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The quantum calculation gives the insight of reaction mechanism in chemistry. In this work, we predict hydrogen evolution reaction (HER) mechanism in Ni(abt)2 (abt = 2‐aminobenzenethiolate) catalyst. Using density functional theory (DFT) and coupled‐cluster singles, doubles and perturbative triples (CCSD(T)) methods, we demonstrate the potential energy surface (PES) for the HER reaction result with two intermediate states (IM) and transition states (TS). Our result shows that the hydrogen atoms are migrated to Ni atom one by one from each of two amino groups. It indicates that the HER reaction in Ni(abt)2 occurs following the ligand‐assisted metal‐centered H2 production. Finally, two hydrogen atoms are merged in Ni atom site which generates hydrogen molecule. This would be meaningful prediction to understand the role of metal catalyst in HER reaction pathway. [ABSTRACT FROM AUTHOR]

Ni/ CeO2 catalysts with different Ni loadings (5, 7, 10, 12, and 14 wt% Ni) were prepared by an impregnation method and examined for the CO2 reforming of methane using flow and static reactors. Their catalytic activities and selectivities were measured under CO2/ CH4/Ar (=5/5/40 cm3/min) flow at 450-800°C using a flow reactor system with an on-line gas chromatography. At fixed temperature, the CO2 and CH4 conversions varied only slightly with the Ni wt%, whereas the H2/ CO ratio increased with increasing Ni wt%. The conversions increased with temperature, reaching 98% at 800°C. The H2/ CO ratio varied with temperature in the range of 450-800°C, from less than 1 below 550°C to close to 1 at 550-600°C and then back to less than 1 above 600°C. The apparent activation energies were determined to be 43.1 kJ/mol for the CO2 consumption and 50.2 kJ/mol for the CH4 consumption based on the rates measured for the reforming reaction over 5 wt% Ni/ CeO2 catalyst at 550-750°C. Additionally, the catalytic reforming reaction at low pressure (40 Torr) was investigated by a static reactor system by using a differential photoacoustic cell, in which the rates were measured from the CO2 photoacoustic signal data at early reaction times over the temperature range of 460-610°C. Apparent activation energies of 25.5-30.1 kJ/mol were calculated from the CO2 disappearance rates. The CO2 adsorption on the Ni/ CeO2 catalyst was investigated by the CO2 photoacoustic spectroscopy and Fourier transform infrared spectroscopy. Feasible side reactions during the catalytic CO2/ CH4 reaction were suggested on the basis of the kinetic and spectroscopic results. [ABSTRACT FROM AUTHOR]

The second-order rate constants for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates ( 4a-4f) and Y-substituted-phenyl-4-nitrobenzenesulfonates ( 5a-5f) with [ABSTRACT FROM AUTHOR]

Second-order rate constants ( kOH-) for alkaline hydrolysis of Y-substituted phenyl picolinates ( 6a-6i) have been measured spectrophotometrically. A linear Brønsted-type plot is obtained with βlg = −0.34, which is typical for reactions reported previously to proceed through a stepwise mechanism with formation of an addition intermediate being the rate-determining step ( RDS). However [ABSTRACT FROM AUTHOR]

Second-order rate constants ( kquin) for the reactions of O- Y-substituted phenyl thionobenzoates ( 3a-3i) with quinuclidine have been measured spectrophotometrically. Comparison of kquin with the rate constants reported previously for the corresponding reactions with benzylamine ( kBzNH2) has revealed that quinuclidine is less reactive than benzylamine toward 3a-3i although the former is 2.1 p Ka units more basic than the latter. Steric hindrance exerted by quinuclidine has been suggested to be responsible for the decreased reactivity of the tertiary amine. The Brønsted-type plot for the reactions of 3a-3i with quinuclidine is linear with βlg = −0.37. The Hammett plot correlated with [ABSTRACT FROM AUTHOR]

Pseudo-first-order rate constants (kobsd) have been measured spectrophotometrically for the reactions of 5-nitro-8-quinolyl nicotinate (4) and 5-nitro-8-quinolyl isonicotinate (5) with alkali metal ethoxides (EtOM; M = K, Na and Li) in anhydrous ethanol at 25.0 ± 0.1°C. The plots of kobsd vs. [EtOM] curve slightly upward for the reactions with EtOK and EtONa but are linear for the reactions with EtOLi and for those with EtOK in the presence of 18-crown-6-ether. Dissection of kobsd into ... and kEtOM (i.e., the second-order rate constants for the reactions with the dissociated EtO- and ion-paired EtOM, respectively) has revealed that the reactivity increases in the order EtO- ≈ EtOLi < EtOK < EtONa for the reactions of 4 and EtOLi < EtO- < EtOK < EtONa for the reactions of 5. Comparison of the kinetic results for the reactions of 4 and 5 with those reported previously for the corresponding reactions of 5-nitro-8-quinolyl benzoate (2) and picolinate (3) has revealed that the esters possessing a pyridine ring (i.e., 3-5) are significantly more reactive than the benzoate ester 2 due to the presence of the electronegative N atom (e.g., 2 << 3 < 4 < 5). It has been concluded that M+ ion catalyzes the reactions of 3-5 by increasing the electrophilicity of the reaction center through a five-membered cyclic transition state (TS) for the reaction of 3 and via a four-membered cyclic TS for the reactions of 4 and 5. [ABSTRACT FROM AUTHOR]