Papers by Professor G. Yadav
Organic Process Research & Development, 2002
ABSTRACT
Green Chem., 2002
ABSTRACT
Catalysis in green chemistry and engineering, 2018
We are launching a new journal for the benefit of those involved in research, education, practice... more We are launching a new journal for the benefit of those involved in research, education, practice and administration in the production of chemicals, materials and energy by using processes and practices that cover all those principles envisaged in Green Chemistry as well as Green Engineering which will also include all waste management and process intensification efforts from gram to kilogram to ton depending on the type of industry and need. We are most delighted to present to our readers with the first issue of "Catalysis in Green Chemistry and Engineering" (CGCE), the Avatar of erstwhile Bulletin of the Catalysis Society of India. Catalysis Society of India (CSI) represents more than 1000 members from academia, industry, and government organizations. CSI was formally founded in March 1973 at Banaras with Prof. S.K. Bhattacharyya as the President and Prof. J.C. Kuriacose as the Secretary. The main mandates of CSI are to encourage catalysis research in India, to organize professional meetings between researchers, to enhance mutual interactions, and to encourage cooperation between industry and academia. During the last three decades, the catalysis community in India has made significant strides both in applied and fundamental research. Several issues of the first volume will include the selected papers that were presented at the "7th Asia Pacific Congress on Catalysis (APCAT7)". APCAT is an International Conference which gathers fellow scientists, academicians, students, and delegates from industries all over the world with the aim to provide a high-profile and internationally renowned forum for researchers in catalysis science and technology. This event is organized every three years and for the first time, it was organized in India under Chairmanship of Professor G.D. Yadav, Vice Chancellor, Institute of Chemical Technology (ICT), Mumbai (also President of Catalysis Society of India) and Supported by Catalysis Society of India (CSI). The event was held from January 17 to January 21, 2017, at The Lalit, Mumbai, India. The theme of the event was "Catalysis for Sustainable Development, Peace and Prosperity". More than 500 delegates from 30 countries participated in this event. At this conference, 175 oral and 115 posters were presented along with 30 invited lectures that included plenary, keynote, and invited talks. We have invited 45 selected papers presented in the conference and after a rigorous peer review 18 papers were accepted for publication. Most of these papers covered the work on catalysts synthesis and its characterization and their applications for various reactions. We would like take this opportunity to thank all who kindly contributed their papers for these special issue of "Catalysis in Green Chemistry and Engineering" and reviewers for their kind help and co-operation. We are also obligated to Begell House Publishers, particularly, Dr. Yelena Shafeyeva, President, Begell House Inc. and the publishing and production teams for their assistance in preparation and publication of the journal.
Catalysis in Green Chemistry and Engineering
International Journal of Chemical Reactor Engineering, 2018
Enzymatic synthesis of molecules such as flavors, perfumes and fragrances has a great commercial ... more Enzymatic synthesis of molecules such as flavors, perfumes and fragrances has a great commercial advantage of being marketed as “natural” and also it offers exquisite selectivity of enzymes that can be superior over chemical catalysis. The current work focuses on the enzymatic synthesis of geranyl acetate as model compound, including optimization of reaction conditions such as nature of catalyst, reaction media, speed of agitation, mole ratio and temperature. A variety of esters were also synthesized. Geraniol was esterified with various acids, aromatic esters and vinyl esters in 1:4 molar ratio. Among all vinyl ester was the best giving in good yield (77–100 %) as compared to aromatic esters (5–82 %) and acids (7–31 %). Novozym 435 was found to be most active catalyst with ~96 % conversion and 100 % selectivity in 60 min at 55 °C in n-heptane as solvent for geranyl acetate. The maximum reaction rate was estimated (Vmax = 0.2712 mol L−1 min-1) by using the double reciprocal plot. It...
ChemistrySelect, 2018
In situ immobilization of laccase into metal‐organic framework (laccase‐MOF) was performed by ass... more In situ immobilization of laccase into metal‐organic framework (laccase‐MOF) was performed by assisting one‐pot synthesis strategy. A novel method to synthesize octahedral laccase‐MOF composite with enhanced thermostability is reported. The present work deals with entrapment of laccase into zeolitic imidazolate framework (ZIF‐8) by simply mixing solution of zinc acetate, 2‐methylimidazole, and laccase at room temperature (28 ± 2 °C). Fourier transform‐infrared spectroscopy (FT‐IR), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), and Confocal scanning microscopy were employed to characterize laccase‐MOF composite. The thermostability of prepared composite was assessed concerning half‐life at varying temperatures which conferred 3.6‐fold enhancement over free enzyme. Also, kinetic studies of immobilized laccase showed a slightly higher Km and lower Vmax values along with the enhancement of thermodynamic parameters after non‐covalent interaction. Moreover, the imm...
Flavour and Fragrance Journal, 2019
Increasing environmental awareness has forced researchers to minimize the use of organic solvents... more Increasing environmental awareness has forced researchers to minimize the use of organic solvents in chemical synthesis. Modern biocatalysis is a way to develop clean catalytic technologies. A process operating in solvent‐free condition using reusable biocatalyst, will be useful for the fragrance and flavour industry, which requires stringent specifications on impurities. A direct transesterification reaction of geraniol with ethyl acetate was carried out to produce geranyl acetate in a batch reactor using different immobilized enzymes. Among these, Novozyme 435 was the best catalyst for the synthesis of geranyl acetate in a solvent‐free medium. Parametric studies were conducted to optimize the conversion and yield. Overall, 83% conversion of geraniol with 100% selectivity to geranyl acetate was obtained at a mole ratio of 1:7 of geraniol to ethyl acetate, using 12.7 g L−1 Novozyme 435 at 60 °C for 2 h. At higher concentrations of acyl donor, it was noticed that the conversion of g...
Clean Technologies and Environmental Policy, 2019
Currently, production of high-purity hydrogen (H 2) in a viable and sustainable manner is highly ... more Currently, production of high-purity hydrogen (H 2) in a viable and sustainable manner is highly sought. H 2 generation is possible by water splitting or biomass conversion as renewable resources. Bio-based n-butanol is a potential candidate for H 2 production via catalytic steam reforming (SR) which is both of industrial and scientific significance. In the current work, a new catalyst is developed using La-Mg-based mixed metal oxide as support loaded with Ni-Cu as metals promoted by a suitable noble metal from Pt, Ru and Pd for steam reforming of n-butanol (SRB) in a fixed bed reactor. The effects of temperature, steam to carbon (S/C) ratio and gas hourly space velocity on hydrogen production from n-butanol were studied systematically. High n-butanol conversion (> 75%) and H 2 yield (> 70%) were obtained. Particularly, the promotion with Pt resulted in the highest H 2 concentration (> 90 mol%) with long-term stability of 25 h. The process optimization studies revealed that at T = 773 K, steam/carbon ratio (S/C) = 6 mol/mol and GHSV = 3120 h −1 , maximum H 2 concentration was obtained. The promotion with noble metals was further justified by the absence of coke formation and minimal metal sintering because noble metals help avert oxidation of Ni and Cu maintaining their active form. It was further bolstered through the cyclic stability studies which demonstrated that all catalysts remained stable for longer periods. A possible reaction mechanism on the synthesized catalysts is proposed in consonance with experimental data.
ChemistrySelect, 2019
Raspberry ketone, also called as rheosmin, is an important flavor compound used in perfumery and ... more Raspberry ketone, also called as rheosmin, is an important flavor compound used in perfumery and food industry. In the current work, it was synthesized from p‐hydroxybenzaldehyde (PHB) and acetone in one pot system. Crossed aldol condensation of p‐hydroxybenzaldehyde gave α,β‐unsaturated ketone, i. e. p‐hydroxybenzalacetone (PHBA) which was further reduced to obtain raspberry ketone. Mixed oxide catalysts of different combinations of Mg, La and Zn were prepared by three different methods such as hydrothermal, combustion and co‐precipitation. Among all Zn−La with mole ratio 3:1, synthesized by combustion method and glycine as fuel, gave the best results for selective synthesis of PHBA. For hydrogenation of PHBA, Ni, Cu and Pd metals were screened to find that 2% Ni/Zn3:La1 was the best catalyst for one‐pot synthesis of raspberry ketone. It showed excellent textural properties like high surface area (680 m2/g), activity and selectivity. The virgin and spent catalyst samples were fully...
Clean Technologies and Environmental Policy, 2018
Cost-effective valorization of carbon dioxide into bulk and specialty chemicals using catalysis w... more Cost-effective valorization of carbon dioxide into bulk and specialty chemicals using catalysis will be attractive in the foreseeable future. 1,3-Oxazolidin-2-one derivatives are one of the important classes of heterocyclic compounds which have wide applications in pharmaceutical industries due to their biological activities such as antibacterial, antimicrobial, antiseptic. Various synthetic routes are employed to prepare these compounds which include phosgenation, oxidative carbonylation, etc., which make use of polluting chemicals and homogeneous catalysts. The heterogeneous catalytic processes to synthesize these derivatives are quite limited. Thus, developing a green route which is environmental friendly is highly desirable. The current work deals with development of a heterogeneous reusable catalyst and its application to synthesize 1,3-oxazolidin-2-one derivatives using carbon dioxide as a C1 source. The fact that no use of promoter or organic co-catalyst is made in the current process makes the synthesis route more favorable. Pure La-MgO and K-La-MgO with different K loading (1, 3, 5, and 7 wt%) synthesized by combustion route were screened for carbonylation of diethanol amine. 5% K-La-MgO was found to be the best catalyst. The catalyst was well characterized in virgin form and after use by various analytical techniques like TEM, SEM, XRD, CO 2 and NH 3-TPD, BET surface area analysis. With 5% K-La/MgO, 72% conversion of diethanol amine was achieved with 100% selectivity of the desired product at optimum conditions, i.e., 150 °C, 5 wt% K-La/MgO catalyst loading of 0.02 g/cm 3 and 2.0 MPa CO 2 pressure. Reaction mechanism was proposed and kinetic model developed. The apparent activation energy was calculated as 18.76 kcal/mol. The catalyst was robust and recyclable. The process is clean and green. Keywords Diethanol amine • Carbon dioxide • Carbonylation • 1,3-Oxazolidin-2-one derivatives • Solid base catalyst • K-La-MgO mixed oxide List of symbols La-MgO Lanthanum-magnesium mixed oxide K-La-MgO Potassium incorporated lanthanum-magnesium mixed oxide D Reactant species, diethanol amine E Reactant species, CO 2 A i Acidic site B i Basic sites DA 1 Chemisorbed D on acidic site A EB 2 Chemisorbed E on basic site B FA 1 Chemisorbed 3-(2-hydroxyethyl)-1,3-oxazolidin-2-one GB 2 Chemisorbed water C D Concentration of D (mol/cm 3) C E Concentration of E (mol/cm 3) C F Concentration of F (mol/cm 3) C G Concentration of G (mol/cm 3) C DA1 Concentration of D at solid (catalyst) surface (mol/g-cat) C EB2 Concentration of Eat solid (catalyst) surface (mol/g-cat) C FA1 Concentration of F at solid (catalyst) surface (mol/g-cat) Electronic supplementary material The online version of this article (
Clean Technologies and Environmental Policy, 2018
Kraft lignin (KL) released from pulp and paper industries could cause severe environmental contam... more Kraft lignin (KL) released from pulp and paper industries could cause severe environmental contamination. Appropriate effluent treatment is needed to mitigate the pollution. A novel strategy for biodegradation of KL by integrating photolysis with microbial oxidation process is reported. Results unveiled degradability of solar-treated KL (SKL) using a potential microbial strain: Trametes hirsuta MTCC-1171. Initially, KL was photodegraded by solar treatment. To analyze the chemical and physical changes in KL after solar treatment, scanning electron microscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography were employed. Photolytic pretreatment induced depolymerization of chains in KL along with the cleavage of aromatic rings which made it amiable to further microbial degradation. SKL was used as a substrate to produce laccase during microbial degradation. The maximum activity of laccase of 7.1 ± 0.02 U/mL was observed on the 4th day of incubation. Microbial degradation products of photo-treated and untreated KL were identified using GC-MS. Intensification in KL degradation has been noticed along with the conversion of value-added products such as vanillin, valeric acid, and various higher alcohols. The results contribute an evidence of notable modifications of KL into value-added products using an innovative approach, which is eco-friendly and energy-efficient as well.
Clean Technologies and Environmental Policy, 2018
Esters of salicylic acid are in demand for the synthesis of drugs, food preservatives, pharmaceut... more Esters of salicylic acid are in demand for the synthesis of drugs, food preservatives, pharmaceuticals, perfumes and solvents. A novel sulfated Fe 2 O 3-ZrO 2 catalyst with different iron loadings was prepared by the combustion technique and used in the preparation of methyl salicylate from salicylic acid and dimethyl carbonate. This process is a viable and safe substitute to other esterification processes, involving harmful alkylating agents and chemicals. The activity of sulfated Fe 2 O 3-ZrO 2 was evaluated for the esterification of salicylic acid with dimethyl carbonate. No solvent was used and hence the quality of the product was excellent. The product methyl salicylate is extensively used in the food and pharma industries. Catalysts with different loadings of iron on zirconia (5, 10, 15, 20 wt.%) were synthesized, and their activities evaluated vis-à-vis ZrO 2 and sulfated zirconia. The catalysts were characterized using SEM, XRD, FTIR, TGA, NH 3-TPD and BET surface area analysis. The activity of the catalysts increases after the loading of iron on zirconia and 10 wt.% sulfated Fe 2 O 3-ZrO 2 gave the highest acidity and activity for the synthesis of methyl salicylate. The effect of various kinetic parameters on the rate of esterification of salicylic acid was studied. The optimum conditions for 99% conversion of salicylic acid with 100% selectivity was 120 °C after 150 min at a 1:10 molar ratio of salicylic acid to dimethyl carbonate and catalyst loading of 0.03 g/cm 3. The reaction mechanism and kinetics were studied. The activation energy for this reaction was found to be 13.82 kcal/mol.
ChemistrySelect, 2018
Ionic liquids have been established as solvents and catalysts in a number of reactions due to the... more Ionic liquids have been established as solvents and catalysts in a number of reactions due to their unique properties. In this study, we have synthesized sulfonic acid functionalized imidazolium based strongly acidic ionic liquid supported on graphene oxide (PTS−Im‐3@GO). PTS−Im‐3@GO was synthesized by grafting 1‐(4‐sulfobutyl)‐3‐(3‐propyltriethoxysilyl)imidazolium hydrogen sulfate onto graphene oxide (GO) by covalent bonds. The prepared PTS−Im‐3@GO was used for regio‐selective ring opening reaction of styrene oxide with isopropyl alcohol giving 95% conversion and 100% regio‐selectivity towards 2‐isopropoxy‐2‐phenylethan‐1‐ol at 50 °C. The activity of the said catalyst was compared with various heterogeneous catalysts such as GO, PTS−Im‐1@GO, PTS−Im‐2@GO, PTS−Im‐1, PTS−Im‐2, PTS−Im‐3, Hβ‐zeolite, and montmorillonite K‐10. Among all catalysts, PTS−Im‐3@GO showed good conversion towards the desired product. PTS−Im‐3@GO was characterized by FTIR, SEM, EDS, TGA, XRD, 29Si NMR, XPS and C...
Topics in Catalysis, 2004
There is a need to develop green, clean and smart chemical technologies. Waste reduction through ... more There is a need to develop green, clean and smart chemical technologies. Waste reduction through clever strategies and catalysis are at the heart of green chemistry. In the case of over 600 industrial phase transfer catalyzed (PTC) processes in several industries, mostly practised as liquid-liquid PTC, the catalyst is not recovered and disposed as a waste. Liquid-liquid PTC can be replaced by solid-liquid (S-L), liquid-liquid-liquid (L-L-L), solid (catalyst)-liquid-liquid, solid-liquid-omega liquid, gas-liquid-solid (G-L-S) and capsule membrane PTC to recover and reuse the catalyst and also to enhance selectivity, thereby advocating the realm of green PTC. Use of microwaves and ultrasound will also help in increasing rates. MILL-PTC and MISL-PTC are attractive techniques to enhance rate and selectivities under mild input of microwave irradiation (MI). In cascade-engineered PTC, several steps are combined in a reactor using the same catalyst and solvent, if used at all, without separation, or with partial replenishment of the reactants for all the steps to get substantial waste minimization. This paper provides a new insight into PTC for some reactions of industrial importance.
Clean Technologies and Environmental Policy, 2017
The high consumption of mono-ethylene glycol phenyl ether in various sectors requires clean and g... more The high consumption of mono-ethylene glycol phenyl ether in various sectors requires clean and green synthesis. Herein, we report an efficient, selective and green route of hydroxylation using calcined hydrotalcite (CHT) for the preparation of mono-ethylene glycol phenyl ether. Various types of solid base catalysts were prepared and well characterized by TGA-DSC, FTIR, XRD, CO 2-TPD, NH 3-TPD, SEM and BET surface area. The catalyst CHT (3:1) possesses very high activity for hydroxyalkoxylation of phenol and ethylene glycol with 96% conversion at 180°C in 2 h with catalyst loading of 0.03 g cm-3. The insight of reaction reveals that it is kinetically controlled with second-order reaction and follows power law model. The apparent activation energy for the reaction is 21.3 kcal mol-1. The catalyst is highly reusable and shows green chemistry prospective and gives excellent results up to four runs.
Clean Technologies and Environmental Policy, 2016
Esters find several applications such as solvents, flavours and fragrants and intermediates in sy... more Esters find several applications such as solvents, flavours and fragrants and intermediates in synthesis of drugs. In the present work, 2-methoxy phenyl benzoate was efficiently synthesized from guaiacol and benzoic anhydride by acylation. A variety of catalysts such as hydrotalcite and alkali-promoted hydrotalcite was synthesized. Potassium-promoted hydrotalcite (K/HT) calcined at 500 °C for 6 h was active, selective and reusable. It was characterized by different techniques. A slurry batch reactor was used to study reaction mechanism and kinetics. 2-Methoxy phenyl benzoate was efficiently obtained with 100% selectivity at guaiacol conversion of 98% over K/HT at 100 °C after 6 h. A power law model with second-order kinetics was fitted to obtain an apparent activation energy of reaction of 21.1 kcal mol -1 . The process is clean and green.
The Journal of Physical Chemistry A, 2005
The alkylation of m-cresol with isopropyl alcohol in the presence of novel superacidic catalysts ... more The alkylation of m-cresol with isopropyl alcohol in the presence of novel superacidic catalysts named as UDCaT-4, UDCaT-5, and UDCaT-6 was investigated. The catalysts are modified versions of zirconia showing high catalytic activity, stability, and reusability in the presence of water as compared to conventional sulfated zirconia. The objective of the present investigation was to explore the potential of these catalysts in this alkylation of m-cresol with isopropyl alcohol to thymol, which has widescale applications. The reactions were conducted in liquid phase in the temperature range of 433-473 K. Both, O-and C-alkylated products were obtained at lower temperatures, while at higher temperatures, thymol was the main product of the reaction. The catalytic activity increases in the order UDCaT-5 > UDCaT-6 >UDCaT-4 > sulfated zirconia. Thymol could be efficiently obtained with selectivity reaching up to 79% at an isopropyl alcohol conversion of 92% with UDCaT-5. This process can be a replacement for the existing process based on zeolites where high temperature and pressure are required. Synergistic effects of very high sulfur content present (9% S) and preservation of the tetragonal phase in UDCaT-5, in comparison with sulfated zirconia (4% S), were responsible for higher catalytic activity. A systematic investigation of the effects of various operating parameters was accomplished, and a mathematical model is developed to describe the reaction pathway and validated with experimental results. The reaction was carried out without using solvent, and the process subscribes to the principles of green chemistry.
Process Biochemistry, 2000
A chemo-enzymic route was devised for the synthesis of glyoxalic acid from glyoxal. Glyoxal was c... more A chemo-enzymic route was devised for the synthesis of glyoxalic acid from glyoxal. Glyoxal was converted chemically to glycolic acid, which was oxidised to glyoxalic acid with a glycolate oxidase from spinach. The two steps were studied independently as well as singly. The conversion of glyoxal to glycolic acid was 95% at a mol ratio of 1:1.5, giving 98% selectivity
Microporous and Mesoporous Materials, 1999
Zirconium oxide, or zirconia, when modified with anions such as sulfate ions forms a highly acidi... more Zirconium oxide, or zirconia, when modified with anions such as sulfate ions forms a highly acidic or superacidic catalyst depending on the treatment conditions. This catalyst is found to be well suited for catalyzing reactions of industrial importance, eg hydrocarbon isomerization, ...
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Papers by Professor G. Yadav