Raghuvir Singh

Halogen-free imidazolium/ammonium-bis(salicylato)borate ionic liquids as high performance lubricant additives

Halogen-free bis(salicylato)borate anion based ionic liquids having imidazolium and ammonium cations, were designed, synthesized, characterized and then evaluated as potential lubricant additives. Owing to the high polarity, high London dispersive forces and high rigidity associated with the bulk size and ring structure of the bis(salicylato)borate anion, these ionic liquids possess very high viscosities. The interaction of these ionic liquids with contact surfaces has been found to be strongly influenced by the van der Waals interactions in the ionic liquids, which increases with an increase of the alkyl chain length, particularly, for the imidazolium cations. As lubricant additives, both imidazolium and ammonium ionic liquids markedly improve the friction-reducing and anti-wear properties of PEG 200 lube base. Microstructural images and element mapping of the worn surfaces of steel balls reveal that these ionic liquids form tribo-films, which reduces both the friction and wear. Being halogen-, phosphorus-, and sulfur-free, bis(salicylato)borate ionic liquids not only protect contact surfaces from tribo-corrosive events but also keep the environment green and clean. These ionic liquids offer an environmentally friendly alternative to conventional halogenated ionic liquids being currently developed for lubricant applications.

Value addition to rice straw through pyrolysis in hydrogen and nitrogen environments

Pyrolysis of rice straw has been carried out under hydrogen atmosphere at 300, 350, 400 and 450 °C and pressures of 1, 10, 20, 30 and 40 bar and in nitrogen atmosphere, experiments have been carried out at the same temperatures. It has been observed that the optimum process conditions for hydropyrolysis are 400 °C and 30 bar pressure and for slow pyrolysis, the optimum temperature is 400 °C. The bio-oil has been characterised using GC-MS, (1)H NMR and FT-IR and bio-char using FT-IR, SEM and XRD. The bio-oil yield under hydrogen pressure was observed to be 12.8 wt.% (400 °C and 30 bar) and yield under nitrogen atmosphere was found to be 31 wt.% (400 °C). From the product characterisation, it was found that the distribution of products is different for hydrogen and nitrogen environments due to differences in the decomposition reaction mechanism.

Thiourea dioxide with TBHP: a fruitful and greener recipe for the catalytic oxidation of alcohols

Thiourea dioxide, owing to its hydrogen bonding ability, has been established as an exceptional, widely applicable organocatalyst. In the present paper, thiourea dioxide, an organocatalyst, in combination with t-butyl hydroperoxide (TBHP), a non-toxic and environmentally benign oxidant, serves to be a greener and more fruitful approach for the oxidation of alcohols to corresponding carbonyl compounds in excellent yields under mild reaction conditions.

Heterostructured nanocomposite tin phthalocyanine@mesoporous ceria (SnPc@CeO2) for photoreduction of CO2 in visible light

Heterostructured tin phthalocyanine supported to mesoporous ceria was synthesized and used a photocatalyst for CO2 reduction under visible light. The photoreduction CO2 activities of the heterostructures were investigated in the presence of triethylamine as sacrificial agent. The developed photocatalyst exhibited high catalytic activity for photoreduction of CO2 and after 24 hours of visible light irradiation 2342 μmol g−1 cat of methanol (ϕMeOH = 0.0223 or 2.23%) and 840 μmol g−1 cat of CO (ϕCO = 0.0026 or 0.26%) were obtained as the major reaction products. The methanol formation rate (RMeOH) and CO formation rate (RCO) was found to be 97.5 μmol h−1 g−1 cat and 35.0 μmol h−1 g−1 cat respectively. While under the identical experimental conditions mesoporous ceria (meso-CeO2) gave only 316 μmol g−1 cat of methanol (ϕMeOH = 0.003 or 0.30%) and 126 μmol g−1 cat CO (ϕCO = 0.0004 or 0.04%) with product formation rate RMeOH = 13.2 μmol h−1 g−1 cat and RCO = 5.3 μmol h−1 g−1 cat. Furthermore, the recovered catalyst showed consistent catalytic activity for at least five runs without any significant loss in product yields.

Experimental study on the efficacy of MoS2 microfluids for improved tribological performance

This paper reports the synthesis and tribo-performance investigation of microfluids developed using silane functionalized µ-molybdenum disulphide (µ-MoS2) particles for improved tribological performance. The functionalized µ-MoS2 particles were characterized by analytical techniques like Fourier-transform infrared, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The µ-MoS2 particles were then blended with mineral base oil in varying concentrations. The lubrication characteristics in terms of anti-friction, anti-wear, and extreme pressure properties of the µ-MoS2 particle blended microfluids were evaluated under different lubrication regimes. The results showed an excellent improvement in anti-wear, anti-friction, and extreme pressure properties. The tribo-performance of the MoS2 microfluids strongly depends on the compatibility and concentration of particles with base oils. Functionalization of the µ-MoS2 particles by trichlorooctadecylsilane allows forming stable dispersion in base oil. The MoS2 microfluids can be used as lubricants in advance tribological applications.

Magnetically separable chicken feathers: a biopolymer based heterogeneous catalyst for the oxidation of organic substrates

Magnetically separable poultry chicken feathers were found to be an efficient, green and heterogeneous catalyst for the oxidation of alcohols and sulfides to the corresponding carbonyl compounds and sulfoxides, respectively using t-butyl hydroperoxide (TBHP) as oxidant with complete selectivity and high conversions. The developed catalyst exhibited higher stability, activity and better recycling ability than the bare magnetic nanoparticles. The designed catalyst could readily be recovered using an external magnet without showing any significant leaching during the reaction.

Oxidation of Cyclohexane Over Nanoclusters of Cu (II) Supported on Nanocrystalline Tungsten Oxide with H2O2 as Oxidant

A facile hydrothermal synthesis method is developed for the preparation of Cu (II) nanoclusters (with average particle size 6 nm) supported on nanocrystalline tungsten (VI) oxide. Detailed characterization of the material was carried out by XRD, SEM, TEM, ICP-AES and TGA. The catalyst was highly active for selective oxidation of cyclohexane to adipic acid with H2O2. The reusability of the catalyst was tested by conducting same experiments with the spent catalyst and it was found that the catalyst did not show any significant activity loss even after 5 reuses. A cyclohexane conversion of 62.5 % with 27 % adipic acid selectivity was achieved over this catalyst at room temperature