnesium chloride, calcium chloride and sodium chloride.
• the formation of polymers and/or condensates is attributed to catalysis by metal compounds, for example compounds of copper or iron, which are present as impurities in the hydrocarbons to be processed.
• Metal compounds of this kind can, for example, accelerate the hydrocarbon oxidation rate by promoting degenerative chain branching.
• the free radicals formed can in turn trigger oxidation and polymerization reactions, which leads to the formation of resins and sediments.
• relatively inert carbonaceous deposits are enclosed by more adhesive condensates or polymers.
• Fouling deposits are equally encountered in the petrochemical field, where petrochemicals are either produced or purified.
• the deposits in this environment are primarily polymeric in nature and have a severe effect on the economic viability of the petrochemical operation.
• the petrochemical operations include, for example, the preparation of ethylene or propylene, or else the purification of chlorinated hydrocarbons.
• Fouling is also observed in the processing of biogenic raw materials, for example in the processing of fatty acids and derivatives thereof, for example fatty acid esters.
• oil-soluble, polar nitrogen compounds are used in many cases. These are predominantly reaction products of alkyl- or alkenylsuccinic acids or anhydrides thereof with polyamines, which are optionally derivatized further.
• U.S. Pat. No. 3,271,295 discloses reaction products of alk(en)ylsuccinic anhydrides with polyamines for prevention of deposits on metal surfaces in heat transferers in mineral oil refining.
• WO-2011/014215 discloses the use of mono- and bisimides formed from polyamines and C 10 - to C 800 -alkyl- or -alkenylsuccinic anhydrides for prevention of deposits in plants for mineral oil refining.
• U.S. Pat. No. 5,342,505 discloses the use of reaction products formed from poly(alkenyl)succinimides with epoxyalkanols as antifoulants in liquid hydrocarbons during the processing thereof at elevated temperatures
• U.S. Pat. No. 5,171,420 discloses reaction products formed from alkenylsuccinic anhydrides, polyols, amines bearing hydroxyl groups, polyalkylenesuccinimides and polyoxyalkyleneamines for prevention of deposits in the course of heating of liquid hydrocarbons.
• polyfunctional reagents which lead to highly branched structures are used.
• the reaction products of dicarboxylic acids with polyamines typically have a relatively low molecular weight, since dicarboxylic acids, when condensed with primary amines, react preferentially to give imides and form only minor proportions, if any, of diamides.
• the condensation is restricted to the reaction of the primary amino groups of the polyamine with one dicarboxylic acid each, such that the result is typically molecular weights of not more than 3000 g/mol. Higher molecular weight compounds, which are desirable for the efficient reduction of fouling, are thus not obtainable in this way.
• EP-0809623 discloses oligomeric and polymeric bisesters of alkyl- or alkenyldicarboxylic acid derivatives and polyalcohols, and the use thereof as solubilizers, emulsifiers and/or wash-active substances.
• Preferred polyalcohols are glycerol and oligomeric glycerols.
• WO-2008/059234 discloses oligo- and polyesters based on alk(en)ylsuccinic anhydrides and polyols having at least 3 hydroxyl groups and the use thereof as emulsifiers. These polymers are additionally useful in the oilfield as foaming agents in foam drilling fluids, as kinetic gas hydrate inhibitors and as lubricants in aqueous drilling fluids.
• U.S. Pat. No. 4,216,114 discloses condensation products of C 9-18 -alkyl- or -alkenylsuccinic anhydrides with water-soluble polyalkylene glycols and polyols having at least 3 OH groups and the use thereof for splitting water-in-oil emulsions.
• U.S. Pat. No. 3,447,916 discloses condensation polymers of alkenylsuccinic anhydrides, polyols and fatty acids for lowering the pour point of hydrocarbon oils. In these polymers, the hydroxyl groups of the polyol are very substantially esterified.
• DE-A-1920849 discloses condensation polymers of alkenylsuccinic anhydrides, polyols having at least 4 OH groups and fatty acids for lowering the pour point of hydrocarbon oils.
• the stoichiometry of the reactants used for the condensation is selected such that the number of moles of OH groups and carboxylic groups is the same, meaning that there is substantially complete esterification.
• WO-2011/076338 discloses low-temperature additives for middle distillates comprising polycondensates of a polyol containing two primary OH groups and at least one secondary OH group with a dicarboxylic acid or anhydride thereof or ester thereof bearing a C 16 - to C 40 -alkyl radical or a C 16 - to C 40 -alkenyl radical.
• the invention accordingly provides for the use of a polyester which bears hydroxyl groups and is preparable by polycondensation of a polyol containing two primary OH groups and at least one secondary OH group with a dicarboxylic acid or anhydride thereof or ester thereof which bears a C 16 - to C 400 -alkyl radical or a C 16 - to C 400 -alkenyl radical as an antifoulant in the thermal treatment of liquid hydrocarbon media within the temperature range from 100 to 550° C.
• the present invention further provides a method for reducing fouling in a liquid hydrocarbon medium during the thermal treatment of the medium at temperatures between 100 and 550° C., in which a polyester which bears hydroxyl groups and is preparable by polycondensation of a polyol containing two primary OH groups and at least one secondary OH group with a dicarboxylic acid or anhydride thereof or ester thereof which bears a C 16 - to C 400 -alkyl radical or a C 16 - to C 400 -alkenyl radical is added to the liquid hydrocarbon before and/or during the thermal treatment.
• the invention further provides a method for increasing the service life of plants for thermal treatment of liquid hydrocarbon media within the temperature range from 100 to 550° C., in which a polyester which bears hydroxyl groups and is preparable by polycondensation of a polyol containing two primary OH groups and at least one secondary OH group with a dicarboxylic acid or anhydride thereof or ester thereof which bears a C 16 - to C 400 -alkyl radical or a C 16 - to C 400 -alkenyl radical is added to a liquid hydrocarbon medium to be processed in the plant before and/or during the thermal treatment.
• the polyester bearing hydroxyl groups is generally obtained by the polycondensation of a dicarboxylic acid bearing a C 16 - to C 400 -alkyl radical or -alkenyl radical, also referred to collectively hereinafter as C 16 -C 400 -alk(en)yl radical, with the primary hydroxyl groups of the polyol. It is preferable that the secondary OH groups remain essentially unesterified.
• the preferred structure of the polyester bearing hydroxyl groups can thus be represented, for example, by formula (A):
• Preferred dicarboxylic acids which bear C 16 -C 400 -alkyl- and/or -alkenyl radicals and are suitable for preparation of the polyesters A) bearing hydroxyl groups correspond to the formula (1)
• one of the R 1 to R 4 radicals is a C 16 -C 400 -alkyl- or -alkenyl radical, one is a methyl group and the rest are hydrogen.
• one of the R 1 to R 4 radicals is a C 16 -C 400 -alkyl- or -alkenyl radical and the others are hydrogen.
• R 5 is a C—C single bond. More particularly, one of the R 1 to R 4 radicals is a C 16 -C 400 -alkyl- or -alkenyl radical, the other R 1 to R 4 radicals are hydrogen and R 5 is a C—C single bond.
• the dicarboxylic acids or anhydrides thereof bearing alkyl- and/or -alkenyl radicals can be prepared by known processes. For example, they can be prepared by heating ethylenically unsaturated dicarboxylic acids with olefins or with chloroalkanes. Preference is given to the thermal addition of olefins onto ethylenically unsaturated dicarboxylic acids or anhydrides thereof (“ene reaction”), which is typically conducted at temperatures between 100 and 250° C.
• the dicarboxylic acids and dicarboxylic anhydrides bearing alkenyl radicals which are formed can be hydrogenated to dicarboxylic acids and dicarboxylic anhydrides bearing alkyl radicals.
• Dicarboxylic acids and anhydrides thereof preferred for the reaction with olefins are maleic acid and more preferably maleic anhydride. Additionally suitable are itaconic acid, citraconic acid and anhydrides thereof, and the esters of the aforementioned acids, especially those with lower C 1 -C 8 -alcohols, for example methanol, ethanol, propanol and butanol.
• one of the R 1 to R 4 radicals is a linear C 16 -C 40 -alkyl- or -alkenyl radical.
• mixtures of olefins having different chain lengths are used.
• olefins having 18 to 36 carbon atoms for example mixtures of olefins in the C 20 -C 22 , C 20 -C 24 , C 24 -C 28 , C 26 -C 28 , C 30 -C 36 range.
• Olefin mixtures may also comprise minor proportions of shorter- and/or longer-chain olefins compared to the range specified, for example hexene, heptene, octene, nonene, decene, undecene, dodecene, tetradecene and/or olefins having more than 40 carbon atoms.
• the proportion of the shorter- and longer-chain olefins in the olefin mixture is, however, not more than 10% by weight. More particularly, it is between 0.1 and 8% by weight, for example between 1 and 5% by weight.
• Olefins particularly preferred for the preparation of the dicarboxylic acids or anhydrides thereof bearing C 16 -C 40 -alk(en)yl radicals have a linear or at least substantially linear alkyl chain.
• Linear or substantially linear is understood to mean that at least 50% by weight, preferably 70 to 99% by weight, especially 75 to 95% by weight, for example 80 to 90% by weight, of the olefins have a linear component having 16 to 40 carbon atoms and especially having 18 to 36 carbon atoms, for example having 19 to 32 carbon atoms.
• ⁇ -olefins, wherein the C ⁇ C double bond is at the chain end are used.
• Particularly useful olefins have been found to be technical grade alkene mixtures. These contain preferably at least 50% by weight, more preferably 60 to 99% by weight and especially 70 to 95% by weight, for example 75 to 90% by weight, of terminal double bonds ( ⁇ -olefins). In addition, they may contain up to 50% by weight, preferably 1 to 40% by weight and especially 5 to 30% by weight, for example 10 to 25% by weight, of olefins having an internal double bond, for example having vinylidene double bonds having the structural element R 17 —CH ⁇ C(CH 3 ) 2 where R 17 is an alkyl radical having 12 to 36 carbon atoms and especially having 14 to 32 carbon atoms, for example having 15 to 28 carbon atoms.
• paraffins may be present, but preferably not more than 5% by weight.
• one of the R 1 to R 4 radicals is a C 41 -C 400 -alkyl- or -alkenyl radical and especially a C 50 - to C 300 -alkyl or -alkenyl radical, for example a C 55 - to C 200 -alkyl- or -alkenyl radical.
• this alk(en)yl radical is branched.
• these C 41 -C 400 -alk(en)yl radicals derive from polyolefins preparable by polymerization of monoolefins having 3 to 6 and especially having 3, 4 or 5 carbon atoms.
• Particularly preferred monoolefins as base structures for the polyolefins are propylene and isobutene, which give rise to poly(propylene) and poly(isobutene) as polyolefins.
• Preferred polyolefins have an alkylvinylidene content of at least 50 mol %, particularly of at least 70 mol % and especially at least 80 mol %, for example at least 85 mol %.
• Alkylvinylidene content is understood to mean the content in the polyolefins of structural units which result from compounds of the formula (3):
• R 6 or R 7 is methyl, ethyl or propyl and especially methyl and the other group is an oligomer of the C 3 -C 6 -olefin.
• the alkylvinylidene content can be determined, for example, by means of 1 H NMR spectroscopy.
• the number of carbon atoms in the polyolefin is between 41 and 400. In a preferred embodiment of the invention, the number of carbon atoms is between 50 and 3000 and especially between 55 and 200.
• the parent polyolefins of the C 41 -C 400 -alkyl- or -alkenyl radical are obtainable, for example, by ionic polymerization and are available as commercial products (e.g.
• Glissopal® polyisobutenes from BASF with different alkylvinylidene content and molecular weight.
• mixtures of various polyolefins in which case these may differ, for example, in terms of the parent monomers, the molecular weights and/or the alkylvinylidene content.
• Preferred polyesters bearing hydroxyl groups are preparable by reaction of alkyl- or alkenylsuccinic acids and/or anhydrides thereof bearing a C 16 -C 400 -alkyl- or -alkenyl radical with polyols bearing two primary and at least one secondary hydroxyl group.
• Preferred polyols may be monomeric, oligomeric or polymeric in terms of structure. Polymers and oligomers are referred to collectively as polymers.
• R 16 in formula A) is preferably a radical of the formula (2)
• t is a number from 1 to 6
• r and s are each independently a number from 1 to 9
• t+r+s is a number from 3 to 10.
• n in formula A) is 1.
• Preferred monomeric polyols have three to 10 and especially four to six carbon atoms. They additionally have at least one and preferably 1 to 6, for example 2 to 4, secondary OH groups, but not more than one OH group per carbon atom.
• Suitable monomeric polyols are, for example, glycerol, 1,2,4-butanetriol, 1,2,6-trihydroxyhexane, and also reduced carbohydrates and mixtures thereof.
• Reduced carbohydrates are understood here to mean polyols which derive from carbohydrates and bear two primary and two or more secondary OH groups. Particularly preferred reduced carbohydrates have 4 to 6 carbon atoms.
• reduced carbohydrates examples include erythritol, threitol, adonitol, arabitol, xylitol, dulcitol, mannitol and sorbitol.
• a particularly preferred monomeric polyol is glycerol.
• n in formula A) is a number from 2 to 100, preferably a number from 2 to 50, more preferably a number from 3 to 25 and especially a number from 4 to 20.
• Preferred polymeric polyols have six to 150, especially eight to 100 and particularly nine to 50 carbon atoms. They bear at least one, preferably two to 50 and especially three to 15 secondary OH groups, but not more than one OH group per carbon atom.
• Polymeric polyols suitable in accordance with the invention are preparable, for example, by polycondensation of polyols having two primary and at least one secondary OH group.
• a preferred polymeric polyol is poly(glycerol).
• Poly(glycerol) is especially understood to mean structures derivable by polycondensation from glycerol.
• the condensation level of poly(glycerols) preferred in accordance with the invention is between 2 and 50, more preferably between 3 and 25 and especially between 4 and 20, for example between 5 and 15.
• poly(glycerol) is known in the prior art. It can be prepared, for example, via addition of 2,3-epoxy-1-propanol (glycide) onto glycerol.
• poly(glycerol) can be prepared by polycondensation, as known per se, of glycerol.
• the reaction temperature in the polycondensation is generally between 150 and 300° C., preferably between 200 and 250° C.
• the polycondensation of glycerol is normally conducted at atmospheric pressure.
• Catalyzing acids include, for example, HCl, H 2 SO 4 , organic sulfonic acids or H 3 PO 4 ;
• catalyzing bases include, for example, NaOH or KOH.
• the catalysts are added to the reaction mixture preferably in amounts of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the weight of the reaction mixture.
• the polycondensation of glycerol can be conducted without solvent, or else in the presence of solvent. If the polycondensation is effected in the presence of solvent, the proportion thereof in the reaction mixture is preferably 0.1 to 70% by weight, for example 10 to 60% by weight.
• Preferred organic solvents here are the solvents also used and preferred for the condensation of the dicarboxylic acid, anhydride thereof or ester thereof bearing alk(en)yl radicals with the polyol.
• the polycondensation of glycerol generally takes 3 to 10 hours. This process is also applicable mutatis mutandis to the polycondensation of other polyols.
• the dicarboxylic acid, anhydride thereof or ester thereof bearing alk(en)yl radicals are converted to the polyester bearing hydroxyl groups preferably in a molar ratio of 1:2 to 2:1, more preferably in a molar ratio of 1:1.5 to 1.5:1 and especially in a molar ratio of 1:1.2 to 1.2:1, for example in a equimolar ratio. More preferably, the conversion is effected with an excess of polyol. In this context, molar excesses of 1 to 10 mol % and especially 1.5 to 5 mol % based on the amount of dicarboxylic acid used have been found to be particularly useful.
• the polycondensation of the dicarboxylic acid, anhydride thereof or ester thereof bearing alkyl radicals with the polyol is effected preferably by heating C 16 -C 400 -alkyl- or -alkenyl-substituted dicarboxylic acid or the anhydride or ester thereof together with the polyol to temperatures above 100° C. and preferably to temperatures between 120 and 320° C., for example to temperatures between 150 and 290° C.
• Azeotropic removal by means of suitable organic solvents is also suitable for this purpose.
• Preferred solvents for the polycondensation of the dicarboxylic acid, anhydride thereof or ester thereof bearing alk(en)yl radicals with the polyol are relatively high-boiling, low-viscosity solvents.
• Particularly preferred solvents are aliphatic and aromatic hydrocarbons and mixtures thereof.
• Aliphatic hydrocarbons preferred as solvents have 9 to 20 carbon atoms and especially 10 to 16 carbon atoms. They may be linear, branched and/or cyclic. They are preferably saturated or at least substantially saturated.
• Aromatic hydrocarbons preferred as solvents have 7 to 20 carbon atoms and especially 8 to 16, for example 9 to 13, carbon atoms.
• Preferred aromatic hydrocarbons are mono-, di-, tri- and polycyclic aromatics. In a preferred embodiment, these bear one or more, for example two, three, four, five or more, substituents. In the case of a plurality of substituents, these may be the same or different.
• Preferred substituents are alkyl radicals having 1 to 20 and especially having 1 to 5 carbon atoms, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl and neopentyl radical.
• aromatics examples include alkylbenzenes and alkylnaphthalenes.
• aliphatic and/or aromatic hydrocarbons or hydrocarbon mixtures e.g. petroleum fractions, kerosene, decane, pentadecane, toluene, xylene, ethylbenzene or commercial solvent mixtures such as Solvent Naphtha, Shellsol® AB, Solvesso® 150, Solvesso® 200, Exxsol® products, ISOPAR® products and Shellsol® D products, are particularly suitable.
• solvents based on mineral oils solvents based on renewable raw materials and synthetic hydrocarbons obtainable, for example, from the Fischer-Tropsch process, are suitable as solvents.
• the proportion thereof in the reaction mixture is preferably 1 to 75% by weight and especially 10 to 70% by weight, for example 20 to 60% by weight.
• the condensation is preferably conducted without solvent.
• Preferred catalysts are acidic inorganic, organometallic or organic catalysts and mixtures of two or more of these catalysts.
• Acidic inorganic catalysts in the context of the present invention are, for example, sulfuric acid, phosphoric acid, phosphonic acid, hypophosphorous acid, aluminum sulfate hydrate, alum, acidic silica gel and acidic aluminum hydroxide.
• acidic inorganic catalysts are, for example, aluminum compounds of the formula Al(OR 15 ) 3 and titanates of the formula Ti(OR 15 ) 4 , where the R 15 radicals may each be the same or different and are each independently selected from C 1 -C 10 -alkyl radicals, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl or n-decyl, C 3 -C 12 -cycloalkyl radicals, for example cyclopropyl,
• Preferred acidic organometallic catalysts are, for example, selected from dialkyltin oxides (R 15 ) 2 SnO where R 15 is as defined above.
• a particularly preferred representative of acidic organometallic catalysts is di-n-butyltin oxide, commercially available as “oxo-tin” or as the Fascat® brand.
• Preferred acidic organic catalysts are acidic organic compounds having, for example, phosphate groups, sulfo groups, sulfate groups or phosphonic acid groups.
• Particularly preferred sulfonic acids contain at least one sulfo group and at least one saturated or unsaturated, linear, branched and/or cyclic hydrocarbyl radical having 1 to 40 carbon atoms and preferably having 3 to 24 carbon atoms.
• aromatic sulfonic acids and specifically alkylaromatic monosulfonic acids having one or more C 1 -C 28 -alkyl radicals and especially those having C 3 -C 22 -alkyl radicals.
• Suitable examples are methanesulfonic acid, butanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, 2-mesitylenesulfonic acid, 4-ethylbenzenesulfonic acid, isopropylbenzene-sulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, dodecyl-benzenesulfonic acid, didodecylbenzenesulfonic acid and naphthalenesulfonic acid.
• acidic ion exchangers as acidic organic catalysts, for example poly(styrene) resins which bear sulfo groups and have been crosslinked with about 2 mol % of divinylbenzene.
• boric acid for the performance of the process according to the invention, particular preference is given to boric acid, phosphoric acid, polyphosphoric acid and polystyrenesulfonic acids.
• minor amounts of the dicarboxylic acids, anhydrides thereof or esters thereof bearing alk(en)yl radicals are replaced in the reaction mixture by C 1 - to C 18 -monocarboxylic acids, preferably C 2 - to C 16 -monocarboxylic acids and especially C 3 - to C 14 -monocarboxylic acids, for example C 4 - to C 12 -monocarboxylic acids.
• not more than 20 mol % and preferably 0.1 to 10 mol %, for example 0.5 to 5 mol %, of the dicarboxylic acids, anhydrides thereof or esters thereof bearing alk(en)yl radicals is replaced by one or more monocarboxylic acids.
• minor amounts, for example up to 10 mol % and especially 0.01 to 5 mol % of the alk(en)ylsuccinic acids or anhydrides thereof may also be replaced by further dicarboxylic acids, for example succinic acid, glutaric acid, maleic acid and/or fumaric acid. More preferably, the polyesters bearing hydroxyl groups are prepared in the absence of monocarboxylic acids.
• minor amounts of the polyol are replaced in the reaction mixture by C 1 - to C 30 -monoalcohols, preferably C 2 - to C 24 -monoalcohols and especially C 3 - to C 18 -monoalcohols, for example C 4 - to C 12 -monoalcohols.
• C 1 - to C 30 -monoalcohols preferably C 2 - to C 24 -monoalcohols and especially C 3 - to C 18 -monoalcohols, for example C 4 - to C 12 -monoalcohols.
• preferably not more than 20 mol % and more preferably 0.1 to 10 mol %, for example 0.5 to 5 mol %, of the polyol is replaced by one or more monoalcohols.
• the polyesters bearing hydroxyl groups are prepared in the absence of monoalcohols.
• the polyol bearing two primary and at least one secondary hydroxyl groups may also be replaced by one or more diols in minor amounts of up to 10 mol %, for example 0.01 to 5 mol %. Preference is given here to diols, for example ethylene glycol, propylene glycol and/or neopentyl glycol. More preferably, the polyesters bearing hydroxyl groups are prepared in the absence of diols.
• minor amounts of the polyol bearing two primary and at least one secondary OH group are replaced in the reaction mixture by polyols having three or more primary OH groups, for example having four, five, six or more primary OH groups.
• polyols having three or more primary OH groups for example having four, five, six or more primary OH groups.
• preferably not more than 10 mol % and more preferably 0.1 to 8 mol %, for example 0.5 to 4 mol %, of the polyol bearing two primary and at least one secondary OH group is replaced by a polyol having three or more primary OH groups.
• Suitable polyols having three or more primary OH groups are, for example, trimethylolethane, trimethylolpropane and pentaerythritol.
• the mean condensation level of the polyesters bearing hydroxyl groups used in accordance with the invention is preferably between 4 and 200, more preferably between 5 and 150, especially between 7 and 100 and particularly between 10 and 70, for example between 15 and 50, repeat dicarboxylic acid and polyol units.
• the condensation level is understood here to mean the sum of m+p+q as per formula (A).
• the weight-average molecular weight Mw of the polyesters bearing hydroxyl groups, determined by means of GPC in THF against poly(ethylene glycol) standards, is preferably between 2000 g/mol and 600 000 g/mol.
• polyesters which derive from dicarboxylic acids bearing C 16 -C 40 -alk(en)yl radicals it is more preferably between 2000 and 100 000 g/mol and especially between 3000 and 50 000 g/mol, for example between 4000 and 20 000 g/mol.
• polyesters which derive from dicarboxylic acids bearing C 41 -C 400 -alk(en)yl radicals it is more preferably between 3000 and 500 000 g/mol, particularly between 5000 and 200 000 g/mol and especially between 8000 and 150 000 g/mol, for example between 10 000 and 100 000 g/mol.
• the acid number of the polyesters bearing hydroxyl groups is less than 40 mg KOH/g and more preferably less than 30 mg KOH/g, for example less than 20 mg KOH/g.
• the acid number can be determined, for example, by titration of the polymer with alcoholic tetra-n-butylammonium hydroxide solution in xylene/isopropanol.
• the hydroxyl number of the polyesters is between 40 and 500 mg KOH/g, more preferably between 50 and 300 mg KOH/g and especially between 60 and 250 mg KOH/g.
• the hydroxyl number can, after reaction of the free OH groups with isocyanate, be ascertained by means of 1 H NMR spectroscopy, by quantitative determination of the urethane formed.
• the polyesters bearing hydroxyl groups used in accordance with the invention are nitrogen-free.
• “Nitrogen-free” is understood in accordance with the invention to mean that the nitrogen content thereof is below 1000 ppm by weight and more preferably below 100 ppm by weight and especially below 10% by weight, for example below 1 ppm by weight.
• the nitrogen content can be determined, for example, according to Kjeldahl.
• liquid hydrocarbon medium represents various different mineral oil hydrocarbons and petrochemicals.
• mineral oil hydrocarbon feedstocks including crude oils and fractions obtainable therefrom, for example naphtha, gasifier fuel, kerosene, diesel, jet fuel, heating oil, gas oil, vacuum residues inter alia are covered by this definition.
• petrochemicals are olefinic or naphthenic process streams, aromatic hydrocarbons and derivatives thereof, ethylene dichloride and ethylene glycol.
• liquid hydrocarbon media are hydrocarbons used as heat carriers, for example fused and/or substituted aromatics.
• biogenic raw materials and products obtainable from biogenic raw materials by processing, for example animal and vegetable oils and fats and derivatives thereof, for example fatty acid alkyl esters.
• the liquid hydrocarbon media may also comprise constituents not consisting of hydrocarbons, for example salts, minerals and organometallic compounds.
• the polyesters used in accordance with the invention are added to the liquid hydrocarbon media preferably in amounts of 0.5 to 5000 ppm by weight, more preferably of 1.0 to 1000 ppm by weight, for example of 2 to 500 ppm by weight.
• the polyesters may be dispersed or dissolved in the liquid hydrocarbon medium. They are preferably dissolved.
• the polyesters used in accordance with the invention are preferably dissolved or dispersed in a polar or nonpolar organic solvent and added to the liquid hydrocarbon medium as a concentrate.
• Preferred solvents are the solvents and solvent mixtures already mentioned as solvents for the condensation reaction between dicarboxylic acid and polyol. Particular preference is given to aromatic solvents.
• the proportion of the polyester in the concentrate is 5 to 95% by weight, more preferably 10 to 80% by weight and especially 20 to 70% by weight, for example 25 to 60% by weight.
• the polyester is preferably added to the liquid hydrocarbon medium prior to the thermal treatment thereof.
• the addition can be undertaken batchwise, for example into the storage vessel of the liquid hydrocarbon medium, or continuously into the feed line to the heat treatment plant.
• the addition is preferably effected at a site where the temperature of the liquid hydrocarbon medium is at least 10° C. and especially at least 20° C., for example at least 50° C., below the maximum heat treatment temperature.
• it has often been found to be useful to promote the mixing of the polyester into the liquid hydrocarbon medium by means of static or dynamic mixing apparatus.
• polyesters bearing hydroxyl groups Particular advantages are shown by the inventive use of polyesters bearing hydroxyl groups and by the method that utilizes them in the processing or treatment of liquid hydrocarbon media above 100° C., especially between 150 and 500° C. and particularly between 200° C. and 480° C., for example between 250° C. and 450° C.
• polyesters used in accordance with the invention can be used together with one or more further additives.
• Preferred further additives are pour point depressants and demulsifiers, the latter preferably based on alkoxylated alkylphenol-aldehyde resins.
• polyesters bearing hydroxyl groups in the thermal treatment of liquid hydrocarbon media leads to a reduction in fouling superior to the prior art additives and often also to the substantial and in some cases even complete suppression thereof. As a result, the energy requirement in the processing of liquid hydrocarbon is lowered and the throughput of the plant and the yield of target product are increased.
• the method of the invention is generally suitable for reducing and often even for suppressing fouling in the processing of liquid hydrocarbon media at relatively high temperatures. This lowers the energy requirement of the process and increases the throughput of the plant and the yield of target product.
• the reduction in fouling reduces the frequency of maintenance shutdowns for removal of deposits and hence increases the plant availability.
• the methods of the invention have been used successfully for reduction of fouling in crude oil distillation, in the processing of intermediates in mineral oil processing and in the processing of petrochemicals, and also of petrochemical intermediates, for example of gases, oils and reforming feedstocks, chlorinated hydrocarbons and liquid products from olefin plants, for example of bottoms phases from deethanization.
• the methods have likewise been used successfully for reduction and often for suppression of fouling by hydrocarbons used as heating media on the ‘hot side’ of heat exchange systems.
• the suitability of the additives used in accordance with the invention for suppression or at least for reduction of fouling by liquid hydrocarbons in the course of thermal treatment thereof can be measured, for example, with commercially available HLPS (Hot Liquid Process Simulation) systems.
• HLPS Hot Liquid Process Simulation
• the oil to be treated thermally is pumped continuously through a capillary with a heating element present therein.
• deposits gradually form on the heating element which impair heat transfer and lead to a pressure drop over the capillary.
• the extent of fouling can be assessed, for example, via the drop in the temperature at the outlet of the capillary. A significant drop in the temperature during the experiment indicates the occurrence of fouling. Measurements of this kind are generally regarded as a measure for assessment of the tendency of an oil to fouling in heat exchangers.
• the ⁇ -olefins used were commercially available mixtures of 1-alkenes or poly(isobutenes) having the compositions specified.
• the acid numbers were determined by titration of an aliquot of the reaction mixture with alcoholic tetra-n-butylammonium hydroxide solution in xylene/isopropanol.
• the hydroxyl numbers were determined, after reacting the free OH groups of the polymers with isocyanate, by means of 1 H NMR spectroscopy, by quantitative determination of the urethane formed. The values reported are based on the solvent-free polymers.
• the molecular weights were determined by means of lipophilic gel permeation chromatography in THF against poly(ethylene glycol) standards and detection by means of an RI detector.
• HLPS Hot Liquid Process Simulation
• Test oil 1 2 3 Origin Brazil Malaysia Thailand API gravity @ 15° C. 25.7 47.2 11.4 [°API] Viscosity [mPas] 61 5 160 (25° C.) (25° C.) (50° C.) Density [g/cm 3 ] 0.900 0.792 0.990 (20° C.) (20° C.) (16° C.) Pour point [° C.] ⁇ 27 +18 +33 Asphaltene content 7.9 3.2 10.3 [% by wt.]
• the viscosity was determined to ASTM D-445, and the density to DIN EN ISO 12185.
• the pour point was determined to ASTM D-97.
• the asphaltene content was determined to IP 143.
• the decreases in temperature after an experimental duration of 5 hours observed in the experiments using the method of the invention are much smaller than in comparative experiments using other methods or additives. Moreover, higher maximum temperatures are generally observed at first. Both indicate lower deposits on the heating element and hence more efficient suppression of fouling in the case of inventive use of the additives or of the method that utilizes them. Accordingly, the method of the invention entails less frequent maintenance of the plant for removal of the deposits and hence longer service lives of the plant. Since the target oil temperature is often preset in industrial plants, the method of the invention additionally leads to saving of energy.

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• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Health & Medical Sciences (AREA)
• Emergency Medicine (AREA)
• Polyesters Or Polycarbonates (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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