Dispersion of calcium oxide on high surface area γ-Al2O3 creates a stable and reversible CO2−sorbent that overcomes the problems associated with bulk CaO, such as limited long-term stability, slow uptake kinetics, and energy-intensive regeneration. This sorbent is a candidate for the sorption-enhanced hydrogen production via steam reforming and/or water-gas shift reactions. CO2 uptake tests were performed in a 15% CO2/N2 atmosphere to evaluate the efficacy at typical hydrocarbon reformer gas partial pressure. CO2 uptake kinetics and capacities are investigated in TGA studies, while the long-term stability is shown in multicycle experiments. The dispersed CaO is an active sorbent at low temperatures and binds CO2 at 300 °C up to 1.7 times as efficiently as compared to bulk CaO powder. Furthermore, the sorbent can be regenerated in a CO2-free atmosphere at intermediate temperatures between 300 and 650 °C. Multicycle CO2 uptake and release has been tested for 84 cycles at a constant temperature of 650 °C and shows the superior long-term stability of dispersed CaO as compared to bulk CaO. The attempt to increase the uptake capacity from 0.16 to 0.22 mmol CO2 per gram of sorbent occurred with a commensurate loss in BET area from 115 to 41 m2, leading to a decline in overall uptake efficiency from 15% to 6%. Infrared spectroscopy is used to characterize the CO2−sorbent binding interaction on a molecular level and to distinguish between CO2 adsorbing on the bare support, on bulk CaO, and on dispersed CaO/Al2O3.

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A 72 L large-scale reactor vessel was designed, manufactured, and built to investigate the gas production from methane gas hydrates. Methane hydrates were successfully formed within the reactor using pure methane gas and deionized water in a sand matrix with grain sizes between 100 and 500 μm. Hydrate formation tests resulted in formation at 2.2 °C around 600 psi. Mass balance calculations show that 11% of the pore space volume was occupied by hydrate. Measurements and simulations suggest that hydrate was initially formed at the top section of the reactor followed by formation within the lower part of the sediment. A cooling effect was observed during the dissociation via depressurization experiments, caused by the endothermic dissociation reaction. The observed temperature decrease of the system was between 4.0 and 0.8 °C. During the hydrate dissociation tests, a transition regime showing an increased gas production from 9.5 to 13 L/min within a very narrow range of temperature between −1.6 and −1.2 °C and pressure between 310 and 360 psi was recorded. In addition, the temperature was observed to jump to 0 °C in an extremely short time period. The interpretation of this phenomenon is ice formation in the transition regime where hydrate decomposes to gas and ice instead of gas and liquid. This is the first experimental observation of this phenomenon.

In situ capture of CO 2 allows the thermodynamically constrained water gas shift (WGS) process to operate at higher temperatures (i.e., 350°C) where reaction kinetics are more favorable. Dispersed CaO/γ-Al 2 O 3 was investigated as a sorbent for in situ CO 2 capture for an enhanced water gas shift application. The CO 2 adsorbent (CaO/γ-Al 2 O 3 ) and WGS catalyst (Pt/γ-Al 2 O 3 ) were integrated as multiple layers of washcoats on a monolith structure. CO 2 capture experiments were performed using thermal gravimetric analysis (TGA) and a bench scale flow through reactor. Enhancement of the water gas shift (EWGS) reaction was demonstrated using monoliths (400 cells/in. 2 ) washcoated with separate layers of dispersed CaO/γ-Al 2 O 3 and Pt/γ-Al 2 O 3 in a flow reactor. Capture experiments in a reactor using monoliths coated with CaO/γ-Al 2 O 3 indicated that increased concentrations of steam in the reactant mixture increase the capture capacity of the CO 2 adsorbent as well as the extent of regeneration. A maximum capture capacity of 0.63 mol of CO 2 /kg of sorbent (for 8.4% CaO on γ-Al 2 O 3 washcoated with a loading of 3.45 g/in. 3 on monolith) was observed at 350°C for a reactant mixture consisting of 10% CO 2 , 28% steam, and balance N 2 . Hydrogen production was enhanced in the presence of monoliths coated with a layer of 1% Pt/γ-Al 2 O 3 and a separate layer of 9.4% CaO/γ-Al 2 O 3 . A greater volume of hydrogen compared to the baseline WGS case was produced over a fixed amount of time for multiple cycles of EWGS. The CO conversion was enhanced beyond equilibrium during the period of rapid CO 2 capture by the nanodispersed adsorbent. Following saturation of the adsorbent, the monoliths were regenerated (CO 2 was released) in situ, at temperatures far below the temperature required for decomposition of bulk CaCO 3 . It was demonstrated that the water gas shift reaction could be enhanced for at least nine cycles with in situ regeneration of adsorbent between cycles. Isothermal regeneration with only steam was shown to be a feasible method for developing a process.