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Kinetic study of ethanol steam reforming over a commercial nickel−magnesia−alumina (Ni/MgO/Al2O3) catalyst was conducted in a fixed-bed reactor 15 mm in diameter. The effects of temperature (673−873 K), molar ratio of steam to ethanol in the feed (in the range of 3:1 to 18:1), feed flow rate (W/F EtOH = 46.2−555.25 g-cat min/mol), catalyst particle size (2.25−0.75 mm), and time-on-stream study was studied. Maximum conversion (>95%) was obtained at 873 K, with a molar ratio of steam to ethanol of 12:1 and a W/F EtOH value of >185 g-cat min/mol at atmospheric pressure. A maximum yield of 3.0 moles of hydrogen per mole of ethanol fed was obtained at a temperature of 873 K, a steam-to-ethanol molar feed ratio of 12:1, and a W/F EtOH value of >110 g-cat min/mol. The acquired data was fitted to a power-law kinetic model and the kinetic parameters were evaluated. The activation energy was determined to be 23 kJ/mol. The average absolute deviation (AAD) for the predicted rates of reaction was determined to be 10.2%. The work also tested the feasibility of using the Eley−Rideal mechanism proposed in the literature and concludes that a more-elaborate scheme of reactions is necessary to describe the complex reactions that occur during the steam reforming process. A considerable amount of coke formation was observed during the process; yet, the catalyst showed a negligible loss of activity, exhibiting the feasibility of using this catalyst for ethanol steam reforming. In an attempt to reduce this coke formation, it is suggested that the process may be performed in the presence of hydrogen gas.

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The σ-aromaticity of M3(+) (M = Cu, Ag, Au) is analyzed and compared with that of Li3(+) and a prototype σ-aromatic system, H3(+). Ligands (L) like dimethyl imidazol-2-ylidene, pyridine, isoxazole and furan are employed to stabilize these monocationic M3(+) clusters. They all bind M3(+) with favorable interaction energy. Dimethyl imidazol-2-ylidene forms the strongest bond with M3(+) followed by pyridine, isoxazole and furan. Electrostatic contribution is considerably more than that of orbital contribution in these M-L bonds. The orbital interaction arises from both L → M σ donation and L ← M back donation. M3(+) clusters also bind noble gas atoms and carbon monoxide effectively. In general, among the studied systems Au3(+) binds a given L most strongly followed by Cu3(+) and Ag3(+). Computation of the nucleus-independent chemical shift (NICS) and its different extensions like the NICS-rate and NICS in-plane component vs. NICS out-of-plane component shows that the σ-aromaticity in L bound M3(+) increases compared to that of bare clusters. The aromaticity in pyridine, isoxazole and furan bound Au3(+) complexes is quite comparable with that in the recently synthesized Zn3(C5(CH3)5)3(+). The energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital also increases upon binding with L. The blue-shift and red-shift in the C-O stretching frequency of M3(CO)3(+) and M3(OC)3(+), respectively, are analyzed through reverse polarization of the σ- and π-orbitals of CO as well as the relative amount of OC → M σ donation and M → CO π back donation. The electron density analysis is also performed to gain further insight into the nature of interaction.

A density functional theory-based computation has been carried out to reveal the geometrical and electronic structures of Mg 2 EP ( 1 ), where EP is an extended (3.1.3.1) porphyrinoid system. EP is a 22 π electronic system and is aromatic in nature. Here, we have studied the thermodynamic and kinetic stabilities of EP 2– -supported Mg 2 2+ ion. The nature of bonding has been studied using natural bond orbital and atoms in molecule schemes. The presence of a covalent Mg(I)–Mg(I) σ-bond in Mg 2 EP is confirmed. The occurrence of a non-nuclear attractor (NNA) with large electron population, negative Laplacian of electron density at NNA, and presence of an electron localization function basin along with large nonlinear optical properties prompt us to classify Mg 2 EP as the first porphyrinoid-based organic electride. Further five small molecules, viz., dihydrogen (H 2 ), carbon dioxide (CO 2 ), nitrous oxide (N 2 O), methane (CH 4 ), and benzene (C 6 H 6 ), are found to be activated by the electron density between the two Mg atoms in Mg 2 EP.