Fe Catalyst (fe + catalyst)

Distribution by Scientific Domains

Selected Abstracts

Introducing a Flat Model of the Silica-Supported Bis(imino)pyridyl Iron(II) Polyolefin Catalyst

Wei Han
Abstract Summary: A well-defined flat model of a supported homogeneous polyolefin catalyst is prepared on the basis of an immobilized bis(imino)pyridyl iron complex on a super flat silica surface. The amount of supported catalyst precursor is quantified using XPS. This model catalyst remains active over extended periods, i.e., an average activity of 0.25,×,103 kg PE,·,(molCat,·,h,·,bar),1 is obtained for 24 h of ethylene polymerization. The morphology of the nascent polyethylene film is investigated by SEM. A side-view SEM image of the PE produced from the supported bis(imino)pyridyl Fe catalyst. [source]

Kinetic modeling study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

AICHE JOURNAL, Issue 2 2009
R. Philippe
Abstract The kinetic and physical laws developed in the first part of the study have been implemented in a modified version of the bubbling bed Kato and Wen model to represent multiwalled carbon nanotubes (MWCNTs) synthesis by catalytic chemical vapor deposition from ethylene as carbon source and using an Fe/Al2O3 catalyst. The absolute deviation for MWCNT productivity between experimental results of Part 1 and simulations is of 17.3% when only considering experiments for which the bed is mainly in bubbling regime. The influence of the main operating parameters on the evolutions with time of the species molar fractions, the weight of MWCNTs formed, and the bed characteristics has been numerically studied. Such capabilities can help designing new reactors. Finally, the model has been used for scale up purposes, by increasing the reactor diameter and catalyst weight. Simulations have shown that the process productivity could reach 74 tons/year of MWCNTs in a reactor 45 cm in diameter. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source]

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

AICHE JOURNAL, Issue 2 2009
R. Philippe
Abstract Multi-walled carbon nanotubes (MWCNTs) have been produced with high selectivity by fluidized bed catalytic chemical vapor deposition from ethylene on Fe/Al2O3 catalysts. The influence of operating parameters such as deposition duration, temperature, ethylene and hydrogen partial pressures, and iron loading on MWCNT productivity, process selectivity, characteristics of final powders, and chemical composition of the outlet gases has been analyzed. Using gas phase chromatography, methane and ethane have been detected, whatever are the conditions used. Between 650 and 750°C, no catalyst deactivation occurs because nucleation remains active all along the synthesis, thanks to the explosion of the catalyst grains. Above 650°C, ethane itself produces MWCNTs, whereas methane does not react in the temperature range, 550,750°C. The formation of MWCNTs induces marked bed expansions and sharp decreases of grain density. Apparent kinetic laws have been deduced from the collected data. The apparent partial orders of reaction for ethylene, hydrogen, and iron were found to be 0.75, 0, and 0.28, respectively. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source]

A novel continuous reactor for catalytic reduction of NOx,fixed bed simulations

Terris T. Yang
Abstract A novel dual-zone fluidized bed reactor was proposed for the continuous adsorption and reduction of NOx from combustion flue gases. The adsorption and reaction behaviour of such a reactor has been simulated in a fixed bed reactor using Fe/ZSM-5 catalyst and propylene reductant with model flue gases. Fe/ZSM-5 exhibited acceptable activity at T,=,350°C and GHSV,=,5000 h,1 when O2 concentration was controlled at levels lower than 1% with a HC to NO molar ratio of about 2:1. XPS and BET surface area measurement revealed the nature of the deactivation of the catalyst. Those performance data demonstrated the feasibility of a continuous dual-zone fluidized bed reactor for catalytic reduction of NOx under lean operating conditions. Un nouveau réacteur à lit fluidisé à double zone est proposé pour l'adsorption et la réduction en continu de NOx à partir de gaz de carneau de combustion. Le comportement d'adsorption et de réaction d'un tel réacteur a été simulé dans un réacteur à lit fixe utilisant un catalyseur Fe/ZSM-5 et un agent réducteur avec des gaz de carneau modèle. Le Fe/ZSM-5 montre une activité acceptable à T,=,350°C et GHSV,=,5000 h,1 lorsque la concentration d'O2 est contrôlée à des niveaux inférieurs à 1% avec un rapport molaire HC,NO d'environ 2:1. La mesure de surface par XPS et BET a permis de caractériser la désactivation du catalyseur. Ces données de performance illustre la faisabilité du réacteur à lit fluidisé à double zone Fe/ZSM-5 pour la réduction catalytique de NOx dans des conditions opératoires pauvres. [source]