BITS Faculty Publications

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    Sustainable valorization of macroalgae residual biomass, optimization of pyrolysis parameters and life cycle assessment
    (Elsevier, 2024-04) Sangwan, Kuldip Singh; Raghuvanshi, Smita
    The major challenges for the current climate change issue are an increase in global energy demand, a limited supply of fossil fuels, and increasing carbon footprints from fossil fuels, which have necessitated the exploration of sustainable alternatives to fossil fuels. Biorefineries offer a promising path to sustainable fuel production, converting biomass into biofuels using diverse technologies. Aquatic biomass, such as macroalgae in this context, represents an abundant and renewable biomass resource that can be cultivated from water bodies without competing with traditional agricultural land. Despite this, the potential of macroalgae for biofuel production remains largely untapped, with very limited studies addressing their viability and efficiency. This study investigates the efficient conversion of unexplored macroalgae biomass through a biorefinery process that involves lipid extraction to produce biodiesel, along with the production of biochar and bio-oil from the pyrolysis of residual biomass. To improve the effectiveness and overall performance of the pyrolysis system, Response Surface Methodology (RSM) was utilized through a Box-Behnken design to systematically investigate how alterations in temperature, reaction time, and catalyst concentration influence the production of bio-oil and biochar to maximize their yields. The results showed the highest bio-oil yield achieved to be 36 %, while the highest biochar yield reached 45 %.
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    Microwave-Assisted Synthesis of Azoniaspiro Compounds Using a Novel Catalyst, 1-Azaphenothiazine
    (Taylor & Francis, 2011) Sakhuja, Rajeev
    Azaphenothiazine catalyses the intramolecular cyclization of N-(bromoalkyl)phthalimides in the presence of anhydrous K2CO3 to form spiro cyclic quaternary ammonium salts, namely azoniaspiro compounds, under microwave irradiation. A novel and ecofriendly method was developed for the synthesis of azoniaspiro compounds, and the role of azaphenothiazine as a catalyst in such reactions has been established for the first time. In the future, this protocol can be extended to the synthesis of various substituted N-heterocycles by hydrolyzing the resulting azoniaspiro compounds.
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    Imidazolium ionic liquid-tagged palladium complex: an efficient catalyst for the Heck and Suzuki reactions in aqueous media
    (RSC, 2014) Kumar, Anil; Sivasubramanian, S.C.; Khungar, Bharti
    An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology
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    Experimental studies of catalyst deactivation due to carbon and sulphur during CO2 reforming of CH4 over Ni washcoated monolith in the presence of H2S
    (Wiley, 2021-07-18) Srinivas, Appari
    This study presents the CO2 reforming of CH4 over Ni coated monolith catalyst at 800°C and 101.325 kPa. The high CH4 to CO2 ratio employed in this study is similar to the CH4:CO2 ratio of >1 found in biogas. Cordierite monolith samples (0.258 channels per m2) washcoated with alumina are used for the experimental purpose. The study considers the combined deactivation effect due to sulphur poisoning and fouling due to carbon deposition. Four different cases with respect to the introduction and removal of H2S are considered. The rate of deactivation due to simultaneous carbon deposition and sulphur poisoning is much faster than the individual poisoning processes. The catalyst shows almost stable operation for 6 h without the presence of urn:x-wiley:00084034:media:cjce24266:cjce24266-math-0001 in the feed stream. From the conversion studies, it appears that the pre-treatment of catalyst samples with H2S leads to negligible sulphur coverage. The sulphur poisoning effect is also found to be reversible.
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    Techniques for Overcoming Sulfur Poisoning of Catalyst Employed in Hydrocarbon Reforming
    (Springer, 2021-08-07) Srinivas, Appari
    Sulfur poisoning of catalyst is a well-known phenomenon observed during the production of syngas (CO + H2). The presence of traces of sulfur content in the feedstock can drastically reduce the catalyst activity and life. Several measures have been developed over the years to mitigate the catalyst deactivation process due to sulfur poisoning. In this paper, we review literature from 1996-present related to all the developments made for sulfur-resistant systems. The basis of poisoning being the sulfur content in the feedstock, potential fuel-containing feedstocks for syngas production were briefly discussed. The basics of sulfur poisoning mechanisms are also summarized. Then, a framework consisting of sulfur tolerance methodologies were discussed. In particular, we have discussed: (i) catalyst development by altering catalyst composition and support systems, (ii) influence of using catalyst structures, (iii) process modifications and optimization, (iv) desulfurization techniques for removal of sulfur from feed and/or product streams, and (v) effective catalyst regeneration techniques to extend the catalyst life. This review emphasizes the integration of the best set of methods to develop sulfur tolerance strategies.
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    Synthesis, characterization and applications of imidazolium ionic liquid-tagged zinc(II) complex
    (Elsiever, 2018) Khungar, Bharti; Nehra, Pankaj; Sivasubramanian, S.C.; Jha, Prabhat N.
    A multi-functional zinc(II) complex of an imidazolium ionic liquid-tagged ligand was synthesized and characterized. The DSC and TGA analysis showed the thermal stability of the complex. The complex showed emission λmax at 368–467 nm with quantum yields up to 0.06. The time-resolved fluorescence study revealed enhancement in lifetime on complexation with zinc(II) ion indicating conformational rigidity. The complex showed good DNA cleavage, antifungal and antibacterial activities against Gram +ve and Gram −ve bacteria. The complex was found to be a good catalyst for the reaction of aromatic aldehydes and indole substrates in water to synthesize bis(indolyl)methanes.