Browsing by Author "Dutta, Saikat"

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Application of Polyoxometalates as Efficient and Green Catalyst for Catalytic Upgrading of Cellulosic Biomass
(National Institute of Technology Karnataka, Surathkal, 2020) Tiwari, Ritesh; Mal, Sib Shankar; Dutta, Saikat
In recent years, the research on the sustainable production of energy, transportation fuels, and materials has been incentivized. Non-food and preferably waste biomass has been identified as a commercially-feasible renewable alternative to fossilized carbons for producing fuels and chemicals. The chemocatalytic value addition of biomass, where the oxygen-rich biopolymers are selectively deconstructed into functionally-rich small organic molecules, is of particular interest. A new generation of robust, inexpensive, and environment-friendly catalysts are crucial for the chemocatalytic route. Over the past years, heteropolyacids (HPAs) are increasingly being used as a catalyst in the chemistry of renewables and biomass value addition. HPAs have been used in the hydrolysis and dehydration of pentose and hexose sugars in biomass into furfural and 5- (hydroxymethyl)furfural (HMF), respectively. Furfural, levulinic acid, and HMF act as renewable chemical building blocks that can be converted into commodity chemicals and materials via chemical or catalytic transformations. The proposed work is intended to explore the efficiency of various homogenous and heterogeneous HPA catalysts for the catalytic upgrading of biomass-derived chemical intermediates into value-added chemicals. HPA-based homogeneous and heterogeneous catalysts were used for the acetalization, esterification, and Baeyer-Villiger oxidation reactions of various biomass-derived chemical intermediates. The reaction conditions were optimized on various parameters such as temperature, duration, loading of reactant, and loading of catalyst. The cyclic acetals of biomass-derived furfural were prepared in high isolated yields in refluxing benzene in the presence of the phosphotungstic acid (PTA) catalyst. The PTA catalyst was successfully recovered and reused several times without significant loss in mass or activity. The esterification of saturated and unsaturated free fatty acids such as oleic acid and stearic acid were conducted in the presence of PTA catalyst as an efficient and recyclable catalyst. 2-Furanone was prepared by the selective oxidation of furfural using hydrogen peroxide as an inexpensive oxidant and PTA supported on ammonium zeolites as the catalyst. A scalable and high yielding preparation of alkyl benzoates and alkyl 2-furoates has also been reported.
Catalytic Preparation and Value Addition of Renewable Chemical Intermediates from Carbohydrates
(National Institute of Technology Karnataka, Surathkal, 2023) Bhat, Navya Subray; Dutta, Saikat; Mal, Sib Sankar
Adopting biomass-derived fuels and chemicals could help to relieve the economic and environmental distresses triggered by the excessive use of petrofuels and petrochemicals. Moreover, the suitable integration of biomass carbon in the chemical industry would be a giant step toward their long-anticipated sustainability. Carbohydrate-derived furfural (FUR), 5-(hydroxymethyl)furfural (HMF), and levulinic acid (LA) have received significant attention over the past three decades as renewable chemical platforms for the synthesis of a variety of biofuels and chemicals of commercial significance. The elegant acid-catalyzed processes allow the selective removal of excess oxygen atoms from the parent sugar molecules in the form of water under energy-efficient conditions. The inherent instability in aqueous acid, hydrophilicity, and poor thermal stability of HMF complicates its isolation from the aqueous/polar reaction media and challenges the scalability of the process. In this regard, the hydrophobic analogs of HMF have received significant interest as the functional equivalent of HMF. 5-(Chloromethyl)furfural has also gained considerable interest as a substitute for HMF and has shown promise as the hydrophobic congener of HMF. Similarly, the esters of HMF, such as 5-(acyloxymethyl)furfural, are particularly interesting since they are halogen-free, hydrolytically stable, and hydrophobic analogs of HMF. The functionalities present in platform molecules are exploited for selective synthetic transformations, preferably under catalytic conditions, to make products of desired structural and functional characteristics. For example, the Baeyer-Villiger oxidation of furanics, especially FUR to 2-furanone, remains largely underexplored. The catalytic esterification or transesterification of biomass-derived intermediates will lead to corresponding esters with potential applications as green solvents, novel oxygenates, plasticizers, surfactants, and chemical reagents. Carbohydrate-derived renewable chemicals are of academic and commercial interest. Even incremental improvement in their yields and simplification of the processes for their production will significantly benefit this area of research.
Co-pyrolysis of scrap tire and plastic using coal derived fly-ash
(2019) Mohan, A.; Dutta, Saikat; Madav, V.; Bhushnoor, S.S.; Garcia, J.F.; Williams, P.T.
Used automobile tires and thermoplastics (e.g. polypropylene) have become liability of modern societies and several avenues have been explored for their suitable disposal. Pyrolytic liquefaction of tires and plastics have attracted significant attention since the process can provide value-added products such as liquid transportation fuels and chemicals while mitigating the waste disposal issues. Pyrolysis can be done both in absence (thermal) or presence (catalytic) of a catalyst. Catalytic pyrolysis is favored by less demanding reaction conditions and better quality of product. Catalytic copyrolysis has the additional advantage in using a wider feedstock and a possible synergistic effects from different feeds during molecular transformations. This work investigates the effect of untreated fly-ash (class F) as catalyst for the copyrolysis of scrap tire and polypropylene at 300o C and atmospheric pressure using batch type pyrolysis reactor and also studied the effect of fly-ash during pyrolysis of scrap tire using Pyro-GC/MS. Copyrolysis was carried out using various ratio of scrap tire and polypropylene at 300o C, whereas the pyrolysis of scrap tire in pyro-GC/MS was carried out at 500o C. The maximum yield (23.33%) of oil was obtained at a ratio of 60:40 (w/w) of scrap tire and polypropylene in presence of 20wt% of fly ash catalyst. The oils were characterized by NMR, GC-MS, FT-IR and elemental analysis. � 2019 ETA-Florence Renewable Energies.
Energy Densification of Carbohydrate-Derived Chemical Platforms by Catalytic Hydrogenation and Esterification Reactions
(National Institute of Technology Karnataka, Surathkal, 2024) Vinod, Nivedha; Dutta, Saikat
Biomass-derived abundant and non-food polymeric carbohydrates (e.g., cellulose) have been identified as suitable biogenic carbon to synthesize transportation fuels, organic chemicals, and polymers. Catalysis remains at the heart of biorefinery research, which ensures energy efficiency, affords high product selectivity and yield, lessens materials input, and minimizes waste generation. The acid-catalyzed hydrolysis and dehydration of heavily functionalized and oxygenated biopolymers like cellulose into 5- (hydroxymethyl)furfural (HMF) is an elegant chemocatalytic value addition pathway of biomass. Other carbohydrate-derived compounds formed under acid hydrolysis conditions include furfural (FF) and levulinic acid (LA). Isosorbide (IS) can be formed from cellulose by catalytic steps involving hydrolysis, hydrogenation, and dehydration reactions. HMF, FF, LA, and IS have been identified as renewable chemical platforms for synthesizing wide classes of compounds of commercial significance. The value addition pathways often involve removing oxygen atoms and adding more hydrogen and carbon atoms in the structure for higher energy density. Humin, a complicated furan-based polymer, is formed as a side product during the acid-catalyzed dehydration of carbohydrates. Significant research has focused on minimizing humin formation and developing value-addition pathways of this waste material. This work developed solid acid and noble metal-based catalysts supported on humin-derived activated carbon (HAC) for the synthetic value addition of FF, HMF, and LA. γ-Butyrolactone (GBL) and γ-valerolactone (GVL), with potential applications as fuel oxygenates and green solvents, have been produced by catalytic hydrogenation of their precursors (i.e., 2- furanone and angelica lactone) using the Pd/HAC catalyst. Ethyl levulinate (EL), a potential diesel additive, has been produced by the esterification of LA and ethanolysis of furfuryl alcohol, respectively, using phosphotungstic acid supported on HAC. Various mono- and diesters of IS, with potential applications as renewable surfactants and plasticizers, have been reported using the transesterification reaction in the presence of an anhydrous K2CO3 catalyst. All the catalysts and the synthesized products were characterized extensively.
Production of 5 - (Halomethyl) Furfurals from Cellulosic Biomass and their Synthetic Upgrading into Renewable Chemicals
(National Institute of Technology Karnataka, Surathkal, 2020) Sharath, B. O.; Dutta, Saikat
The transportation fuels and most of the bulk and fine chemicals are primarily sourced from crude oil. However, the excessive use of crude oil has depleted the reserves, created a disparity between the demand and supply, and degraded the environment. In search of a renewable and preferably carbon-neutral source, biomass has found by many as a commercially-feasible replacement for fossilized carbon. The chemocatalytic valorization of biomass is of particular interest since they are fast, biomass agnostic, selective, and can potentially be integrated into the existing infrastructure. A major challenge in the chemocatalytic value addition of biomass is to develop a new generation of robust, selective, inexpensive, and environment-friendly catalysts that can selectively deconstruct the biopolymers. In this regard, the acidcatalyzed depolymerization and dehydration of biomass-derived carbohydrates (e.g., cellulose) into furanics is an elegant way of removing excessive functionalities from the carbohydrate. Biomass-derived 5-(hydroxymethyl)furfural (HMF), 5- (chloromethyl)furfural (CMF), furfural and levulinic acid (LA) have been used as renewable chemical building blocks for further value addition into fuels and specialty chemicals. In this thesis work, an improved synthesis of CMF and LA have been reported using aqueous HCl as the acid catalyst in the presence of quaternary ammonium chloride as a surface-active agent (SAA). The SAA afforded noticeably higher yields of CMF and LA compared to the control reactions. The reactions were optimized on various reaction parameters such as temperature, duration, loading of the substrate, and the loading of SAA. The SAA was successfully recovered and recycled. LA was converted into alkyl levulinates, a potential diesel additive and a renewable solvent, in the presence of phosphotungstic acid as an environment-friendly and recyclable catalyst. Alkyl levulinates were also prepared by the alcoholysis of CMF and furfuryl alcohol using HClO4-SiO2 as an inexpensive heterogeneous catalyst. A scalable and high-yielding preparation of 5-(alkoxymethyl)furfural, a novel fuel oxygenate, from CMF has also been reported.
Straightforward synthesis of calcium levulinate from biomass-derived levulinic acid and calcium carbonate in egg-shells
(2019) Sharath, B.O.; Tiwari, R.; Mal, S.S.; Dutta, Saikat
Calcium levulinate (CL) is a nutritional supplement for calcium and a chemical intermediate in synthesizing levulinic biofuels. The reported synthesis of CL involve reaction between cellulose-derived levulinic acid (LA) and calcium hydroxide in an aqueous medium. In this work, we report the production of CL using CaCO3 from poultry egg shells. The scalable production uses biomass-derived LA and egg-shell derived CaCO3 under conventional heating and mechanical stirring. The reaction was optimized on temperature, duration of reaction, and equivalent of CaCO3. Using 1.5 equivalent of CaCO3, the reaction completed within 2h at 50�C and afforded up to 97% isolated yield of CL as a crystalline solid. The reaction was also successfully carried out under mechanical grinding and scaled up to 20 g. The purity of the product was confirmed by melting point, FTIR, 1H-NMR and 13C-NMR spectroscopy. � 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Advanced Materials, Energy & Environmental Sustainability, ICAMEES2018
Synthesis of High-Value Chemicals and Materials from Renewable Resources
(National Institute of Technology Karnataka, Surathkal, 2023) Anchan, Harshitha N.; Dutta, Saikat
Over the past three decades, significant research has been focused on producing fuels and chemicals from renewable carbon resources to reduce the carbon footprint and its disastrous environmental impact. In this regard, the non-food terrestrial lignocellulosic biomass has emerged as the source of biogenic carbon since they are geographically diverse, available in plenty, inexpensive, and a component in many waste streams. Catalytic synthesis of organic chemicals from the carbohydrate fraction of biomass (e.g., cellulose, hemicellulose) through the furanic platforms has received particular attention. Acid-catalyzed dehydration of hexose sugars (e.g., glucose) and pentose sugars (e.g., xylose) derived from the cellulose and hemicellulose fractions lead to 5-(hydroxymethyl)furfural (HMF) and furfural (FUR), respectively. HMF and FUR have been established as commercially viable renewable chemical intermediates for synthesizing transportation fuels, organic chemicals, and synthetic polymers of commercial significance. The commercial production of HMF remains a challenge due to its inherent hydrophilicity and poor thermal and hydrolytic stability. In this regard, the hydrophobic congeners of HMF, such as 5- (acetoxymethyl)furfural (AcMF), have received much interest in recent years. The current focus is on the efficient production of AcMF and expanding its derivative chemistry. Several classes of products of commercial significance have been produced from FUR, HMF, and even AcMF. However, synthesizing denselyfunctionalized heterocycles from biorenewable furfurals is underexplored. The synthesis of heterocycles is a crucial area of synthetic organic chemistry since they are known for their biological activities and are found in many pharmaceuticals. Morita-Baylis-Hillman reaction, Biginelli reaction, and Hantzsch reaction can create remarkable structural complexities in a single step using structurally simple and easily available starting materials under catalytic conditions. Moreover, they are atomeconomical, high-yielding, scalable, and lead to important structural motifs for highvalue applications (e.g., pharmaceuticals). The substrate scope of these green transformations is typically limited to FUR. Therefore, a systematic study of these transformations using the 5-substituted-2-furaldehydes will not only improve the substrate scope of these reactions but also lead to novel products with interesting properties and expand the derivative chemistry of these biorenewable chemicals. In addition to the production of chemicals, the biogenic carbon in terrestrial cellulosic biomass can be transformed into renewable materials. For example, activated carbon (AC) can be produced by carbonizing biomass followed by activation. AC has a variety of conventional and emerging applications ranging from energy storage to catalyst support to water purification. Renewable synthesis of AC helps to mitigate the issue of managing waste biomass while generating value-added commodities. Therefore, producing valuable chemicals and materials from biomass is of interest from both academic and industrial perspectives.
Synthesis of highly-branched alkanes for renewable gasoline
(2020) Mascal M.; Dutta, Saikat
The gasoline market in the US is nearly twice that of diesel and jet fuel combined, and yet, nearly all research efforts to produce synthetic, biobased fuels center around these latter products. The reason for this is that a major component of gasoline is highly branched alkanes which, unlike straight chained products, are not readily derived from either fatty acid- or carbohydrate-based feedstocks. This review unpacks the motivations behind renewable gasoline synthesis and examines representative approaches to the targeted, de novo synthesis of densely-branched, high-octane isoalkanes and cycloalkanes employing chemocatalytic methods, as contrasted with the catalytic refining of biomass-derived feeds using petrochemical technologies. © 2019 Elsevier B.V.
Thermal Depolymerization of Scrap Tires Into Liquid Fuels: Upgradation and Utilization In Diesel Engine
(National Institute of Technology Karnataka, Surathkal, 2022) Mohan, Akhil; Madav, Vasudeva; Dutta, Saikat
Conversion of scrap tire into fuel oils has attracted commercial attention since revenue can be generated from inexpensive and abundant feedstock while easing waste management issues. Globally, 1.5 billion scrap tires are generated every year. Environmental accumulation of tire waste is a global problem, and one way to control the problem is to convert them into fuels and specialty chemicals. There are various approaches for recycling scrap tires, such as re-treading, reclaiming useful products for playgrounds, open incineration, pyrolysis, gasification, and illegal dumping. Illegal dumping often provides a site for breeding mosquitoes, rodents, and larvae formation. Open burning releases a thick black plume of smoke with 1,3-butadiene, nitrogen, carbon, and sulfur oxides with the release of hazardous polyaromatic hydrocarbons. Out of the approaches mentioned above to recycle tires, pyrolysis is an interesting energy recovery process due to the formation of solid (carbon black) and steel wires (in the case of the tire), pyro-gas, along oil products. Production of crude tire pyrolysis oil from scrap tires is a promising approach by thermal depolymerization at an oxygen starved atmosphere and a temperature of 400-600 oC. The primary objective of present study is to refine CTPO by the principle of selective adsorption and preferential solubility using cost-effective adsorbent and solvent and utilization as a fuel in a single-cylinder diesel engine. A field study was conducted in a 10-ton rotating autoclave reactor to optimize scrap tire pyrolysis parameters (400 oC, 10 oC/min, 0.2 bar, 4 rpm), and investigate the existing problems in the industry with a special focus on applying CTPO in diesel engines. Crude tire pyrolysis oil (CTPO) is a dark brown to black colored syrupy liquid with C6-C24 organic compounds with various classes such as paraffin, olefins, terpenes, aromatics, nitrogen, and sulfur-containing compounds, oxygen-containing compounds. The major challenge for utilizing CTPO in engine or furnace is the inferior fuel properties such as low heat content, low flash point, high acidity, low cetane index, creaming or phase separation in storage tanks, pungent smell due to the presence of dibenzothiophenes and mercaptans. However, thermal distillation is widely used as an upgradation technology implemented in most of the small scale tire pyrolysis units. Distillation needs huge capital investment and energy, making the process less attractive and unsuitable for the long-term run. In the present study, a straightforward, robust, inexpensive, and scalable up-gradation strategy for refining CTPO by preferential solubility and selective adsorption to utilize single-cylinder direct-injected stationary engines is formulated. A limited study has been attempted for the up- gradation of CTPO using adsorbents and solvents. The present study also envisages extensive characterization of CTPO, StTPO and diesel to comprehend the fuel chemistry in terms of physical, thermal, and chemical analysis through various analytical techniques. GC×GC TOF- MS analysis showed that sulfur, benzene derivatives, naphthalene’s and polyaromatic hydrocarbons were lowered by 48.86%, 25.68%, 43.69%, and 27.79%, respectively. The batch scale process's oil yield is improved by 95% compared to the laboratory scale upgradation strategy. Experimental results found that StTPO40 is a binary optimal blend in terms of performance, combustion, and emissions. The emissions from StTPOxx were significantly improved after upgradation by silica gel as adsorbent and petroleum ether as a diluent. Furthermore, ethyl levulinate, a potential bio-diluent with high oxygenate, was also utilized as an additive to StTPOxx blends to scrutinize performance, combustion, and emissions of single- cylinder, direct-injected stationary diesel engine, which is another novelty of the present study. The emission components are significantly dropped down after the upgradation of CTPO, but the performance was slightly lowered after the refining process. The nitrous oxide emission from StTPO40 and StTPO40EL10 was significantly reduced by 43.09% and 44.54%, respectively. Heat release from StTPOxx and StTPOxxEL10 were higher than diesel due to the high amount of polyaromatics hydrocarbons, naphthalenes, and benzene derivatives. StTPO40EL10 is a ternary optimal blend in terms of performance, combustion, and emission, with EL as a potential diesel additive. It can be concluded that the StTPOxx and StTPOxxEL10 can be fully utilized in a diesel engine without any modifications and operational failures. In short, the lower blend percentage of StTPO40EL10 and StTPO40 can be used as an alternative fuel for a single-cylinder direct- injected diesel engine. In contrast, the higher blend percentage (StTPO60EL10, StTPO80EL10, StTPO90EL10, StTPO60, StTPO80, and StTPO100) can be utilized in boilers, furnaces, burners and marine engines.