@article { ISI:000226532100006, title = {Factors affecting activation and utilization of carbon dioxide in cyclic carbonates synthesis over Cu and Mn peraza macrocyclic complexes}, journal = {Journal of Molecular Catalysis A - Chemical}, volume = {226}, number = {2}, year = {2005}, month = {FEB}, pages = {199-205}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The catalytic activities of several Cu and Mn aza complexes for cyclic carbonate synthesis from CO2 and epoxides are reported. The various factors affecting activation of CO2 by metal complexes and its utilization in cyclic carbonate synthesis have been investigated. Fr-IR, UV-vis and EPR spectroscopic investigations reveal that CO2 coordinates to Cu in eta(1)-C mode of coordination. Nature of the ligand and substitution influence the lability of metal-CO2 bonding. The differences in the catalytic activities are correlated with the mode and strength of CO2 binding. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {benign synthesis, Carbon dioxide, catalysis by Cu and Mn complexes, CO2 activation, CO2 fixation, CO2 utilization, cyclic carbonates, polycarbonates, spectroscopy}, issn = {1381-1169}, doi = {10.1016/j.molcata.2004.10.034}, author = {Srivastava, R. and Bennur, T. H. and Srinivas, D.} } @article { ISI:000250399300023, title = {Spectroscopic and catalytic properties of SBA-15 molecular sieves functionalized with acidic and basic moieties}, journal = {Microporous and Mesoporous Materials}, volume = {105}, number = {1-2}, year = {2007}, month = {SEP}, pages = {170-180}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

SBA-15, grafted with Lewis acidic Ti4+ ions and basic amines (imidazole, guanine or adenine) exhibited high catalytic activity in the cycloaddition of CO2 to epoxides yielding selectively cyclic carbonate precursors of polycarbonates. In the second class of materials, the surface of SBA-15 was grafted with thiol or sulfonic acid functionalities. Mn(Salen)Cl was, then, covalently bound to these acidic groups. The resulting catalysts show enhanced chemo-, regio- and stereo-selective catalytic activity in the epoxidation of terpenes such as R-(+)limonene, alpha-pinene and Delta-carene with molecular oxygen. The acid-base properties of these modified SBA- 15 materials were investigated by temperature-programmed desorption and diffuse-reflectance infrared Fourier transform spectroscopy. Ammonia and pyridine were used as probe molecules for acidic sites and CO2 for basic sites. Acidic Ti sites activated epoxides and the grafted basic amines activated CO2. The simultaneous presence of both acidic and basic sites on amine/adenine-functionalized Ti-SBA-15 enabled synergistic enhancement in catalytic activity in the cycloaddition reaction of CO2 to epoxides. When Mn(Salen)Cl was immobilized on thiol or sulfonic acid-functionalized SBA-15, the oxidation state of Mn decreased from +3 to +2. The organo-acidic functional groups (thiol or sulfonic acid) axialk, coordinated to Mn ions modified the electronic structure of Mn ions enhancing the activity and selectivity of Mn(Salen) complexes in aerial oxidation reactions. (C) 2007 Elsevier Inc. All rights reserved.

}, keywords = {aerial oxidation of terpenes, CO2 utilization, cyclic carbonates synthesis, epoxidation, functionalization with acidic and basic moieties, immobilization of Mn complexes, organo-functionalization of SBA-15, solid acid-base catalysts}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2007.05.024}, author = {Srinivas, D. and Ratnasamy, P.} } @article { ISI:000285819500015, title = {Thermoneutral point analysis of ethanol dry autothermal reforming}, journal = {Chemical Engineering Journal}, volume = {165}, number = {3}, year = {2010}, month = {DEC}, pages = {864-873}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

{Dry autothermal reforming of ethanol can be used to produce a variety of value added products like hydrogen, syngas and also carbon (possible CNF). A thermodynamic analysis of dry autothermal reforming of ethanol has been carried out to locate the thermoneutral temperatures and product composition at those points at 1, 3, 6 and 9 bar reaction pressures. The variations of thermoneutral temperatures and individual product yields at those temperatures have been discussed to find the optimum operating parameters for desired product output from the process. The process operated at thermoneutral conditions can give useful products like hydrogen, syngas (of low ratio) and carbon (possibly CNFs) and also provide a way for CO2 sequestration using renewable ethanol fuel. A maximum of 2.58 moles of syngas of ratio 2.01 obtained at 1 bar

}, keywords = {CO2 utilization, Dry autothermal reforming, Ethanol reforming, Thermoneutral}, issn = {1385-8947}, doi = {10.1016/j.cej.2010.10.033}, author = {Kale, Ganesh R. and Kulkarni, Bhaskar D.} } @article { ISI:000315616400005, title = {Hydrogen generation with CO2 utilization: a solvay cluster study}, journal = {International Journal of Hydrogen Energy}, volume = {38}, number = {6}, year = {2013}, month = {FEB}, pages = {2624-2633}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

The fuel cell economy is yet to start research programs in hydrogen generation with CO2 utilization for hydrocarbon reforming processes used in fuel processor applications. A simple thermodynamic study using solvay clusters was done to investigate the feasibility of using the carbon species produced in the steam methane reforming process to produce value added chemicals. The results of this study are highly encouraging to start process development of closed systems of hydrogen generation with CO2 conversion to acetic acid/acrylic acid making easier the commercialization of fuel cells and hydrogen energy. Such studies can be specifically carried out for different fuel processor systems. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {CO2 utilization, Fuel processing, Gibbs energy, Solvay clusters, Steam reforming}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2012.11.129}, author = {Kale, Ganesh R. and Kulkarni, Bhaskar D.} } @article { ISI:000333724000022, title = {Combined gasification of lignite coal: thermodynamic and application study}, journal = {Journal of the Taiwan Institute of Chemical Engineers}, volume = {45}, number = {1}, year = {2014}, month = {JAN}, pages = {163-173}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Combined gasification (a combination of steam gasification and CO2 gasification) without air is an important process for research in coal gasification to reduce the steam generation energy in the gasification system and also to enhance the slow CO2 gasification reaction. A thermodynamic study involving the effect of temperature, pressure and feed CO2 and steam ratios in gasification of lignite coal was studied in this paper. The product generation trends of syngas and methane with carbon (in coal) conversion were studied in detail. The carbon (in lignite coal) was converted completely at a lower temperature than pure carbon in the combined gasification. Some applications of the gasifier product gas were also studied. Combined gasification offers great advantages to produce syngas of exact ratio in one step for use in petrochemical manufacture and fuel cell systems. The complete carbon (in coal) conversion occurred beyond the thermoneutral gasification temperature in the study. The combined gasification process was a useful way for CO2 utilization reducing the net CO2 emission to the atmosphere. (C) 2013 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

}, keywords = {CO2 utilization, Coal gasification, Coal to syngas, Combined gasification, Thermodynamic study}, issn = {1876-1070}, doi = {10.1016/j.jtice.2013.04.015}, author = {Kale, Ganesh R. and Kulkarni, Bhaskar D. and Chavan, Rank N.} } @article { ISI:000340306500036, title = {Effects of method of preparation on catalytic activity of Co-Zn double-metal cyanide catalysts for copolymerization of CO2 and epoxide}, journal = {Applied Catalysis A-General}, volume = {482}, year = {2014}, month = {JUL}, pages = {300-308}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Co-Zn double-metal cyanide (DMC) complexes are well-known catalysts for ring-opening polymerization of epoxides and co-polymerization of CO2 and epoxides. This work provides an insight on structure-activity relationship of DMC for poly(cyclohexene carbonate) synthesis. Seven samples of DMC were prepared by different methods and mode of reagent addition. Highly active catalyst could be synthesized even without using a co-complexing agent. CO2 adsorption studies revealed that higher the guest-host interaction higher would be the catalytic activity. High density and strength of Lewis acid sites, moderate crystallinity, low crystal symmetry (rhombohedral/monoclinic), Cl- ions and coordinated tert.-butanol (complexing agent) control the catalytic activity for polycarbonates. Chloride in the structure avoided induction period by increasing acidity of the catalyst and thereby, improving the guest-host interactions. Polycarbonates with CO2 incorporation as high as 86 mol\%, average molecular weight of 20900 and polydispersity index of 1.8 were prepared at complete conversion of cyclohexene oxide. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Carbon dioxide, CO2 utilization, Copolymerization of CO2 and cyclohexene oxide, Double-metal cyanide, Polycarbonate, Structure-activity relationship}, issn = {0926-860X}, doi = {10.1016/j.apcata.2014.06.007}, author = {Sebastian, Joby and Srinivas, Darbha} } @article { ISI:000334895800021, title = {Solid, double-metal cyanide catalysts for synthesis of hyperbranched polyesters and aliphatic polycarbonates}, journal = {Journal of Chemical Sciences}, volume = {126}, number = {2, SI}, year = {2014}, note = {21st National Symposium on Catalysis (CATSYMP), CSIR Indian Inst Chem Technol, Hyderabad, INDIA, FEB 11-13, 2013}, month = {MAR}, pages = {499-509}, publisher = {Catalysis Soc India}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

Fe-Zn and Co-Zn double-metal cyanide (DMC) complexes exhibit highly efficient and selective catalytic activity for synthesis of hyperbranched polyesters (glycerol succinic acid (G-SA) and glycerol adipic acid (G-AA)) and aliphatic polycarbonates (via., alternative co-polymerization of cyclohexene oxide and CO2), respectively. The influence of method of preparation of DMC, in particular the mode of addition of reagents, on its physicochemical and catalytic properties was investigated. Co-Zn DMC was found highly selective for polycarbonate (than polyethers) formation. Catalysts prepared using tert-butanol and PEG-4000 as complexing and co-complexing agents, respectively, were found superior to those prepared without these agents. Apart from its role as a coordinating ligand, tert-butanol activated the Lewis acidic Zn2+ sites for reactions in polyester and polycarbonate formation. Hydrophobicity, micro-mesoporosity, acid strength and the amount of coordinated complexing agent are some of the crucial factors influenced the catalytic activity of DMC complexes.

}, keywords = {aliphatic polycarbonate, CO2 utilization, Double-metal cyanide complex, heterogeneous catalysis, hyperbranched polyester}, issn = {0974-3626}, author = {Sebastian, Joby and Darbha, Srinivas} } @article { ISI:000334306500004, title = {Thermoneutral conditions in dry reforming of ethanol}, journal = {Asia-Pacific Journal of Chemical Engineering}, volume = {9}, number = {2}, year = {2014}, month = {MAR}, pages = {196-204}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

The reaction enthalpy (Delta H) of reforming processes like steam and dry (CO2) reforming is of great importance for scale-up and process development. Generally, the reforming processes are considered endothermic in nature. However, a detailed study of the reaction enthalpy of reforming process, taking the example of dry reforming of ethanol considered in this study, reveals the existence of exothermic reaction enthalpy at low temperatures. A study of reaction enthalpy of ethanol dry reforming within pressure (1-10 bar), temperature range (300-900 degrees C), and CO2 to carbon in ethanol ratio (CCER 1-5) was initiated to determine the existence of thermoneutral temperatures for the overall reaction. The variation of thermoneutral conditions and product yields at the thermoneutral temperatures was studied. The utilization potential of the products generated at thermoneutral conditions was also evaluated. The low-pressure thermoneutral operation favored higher hydrogen production, lower methane and water formation, whereas the high-pressure thermoneutral operation favored product gas of lower syngas ratio with higher CO2 conversion (utilization) in the process. The study can be extended to steam and dry reforming of other fuels to generate valuable products at thermoneutral conditions avoiding use of air in the process and subsequent N-2 dilution of the product gas. (c) 2013 Curtin University of Technology and John Wiley \& Sons, Ltd.

}, keywords = {carbon nanofilaments, CO2 utilization, Dry reforming, ethanol to syngas, thermoneutral process}, issn = {1932-2135}, doi = {10.1002/apj.1759}, author = {Kale, Ganesh R. and Kulkarni, Bhaskar D.} } @article { ISI:000364886500019, title = {Factors influencing catalytic activity of Co-Zn double-metal cyanide complexes for alternating polymerization of epoxides and CO2}, journal = {Applied Catalysis A-General}, volume = {506}, year = {2015}, month = {OCT}, pages = {163-172}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Co-Zn double-metal cyanides (DMCs) show good catalytic activity towards copolymerization of epoxides and CO2. A deep insight into the structural aspects of the catalysts that control their catalytic performance is addressed in this work. Method of preparation of DMC catalysts was found to have influence on their structure, which in turn dictated their catalytic activity. Complexing agent (t-BuOH) and density of strong acid sites of DMC catalysts were found critical factors responsible for their activity. Selectivity of DMC towards polycarbonates depends on the amount of alkali ion content in their composition. Induction period of the catalysts was governed by the strength of acid sites and by the presence of dispersed ZnCl2 in the composition. This study provides an understanding of the prime features of DMC catalysts that can be tuned for high productivity of polycarbonates. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {CO2 utilization, Copolymerization of epoxides and CO2, Double-metal cyanide, Polycarbonate}, issn = {0926-860X}, doi = {10.1016/j.apcata.2015.09.010}, author = {Sebastian, Joby and Srinivas, Darbha} } @article {45886, title = {Supported imidazole as heterogeneous catalyst for the synthesis of cyclic carbonates from epoxides and CO2}, journal = {Catalysis Communications}, volume = {59}, year = {2015}, month = {JAN }, pages = {201-205}, type = {Article}, abstract = {

Imidazole anchored onto a silica matrix, by means of a propyl linkage, is found to be an effective heterogeneous catalyst for the synthesis of cyclic carbonates from epoxides and CO2 in near quantitative yield. The versatility of this catalyst is demonstrated by using different substrates (epichlorohydrin, propylene oxide, butylene oxide and styrene oxide) for this cycloaddition reaction. These CO2 insertion reactions were typically carried out in the temperature range of 343 to 403 K at 0.6 MPa CO2 pressure under solvent-free conditions. Several spectroscopic methods were used to characterize the catalyst and study the integrity of the fresh and spent catalysts. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Anchored imidazole, CO2 utilization, cyclic carbonates, epoxides}, issn = {1566-7367}, doi = {10.1016/j.catcom.2014.10.026}, author = {Sankar, Meenakshisundaram and Ajithkumar, Thalasseril G. and Sankar, Gopinathan and Manikandan, Palanichamy} } @article { ISI:000377891600014, title = {Direct synthesis of dimethyl carbonate from CO2 and methanol over CeO2 catalysts of different morphologies}, journal = {Journal of Chemical Sciences}, volume = {128}, number = {6}, year = {2016}, month = {JUN}, pages = {957-965}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

The direct synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO2) and methanol is an attractive approach towards conversion of the greenhouse gas - CO2 into value-added chemicals and fuels. Ceria (CeO2) catalyzes this reaction. But the conversion efficiency of CeO2 is enhanced when the byproduct water in the reaction medium is separated by employing trapping agents like 2-cyanopyridine (2-CP). In this work, the influence of morphology of CeO2 on the direct synthesis of DMC in presence of 2-CP is reported. CeO2 catalysts of cube, rod, spindle and irregular morphology (Ce - C, Ce - R, Ce - S and Ce - N, respectively) were prepared, characterized and studied as catalysts in the said reaction conducted in a batch mode. Among all, Ce - S shows superior catalytic performance with nearly 100 mol\% of DMC selectivity. Catalytic activity correlates with the concentration of acid and base sites of medium strength as well as defect sites. Ce - S has an optimum number of these active sites and thereby shows superior catalytic performance.

}, keywords = {acid-base catalysis, ceria, CO2 utilization, Dimethyl carbonate, influence of morphology}, issn = {0974-3626}, doi = {10.1007/s12039-016-1094-0}, author = {Unnikrishnan, P. and Darbha, Srinivas} } @article {48182, title = {Protophilic solvent-impelled quasi-catalytic CO2 valorization to formic acid and N-formamides}, journal = {Fuel}, volume = {326}, year = {2022}, month = {OCT}, pages = {125074}, type = {Article}, abstract = {

As a low-price and luxuriant C1 sustainable resource, CO2 has the privilege of synthesizing hydrogen carriers and valuable chemicals. However, expensive metallic and organic catalysts are often indispensable for going on wheels of the relevant reaction processes. In this work, a protophilic solvent-impelled quasi-catalytic system was developed for efficient synthesis of formic acid and various N-formamides with high yields of 76-94\% via reductive CO2 functionalization under mild reaction conditions (50 ?). Direct activation of the liquid hydrosilane toward the reduction of CO2 enabled by DMSO with optimum basicity/protophilicity is the predominant reaction route among the examined interaction models, while carbonic acid potentially derived from excessive CO2 and residual water inhibits the reaction, as explicitly disclosed by theoretical calculations and isotope labeling experiments. In addition, the in situ formed O-formyl species is conductive to the cascade CO2 reduction steps, which remarkably facilitated the overall quasi-catalytic upgrading process.

}, keywords = {CO2 utilization, Formic acid, Green energy, Nitrogenous chemicals, Quasi-catalysis}, issn = {0016-2361}, doi = {10.1016/j.fuel.2022.125074}, author = {Wu, Hongguo and Li, Hu and Zhao, Wenfeng and Sudarsanam, Putla and Yang, Song} }