A process for the purification of CO.sub.2 from chlorinated hydrocarbons and non-chlorinated hydrocarbons, comprising: contacting a CO.sub.2 stream with a chromium oxide catalyst, wherein the stream comprises the CO.sub.2, and impurities, wherein the impurities comprise the non-chlorinated hydrocarbons and the chlorinated hydrocarbons; forming a purified CO.sub.2 stream by interacting the impurities with the chromium oxide catalyst to form additional CO.sub.2 and chromium chloride; and regenerating the chromium oxide catalyst by contacting the chromium chloride with an oxygen containing gas stream.

A process and reactor for contacting a feed stream with a catalyst stream comprises a reaction chamber comprising two spent catalyst inlets for delivering two spent catalyst streams to the reaction chamber and at least one regenerated catalyst inlet for delivering a regenerated catalyst stream to the reaction chamber. The reaction chamber may also include a second regenerated catalyst inlet for delivering a second regenerated catalyst stream to the reaction chamber. The second spent catalyst inlet enables thorough mixing of catalyst streams.

A process and reactor for contacting a feed stream with a catalyst stream comprises a reaction chamber comprising two spent catalyst inlets for delivering two spent catalyst streams to the reaction chamber and at least one regenerated catalyst inlet for delivering a regenerated catalyst stream to the reaction chamber. The reaction chamber may also include a second regenerated catalyst inlet for delivering a second regenerated catalyst stream to the reaction chamber. The second spent catalyst inlet enables thorough mixing of catalyst streams.

Systems and methods are provided for performing hydrocarbon reforming within a reverse flow reactor environment (or another reactor environment with flows in opposing directions) while improving management of CO.sub.2 generated during operation of the reactor. The improved management of CO.sub.2 is achieved by making one or more changes to the operation of the reverse flow reactor. The changes can include using an air separation unit to provide an oxygen source with a reduced or minimized content of nitrogen and/or operating the reactor at elevated pressure during the regeneration stage. By operating the regeneration at elevated pressure, a regeneration flue gas can be generated that is enriched in CO.sub.2 at elevated pressure. The CO.sub.2-enriched stream can include primarily water as a contaminant, which can be removed by cooling while substantially maintaining the pressure of the stream. This can facilitate subsequent recovery and use of the CO.sub.2.

Systems and methods are provided for performing hydrocarbon reforming within a reverse flow reactor environment (or another reactor environment with flows in opposing directions) while improving management of CO.sub.2 generated during operation of the reactor. The improved management of CO.sub.2 is achieved by making one or more changes to the operation of the reverse flow reactor. The changes can include using an air separation unit to provide an oxygen source with a reduced or minimized content of nitrogen and/or operating the reactor at elevated pressure during the regeneration stage. By operating the regeneration at elevated pressure, a regeneration flue gas can be generated that is enriched in CO.sub.2 at elevated pressure. The CO.sub.2-enriched stream can include primarily water as a contaminant, which can be removed by cooling while substantially maintaining the pressure of the stream. This can facilitate subsequent recovery and use of the CO.sub.2.

A process includes reacting a feed stream containing ethanol and optionally acetaldehyde in a dehydration reactor in the presence of a dehydration catalyst system having a Group 4 or Group 5 metal oxide and a support. The process includes obtaining a product stream containing butadiene from the dehydration reactor. Another process includes reacting a feed stream containing ethanol and optionally acetaldehyde in a dehydration reactor in the presence of a dehydration catalyst system containing a tungsten oxide supported on a zeolite or a tantalum oxide supported on a zeolite. The process includes obtaining a product stream containing butadiene from the dehydration reactor.

A oxygen transfer agent useful for the oxidative dehydrogenation of saturated hydrocarbons includes at least one mixed oxide derived from manganese or compounds thereof, as well as a promoter, such as tungsten and/or phosphorus. The oxygen transfer agent may also include an alkali metal or compounds thereof, boron or compounds thereof, an oxide of an alkaline earth metal, and an oxide containing one or more of one or more of manganese, lithium, boron, and magnesium. A reactor is at least partially filled with the oxygen transfer agent in the form of a fixed or circulating bed and provides an unsaturated hydrocarbon product, such as ethylene and/or propylene. The oxygen transfer agent may be regenerated using oxygen.

A oxygen transfer agent useful for the oxidative dehydrogenation of saturated hydrocarbons includes at least one mixed oxide derived from manganese or compounds thereof, as well as a promoter, such as tungsten and/or phosphorus. The oxygen transfer agent may also include an alkali metal or compounds thereof, boron or compounds thereof, an oxide of an alkaline earth metal, and an oxide containing one or more of one or more of manganese, lithium, boron, and magnesium. A reactor is at least partially filled with the oxygen transfer agent in the form of a fixed or circulating bed and provides an unsaturated hydrocarbon product, such as ethylene and/or propylene. The oxygen transfer agent may be regenerated using oxygen.

The present invention relates to a process for producing butadiene from ethanol, in two reaction steps, comprising a step a) of converting ethanol into acetaldehyde and a step b) of conversion into butadiene, said step b) simultaneously implementing a reaction step and a regeneration step in (n+n/2) fixed-bed reactors, n being equal to 2 or a multiple thereof, comprising a catalyst, said regeneration step comprising four successive regeneration phases, said step b) also implementing a regeneration loop for the inert gas and at least one regeneration loop for the gas streams comprising oxygen.

Disclosed herein are methods, systems, and compositions for providing catalysts for tail gas clean up in sulfur recovery operations. Aspects of the disclosure involve obtaining catalyst that was used in a first process, which is not a tailgas treating process and then using the so-obtained catalyst in a tailgas treating process. For example, the catalyst may originally be a hydroprocessing catalyst. A beneficial aspect of the disclosed methods and systems is that the re-use of spent hydroprocessing catalyst reduces hazardous waste generation by operators from spent catalyst disposal. Ultimately, this helps reduce the environmental impact of the catalyst life cycle. The disclosed methods and systems also provide an economically attractive source of high-performance catalyst for tailgas treatment, which benefits the spent catalyst generator, the catalyst provider, and the catalyst consumer.