Abstract: A method of screening catalysts for liquid-phase selective hydrogenation by preparing a test catalyst by adding a promoter to a reference catalyst; preparing a liquid reactant stream comprising C2H2 dissolved in n-methyl-2-pyrrolidone; testing the test and reference catalysts by contacting the reactant stream and gas mixture comprising hydrogen and carbon monoxide in continuous flow with the test catalyst and reference catalyst, respectively, at selective hydrogenation reaction conditions to produce a product stream, condensing substantially all of the n-methyl-2-pyrrolidone from the product stream; measuring the concentrations of products comprising C2H2, C2H4, and C2H6 in the product stream at steady state; determining performance parameters for the test catalyst and the reference catalyst comprising the respective C2H2 conversion Sc and C2H4 selectivity relative to C2H6 Ss; and comparing the test catalyst performance parameters to those for the reference catalyst.

Abstract: The present invention relates to a process for restoring the activity of spent catalysts for the hydrogenation of aromatic nitro compounds, in which a regeneration comprising at least a first burning off stage, a first washing stage, a second burning off stage and a second washing stage is carried out at periodic intervals.

Abstract: The present invention relates to a multifunctional catalyst additive composition for reduction of carbon monoxide and nitrogen oxides in a fluid catalytic cracking process comprising an inorganic oxide; alumino silicate or a zeolite; a noble metal; a metal of Group I A; a metal of Group II A; a metal of Group III A; a metal of Group IV A; a metal of Group V A; a rare earth oxide; at least a metal of Group VIII. The composition is attrition resistant and is incorporated on a support. The present invention also discloses a process for preparing the multifunctional catalyst additive composition. The present invention also discloses a fluid cracking catalyst comprising the multifunctional catalyst additive composition.

Abstract: Solvent extraction is used to remove wax and contaminants from an iron-based Fischer-Tropsch catalyst in a natural circulation continuous-flow system. The wax-free catalyst is then subjected to controlled oxidation to convert the iron to its initial oxidized state, Fe2O3. Reactivation of the oxide catalyst precursor is carried out by addition of synthesis gas.

Abstract: One exemplary embodiment can be an apparatus for treating a hydrocarbon stream having one or more compounds with a boiling point of about 140° to about 450° C. The apparatus can include an extraction zone and a regeneration zone. The extraction zone can include at least one settler. Each settler can have a height and a length. Typically the length is greater than the height. Also, the settler can form a boot, which can be adapted to receive a feed at one end. The regeneration zone may include a regenerator for an ionic liquid. The regenerator can include a column adapted to provide a regenerated ionic liquid to the extraction zone.

Abstract: A homogenous process for the hydrogenation of the carboxylic acids and/or derivatives thereof in the presence of a catalyst comprising ruthenium, rhodium, iron, osmium or palladium, and an organic phosphine is described in which the hydrogenation is carried out in the presence of at least about 1% by weight water. A process for regenerating a catalyst comprising ruthenium, rhodium, iron, osmium or palladium and an organic phosphine is also described in which the regeneration is carried out in the presence of hydrogen and water.

Abstract: A process is provided for producing a complex oxide catalyst which exhibits superior catalytic activity in a vapor phase catalytic oxidation reaction, particularly in production of unsaturated aldehyde and unsaturated carboxylic acid. The process is characterized by the steps of preparing an aqueous slurry by mixing a complex oxide containing molybdenum and cobalt with an acid and water; drying the aqueous slurry; and calcining the resulting dried solid. Preferably, the complex oxide is obtained as follows: a molybdenum- and cobalt-containing complex oxide catalyst which has been used in a vapor phase catalytic oxidation reaction is mixed with an aqueous extracting solution obtained by dissolving at least one of ammonia and an organic base in water, to thereby extract molybdenum and cobalt into the aqueous phase; and the aqueous phase is dried and is then calcined under an atmosphere of an oxidizing gas.

Abstract: The present invention relates to an improved preparation method of an organic-transition metal hydride as a hydrogen storage material, especially an improved preparation method of an organic-transition metal hydride containing aryl or alkyl group that facilitates safe and reversible storage of a massive amount of hydrogen. The present invention also relates to a preparation method of an organic-transition metal hydride comprising the steps of: preparing a complex reducing agent composition by reacting alkali metal, alkali earth metal or a mixture thereof and a C10 to C20 aromatic compound in aprotic polar solvent; and preparing the organic-transition metal hydride by reacting the prepared complex reducing agent composition with an organic-transition metal halide in the absence of a hydrogen source.

Abstract: Processes described include reacting a fresh or spent catalyst, or sorbent, with a solution containing an extracting agent (such as an acid or a base). Preferably, the catalyst contains both alumina and a molecular sieve (or a sorbent), and the reaction is performed under relatively mild conditions such that the majority of the base material does not dissolve into the solution. Thus, the catalyst can be re-used, and in certain instances the catalyst performance even improves, with or without re-incorporating certain of the metals back into the catalyst. Additionally, metals contained in the catalyst, such as Na, Mg, Al, P, S, Cl, K, Ca, V, Fe, Ni, Cu, Zn, Sr, Zn Sb, Ba, La, Ce, Pr, Nd, Pb, or their equivalent oxides, can be removed from the catalyst. Some of the metals that are removed are relatively valuable (such as the rare earth elements of La, Ce, Pr and Nd).

Abstract: Provided is a method for cleaning a used denitration catalyst, which prevents release of mercury to the atmosphere by collecting and removing mercury which would have been released to the atmosphere in the process of cleaning the used denitration catalyst. The method comprises immersing the used denitration catalyst mainly composed of titanium oxide and having been used in exhaust gas containing mercury in a cleaning liquid, and stirring the cleaning liquid to dissolve and remove catalyst poisons including the mercury from the used denitration catalyst, wherein a waste gas generated in the step of stirring the cleaning liquid is conducted to a flue having a mercury removal device so as to remove the mercury, and then vented to the atmosphere.

Abstract: A system using electrochemically-activated water (ECAW) for manufacturing, processing, packaging, and dispensing beverages including: (a) using ECAW to neutralize incompatible residues when transitioning from the production of one beverage to another; (b) using ECAW to rehabilitate and disinfect granular activated charcoal beds used in the feed water purification system; (c) producing a carbonated ECAW product and using the carbonated ECAW for system cleaning or disinfecting; (d) using ECAW solutions in the beverage facility clean-in-place system to achieve improved microbial control while greatly reducing water usage and reducing or eliminating the use of chemical detergents and disinfectants; (e) further reducing biofilm growth in the processing system, and purifying ingredient water without the use of chlorine, by adding an ECAW anolyte to the water ingredient feed stream; and/or (f) washing the beverage product bottles or other packages with one or more ECAW solutions prior to packaging.

Abstract: A method of constructing a phosphorous adsorbing structure includes creating a design model that indicates a percentage of phosphorous removed from a water supply per an amount of a predetermined adsorbent exposed to the water supply based upon an original concentration of phosphorous in the water supply and a retention time of water in the adsorbing structure.

Abstract: The invention provides a process for the off site regeneration of a solid catalyst, comprising two consecutive steps: a first step of washing the catalyst using one or more fluid(s) in the supercritical state, so as to extract from the catalyst at least a portion of the hydrocarbons present at the surface of the latter, followed by a second step of combustion of at least a portion of the coke present at the surface of the said catalyst by a heat treatment of the latter in the presence of oxygen and at a temperature ranging from 300° C. to 600° C.

Abstract: Processes described include reacting a fresh or spent catalyst, or sorbent, with a solution containing an extracting agent (such as an acid or a base). Preferably, the catalyst contains both alumina and a molecular sieve (or a sorbent), and the reaction is performed under relatively mild conditions such that the majority of the base material does not dissolve into the solution. Thus, the catalyst can be re-used, and in certain instances the catalyst performance even improves, with or without re-incorporating certain of the metals back into the catalyst. Additionally, metals contained in the catalyst, such as Na, Mg, Al, P, S, Cl, K, Ca, V, Fe, Ni, Cu, Zn, Sr, Zn Sb, Ba, La, Ce, Pr, Nd, Pb, or their equivalent oxides, can be removed from the catalyst. Some of the metals that are removed are relatively valuable (such as the rare earth elements of La, Ce, Pr and Nd).

Abstract: A method for treating a catalyst base that comprises a contact area of porous material. A fluid, such as a flue gas stream, can be conducted along the contact area. A catalytically relevant substance is introduced into pores of the catalyst base using a transport fluid and remains on pore wall areas after removal of the transport fluid. The introduction is carried out such that an amount of the catalytically relevant substance relative to the surface remains on the pore wall areas as a function of location within the pore and decreases within the pore after exceeding a specific pore depth. A blocking fluid can first be introduced into pore regions beyond the specific pore depth, thus blocking these regions when transport fluid containing the catalytically relevant substance is introduced.

Abstract: Processes described include reacting a fresh or spent catalyst, or sorbent, with a solution containing an extracting agent (such as an acid or a base). Preferably, the catalyst contains both alumina and a molecular sieve (or a sorbent), and the reaction is performed under relatively mild conditions such that the majority of the base material does not dissolve into the solution. Thus, the catalyst can be re-used, and in certain instances the performance of the catalyst even improves, with or without re-incorporating certain of the metals back into the catalyst. Additionally, metals contained in the catalyst, such as Na, Mg, Al, P, S, Cl, K, Ca, V, Fe, Ni, Cu, Zn, Sr, Zn Sb, Ba, La, Ce, Pr, Nd, Pb, or their equivalent oxides, can be removed from the catalyst. Some of the metals that are removed are relatively valuable (such as the rare earth elements of La, Ce, Pr and Nd).

Abstract: The present invention relates to a process for producing a continuous flow of hydrogen by catalyzed hydrolysis of a complex hydride, which comprises at least adding continuously and at constant rate a fuel solution to a reactor comprising a complex hydride stabilized on a hydroxide on a cobalt boride catalyst that is added in excess inside said reactor. Sodium borohydride is preferably used, the hydroxide is sodium hydroxide and the catalyst is supported on nickel foam. Parameters and optimal conditions to achieve continuous production of hydrogen have been determined, which is essential in the operation of fuel cells. A facility comprising a semi continuous reactor designed to perform the above process, which needs no refrigeration is also an object of the present invention, as well as a washing and reactivation process of a catalyst of the type used in the process mentioned above.

Abstract: Processes and systems for recovering promoter-containing compounds, for example, perrhenates, from promoter-containing catalyst substrates, for example, substrates containing precious metals, such as silver, are disclosed. The processes include contacting the substrates with a first solution adapted to remove at least some of the catalyst promoter from the substrates, for example, an oxidizing agent, to produce a second solution containing catalyst promoter, passing the second solution through a porous medium adapted to capture at least some of the catalyst promoter, for example, a ion exchange resin; and passing a third solution, for example, a base solution, through the porous medium to remove at least some of the catalyst promoter from the porous medium and produce a fourth solution containing compounds having a catalyst promoter. Systems adapted to practice these processes are also disclosed.

Abstract: A method and apparatus is provided for regenerating a sorbent that has been poisoned by components derived from flue gas. The sorbent is treated with an agent to remove the poisoning components and introduce a promoting agent into the sorbent. The method and apparatus can also be used to enhance the effectiveness of a new sorbent.

Abstract: The process relates improving the recovery of a metal catalyst from an oxidizer purge stream produced in the synthesis of carboxylic acid, typically terephthalic acid, while utilizing pressure filtration.

Abstract: A method for treating a catalyst base that comprises a contact area of porous material. A fluid, such as a flue gas stream, can be conducted along the contact area. A catalytically relevant substance is introduced into pores of the catalyst base using a transport fluid and remains on pore wall areas after removal of the transport fluid. The introduction is carried out such that an amount of the catalytically relevant substance relative to the surface remains on the pore wall areas as a function of location within the pore and decreases within the pore after exceeding a specific pore depth. A blocking fluid can first be introduced into pore regions beyond the specific pore depth, thus blocking these regions when transport fluid containing the catalytically relevant substance is introduced.

Abstract: A system for effecting the pretreatment therewith of a sorbent comprising a conveying line (105), such as a pipe, and a plurality of solution nozzles operative for purposes of introducing a solution to treat the sorbent. More particularly, the conveying line (105) includes an inlet (107), an outlet (109), and an inner surface (105a) that is operative to define a passageway (190) through which sorbent particles are capable of being transported between the inlet (107) of the conveying line (105) and the outlet (109) of the conveying line (105).

Abstract: Methods for hydroprocessing of hydrocarbon feedstocks, including hydrodesulfurization and hydrodenitrogenation, using rejuvenated supported metallic catalysts are provided. The supported metallic catalysts comprised of a Group VIII metal, a Group VIB metal, are rejuvenated by a process making use of these metals, an organic complexing agent, and optionally an organic additive. The rejuvenation includes stripping and regeneration of a spent or partially spent catalyst, followed by impregnation with metals and at least one organic compound. The impregnated, regenerated catalysts are dried, calcined, and sulfided.

Abstract: The present invention refers to a method for eliminating silicon or silicon compounds that are contained in alumina based materials without destroying such alumina based materials allowing for their reutilization, its main application is being the regeneration of alumina based catalyst contaminated with silicon, which are used in hydro-treating processes in the oil industry for sulfur elimination and silicon removal from process streams. It is important to note that the procedures and/or conventional methods known so far for the elimination and removal of silicon contained in alumina based materials, use inorganic acids or their mixture in a digestion process which modifies the properties of alumina and of any other element contained in the material, thus destroying the alumina and disabling their reutilization.

Abstract: The present invention provides a process to clean water filtration media in a filtration bed. The process includes applying a granular cleaner to the water filtration media and applying an activator to the water filtration media. This causes a chemical reaction between the granular cleaner, activator and water filtration media resulting in the cleaning of the water filtration media. The residual granular cleaner and activator, along with suspended and dissolved contamination from the water filtration media, are removed by rinsing with water.

Abstract: A process to upgrade heavy oil and convert the heavy oil into lower boiling hydrocarbon products is provided. The process employs a catalyst slurry comprising catalyst particles with an average particle size ranging from 1 to 20 microns. In the upgrade process, spent slurry catalyst in heavy oil is generated as an effluent stream, which is subsequently recovered/separated from the heavy oil via membrane filtration. In one embodiment, residual hydrocarbons, i.e., heavy oil and solvent employed in the filtration for the heavy oil extraction are removed from the catalyst particles with the use of a cleaning solution comprising a sufficient amount of at least a surfactant for removing at least 90% of the hydrocarbons from the catalyst particles. In one embodiment, ultrasonic cleaning is also used for the removal of hydrocarbons. In another embodiment, a plasma source is employed for the volatilization of the hydrocarbons.

Abstract: A method to prepare an improved catalyst feed to a system to upgrade heavy oil. The method comprises: providing a spent catalyst that has been used in a hydroprocessing operation has with a solid content ranging from 5 to 50 wt. % in soluble hydrocarbons and having less than 80% but more than 10% of original catalytic activity; removing at least 50% of the soluble hydrocarbons removed in a deoiling step; treating the deoiled spent catalyst with a treating solution containing at least one of plain water, a mineral acid, an oxidizing agent, and combinations thereof to reduce the concentration of at least one metal contaminant in the deoiled spent catalyst by at least 40%. After treatment, the treated deoiled spent catalyst is slurried in a hydrocarbon medium, and fed to the heavy oil upgrade system as part of the catalyst feed system with a fresh slurry catalyst.

Abstract: A process for the regeneration of spent sulfuric acid including contacting spent sulfuric acid containing acid soluble oils (ASO) with sulfur dioxide to extract at least a portion of the ASO from the spent sulfuric acid into the sulfur dioxide. The sulfuric acid phase having a reduced ASO content and a sulfur dioxide phase containing at least a portion of the ASO may be recovered. The resulting sulfuric acid and sulfur dioxide phases may be further separated to recover ASO, sulfur dioxide, and sulfuric acid.

Abstract: The present disclosure relates to methods for treating an SCR catalyst or components of an SCR system having a decreased NOx potential efficiency as a result of particulate pluggage in the system or in one or more channels in the SCR catalyst which renders at least a portion of the catalytic active areas inaccessible for the flue gas. The methods include removal of the particulates and plug(s) using a blasting stream of a pressurized carrier gas having a particulate blasting medium directed at the SCR catalyst or component of an SCR system.

Abstract: Solvent extraction is used to remove wax and contaminants from an iron-based Fischer-Tropsch catalyst in a natural circulation continuous-flow system. The wax-free catalyst is then subjected to controlled oxidation to convert the iron to its initial oxidized state, Fe203. Reactivation of the oxide catalyst precursor is carried out by addition of synthesis gas.

Abstract: Disclosed are a system and an apparatus for regenerating an ionic liquid catalyst, which has been deactivated by conjunct polymers during any type of reaction producing conjunct polymers as a by-product, for example, isoparaffin-olefin alkylation. The system and apparatus are designed such that solvent extraction of conjunct polymers, freed from the ionic liquid catalyst through its reaction with aluminum metal, occurs as soon as the conjunct polymers de-bond from the ionic liquid catalyst.

Abstract: An ionic liquid catalyst, which has been regenerated by contacting a used ionic liquid catalyst with at least one regeneration metal in a regeneration zone in the presence of added hydrogen under regeneration conditions for a time sufficient to increase the activity of the ionic liquid catalyst. Also, an ionic liquid catalyst which has been regenerated by contacting a used ionic liquid catalyst with at least one regeneration metal in a regeneration zone in the presence of added hydrogen under regeneration conditions in the presence of an inert hydrocarbon in which conjunct polymers are soluble for a time sufficient to increase the activity of the ionic liquid catalyst.

Abstract: The present disclosure generally relates to catalytic methods for producing opioid derivatives. More particularly, the present disclosure relates to the preparation of hydrocodone, hydromorphone, or a derivative thereof, by means of a conversion or an isomerization of codeine, morphine, or a derivative thereof, respectively, using a heterogeneous ruthenium metal catalyst.

Abstract: Processes are described for the extraction and recovery of alkali metal from the char that results from catalytic gasification of a carbonaceous material. Among other steps, the processes of the invention include a hydrothermal leaching step in which a slurry of insoluble particulate comprising insoluble alkali metal compounds is treated with carbon dioxide and steam at elevated temperatures and pressures to effect the conversion of insoluble alkali metal compounds to soluble alkali metal compounds. Further, processes are described for the catalytic gasification of a carbonaceous material where a substantial portion of alkali metal is extracted and recovered from the char that results from the catalytic gasification process.

Abstract: Processes are described for the extraction and recovery of alkali metal from the char that results from catalytic gasification of a carbonaceous material. Among other steps, the processes of the invention include a hydrothermal leaching step in which a slurry of insoluble particulate comprising insoluble alkali metal compounds is treated with carbon dioxide and steam at elevated temperatures and pressures to effect the conversion of insoluble alkali metal compounds to soluble alkali metal compounds. Further, processes are described for the catalytic gasification of a carbonaceous material where a substantial portion of alkali metal is extracted and recovered from the char that results from the catalytic gasification process.

Abstract: A process for regenerating a used acidic ionic liquid catalyst, comprising: a. contacting the catalyst and hydrogen with a supported hydrogenation catalyst under hydrogenation conditions; and b. recovering a conjunct polymer that is a clear and colorless oil from the catalyst. A process for regenerating a used acidic ionic liquid catalyst which has been deactivated by conjunct polymers comprising the steps of contacting the used catalyst and hydrogen with a supported hydrogenation catalyst in a reaction zone under hydrogenation conditions in the presence of an inert hydrocarbon in which saturated conjunct polymers are soluble for a time sufficient to hydrogenate at least a portion of the conjunct polymers; and recovering the saturated conjunct polymers. Also, a process comprising: contacting the used acidic ionic liquid catalyst and hydrogen with a hydrogenation catalyst comprising a hydrogenation component under hydrogenation conditions; and recovering a conjunct polymer that is a clear and colorless oil.

Abstract: A method for separating organosulfur compounds from a liquid is provided. The method of this embodiment comprises contacting the liquid with the microporous coordination polymer to form a MCP-organosulfur inclusion compound.

Abstract: Processes and reactor systems are provided for the conversion of sugars to sugar alcohols using a hydrogenation catalyst, which includes apparatus and method for in-line regeneration of the hydrogenation catalyst to remove carbonaceous deposits.

Abstract: A method for passivating a porous ceramic article containing microcracks including filling the microcracks with a liquid, such as water, and then applying a washcoat as described herein.

Abstract: A process for regenerating a spent cobalt Fischer-Tropsch synthesis catalyst includes subjecting a spent particulate cobalt Fischer-Tropsch synthesis catalyst sequentially to a dewaxing treatment, an oxidation treatment at a pressure of 4 to 30 bar(a) and a reduction treatment, thereby regenerating the catalyst.

Abstract: The present invention provides a method of regenerating an oil adsorbent, wherein an oil adsorbent even if containing a large amount of oil can be regenerated without taking it out from the facility. The method of regenerating an oil adsorbent comprises washing a carbonaceous oil adsorbent made from calcined coke, with oil adsorbed thereon, with warm water of 40° C. or higher or gas-bubbled warm water of 40° C. or higher.

Abstract: Disclosed herein is a method of regenerating a titanium-containing molecular sieve catalyst. Particularly, this invention provides a method of regenerating a titanium-containing molecular sieve catalyst used in epoxidation of olefin through simple treatment using a mixture solvent comprising aqueous hydrogen peroxide and alcohol. According to the method of this invention, when the catalyst having decreased activity is regenerated, the activity of the regenerated catalyst is equal to that of new catalyst and can be maintained stable for a long period of time.

Abstract: A method of preparing, preferably recycling, a catalyst support material is disclosed and is particularly applicable to recycling a titania support. The invention includes crushing the used catalyst support that is obtained by leaching catalytic components from a used supported catalyst and preferably combining it with new catalyst support in order to provide the required average particle size and ratio of crystal phases. The invention has a number of benefits including making use of used catalyst support materials which have been conventionally disposed of and also providing a method to more efficiently recycle the active component. Where the support is recycled for a similar application, less promoter may be required.

Abstract: A process for regenerating a used acidic ionic liquid catalyst comprising contacting the used ionic liquid catalyst with at least one ‘regeneration’ metal in a regeneration zone in the presence of added hydrogen under regeneration conditions for a time sufficient to increase the activity of the ionic liquid catalyst is described. In one embodiment, regeneration is conducted in the presence of a hydrocarbon solvent.

Abstract: A regenerable sorbent for the removal of acid gas from a fluid stream. The regenerable sorbent is made from raw materials such as iron mineral, expansive clay and starch. Acid gas is removed from the fluid stream by a process where the raw materials are obtained, crushed, sifted, possibly pelletized, calcined and contacted with the fluid stream containing the acid gas.

Abstract: A method of regeneration of a SCR catalyst for use in high temperature thermal processes such as in a power plant facility burning fossil fuels, bio-based fuels, or a combination thereof, wherein the catalyst is poisoned by phosphorous components in the flue gas and the catalyst is treated using a base, preferably an alkali metal hydroxide.

Abstract: A process for regenerating a used acidic ionic liquid catalyst, comprising: a. contacting the catalyst and hydrogen with a supported hydrogenation catalyst under hydrogenation conditions; and b. recovering a conjunct polymer that is a clear and colorless oil from the catalyst. A process for regenerating a used acidic ionic liquid catalyst which has been deactivated by conjunct polymers comprising the steps of contacting the used catalyst and hydrogen with a supported hydrogenation catalyst in a reaction zone under hydrogenation conditions in the presence of an inert hydrocarbon in which saturated conjunct polymers are soluble for a time sufficient to hydrogenate at least a portion of the conjunct polymers; and recovering the saturated conjunct polymers. Also, a process comprising: contacting the used acidic ionic liquid catalyst and hydrogen with a hydrogenation catalyst comprising a hydrogenation component under hydrogenation conditions; and recovering a conjunct polymer that is a clear and colorless oil.

Abstract: A process for converting fine catalyst slurried in heavy oil into a coke-like material from which catalytic metals can be recovered comprises mixing fine catalyst slurried in heavy oil with solvent, which causes asphaltenes in the heavy oil to precipitate from the heavy oil; separating fine catalyst and precipitated asphaltenes from the heavy oil and solvent; and converting precipitated asphaltenes to a coke-like material by pyrolizing fine catalyst and precipitated asphaltenes separated from the heavy oil.

Abstract: A desulfurizer containing at least a composition of a highly concentrated amorphous iron oxide hydroxide as the active ingredient. A method for preparing a composition containing at least a highly concentrated amorphous iron oxide hydroxide. A method for regenerating the desulfurizer. The desulfurizer contains at least the composition of a highly concentrated amorphous iron oxide hydroxide as the active ingredient and a binder. The composition and the desulfurizer have a high sulfur capacity and can be regenerated. This saves resources and reduces environmental pollution. The method for regenerating the desulfurizer includes at least the following steps: a) mixing a solid soluble ferrous salt with a solid hydroxide, b) kneading the mixture and allowing it to react at temperatures not exceeding 90° C., c) drying in air, d) washing with water and filtering to yield a solid, and e) drying naturally or roasting the solid.

Abstract: A metathesis catalyst which is a combination including a catalyst 1 comprising a compound that contains at least one metal element selected from tungsten, molybdenum and rhenium and a catalyst 2 comprising at least one selected from magnesium oxide and calcined hydrotalcite is easily and effectively reactivated from a degraded state due to long-term repetitive cycles of reaction and regeneration at high temperature for burning off poisonous substances or cokes, to like-new condition or a desired level. An olefin production process by a metathesis reaction includes a step of performing the reactivation. A degraded metathesis catalyst is easily and effectively reactivated by being contacted with water at not more than 50° C. or water vapor at not more than 170° C.