Embodiments of methods for capturing high-purity CO.sub.2 in a hydrocarbon facility and related systems are provided. The method comprises operating a hydrogen plant to generate a high-purity hydrogen stream and a CO.sub.2 rich stream with a CO.sub.2 concentration above 30%; introducing the high-purity hydrogen stream into an anode of a molten carbonate fuel cell; introducing the CO.sub.2 rich stream and O.sub.2 into a cathode of the molten carbonate fuel cell; reacting CO.sub.2 and O.sub.2 within the cathode to produce carbonate and a cathode exhaust stream from a cathode outlet; reacting carbonate from the cathode with H.sub.2 within the anode to produce electricity and an anode exhaust stream from an anode outlet, the anode exhaust stream comprising CO.sub.2 and H.sub.2O; separating the CO.sub.2 in the anode exhaust stream in one or more separators to form a pure CO.sub.2 stream and a H.sub.2O stream; and collecting the pure CO.sub.2 stream.

A fuel cell system includes an anode configured to output an anode exhaust stream comprising hydrogen, carbon dioxide, and water; and a membrane dryer configured to receive the anode exhaust stream, remove water from the anode exhaust stream, and output a membrane dryer outlet stream. The membrane dryer includes a first chamber configured to receive the anode exhaust stream; a second chamber configured to receive a purge gas; and a semi-permeable membrane separating the first chamber and the second chamber. The semi-permeable membrane is configured to allow water to diffuse therethrough, thereby removing water from the anode exhaust stream. The membrane dryer may further be configured to remove hydrogen from the anode exhaust stream.

In various aspects, systems and methods are provided for operating a molten carbonate fuel cell, such as a fuel cell assembly, with increased production of syngas while also reducing or minimizing the amount of CO.sub.2 exiting the fuel cell in the cathode exhaust stream. This can allow for improved efficiency of syngas production while also generating electrical power.

Molten carbonate fuel cell configurations are provided that include one or more baffle structures within the cathode gas collection volume. The baffle structures can reduce the unblocked flow cross-section of the cathode gas collection volume by 10% to 80%. It has been discovered that when operating a molten carbonate fuel cell under conditions for elevated CO.sub.2 utilization, the presence of baffles can provide an unexpected benefit in the form of providing increased transference and/or increased operating voltage.

Cathode collector structures and/or corresponding cathode structures are provided that can allow for improved operation for a molten carbonate fuel cell when operated under conditions for elevated CO.sub.2 utilization. A cathode collector structure that provides an increased open area at the cathode surface can reduce or minimize the amount of alternative ion transport that occurs within the fuel cell. Additionally or alternately, grooves in the cathode surface can be used to increase the open area.

Systems and methods are provided for operating molten carbonate fuel cells to allow for periodic regeneration of the fuel cells while performing elevated CO.sub.2 capture. In some aspects, periodic regeneration can be achieved by shifting the location within the fuel cells where the highest density of alternative ion transport is occurring. Such a shift can result in a new location having a highest density of alternative ion transport, while the previous location can primarily transport carbonate ions. Additionally or alternately, periodic regeneration can be performed by modifying the input flows to the fuel cell and/or relaxing the operating conditions of the fuel cell to reduce or minimize the amount of alternative ion transport.

A layered cathode structure for a molten carbonate fuel cell is provided, along with methods of forming a layered cathode and operating a fuel cell including a layered cathode. The layered cathode can include at least a first cathode layer and a second cathode layer. The first cathode layer can correspond to a layer that is adjacent to the molten carbonate electrolyte during operation, while the second cathode layer can correspond to a layer that is adjacent to the cathode collector of the fuel cell. The first cathode layer can be formed by sintering a layer that includes a conventional precursor material for forming a cathode, such as nickel particles. The second cathode layer can be formed by sintering a layer that includes a mixture of particles of a conventional precursor material and 1.0 vol % to 30 vol % of particles of a lithium pore-forming compound. The resulting layered cathode structure can have an increased pore size adjacent to the cathode collector to facilitate diffusion of CO.sub.2 into the electrolyte interface, while also having a smaller pore size adjacent to the electrolyte to allow for improved electrical contact and/or reduced polarization at the interface between the electrolyte and the cathode.

Molten carbonate fuel cells (MCFCs) are operated to provide enhanced CO.sub.2 utilization. This can increase the effective amount of carbonate ion transport that is achieved. The enhanced CO.sub.2 utilization is enabled in part by operating an MCFC under conditions that cause transport of alternative ions across the electrolyte. The amount of alternative ion transport that occurs during enhanced CO.sub.2 utilization can be mitigated by using a more acidic electrolyte.

Systems and methods are provided for using fuel cell staging to reduce or minimize variations in current density when operating molten carbonate fuel cells with elevated CO.sub.2 utilization. The fuel cell staging can mitigate the amount of alternative ion transport that occurs when operating molten carbonate fuel cells under conditions for elevated CO.sub.2 utilization.

A reforming element for a molten carbonate fuel cell stack and corresponding methods are provided that can reduce or minimize temperature differences within the fuel cell stack when operating the fuel cell stack with enhanced CO.sub.2 utilization. The reforming element can include at least one surface with a reforming catalyst deposited on the surface. A difference between the minimum and maximum reforming catalyst density and/or activity on a first portion of the at least one surface can be 20% to 75%, with the highest catalyst densities and/or activities being in proximity to the side of the fuel cell stack corresponding to at least one of the anode inlet and the cathode inlet.