Abstract: A method for producing a process oil is provided in which an aromatic extract oil is added to a naphthenic rich feed to provide a blended feed. The blended feed is then extracted with an aromatic extract solvent to yield a raffinate which subsequently is hydrotreated to provide a process oil.

Abstract: The wax-containing hydrocarbon feedstocks are pre-treated by contacting them with a homogeneous solution containing 1-5 vol. % of an acid diluted in an alcohol/water mixture (preferably containing 60-90 vol. % alcohol). The pre-treated feedstock is then contacted, in the presence of hydrogen, with at least two catalysts in sequence and with no intermediate separation, comprising at least one hydrodewaxing catalyst and one hydrocracking catalyst, to recover high-grade middle distillates.

Abstract: A process is provided for the recovery of hydrogen chloride in anhydrous form from a dry (containing less than about 500 parts per million by weight of water) mixture of hydrogen chloride with one or more non-condensable gases and which may also contain components heavier than hydrogen chloride, which process comprises distilling the mixture to produce an overheads stream containing the non-condensable gases and about 95 percent or more by weight of the hydrogen chloride in the mixture and a bottoms stream containing about 95 percent or greater by weight of all components heavier than hydrogen chloride, and compressing and refrigerating the overheads stream whereby a selected proportion of the hydrogen chloride in the overheads stream is produced in a liquid anhydrous form containing less than about 50 parts per million by weight of water.

Abstract: In a solvent recovery plant including a recovery or distillation tower from which solvent product is recovered overhead, an isothermal separator, preferably a cyclone, is used to separate liquid phase contaminant (i.e. oil in a lubricating oil extraction process) in overhead product and to feed the separated liquid to the recovery tower as reflux. In addition, a portion of the feed to the tower can be branched off and mixed with the overhead product to bring its temperature down to close to the dew point of the solvent vapor. In this way, flooding of the uppermost tower trays and distillation of oil overhead can be overcome.

Abstract: The invention provides for a process for producing lube oil having excellent viscosity and viscosity index properties and a low pour point from a solvent refined gas oil. The process comprises contacting a raffinate having a solvent dewaxed viscosity index of at least 90 and boiling above 350.degree. F. with a catalyst comprising an intermediate pore size silicoaluminophosphate molecular sieve and at least one Group VIII metal under dewaxing and isocracking conditions so as to produce a product having a viscosity index greater than about 110.

Abstract: A process for feed oil refining for production of lubricating oil, by using an equipment for lubricating oil production including a fulfural refining unit, a hydrotreating unit and a ketone dewaxing unit, all connected in series. In this process, operations associated with the switch of feed oil are conducted by carrying out the first to seventh step groups successively. Each step group is initiated when a given time has passed since the start of the previous step group, or when the value of a particular measurement item has reached a target value, or when the value of a particular measurement item has shown a change. First, in the first step group, the amount of feed oil supplied to each unit, etc. is adjusted and, in the second step group, the feed oil to the furfural refining unit is switched.

Abstract: Low sulfur gasoline is produced from a catalytically cracked, sulfur-containing naphtha by fractionating the naphtha feed into a low boiling fraction in which the majority of the sulfur is present in the form of mercaptans and a high-boiling fraction in which the sulfur is predominantly in non-mercaptan form such as thiophenes. The low boiling fraction is desulfurized by a non-hydrogenative mercaptan extraction process which retains the olefins which are present in this fraction. The second fraction is desulfurized by hydrodesulfurization, which results in some saturation of olefins and loss of octane. The octane loss is restored by treatment over an acidic catalyst, preferably an intermediate pore size zeolite such as ZSM-5, to form a low sulfur gasoline product with an octane number comparable to that of the feed naphtha but which contains some recombined sulfur in the form or mercaptans which are removed in the non-hydrogenative mercaptan extraction step.

Abstract: A resid hydrotreating process hydrotreats a resid bottoms fraction from the reduction of crude oil. The hydrotreated bottoms fraction is then subjected to deep vacuum reduction and in some cases deasphalted by solvent extraction to produce an oil suitable for use as a catalytic cracking feedstock and a resins fraction suitable for solvating resid in a hydrotreating process.

Abstract: Hydrocarbon lubricants having a high viscosity index (V.I.) and low pour point are produced by hydroisomerizing, over zeolite beta, a waxy lube feed such as a waxy vacuum gas oil whose aromatic components are removed by extraction, e.g. with furfural. The zeolite beta catalyst comprises noble metal, e.g., Pt, and a low acidity zeolite beta, e.g., framework boron-containing zeolite beta.

Abstract: An automatic transmission fluid basestock of mineral oil origin is produced from a neutral distillate fraction, preferably a medium neutral distillate, by severe furfural extraction to a dewaxed oil equivalent VI of about 95, severe hydrocracking, at temperatures ranging from at least about 700.degree. F. and pressures of at least about 1,500 psig, to achieve a minimum product VI of 120. The hydrocracked product is vacuum distilled to recover a lubricant oil product boiling above about 650.degree. F. which has a VI of at least 120 and a viscosity at 100.degree. F. of at least 100 SUS. The viscosity of the 120 VI product can be increased by increasing the distillation cut point without impacting the VI. The lubricant oil, having a wax content below 30 wt. %.

Abstract: A process is provided for producing premium and super premium grade needle coke comprising the steps of passing a heavy resid feedstock to a resid hydrotreating reaction zone at resid hydrotreating conditions and producing light resid hydrotreated products and a heavy resid hydrotreated residual product, directing the heavy resid hydrotreated residual product and FCC decanted oil to a solvent extraction process reaction zone at solvent extraction process conditions and producing products comprising a solvent extracted oil and resin stream and a stream comprising asphaltenes, and conveying at least a portion of the solvent extracted oil and resin stream to a delayed coking process at delayed coking conditions and producing liquid products and premium grade coke.

Abstract: A method for reducing the pour point of a hydrocarbon feedstock that contains aromatic compounds, sulfur-containing compounds and nitrogen-containing compounds is provided. The method involves solvent extraction and utilizes a catalytic hydrodewaxing zone with a first section having a shape-selective molecular sieve-containing catalyst composition which is substantially free of Group VIII metals and a second section having a Group VIII metal-containing hydrogenation catalyst composition with a porous support material substantially free of acidic crystalline molecular sieve material.

Abstract: Turbine oils are produced from a distillate lube fraction by hydrocracking to remove aromatics, catalytically dewaxing, hydrofinishing then treating with an organic peroxide, such as ditertiary butyl peroxide (DTBP) to increase viscosity and reduce cloud point.

Abstract: A process for improving the performance of heavy oil refining units in a resid hydrotreating unit equipped for resid hydrotreating. The partially refined resid stream issuing from a train of ebullated bed reactor is first separated into high, medium, and low temperature components. The high temperature component is sent through a flash drum and then fractionated by solvent deasphalting in order to provide oil, resin, and asphaltene fractions. Thus, the asphaltene is eliminated before it can foul downstream equipment. This treatment of the heavy oil product has several benefits as compared to treating the vacuum tower bottoms. Among other things, one of these benefits is to debottleneck the resid hydrotreating unit, especially at the atmospheric tower.

Abstract: Catalytic Cracking is effected by feeding thereto (i) a deasphalted vacuum resid together with (ii) a solvent treated virgin vacuum gas oil, the two being preferably mixed prior to solvent treating.

Abstract: The invention reduces cracking catalyst fines in decanted oil by mixing the decanted oil (DCO) containing cracking catalyst fines with a resid oil and then treating the DCO-resid mixture with a non-aromatic hydrocarbon solvent in an extraction unit or in a multi-stage deasphalting unit.

Abstract: The invention reduces cracking catalyst fines in decanted oil by mixing the decanted oil (DCO) containing cracking catalyst fines with asphaltene and then treating the DCO-asphaltene mixture with a non-aromatic hydrocarbon solvent in an extraction unit or in a multi-stage deasphalting unit.

Abstract: The invention reduces cracking catalyst fines in decanted oil by mixing the decanted oil (DCO) containing cracking catalyst fines with asphaltene and then treating the DCO-asphaltene mixture with a non-aromatic hydrocarbon solvent in an extraction unit or in a multi-stage deasphalting unit.

Abstract: A process is described for removing mineral or ash constituents from heavy hydrocarbon residues, such as those resulting from coal-oil coprocessing, residue hydrocracking or coal liquifaction. The process comprises the steps of: (a) intimately mixing the ash-containing heavy hydrocarbon oil residue with a surfactant and a pH-conditioned aqueous solution under high shear mixing conditions to disperse the ash-containing residue in the aqueous phase thereby creating a fine oil-in-water emulsion, (b) adding a strong oxidizing agent to the emulsion to thereby break the emulsion and release the ash into the aqueous phase and (c) separating the ash-containing aqueous phase from the oil phase. The HLB method for characterizing the emulsion forming activity of a surface active material is described in M. J. Rosen, Surfactants and Interfacial Phenomena, John Wiley & Sons, New York (1989), incorporated herein by reference.

Abstract: A method for processing heavy crude oils comprising a) atmospheric distillation of a heavy crude oil having a high content of metals, asphaltenes and sulfur; b) solvent extraction of the atmospheric distillation residue to obtain an extract with characteristics equivalent to those which an atmospheric residue derived from light crude oil and a raffinate fraction, solid at ambient conditions, in which are concentrated the asphaltenes, metals and sulfur present in the original crude oil; c) vacuum distillation of the deasphalted extract, obtaining a light fraction or gas oils with characteristics adequate to be subjected to a secondary conversion process, plus a bottoms fraction or vacuum residue; d) treatment of the vacuum gas oils in a conversion stage and e) subjecting the bottoms of raffinate from the extraction stage to a metallurgical process, in admixture with cokeable coal and coke fines to production of metallurgical coke.

Abstract: A lubricating oil stock is extracted with N-methyl-2-pyrrolidone to yield a primary raffinate useful as a high VI lubricating base oil and a primary extract. The primary extract is mixed with antisolvent and chilled to yield a secondary raffinate. This secondary raffinate is sufficiently reduced in aromatics that it is suitable for fluidized catalytic cracking in the absence of hydrogenation.

Abstract: A lubricating oil stock is extracted with N-methyl-2-pyrrolidone to yield a primary raffinate useful as a high VI lubricating base oil and a primary extract. The primary extract is mixed with antisolvent and chilled to yield a secondary raffinate. This secondary raffinate is sufficiently reduced in aromatics that it is solvent extracted to yield medium to high VI lubricating base oil.

Abstract: Non-carcinogenic bright stock extracts and/or deasphalted oils are produced from reduced hydrocarbon feedstocks. Such non-carcinogenic products are produced by establishing a functional relationship between mutagenicity index and a physical property correlative of hydrocarbon type for the bright stock extract or deasphalted oil and determining a critical physical property level which, when achieved, results in a product having a mutagenicity index of less than about 1.0. Process conditions are established so that a product stream achieving the desired physical property level can be produced. Non-carcinogenic bright stock extracts and/or deasphalted oils are then processed utilizing the conditions so established. A bright stock extract and a deasphalted oil substantilly free from mutagenic activity, as well as processes for their production are also provided herein.

Abstract: Heavy hydrocarbon oil, containing asphaltene, sulfur and metal contaminants, is hydrotreated in the presence of a hydrotreating catalyst having a small pore diameter in an initial process step to remove sulfur and metal contaminants. Removal of additional metal and sulfur contaminants is then accomplished in a second process step by solvent deasphalting, wherein the size of the pore diameter of the hydrotreating catalyst utilized in the initial hydrotreating step affects the metals rejection in the subsequent solvent deasphalting step. In a third process step the deasphalted oil is catalytically cracked substantially in the absence of added hydrogen to provide lower boiling hydrocarbon products.

Abstract: The invention relates to a process for hydrocarbon fractionation and extraction making it possible to obtain a petrol with an improved octane number and a kerosene with an improved smoke point.According to the invention a charge with a final boiling point of at least 220.degree. C. is fractionated into three fractions:a light petrol containing less than 10% aromatics and boiling points at 25.degree. to 80.degree. C.,a medium petrol (80.degree. C. and at the most 150.degree. C.), whose end point is determined by a nitrogen content below 50 ppm,a heavy petrol with an end point equal to or below 220.degree. C.,be a selective liquid solvent aromatics are then extracted from the heavy petrol producing a refined product which is poured into the kerosene pool or diesel fuel,the solvent is regenerated by reextraction using light petrol so as to produce an aromatics-enriched petrol fraction with an improved octane number.

Abstract: Turbine oils are produced from a distillate lube fraction by solvent extraction to remove aromatics, e.g., with furfural, then dewaxing and hydrofinishing to saturate residual aromatics. Treatment with an organic peroxide, such as ditertiary butyl peroxide (DTBP), increases viscosity to compensate for the viscosity loss during the hydrofinishing. Dewaxing may be solvent or catalytic dewaxing or both. Peroxide treatment also reduces cloud point.

Abstract: A hydrotreating process if provided in which resid and resins are hydrotreated with hydrogen-rich gases in the presence of a hydrotreating catalyst in an ebullated bed reactor.

Abstract: The quality and yield of dewaxed, hydrotreated lube oil base stocks are improved by reducing the top temperature in the hydrotreated lube stripper so as to increase the proportion of heavy kerosene components in the lube oil base stock. The separation system provides for a two stage stripping of the lube oil fraction such that the kerosene fraction stripped from the lube product in the primary product stripper under vacuum is stripped in a second stage stripper at a higher pressure with recycle of the heavy kerosene fraction as a reflux stream to the primary vacuum stripper so that a product with improved viscosity index and flash point is separated in the primary stripper.

Abstract: A method of reducing the concentration of metal contaminants, such as vanadium and nickel, in distillates of a fossil fuel feedstock is disclosed. The method comprises producing a selected distillate fraction and demetallizing this distillate by suitable means, thereby upgrading and making it suitable for use as feed to a catalytic cracker.

Abstract: A process is provided in which solvent-extracted oil or other deasphalted oil derived from hydrotreated resid is catalytically cracked to increase the yield of gasoline and other high value products.

Abstract: This invention provides a method for extending the catalytic dewaxing cycle time of a refined waxy lube stock. The method, in its broadest aspect, requires the additional refining step of thermally treating the refined waxy stock or precursor thereof for about 0.1 to about 2.0 hours at elevated temperature and at a pressure of 0 to 3000 psig (pounds per square inch gauge), and recovering an upgraded waxy stock having a reduced content of trace compounds that contain metals, nitrogen, sulfur and oxygen.In a specific embodiment of this invention, a vacuum residuum is thermally treated at a temperature of about 700.degree. F. to 950.degree. F. prior to solvent deasphalting and solvent extraction, and the waxy bright stock so formed is catalytically dewaxed with extended cycle time.

Abstract: A method and apparatus for a combined solvent and hot water extraction of bitumen oils from tar-sands ore. The crushed tar-sands ore is conditioned in hot water while excluding air, after which oversized and inert rocks are removed by screening. The bitumen content of the resulting slurry is then extracted with a water immisible hydrocarbon solvent of low density to form a solution of bitumen oils in solvent or bitumen extract phase, a middle water phase and a lower spent wet solids phase. Each of these phases is thereafter processed to produce product bitumen oils and to recover solvent and water for reuse within the process. The product bitumen oils are further processed to separate the fines, and may be refined and separated into synthetic crude oil and asphaltenes residue components. The asphaltenes residue component may be burned in a fluidized bed boiler to provide process heat and electrical power for the method.

Abstract: The control system and method of the present invention controls a solvent refining unit which treats charge oil with a solvent in a refining tower to yield raffinate and extract-mix, strippers separate the solvent from the raffinate and from the extract-mix to provide refined waxy oil and extract oil, respectively. The solvent is returned to the tower and the refined waxy oil is subsequently dewaxed to provide refined oil. The present invention includes a device which senses the flow rate of the charge oil and provides a corresponding charge oil flow rate signal. The flow rate of the charge oil is controlled in accordance with the charge oil flow rate signal and a control signal. The temperature of the extract oil is sensed and a corresponding temperature signal provided. The temperature signal is used in controlling the temperature of the extract oil in cooperation with a second control signal.

Abstract: An effective, economical catalytic cracking process is provided to produce quality gasoline and other hydrocarbons from whole crude oil. The catalytic cracking process is operable and particularly useful during maintenance or shutdown of associated pipestills, vacuum tower, and/or atmospheric tower.

Abstract: A process is disclosed for eliminating waxy paraffins from hydrocarbon feedstocks having an initial boiling temperature above about 180.degree. C. and containing sulphur, by selective cracking of the straight chain paraffinic hydrocarbons, said process comprising passing said feedstock over a crystalline silica polymorph of the silicalite type under suitable operating conditions for cracking the straight chain paraffins.

Abstract: We disclose a single stage, multilayered catalyst system capable of hydrodewaxing and hydrofinishing a solvent-dewaxed lube oil base stock. In the first layer we catalytically dewax the solvent-dewaxed stock. In the second layer we hydrofinish the catalytically dewaxed stock. Our invention also relates to a process for hydrodewaxing and hydrofinishing a solvent-dewaxed lube oil base stock.

Abstract: A process is disclosed for the working up of salvage oil, in which the salvage oil is subjected to an extraction under supercritical conditions. The halogen compounds contained in the produced extract are removed by catalytic hydrogenation. The extraction residue is eliminated by deposition or thermal treatment (gasification). In the case of a thermal treatment of the extraction residue, other residues can be simultaneously converted, so that the process is performed without yield of environmentally burdensome residues or by-products. Ethane in particular and/or propane is employed as solvent for the supercritical extraction.

Abstract: A process is disclosed for the removal of basic heterocyclic nitrogen compounds from a petroleum crude oil or fraction thereof which comprises first treating the petroleum crude oil or fraction thereof rich in basic heterocyclic nitrogen compounds in a two-phase extraction zone with an extractant consisting essentially of an aqueous solution of a lower carboxylic acid, preferably having between 1 and 15 carbon atoms. The extractant complexes the basic heterocyclic nitrogen compounds to produce a stream of petroleum crude oil or fraction thereof having a smaller content of heterocyclic nitrogen compounds and a stream comprising the lower carboxylic acid extractant with an increased quantity of basic heterocyclic nitrogen compounds. The petroleum crude oil or fraction thereof possessing a reduced quantity of heterocyclic nitrogen compounds is hydrotreated in the presence of hydrogen and a hydrotreating catalyst to further remove the basic heterocyclic nitrogen compounds.

Abstract: A process for producing a lubricant base oil with low pour point and high aromaticity from a feedstock oil which is either a distillate fraction boiling at 250.degree. C. or above that is obtained from a paraffin base or mixed base crude or a deasphalted oil obtained from a vacuum distillation residual oil of said crude, and process comprising:(a) the step of bringing said feedstock oil into contact with a hydrofining catalyst in the presence of hydrogen and recovering a hydrofined oil;(b) the step of dewaxing said hydrofined oil and recovering the dewaxed oil;(c) the step of subjecting said dewaxed oil to extraction with a solvent having selective affinity for aromatic hydrocarbons so as to separate the feed into the raffinate portion and the extract portion, and removing the solvent from said extract portion to obtain an extract oil; and(d) the step of treating said extract oil by means of contact with a solid adsorbent or sulfuric acid.

Abstract: Prior to upgrading a viscous feed by visbreaking, at least a portion of the feed is treated to remove a heavy phase in specified amounts, whereby the severity of the visbreaking may be increased. The Shell Hot Filtration number of the visbreaking product is reduced by at least 75%, compared to visbreaking of untreated feed at some severity.

Abstract: Process for the manufacture of lubricating base oils from nitrogen-containing distillate and/or deasphalted oils by catalytic hydrotreatment followed by a dewaxing treatment, which comprises subjecting nitrogen-containing distillates and/or deasphalted oils to solvent extraction and subjecting the raffinate and/or the extract produced to a further treatment to obtain a low-nitrogen fraction and a high-nitrogen fraction and subjecting the low-nitrogen fraction from the extract and/or the high-nitrogen fraction from the raffinate to catalytic hydrotreatment.

Abstract: The present invention provides for a process for reducing the pour point of a hydrocarbon feedstock containing nitrogen- and sulfur-containing impurities. The hydrocarbon feedstock is contacted with hydrogen and a hydrotreating catalyst under hydrotreating conditions whereby a portion of the nitrogen- and sulfur-containing compounds are converted to hydrogen sulfide and ammonia. A portion of the hydrotreater effluent is then passed to a dewaxing zone and contacted with hydrogen under dewaxing conditions in the presence of a borosilicate-containing dewaxing catalyst.

Abstract: The present invention provides for a process for reducing the pour point of a hydrocarbon feedstock containing nitrogen- and sulfur-containing impurities. The hydrocarbon feedstock is contacted with hydrogen and a hydrotreating catalyst under hydrotreating conditions whereby a portion of the nitrogen- and sulfur-containing compounds are converted to hydrogen sulfide and ammonia. A portion of the hydrotreater effluent is then passed to a dewaxing zone and contacted with hydrogen under dewaxing conditions in the presence of a dewaxing catalyst containing a borosilicate molecular sieve on silica-alumina-containing matrix.

Abstract: A delayed coking process and a solvent deasphalting process are combined so that an asphalt mix of asphalt and solvent from the solvent deasphalting process is sent as feedstock to the delayed coking process to form coke and intermediate hydrocarbon vapor and liquid products. The vaporization of the solvent in a delayed coker heater assists the flow of the asphalt mix through the heater, and a portion of the asphalt mix is directed to a delayed coking fractionator so that the flow of solvent through the delayed coking heater can be adjusted by varying the relative amounts of asphalt mix sent to the delayed coker heater and to the fractionator. A deasphalted oil mix of deasphalted oil and solvent from the solvent deasphalting process is heated by hotter fluid products from a fractionator in the delayed coking process, and makeup solvent to a solvent deasphalting section is heated by vapors in the fractionator overhead.

Abstract: Multi-step synergistic process for converting waxy-containing hydrocarbon feedstocks to lube oil stocks having targeted pour points is disclosed. The waxy feed is first catalytically partially dewaxed with the catalyst having the structure of ZSM-5, and then the partially dewaxed oil is subjected to solvent dewaxing to reach a targeted pour point. Pretreating the crude prior to catalytic dewaxing process such as by deasphalting and aromatic removal is also disclosed. In an alternative process, the waxy-containing hydrocarbon feed is subjected to the steps of solvent dewaxing, catalytic dewaxing, and solvent dewaxing.

Abstract: A process in fuels production for increasing the yield of deasphalted oil production from upgraded residua and improving deasphalter operability involving mixing the upgraded residua with an aromatics solubilizing aid to prevent the formation of an immiscible third phase during deasphalting.

Abstract: The present invention provides for a process for reducing the pour point of a hydrocarbon feedstock containing nitrogen- and sulfur-containing compounds. Specifically, the hydrocarbon feedstock is passed to an extraction zone wherein N-Methyl-2-pyrrolidone is used to extract a portion of the aromatic compounds. A portion of the extraction zone raffinate is then passed to a hydrotreating zone wherein a portion of the nitrogen and sulfur containing compounds are converted to hydrogen sulfide and ammonia. Subsequently, a portion of the hydrotreating zone effluent is then passed to a dewaxing zone and contacted with a shape selective molecular sieve containing dewaxing catalyst.

Abstract: Apparatus is disclosed for oligomerizing olefinic Fischer-Tropsch liquids to produce heavier hydrocarbons by converting olefinic feedstock containing oxygenated hydrocarbons over an acidic zeolite catalyst. The improvement comprises an extraction unit for removing oxygenates from the feedstock; means for converting the extracted feedstock in a primary stage distillate mode catalytic reactor system under low severity conditions at high pressure and moderate pressure; means for recovering the oxygenates and light hydrocarbons from the primary stage and a secondary stage reactor system for conversion of oxygenates under high severity conditions at substantially higher temperature than the primary stage, thereby converting oxygenates and light hydrocarbons to heavier hydrocarbons.

Abstract: A process is disclosed for the manufacture of lubricating base oils from nitrogen-containing distillates and/or deasphalted oils by subjecting them to a catalytic hydrotreatment which may be followed by a dewaxing treatment, wherein distillates and/or deasphalted oils having a nitrogen content which numerically expressed exceeds the value f.multidot.P.sub.H2 .multidot.S.sub.v.sup.-1, wherein f is a constant relating to the viscosity of the final base oil, P.sub.H2 represents the hydrogen partial pressure in bar applied in the catalytic hydrotreatment and S.sub.v represents the weighted hourly space velocity in t/m.sup.3 .multidot.h at which the catalytic hydrotreatment is carried out, are subjected to a preceding solvent extraction.

Abstract: This invention discloses an economic series flow dewaxing scheme having a first solvent dewaxing step followed by a catalytic dewaxing step. The use of methylisopropyl ketone as a key component in the solvent dewaxing step produces a solvent dewaxed effluent with an intermediate pour point which may be readily catalytically dewaxed to a pour point suitable for lubricant applications. The catalytic dewaxing unit can also be used to recover lost oil yield from the soft wax product of the solvent dewaxing zone (sometimes referred to as footsoil) and thereby sustain, if not increase, overall lubricating oil yield.