Catalytic synergy: N,P modification of activated carbon for improved 1-chloro-4-nitrobenzene reduction

Carbon materials have emerged as a new generation of catalysts for the crucial industrial hydrogenation of nitroarenes. Activated carbon, known for its cost-effectiveness and facile modifiability, stands out among various carbon materials. This study focuses on the preparation of N and P co-doped carbons for catalysing the hydrogenation of 1-chloro-4-nitrobenzene. Comprehensive characterisation using thermal analysis (TGA-MS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N2 adsorption at -196 ºC, and ICP-MS was performed. The synergistic effect of N and P was evident, with co-doped carbons outperforming their mono-doped counterparts, underscoring the significance of nitrogen. N,P-codoped activated carbon emerges as a promising, active, stable, and selective metal-free catalyst for the hydrogenation of 1-chloro-4-nitrobenzene, leading to 4-chloroaniline.The authors gratefully acknowledge the financial support provided by the Ministerio de Ciencia e Innovación (Spain) under Project PID2019-108453GB-C21. ESDU also thanks the Generalitat Valenciana for their support through grant GRISOLIAP/2020/123. Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital (CIPROM/2021/022)

Unlocking catalytic potential: Harnessing the power of oxidized active carbons for the hydrogenation of 1-chloro-4-nitrobenzene

This study explores the effects of liquid-phase and gas-phase oxidation treatments on a low-ash activated carbon (RGC30) and its subsequent use as a metal-free catalyst for the hydrogenation of 1-chloro-4-nitrobenzene. Characterisation of the catalysts was accomplished through N2 and CO2 adsorption at −196 °C and 0 °C, respectively, together with techniques like X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric analysis (TGA) and temperature-programmed desorption (TPD). In particular, it is observed that the catalytic activity depends on the specific oxidation treatment applied, which leads to the generation of different oxygenated groups on the carbon surface. Consequently, through precise control of oxygen groups via thermal treatment under inert conditions, it is found that the most influential groups for the hydrogenation of 1-chloro-4-nitrobenzene are basic groups incorporating Cdouble bondO bonds, such as quinones and carbonyls. Furthermore, certain groups, like phenols, exhibit a detrimental impact on the catalytic activity.Financial support from Ministerio de Ciencia e Innovación (Spain, project PID1019-108453GB-C21 and PID2020-116998RB-I00) is gratefully acknowledged. ESDU also thanks Consellería de Innovación, Universidaddes Ciancia y Sociedad Digital (Generalitat Valenciana, Spain) for his GRISOLIAP/2020/123 grant and CIPROM/2021/022. This study forms part of the Advanced Materials programme and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Generalitat Valenciana

Highly efficient nickel-niobia composite catalysts for hydrogenation of CO2 to methane

We studied the catalytic hydrogenation of CO2 to methane using nickel-niobia composite catalysts. Catalysts containing 10–70 wt% Ni were synthesized by wet impregnation and tested for CO2 hydrogenation in a flow reactor. 40 wt% was found to be the optimum Ni loading, which resulted in CO2 conversion of 81% at 325 °C. We also calcined the Nb2O5 support at different temperatures to study the influence of calcination temperature on the catalytic performance. 40 wt% Ni loaded on Nb2O5, which was calcined at 700 °C gave higher methanation activity (91% conversion of CO2). Time on stream study for 50 h showed a stable activity and selectivity; thus confirming the scope for practical application.E.S.G. and N.R.S acknowledge the financial support from NOW CAPITA project (732.013.002). ASE acknowledges the financial support from the MINECO projects MAT-2013-45008-P and MAT2016-81732-ERC. EVRF gratefully acknowledge support from MINECO for his Ramón y Cajal grant (RyC-2012-11427) and University of Alicante for the project GRE-13-31. Generalitat Valenciana is also acknowledged for financial support (PROMETEOII/ 2014/004)

Quark-hadron duality, axial anomaly and mixing

Interplay between axial anomaly and quark-hadron duality in the presence of strong mixing is considered. The anomaly sum rule for meson transition form factors based on the dispersive representation of axial anomaly and quark-hadron duality in octet channel is analyzed. The comparison of this sum rule to the experimental data on $\eta$ and $\eta'$ mesons transition form factors shows that the interval of duality in this channel is rather small, contradicting the usual understanding of quark-hadron duality. The same values of interval of duality are supported by considering the two-point correlator in the local duality limit. This contradiction may be resolved by introducing of some nonperturbative non-OPE correction to the relevant spectral density. The form and value of this correction are discussed.Comment: 9 pages, 1 figure, reference adde

Large Electric Dipole Moments of Heavy Leptons

In many models of CP violation, the electric dipole moments (EDMs) of leptons scale as the cube of the lepton mass. In these models, the EDM of a 100 GeV heavy lepton would be a billion times greater than that of the muon, and could be as large as a 0.01 e-fermi. In other models, in which the heavy leptons have different properties from the lighter generations, a similarly large EDM can be obtained. A large EDM could dominate the electromagnetic properties of heavy leptons. The angular distribution and production cross-section of both charged and neutral heavy leptons with large dipole moments is calculated and discussed. The interesting possibility that a heavy neutrino with a large EDM could leave an ionization track in a drift chamber is investigated.Comment: Discussion expanded extensively to include model-dependence of results. Calculations unchanged. Note Added To Acknowledgments: This paper is dedicated to the memory of Nathan Isgu

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti2AlC MAX Phase

MAX (M(n+1)AX(n)) phases are layered carbides or nitrides with a high thermal and mechanical bulk stability. Recently, it was shown that their surface structure can be modified to form a thin non-stoichiometric oxide layer, which can catalyze the oxidative dehydrogenation of butane. Here, the use of a Ti2AlC MAX phase as a support for cobalt oxide was explored for the dry reforming of butane with CO2, comparing this new catalyst to more traditional materials. The catalyst was active and selective to synthesis gas. Although the surface structure changed during the reaction, the activity remained stable. Under the same conditions, a titania-supported cobalt oxide catalyst gave low activity and stability due to the agglomeration of cobalt oxide particles. The Co3O4/Al(2)O(3)catalyst was active, but the acidic surface led to a faster deactivation. The less acidic surface of the Ti2AlC was better at inhibiting coke formation. Thanks to their thermal stability and acid-base properties, MAX phases are promising supports for CO(2)conversion reactions

Top-Charm Associated Production in High Energy e+e−e^+e^- Collisions

The possibility of exploring the flavor changing neutral current $tcZ/tc\gamma$ couplings in the production vertex for the reaction \epem\to t\bar c + \bar tc is examined. Using a model independent parameterization for the effective Lagrangian to describe the most general three-point interactions, production cross sections are found to be relatively small at LEP II, but potentially sizeable at higher energy \epem colliders. The kinematic characteristics of the signal are studied and a set of cuts are devised for clean separation of the signal from background. The resulting sensitivity to anomalous flavor changing couplings at LEP II with an integrated luminosity of $4\times 500$ pb$^{-1}$ is found to be comparable to their present indirect constraints from loop processes, while at higher energy colliders with $0.5-1$ TeV center-of-mass energy and 50-200 fb$^{-1}$ luminosity, one expects to reach a sensitivity at or below the percentage level.Comment: Latex, 22 page

Structural and Luminescence Properties of Silica-Based Hybrids Containing New Silylated-Diketonato Europium(III) Complex

A new betadiketonate ligand displaying a trimethoxysilyl group as grafting function and a diketone moiety as complexing site (TTA-Si = 4,4,4-trifluoro-2-(3-trimethoxysilyl)propyl)-1-3-butanedione (C4H3S)COCH[(CH2)3Si(OCH3)3]COCF3) and its highly luminescent europium(III) complex [Eu(TTA-Si)3] have been synthesized and fully characterized. Luminescent silica-based hybrids have been prepared as well with this new complex grafted on the surface of dense silica nanoparticles (28 (+/-3 nm) or on mesoporous silica particles. The covalent bonding of Eu(TTA-Si)3 inside the core of uniform silica nanoparticles (40 (+/- 5 nm) was also achieved. Luminescence properties are discussed in relation to the europium chemical environment involved in each of the three hybrids. The general methodology proposed allowed high grafting ratios and overcame chelate release and tendency to agglomeration, and it could be applied to any silica matrix (in the core or at the surface, nanosized or not, dense or mesoporous) and therefore numerous applications such as luminescent markers and luminophors could be foreseen

Electromagnetic transitions in an effective chiral Lagrangian with the eta-prime and light vector mesons

We consider the chiral Lagrangian with a nonet of Goldstone bosons and a nonet of light vector mesons. The mixing between the pseudoscalar mesons eta and eta-prime is taken into account. A novel counting scheme is suggested that is based on hadrogenesis, which conjectures a mass gap in the meson spectrum of QCD in the limit of a large number of colors. Such a mass gap would justify to consider the vector mesons and the eta-prime meson as light degrees of freedom. The complete leading order Lagrangian is constructed and discussed. As a first application it is tested against electromagnetic transitions of light vector mesons to pseudoscalar mesons. Our parameters are determined by the experimental data on photon decays of the omega, phi and eta-prime meson. In terms of such parameters we predict the corresponding decays into virtual photons with either dielectrons or dimuons in the final state.Comment: 17 pages, extended discussion on mixin