Importance of fundamental sp, sp2, and sp3 hydrocarbon radicals in the growth of polycyclic aromatic hydrocarbons.

The most basic chemistry of products formation in hydrocarbons pyrolysis has been explored via a comparative experimental study on the roles of fundamental sp, sp(2), and sp(3) hydrocarbon radicals/intermediates such as ethyne/ethynyl (C(2)H(2)/C(2)H), ethene/ethenyl (C(2)H(4)/C(2)H(3)), and methane/methyl (CH(4)/CH(3)) in products formations. By using an in situ time-of-flight mass spectrometry technique, gas-phase products of pyrolysis of acetylene (ethyne, C(2)H(2)), ethylene (ethene, C(2)H(4)), and acetone (propanone, CH(3)COCH(3)) were detected and found to include small aliphatic products to large polycyclic aromatic hydrocarbons (PAHs) of mass 324 amu. Observed products mass spectra showed a remarkable sequence of mass peaks at regular mass number intervals of 24, 26, or 14 indicating the role of the particular corresponding radicals, ethynyl (C(2)H), ethenyl (C(2)H(3)), or methyl (CH(3)), in products formation.

Novel products from C6H5 + C6H6/C6H5 reactions.

To date only one product, biphenyl, has been reported to be produced from C(6)H(5) + C(6)H(6)/C(6)H(5) reactions. In this study, we have investigated some unique products of C(6)H(5) + C(6)H(6)/C(6)H(5) reactions via both experimental observation and theoretical modeling. In the experimental study, gas-phase reaction products produced from the pyrolysis of selected aromatics and aromatic/acetylene mixtures were detected by an in situ technique, vacuum ultraviolet (VUV) single photon ionization (SPI) time-of-flight mass spectrometry (TOFMS).

Fractionation of single wall carbon nanotubes by length using cross flow filtration method.

A novel system for fractionating single wall carbon nanotubes (SWCNTs) by length via a three-step cross-flow filtration has been developed in which three membrane filters of different pore sizes, 1.0, 0.45, and 0.

A highly efficient growth mechanism of polycyclic aromatic hydrocarbons.

A highly efficient growth mechanism of polycyclic aromatic hydrocarbons (PAHs) initiated and accelerated by phenyl radicals has been investigated on the basis of kinetic analysis of gas phase reaction products of pyrolysis of benzene with and without addition of acetylene and acetylene only. Pyrolytic reactions were performed in a flow tube reactor and the resulting products were detected by an in situ direct sampling mass spectrometric technique using a vacuum ultraviolet (VUV) single photon ionization (SPI) time of flight mass spectrometry (TOFMS). The detected species varies from smaller to larger PAHs up to m/z = 454 (C(36)H(22)) including primary PAHs, polyphenyl-PAHs and cyclopentafused-PAHs (CP-PAHs).

Role of methyl radicals in the growth of PAHs.

The role of methyl radicals in the networking of sp(2) carbons has been explored through kinetic analysis of mass spectra of the gas-phase products of the pyrolysis of toluene and toluene/acetone mixtures. Pyrolytic reactions were performed in a flow tube reactor at temperatures of 1140-1320 K and a constant total pressure of 10.38 Torr with a residence time of 0.

An efficient carbon precursor for gas phase growth of SWCNTs.

The sp(2) C(2) species, C(2)H(3)/C(2)H(4), has been found as a key precursor for the efficient growth of single-wall carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD) from hydrocarbons.

Role of phenyl radicals in the growth of polycyclic aromatic hydrocarbons.

To investigate the role of phenyl radical in the growth of PAHs (polycyclic aromatic hydrocarbons), pyrolysis of toluene with and without benzene has been studied by using a heatable tubular reactor couple with an in-situ sampling vacuum ultraviolet (VUV) single photon ionization (SPI) time-of-flight mass spectrometer (TOFMS) at temperatures 1155-1467 K and a pressure of 10.02 Torr with 0.56 s residence time.

In situ direct sampling mass spectrometric study on formation of polycyclic aromatic hydrocarbons in toluene pyrolysis.

The gas-phase reaction products of toluene pyrolysis with and without acetylene addition produced in a flow tube reactor at pressures of 8.15-15.11 Torr and temperatures of 1136-1507 K with constant residence time (0.