Palladium nanoparticles supported on mesoporous natural phosphate: An efficient recyclable catalyst for nitroarene reduction

We report the preparation of palladium nanoparticles supported on mesoporous natural phosphate (Pd@NP) using a wetness impregnation method. The prepared catalyst was characterized using various techniques. Furthermore, the reduction and preparation of the palladium nanoparticles was followed using UV–visible spectra. Based on the Scherrer equation, the crystallite size of the as‐synthesized palladium nanoparticles was 10.88 nm. The performance of the synthesized catalyst was investigated in the reduction of 4‐nitrophenol as a model substrate to 4‐aminophenol using NaBH₄ as a hydrogen source. Moreover, catalytic reduction of various nitroarenes was studied and monitored using UV–visible spectroscopy and gas chromatography. The Pd@NP catalyst showed a high activity for the selected reaction and could be recycled.     

Phosphate of Zirconium as a Reusable Efficient Catalyst for the Synthesis of 2-Arylquinazolin-4(3H)-ones

Kinetics and Catalysis - Our work is around the heterogeneous catalysts based on phosphate. This is all the more important as Morocco has a significant wealth of world reserves of this mineral....     

Assessment of Corrosion Inhibition Performance and Adsorption Thermodynamics of Hydrogen Phosphate (HPO42−) and Molybdate (MoO42−) Oxyanions on Tin in Maleic Acid

The influence of hydrogen phosphate (HPO₄²⁻) and molybdate ions (MoO₄²⁻) on the behavior of tin corrosion in 0.2 M maleic acid was compared using experimental and theoretical techniques. The experimental studies consisted of the electrochemical investigations (potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)), along with the surface analytical techniques (SEM and EDX). Additionally, the theoretical analysis (the chemical quantum computations at MP4/SDD level of theory in the aqueous phase), was conducted. The experimental outcomes illustrated that the inhibition efficiency (η%) increases with the concentration of the inhibitors, reaching 88 % and 81 % at 2×10⁻² M concentration of MoO₄²⁻ and HPO₄²⁻, respectively. The potentiodynamic polarization curves revealed that HPO₄²⁻ performance is a cathodic-type inhibitor, while MoO₄²⁻ shows a mixed-type behavior. The increase in temperature decreased the η% values of both inhibitors. Based on surface analysis and thermodynamic study, the presence of the two inhibitors formed protective films on the tin surface through a physisorption mechanism. The chemical quantum computations using the complete fourth-order Møller Plesset perturbation theory (MP4 with SDD basis) method results outlined the favorable affinity of the investigated inorganic inhibitors to interact with the tin surface, which interprets the well-observed inhibition efficiencies.     

Cellulose based electrospun nanofilters: perspectives on tannery effluent waste water treatment

Cellulose - Development of nanofilters with the ability to remove toxic metal ions from effluent wastewater will be of immense help to the leather industry. In this study, fibrous nanofilter (FNF)...     

On some q-versions of the Ramanujan Master Theorem

The Ramanujan Journal - In this paper, we state some q-analogs of the famous Ramanujan Master Theorem. As an application, we compute some values of Jackson’s q-integrals that involve...     

Identifying the Role of Brønsted and Lewis Acid Sites in the Diels-Alder Cycloaddition of 2,5-DMF and Ethylene

The role of Lewis and Brønsted acid sites in the Diels-Alder cycloaddition (DAC) of ethylene to 2,5-dimethylfuran (2,5-DMF) to p-xylene was investigated. Amorphous silica catalysts containing Al³⁺ (ASA), Ga³⁺ (ASG), and In³⁺ (ASI) were prepared via homogeneous deposition-precipitation. Silica modified with Zr⁴⁺ (ASZ) was prepared by impregnation. Their acidic properties were characterized by various IR and NMR spectroscopic techniques. Measurements using pyridine as a probe molecule highlighted the presence of mostly Lewis acid sites (LAS) in all materials. Using CO as a probe, in contrast, demonstrated the existence of Brønsted acid sites (BAS) in ASA and ASG, which were nearly absent in ASI and ASZ. Differences in basic strength can explain the contrast in results observed between the two probe molecules. The highest p-xylene yield (~20 %) in the DAC reaction, could be achieved with ASA and ASG. The lack of BAS in ASI and ASZ resulted in inferior performance in the DAC, with p-xylene yields below 5 %. These results indicate the importance of BAS for the DAC reaction. Several other heterogeneous and homogeneous catalysts were explored for the DAC reaction to show the generality of our conclusion that BAS play a critical role in obtaining p-xylene from 2,5-DMF and ethylene.