Abstract Oxygen enriched porous carbons have been synthesized by a nanocasting technique using mesoporous zeolite as template and epoxy resin as precursor. Characterization results show the effect of the nanocasting technique on the development of heterogeneous surface, high basicity, and high surface area of 686.37 m2g-1, beneficial for CO2 adsorption. Pure component adsorption isotherms were correlated with Langmuir, Sips, and dual-site Langmuir (DSL) models and found that Sips and DSL isotherm models fitted well, indicating thre heterogeneous nature of the adsorbent surface. Dynamic breakthrough data for the binary system CO2-N2 were obtained using a fixed-bed column at different adsorption temperatures (30-100 °C) and CO2 feed concentrations (5-12.5% by volume). The developed adsorbent shows high adsorption capacity with complete regenerability over four adsorption/desorption cycles. Prediction of binary components (CO2-N2) was made by using extended Sips, extended DSL and IAST (ideal adsorbed solution theory) by utilizing pure component adsorption isotherm data. Experimental and predicted equilibrium data were compared with breakthrough curve data and it was found that the extended forms (Sips and DSL) indicated under-predicted CO2 adsorption equilibria because of differences in adsorptive strengths of CO2 and N2 molecules. Also, adsorption equilibria were closely predicted using IAST theory. Asymmetric x-y diagrams from Raoult’s law indicated positive deviation, implying that as the CO2 gas phase molar fraction increases, total adsorbed amounts increase. Negative values of molar Gibbs free energy change suggested feasibility of the adsorption process. Formation of a more ordered configuration of CO2 molecules on the adsorbent surface was seen as a higher heat of adsorption was exhibited for CO2 as compared to N2.

Abstract Solid-state hydrogen storage is of considerable concern as a potential hydrogen source for portable fuel cell applications. This study mainly focuses on kinetics of NaBH4/Al2O3 nanoparticles (20 nm)/H2O system with CoCl2 as catalyst and the factors that affect the hydrogen generation rate (HGR). It is observed that the reaction rate increases considerably with increase in NaBH4, Al2O3 nanoparticle (20 nm), CoCl2 and NaOH concentrations and the respective reaction orders are calculated. Hydrogen generation rate is also investigated at different temperatures (303, 313, 323 and 333 K) for constant NaBH4 (1.25 moles/L), NaOH (1.4 moles/L), CoCl2 (0.02 moles/L) and Al2O3 (0.09 moles/L) concentrations. Kinetics of the NaBH4 hydrolysis reaction increases with γ-Al2O3 nanoparticles and the calculated activation energy is 29 kJ/moles. This study also reports that a combined dual-solid-fuel system is highly efficient in terms of hydrogen storage capacities compared with a single hydride based system. Maximum hydrogen generation efficiency, observed at a mass ratio of 0.09: 0.7 (Al2O3/NaBH4), is 99.34%.

Abstract A hydrogen generation system based on NaBH4 hydrolysis is affected by the nature of the catalyst and catalyst promoter. Various catalyst promoters such as Al2O3 nanoparticles, Al2O3 particles, ZrO2 sand, SiO2, MMT clay, CNT and zeolite are compared with respect to hydrogen generation (HG) and hydrogen generation rate (HGR). The highest HG and HGR are observed with alumina nanoparticles as compared to other promoters. Cobalt chloride is found to be most efficient catalyst among the other cobalt based salts (CoCl2.6H2O, CoSO4.7H2O, (CH3COO)2Co.4H2O, Co(NO3)2.H2O), cadmium based salt (CdSO4) and copper based salt (CuSO4.5H2O). Maximum HGR obtained is 19.47 moles/L.sec for NaBH4 (1.26 moles/L)/Al2O3 nanoparticles (0.12 moles/L)/H2O and CoCl2.6H2O (0.02 moles/L) as catalyst at room temperature and atmospheric pressure. NaBH4 and alumina hydrolysis reactions, hydrophilic and amphoteric nature of alumina, affinity of Co+2 towards BH4 - ions and formation of aluminates are the factors that promote HGR, as illustrated in this work. Residue obtained from hydrolysis reaction is characterized for its elemental composition by the EDS technique, which confirmed a maximum percentage of boron in the residue. XRD and FTIR results concluded that adsorption of Na+ and Co+ ions occurred on the alumina surface and resulted in the formation of sodium aluminates and cobalt aluminates in the solution.