@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:000340579200011, title = {Synthesis of fatty monoester lubricant base oil catalyzed by Fe-Zn double-metal cyanide complex}, journal = {Journal of Chemical Sciences}, volume = {126}, number = {4}, year = {2014}, month = {JUL}, pages = {997-1003}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

Fatty monoester lubricant base oils as high as 96.7 mol\% were prepared by reacting methyl oleate with long-chain alcohols viz., 2-ethyl-1-hexanol (C-8-OH), 1-decanol (C10OH) and 1-dodecanol (C12OH) in the presence of a solid Fe-Zn double-metal cyanide (DMC) complex catalyst. Unlike many other acid catalysts, DMC doesn{\textquoteright}t produce undesired ether side products. The catalyst was reusable in four recycling experiments with little loss in catalytic activity and ester yield. The long-chain esters prepared in the study have the desired physical properties for their application as lubricant base oils.

}, keywords = {Fatty monoester, Fe-Zn double-metal cyanide (DMC) catalyst, lubricant base oil, transesterification}, issn = {0974-3626}, author = {Raut, Ravindra K. and Shaikh, Mehejabeen and Darbha, Srinivas} } @article {45887, title = {Selective aerobic oxidation of alcohols over Au-Pd/sodium titanate nanotubes}, journal = {Catalysis Communications}, volume = {58}, year = {2015}, month = {JAN }, pages = {149-153}, type = {Article}, abstract = {

catalytic application of Au-Pd nanoparticles supported on sodium titanate nanotubes (NaTNTs) for liquid-phase aerobic oxidation of alcohols is reported, for the first time. This reaction occurs at 80-120 degrees C, 1 atm and solvent-/alkali-free conditions yielding the corresponding carbonyls in high selectivity. This catalyst was reusable and found to be more active/selective than the corresponding monometallic Au and Pd catalysts and Au-Pd/TiO2. Higher dispersion, smaller particle size and higher amount of electron density at gold are the causes for the superior activity of Au-Pd/NaTNT catalyst. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {aerobic oxidation, Alcohol, Bimetallic Au-Pd catalyst, Sodium titanate nanotubes, TiO2}, issn = {1566-7367}, doi = {10.1016/j.catcom.2014.09.018}, author = {Nepak, Devadutta and Darbha, Srinivas} } @article { ISI:000349999200004, title = {Structure-induced catalytic activity of Co-Zn double-metal cyanide complexes for terpolymerization of propylene oxide, cyclohexene oxide and CO2}, journal = {RSC Advances}, volume = {5}, number = {24}, year = {2015}, month = {FEB}, pages = {18196-18203}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The application of Co-Zn double-metal cyanide (DMC) complexes as catalysts for selective terpolymerization of propylene oxide, cyclohexene oxide and CO2 producing polycarbonates is reported for the first time. DMC complexes were prepared with and without using a co-complexing agent. The catalyst with monoclinic/rhombohedral crystal structure and strong Lewis acidity, prepared without using a co-complexing agent showed higher initial activity than that with a cubic structure prepared using a co-complexing agent. Interestingly, no induction period in the terpolymerization reaction was observed. The terpolymer has 75.5 mol\% of carbonate fraction in its composition and an average molecular weight of 22 700 and polydispersity index of 2.97. It is characterized by a T-g of 55 degrees C. This structure-induced catalytic activity of DMC can open up new avenues for its applications in other reactions. The influence of process parameters on the catalytic activity of DMC was investigated.

}, issn = {2046-2069}, doi = {10.1039/c5ra00299k}, author = {Sebastian, Joby and Darbha, Srinivas} } @article {47007, title = {Selective, bifunctional Cu-WOx/Al2O3 catalyst for hydrodeoxygenation of fatty acids}, journal = {Catalysis Science \& Technology}, volume = {10}, year = {2020}, month = {JAN }, pages = {268-277}, type = {Article}, abstract = {

Selective hydrodeoxygenation of oleic acid (OA; in a batch reactor, at 300 degrees C, 30 bar H-2 pressure, reaction time of 1 h and reactant-to-catalyst weight ratio of 2 g OA/0.2 g) forming n-octadecane in yields as high as 93\% over a non-noble metal, sulfur-free, bimetallic Cu-WOx/Al2O3 catalyst is reported for the first time. Several Cu-WOx/Al2O3 compositions were prepared by a sequential wet-impregnation method and evaluated. A catalyst with 10 wt\% Cu and 4 wt\% W enabled the highest activity and selectivity. Upon adding WOx, the amount of moderate and strong acid sites increased and more Cu in the catalyst was in reduced electron-rich metallic (Cu-0) state. The crystallite size and dispersion of Cu were little affected. WOx promoted the fatty acid hydrodeoxygenation activity of Cu. While a monometallic Cu catalyst (10Cu/Al2O3) yielded n-octadecane and n-heptadecane along with high amounts of intermediate octadecanol and octadecanal products, the bimetallic catalyst (10Cu-4WO(x)/Al2O3) gave mainly n-octadecane. Acidity and the high amount of reduced Cu-0 species are responsible for the high catalytic hydrodeoxygenation performance of this bimetallic catalyst.

}, issn = {2044-4753}, doi = {10.1039/c9cy01939a}, author = {Janampelli, Sagar and Sethia, Govind and Darbha, Srinivas} } @article {46897, title = {Solid catalysts for conversion of furfural and its derivatives to alkanediols}, journal = {Catalysis Reviews-Science and Engineering}, volume = {62}, year = {2020}, month = {OCT }, pages = {566-606}, type = {Review}, abstract = {

Alkanediols with five and six carbon atoms (1,2- \& 1,5-pentanediols and 1,2- \& 1,6-hexanediols, respectively) are an important class of industrial chemicals having wide application. Their production from lignocellulosic biomass-derived furfural and its derivatives using solid catalysts is a sustainable and attractive approach. Several bifunctional catalysts with metal (for hydrogenation/hydrogenolysis) and acid/base (for ring opening) functionalities have been reported. Effective and selective conversion of furfurals to a desired diol is still a challenge. This review discusses the recent advances in catalyst development for pentane- and hexanediols. The reaction pathways, active sites, and possible reaction mechanisms over the solid catalysts are discussed. A comparative catalytic activity data of the known catalysts are reported.

}, keywords = {5-hydroxymethylfurfural (HMF), Alkanediol, furfural (FAL), hexanediol, pentanediol, solid catalyst}, issn = {0161-4940}, doi = {10.1080/01614940.2020.1744327, Early Access Date = APR 2020}, author = {Enjamuri, Nagasuresh and Darbha, Srinivas} } @article {47309, title = {Selective deoxygenation of fatty acids to fuel-range hydrocarbons over Pt-MOx/ZrO2 (M = Mo and W) catalysts}, journal = {Catalysis Today}, volume = {375}, year = {2021}, month = {SEP}, pages = {174-180}, type = {Article}, abstract = {

A comparative catalytic activity study of Pt-MoOx/ZrO2\ and Pt-WOx/ZrO2\ for deoxygenation of oleic acid (OA) forming fuel-range, linear hydrocarbons is reported. These catalysts (with 4 wt\% Pt and 8 wt\% Mo or W) were prepared by a sequential wet-impregnation method and characterized for the structural and electronic properties. Pt-MoOx/ZrO2\ showed higher catalytic activity than Pt-WOx/ZrO2. Hydrodeoxygenation was the selective pathway over these bifunctional catalysts yielding n-octadecane. High conversion of OA was achieved at 200 {\textdegree}C itself. On the contrary, monometallic Pt/ZrO2\ was weakly active. It was selective mainly toward decarboxylation/decarbonylation producing n-heptadecane. Higher amounts of Pt and metal oxide in reduced forms are responsible for the high hydrodeoxygenation activity and selectivity of these reusable, bimetallic catalysts.

}, doi = {10.1016/j.cattod.2020.04.020}, author = {Janampelli, Sagar and Darbha, Srinivas} }