A method of recovering paraxylene in a pressure swing adsorption unit with varying hydrogen purge pressures. The pressure swing adsorption zone is adapted to adsorb and desorb paraxylene based on the cycling of partial pressure in the zone. A first hydrogen purge is fed concurrent to the feed. A second hydrogen purge is countercurrent to the feed.

A method of recovering paraxyiene in a pressure swing adsorption unit with varying hydrogen purge pressures. The pressure swing adsorption zone is adapted to adsorb and desorb paraxyiene based on the cycling of partial pressure in the zone. A first hydrogen purge fed to the zone is within 50 psi of the adsorption pressure of paraxyiene in the zone. A second hydrogen purge fed to the zone is within 50 psi of the desorption pressure of paraxyiene in the zone. The overall amount of hydrogen necessary to operate the pressure swing adsorption zone is reduced and heat may be recovered from the effluent leaving the pressure swing adsorption zone.

A method of recovering paraxyiene in a pressure swing adsorption unit with varying hydrogen purge pressures. The pressure swing adsorption zone is adapted to adsorb and desorb paraxyiene based on the cycling of partial pressure in the zone. A first hydrogen purge fed to the zone is within 50 psi of the adsorption pressure of paraxyiene in the zone. A second hydrogen purge fed to the zone is within 50 psi of the desorption pressure of paraxyiene in the zone. The overall amount of hydrogen necessary to operate the pressure swing adsorption zone is reduced and heat may be recovered from the effluent leaving the pressure swing adsorption zone.

A process for combusting coke from catalyst in partial burn mode is disclosed. The regenerator comprises two chambers. The bulk of the combustion is performed in a first chamber. Disengagement of the catalyst from gas is conducted in the second chamber. Heated gas with a low fraction of oxygen fluidizes catalyst in the second chamber.

According to an exemplary embodiment of the present invention, a pressure swing adsorption process of a hydrogen production system is provided. The hydrogen production system includes a desulfurization process for removing sulfur components from raw natural gas; a reforming reaction process for producing a reformed gas containing hydrogen generated by the reaction of natural gas through the desulfurization process and steam; and a pressure swing adsorption process of concentrating the hydrogen using a pressure swing adsorption from the reformed gas. In a desorption step of the pressure swing adsorption process, a cocurrent depressurization and a countercurrent depressurization are simultaneously performed.

Pressure swing adsorption process for reducing fluctuations in the flow rate of tail gas from the adsorption unit. The flow rate of the stream of blowdown gas is regulated responsive signals from a sensor measuring the pressure and/or flow rate of the tail gas comprising the blowdown gas and purge gas effluent before the tail gas is introduced into a surge vessel.

Disclosed herein are multi-bed rapid cycle pressure swing adsorption (RCPSA) processes for separating O.sub.2 from N.sub.2 and/or Ar, wherein the process utilizes at least five adsorption beds each comprising a kinetically selective adsorbent for O.sub.2 having an O.sub.2 adsorption rate (1/s) of at least 0.20 as determined by linear driving force model at 1 atma and 86 F.

Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve performing dampening for fluctuations in the streams conducted away from the adsorbent bed unit. The process may be utilized for swing adsorption processes, such as rapid cycle TSA and/or rapid cycle PSA, which are utilized to remove one or more contaminants from a gaseous feed stream.

Disclosed herein are multi-bed rapid cycle pressure swing adsorption (RCPSA) processes for separating O.sub.2 from N.sub.2 and/or Ar, wherein the process utilizes at least five adsorption beds each comprising a kinetically selective adsorbent for O.sub.2 having an O.sub.2 adsorption rate (1/s) of at least 0.20 as determined by linear driving force model at 1 atma and 86 F.

Methods and systems for capture of CO.sub.2 from a hydrated gaseous stream are described. Systems can be utilized for direct air capture of CO.sub.2 and incorporate a low energy temperature-vacuum swing adsorption (TVSA) process. A TVSA process can include a multi-step CO.sub.2 capture bed regeneration process that includes depressurization of the bed, heating of the bed, venting and purging of the bed, and cooling of the bed. Multiple beds can be cycled between CO.sub.2 capture and regeneration, during which captured CO.sub.2 is recovered. Off-gas from a CO.sub.2 capture bed can be used in regenerating a parallel bed for increased efficiency.