Fluidising Degradation

The catalytic degradation of HDPE and PP was carried out in a powder-particle fluidised bed with an inside diameter of 25 mm. Two catalysts were used as the medium fluidisation particles. These were F9 (with a composition of silica alumina sodium oxide of 32 48 20 wt.percent) and silica/alumina (SA, with a composition of silica alumina of 71 29 wt.percent). Liquid fuel was produced in high yield. SA produced a higher yield of liquid fuel nd a more valuable gas product between temperatures of400-550C. Over 86 wt.percent conversion... 

Alberici et al. [226] used two forms of reactor to analyse the breakdown of TCE—fixed bed and fluidised bed. In the presence of 20% O2 the main breakdown products identified using GC-MS were phosgene, carbon tetrachloride, dichloroacetyl chloride, dichloroacetic acid and pentachloroethane. In the absence of oxygen the products detected were pentachloroethane, 1-pentachloropropene and 1,1,3,4-tetrachloro-l,3-butadiene. Kim et al. [230] concluded that the degradation rate of TCE decreased with increasing water vapour. They concluded that there was an optimum water concentration of 0.383 mol m-3 (vol%). It was also reported that molecular oxygen was an essential component because it trapped photogenerated electrons on the semiconductor surfaces and decreased the recombination of electrons and holes [230]. 

The influence of small amounts of PVC degrading in PET scrap during reprocessing has been studied (371). An aqueous column flotation technique, utilising pH level and surfactants, has been proposed (311). A continuous thermal separation system, for removal of trace PVC, has also been described (204). Triboelectrostatic separation, based on cyclones, fluidised beds or rotating tubes, has also separated five commonly used plastics, including PVC (30). 

A. A. Garforth, Y.-H. Lin, P. N. Sharratt, P. N. and J. Dwyer Production of Hydrocarbons by Catalytic Degradation of High-Density Polyethylene in a Laboratory Fluidised-Bed Reactor. Appl. Catal. A, 169, 331 (1998). 

M. Predel and W. Kaminsky Pyrolysis of Mixed Polyolefins in a Fluidised-Bed Reactor and on a Pyro-GC/MS to Yield Aliphatic Waxes. Polym. Degrad. Stabil, 70, 373 (2000). 

W. Kaminsky, M. Predel and A. Sadiki, Feedstock recycling of polymers by pyrolysis in a fluidised bed. Polymer Degradation and Stability, 85, 1045-1050, (2004). 

Smolders K, Baeyens J. Thermal degradation of PMMA in fluidised beds. Waste Manag 2004 24 (8) 849-857. 

Yoshioka, T. Grause, G. Eger, C. Kaminsky, W. Okuwaki, A. Pyrolysis of Poly(ethylene terephthalate) in a Fluidised Bed Plant. Polym. Degrad. Stab. 2004, 86, 499-504. 

Studies on thermal degradation of PE have reported hydrogen production in the fluidised-bed pyrolysis of a low-density polyethylene (LDPE) [a.54]. Hydrogen may be produced from the polymer melt and/or from thermal dehydrogenation of volatile products in the gas phase as a secondary reaction at the reactor temperature. From the results, it seems more possible that hydrogen is formed in the polymer melt, because, if more hydrogen were produced from thermal dehydrogenation of volatile products in the gas phase, increased... 

Couto, S. R. Dominguez, A. Sanroman, A. Photocatalytic degradation of dyes in aqueous solution operating in a fluidised bed reactor. Chemosphere 2002, 46, 83-86. 

---