Metal-Free Synthesis of Carbon Nanotubes Filled with Calcium Silicate
by Jiangtao Zhu
A new metal-free catalyst CaSiO3 was developed to grow carbon nanotubes (CNTs) on a pyrolytic graphite paper tape by... more A new metal-free catalyst CaSiO3 was developed to grow carbon nanotubes (CNTs) on a pyrolytic graphite paper tape by an ethanol catalytic chemical vapor deposition method at 1200-1400 oC. The prepared CNTs with a droplet tip had a multi-walled structure and were filled with amorphous CaSiO3. Temperature, determining the melting of CaSiO3, was critical for the growth of the CNTs. This new catalyst is suggested to follow the similar roles of transition metals in the growth of CNTs by a molten state to absorb carbon and form CNTs after reaching saturation.
Download (.pdf) Iron catalysts for the growth of carbon nanofibers: Fe, Fe3C or both?
Chem. Mater., 23(24), 5379–5387 (2011)
DOI: 10.1021/cm202315j
Iron is a widely used catalyst for the growth of carbon nanotubes (CNTs)/carbon nanofibers (CNFs) by catalytic... more Iron is a widely used catalyst for the growth of carbon nanotubes (CNTs)/carbon nanofibers (CNFs) by catalytic chemical vapour deposition. However, both Fe and Fe-C compounds (generally, Fe3C) have been found to catalyze the growth of CNTs/CNFs, and a comparison study of their respective catalytic activities is still missing. Furthermore, the control of the crystal structure of iron-based catalysts, that is α-Fe or Fe3C, is still a challenge, which not only obscures our understanding of the growth mechanisms of CNTs/CNFs, but also complicates subsequent procedures, such as the removal of catalysts for better industrial applications. Here, we show a partial control of the phase of iron catalysts (α-Fe or Fe3C), obtained by varying the growth temperatures during the synthesis of carbon-based nanofibers/nanotubes in a plasma-enhanced chemical vapour deposition reactor. Moreover, we directly compare the growth rates of carbon-based nanofibers/nanotubes during the same experiments and find that CNFs/CNTs grown by α-Fe nanoparticles are longer than CNFs/CNTs grown from Fe3C nanoparticles. The influence of the type of catalyst on the growth of CNFs is analyzed and the corresponding possible growth mechanisms, based on the different phases of the catalysts, are discussed.
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A Highly Active Catalyst for Huisgen 1,3-Dipolar Cycloadditions Based on the Tris(triazolyl)methanol-Cu(I) Structure
A new tris(1-benzyl-1H-1,2,3-triazol-4-yl)methanol ligand 3 has been prepared by a triple Cu(I)-catalyzed alkyne−azide... more A new tris(1-benzyl-1H-1,2,3-triazol-4-yl)methanol ligand 3 has been prepared by a triple Cu(I)-catalyzed alkyne−azide 1,3-dipolar cycloaddition (CuAAC). Ligand 3 forms a stable complex with CuCl, which catalyzes the Huisgen 1,3-dipolar cycloaddition on water or under neat conditions. Low catalyst loadings, short reaction times at room temperature, and compatibility with free amino groups make 3·CuCl an outstanding catalyst for CuAAC.
Low-Temperature Pyrolysis and Gasification of Biomass: Numerical Evaluation of the Process Intensification Potential of Rotating- and Circulating Rotating Fluidized Beds in a Static Fluidization Chamber
Nicolas Staudt, Université catholique de Louvain
Axel De Broqueville, Independent Researcher
Waldo Rosales Trujillo, Université catholique de Louvain
Juray De Wilde, Universite catholique de Louvain
The process intensification potential of rotating- and circulating rotating fluidized beds in a static fluidization... more The process intensification potential of rotating- and circulating rotating fluidized beds in a static fluidization chamber when used for the low-temperature pyrolysis and gasification of biomass is numerically evaluated. The species continuity equations and energy balance equations are based on complete mixing for the particles within given zones of the particle bed and plug flow for the gas. The reaction mechanism accounts for pyrolysis of biomass and tar, gas-phase combustion, the water gas shift reaction, and combustion and gasification of char. A comparison with current circulating fluidized bed riser technology is made. The circulation of inert solid with a high heat capacity and the separation of the flue gas from the production gas are also studied.
RESEARCH ARTICLES
19. High Surface Area Silica Nanospheres with Unprecedented Fibrous Morphology (HOT article) (Front Cover).
Vivek Polshettiwar*, D. Cha, X. Zhang and J. M. Basset,* Angew. Chem. Int. Ed. 2010, 49, 9652-9656.
20. Chemistry by Nano-Catalysis: First Example of a Solid-Supported RAPTA Complex for Challenging Organic Reactions in Aqueous Medium.
E. García-Garrido, J.Francos, V. Cadierno,* J.M. Basset,* V. Polshettiwar,* Chem. Sus.Chem, 2010, in press.
21. Nano ferrites for water splitting: Unprecedentedly high photocatalytic hydrogen production under visible light
Priti A. Mangrulkar, Vivek Polshettiwar,* R. S. Varma, S. S. Rayalu,* MS under preparation.
22. “Hydro-metathesis” of olefins: A new catalytic reaction with a bifunctional single-site catalyst Ta-H/KCC.1.
V. Polshettiwar,* Jean Thivolle-Cazat,* J. M. Basset,* Angew. Chem. Int. Ed. 2011, 50, in press.
23. Tantalum Hydride (TaH) on MCM-41 for Efficient Hydrogenolysis of Alkanes: Low Temperature Conversion of Alkanes into Lower Carbon Number Alkanes at Atmospheric Pressure.
V. Polshettiwar, Jean Thivolle-Cazat,* J. M. Basset,* MS under preparation.
24. Nano-organocatalyst: Magnetically retrievable ferrite-anchored glutathione for microwave-assisted Paal-Knorr reaction, Aza-Michael addition and pyrazole synthesis. (SYN FACT)
Vivek Polshettiwar* and R. S. Varma, Tetrahedron 2010, 66, 1091-1097.
25. Nanoparticle-supported and magnetically recoverable ruthenium hydroxide catalyst: Efficient hydration of nitriles to amides in aqueous medium.
Vivek Polshettiwar* and R. S. Varma, Chem. Eur. J. 2009, 15, 1582-1586.
26. Magnetic nanoparticle-supported glutathione: a conceptually sustainable organocatalyst.
Vivek Polshettiwar*, Babita Baruwati, and R. S. Varma, Chem.Commun. 2009, 1837-1839.
27. Revisiting the Meerwein–Ponndorf–Verley reduction: a sustainable protocol for transfer hydrogenation of aldehydes and ketones.
Vivek Polshettiwar* and R. S. Varma, Green Chem. 2009, 11, 1313-1316.
28. Self-assembly of metal oxides into 3D nano-structures: Synthesis and nano-catalysis. (TOP 5)
Vivek Polshettiwar*, Babita Baruwati, and R. S. Varma, ACS Nano 2009, 3, 728-736.
29. Nanoparticle-supported and magnetically recoverable palladium (Pd) catalyst: A selective and sustainable oxidation protocol with high turnover number.
Vivek Polshettiwar and R. S. Varma, Org. Biomol. Chem. 2009, 7, 37-40.
30. Nanoparticle-supported and magnetically recoverable Nickel catalyst: A robust and economic hydrogenation and transfer hydrogenation protocol.
Vivek Polshettiwar*, B. Baruwati, & R. S. Varma, Green Chem. 2009, 11, 127-131.
31. Glutathione promoted expeditious green synthesis of silver nanoparticles using microwaves.
Babita Baruwati, Vivek Polshettiwar and R. S. Varma, Green Chem. 2009, 11, 926-930..
32. Self-assembly of palladium (Pd) nanoparticles: Synthesis of Pd nanobelts, nanoplates and nanotrees using vitamin B1 and their application in carbon-carbon coupling reactions
M. N. Nadaguada, Vivek Polshettiwar, and R. S. Varma, J. Mat. Chem. 2009, 19, 2026–2031.
33. Ruthenium hydroxide supported on magnetic nanoparticles: a benign aqueous protocol for hydration of nitriles.
Vivek Polshettiwar* and R. S. Varma, NATURE Protocol 2009, DOI: 10.1038/nprot.2009.103
34. Magnetically recoverable supported ruthenium catalyst for hydrogenation of alkynes and transfer hydrogenation of carbonyl compounds.
Babita Baruwati, Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2009, 50, 1215-1218.
35. Microwave-Assisted Transformations and Synthesis of Polymer Nanocomposites and Nanomaterials.
M.N. Nadagouda, Vivek Polshettiwar and R.S. Varma: Am. Chem. Soc. Polymer Preprints, 2008, 49, 947.
36. Synthesis of single-crystal micro-pine structured nano-ferrites and their application in catalysis.
Vivek Polshettiwar, M. N. Nadaguada and R. S. Varma, Chem. Commun. 2008, 6318-6320.
37. Olefin ring closing metathesis and hydrosilylation reaction in aqueous medium by Grubbs second generation ruthenium catalyst.
Vivek Polshettiwar and R. S. Varma, J. Org. Chem. 2008, 73, 7417-7419.
38. Tandem bis-aldol reaction of ketones: a facile one pot synthesis of 1,3-dioxanes in aqueous medium.
Vivek Polshettiwar and R. S. Varma, J. Org. Chem. 2007, 72, 7420-7422.
39. Magnetically recoverable supported ruthenium catalyst for hydrogenation of alkynes and transfer hydrogenation of carbonyl compounds.
Babita Baruwati, Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2009, 50, 1215-1218.
40. Ring-fused aminals: Catalyst and solvent-free microwave-assisted -amination of nitrogen heterocycles.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2008, 49, 7165-7167.
41. Pd-N-heterocyclic carbene (NHC) organic silica: synthesis and application in C-C coupling reactions.
Vivek Polshettiwar and R. S. Varma, Tetrahedron 2008, 64, 4637-4643.
42. Greener and rapid access to bio-active heterocycles: room temperature synthesis of pyrazoles and diazepines in aqueous medium.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2008, 49, 397-400.
43. Greener and rapid access to bio-active heterocycles: one-pot solvent-free synthesis of 1,3,4-oxadiazoles and 1,3,4-thiadiazoles.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2008, 49, 879-883.
44. Nafion®-catalyzed MW-assisted Ritter reaction: an atom-economic solvent-free synthesis of amides.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2008, 49, 2661-2664.
45. Tandem bis-aza-Michael addition reaction of amines in aqueous medium promoted by PSSA.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2007, 48, 8735-8738.
46. PSSA catalyzed greener synthesis of hydrazones in aqueous medium using microwaves.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2007, 48, 5649-5652.
47. Biginelli reaction in aqueous medium: a greener and sustainable approach to substituted 3,4-dihydropyrimidin-2(1H)-ones.
Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2007, 48, 7343-7346.
48. Expeditious oxidation of alcohols to carbonyl compounds using iron(III) nitrate.
V. V. Namboodiri, Vivek Polshettiwar and R. S. Varma, Tetrahedron Lett. 2007, 48, 8839-8842.
49. An efficient & chemoselective Cbz-protection of amines using silica–sulfuric acid at room temperature.
M. B. Gawande, V. Polshettiwar R. S. Varma, R. V. Jayaram, Tetrahedron Lett. 2007, 48, 8170-8173.
50. Palladium containing nano-structured silica functionalized with pyridine sites: a versatile heterogeneous catalyst for Heck, Sonogashira and cyanation reactions.
Vivek Polshettiwar, Peter Hesemann, Joel J. E. Moreau, Tetrahedron 2007, 63, 6784-6790.
51. Silica hybrid material containing Pd-NHC complex as heterogeneous catalyst for Heck reactions.
Vivek Polshettiwar, Peter Hesemann, Joel Moreau, Tetrahedron Lett. 2007, 48, 5363-5366.
52. Highly ordered functional organosilica by template directed hydrolysis-polycondensation using chiral camphorsulfonamide precursors: Synthesis and application of new task specific ionic liquid.
B. Gadenne, Peter Hesemann, Vivek Polshettiwar and Joel Moreau, Eur. J. Inorg. Chem. 2006, 3697-3702.
53. Alumina encapsulated phosphorus pentasulfide mediated efficient thionation of long chain amides.
Vivek Polshettiwar, and M. P. Kaushik, Tetrahedron Lett. 2006, 47, 2315-2317.
54. Pd(OAc)2/silica in ionic liquid: green Heck catalyst.
V. Polshettiwar, Res. J. Chem. Environ. 2006, 10, 91.
55. N-Octyl quinolinium tribromide: a quinoline based ionic liquid as a new brominating agent for bromination of phenols, amines, alkenes, alkynes.
Vivek Polshettiwar, M. P. Kaushik, Ind. J. Chem. B 2006, 45, 2542.
56. MW enhanced chemistry of CsF-Celite: efficient catalyst for synthesis of esters, ethers, their thio-analogues.
Vivek Polshettiwar and M. P. Kaushik, Catalysis Commun. 2005, 6, 191-194.
57. Tighter ion pair effect and Scale-Up study in microwaves assisted aminolysis of enolizable esters using potassium tert-butoxide (t-BuOK).
Vivek Polshettiwar and M. P. Kaushik, Ind. J. Chem. B, 2005, 44, 773.
58. A new, efficient and simple method for the thionation of ketones to thioketones using P4S10/Al2O3.
Vivek Polshettiwar and M. P. Kaushik, Tetrahedron Lett. 2004, 45, 6255-6257.
59. CsF-Celite catalyzed regio- and chemoselective SN2 type ring opening of epoxides with thiol.
Vivek Polshettiwar and M. P. Kaushik, Catalysis Commun. 2004, 5, 515-518.
60. Phosphorus pentasulfide (P4S10),
Vivek Polshettiwar, Synlett. 2004, 2245-2246.
61. Thionation of carbonyl compounds by phosphorus pentasulfide and HMDO under MW irradiations.
Vivek Polshettiwar, M. Nivsarkar, D. Pardashani and M. P. Kaushik, J. Chem. Res. 2004, 474-476.
62. A new reagent for the efficient synthesis of disulfides from alkyl halides.
Vivek Polshettiwar, M. Nivsarkar, J. Acharya and M. P. Kaushik, Tetrahedron Lett. 2003, 44, 887-889.