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18. Termolecular Eley–Rideal pathway for catalytic oxidation of nitric oxide on [Pt2]0,± dimers using O2.

Author

Biswakarma, Nishant, Sarma, Plaban Jyoti, Neog, Shilpa, Dutta, Priyanka, Dowerah, Dikshita, Baruah, Satyajit Dey, Gour, Nand Kishor, and Deka, Ramesh Chandra

Subjects
CATALYTIC oxidation, CHEMICAL models, NITRIC oxide, CHEMICAL processes, DIMERS, DENSITY functional theory
Abstract

A comprehensive density functional theory (DFT) investigation of the catalytic oxidation of NO to NO2 on neutral and charged [Pt2]0,± dimers has been considered employing M06L/def2TZVP level of theory. Single as well as co‐adsorption energies of NO and O2 molecules suggest that the traditional Langmuir Hinshelwood (LH) mechanism and less explored termolecular Eley–Rideal (TER) and termolecular Langmuir Hinshelwood (TLH) mechanisms, are suitable for a full catalytic reaction pathway in which two NO molecules are converted to two NO2 molecules, initiated by an activated O2 molecule. Activation barrier reveals that the TER mechanism is found to be more reliable in converting two NO molecules into two NO2 molecules on [Pt2]¯ dimer. In addition to shedding light on the intrinsic characteristics of Pt2 dimers, the study will serve as a benchmark for investigating the oxidation process of NO to NO2 utilizing models of termolecular chemical processes. [ABSTRACT FROM AUTHOR]

Published
2024
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19. One‐Pot N‐Alkylation of Amines over Ni(II) Embedded Reusable Porous Organic Polymer via Borrowing Hydrogen Strategy.

Author

Pathak, Debabrat, Kumar Kalita, Bikash, Sharma, Himanshu, Biswakarma, Nishant, Deka, Ramesh Ch., and Sarma, Bipul

Subjects
POROUS polymers, HYDROGEN, ALCOHOL oxidation, DEHYDROGENATION
Abstract

The first‐of‐its‐kind, one‐pot N‐alkylation reaction of amines over Ni(II) impregnated porous organic polymer of highly dense N‐rich skeleton is reported. The primeval Ni(II) decorated hollow spherical porous polymer is synthesized and employed in a series of catalytic reactions involving C−N bond formation. The catalytic reactions are optimised to yield the desired product highlighting the role of different substituents present on the reactants towards the overall selectivity and efficiency. The detailed reaction mechanism is corroborated with computation validating a three‐step arrow formalism viz. dehydrogenation of the alcohol, condensation with amines to generate the imine as intermediate followed by hydrogenation by a borrowing strategy to yield the final product. The role of the bare support material in the first step and that of the Ni(II) centres of the support material in the third step is marked as pivotal for the forward reaction to proceed with enriching sustainability and feasibility. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Oxidation pathways and kinetics of the 1,1,2,3-tetrafluoropropene (CF2＝CF–CH2F) reaction with Cl-atoms and subsequent aerial degradation of its product radicals in the presence of NO.

Author

Kakati, Udeshna Priya, Dowerah, Dikshita, Deka, Ramesh Chandra, Gour, Nand Kishor, and Paul, Subrata

Abstract

To give a comprehensive account of the environmental acceptability of 1,1,2,3-tetrafluoropropene (CF2＝CF–CH2F) in the troposphere, we have examined the oxidation reaction pathways and kinetics of CF2＝CF–CH2F initiated by Cl-atoms using the second-order Møller–Plesset perturbation (MP2) theory along with the 6-31+G(d,p) basis set. We also performed single-point energy calculations to further refine the energies at the CCSD(T) level along with the basis sets 6-31+G(d,p) and 6-311++G(d,p). The estimation of the relative energies and thermodynamic parameters of the CF2＝CF–CH2F + Cl reaction clearly shows that Cl-atom addition reaction pathways are more dominant compared to H-abstraction reaction pathways. The value of the rate coefficient for each reaction channel is calculated using the conventional transition state theory (TST) over the temperature range of 200–1000 K at 1 atm. The estimated overall rate coefficients for the title reaction are found to be 1.10 × 10−12, 1.21 × 10−10, and 1.13 × 10−8 cm3 per molecule per s via the respective calculation methods viz. MP2/6-31+G(d,p), CCSD(T)//MP2/6-31+G(d,p), and CCSD(T)/6-311++G(d,p)//MP2/6-31+G(d,p), at 298.15 K. Moreover, the calculated rate coefficients and percentage branching ratio values suggest that the Cl-atom addition reaction at the β-carbon atom is more preferable to that of the α-carbon addition to CF2＝CF–CH2F. Based on the rate coefficient values calculated by the three different methods, the atmospheric lifetime for the title reaction at 298.15 K is estimated. The radiative efficiency (RE) and Global Warming Potential (GWP) results of the title molecule show that its GWP would be negligible. Further, we have explored the degradation of its product radicals in the presence of O2 and NO. From the degradation results, we have found that CF2(Cl)COF, FCOCH2F, FCFO and FCOCl are formed as stable end products along with various radicals such as ˙CF2Cl and ˙CH2F. Therefore, these findings of kinetic and mechanistic data can be applied to the development and implementation of a novel CFC replacement. [ABSTRACT FROM AUTHOR]

Published
2024
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34. Partial Oxidation of Methane to Methanol by Using Molecular O2 on Pd2+ Catalyst: An Insight from Theory.

Author

Dutta, Priyanka, Biswakarma, Nishant, Dowerah, Dikshita, Neog, Shilpa, Islam, Saiful, Sarma, Srutishree, Basumatary, Moumita, Churi, Partha Pratim, Sarma, Plaban Jyoti, Gour, Nand Kishor, and Deka, Ramesh Chandra

Subjects
PARTIAL oxidation, OXIDATION of methanol, POTENTIAL energy surfaces, ATOMIC orbitals, DENSITY functional theory, METHANE as fuel, METHANOL
Abstract

The partial oxidation of methane to methanol using cationic Pd2 dimers is investigated by employing density functional theory (DFT) method. We used B3PW91 functional for geometry optimization, and frequency calculations of all species involved in [Pd2]++O2+2CH4 reaction. Furthermore, a density‐fitting triple zeta valence with single‐polarization (def2TZVP) is used in the calculation to determine the atomic orbitals of the atoms. We oxidized Pd2+ to [Pd2O2]+ using O2 and performed possible partial oxidation of methane to methanol on [Pd2O2]+ and [Pd2O]+ and explored various intermediates and transition states on the potential energy surface (PES) diagram. From Potential Energy Surface (PES) analysis, it is found that the [Pd2O2]+ in doublet spin state multiplicity (SM=2) following radical mechanism is the more preferred pathway for methane to methanol conversion. [ABSTRACT FROM AUTHOR]

Published
2023
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