Reena Goyal

Oxidative coupling of aniline and desulfurization over nitrogen rich mesoporous carbon

Tungsten loaded mesoporous nitrogen rich carbon (WOxMCNx) materials were synthesized using SBA-15 as a hard template. With these new multifunctional materials, we performed a one-pot oxidative coupling of aniline to azo-benzene followed by desulfurization of dibenzothiophene (DBT) to dibenzothiophene sulfone (DBTSO). It was observed that the nature of the support for the catalyst has a strong influence on the activity of the WOx nanoparticle. Whilst WOx on MCNx proved to be a very active and selective catalyst for the formation of azo-benzene via oxidation of aniline as well as dibenzothiophene sulfone from dibenzothiophene, WOx on activated carbon or SBA-15 did not show comparable activity. These multifunctional hybrid catalysts retain their structural framework even after the reaction, and they were recovered easily from the reaction mixture through filtration and reused several times without a significant degradation in activity. Moreover, there was no contribution from leached active species in the activity and conversion was possible only in the presence of the multifunctional catalyst.

Acid–Base Cooperative Catalysis over Mesoporous Nitrogen‐Rich Carbon

WOx nanoclusters (2–3u2005nm) embedded on a mesoporous nitrogen‐rich carbon material were synthesized by using novel methodology. This material was very effectively capitalized as a new carbon‐based acid–base cooperative catalyst for sequential acetal hydrolysis and Knoevenagel condensation reactions. The protocol was also explored for the nitroaldol condensation reaction.

Single-step synthesis of hierarchical BxCN: a metal-free catalyst for low-temperature oxidative dehydrogenation of propane

A boron- and nitrogen-co-doped mesoporous carbon (BxCN) material with a hierarchical pore structure has been synthesized from a new boron precursor via a nanocasting approach. The newly synthesized material was thoroughly characterized by different characterization techniques. It was observed that the BxCN material has an excellent specific surface area, versatile pore diameter and large pore volume. Moreover, the pore diameter can be tuned by varying the amount of the boron source. By using solid-state MAS NMR and XPS, we demonstrated the N–B–C-type structure of the material. The material presented here has excellent stability under an oxygen atmosphere and we also confirmed the catalytic proficiency of this newly developed material in C–H bond activation reactions. The mesoporous BxCN material displays promising catalytic activity for the oxidative dehydrogenation of propane (6.7%) with excellent selectivity for propylene (84.6%) without the presence of any metal.

Hydrogenation of 5-hydroxymethylfurfural to 2,5 dimethylfuran over nickel supported tungsten oxide nanostructured catalyst

2,5 Dimethylfuran (DMF) can be considered as a promising new generation alternative fuel, which has the potential to solve the fossil fuel shortage and also the ongoing global warming issues. Although there are several reports in the literature on the production of DMF from 5-hydroxymethylfurfural, in most of the cases, the operating pressure is very high and expensive metals, such as Pd, Pt, and Rh, have been used in the presence of organic solvents. Herein, we report the preparation of nickel oxide nanoparticles supported on nanostructured tungsten oxide and the use of this catalyst as a heterogeneous catalyst for the selective hydrogenation of the biomass-derived platform molecule 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF), a liquid fuel, at 10 bar H2 pressure and 180 °C temperature in an aqueous medium. The catalyst was characterized using XRD, TEM, SEM, XPS, Raman and FTIR spectroscopies, TGA, and ICP-AES techniques. The catalyst showed >99% conversion of HMF with 95% selectivity of DMF without the use of any additives under optimized reaction conditions. The effect of reaction parameters, such as temperature, pressure of H2, and the loadings of Ni, was investigated and has been discussed in detail. The reusability of the catalyst was tested by conducting repeat experiments with the spent catalyst, where it was found that the catalyst displayed no changes in its activity and selectivity even after 5 successive runs. Based on the experimental results, a possible reaction pathway has been proposed.

Synthesis of AgWCN x Nanocomposites for the One-Step Conversion of Cyclohexene to Adipic Acid and Its Mechanistic Studies

A novel catalyst composed of silver nanoparticles grafted on WCNx has been prepared by using a facile pH-adjusted method. The material reported in this study presents a non-mineral acid route for the synthesis of the industrially significant monomer adipic acid through the selective oxidation of cyclohexene. Ag has been stabilized in the hydrophobic matrix during the formation of the mesoporous silica material by using aniline as stabilizing agent. A cyclohexene conversion of 92.2u2009% with 96.2u2009% selectivity for adipic acid was observed with the AgWCNx -2 catalyst, therefore, the AgWCNx catalyst was found to be efficient for the direct conversion to adipic acid with respect to their monometallic counterparts. The energy profile diagrams for each reaction path by using the AgWCNx catalyst were studied along with their monometallic counterparts by using the Gaussianu200509 package. The reported material can avoid the use of harmful phase-transfer catalysts (PTC) and/or chlorinated additives, which are two among other benefits of the reported work.