@article { ISI:000242010600002, title = {Hydrophobic, solid acid catalysts for production of biofuels and lubricants}, journal = {Applied Catalysis A-General}, volume = {314}, number = {2}, year = {2006}, month = {NOV}, pages = {148-159}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A novel application of Fe-Zn double-metal cyanide (DMC) complexes as solid catalysts in the preparation of fatty acid alkyl esters (biodiesel/biolubricants) from vegetable oils is reported. The catalysts are hydrophobic (no H2O adsorption at reaction temperatures) and contain only Lewis acidic sites (NH3 and pyridine adsorption). Bronsted acid sites are absent (absence of 1546 and 1639 cm(-1) bands on adsorption of pyridine). Basic sites are also absent (no CO2 adsorption). Unlike the homogeneous or other solid catalysts (like ZnO-Al2O3, for example), the Fe-Zn, DMC catalysts are highly active even for the simultaneous transesterification of triglycerides and esterification of the free fatty acids (FFA) present in unrefined and waste cooking oils as well as non-edible oils. They are also tolerant of water, probably, due to their surface hydrophobicity. A relationship between the transesterification activity and the concentration of strong Lewis acid sites has been observed. Coordinatively unsaturated Zn2+ ions in the structure of the Fe-Zn complex are the probable active sites. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {alcoholysis of vegetable oils, Biodiesel, Biolubricants, double-metal cyanides (DMC), esterification of free fatty acids, fatty acid alkyl esters, fatty acid methyl esters, solid Fe-Zn catalysts, transesterification of vegetable oils}, issn = {0926-860X}, doi = {10.1016/j.apcata.2006.08.012}, author = {Sreeprasanth, Pulinthanathu Sree and Srivastava, R. and Srinivas, D. and Ratnasamy, P.} } @article { ISI:000286856600053, title = {Hydrolysis of vegetable oils and fats to fatty acids over solid acid catalysts}, journal = {Applied Catalysis A-General}, volume = {391}, number = {1-2, SI}, year = {2011}, month = {JAN}, pages = {427-435}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Solid Fe-Zn double-metal cyanide (DMC) complexes exhibit high catalytic activity for hydrolysis of edible and non-edible vegetable oils and animal fat. In a batch reaction, complete conversion of vegetable oil triglycerides to fatty acids with selectivity greater than 73 wt\% was obtained at temperatures as low as 463 K, autogenous pressure and with 5 wt\% of catalyst. Catalytic activity of DMC was superior to Amberlyst (TM) 70, SAPO-11, H-beta, HY, MoO(x)/Al(2)O(3) and sulfated zirconia. Rates of hydrolysis were greatly enhanced when solvents (tetrahydrofuran or N,N-dimethylformamide), phase transfer agents (tetrapropyl ammonium bromide) and products (a mixture of mono-/diglycerides and fatty acids) or fatty acid was added to the feed. Surface hydrophobicity which enables high wettability and activation of glycerides on active, acidic sites of reusable DMC is attributed to be the major cause for its superior catalytic activity. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Double-metal cyanide complex, Fat splitting, Fatty acids, Hydrolysis of vegetable oils and fats, solid acid catalyst}, issn = {0926-860X}, doi = {10.1016/j.apcata.2010.03.047}, author = {Satyarthi, J. K. and Srinivas, D. and Ratnasamy, P.} } @article { ISI:000352115600006, title = {Highly active and reusable ternary oxide catalyst for dialkyl carbonates synthesis}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {398}, year = {2015}, month = {MAR}, pages = {42-49}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The application of ternary oxides, prepared through calcination of rare-earth modified Mg/Al-hydrotalcite (HT), as highly active, selective, and reusable solid catalysts for dialkyl carbonates synthesis by transesterification reaction is reported. Dimethyl carbonate, for example, was prepared by reacting ethylene carbonate with methanol in 100 mol\% selectivity at a yield of 95 mol\%. Among several rare-earth modified precursors, La (10 mol\%)-HT showed the highest activity. This catalyst was active even at ambient conditions. Basicity of the catalyst played crucial role on its performance. The activity of these catalysts was superior to the hitherto known solid catalysts for this reaction. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Dialkyl carbonate, Dimethyl carbonate (DMC), Rare-earth modified hydrotalcite, Solid base catalyst, Ternary oxide, Transesterification of cyclic carbonate}, issn = {1381-1169}, doi = {10.1016/j.molcata.2014.11.022}, author = {Unnikrishnan, P. and Srinivas, D.} } @inbook {45859, title = {Heterogeneous catalysis}, booktitle = {Industrial catalytic processes for fine and specialty chemicals}, year = {2016}, pages = {41-111}, publisher = {Elsevier Inc.}, organization = {Elsevier Inc.}, abstract = {A majority of industrial catalytic processes use heterogeneous catalysts because of their engineering advantages. At present, heterogeneous catalysis covers almost 80\% of the global market share. The demand for heterogeneous catalysis is growing annually. In 2010, it was about US 14 billion and expected estimation of it in 2015 is around 20 billion. Understanding at the molecular level the way surfaces of solids catalyze chemical reactions is a challenge in this area of research. This chapter introduces the fundamentals of heterogeneous catalysis, current industrial practices using solid catalysts, reaction steps involved in heterogeneous catalysis, conventional and advanced methods of catalyst preparation, catalyst characterization techniques, causes for catalyst deactivation, steps to avoid deactivation, and methods of catalyst reactivation. }, issn = {978-012801457-8}, doi = {10.1016/B978-0-12-801457-8.00003-3}, author = {Unnikrishnan, P. and Srinivas, D.} }