Systems and methods use bimetallic alloy particles for converting hydrogen sulfide (H.sub.2S) to hydrogen (H.sub.2) and sulfur (S), typically during multiple operations. In a first operation, metal alloy composite particles can be converted to a composite metal sulfide. In a second operation, composite metal sulfide from the first operation can be regenerated back to the metal alloy composite particle using an inert gas stream. Pure, or substantially pure, sulfur can also be generated during the second operation.

Systems and methods use bimetallic alloy particles for converting hydrogen sulfide (H.sub.2S) to hydrogen (H.sub.2) and sulfur (S), typically during multiple operations. In a first operation, metal alloy composite particles can be converted to a composite metal sulfide. In a second operation, composite metal sulfide from the first operation can be regenerated back to the metal alloy composite particle using an inert gas stream. Pure, or substantially pure, sulfur can also be generated during the second operation.

Systems and methods are provided for using oxycombustion to provide heat within a reverse flow reactor environment. The oxygen for the oxycombustion can be provided by oxygen stored in an oxygen storage component in the reactor. By using an oxygen storage component to provide the oxygen for combustion during the regeneration step, heat can be added to a reverse flow reactor while reducing or minimizing addition of diluents and while avoiding the need for an air separation unit. As a result, a regeneration flue gas can be formed that is substantially composed of CO.sub.2 and/or H.sub.2O without requiring the additional cost of creating a substantially pure oxygen-containing gas flow.

Systems and methods are provided for using a high heat capacity gas as at least a portion of the diluent during the regeneration step of a reverse flow reactor process. Instead of using nitrogen or air as the primary diluent gas, CO.sub.2 and/or H.sub.2O can be added as diluent gas for the regeneration step in the reaction cycle. Increasing the heat capacity of the diluent gas provides a reduction in the peak temperature within the reactor relative to the amount of fuel combusted during regeneration. This can allow for a reduction in the volume of diluent used during regeneration and/or an increase in the amount of fuel used. Reducing the volume of diluent can reduce the pressure drop during regeneration, which can provide a corresponding reduction in the amount of compression required for recycle of the diluent. Increasing the amount of fuel can allow for a corresponding increase in the amount of endothermic reaction performed during the reaction step.

Systems and methods are provided for using a high heat capacity gas as at least a portion of the diluent during the regeneration step of a reverse flow reactor process. Instead of using nitrogen or air as the primary diluent gas, CO.sub.2 and/or H.sub.2O can be added as diluent gas for the regeneration step in the reaction cycle. Increasing the heat capacity of the diluent gas provides a reduction in the peak temperature within the reactor relative to the amount of fuel combusted during regeneration. This can allow for a reduction in the volume of diluent used during regeneration and/or an increase in the amount of fuel used. Reducing the volume of diluent can reduce the pressure drop during regeneration, which can provide a corresponding reduction in the amount of compression required for recycle of the diluent. Increasing the amount of fuel can allow for a corresponding increase in the amount of endothermic reaction performed during the reaction step.

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.

Systems and methods are provided for using a high heat capacity gas as at least a portion of the diluent during the regeneration step of a reverse flow reactor process. Instead of using nitrogen or air as the primary diluent gas, CO.sub.2 and/or H.sub.2O can be added as diluent gas for the regeneration step in the reaction cycle. Increasing the heat capacity of the diluent gas provides a reduction in the peak temperature within the reactor relative to the amount of fuel combusted during regeneration. This can allow for a reduction in the volume of diluent used during regeneration and/or an increase in the amount of fuel used. Reducing the volume of diluent can reduce the pressure drop during regeneration, which can provide a corresponding reduction in the amount of compression required for recycle of the diluent. Increasing the amount of fuel can allow for a corresponding increase in the amount of endothermic reaction performed during the reaction step.

A catalyst system may be regenerated by a method that includes exposing the catalyst system to a de-coking treatment. The de-coking treatment may include three consecutive treatment conditions including a first treatment condition, a second treatment condition, and a third treatment condition. The catalyst system may include a metathesis catalyst and a cracking catalyst. The metathesis catalyst may include tungsten oxide and silica carrier, and the cracking catalyst may include ZSM-5 zeolite.

A catalyst system may be regenerated by a method that includes exposing the catalyst system to a de-coking treatment. The de-coking treatment may include three consecutive treatment conditions including a first treatment condition, a second treatment condition, and a third treatment condition. The catalyst system may include a metathesis catalyst and a cracking catalyst. The metathesis catalyst may include tungsten oxide and silica carrier, and the cracking catalyst may include ZSM-5 zeolite.