Estimation-based model predictive control of an electrically-heated steam methane reforming process
Not Available
SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Not Available
Not Available
Explore the source record for details and available documents.
An individual solid oxide cell (SOC) constructed of a sandwich configuration including in the following order: an oxygen electrode, a solid oxide electrolyte, a fuel electrode, a fuel manifold, and at least one layer of mesh. In one embodiment, the mesh supports a reforming catalyst resulting in a solid oxide fuel cell (SOFC) having a reformer embedded therein. The reformer-modified SOFC functions internally to steam reform or partially oxidize a gaseous hydrocarbon, e.g. methane, to a gaseous reformate of hydrogen and carbon monoxide, which is converted in the SOC to water, carbon dioxide, or a mixture thereof, and an electrical current. In another embodiment, an electrical insulator is disposed between the fuel manifold and the mesh resulting in a solid oxide electrolysis cell (SOEC), which functions to electrolyze water and/or carbon dioxide.
With increasing concerns about global warming, the push for sustainable and eco-friendly fuels is accelerating. Propane, recognized as liquefied petroleum gas or LPG, has garnered research interest as an alternative fuel due to its notable advantages, including a high-octane rating, reduced greenhouse gas emissions, and potential cost-effectiveness. However, to realize its full potential as an alternative fuel it is essential to develop catalysts that efficiently handle emissions at low temperatures. In our research, we investigated three distinct palladium (Pd)-based three-way catalyst (TWC) formulations (PdRh, Pd-only, and Pd-OSC) to investigate the influence of typical TWC components rhodium (Rh) and oxygen storage components (OSC) in exhaust scenarios relevant to propane-fueled engines. Among these, the formulation containing oxygen storage components (Pd-OSC) showed the highest reactivity for both NO and C 3 H 8 while minimizing performance degradation from hydrothermal aging (HTA). Notably, the temperature of 50% conversion (T50) for propane in the Pd-OSC fresh and HTA sample was lower by 30 °C and 13 °C, respectively, compared to the Pd-only sample, highlighting the role of oxygen storage materials in enhancing catalyst performance, even without dithering. Additionally, N 2 physisorption showed that the PdOSC sample has a higher surface area and increased pore volume. This underscores the idea that OSC materials not only augment the catalyst’s porosity but also optimize reactant accessibility to active sites, thus elevating catalytic efficiency. In addition to evaluating performance, we further explored the performance and characteristics of the catalysts using catalytic probe reactions, such as water–gas shift and steam reforming reactions.
Performance features are reported for the catalytic sub-stoichiometric (rich) oxidation of methane on a Pt + Pd/ Al 2 O 3 washcoated monolith over a range of feed temperatures and O 2 /CH 4 for both dry and wet feeds. Near isothermal steady state multiplicity and co-existing states with different methane conversions are presented. The methane conversion vs. O 2 feed concentration consists of a higher conversion regime at lower concentrations and a lower conversion, inhibited regime at higher concentration. Here, the conversion maximum is accompanied by an overlap of the two regimes in the form of a clockwise hysteresis loop. Spatial concentration profiles for the dry feed reveal an upstream oxidation zone and downstream stream reforming zone. Measurements extending beyond the catalyst imply the co-existence of active and inhibited states. Addition of water promotes oxidation and steam reforming while the multiplicity and nonuniform states persist. Underlying mechanistic aspects responsible for the inhibition, rate multiplicity and co-existing states are discussed.
The performance, long-term durability, and thermal cycling tolerance of metal supported solid oxide fuel cells (MS-SOFCs) operating with natural gas reformate fuels is assessed. Symmetric MS-SOFCs with composite SDC-Ni anode catalysts and PrO x cathode catalysts are operated with simulated natural gas steam-reformate and partial-oxidation-reformate fuels with 1 ppm and 5 ppm of sulfur. Cells are operated for 1000 h with initial degradation rates similar to humidified H 2 , and initial performance differences attributed to the lower H 2 concentration in reformate fuels. Additionally, cells tolerate many aggressive thermal cycles with sulfur present, with minimal impact on performance. Post mortem analysis suggests that Ni particle coarsening and Cr deposition are sources of degradation, while carbon and sulfur deposition are not observed. Overall, MS-SOFCs operate successfully with reformed natural gas.
The conventional reforming produces H 2 with stoichiometric amounts of CO and CO 2 from hydrocarbons. Here, we show that CO x -free H 2 can be produced from ammonia-assisted reforming (ammoreforming) of natural gas liquids (C n H 2n+2 + nNH 3 = nHCN + (2n + 1) H 2 , n = 2 or 3) at the same conditions as the steam reforming. Such a process co-produces HCN, which can be easily separated from H 2 and used as value-added chemicals or for NH 3 recycling through hydrolysis. In addition, the ammoreforming of ethane and propane was realized over the Re-modified HZSM-5 zeolite rather than the traditional Pt-based catalyst for the BMA process (methane ammoreforming). The specific activity of the Re/HZSM-5 catalysts at 650 °C is up to 1 mol H2 /g Re /min (or 180 min –1 ) during ethane ammoreforming. The catalyst is highly coke resistant and shows only slight deactivation with a time-on-stream up to 20 h. Characterization of the fresh and used catalysts by X-ray absorption and Raman spectroscopies suggested that the isolated ReO x site grafted by AlO 4 – tetrahedral in the zeolite framework is responsible for the outstanding catalytic activity and coke resistibility.
The increasing demand for hydrogen and the CO2 intensity of natural gas (NG) reforming motivate the development of low-carbon-emission hydrogen production technologies. Gas Switching Reforming (GSR) is an advanced auto-thermal reforming technology that produces hydrogen or syngas from natural gas. It integrates inherent CO2 capture by utilizing a specialized oxygen carrier in a single fluidized bed reactor, eliminating the need for complex, energy-intensive post-combustion separation. GSR technology builds upon Chemical Looping Reforming (CLR), an experimentally proven technology with strong potential for scaling up. In this study, select oxygen carriers (OC) (NiO/Al2O3, Fe2O3-CeO2/Al2O3, and magnetite) were tested in methane steam reforming in a fixed bed reactor to determine their relative reactivities under relevant conditions for GSR (800 °C, 7 bar total pressure). Process models were then developed to perform techno-economic analysis (TEA) of GSR for hydrogen production (GSR-H₂) and a combined cycle (GSR-CC) in which high-purity H₂ is fired in a gas turbine to produce electricity. Operating at 10 bar and 1100 °C and with the additional recovery steps implemented increased H₂ production by ~30% and improved efficiency relative to prior studies. For GSR-H₂, the levelized cost of hydrogen (LCOH) is 1.61–1.64 $/kg-H₂, competitive with a reference SMR case, though operating and maintenance costs are higher due to increased electricity demand. GSR-CC has a significantly higher levelized cost of electricity (LCOE) than its reference NGCC (natural gas combined cycle) plant, suggesting it is less competitive; however, increasing production scale could make it more attractive. Life-cycle results for GSR-H2 indicate NG consumption drives ~75% of total global warming impacts (~2.3 kg CO2 eq/kg H2). An environmental, health, and safety screening suggests iron-based carriers are comparatively safer, whereas NiO may pose greater risks. Overall, GSR-H2 is a scalable, competitive option for hydrogen production using nickel and non-nickel OC.
GTI Energy has integrated the Cool Reformer technology with the IH 2® -50 pilot plant (which can process a maximum of 50kg/day of biomass feed) to demonstrate the suitability of this new reforming technology for producing hydrogen within IH 2 ® process. As part of this study, we showed that all of the hydrogen required for the IH 2® process could be produced from steam reforming the IH 2® light gas generated within the process and the system can be integrated in a cost-effective way compared to the use of standard SMRs.
The increasing demand for hydrogen and the CO2 intensity of natural gas (NG) reforming motivate the development of low-carbon-emission hydrogen production technologies. Gas Switching Reforming (GSR) with integrated CO2 capture, a technology based on Chemical Looping Reforming (CLR), has been experimentally proven and shows potential for scale-up. In this study, select oxygen carriers (OC) (NiO/Al2O3, Fe2O3-CeO2/Al2O3, and magnetite) were tested in methane steam reforming in a fixed bed reactor to determine their relative reactivities under relevant conditions for GSR (800 °C, 7 bar total pressure). Process models were then developed to perform techno-economic analysis (TEA) of GSR for hydrogen production (GSR-H2) and a combined cycle (GSR-CC) in which high-purity H2 is fired in a gas turbine to produce electricity. Operating at 10 bar and 1100 °C and with the additional recovery steps implemented increased H2 production by ∼ 30% and improved efficiency relative to prior studies. For GSR-H2, the levelized cost of hydrogen (LCOH) is 1.61–1.64 $/kg-H2, competitive with a reference SMR case, though operating and maintenance costs are higher due to increased electricity demand. GSR-CC has a significantly higher levelized cost of electricity (LCOE) than its reference NGCC (natural gas combined cycle) plant, suggesting it is less competitive; however, increasing production scale could make it more attractive. Life-cycle results for GSR-H2 indicate NG consumption drives ∼ 75% of total global warming impacts (∼2.3 kg CO2 eq/kg H2). An environmental, health, and safety screening suggests iron-based carriers are comparatively safer, whereas NiO may pose greater risks. Overall, GSR-H2 is a scalable, competitive option for hydrogen production using nickel and non-nickel OC.
Microwave absorbing catalysts have the potential to make thermal reactions such as methane reforming (CH4 + CO2 + H2O → H2 + CO) into carbon negative processes when coupled with decarbonized electricity. Due to microwaves directly heating the catalyst rather than heating the reactor and gases, even high temperature reactions such as dry reforming methane (DRM, CH4 + CO2 → H2 + CO) can be achieved rapidly, efficiently, and on-demand, ideal for coupling with intermittent renewable electricity. However, microwave catalysts present unique design challenges due to the same material needing to both efficiently absorb microwaves in oxidative and reductive reaction conditions and be an efficient and stable catalyst in inherently non-isothermal reactors. We screened from over 28 catalysts in the La0.8Sr0.2(Co-Ni-Mn)O3 perovskite solid-solution family to determine promising microwave reforming catalysts and identify design principles for effective materials. The best performing catalyst candidate was able to produce syngas ratios (H2:CO) from 1-3, and scale up testing showed CO and H2 production efficiencies rivaling conventional carbon intensive steam reforming efficiencies at the liters per minute level of production.
The increasing demand for hydrogen and the CO 2 intensity of natural gas (NG) reforming motivate the development of low-carbon-emission hydrogen production technologies. Gas Switching Reforming (GSR) with integrated CO 2 capture, a technology based on Chemical Looping Reforming (CLR), has been experimentally proven and shows potential for scale-up. In this study, select oxygen carriers (OC) (NiO/Al 2 O 3 , Fe 2 O 3 -CeO 2 /Al 2 O 3 , and magnetite) were tested in methane steam reforming in a fixed bed reactor to determine their relative reactivities under relevant conditions for GSR (800 °C, 7 bar total pressure). Process models were then developed to perform techno-economic analysis (TEA) of GSR for hydrogen production (GSR-H 2 ) and a combined cycle (GSR-CC) in which high-purity H 2 is fired in a gas turbine to produce electricity. Operating at 10 bar and 1100 °C and with the additional recovery steps implemented increased H 2 production by ∼ 30% and improved efficiency relative to prior studies. For GSR-H 2 , the levelized cost of hydrogen (LCOH) is 1.61–1.64 $/kg-H 2 , competitive with a reference SMR case, though operating and maintenance costs are higher due to increased electricity demand. GSR-CC has a significantly higher levelized cost of electricity (LCOE) than its reference NGCC (natural gas combined cycle) plant, suggesting it is less competitive; however, increasing production scale could make it more attractive. Life-cycle results for GSR-H 2 indicate NG consumption drives ∼ 75% of total global warming impacts (∼2.3 kg CO 2 eq/kg H 2 ). An environmental, health, and safety screening suggests iron-based carriers are comparatively safer, whereas NiO may pose greater risks. Overall, GSR-H 2 is a scalable, competitive option for hydrogen production using nickel and non-nickel OC.
In the current energy and environment scenario, it is imperative to develop energy efficient routes for chemical manufacturing that also pave the way for mitigation of greenhouse gas emissions. This work presents an efficient pathway for continuous syngas production via a chemical looping conversion of the two most potent greenhouse gases—CH 4 , and CO 2 . The well-known dry-reforming process of converting CH 4 , and CO 2 to syngas is energy-intensive and suffers from catalyst deactivation. The chemical looping approach, on the other hand, provides avenues for mitigating catalyst deactivation and enabling improved energy efficiency. The key to such process enhancements lies in the intricate structure–function relationships of the catalyst and its correlation to the process variables. We present the reduction and oxidation characteristics of 5 wt.% Ni/Ce 1-x Zr x O 2 -based catalysts (x = 0, 0.4, and 0.625). We demonstrate low temperature CH4 activation over Ni-promoted samples as opposed to pure Ce 1-x Zr x O 2 . Moreover, our results depict an optimum regeneration of these catalysts when oxidized by CO 2 , and H 2 O, which allows for chemical looping operation of steam reforming of methane as well. Process variables were tuned to optimize the CH 4 conversion (over 80%), and H 2 /CO ratio at 650 °C. The critical surface reactions—carbon accumulation and gasification, and thermocatalytic CO 2 splitting were investigated to elucidate the dynamic nature of the catalyst surface. In conclusion, the impact of this work lies in showcasing the opportunities to design chemical looping reactors for energy efficient syngas production from waste greenhouse gases.
The Integrated Waste Treatment Unit (IWTU) has been tasked with using steam reforming technology to treat 3.4 million liters (900,000 gallons) of radioactive sodium-bearing waste (SBW) at the Idaho National Laboratory (INL). The project has been hampered by a number of processing issues associated with process equipment during simulant testing, with the two main issues involving the fluidizing gas distribution system in the main reactor vessel, the denitration mineralization reformer (DMR), and high differential pressures in the main filter vessel, the process gas filter (PGF). Following the replacement of the fluidizing gas distribution system in the DMR, a successful 30-day demonstration run was performed that revealed unacceptable bridging in the filter bundles of the PGF. The bundles were replaced with new ones, and a 50-day demonstration run was performed. The main purpose of this run was to operate the IWTU over a range of operating conditions. Overall, the run was a success; however, there were multiple challenges that arose from the run. (authors)
Sorption‐enhanced steam reforming and gasification using CO 2 sorbents enable the production of H 2 ‐rich syngas from carbonaceous feedstocks but are limited by significant temperature swings and sintering‐induced activity loss. Perovskite‐structured oxides are presented herein as sintering‐resistant, redox‐activated isothermal CO 2 sorbents capable of overcoming these challenges by releasing lattice oxygen to partially oxidize the carbonaceous feedstock while capturing CO 2 , shifting equilibrium toward H 2 production. Building on this, the structural and thermodynamic impact of Fe doping on the CO 2 sorption properties of SrMn 1‐ x Fe x O 3‐ δ is investigated for sorption‐enhanced reforming. Experimental results demonstrate that these sorbents enable isothermal production of high‐quality, H 2 ‐enriched syngas from carbonaceous feedstocks. Laboratory and synchrotron‐based powder X‐ray diffraction analyses, coupled with density functional theory calculations, reveal the structural dynamics and energy landscape of the SrMn 1‐ x Fe x O 3‐ δ perovskite system under reaction conditions, elucidating the solid‐state reaction pathway and the effect of Fe doping on the extent of carbonation.
Fractal structures which display nearly the same character at every scale exist widely in nature, however, it is still a great challenge to fabricate a fractal nanostructure. Herein, a Y 2 O 3 monolith with unique hierarchically fractal porous structure was fabricated via calcination of a fractal porous coordination polymer precursor. The monolith exhibits porous feature with the pore-size ranging from micrometers to nanometers. Interestingly, each level of the pore-wall is composed of secondary porous structures, whose pore-wall is composed of sub-level self-similar porous feature. Moreover, by Ni-doping in the coordination polymer precursor, fractal porous Ni@Y 2 O 3 was prepared, and exhibited enhanced activity in ethanol steam reforming compared with that of a common supported NiO catalyst.
We report efficient lean-burn gasoline engines cannot employ traditional three-way catalysts (TWCs) to control NO X emissions due to excess oxygen. Passive selective catalytic reduction (pSCR) is a process designed to control NOx by generating NH 3 over the TWC during fuel-rich operation, storing it on a downstream SCR, and then converting NOx during fuel-lean operation. This work is focused on studying sulfur effects on this promising strategy. Two hydrothermally-aged commercial catalysts were studied for their effectiveness in the presence of SO 2 : a Pd-based TWC and a TWC with NO X storage. The sulfated samples were evaluated in a flow reactor under pSCR conditions and with targeted reactions. SO 2 inhibited the water gas shift and steam reforming reactions, decreasing (but not eliminating) NH 3 production; however, initial activity is recoverable after a simple thermal treatment at 650 °C. This work will prove valuable in understanding, mitigating, and even reversing the effects of SO 2 inhibition on real pSCR systems.