Large Quantities Of H2 Research Articles

Hydrogen Flooding of a Coal Core: Effect on Coal Swelling

AbstractHydrogen is a clean fuel which has the potential to drastically decarbonize the energy supply chain. However, hydrogen storage is currently a key challenge; one solution to this problem is hydrogen geo‐storage, with which very large quantities of H2 can be stored economically. Possible target formations are deep coal seams, and coal permeability is a key parameter which determines how fast H2 can be injected and withdrawn again. However, it is well known that gas injection into coal can lead to coal swelling, which drastically reduces permeability. We thus injected H2 gas into a coal core and measured dynamic permeability, while imaging the core via x‐ray micro‐tomography at reservoir conditions. Importantly, no changes in coal cleat morphology or permeability were observed. We conclude that H2 geo‐storage in deep coal seams is feasible from a fundamental petro‐physical perspective; this work thus aids in the large‐scale implementation of a hydrogen economy.

Optimum geological storage depths for structural H2 geo-storage

H2 geo-storage has been suggested as a key technology with which large quantities of H2 can be stored and withdrawn again rapidly. One option which is currently explored is H2 storage in sedimentary geologic formations which are geographically widespread and potentially provide large storage space. The mechanism which keeps the buoyant H2 in the subsurface is structural trapping where a caprock prevents the H2 from rising by capillary forces. It is therefore important to assess how much H2 can be stored via structural trapping under given geo-thermal conditions. This structural trapping capacity is thus assessed here, and it is demonstrated that an optimum storage depth for H2 exists at a depth of 1100 m, at which a maximum amount of H2 can be stored. This work therefore aids in the industrial-scale implementation of a hydrogen economy.

Capture and storage of hydrogen gas by zero-valent iron

Granular Fe(o), used to reductively degrade a variety of contaminants in groundwater, corrodes in water to produce H2(g). A portion enters the Fe(o) lattice where it is stored in trapping sites such as lattice defects and microcracks. The balance is dissolved by the groundwater where it may exsolve as a gas if its solubility is exceeded. Gas exsolution can reduce the effectiveness of the Fe(o) treatment zone by reducing contact of the contaminant with iron surfaces or by diverting groundwater flow. It also represents a lost electron resource that otherwise could be involved in reductive degradation of contaminants. It is advantageous to select an iron for remediation purposes that captures a large proportion of the H2(g) it generates. This study examines various aspects of the H2(g) uptake process and has found 1) H2(g) does not have to be generated at the water/iron interface to enter the lattice. It can enter directly from the gas/water phases, 2) exposure of granular sponge iron to H2(g) reduces the dormant period for the onset of iron corrosion, 3) the large quantities of H2(g) generated by nano-Fe(o) injected into a reactive barrier of an appropriate granular iron can be captured in the lattice of that iron, and 4) lattice-bound hydrogen represents an additional electron resource to Fe(o) for remediation purposes and may be accessible using physical or chemical means.

Surface Sites of Pd/CeO2/Al2O3 Catalysts in the Partial Oxidation of Propane

Propane oxidation was studied on a Pd-supported Al2O3 catalyst promoted by ceria, when this ceria was first grafted as a monolayer over alumina. The reaction proceeded under different feed conditions, and the surface sites were identified by X-ray photoelectron spectroscopy (XPS) in a pretreatment chamber and then compared to temperature-programmed desorption, temperature-programmed surface reaction (TPSR), and catalytic results, in the presence and absence of water. Stable catalyst performance was achieved in experiments after 20 h with time on stream, to get reliable data for further interpretation. This observation is true for all reaction conditions, with reducing, stoichiometric, or excess oxygen content in the reaction feed. The Pd/CeO2/Al2O3 catalyst is less active for oxidation at low temperatures but suddenly becomes very active at high temperatures. However, in the case of the latter, large quantities of H2 were released, which suggests a drastic change in selectivity. TPSR results showed that t...

Stepwise thermal degradation of a polybenzimidazole foam

AbstractThe stepwise thermal degradation of a polybenzimidazole (PBI) foam, prepared from 3,3′‐diaminobenzidine and isophthaldiamide, has been studied under conditions of pyrolysis and nonflaming oxidative degradation in a thermal analyzer using gas and liquid chromatographic separation and mass spectrometric and infrared detection techniques. The recoveries of sample weight, as degradation products, were quantitative over the entire temperature ranges studied (100–300, 300–570, 570–700, and 700–1000°C for pyrolysis; and 100–570 and 570–900°C for nonflaming oxidation). In pyrolysis, 17 volatile compounds were identified with NH3 and CH4 accounting for 94 and 57 mole % of the total mass loss between 300–570 and 570–700°C, respectively. Above 700°C, HCN and H2 were formed from degradation of arylnitrile‐containing oligomers. The thermal and oxidative degradation of three substituted benzimidazole monomers was also studied, and the relative ratios of N2, NH3, and HCN that were produced from each, when compared with PBI, support a mechanism for degradation that favors cleavages that least alter the conjugation of the polymer backbone. In the presence of air, PBI formed stable oxygen‐containing residues that decomposed at high temperatures to N2, CO2, and H2O almost exclusively. Large quantities of H2 and N2 from model compounds support results from PBI that suggest that degradation begins with total erosion of the imide ring at 570°C and the formation of more condensed heterocyclic species. These quantitative techniques are generally applicable to the study of all polymeric materials.