Abstract: Provided are high activity catalysts based upon gamma alumina containing substrates impregnated with one or more catalytically active metals which catalysts in addition contain a nanocrystalline phase of alumina of a crystalline size at the surface of less than 25Å. Also provided are processes for preparing such high activity catalysts and various uses thereof.

Abstract: A method is described for improving the catalytic performances of titanium silicalite having formula (I) by the activation of the catalyst (I) in an aqueous medium with hydrogen peroxide, in the presence of precursors of fluoride ions or anionic species containing fluorine. The activated catalyst (I) is particularly useful in oxidation processes with hydrogen peroxide of organic substrates and, in particular, in hydroxylation reactions of aromatic compounds, amoximation reactions of carbonyl compounds, epoxidation reactions of olefinic compounds and oxidation reactions of nitrogenated compounds.

Abstract: The method for rejuvenating solid paraxylene adsorbent comprises the steps of varying the water injection rate above a predetermined minimum level in a non-linear fashion for a time sufficient to produce rejuvenation of the adsorbent and if desired, adding at least one polar organic compound to the water being injected.

Abstract: Disclosed are a self-catalytic bath and a method for the deposition of Ni—P alloy on a substrate. The bath comprises nickel sulfate, sodium hypophosphite as a reducing agent, acetic acid as a buffer and traces of lead as a stabilizer. It also includes a citrate used as a complexing agent associated with a gluconate used both as a catalyst and a stabilizer. The disclosed bath makes it possible to tolerate large quantities of hypophosphite and is relatively long-lived. Furthermore, it can be used to prepare large quantities of Ni—P alloy per liter of solution.

Abstract: A process for the desulfurization, and reactivation of a sulfur deactivated catalyst constituted of cobalt composited with a titania support. The sulfur deactivated cobalt titania catalyst is first contacted with a gaseous stream of molecular oxygen at temperature sufficiently high to oxidize the sulfur component of the catalyst. The sulfur oxidized catalyst is next contacted with a liquid, preferably water, to remove the oxide, or oxides of the sulfur. The catalyst is then contacted with a reducing agent, suitably hydrogen, to restore the activity of the catalyst. During the treatment there is no substantial loss, if any, of cobalt from the catalyst.

Abstract: A method for washing a spent solid catalyst is disclosed which is characterized by washing the solid catalyst used for the reaction of generating an esterified compound in a device packed with the solid catalyst, distilling the cleaning fluid in a distilling part, and circulating the fraction obtained by the distillation to an esterification reactor. According to this invention, the existing apparatus used during the process for the production of an esterified compound can be adopted without any modification, the water by-produced in the reaction for production an esterified compound and an alcohol as the raw material for esterification can be used as the cleaning fluid, and these effective components can be recovered from the cleaning fluid. Thus, the stimulation from the offensive odor and the volatile component which has heretofore posed a problem during the removal of the solid catalyst is eliminated and the safety in terms of heath and in terms of operation is secured.

Abstract: The present invention provides a method for maintaining temperature during regeneration of an oxygenate to olefins catalyst using liquid water as a coolant in an amount sufficient either to reduce duty of a catalyst cooler or to avoid the need to use a catalyst cooler altogether. The method also may be used to hydrotreat fresh, non-hydrothermally treated catalyst which may be added to the regenerator and charged back to the conversion reactor along with the regenerated catalyst.

Abstract: Provided are high activity catalysts based upon gamma alumina containing substrates impregnated with one or more catalytically active metals, which catalysts in addition contain a nanocrystalline phase of alumina of a crystalline size at the surface of less than 25 Å. Also provided are processes for preparing such high activity catalysts and various uses thereof.

Abstract: The invention concerns a method of cleaning and/or regenerating wholly or partially de-activated catalysts for stack-gas nitrogen scrubbing, in which the catalysts are treated with a washing and/or regenerating liquid, characterized by the washing or regenerating liquid consisting wholly or in part of demineralized water.

Abstract: This invention relates to a method of improving the catalytic performance of palladium or ruthenium, rhenium-on-carbon hydrogenation catalysts operating in aqueous media where loss of soluble rhenium may result in rapid catalytic failure. A rhenium-containing hydrogenation catalyst comprised of rhenium on a support material is regenerated by first treating the catalyst with aqueous perrhenic acid or potassium perrhenate followed by treating the catalyst under reducing conditions at elevated temperature and pressure. Treatment of the catalyst as described replenishes dispersed fresh finely divided rhenium which enhances the activity of the catalyst while at the same time allowing the operations to be carried out in situ in the hydrogenation reactor or in a side stream reactor with significant savings in reducing reactor down time and precious metal expenses.

Abstract: A process is disclosed for the recovery of gold and/or silver values from activated carbon, wherein they are adsorbed as cyanide complexes. The process uses an eluant containing sugar. The process allows the eluant to pass through fresh carbon twice, thereby reducing the volume of the gold-loaded eluant. This, in turn, reduces the size of the electrowinning or zinc precipitation circuits. The process also improves elution efficiency when barren electrowinning solution is recycled in the elution process.

Abstract: A method for efficient reclamation of metal catalyst species from aqueous extract streams diaryl cabonate synthesis, comprising treating a metal-containing aqueous extract stream of a mixture from the production of diaryl carbonates with a precipitating agent effective to selective precipitate one or more metal catalyst species from the extract. Use of these methods substantially reduces both financial and environmental concerns for the preparation of diaryl carbonates.

Abstract: Contaminated adsorbent particles, preferably activated carbon particles, are regenerated in water at supercritical conditions. The particles are preferably mixed in water prior to treatment. The mixture is preferably heated to a temperature at least about 900.degree. F. (482.degree. C.) and pressurized to a pressure sufficient to achieve supercritical conditions for water. The mixture is preferably flowed through a first reactor for a time sufficient to substantially remove the organic contaminants from the particles. The particles are separated from the water and the mixture of water and organic contaminants may be transferred to a second reactor. Within the second reactor the organic contaminants are preferably substantially oxidized by supercritical water oxidation.

Abstract: A process for recovering metal from spent catalyst, containing at least a metal component, comprising providing a heated, liquid metal bath, at a temperature sufficient to melt the metal in the spent catalyst, and create off gas from any volatile non-metal catalyst components, adding spent catalyst to the bath, collecting off gas from the bath, transporting the collected off gas to a gas cooler, and maintaining the off gas during the transportation at a temperature of at least about 875.degree. F.; rapidly cooling the off gas to less than about 275.degree. F. in no more than about 0.15 seconds, to prevent the formation of dioxin; and withdrawing melted metal from the bath, for reuse as catalyst.

Abstract: A method of separating a Fischer-Tropsch catalyst from the output slurry of a Fischer-Tropsch bubble column reactor, where the slurry comprises Fischer-Tropsch catalyst particles and liquid hydrocarbon product is disclosed. The method comprises contacting a compressed hydrocarbon solvent (e.g., a supercritical hydrocarbon solvent, or liquid hydrocarbon solvent which may be at near supercritical conditions) with the output slurry at a temperature and pressure where the liquid hydrocarbon product is soluble in the solvent to form a concentrated slurry phase containing the catalyst particles, and an enriched solvent phase containing liquid hydrocarbon product. This contacting step is then followed by the step of separating the concentrated slurry from the enriched solvent. Apparatus for carrying out the method of the invention is also disclosed.

Abstract: A process serves for recoating a deactivated catalyst coating of a catalyst for converting harmful constituents from the exhaust gas of an internal combustion engine, particularly in a motor vehicle. In this process, washcoat and/or noble metal compounds are sprayed by means of an aerosol into the catalyst. The noble metal compounds are subsequently brought into their elemental state by means of a reducing medium flowing through the catalyst, after which the washcoat applied is dried by heat treatment or calcination. In an apparatus for carrying out the process, a first line for a carrier gas and a second line for the washcoat and/or the noble metal compounds are provided. The first line is arranged at least partly in a region before the catalyst within the second line and at its ends nearest the catalyst is provided with an atomization device.

Abstract: An improved process is provided for the recovery of catalyst components from oligomeric impurities which are formed during the industrial preparation of 2,5-dihydrofuran by the catalytic isomerization of vinyl oxirane followed by an essential separation of the oligomeric by-products which otherwise cause deactivation of the catalyst. The catalyst components consist essentially of (a) an onium iodide and (b) a Lewis acid selected from the group consisting of the chloride, bromide or iodide of the metals zinc, tin, cobalt and bismuth, preferably zinc, where the catalyst optionally includes a donor ligand.

Abstract: Methods are disclosed for the regeneration of fouled ion exchange (IX) resins. In one embodiment, the fouled resin is treated simultaneously with reducing agent and acid. In a preferred embodiment, fouled resin is treated with reducing agent and then with acid. Use of reducing agent prior to the use of acid results in surprisingly unexpected improved cleaning as compared to simultaneous treatment with reducing agent and acid.

Abstract: A method for recovering the activity of a ruthenium catalyst which comprises a step of bringing a ruthenium catalyst decreased in activity by its use in hydrogenation of an unsaturated organic compound into contact with oxygen in a liquid phase, and a step of maintaining the catalyst at a hydrogen partial pressure lower than that at the hydrogenation and a temperature not lower than a temperature lower by 50.degree. C. than the hydrogenation temperature.

Abstract: Partially deactivated catalyst in a slurry hydrocarbon synthesis process is rejuvenated employing a cyclic rejuvenation process in which syngas or CO flow into the slurry is stopped to stop the hydrocarbon synthesis reaction, the CO purged out of the slurry with a purge gas in the presence of hydrogen, the catalyst rejuvenated with a hydrogen containing rejuvenating gas and the hydrocarbon synthesis reaction restarted by passing the synthesis gas feed back into the reactor. All or a portion of the purge gas and/or the rejuvenating gas may be recycled during the respective purge and/or rejuvenation. The hydrogen required during the purge is typically part of the purge gas.

Abstract: Propylene is converted to propylene oxide in a highly efficient liquid phase process wherein temperature and pressure are both increased over the course of the epoxidation, which is preferably conducted in a continuous mode of operation. The catalyst used is a heterogeneous catalyst such as titanium silicalite or titania-on-silica. The oxidizing agent is an active oxygen species such as hydrogen peroxide or an organic hydroperoxide. When the desired yield of propylene oxide can no longer be maintained, the catalyst is replaced or regenerated. Regeneration by washing the catalyst with a hot solvent containing a source of ammonium or alkali metal cations is highly effective, especially where the catalyst is a titanium-containing zeolite.

Abstract: The present invention relates to a biological process for regenerating metal-containing sulfide mitigation catalysts that are commonly known in the natural gas processing industry as liquid redox catalysts. The invention further relates to a sulfide mitigation process wherein mitigation and regeneration are performed in a single reactor under substantially anaerobic conditions. The present invention also relates to a self regenerating catalyst composition for the mitigation of sulfides.

Abstract: The present invention discloses aqueous methods for enhancing the acid sites of fluid catalytic cracking (FCC) catalysts. The methods comprise the steps of contacting an FCC catalyst, either spent or fresh, with an aqueous solution comprising water, an inorganic acid substantially free of chloride and aluminum. The acid is preferably sulfurous or sulfuric acid. The aluminum is provided by an aluminum source selected from the group consisting of the alumina trihydrates and aluminum oxide. Chloride contamination of the aluminum source should be minimal, preferably less than about 1000 ppm chloride, more preferably less than about 200 ppm chloride. The pH of the aqueous solution is adjusted to about 3-12 by the addition of a sufficient quantity of ammonium hydroxide. The FCC catalyst is added to this solution, preferably with stirring, in a weight ratio of about 1 part catalyst to about 1-10 parts water to prepare an aqueous slurry.

Abstract: A process for regenerating solid treating particles contained in at least two vessels of a swing bed regeneration operation where the effluent of the regeneration operation is maintained regeneration fluid-free and at a substantially constant flowrate has been developed. The swing bed regeneration operation involves an on-line vessel treating process fluid and an off-line vessel for regeneration. At least a portion of the process fluid effluent from the vessel on-line is conducted to a displacement surge drum. The flowrate of the process fluid effluent from the displacement surge drum is controlled so that downstream units receive a substantially constant flowrate.

Abstract: A method for removing high molecular weight solid and liquid tars and oligomers from halogenated Lewis acids catalysts is disclosed. The Lewis acids incorporating such tars and oligomers are treated with an oxidizing agent such as chlorine, a halogen fluoride or mixtures thereof for a time and at a temperature sufficient to oxidize said solid tars and oligomers. The oxidation causes such tars and oligomers to form oxidation products, which can be separated from the halogenated Lewis acid.

Abstract: The present invention discloses aqueous methods for enhancing the acid sites of fluid catalytic cracking (FCC) catalysts. The methods comprise the steps of contacting an FCC catalyst, either spent or fresh, with an aqueous solution comprising water, and a source of both phosphorus and aluminum. Optionally the solution includes sulfurous or sulfuric acid. The phosphorus is provided by phosphoric acid, phosphorous acid or ammonium dihydrogen phosphate. The aluminum is provided by an aluminum source selected from the group consisting of the alumina trihydrates and aluminum oxide. Chloride contamination of the aluminum source should be minimal, preferably less than about 1000 ppm chloride, more preferably less than about 200 ppm chloride. The pH of the aqueous solution is adjusted to about 3-12 by the addition of a sufficient quantity of an aqueous ammonium solution.

Abstract: Disclosed are (1) a method for the regeneration of a denitration catalyst wherein, in order to regenerate a denitration catalyst having reduced denitration power, the catalyst is cleaned with a cleaning fluid having a hydrofluoric acid concentration of 0.3 to 3% by weight and maintained at a temperature of 20 to 80.degree. C., and (2) a method for the regeneration of a denitration catalyst which comprises the steps of cleaning a denitration catalyst having reduced denitration power under the conditions described in (1) above, drying the cleaned catalyst, and impregnating the catalyst with a catalytically active component so as to support it on the catalyst.

Abstract: A wet recycling method for impregnated active carbon used to remove radioactive organic iodide in a nuclear power plant by extracting impregnated substance and radioactive organic iodide from the used impregnated active carbon with an acetonitrile solution and reproducing active carbon to be used in preparing impregnated active carbon, the filtered extractive solution being distilled to obtain pure acetonitrile for the use purpose as an extractive solution, the impregnated substance and radioactive organic iodide extracted in a small amount of solid, thus reducing the volume of the waste impregnated active carbon greatly to decrease solid waste material and at the same time recycle materials.

Abstract: A process for recovering a solution of Co and Mn acetates and other valuable components of a waste residue of used catalyst discharged from a plant for the liquid-phase, homogeneously catalyzed oxidation of alkylaromatic compounds, to produce polycarboxylic aromatic acids. The residue is pyrolized in a reaction zone provided forming molten metal in an electric arc or molten metal furnace under conditions which convert essentially all carbon in the residue mainly to CO, hydrogen and compounds vaporized in an effluent from the reaction zone. The effluent is passed through a liquid-gas-contacting means to yield a quench or scrubber stream. The residue may also be sludge from a pond in which the residue is stored. The alloy recovered is atomized to form a powder metal which is then digested in acetic acid, and/or aqueous hydrogen bromide, and/or mixtures thereof with the quench or scrubber stream, to form the corresponding salts.

Abstract: Procedure for the regeneration of catalysts and adsorbent materials, which comprises the thermal desorption of adsorbed substances, with water in liquid condition, at high temperature or with water in supercritical condition, without oxidizing agents.

Abstract: A reversibly deactivated, particulate catalyst in a slurry hydrocarbon synthesis slurry is rejuvenated by circulating the slurry from a slurry body through (i) a gas disengaging zone to remove gas bubbles from the slurry, (ii) a catalyst rejuvenation zone in which a catalyst rejuvenating gas contacts the catalyst in the slurry to rejuvenate it and form a rejuvenated catalyst slurry and, (iii) back into the slurry body. Removing at least a portion of the gas bubbles improves the rejuvenation process.

Abstract: A reversibly deactivated hydrocarbon synthesis catalyst in a hydrocarbon synthesis slurry is rejuvenated by passing the slurry into a lift pipe external of the reactor in which it contacts a hydrogen containing rejuvenating gas. The hydrogen rejuvenates the catalyst particles in the slurry and forms a mixture of a rejuvenation offgas which may contain catalyst deactivating species and a rejuvenated catalyst slurry. This mixture is passed into a gas separating and removal vessel in which the offgas is separated and removed from the slurry, which is then returned back into the reactor or elsewhere. The rejuvenating gas also acts as a lift gas to create slurry circulation up through the lift pipe and into the gas removal vessel.

Abstract: Oil and oil additives separated from a contaminated solid particulate filter medium, preferably diatomaceous earth particles. Portions of a mixture of oil, oil additives and the filter medium are compressed into pellets that are extracted with liquid or supercritical CO.sub.2 to form a liquid solution. The solution is separated from the pellets and then heated to 20.degree.-60.degree. C. at a superatmospheric pressure to drive off CO.sub.2 gas, which is preferably recycled by compression into liquid or supercritical CO.sub.2.

Abstract: A process for passivating contaminating metal on a hydrocarbon cracking catalyst is provided. The catalyst is contacted within a hydrocarbon catalytic cracking unit with a stabilized dispersion. The dispersion comprises a fluid vehicle, a dispersion agent, and finely milled particles of one or more metals or metal compounds for passivation of metal-contaminated cracking catalysts. The dispersion is preferably produced by a process wherein an agitated media mill is loaded with comminuting media, fluid vehicle, dispersion agent and particles of a metal or metal compound for passivation of metal-contaminated cracking catalysts. The comminuting media, fluid vehicle, and particles are then agitated until the particles are reduced in size by at least 10% and have a volumetric average particle size of less than 0.5 microns.

Abstract: A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

Abstract: The present invention relates to the isolation of a palladium-based catalyst from a mixture in which it is dissolved. More specifically, the invention relates to the isolation of a palladium-based catalyst from a mixture originating from the reaction of hydroxycarbonylation of butadiene to pentenoic acids. It therefore consists of a process for the isolation of at least a portion of the palladium dissolved in a solution also containing at least 3-pentenoic acid, characterized in that the said solution is acidified and stirred with an aqueous solution of hydrochloric acid, so as to obtain two liquid phases including an aqueous phase containing at least a portion of the palladium.

Abstract: A process for increasing the activity of a zeolite-containing particulate solid containing contaminants which block the pores of the zeolite and adversely affect the activity thereof wherein the contaminated zeolitic material is slurried with a liquid containing an acid, detergent or surfactant, the slurry is agitated to liberate the pore-blocking contaminants from the zeolite pores so that they are suspended in the liquid, a portion of the liquid is withdrawn from the slurry and filtered to remove the suspended contaminants, the resulting liquid is returned to the slurry, and the treated zeolite-containing particulate solid is liquid from the solution and recovered.

Abstract: This invention discloses an integrated process of alkylation of olefins and regeneration of spent sulfuric acid. The alkylation of olefins may be replaced by nitration of toluene or by chlor-alkali process. The sulfuric acid is used as a catalyst or a absorbent, and the spent sulfuric acid is regenerated in situ and is recycled in the alkylation of olefins, nitration of toluene or chlor-alkali processes.

Abstract: A spent zeolite-containing hydrocarbon cracking catalyst is treated by regenerating it to remove carboneous deposits. A portion of the regenerated catalyst is withdrawn from the circulating catalyst inventory of a hydrocarbon processing unit and slurried with a liquid containing an activating agent to solubilize and/or dislodge contaminants which block the pores of the zeolite and adversely affect the activity of the catalyst. The slurry is agitated to dissolve or dislodge the contaminants from the zeolite pores, and the agitated slurry, without being permitted to settle, is transferred to a fluidized drying zone where the liquid and solubilized and/or dislodged contaminants are removed from the treated catalyst which has a level of cracking activity higher than that of the catalyst in the circulating catalyst inventory. The treated catalyst is then recycled to the unit and contacted with a hydrocarbon feedstock under cracking conditions.

Abstract: A method for producing a catalytic converter including a honeycomb body having flow channels with catalytically active surfaces, includes at least partially cleaning foreign materials from a honeycomb body of a catalytic converter that has been in service. Catalytically active surfaces of the catalytic converter are restored through application of a catalytically active surface coating.

Abstract: A porous gas diffusion electrode for membrane fuel cells on an ion-conducting polymer. The electrode contains a finely divided electrocatalyst which is dispersed in a proton-conducting ionomer and has a total porosity of more than 40 to less than 75%. It supplies considerably improved performance data in comparison to known electrodes. The electrode can be produced by using pore-forming materials which are dissolved during the re-protonation of the ion-conducting polymers with sulfuric acid or are decomposed by the action of temperature.

Abstract: A process for regenerating solid treating particles contained in at least two vessels of a swing bed regeneration operation where the effluent of the regeneration operation is maintained regeneration fluid-free and at a substantially constant flowrate has been developed. The swing bed regeneration operation involves at least two vessels, one of which is on-line treating process fluid, and the other is off-line for regeneration. At least a portion of the process fluid effluent from the vessel on-line is conducted to a displacement surge drum. The flowrate of the process fluid effluent from the displacement surge drum is controlled so that downstream units receive a substantially constant flowrate.

Abstract: Hydrogen containing tail gas from a hydrocarbon synthesis reactor is used as a hydrogen containing catalyst rejuvenating gas. If CO is present, the CO content, is less than 10 mole % of the gas and the H.sub.2 to CO mole ratio is greater than 3:1. At least a portion of the water and liquid hydrocarbons are removed from the tail gas, before it is used to rejuvenate the reversibly deactivated catalyst.

Abstract: The invention relates to a process for re-processing deactivated DENOX catalysts on the basis of Ti/V/Mo/W mixed oxides.

Abstract: In a catalytic process for converting synthesis gas including hydrogen and carbon monoxide to hydrocarbons and oxygenates by a slurry Fischer-Tropsch synthesis, the wax product along with dispersed catalyst is removed from the slurry and purified by removing substantially all of the catalyst prior to upgrading the wax and returning a portion to the Fischer-Tropsch reaction. Separation of the catalyst particles from the wax product is accomplished by dense gas and/or liquid extraction in which the organic compounds in the wax are dissolved and carried away from the insoluble inorganic catalyst particles that are primarily inorganic in nature. The purified catalyst free wax product can be subsequently upgraded by various methods such as hydrogenation, isomerization, hydrocracking, conversion to gasoline and other products over ZSM-5 aluminosilicate zeolite, etc.

Abstract: A process serves for recoating a deactivated catalyst coating of a catalyst for converting harmful constituents from the exhaust gas of an internal combustion engine, particularly in a motor vehicle. In this process, washcoat and/or noble metal compounds are sprayed by means of an aerosol into the catalyst. The noble metal compounds are subsequently brought into their elemental state by means of a reducing medium flowing through the catalyst, after which the washcoat applied is dried by heat treatment or calcination. In an apparatus for carrying out the process, a first line for a carrier gas and a second line for the washcoat and/or the noble metal compounds are provided. The first line is arranged at least partly in a region before the catalyst within the second line and at its ends nearest the catalyst is provided with an atomization device.

Abstract: A reversibly deactivated hydrocarbon synthesis catalyst in a hydrocarbon synthesis slurry is rejuvenated by successively passing the slurry through at least two rejuvenation stages external of the slurry reactor, each of which comprises a rejuvenation zone followed by an offgas removal zone. This is accomplished by using a lift pipe outside the reactor into which slurry from the reactor is passed and contacts a catalyst rejuvenating gas to partially rejuvenate the catalyst particles and form a rejuvenation offgas. The gas and slurry mixture are passed into a vessel in which the gas is removed from the slurry. Rejuvenation gas is bubbled into the slurry in the vessel to further rejuvenate the catalyst. A gas removing downcomer removes gas from the slurry in the vessel before it is passed back into the reactor. The rejuvenation gas also acts as a lift gas in the lift pipe.

Abstract: A reversibly deactivated, particulate catalyst in a slurry hydrocarbon synthesis slurry is rejuvenated by circulating the slurry from a slurry body through (i) a gas disengaging zone to remove gas bubbles from the slurry, (ii) a catalyst rejuvenation zone in which a catalyst rejuvenating gas contacts the catalyst in the slurry to rejuvenate it and form a rejuvenated catalyst slurry and, (iii) back into the slurry body. Removing at least a portion of the gas bubbles improves the rejuvenation process.

Abstract: Partially deactivated catalyst in a slurry hydrocarbon synthesis process is rejuvenated employing a cyclic rejuvenation process in which syngas or CO flow into the slurry is stopped to stop the hydrocarbon synthesis reaction, the CO purged out of the slurry with a purge gas in the presence of hydrogen, the catalyst rejuvenated with a hydrogen containing rejuvenating gas and the hydrocarbon synthesis reaction restarted by passing the synthesis gas feed back into the reactor. All or a portion of the purge gas and/or the rejuvenating gas may be recycled during the respective purge and/or rejuvenation. The hydrogen required during the purge is typically part of the purge gas.

Abstract: Hydrocarbon liquid products are filtered and removed from a three phase hydrocarbon synthesis slurry comprising gas bubbles and particulate catalyst solids in a hydrocarbon liquid, by circulating the slurry through a gas disengaging downcomer immersed in the slurry to a filtration zone external or internal of the reactor, and then back into the slurry in the reactor. The gas disengagement densifies the slurry which is passed across the filtration surface under high flow conditions, to reduce solids build up on the filter as filter cake. Circulation through the filtration zone occurs by gravity and hydrostatics due to slurry density differences. The downcomer may also be a gas and solids reducing downcomer.