@article { ISI:000242960400016, title = {Rate enhancement in palladium catalyzed Heck reactions by Lewis acid promoters}, journal = {Catalysis Communications}, volume = {8}, number = {2}, year = {2007}, month = {FEB}, pages = {183-186}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Significant enhancement in the rate of Heck reactions has been achieved when catalytic amounts of Lewis acid (like FeCl(3)) promoters in the presence of trace amounts of water (\> 2000 ppm) are used along with Pd complex catalysts. Experiments with different aryl halides, bases as well as olefins have been carried out to demonstrate the role of Lewis acid promoters. The increase in the reaction rates is due to the weakening of Ar-X bond by the Lewis acid in the manner similar to Friedel-Crafts reaction. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Heck reaction, Lewis acid, Palladium, Promoters}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.05.043}, author = {Sud, Abhishek and Deshpande, Raj Madhukar and Chaudhari, Raghunath V.} } @article { ISI:000267625000020, title = {Hydroesterification of 2-vinyl-6-methoxynaphthalene using palladium complexes containing chelating nitrogen ligands}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {307}, number = {1-2}, year = {2009}, month = {JUL}, pages = {134-141}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Hydroesterification of 2-vinyl-6-methoxynaphthalene (VMN) to methyl ester of 6-methoxy naphthyl propionic acid (ester of naproxen) has been investigated using palladium complexes containing the chelating N(boolean AND)O and N(boolean AND)N ligands (pyridine-2-carboxylate, 2-acetylpyridine, 2-pyridine-carboxaldehyde, and bipyridine) as catalysts. Palladium complex containing 2-acetylpyridine as the ligand was found to be superior to other Pd-complexes. Both acid and halide promoters were necessary for high activity and selectivity. As an acid promoter, benzenesulfonic acid was found to be more effective compared to p-toluenesulfonic acid. Formation of ether 2-methoxy-6-(1-methoxyethyl)naphthalene and a polymer of VMN was observed in all the reactions. It was observed that active catalytic species generated during carbonylation reaction was responsible for the polymer formation. The effect of various parameters such as solvents, CO pressure, and alcohols on the catalytic activity as well as the selectivity was investigated. The turnover frequency using the complex Pd(acpy)(PPh(3))(OTs)(2) (acpy = 2-acetylpyridine) catalyst was found to be 42 h(-1), which is the highest for the hydroesterification of VMN. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {Carbonylation, Hydroesterification, Naproxen, Palladium complex, Polymer of VMN, Promoters}, issn = {1381-1169}, doi = {10.1016/j.molcata.2009.03.021}, author = {Atla, Shashi B. and Kelkar, Ashutosh A. and Chaudhari, Raghunath V.} } @article { ISI:000338806600067, title = {Enhanced kinetics for the clathrate process in a fixed bed reactor in the presence of liquid promoters for pre-combustion carbon dioxide capture}, journal = {Energy}, volume = {70}, year = {2014}, month = {JUN}, pages = {664-673}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

In this work, we present enhanced kinetics of hydrate formation for the clathrate process in the presence of two liquid promoters namely THF (tetrahydrofuran) and TBAB (tetra-n-butyl ammonium bromide) in a FBR (fixed bed reactor) for pre-combustion capture of CO2. Silica sand was used as a medium to capture CO2 from CO2/H-2 gas mixture by hydrate crystallisation. Experiments were performed at different temperatures (274.2 K and 279.2 K) and 6.0 MPa to determine the total gas uptake, induction time and rate of hydrate formation. The observed trends indicated that higher driving force resulted in higher gas consumption and significantly reduced induction time. For the same driving force, higher gas consumption and shorter induction time was achieved by THF as compared to TBAB. 5.53 mol\% THF attained higher gas consumption than 1.0 mol\% THF whereas 3.0 mol\% TBAB attained lower gas consumption than 0.3 mol\% TBAB. A highest gas uptake of 51.95 (+/- 5.183) mmol of gas/mol of water and a highest rate of 51.21(+/- 8.91) mol.min(-1).m(-3) were obtained for 5.53 mol\% THF at 6.0 MPa and 279.2 K. Overall, this study indicated better hydrate formation kinetics with the use of THF in an FBR configuration for CO2 capture from a fuel gas mixture. (C) 2014 Elsevier Ltd. All rights reserved.

}, keywords = {Carbon dioxide capture, Clathrate process, Fixed bed reactor, Gas hydrates, Pre-combustion capture, Promoters}, issn = {0360-5442}, doi = {10.1016/j.energy.2014.04.053}, author = {Babu, Ponnivalavan and Ho, Chie Yin and Kumar, Rajnish and Linga, Praveen} } @article { ISI:000335273100012, title = {Hydrogen storage in clathrate hydrates: Current state of the art and future directions}, journal = {Applied Energy}, volume = {122}, year = {2014}, month = {JUN}, pages = {112-132}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Hydrogen is looked upon as the next generation clean energy carrier, search for an efficient material and method for storing hydrogen has been pursued relentlessly. Improving hydrogen storage capacity to meet DOE targets has been challenging and research efforts are continuously put forth to achieve the set targets and to make hydrogen storage a commercially realizable process. This review comprehensively summarizes the state of the art experimental work conducted on the storage of hydrogen as hydrogen clathrates both at the molecular level and macroscopic level. It identifies future directions and challenges for this exciting area of research. Hydrogen storage capacities of different clathrate structures - sI, sII, sH, sVI and semi clathrates have been compiled and presented. In addition, promising new approaches for increasing hydrogen storage capacity have been described. Future directions for achieving increased hydrogen storage and process scale up have been outlined. Despite few limitations in storing hydrogen in the form of clathrates, this domain receives prominent attention due to more environmental-friendly method of synthesis, easy recovery of molecular hydrogen with minimum energy requirement, and improved safety of the process. (C) 2014 Elsevier Ltd. All rights reserved.

}, keywords = {Clathrates, Gas hydrates, Hydrogen hydrates, Hydrogen storage, Promoters, Storage capacity}, issn = {0306-2619}, doi = {10.1016/j.apenergy.2014.01.063}, author = {Veluswamy, Hari Prakash and Kumar, Rajnish and Linga, Praveen} } @conference { ISI:000375936100396, title = {Impact of pressure and temperature on tetra-n-butyl ammonium bromide semi-clathrate process for carbon dioxide capture}, booktitle = {International Conference on Applied Energy, ICAE2014}, series = {Energy Procedia}, volume = {61}, year = {2014}, note = {6th International Conference on Applied Energy (ICAE), Taipei, TAIWAN, MAY 30-JUN 02, 2014}, month = {MAY}, pages = {1780-1783}, publisher = {Elsevier Science BV}, organization = {Elsevier Science BV}, address = {Sara Burgerhartstraat 25, Po Box 211, 1000 AE Amsterdam, Netherlands}, abstract = {

The pre-combustion capture of CO2 in an IGCC power plant employing the hydrate based gas separation (HBGS) process is a novel method currently receiving attention around the world. Tetra-n-butyl ammonium bromide (TBAB) is a promoter that has been shown to improve the efficiency of hydrate formation. In this study, the effect of temperature and pressure on 0.3 mol\% TBAB solution is investigated. The induction time for the experiments conducted at 6.0 MPa and 274.8 K was found to be lower, while nucleation became increasingly random as temperature is increased and pressure is reduced. Total gas uptake and normalized rate of hydrate formation (NR5) is also the highest for the experiments conducted at 6.0 MPa and 274.8 K. However, it was found that the hydrate phase CO2 composition remains relatively constant at both reduced temperatures and pressures. (C) 2014 The Authors. Published by Elsevier Ltd.

}, keywords = {Carbon dioxide capture, Clathrate process, Gas hydrates, Gas separation, Promoters, tetra-n-butyl ammonium bromide}, issn = {1876-6102}, doi = {10.1016/j.egypro.2014.12.211}, author = {Babu, Ponnivalavan and Chin, Weng Inn and Kumar, Rajnish and Linga, Praveen}, editor = {Yan, J. and Lee, D. J. and Chou, S. K. and Desideri, U. and Li, H.} }