Carbon deposition chemical reactors

Chemical vapor deposition (CVD) of carbon from propane is the main reaction in the fabrication of the C/C composites [1,2] and the C-SiC functionally graded material [3,4,5]. The carbon deposition rate from propane is high compared with those from other aliphatic hydrocarbons [4]. Propane is rapidly decomposed in the gas phase and various hydrocarbons are formed independently of the film growth in the CVD reactor. The propane concentration distribution is determined by the gas-phase kinetics. The gas-phase reaction model, in addition to the film growth reaction model, is required for the numerical simulation of the CVD reactor for designing and controlling purposes. Therefore, a compact gas-phase reaction model is preferred. The authors proposed the procedure to reduce an elementary reaction model consisting of hundreds of reactions to a compact model objectively [6]. In this study, the procedure is applied to propane pyrolysis for carbon CVD and a compact gas-phase reaction model is built by the proposed procedure and the kinetic parameters are determined from the experimental results. 

For the chemical reactor, the researchers used a nanoparticle catalyst deposited on metallic micro-structured foils. They tested Cu/ZnO and Pd/ZnO catalysts deposited on the microstructured foils. The Cu/ZnO catalyst was more active than the Pd/ZnO catalyst and had a lower selectivity to undesired carbon monoxide. However, because the Pd/ZnO catalyst was more stable, it was selected for use in their fuel processor. The Pd/ZnO carbon monoxide selectivity of the powder catalyst pressed into a pellet was lower than that of the nanoparticle catalyst deposited on the microstructured foils. This effect was attributed to contact phases between the catalyst and the metal foils. ... 

Stockpiling, transporting, and depositing clean, washed soil product fraction temporarily Dirty washwater treatment process (usually a treatment train including clarifiers, chemical reactors, filter, carbon contractors, dewatering presses, tanks, etc.)... 

Olefin alkylation, long carried out in solution with Bronsted acids, is now beginning to turn to the use of zeolites or other solid acid reagents under mild conditions. The main problem is removal of both the heat generated by the reaction and the carbon deposits. While the former problem can be solved by slurry reactor techniques, the latter requires a chemical treatment which is best carried out by metal-catalyzed hydrogenation at high temperature. 

A combination of controlled atmosphere electron microscopy and flow reactor techniques have been used to investigate the influence of hydrogen sulfide on the catalytic activity of cobalt. Changes in the behavior of cobalt were monitored by the use of probe reactions which are sensitive to the chemical nature of the catalyst surface. These included graphite gasification in oxygen and hydrogen, and carbon deposition from decomposition of hydrocarbons. 

The most simple methods for preparation of hafnium carbide and its composites are the follows. The powder of HfO was thermally treated with Mg in molar ratio 5 4 under a CH flow ranging from 800 to 950 °C [4]. The effective high temperature coating for carbon fiber reinforced carbon and carbon fibre reinforced silicon carbide was prepared with use of HfC [5]. For this purpose hafnium carbide layers were obtained in a thermally simulated chemical vapor deposition (CVD) reactor on nonporous substrates by reaction of hafnium tetrachloride, methane and addition of hydrogen (Eq. 10.1) ... 

The multiwalled nanotubes as well as the herringbone type carbon nanofibers were synthesized in-house in a quartz glass fluidized bed reactor via chemical vapor deposition (CVD). The method is described in detail elsewhere.19 The platelet nanofibers, in contrast, were purchased from the company FutureCarbon GmbH (Bayreuth, Germany). 

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