Abstract: A method for separating CO2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO2 from gas mixtures.

Abstract: Various methods and structures of complexes and molecules are described herein related to a zinc-centered catalyst for removing carbon dioxide from atmospheric or aqueous environments. According to one embodiment, a method for creating a tris(triazolyl)pentaerythritol molecule includes contacting a pentaerythritol molecule with a propargyl halide molecule to create a trialkyne molecule, and contacting the trialkyne molecule with an azide molecule to create the tris(triazolyl)pentaerythritol molecule. In another embodiment, a method for creating a tris(imidazolyl)pentaerythritol molecule includes alkylating an imidazole 2-carbaldehyde molecule to create a monoalkylated aldehyde molecule, reducing the monoalkylated aldehyde molecule to create an alcohol molecule, converting the alcohol molecule to create an alkyl halide molecule using thionyl halide, and reacting the alkyl halide molecule with a pentaerythritol molecule to create a tris(imidazolyl)pentaerythritol molecule.

Abstract: The present invention relates to the separation of gases, and more specifically to an inventive process for the removal of carbon dioxide gas using carefully selected ionic liquid absorbents together with water in a carefully selected ratio.

Abstract: An improved process for reduction-oxidation desulphurization uses an oxidizer operating at a pressure greater than the absorber where a liquid reduction-oxidation catalyst solution contacts a sulfur-containing gas feed stream.

Abstract: The gaseous effluent to be treated is contacted in C1 with an absorbent solution selected for its property of forming two separable phases when it has absorbed an amount of acid compounds and when it is heated. The absorbent solution laden with acid compounds is then heated in E1 and E3 so as to separate two fractions in BS1: a first absorbent solution fraction depleted in acid compounds and a second absorbent solution fraction enriched in acid compounds. The second fraction is regenerated in C2 so as to release part of the acid compounds, and the first absorbent solution fraction and the regenerated absorbent solution are recycled as absorbent solution. According to the invention, an absorbent solution portion circulating in C1 is cooled in E2 in order to prevent demixing of the solution in column C1.

Abstract: Absorption medium for acid gases comprising an oligoamine (A) of the general formula (I) and a piperazine derivative (B) of the general formula (II) in which the weight ratio of oligoamine (A) to the piperazine derivative (B) is 0.2 to 25, and also process for removing acid gases from a gas stream by contacting the gas stream at a pressure of 0.05 to 10 MPa abs with an aqueous solution of said absorption medium which is brought to and maintained at a temperature of 20 to 80° C.

Abstract: A method for scavenging hydrogen sulfide from geothermal steam in a condenser under vacuum. A fine curtain of atomized acrolein-water droplets may be sprayed into geothermal steam condensers in an amount of approximately 2:1 molar ratio of acrolein to H2S based on hydrogen sulfide in the incoming steam from the turbine. The range being approximately 0.1 ppm to 500 ppm of sulfide. The acrolein is allowed to react with the gas phase H2S to form non-volatile aldehyde byproducts which partition into the water phase, are returned to the cooling tower and ultimately removed by normal cooling-tower blow down.

Abstract: The use of a dialdehyde (e.g. glyoxal) and a nitrogen-containing scavenger (e.g. a triazine) when injected separately in media containing hydrogen sulfide (H2S) and/or mercaptans to scavenge H2S and/or mercaptans therefrom gives a synergistically better reaction rate and overall scavenging efficiency, i.e. capacity, over the use of the dialdehyde or the nitrogen-containing scavenger used alone, but in the same total amount of the dialdehyde and nitrogen-containing scavenger. The media may include an aqueous phase, a gas phase, a hydrocarbon phase and mixtures of a gas and/or hydrocarbon phase with an aqueous phase.

Abstract: An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

Abstract: Solvent absorption processes for separating components of an impure feed gas are disclosed. The processes involve two stages of gas-liquid contacting, namely a first, absorption stage and a second, stripping stage. In the case of a carbon dioxide (CO2)-containing methane gas as an impure feed gas, contacting, in the stripping stage, the solvent effluent from the absorption stage with a recycled vapor fraction of the solvent effluent from the stripping stage can improve the recovery and purity of not only the methane (and/or other light hydrocarbons in the impure feed gas), but also that of the CO2 contaminant gas.

Abstract: Disclosed is a formulation for the absorption of CO2, which comprises water, at least one CO2 absorption compound and a carbonic anhydrase as an activator to enhance the absorption capacity of the CO2 absorption compound. The invention also concerns the use of carbonic anhydrase, in a CO2 absorption solution to increase the CO2 absorption rate of such solution.

Abstract: An absorption medium for removing acid gases from a fluid stream comprises an aqueous solution of a) of at least one metal salt of an aminocarboxylic acid, and b) of at least one acid promoter, wherein the molar ratio of b) to a) is in the range from 0.0005 to 1.0. The acid promoter is selected from mineral acids, carboxylic acids, sulfonic acids, organic phosphonic acids and partial esters thereof. The absorption medium, compared with absorption media based on amino acid salts, has a reduced regeneration energy requirement without significantly reducing the absorption capacity of the solution for acid gases. In a process for removing acid gases from the fluid stream, the fluid stream is brought into contact with the absorption medium.

Abstract: A process for the reduction of carbon dioxide (or CO2) from various types of gas emitting sources containing carbon dioxide, including the reduction of carbon dioxide from industrial gas emitting sources via the use of an ion exchange material in which a heated stream of carbon dioxide is utilized in the regeneration of the ion exchange material.

Abstract: Disclosed is a process for removing organic sulfur from more than one reactive fuel gas stream. A reactor vessel that is provided with at least one bed of hydrodesulfurization catalyst is used to hydrodesulfurize multiple reactive fuel gas streams with a less reactive fuel gas stream being introduced into the reactor vessel at a point above the introduction point of a more reactive fuel gas stream. An hydrotreated fuel gas is yielded from the reactor vessel having a hydrogen sulfide concentration and a low organic sulfur content.

Abstract: Methods, systems, apparatuses and compositions for extracting selected gases from a gas stream are provided. In some embodiments the invention involve a process of bringing a gas stream in contact with a primary sorbent, releasing a selected gas from the primary sorbent to create a selected gas-enriched gas mixture, and bringing the selected gas-enriched gas mixture in contact with an aqueous solution. The aqueous solution absorbs the selected gas from the selected gas-enriched gas mixture. In some embodiments, the selected gas is carbon dioxide.

Abstract: An absorption medium for the removal of acid gases from a fluid stream comprises an aqueous solution a) of at least one amine and b) at least one phosphonic acid, wherein the molar ratio of b) to a) is in the range from 0.0005 to 1.0. The phosphonic acid is, e.g., 1-hydroxyethane-1,1-diphosphonic acid. The absorption medium exhibits a reduced regeneration energy requirement compared with absorption media based on amines or amine/promoter combinations, without significantly decreasing the absorption capacity of the solution for acid gases.

Abstract: Disclosed is a formulation for the absorption of CO2, which comprises water, at least one CO2 absorption compound and a carbonic anhydrase as an activator to enhance the absorption capacity of the CO2 absorption compound. The invention also concerns the use of carbonic anhydrase, in a CO2 absorption solution to increase the CO2 absorption rate of such solution.

Abstract: A process for the clean-up of a crude syngas stream having widely varying composition and particulate load. The process includes quenching the crude syngas stream with a liquid stream to cool the syngas stream and remove particulates, tars and heavier hydrocarbon compounds. The process further includes co-scrubbing the syngas stream to remove both HCl and NH3 from the syngas stream, removing particulate matter from the syngas stream, and removing sulfur from the syngas stream. A syngas treatment system is also disclosed.

Abstract: According to an exemplary aspect of the invention a method of sorption of CO2 out of flue gas is provided, wherein the method comprises contacting the flue gas and an ionic liquid comprising an anion and a non-aromatic cation.

Abstract: Ionic liquids containing a cation with a potentially nucleophilic carbon atom bearing a relatively acidic hydrogen atom bonded to a potentially nucleophilic carbon atom, typically in the conjugated —NC(H)N— structure or a —NC(H)S— structure of imidazolium, imidazolidinium or thiazolium salts, can be capable of acting as sorbents for CO2 in cyclic separation processes. The ionic liquid may be used on its own, mixed with a solvent, preferably an aprotic, polar, non-aqueous solvent such as toluene, DMSO, NMP or sulfolane, or in conjunction with a non-nucleophilic nitrogenous base promoter compound having a pKa of at least 10.0 such as a carboxamidine or a guanidine.

Abstract: In some embodiments, the invention provides systems and methods for removing carbon dioxide and/or additional components of waste gas streams, comprising contacting the waste gas stream with an aqueous solution, removing carbon dioxide and/or additional components from the waste gas stream, and containing the carbon dioxide and/or additional components, in one form or another, in a composition. In some embodiments, the composition is a precipitation material comprising carbonates, bicarbonates, or carbonates and bicarbonates. In some embodiments, the composition further comprises carbonate and/or bicarbonate co-products resulting from co-processing SOx, NOx, particulate matter, and/or certain metals. Additional waste streams such as liquid, solid, or multiphasic waste streams may be processed as well.

Abstract: A gas separation process for treating off-gas streams from reaction processes, and reaction processes including such gas separation. The invention involves flowing the off-gas across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, and passing the permeate/sweep gas mixture to the reaction. The process recovers unreacted feedstock that would otherwise be lost in the waste gases in an energy efficient manner.

Abstract: The present invention relates to a method for capturing carbon oxides, in particular for recovering carbon oxides from an industrial facility, and specifically to a method for capturing CO2 contained in a gas flow with a view to storing said CO2, said method including placing said gas flow in contact with a solvent including an organometallic compound, such that said solvent captures said carbon oxides to form an enriched solvent. The present invention relates in particular to the use of said capture method in post-combustion or pre-combustion processes.

Abstract: Hydrogen sulfide (H2S) and/or mercaptan scavengers are chemicals that remove H2S and/or mercaptans from gas, oil and water. Water-based formulations may be made and used employing scavenging compounds having the formulae: wherein each R1, R2, R3, and R4 are the same or different and are selected from the group consisting of hydrogen, an alkyl, an alkenyl, an aryl, an acyl, a halogen, a hydroxyl, a nitro, an alkyl ester, an aryl ester, an alkyl ether, an aryl ether, a hydroxymethyl, an anhydride group, an amino, and a sulfide. In one non-limiting embodiment the compounds (A) and (B) do not contain nitrogen atoms. Water-based formulations, such as those using a protic solvent with the above compounds, work well as H2S scavengers.

Abstract: The invention relates to a method for reducing the CO2 content of a gas by contacting the gaseous effluent to be treated with an absorbent that contains a CO2 trapping agent in the impregnated state on a substrate made of a solid composite material (M) containing a polymer (P) and a compound (C) selected from mineral oxides, silico-aluminates, and activated carbon, wherein said material (M) has an average particle size (D50) higher than or equal to 100 ?m, and a pore space (Vd1) defined by pores having a diameter of between 3.6 and 1000 nm and which is at least 0.2 cm3/g. The invention also relates to specific absorbents used in said method.

Abstract: Various methods and structures of complexes and molecules are described herein related to a zinc-centered catalyst for removing carbon dioxide from atmospheric or aqueous environments. According to one embodiment, a method for creating a tris(triazolyl)pentaerythritol molecule includes contacting a pentaerythritol molecule with a propargyl halide molecule to create a trialkyne molecule, and contacting the trialkyne molecule with an azide molecule to create the tris(triazolyl)pentaerythritol molecule. In another embodiment, a method for creating a tris(imidazolyl)pentaerythritol molecule includes alkylating an imidazole 2-carbaldehyde molecule to create a monoalkylated aldehyde molecule, reducing the monoalkylated aldehyde molecule to create an alcohol molecule, converting the alcohol molecule to create an alkyl halide molecule using thionyl halide, and reacting the alkyl halide molecule with a pentaerythritol molecule to create a tris(imidazolyl)pentaerythritol molecule.

Abstract: The present invention relates to a method of enriching a gaseous effluent in acid compounds, which comprises the following stages: feeding into a contactor a feed gas comprising acid compounds and a composition comprising at least two liquid phases non-miscible with one another, including an aqueous phase, at least one amphiphilic compound and at least one mixture of promoters, establishing in said contactor predetermined pressure and temperature conditions for the formation of hydrates consisting of water, promoters and acid compounds, carrying the hydrates dispersed in the phase non-miscible in the aqueous phase through pumping to a hydrate dissociation drum, establishing in the drum the hydrate dissociation conditions, discharging the gas resulting from the dissociation enriched in acid compounds in relation to the feed gas.

Abstract: A method and apparatus are provided for absorbing acid gases from a synthesis gas prior to combustion. In one embodiment, a vessel is provided for receiving a synthesis gas and a physical solvent. The vessel includes one or more membrane contactors that provide an interface for physical absorption of one or more acid gases from the synthesis gas into the physical solvent.

Abstract: This invention relates to a method and plant for energy-efficient removal of CO2 from a gas phase by means of absorption. The invention is particularly suitable for use in connection with thermal power plants fired by fossil fuels, and is also well-suited for retrofitting in existing thermal power plants. A processing plant according to the invention comprises three sections: a primary CO2-generating process that serves as main product supplier; a CO2-capture and separation plant based on absorption and desorption of CO2 respectively by/from at least one absorbent; and a second CO2-generating process where combustion of carbonaceous fuel in pure oxygen atmosphere serves as energy supply to at least a part of the thermal energy necessary to drive the regeneration of the absorbent in the desorption column(s).

Abstract: In accordance with one aspect, the present invention provides an amino-siloxane composition comprising at least one of structures I, II, III, IV or V said compositions being useful for the capture of carbon dioxide from gas streams such as power plant flue gases. In addition, the present invention provides methods of preparing the amino-siloxane compositions are provided. Also provided are methods for reducing the amount of carbon dioxide in a process stream employing the amino-siloxane compositions of the invention as species which react with carbon dioxide to form an adduct with carbon dioxide. The reaction of the amino-siloxane compositions provided by the present invention with carbon dioxide is reversible and thus, the method provides for multicycle use of said compositions.

Abstract: A method for scavenging hydrogen sulfide from geothermal steam in a condenser under vacuum. A fine curtain of atomized acrolein-water droplets may be sprayed into geothermal steam condensers in an amount of approximately 2:1 molar ratio of acrolein to H2S based on hydrogen sulfide in the incoming steam from the turbine. The range being approximately 0.1 ppm to 500 ppm of sulfide. The acrolein is allowed to react with the gas phase H2S to form non-volatile aldehyde byproducts which partition into the water phase, are returned to the cooling tower and ultimately removed by normal cooling-tower blow down.

Abstract: In some embodiments, the invention provides systems and methods for removing carbon dioxide and/or additional components of waste gas streams, comprising contacting the waste gas stream with an aqueous solution, removing carbon dioxide and/or additional components from the waste gas stream, and containing the carbon dioxide and/or additional components, in one form or another, in a composition. In some embodiments, the composition is a precipitation material comprising carbonates, bicarbonates, or carbonates and bicarbonates. In some embodiments, the composition further comprises carbonate and/or bicarbonate co-products resulting from co-processing SOx, NOx, particulate matter, and/or certain metals. Additional waste streams such as liquid, solid, or multiphasic waste streams may be processed as well.

Abstract: The present invention relates to nanocomposite materials comprising: graphite-based material dispersed among transition metal-organic framework (MOF) units, wherein the graphite-based material is chemically linked to MOF units; wherein the graphite-based material is present in the range of about 5 wt. % to about 60 wt. % of the composite material.

Abstract: The invention relates to a method for removing hydrogen sulphide and other acidic gas components from pressurized technical gases by means of a physical detergent and for obtaining sulphur from hydrogen sulphide by using a Claus system. The hydrogen sulphide and the other acidic gas components are removed in an absorbent manner from the physical detergent, the physical detergent undergoes multi-step regeneration, said multi-step regeneration comprising at least one device for CO enrichment, a device for H2S enrichment, a device for CO2 stripping and a device for thermal regeneration. The various regeneration steps consist of various pressure steps and have a lower pressure than that of the absorption. A hydrogen sulphide rich Claus gas is withdrawn from one of the regeneration steps and is guided to a Claus system where sulphur is produced. The residual gas exiting from the Claus system is hydrated and is condensed under pressure, corresponding to one of the regeneration steps.

Abstract: The present invention is based on the realization that the carbon dioxide component of industrial gas streams also containing steam can be processed so to utilize either as latent and/or sensible heat the heat available from the steam component to assist in separating carbon dioxide from the remainder of the gas stream. For example, flue gases produced by power stations burning brown coal, black coal or natural gas inherently contain a useful amount of energy that can be harnessed according to the present invention. According to particular preferred forms of the invention, nitrogen and sulphur constituent such as SOx and NOx, H2S and other nitrogen containing compounds may also be removed from the gas stream through direct contact with the absorbing medium and used to produce by-products such as fertiliser material.

Abstract: A process for producing a purified synthesis gas stream from a contaminated feed synthesis gas stream is disclosed. A part of the feed synthesis gas stream is subjected to a water gas shift step. The water gas shift step is used in combination with bulk contaminant removal followed by polishing to thereby remove the contaminants from the synthesis gas stream so as to provide the purified synthesis gas stream having a desired low level of contaminants.

Abstract: Systems and methods of capturing and sequestering carbon dioxide, comprising mixing a substantially non-aqueous solvent and an alkali such that the solvent and alkali form a solvent suspension, mixing water and a flue gas containing carbon dioxide with the solvent suspension such that a reaction occurs, the reaction resulting in the formation of a carbonate, water and heat.

Abstract: Compositions and associated methods directed to the removal of sulfurous compounds from air are presented herein. The compositions and methods may be able to treat air with H2S concentrations of at least 1000 ppm. The compositions and associated methods are used to remove sulfurous compounds from air associated with wastewater systems in various aspects.

Abstract: Apparatus comprising an absorber device provided with a plurality of sequentially adjacent sections for flowing a gas stream therethrough. A solvent reactable with components of the gas stream is ingressed into and egressed from each section of the absorber device by a conduit infrastructure. The conduit infrastructure has a plurality of heat exchange and cooling equipment, and communicates with solvent recovery and regeneration equipment. A process wherein a liquid solvent selected for reacting with gaseous components, is counter-flowed against the gas stream. The liquid solvent temperature is controllably manipulated between each section of the absorber device to provide: (a) thermodynamic-driven mass transfer at the front end of the absorber device, and (b) kinetic-driven mass transfer at the back end of the absorber device. Heat generated during recovery of gaseous components from the liquid solvent is recovered for use in regenerating the solvent system.

Abstract: A reforming method of a metallurgical furnace generated exhaust gas includes reforming a high temperature exhaust gas discharged from a metallurgical furnace by adding a reducing agent to the gas, wherein addition of the reducing agent is initiated when an oxygen concentration in the exhaust gas is 1 vol % or less, and a reforming reaction is completed when a temperature of the exhaust gas is 800° C. or higher, and an apparatus thereof. The reducing agent is blown from a reducing agent blowing nozzle having a double pipe structure.

Abstract: An process for efficiently deacidizing a gaseous mixture is described. The process utilizes a self-concentrating absorbent that absorbs an acid gas at reduced overall energy costs for the deacidizing operation.

Abstract: The invention relates to a method for recovering absorbed hydrocarbon components while absorbing acid gases from technical gases, as for example a natural gas, by means of physically active absorption agents, wherein the inventive method consists in increasing the pressure of a loaded absorption agent extracted from an adsorption device, in adding said loaded absorption agent to the top of a rectification column which consist of a lower feeding stove and of one or several lateral stoves operating at a pressure slightly greater than the absorption column pressure, in adjusting an equilibrium is said rectification column in such a way that the acid gas concentration in the absorbent agent increases in the direction away from the bottom of the column and the hydrocarbon concentration decreases in said direction, in extracting a heated hydrocarbon-poor and acid gas component-rich absorption agent from the bottom of the column and in transferring said agent to an acid gas desorption device, in extracting a hydroca

Abstract: A method of generating hydrogen-enriched fuel gas and carbon dioxide comprising converting hydrocarbon molecules from a gaseous hydrocarbon feed stream into hydrogen and carbon dioxide, separating the hydrogen and carbon dioxide, blending the hydrogen back into the gaseous hydrocarbon feed stream to generate a hydrogen-enriched fuel gas, and utilizing the carbon dioxide for storage or sequestration. A system for generating hydrogen-enriched fuel gas and carbon dioxide comprising an inlet handling system, a syngas and water-gas shift system, a water-gas compression system, a carbon dioxide recovery system, a dehydration system, and a carbon dioxide compression system.

Abstract: A method for treating a fluid to be scrubbed, comprising filling a scrubber with a volume of biodiesel or biomass adequate to cover a sintered permeable membrane in the reaction chamber and a bit more to create a reaction zone in not only a plurality of pores in the membrane with fluid but in a reaction zone above the membrane, then introducing fluid to be scrubbed to the membrane, building up pressure in the reaction chamber, and passing a scrubbed fluid from the reaction zone to an exit port at a rate equal to the rate the fluid to be scrubbed is introduced.

Abstract: A process for maintaining a low carbon monoxide content in a carbon dioxide product that is made in a synthesis gas purification process is disclosed. More particularly, the invention involves an improved process in which a portion of a loaded solvent is sent through a carbon dioxide absorber instead of to a series of carbon dioxide flash drums.

Abstract: In some embodiments, the invention provides systems and methods for removing carbon dioxide and/or additional components of waste gas streams, comprising contacting the waste gas stream with an aqueous solution, removing carbon dioxide and/or additional components from the waste gas stream, and containing the carbon dioxide and/or additional components, in one form or another, in a composition. In some embodiments, the composition is a precipitation material comprising carbonates, bicarbonates, or carbonates and bicarbonates. In some embodiments, the composition further comprises carbonate and/or bicarbonate co-products resulting from co-processing SOx, NOx, particulate matter, and/or certain metals. Additional waste streams such as liquid, solid, or multiphasic waste streams may be processed as well.

Abstract: Systems and processes utilize one or more methods of providing overhead waste process heat to increase the feed temperature of the hot solvent stripping regeneration loop in an acid gas removal process. A heated rich solvent stream can be the primary feed for the hot solvent stripping regeneration loop, and one or more slip streams can be heated and then combined with the heated rich solvent stream to form a combined rich solvent stream prior to further processing in downstream units to remove acid gas from the solvent. A first slip stream can be heated in a stripper gas heat exchanger by heat exchange with a stripped gas stream. A second slip stream can be heated in a regenerator exchanger by heat exchange with an acid gas stream. A third slip stream can be heated in a recycle gas exchanger by heat exchange with a compressed recycle gas stream.

Abstract: Disclosed is a process for removing sulfur from a fuel gas stream that comprises an organic sulfur compound and a light olefin. The process includes introducing a fuel gas stream into an elongated hydrotreating reactor vessel in which it is contacted with a hydrodesulfurization catalyst under hydrodesulfurization process conditions. A quench gas stream is also introduced into the elongated hydrotreating reactor vessel at a location below the point of introduction of the fuel gas stream. A reactor effluent is yielded that contains hydrogen sulfide and a significantly reduced organic sulfur concentration that is below the organic sulfur concentration of the fuel gas stream.

Abstract: A process for the removal of an amine capturable gas from a feed gas stream using an amine solvent, the process comprises (a) contacting the feed gas stream with a lean amine solvent to form a rich amine solvent, wherein heat stable salts are present in the rich amine solvent; (b) stripping amine capturable gas from the rich amine solvent to form the lean amine solvent and an overhead reflux stream; (c) periodically contacting at least a portion of one or both of the lean amine solvent and the rich amine solvent with an anion exchange resin to form a first heat stable salt lean amine solvent; (d) periodically regenerating the anion exchange resin, wherein during the regeneration of the anion exchange resin, at least a portion of the reflux stream is used to wash the amine solvent from the anion exchange resin to produce a second heat stable salt lean amine solvent; and, (e) recycling at least a portion of the first and the second heat stable salt lean amine solvent for use in capturing the amine capturable ga

Abstract: The present invention provides a method for binding gaseous molecules, the method comprising contacting gases comprising the gaseous molecules with trivalent metal complexes. Typically, the gaseous molecules comprise polar molecules of greenhouse gases, especially the oxides of carbon, nitrogen and sulphur. Preferably, the trivalent metal complexes comprise complexes of actinide metals, most preferably uranium. The method is particularly useful in the removal of so-called greenhouse gases from the atmosphere, and is therefore of potentially very great value environmentally. The invention also provides trivalent metal complexes comprising sandwich complexes of trivalent metals selected from transition metals and actinide metals, the complexes comprising two ligands selected from pentalenyl, indenyl, cyclopentadienyl and cyclooctatetraene ligands. The invention further provides a method for the preparation of the trivalent metal complexes.