Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/38—Separation; Purification; Stabilisation; Use of additives
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
  • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
  • A62D3/37—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by reduction, e.g. hydrogenation
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/04—Pesticides, e.g. insecticides, herbicides, fungicides or nematocides
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/20—Organic substances
  • A62D2101/22—Organic substances containing halogen
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
  • A62D2101/20—Organic substances
  • A62D2101/28—Organic substances containing oxygen, sulfur, selenium or tellurium, i.e. chalcogen
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D2203/00—Aspects of processes for making harmful chemical substances harmless, or less harmful, by effecting chemical change in the substances
  • A62D2203/10—Apparatus specially adapted for treating harmful chemical agents; Details thereof

Definitions

• organohalogen compounds that may generate acids include polychlorinated biphenyls (PCBs), chlorinated napthalenes, chlorinated benzenes and halogenated solvents.
• PCBs polychlorinated biphenyls
• Such degraded oil is generally disposed as low grade fuel oil, valued at less than V* its original cost.
• significant breakdown of the oil during hydrogenation by standard methods can also be caused by the catalyst itself, usually due to acidic sites on the catalyst support. Oils such as hydrocarbon transformer oils represent a large capital investment.
• the process results in a product oil which can be reused for its original use.
• the process would reverse the oxidation reactions by converting the oxidised species back into hydrocarbons, but which is carried out under reaction conditions which do not significantly alter the chemical composition of the oil.
• Objects of the present invention are to provide a process for removal of halide from a halide containing organic compound in a solvent, a process for simultaneous removal of halide from a halide containing organic compound and reduction of an oxygen containing organic compound in a solvent, a process for removal of halide from a halide containing organic compound, a process for reduction of an oxygen containing organic compound in a solvent, a system for removal of halide from a halide containing organic compound in a solvent, a system for simultaneous removal of halide from a halide containing organic compound and the reduction of an oxygen containing organic compound in a solvent, and a system for reducing an oxygen containing organic compound in a solvent.
• a process for removal of halide from a halide containing organic compound in a solvent comprising: exposing a solvent having a halide containing organic compound, in the presence of hydrogen and a hydrogen halide scavenger, to a catalyst which is capable, in the presence of hydrogen, of converting the halide in the halide containing organic compound to hydrohalic acid, at a pressure and at an elevated temperature and for a time sufficient to convert the halide in the halide containing organic compound to hydrohalic acid; and neutralising the hydrohalic acid so formed with the hydrogen halide scavenger.
• Examples of reactions included within (but not restricting) the scope of the process of the first embodiment are as follows:
• R -R are organic moieties which may be the same or independently different from one another. Further all or part of the added amines in equations (lb), (Ic) and (Id) may react with hydrogen to give less substituted amines and/or ammonia:
• Hydrogen halide scavengers are not restricted to ammoniaand amines as many nitrogen- containing substance which will generate ammonia or an amine under the conditions of the process will suffice. For example:
• a process for simultaneous removal of halide from a halide containing organic compound and reduction of an oxygen containing organic compound in a solvent comprising: exposing a solvent having a halide containing organic compound and an oxygen containing organic compound, in the presence of hydrogen and a hydrogen halide scavenger, to a catalyst which is capable, in the presence of hydrogen, of:
• R'-R 8 are organic moieties which may be the same or independently different from one another.
• a process for removal of halide from a halide containing organic compound comprising: dissolving the halide containing organic compound in a solvent; exposing the solvent having a halide containing organic compound, in the presence of hydrogen and a hydrogen halide scavenger, to a catalyst which is capable, in the presence of hydrogen, of converting the halide in the halide containing organic compound to hydrohalic acid, at a pressure and at an elevated temperature and for a time sufficient to convert the halide in the halide containing organic compound to hydrohalic acid; and neutralising the hydrohalic acid so formed with the hydrogen halide scavenger.
• the step of: neutralising any catalyst acid sites with the hydrogen halide scavenger is also part of the process.
• a process for reduction of an oxygen containing organic compound in a solvent comprising: exposing a solvent having an oxygen containing organic compound, in the presence of hydrogen and acid scavenger, to a catalyst which is capable, in the presence of hydrogen, of:
• R 2 -R 7 and R 9 are organic moieties which may be the same or independently different from one another and X is an anion either free or incorporated into the catalyst active sites or both.
• X includes either oxygen or sulphur.
• a system for removal of halide from a halide containing organic compound in a solvent comprising: a reactor having an inlet and outlet and a catalyst which is capable, in the presence of hydrogen, of converting halide in a halide containing organic compound to hydrohalic acid, for exposing a solvent having the halide containing organic compound, in the presence of hydrogen and a hydrogen halide scavenger, to the catalyst, at a pressure and at an elevated temperature and for a time sufficient to convert the halide in the halide containing organic compound to hydrohalic acid; and for neutralising the hydrohalic acid so formed with the hydrogen halide scavenger wherein the neutralising results in a neutralisation product(s), that does not substantially precipitate on the catalyst; means for heating the reactor to an elevated temperature wherein the neutralisation product(s) does not substantially precipitate on the catalyst, the means for heating being operatively associated with the reactor; and means for feeding the hydrogen
• a system for simultaneous removal of halide from a halide containing organic compound and the reduction of an oxygen containing organic compound in a solvent comprising: a reactor having an inlet and outlet and a catalyst which is capable, in the presence of hydrogen, of converting halide in a halide containing organic compound to hydrohalic acid, and reducing an oxygen containing organic compound, for exposing a solvent having the halide containing organic compound and the oxygen containing organic compound, in the presence of hydrogen and a hydrogen halide scavenger, to the catalyst, at a pressure and at an elevated temperature and for a time sufficient to convert the halide in the halide containing organic compound to hydrohalic acid and to reduce the oxygen containing compound, and for neutralising the hydrohalic acid so formed with the hydrogen halide scavenger wherein the neutralising results in a neutralisation product(s), that does not substantially precipitate on the catalyst; means for heating the reactor to an elevated temperature where
• the systems of the fifth and sixth embodiments may further comprise: means for removing the exposed solvent from the reactor the means for removing being operatively associated with the outlet; and means for separating non solvent materials from the exposed solvent, the means for separating being operatively associated with the means for removing.
• a system for reducing an oxygen containing organic compound in a solvent comprising: a reactor having an inlet and outlet and a catalyst which is capable, in the presence of hydrogen, of reducing an oxygen containing organic compound, for exposing a solvent having the oxygen containing organic compound, in the presence of hydrogen and an acid scavenger, to the catalyst, at a pressure and at an elevated temperature and for a time sufficient to reduce the oxygen containing compound, and for any acid in the solvent and any catalyst acid sites with the acid scavenger wherein the neutralising results in a neutralisation product(s), that does not substantially precipitate on the catalyst; means for heating the reactor to an elevated temperature wherein the neutralisation product(s) does not substantially precipitate on the catalyst, the means for heating being operatively associated with the reactor; and means for feeding the hydrogen, the acid scavenger and the solvent into the inlet the means for feeding being operatively associated with the inlet.
• the system of the seventh embodiment may further comprise: means for removing the exposed solvent from the reactor the means for removing being operatively associated with the outlet; and means for separating non solvent materials from the exposed solvent, the means for separating being operatively associated with the means for removing.
• the means for heating the reactor may heat the reactor itself by for example an electrical heater or a steam jacket.
• the solvent may be preheated prior to entering the reactor and the reactor may be insulated against loss of heat.
• the reduction of the oxygen containing organic compound may be decarboxylating a carboxylic acid, reducing a carboxylic acid, reducing an alcohol, reducing a peroxide, reducing a hydroperoxide, reducing an ester, reducing an acid halide, reducing a ketone, decarbonylating an aldehyde, reducing an aldehyde and/or reducing an ether, for example (for other examples of possible reduction of oxygen containing organic compounds see J.
• One aspect of the invention is concerned with mild hydrogenation of an oil (such as a transformer oil) in a packed bed catalytic reactor. Under these conditions hydrogen reacts with heteroatoms in the oil itself, and also with PCBs, HCBs and other chlorinated hydrocarbons present. Oxygen present in compounds resulting from ageing of the oil in service is converted to water. Any PCBs, HCBs and other chlorinated species are converted to hydrogen chloride and light hydrocarbons.
• a basic nitrogen containing compound additive eg trimethylamine, triethylamine and/or NH 3
• the pressure and elevated temperature in the reactor are such that ammonium chloride or the like does not substantially precipitate on the catalyst in the catalytic reactor.
• the downstream process typically involves separation of gases and light hydrocarbons from the regenerated transformer oil, and washing stages for the product oil to remove chlorides formed as a reaction product of PCB, HCB and other chloro-organics destruction.
• the processes of the first to third embodiments result in the reduction of the halogenated hydrocarbons to the corresponding hydrocarbon and the formation of ammonium halide or similar ammonium compound.
• the processes comprise the additional step of separating the reaction product(s) of the hydrogen halide scavenger and hydrogen halide, separating the reaction product(s) of the hydrogen and contaminants such as oxygen containing organics, and any unused gaseous hydrogen and unused hydrogen halide scavenger from the solvent.
• the processes of the first to third embodiments may further comprise: separating reaction products resulting from the exposing of the solvent and the neutralising of the hydrohalic acid, from the solvent.
• unused gaseous hydrogen can be recycled.
• the processes of the first to third embodiments may further comprise: neutralising any catalyst acid sites with the hydrogen halide scavenger.
• the processes of the first to fourth embodiments may further comprise: removing the exposed solvent from the catalyst; and separating non solvent materials from the exposed solvent.
• the processes of the first to third embodiments are generally conducted wherein at the pressure and the elevated temperature: the neutralising of the hydrohalic acid formed with hydrogen halide scavenger results in a neutralisation product(s) that does not substantially precipitate on the catalyst, and the processes further comprise: removing the exposed solvent from the catalyst; and separating non solvent materials from the exposed solvent.
• the processes of the first to third embodiments are generally conducted wherein at the pressure and the elevated temperature: the neutralising of the hydrohalic acid formed with hydrogen halide scavenger results in a neutralisation product(s) comprising a neutralisation product(s) selected from the group consisting of vapourised ammonium halide and dissociated ammonia and gaseous hydrohalic acid, that does not substantially precipitate on the catalyst, and the processes further comprise: removing the exposed solvent from the catalyst; and separating non solvent materials from the exposed solvent.
• the halide is selected from the group consisting of fluoride, chloride, bromide and iodide.
• the halide is chloride.
• the pressure is in the range IMPa -lOMPa and the elevated temperature is in the range 300-375°C
• the solvent comprises transformer oil
• the halide is chloride
• the hydrogen halide scavenger comprises ammonia.
• the processes of the first to third embodiments are particularly useful for the destruction of chlorinated organics generally including dioxin, polychlorinated biphenyl compounds (PCBs - for examples of different types of PCBs and PCB derivatives see U.S Patent no.
• PCBs polychlorinated biphenyl compounds
• hydrocarbon oils wherein a hydrocarbon oil containing a polychlorinated biphenyl compound is fed to a catalytic reactor with gaseous hydrogen and at least one hydrogen chloride scavenger.
• Any catalyst which is capable, in the presence of hydrogen, of converting the halide in the halide containing organic compound to hydrohalic acid, or which is capable of converting the halide in the halide containing organic compound to hydrohalic acid and reducing the oxygen containing organic compound may be used in the process of the invention.
• the catalyst is used in the form of a catalyst bed.
• the catalyst may be a typical hydrotreating catalyst having an active metal chosen from molybdenum, tungsten, chromium, iron, cobalt, nickel, Raney nickel, platinum, palladium, iridium, osmium, ruthenium, copper, manganese, silver, rhenium, rhodium, technetium, vanadium, nickel/molybdenum, nickel/tungsten, nickel/chromium, nickel/iron, nickel/cobalt, nickel/platinum, nickel/palladium, nickel/iridium, nickel/copper, nickel/manganese, nickel/silver, nickel/rhenium, nickel/osmium, nickel/rhodium, nickel/ruthenium, nickel/technetium, nickel/vanadium, Raney nickel/molybdenum, Raney nickel/tungsten, Raney nickel/chromium, Raney nickel/iron, Raney nickel/cobalt, Raney nickel/platinum, Raney nickel/palladium, Raney
• Catalyst activation is typically carried out under a pressure of 0.1 - 50MPa, more typically 1 - 20MPa, even more typically 3 - lOMPa, and yet even more typically about 5MPa, typically at a temperature in the range 100°C - 500°C, more typically 200°C - 400°C, and yet even more typically 225°C - 375°C by subjecting the catalyst to either H 2 S in hydrogen (typically lvol%-30vol%, more typically 3vol%-10vol of H 2 S in hydrogen) or a hydrocarbon solvent (eg see list of hydrocarbon solvents in this specification) having a sulphided hydrocarbon dissolved therein such as di(C C 6 alkyl)disulphide, di(C 2 -C 6 alkylene)disulphide or di(C 2 -C 6 alkyne)disulphide (eg dimethyldisulphide) or indeed any substance which can be converted into hydrogen sulphide by reaction with hydrogen.
• a typical process for sulphiding the catalyst is as follows: (a) After pressurising the system and establishing the hydrogen flow, feed was introduced at a rate of 25 - 250 ghr "1 . The temperature is then incremented in stages of 10-50°C, typically 25°C, every 15-120minutes, typically every 30 minutes to 200°C - 275°C, typically 250°C, and held at this point until hydrogen sulfide can be detected in the off-gas (eg by using Drager tubes). After detection of the hydrogen sulfide, the temperature is increased in stages of 10-50°C, typically 25°C, (ensuring a breakthrough of H 2 S each time) to 320-400°C, typically 350°C.
• the temperature is held at 320-400°C, typically 350°C, for 1-4 hours, typically 2 hours, and then decreased to 100-250°C, typically 200°C, at which point the feed and heaters are turned off and the catalyst allowed to cool slowly under a steady hydrogen flow or under an atmosphere of hydrogen (eg for 5-36 hours, typically 12 hours under 0.1 - 50MPa, more typically 1 - 20MPa, even more typically 3 - lOMPa, and yet even more typically about l-5MPa and further even more typically 3.5MPa).
• a steady hydrogen flow or under an atmosphere of hydrogen eg for 5-36 hours, typically 12 hours under 0.1 - 50MPa, more typically 1 - 20MPa, even more typically 3 - lOMPa, and yet even more typically about l-5MPa and further even more typically 3.5MPa).
• catalysts typically when two catalysts are used, they are used in molar ratios in the range 1:99 to 99: 1, more typically, 10:90 to 90: 10, even more typically 25:75 to 75:25 and yet more typically 50:50.
• three catalysts they are used in molar ratios in the range 1: 1:98 to 1:98: 1 to 98: 1: 1 , more typically, 10: 10:80 to 10:80: 10 to 80: 10: 10, even more typically 33.3:33.3:33.3.
• Typically when four catalysts are used they are used in molar ratios in the range 1:1: 1:97 to 1: 1:97: 1 to 1:97:1: 1 to 97: 1:1:1, more typically, 25:25:25:25.
• Particularly preferred commercially available catalysts are sulfided Ni/Mo (1- 6 Ni/2-15%Mo, typically 2%Ni/7%Mo) supported on ⁇ alumina, platinum supported on ⁇ alumina, and palladium on ⁇ alumina (the latter two catalysts may be simply reduced in hydrogen at elevated temperatures (200-800°C) prior to use).
• the processes of the first to third embodiments may further comprise: monitoring the hydrogen halide scavenger content in the solvent after exposing the solvent to the catalyst and adjusting the amount of hydrogen halide scavenger in the solvent exposed to the catalyst and/or the temperature during the exposure and/or the pressure during the exposure whereby there is a detectable amount of hydrogen halide scavenger in the solvent after exposing the solvent to the catalyst such that the amount of hydrogen halide scavenger in the solvent at the time of exposing of the solvent to the catalyst is an amount effective to completely neutralise hydrogen halide and any other acids in the solvent and any acids formed during the exposure of the solvent to the catalyst including neutralising any catalyst acid sites.
• the processes of the first to third embodiments may further comprise: monitoring the halide content in the solvent prior to exposing the solvent to the catalyst and , adjusting the amount of hydrogen halide scavenger and/or hydrogen exposed to the catalyst and/or the temperature during the exposure and/or the pressure during the exposure whereby there is a detectable amount of hydrogen halide scavenger in the solvent after exposing the solvent to the catalyst such that the amount of hydrogen halide scavenger in the solvent at the time of exposing of the solvent to the catalyst is an amount effective to completely neutralise hydrogen halide and any other acids in the solvent and any acids formed during the exposure of the solvent to the catalyst including neutralising any catalyst acid sites.
• the process of the fourth embodiment may further comprise: monitoring the acid scavenger content in the solvent after exposing the solvent to the catalyst and adjusting the amount of acid scavenger in the solvent exposed to the catalyst and/or the temperature during the exposure and/or the pressure during the exposure whereby there is a detectable amount of acid scavenger in the solvent after exposing the solvent to the catalyst such that the amount of acid scavenger in the solvent at the time of exposing of the solvent to the catalyst is an amount effective to completely neutralise any acids in the solvent and any acids formed during the exposure of the solvent to the catalyst including neutralising any catalyst acid sites.
• the oxygen containing organic compound is typically a compound resulting from ageing /oxidation of the solvent (eg transformer oil).
• the hydrogen halide scavenger or the acid scavenger is a basic nitrogen containing compound which is chosen such that the step of neutralising the hydrohalic acid with the basic nitrogen containing compound results in a gaseous or volatile compound under the conditions in the catalytic reactor (which in the case of the first to third embodiments is a function of pressure, temperature and halide content in the reactor and in the case of the fourth embodiment is a function of pressure, temperature and anion content in the reactor) such that the compound does not precipitate in the catalytic reactor and can be readily removed from the catalyst and the catalytic reactor.
• any suitable nitrogen compound which is a base or is transformed into a base and which will neutralise hydrogen halide under the reaction conditions of the process of the invention and which under the reaction conditions of the exposure to the catalyst, can be readily removed from the catalyst, may be used in the process of the invention.
• the hydrogen halide scavenger comprises a nitrogen containing compound which is a base or which is transformed into a base (such as ammonia) in the reactor.
• the gaseous hydrogen being added to the catalytic reactor may itself independently contain a basic compound such as ammonia. It is particularly desirable to use ammonia gas and/or a nitrogen containing organic basic compound whereby under process conditions, ammonium halide is formed in such a way that it does not substantially precipitate on the catalyst (i.e.
• suitable basic nitrogen containing compounds include tri(C---C 7 alkyl)amines including trimethylamine, triethylamine, tripropylamine, or tributylamine etc., di(C 1 -C 7 alkyl)amines including dimethylamine, diethylamine, dipropylamine, dibutylamine, diisobutylamine, or diisopropylamine, etc., C r C 7 alkylamines including methylamine, ethylamine, propylamine, butylamine, isopropyl-amine, isobutylamine, etc., C 2 -C 9 primary, secondary and tertiary alkylideneamines, C 3 -C 9 cycloalkylamines including cyclohexylamine, cyclopentylamino and cycloheptylamino, C 6 -C 12 arylamin
• heterocycles examples include pyrryl, pyrimidinyl, quinolinyl, isoquinolinyl, indolyl, piperidinyl, pyridinyl, imidazolyl, imidazolidinyl, morpholinyl, pyrrolidinyl, pyrazolyl, pyrazolinyl, tetrazolyl, triazolyl, benzimidazolyl, pyrrolinyl, quinuclidinyl, azanorbornyl, isoquinuclidinyl and the like. e.g.
• tertiary amines such as trialkyl amines (trimethylamine, triethylamine, pyridines and pyridine bases (4- dimethylaminopyridine, 4-pyrrolidylaminopyridine etc.).
• the lower alkylamino includes alkylamino having straight or branched chain alkyl moiety having 1-6 carbon atoms,
• the di- and tri-lower alkylaminos include amino substituted by the same or different and straight or branched chain alkyl moiety having 1-6 carbon atoms.
• amine organic bases include n-amylamine, n-hexylamine, n-octylamine, n-decylamine, laurylamine, palmitylamine, dibutylamine, tributylamine, N,N-dimethyl-benzylamine, N,N-dimethyl-p- toluidine, phenethyldibutyl-amine, N,N,N',N'-tetramethylhexamethylenediamine,
• alkyl includes within its meaning straight and branched chain alkyl groups. Examples of such groups are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, sec-amyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl, 4-methylpentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1, 1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,2,2-tri- methylpropyl, 1, 1,2-trimethylpropyl, and the like.
• cycloalkyl refers to mono- or polycyclic alkyl groups, or alkyl substituted cyclic alkyl groups. Examples of such groups include cyclopropyl, methylcyclopropyl, cyclobutyl, methylcyclobutyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, cyclohexyl, methyl cyclohexyl, ethylcyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl and the like.
• alkylidene includes reference to unsaturated divalent alkyls.
• the term also refers to such radicals in which one or more of the bonds of the radical from part of a cyclic system and at least one of the cyclic atoms is nitrogen. Examples of such radicals are groups of the structure
• aryl refers to single, polynuclear and fused residues of aromatic hydrocarbons or aromatic heterocyclic ring systems. Examples of such groups are phenyl, biphenyl, naphthyl, pyridyl, thienyl, furyl, pyrryl, indolyl, pyridazinyl, pyrazolyl, pyrazinyl, thiazolyl, pyrimidinyl, quinolinyl and isoquinolinyl.
• aralkyl refers to alkyl groups substituted with one or more aryl groups as previously defined. Examples of such groups are benzyl, 2-phenylethyl and 1- phenylethyl.
• the concentration and amount of hydrogen halide scavenger compound added to the reactor will depend upon the concentration of halide containing organic compound(s) such as PCBs in the solvent (such as hydrocarbon oil) and the actual hydrogen halide scavenger compound being used.
• the amount and concentration of hydrogen halide scavenger compound present is generally sufficient to react with all the hydrogen halide formed as a result of the reduction of the halide containing organic compound(s) present in the solvent (i.e. of hydrogen halide scavenger compound present is generally at least stoichiometric or greater than stoichiometric of the amount of HC1 formed).
• hydrogen halide scavenger is generally 1M:1M or 1M:>1M (typically between 1M and 100M, more typically between 1M and 10M and more typically between 1M and 3M).
• the hydrogen halide scavenger compound may be added to the solvent such as, for example, contaminated transformer oil, prior its being added to a catalytic reactor or it may be added directly to the reactor or it may be added to the gaseous hydrogen entering the reactor. Alternatively the hydrogen halide scavenger may be added to the gaseous hydrogen prior to it being introduced to the catalytic reactor.
• the reaction takes place under elevated temperature and pressure in a catalytic reactor.
• the operating temperature and pressure are adjusted to take into account the halide content of the feed solvent (which can be monitored, batchwise or continuously) so that deposition of NH C1 formed as a consequence of the hydrogen halide scavenger reacting with HC1 in the reactor is minimised or substantially prevented in the reactor.
• substantially hydrocarbon is used herein to mean that the compounds contain no ' non-hydrocarbon substituents or non- carbon atoms that significantly affect the hydrocarbon characteristics or properties of such compounds relevant to their use herein as solvents.
• the aromatic compounds can be mononuclear or polynuclear.
• the aliphatic substituents on the aromatic compounds can be straight chain hydrocarbon groups of 1 to about 7 carbons, cyclic groups of about 3 to about 9 carbons, or mixtures thereof.
• the aromatic compounds can be mono-substituted or poly- substituted.
• the poly-substituted aromatic compounds are preferably di-substituted.
• the cycloaliphatic compounds can have from about 3 to about 9 ring carbon atoms, preferably 5 or 6 ring carbon atoms, and can be saturated or unsaturated. Examples include cyclopropane, cyclobutane, cyclopentane, cyclopentene, 1,3-cyclopentadiene, cyclohexane, cyclohexene, 1,3- cyclo-hexadiene, etc.
• the aliphatic substituents on the aliphatic-substituted cycloaliphatic compounds can be Straight chain hydrocarbon groups of 1 to about 7 carbon atoms, preferably 1 to about 3 carbon atoms.
• the rings of the cycloaliphatic compounds can be mono-substituted or poly-substituted.
• the poly-substituted compounds are preferably di-substituted. Examples include methylcyclopentane, methylcyclohexane, 1,3 -dimethyl cyclohexane, 3 -ethyl cyclopentene, 3,5-dimethylcyclopentene, etc.
• the solvent is a liquid hydrocarbon solvent.
• Suitable liquid hydrocarbons include diesel oil, straight run distillates, kerosene, transformer oil, motor oil, aromatics such as benzene, tetralin, pseudocumene, o-xylene, m-xylene, p-xylene, ethylbenzene, isopropylbenzene, mesitylene, naphthalene, anthracene, styrene, 1- methylnaphthalene, 1,2-dimethylnaphthalene, 1,6-dimethylnaphthalene, 1,2,3,4- tetrahydronaphthalene, butylbenzene, sec-butylbenzene, isobutylbenzene, tert-butylbenzene, cyclohexylbenzene, p-cymene, cumene, 4-tert-butyltoluene, and toluene, or aliphatics such as cyclohexane,
• the solvent may be an oil such as a mineral oil eg paraffin oil, (including an oil used in transformers), a vegetable oil eg arachis oil, olive oil, sesame oil, groundnut oil, peanut oil or coconut oil, a fish oil eg tuna oil, mackeral oil, sand eel oil, menhaden oil, anchovy oil, sardine oil, horse mackeral oil, salmon oil, herring oil, cod oil, capelin oil, pilchard oil, sprat oil, whale oil, Pacific oyster oil, Norway pout oil, seal oil and sperm whale oil or a plant oil eg pine oil, wheat germ oil and linseed oil).
• a mineral oil eg paraffin oil
• a vegetable oil eg arachis oil, olive oil, sesame oil, groundnut oil, peanut oil or coconut oil
• a fish oil eg tuna oil, mackeral oil, sand eel oil, menhaden oil, anchovy
• solvents that may dissolve halogenated organic compounds may be found in "Chemical Safety Data Sheets", Volume 1: Solvents, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge, United Kingdom and Techniques of Chemistry, Volume II, "Organic Solvents", J.A. Riddick, W.B. Bunger and T.K. Sakano, 4th edition, A. Weissberger editor, J. Wiley & Sons, New York, 1986, the contents of both of which are incorporated herein by cross reference. Ideally enough solvent is mixed with the halogenated organic compound such that all of the halogenated hydrocarbon is dissolved. The amount of solvent will accordingly depend upon the ability of said solvent to dissolve the halogenated organic compound.
• the concentration of halogenated organic compound in the solution formed in step one is up to 35wt% , typically up to 10wt%, more typically 0.1-5wt% .
• the concentration of halogenated organic compound is typically O. lppm to 10,000ppm, more typically lppm-lOOOppm.
• the amount of gaseous hydrogen added to the reactor will depend on the level of halogenated organic compound(s) to be destroyed and other contaminants present in the oil and may be varied by altering the pressure in the reactor during the exposure (in particular this can be generally achieved by adjusting the input the hydrogen pressure and ammonia pressure) or the hydrogen to oil ratio or both.
• the pressure (and elevated temperature) are generally chosen such that the reaction product of the hydrogen halide scavenger and hydrogen halide (or in the case of the fourth embodiment the reaction product of the acid scavenger and acid catalyst sites or other acids) does not substantially precipitate onto the catalyst during the exposure.
• the pressure at which hydrogen is delivered to the catalytic reactor is such that the pressure in the reactor during the exposure is in the range of 0.01 - 50MPa, more typically 1-20 MPa, even more typically 2-10MPa, yet even more preferably 3-7 MPa.
• a more typical pressure during the exposure in the catalytic reactor is in the range 3-5 MPa.
• the pressure in the catalytic reactor during the exposure is generally monitored with a pressure gauge.
• the elevated temperature will typically depend upon the catalyst being used and the level of halogenated organic compound(s) present in the contaminated oil.
• the elevated temperature (and pressure) are generally chosen such that the reaction product of the hydrogen halide scavenger and hydrogen halide (or in the case of the fourth embodiment the reaction product of the acid scavenger and acid catalyst sites or other acids) does not substantially precipitate onto the catalyst during the exposure.
• the elevated temperature is in the temperature range 200-550°C more typically, 200-500°C. More typically the temperature of the reaction is in the range 250-350°C.
• the process of the invention in conducted at a temperature which maximises the destruction of the halogenated hydrocarbons while minimising thermal destruction of the solvent.
• the catalytic reactor is maintained at a temperature of more typically 275-375°C and even more typically 300-350°C.
• the efficiency of reduction of halogenated organic compound(s) and/or oxidised organics present in the solvent is dependent upon a number of factors.
• One of the important factors is the residency of the solvent to be purified in relation to catalyst.
• the residency time is sufficiently long so that substantial conversion of all the required halogenated organic compound(s) and/or oxidised organics present in the solvent to be occurs so that they are substantially reduced.
• the optimum residency time of the gas is dependent on a number of factors including the type of solvent to be purified, the catalyst selected, the temperature selected and the impurities to be removed.
• the hourly space velocity i e.
• grams of solvent fed to the reactor per gram or catalyst per hour) of solvent fed to the catalytic reactor will depend upon the level of halogenated organic compound(s) and/or oxidised organics present in the solvent and the type of reactor being used and the level of other variants.
• a preferred hourly space velocity is in the range of 0.1 to 10 grams of solvent per gram of catalyst per hour.
• Hourly space velocities typically between 1 and 3600, more typically 3 and 2400 litre feed solvent per kg of catalyst per hour (1/kg/hr), typically 1 to 1800 1/kg/hr, more typically 20 to 500 1/kg/hr and even more typically 50 to 275 1/kg/hr.
• the contact time of the solvent with the catalyst is between 1 sec and 5 minutes, more typically 0.15 seconds and 20 seconds and even more typically between 0.25 and 5 seconds.
• the solvent is preheated prior to contact with the catalyst.
• a number of features may be altered. These include the path length of the gas over the catalyst, pressure, temperature of the reactor, the flow rate of the gas and the volume of the reactor.
• the catalyst may be in the form of powder, granules, discs, pellets, monoliths or other suitable form.
• the catalyst may be in the form of pure catalyst or alternatively it may be held together with a binder and/or may be coated or deposited on a support or carrier by techniques well known in the art (e.g. by vacuum deposition, impregnation, electrodeposition).
• Suitable binders or support materials include but are not limited to alumina including ⁇ -alumina, mullite, cordierite, mullite aluminium titanate, magnesia, zirconia, zirconia spinels, titania, siliea-alumina including amorphous silica-alumina, and clays and mixtures thereof.
• the amount of binder may be 3 - 50wt% of the catalyst, more typically 5 to 30wt% base on the total weight of the catalyst.
• the catalyst has a surface area to volume ratio of at least 0.5 ⁇ _ /gm, more typically between 25 and 500m ⁇ /g, and even more typically between 50 and 250m2/g.
• the reactor may be a single pass reactor packed with the catalyst, such as for example a paniculate catalyst disposed in a fixed bed within the reactor or a catalyst deposited on or impregnated in a ceramic foam carrier (e.g. ceramic foams made from the aforementioned refractory oxides particularly alumina and ⁇ -alumina) disposed within the reactor, or a multiple pass reactor packed with the catalyst.
• the catalyst may be arranged fixedly within the reactor so as to provide a high tortuosity for the feed gas (typically between 1.0 and 10.0, more typically 1.3 to 4.0; "tortuosity" with reference to a fixed catalyst bed is the ratio of the pathlength of gas flowing through the bed to the length of the shortest straight line through the bed).
• the catalyst may be in the form of a fluidised bed.
• the reactor may be operated so that the feed gas contacts the catalyst under isothermal conditions or adiabatic conditions ("adiabatic" referring to reaction conditions wherein substantially all heat loss and radiation from the catalyst bed is prevented except for the heat leaving in the exit gas from the reactor).
• adiabatic referring to reaction conditions wherein substantially all heat loss and radiation from the catalyst bed is prevented except for the heat leaving in the exit gas from the reactor).
• the process of the second embodiment is typically able to provide a processed transformer oil having (a) A dielectric dissipation factor of 5 - 6x10 " (max); (b) A resistivity >200 Gohmm; (c) A dielectric strength >60kV; (d) An acidity of 0.01 to 0.03 mg KOH/g (max); (e) Interfacial tension of >30 mN/M; and (f) PCB content ⁇ 0.1 mg/kg.
• FIG. 1 depicts schematically a system for the simultaneous removal of chlorine from a chlorine containing organic compound and the reduction of oxygen containing organic compounds in spent transformer feed oil;
• Fig. 2 depicts the temperature at which ammonium chloride deposits as a function of chlorine content in a feed oil at a of pressure 3.5MPa;
• Fig. 3 depicts schematically a process flowsheet for the removal of chlorinated hydrocarbons;
• Fig. 4 is a graph of hydrogen consumption vs product chlorine content - Run 2;
• Fig. 5 is a graph of hydrogen consumption vs dielectric dissipation factor - run 2;
• Fig. 6 is a graph of hydrogen consumption vs reciprocal resistivity - run 2;
• Fig. 7 is a graph of product sulfur content vs time on stream - run 4;
• Fig. 8 is a graph of product nitrogen content vs time on stream - run 4;
• Fig. 9 is a graph of product chlorine content vs time on stream - run 4;
• Fig. 10 is a graph of dielectric dissipation factor vs time on stream - run 4;
• Fig. 11 is a graph of dielectric strength vs time on stream - run 4;
• Fig. 12 is a graph of interfacial tension vs time on stream - run 4;
• Fig. 13 is a graph of resistivity vs time on stream - run 4;
• Fig. 14 depicts schematically a pilot plant system used in various experiments; and
• Fig. 15 depicts schematically a catalytic reactor used in various experiments.
• the process described may be configured as a mobile transformer oil treatment unit capable of processing 10,000 litres per day in continuous operation. It is anticipated that such a unit will be suitable for on-site retreatment of oils in transformers containing 10,000 litres of oil or greater.
• the maximum oil volumes in transformers on the New South Wales supply system are around 110,000 litres with around 94% of network and 42% of distribution transformer oil volume in units greater than 10,000 litres. It is envisaged that in treating transformer oils on-site the particular transformer will be taken off-line and its oil transferred to a transportable storage tank of suitable volume that is also brought on- site.
• Oil will be processed from this tank through the hydrogenation unit and regenerated oil transferred to a transportable product oil tank. Regenerated oil will then be returned to the transformer via a vacuum de-gassing unit.
• the treatment plant described here does not include the de-gassing unit, mobile units for this purpose being already in existence within the power authorities.
• FIG. 1 depicts a system 100 for the simultaneous removal of chlorine from a chlorine containing organic compound and the reduction of oxygen containing organic compounds in spent transformer feed oil 101.
• Spent feed oil 101 from an on-site storage tank (not shown) is introduced to process 100 via a positive displacement charge pump (not shown) where the oil pressure is raised to around 4.3 MPa.
• Feed oil 101 passes via line 102 through high pressure vent condenser 103.
• Feed oil 101 passes in turn via line 104 to product oil heat exchanger 105 where it is heated to 285°C.
• Feed oil 101 then passes via line 106 to final feed heater 107, where it is raised to a temperature of 355° C.
• Heater 107 is an electrical element immersion heater designed to limit maximum oil contact temperatures to around 380 °C.
• Feed oil 101 then passes into reactor 109 via line 108.
• Recycle hydrogen 110 and fresh hydrogen 111 are introduced into reactor 109 via lines 112 and 113, and 114 and 113 respectively.
• Ammonia 115 is also introduced into reactor 109 via lines 116 and 113.
• the chlorine (and/or oxygen content) of feed oil 101 may be monitored by monitor 164 via line 163 which in turn may make appropriate adjustments to the amount of input hydrogen chloride scavenger and input hydrogen via lines 165 and 166 (the amount of chlorine exiting the reactor as ammonium chloride may also be independently or simultaneously monitored by monitor 164 via an appropriate line (not shown) which in turn may make appropriate adjustments to the amount of input hydrogen chloride scavenger and input hydrogen via lines 165 and 166).
• the combination reacts in reactor 109 at approximately 330°C and 3.5 MPa.
• the reactor comprises a single packed bed of a conventional hydrotreating catalyst (which has been sulphided) operating as a trickle bed. At the reaction conditions approximately 7% of the transformer oil enters the vapour phase and around 2.5% of the hydrogen is dissolved in the oil.
• Effluent leaving reactor 109 passes first to heat exchanger 105 via line 117 where it is cooled to 235°C against incoming feed oil. This temperature is marginally above that estimated for the onset of NH 4 C1 deposition and permits maximum cooling of the oil prior to contact with wash water. Under these conditions partial deposition of solid NH C1 may occur and some fraction of this material could then remain in exchanger 105 as a fouling deposit. As the total quantity of NH 4 C1 available for deposition is small, approximately 2.75 kg or 1.8 litres over the course of processing the maximum 110,000 L transformer volume, and only a small fraction of this may deposit in exchanger 105, appropriate configuration of exchanger 105 to account for this possibility wil permit runs of this volume to be satisfactorily completed.
• Cooled reactor effluent from heat exchanger 105 then passes to in-line static mixer 118 via lines 119 and 120 where it is then contacted directly with wash water from the final product oil wash stage via lines 121, 122 and 120.
• the mixed stream is then passed from in-line static mixer 118 to high pressure separator 124 via line 123. Oil, water and gas phases are split in separator 124 which operates at 174°C and 3.3 MPa.
• wash water is introduced to ensure that a liquid phase is present to dissolve NH 4 C1 as it is precipitated while minimising the quantity of aqueous effluent to be discharged from the plant.
• Wash water is used in the system at a rate of 27 kg/h representing a wash water to feed oil 101 rate of 7.46 x 10-2 kg/kg feed oil.
• separator 124 in the vapour stream with H 2 S, trace HC1, light hydrocarbons and some transformer oil vapours.
• the separator waste water phase containing NH 4 C1, NH 3 and H 2 S is sent to a neutraliser drum (not shown) via line 126 for treatment.
• Oil from the high pressure separator 124 passes to heat exchanger 137, via line 136, where it is cooled to 122°C (which can be arranged (not shown) so that it is against incoming feed oil 101).
• Product oil leaving condenser 137 passes to a let-down valve 139 via line 138 where the pressure is reduced to 221 kPa ahead of low pressure separator 141 to which it passes via line 140.
• Overhead vapours from this flash stage contain the majority of water and dissolved non-condensable hydrocarbons in the oil reducing the non-conden sables load on the final de ⁇ gassing plant.
• vapours additionally contain NH 3 and H 2 S and pass to low pressure caustic scrubber 133 via line 142 prior to venting to catalytic oxidation unit (not shown) via lines 134 and 135.
• a very small liquid water flow is separated in the flash drum comprising low pressure separator 141 and the main product oil flow passes to air cooled product cooler 144 via line 143 where its temperature is reduced to 50°C.
• Fresh demineralised water 146 is introduced via line 145 into the product oil stream in line 147 and the combined flow passes via line 148 through in-line mixer 149 and line 150 to wash water Separator 151. Washed product oil 153 is then removed from separator 151 to an oil storage tank (not shown) via line 152 ahead of de-gassing.
• Separated water is passed back to the primary wash stage in high pressure separator 124 via lines 121, 122 and 120, static mixer 118 and line 123.
• a small vapour flow from the wash water separator 151 is passed to the low pressure caustic scrubber 133 (via a line not shown).
• Vapour from the high pressure separator 124 passes to the high pressure vent condenser 103 via line 127 where it is cooled to 50° C against incoming feed oil 101.
• Condensate which is mainly water and small quantities of condensable hydrocarbons, is passed to waste oil separator 131 via line 128, valve 129 and line 130.
• Separated waste oil 154 is collected via line 155 in a drum for separate off- site disposal. Vent gases from separator 131 are passed to the low pressure caustic scrubber 133 via line 132.
• Separated water is passed to a waste water neutraliser (not shown) via line 156.
• Non-condensable gases from the high pressure vent condenser 103 comprise mainly hydrogen, light hydrocarbons, H 2 S and NH 3 . These are passed to the high pressure caustic scrubber 158 via line 157 where H 2 S is removed and collected into the caustic solution. Gases pass counter-current to caustic solution in a packed tower. H 2 S is removed with the recirculated solution becoming saturated in NH 3 . A sufficient quantity of caustic is provided to contain the H 2 S generated in a 110,000 litre transformer run with spent caustic disposed of to appropriate waste processing facilities off-site. Scrubbed gas from scrubber 158 is recycled via lines 159, 112 and 113 to reactor at around 3.27 MPa.
• Non-condensable gases produced in reactor 109 are removed from the system by taking a purge gas flow prior to compression. Purge gases are passed via lines 159, 160, valve 161, lines 162 and 135 to a catalytic oxidation unit (not shown) for combustion and combustion gases released to the atmosphere . Recycle gases comprising H 2 , light hydrocarbons, NH 3 and water are recompressed to 4.1 MPa and pass back to reactor 109.
• Water streams from the HP and LP Separators 158 and 133 and waste oil separator 131 contain dissolved H 2 S, NH 4 C1, trace HC1 and trace H 2 . These pass to waste water neutraliser (not shown) after neutralisation with HCI solution. Neutralised water is stripped with a flow of scrubbed purge gas in a packed tower on the inlet to the waste water neutralise. Separated water from this drum is passed to drain with its dissolved NH 4 C1. Any hydrocarbon liquids captured accumulate in the drum and are removed periodically. Stripper gas is passed back to the vent gas flow leaving the low pressure caustic scrubber 133.
• Purge gas from the high pressure gas recirculation loop and all scrubbed vent gases pass together to the catalytic oxidation unit (not shown) where they are burnt at approximately 600° C with approximately 400% excess air.
• Incoming air is provided with electrical pre ⁇ heating for start-up and for trimming catalyst bed temperature control if required.
• Optimum operating conditions for catalytic reactor 109 in terms of H 2 and hydrogen chloride scavenger (eg NH 3 ) to feed ratios, reactor temperature and pressure may be adjusted to suit the particular solvent composition (eg transformer oil composition) being treated, particularly, in relation to its chlorine content. Deposition of NH C1 in the reactor effluent heat exchanger 105 is possible.
• reactor conditions i.e.
• deposition temperature is primarily dependent on the chlorine content of the feed (which may vary considerably between individual solvents such as transformer oils). For example, a chlorine content of 19.1 ppmw is about equivalent to 32 ppmw PCB as hexachlorobiphenyl and the estimated deposition temperature is around 235°C. It is important that for a given chlorine (or other halide) content in the feed solvent, values of temperature and pressure are chosen such that there is no deposition of ammonium chloride (or other ammonium halide) or other acid neutralisation product, on the catalyst.
• Such deposition would firstly reduce catalyst activity by blocking active sites and eventually cause physical blockage of the reactor itself.
• the outlet of reactor effluent exchanger 105 is maintained at around this temperature to avoid deposition in the absence of liquid water. Wash water is introduced downstream of exchanger 105 at a sufficient rate to ensure the existence of sufficient liquid water to wash the oil and dissolve the NH 4 C1.
• As feed chlorine content increases the temperature at which NH 4 C1 deposition decreases requiring an increase in the exchanger 105 outlet temperature which in turn results in an increased wash water requirement and increased load on the high pressure vent condenser 103.
• Estimated sensitivity of deposition temperature to feed of deposition temperature to feed chlorine content is shown in Figure 2.
• Removal of NH 4 C1 deposits can most likely be normally carried out without disassembly at the completion of a run by allowing a reduced rate of oil at reduced H 2 pressure to flow through the exchanger 105 at near reactor temperature. NH C1 could then be volatilised and subsequently removed in the wash water in the normal way. Processing objectives for the mobile treatment plant are focused on the following main areas:
• Characteristics for the feed oil used in experimental runs defining the design performance data are those of sample HT14-Feed and are as follows: Physical Properties and Composition 1. Boiling range as D-86 simulation based on GC analysis is given in Table BM1.1. TABLE BM1.1 FEED OIL DISTILLATION RANGE
• optimised processing conditions were selected from a broad series of runs, and tested in the experimental rig. This optimised data as represented by sample HT16.3 has been taken as the design basis for the process and is presented below.
• Product oil boiling range is given as the bottom oil before vacuum degassing.
• the boiling range as a D-86 simulation from GC analysis data is given in Table BM1.2.
• Chlorine content 0.06 mg/kg
• Table BM1.3 shows the key insulating oil parameters appearing in specifications as measured for the feed and product oils along with indicative target values. Product oil electrical properties were measured after vacuum degassing at 0.7 mbar and 77°C. TABLE BM1.3 INSULATING OIL PROPERTIES
• Results indicated for product oil based on the optimised experimental run HT-16.3 indicates that with respect to these key parameters the product oil meets the specifications set for new transformer oils.
• Some 26 runs were conducted in this series over a range of operating conditions. Twenty three runs met the target new oil specification with the other three failing by reduced flash point only. In these three runs reactor operating conditions included the highest temperature in conjunction with the lowest space velocities used in the trials, i.e. the most severe hydrogenation conditions in the series. Under these conditions the greater proportion of light ends produced results in an increase in volatile components remaining after vacuum distillation.
• the range of operating conditions covered in the trials is as follows:
• Used hydrocarbon transformer oil containing mixed PCBs equivalent to 20 ppm of Arochlor 1242 (8.3 ppm chlorine) was mixed with 720 ppm of triethylamine, and fed into a high pressure reactor.
• the reactor was a stainless steel tube 15.8 mm ID x 510 mm length, containing 90 g or catalyst (Cyanamid Trilobe HDN 60, 1.6 mm extrudates) in its sulfided form. Hydrogen was co-fed into the reactor at a flow rate of 0.22 litre/gram oil.
• the reactor was incorporated into a high pressure system designed for extended operation.
• PCBs polychlorinated biphenyls
• EXAMPLE 2 Solutions of hexachlorobenzene, DDT, and 1,2,3, 4-tetrachlorodibenzodioxin (an isomer of the environmental pollutant "dioxin") in automotive diesel oil were made, the concentrations being as shown in Table 3. These solutions were mixed with 3600 ppm of triethylamine, (i.e. 500 ppm N) and fed into a high pressure reactor at a rate of 135 gh "1 . The reactor was a stainless steel tube 15.8 mm ID x 510 mm length, containing 90g of catalyst (Cyanamid Trilobe HDN 60 1.6mm extrudates) in its sulfided form held at 350°C. Hydrogen was co-fed into the reactor at a flow rate of 0.22 litre/gram oil and a pressure of 5 MPa. The reactor was incorporated into a high pressure system specially designed for extended operation.
• PCB analyses were carried out by gas chromatography with electron capture detection (ECD); all products contained less than the detection limit of 0.1 mg/kg. It is relevant that samples with 0.05 and 0.27 mg/kg chlorine, (samples from Runs 2 and 6 of Example 1), were both found to contain less than 0.01 mg/kg of PCB, using the more sensitive technique of isotope dilution gc-ms.
• Nitrogen recoveries (Table 3.7) are considerably better than the sulfur figures. This is due to the excellent solubility of ammonia in water, which also accounts for the majority of the nitrogen being found in the aqueous phase. It should be noted that in this run, most of the liberated nitrogen is in the form of ammonia and ammonium sulfide; theoretically, only about 2.8 mg of ammonium chloride is formed per 100 g of feed.
• Mass balances for this run (shown in Table 3.13) are very similar to those of Run 1, averaging 99.73%.
• Vacuum treatment was carried out on combined bulk and mass balance subsamples (where available), to an end point of 87°C. From the results of the redistillation of sample HT15- 12, reported in Section 3.2.5, this temperature was expected to give flash points around 142°C, ie just above the specified minimum for transformer oils. This gave overall yields averaging more than 99.5 % , as shown in Table 3.19.
• the flash point figures are very close to what was expected, and show that the vacuum treatment parameters can be tailored to fit a desired flash point value.
• Average measured weight loss during oil washing was 0.025 g/100 g, a quantity attributable to both evaporation of highly volatile products and mechanical losses. Together, these three sources of evaporative and mechanical loss account for 0.111 g.
• the amount of water recovered from washing the oils was always greater than the total quantity put in. After allowing for the contained ammonia, hydrogen sulfide and hydrogen chloride, this excess averaged 0.079 g/100 g. This quantity, which is not included in the mass balance tables, completes the tally of "missing" material. Part of this extra water is likely to be moisture in the feed oil, but the majority would originate from hydrogenation of oxidised oil species.
• Vacuum treatment was carried out on combined samples HT18-1A, IB and IC, and on HT18-1A plus IB to an end point of 87°C. Despite the fact that 0.04 to 0.10% more is lost through PCB removal, the residue yields shown in Table 3.35 are significantly higher than those of Runs 3 and 4. This is attributable to less cracking at the higher space velocity of this run, and indicates that the much greater hydrogen chloride concentration has had no significant effect, being completely neutralised by the excess of hydrogen chloride scavenger.
• Nitrogen, sulfur and chlorine recoveries are shown in Tables 3.38 to 3.40. More than half of the chlorine fed into the reactor was not recovered in this run, the loss totalling just over 400 mg. It should be noted that the estimated ammonium chloride deposition temperature for this run is 280°C, very close to the nominal 300 °C at which the reactor effluent is maintained before water injection. Hold-up of chlorine as ammonium chloride also explains the lower nitrogen recoveries, compared with Runs 3 and 4.
• FIG. 14 A schematic diagram of the hydrotreater is given in Figure 14.
• the reactor, Figure 15, consists of five heated zones, each having individual controllers.
• a series of detecting thermocouples, embedded in the catalyst enabled the temperature gradient to be monitored while the rig was operational.
• the reactor was packed with 90 g of catalyst (Cyanamid HDN-60 1.6 mm Trilobes) dispersed along the reactor length between heating zones 1 and 5, the remaining volume of reactor was packed with silicon carbide (1.4 mm), the packing material was supported from the bottom by a stainless steel gauze cylinder.
• the catalyst was presulfided as described in Section A 1.3. Hydrogen is pressurised and delivered to the hydrotreater, its flow rate being regulated by the Brooks Flow Controller.
• Feed is pumped into the system and passes through the heated catalyst bed.
• Water normally 5 wt% of feed oil
• the temperature of this region is maintained at 300° C.
• the product stream is then cooled to 30 °C prior to separation of the liquid and gaseous phases.
• a series of air actuated solenoid valves were incorporated into the rig design.
• SV3 and SV5 are closed, and products collect in the lower trap.
• SV2 and SV4 are closed, isolating the lower trap, SV5 is opened and the pressure vented to approximately 1.4 MPa.
• SV5 is closed, SV3 opened and the retained pressure used to expel the liquid products.
• SV3 is then closed, SV5 is reopened and the lower trap repressurised with helium to operational pressure.
• SV2 and SV4 are then reopened.
• the temperature of the lower trap was kept at 30°C.
• off-gas samples were collected for analysis. These samples were collected into 5L cyanamide gas bags down stream of the back pressure regulator by manually switching the valve from vent' to N gas collection'.
• the gas flow out of the hydrotreater was also measured at this point using a Lapszewicz gas flow device (J.A. Lapszewicz, "Device for measurement of volumetric flow rates", Meas. Sci. Technol. 2 (1991) 815-817).
• Computer controlled solenoids directed the gas flow from vent' to " measure' , by using infra red emitters and sensors the gas flow was determined by displacement of a known volume of water at atmospheric pressure.
• Catalyst activation was carried out under hydrogen at a pressure of 5 MPa.
• the feed used was 850g toluene, to which 51g of dimethyldisulfide had been added. After pressurising the system and establishing the hydrogen flow, feed was introduced at a rate of 84.5 ghr "1 .
• the temperature was then incremented 25°C every 30 minutes to 250°C, and held at this point until hydrogen sulfide could be detected in the off-gas using Drager tubes. After detection of the hydrogen sulfide, the temperature was increased in stages of 25°C (ensuring a breakthrough of H 2 S each time) to 350°C.
• Trials 14 and 15 employed a factorial experimental design, varying temperature, pressure and space velocity around a centre point of 340°C / 3.5MPa / 2.0 hr "1 , which to assess the catalyst aging was carried out at the beginning, middle and end of these trials.
• the feed used in Run 1 was a typical oil for regeneration.
• the total chlorine level and PCB content of the oil were 19.1 mg/kg and 24 mg/kg respectively.
• the feed used in Run 2 was the same feed oil used in Run 1, with an added 200 mg/kg of PCB.
• the PCB used was Type 1016, drained from a Plessy Type APF 265 OR capacitor. The order in which different conditions were carried out is iven below:
• Run 2 a twelfth condition was introduced (340 / 3.5 / 3). At the commencement of Runs 1 and 2, an equilibration interval of 2 hours was allowed, during which time 4 samples were taken. After these equilibration samples were collected, 3 steady state samples were collected, (A, B and C) each in 2 sub-parts, over a period (determined by the space velocity) to yield the required weight of sample for analysis. After collection of the three steady state samples, condition parameters were changed and the system again allowed to stabilize for a period determined by the space velocity prior to collection of the next steady state samples.
• Run 3 was to be an extended run at the optimum processing conditions (indicated by the results of Runs 1 and 2) designed to both test catalyst stability and to produce sufficient volumes of oil for larger scale test work.
• the feed to be used in Run 3 was the same as that used in Run 1, that is, with no added PCB.
• Run 3 was terminated prematurely, therefore, the intended test of catalyst stability was unable to be determined. For this reason the intended length of Run 4 was increased.
• the feed for this run contained 200mg/kg added PCB.
• Ammonia Gas samples for analysis were collected from the hydrotreater at the collection point shown in Figure 14. 5 L of gas was collected as close to the end of the relevant sampling period as possible. Ammonia levels were determined using a Drager Tube.
• Dielectric Dissipation Factor Dielectric Dissipation Factor Dielectric dissipation factors were obtained by using IEC 247, "Measurement of relative permittivity, dielectric dissipation factor and d.c. resistivity of insulating liquids" (see
• Hydrogen consumptions were calculated using the difference between the gas flow in, measured on the calibrated Brooks Flow Controller, and the gas flow out, measured on the
• Injector temperature 160°C; TCD Detector temperature : 220°C; Filament temperature : 250°C; Sensitivity Range : 0.05; Flow 30 ml/min; Injection volume 250 ⁇ L.
• Boiling-point distribution of the oil analysed was obtained by processing slice data from the chromatography run. This calculation was conducted using Lotus-123 software on an IBM- PC C.17.
• the process can be adapted and used to destroy other chlorinated toxic materials such as DDT, dioxin and HCB with single pass decontamination factors > 99.999%.
• Another application of the technology will be for the clean up of capacitors contaminated with PCBs. This market is estimated to be a minimum of 210 tonnes of PCBs.
• a further application of this new technology relates to the destruction of PCBs and similar compounds formed during the production of magnesium and titanium metals. It is expected that production of magnesium metal will become a major new Australian industry, based on the recently discovered Kunwarara magnesite deposit. It is being developed with substantial federal and state government support. Current plans envisage production of up to 240,000 tonnes of magnesium metal per annum. Such a size plant will produce substantial quantities of PCBs, HCBs and other similar chlorinated organic compounds. At present, the disposal of so much waste is a major problem. The process of the present invention is ideally suited for destroying this waste and could, moreover, be easily integrated into the overall process flowsheet.

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