Flash pyrolysis temperature effects

The volatilization of arsenic during the thermal destruction of CCA-treated wood may be reduced by utilizing low-temperature pyrolysis. Low-temperature pyrolysis uses temperatures of approximately 300-400 °C with a limited air supply (Helsen and Van den Bulck, 2004, 286, 290 Helsen and Van den Bulck, 2003). Pyrolysis includes slow and flash methods (Helsen and Van den Bulck, 2004). Flash pyrolysis, which produces an oil byproduct, is not effective with CCA-treated wood because only 5-18% of the arsenic... 

Figure 23.7 The temperature effects on product phase yields of PS. (Reproduced from Journal of Analytical and Applied Pyrolysis, 60 (2), A. Karaduman, Flash pyrolysis of polystyrene wastes in a free-fall reactor under vacuum, 179-186(2001), with permission from Elsevier)...

Karaduman [80] investigated the effects of temperature on the yields in flash pyrolysis of PE. The gas yield continued to increase with temperature. The yield of liquid products and the total conversion rate also kept increasing up to a certain temperature, but after this point, began to fall slowly due to partial decomposition of the expected products. The yield of solid residue decreased with the increase of temperature. 

The fact that most flash pyrolysis studies have used radiant heating suggests solar heat as a natural means for effecting flash pyrolysis of biomass feedstocks. Since solar radiation has a characteristic temperature of almost 6000°K, it can be used to achieve very rapid heating of opaque, solid particles. Earlier studies (2) have shown that the quantity of heat required for biomass gasification is small less than 1 Gj per Mg of dry solid... 

Pyrolysis with in situ methylation in the presence of TMAH is now commonly applied for the structural investigation of HS. It has been reported, however, that TMAH not only methylates polar pyrolysate but also assists in bond cleavage. For example, TMAH was found as effective at 300°C as at 700°C for the production of some volatile products from HS, indicating that pyrolysis occurs with equal effectiveness at subpyrolysis temperature of 300°C. It is believed that TMAH pyrolysis is actually a thermally assisted chemolysis rather than pure pyrolysis and it can cause hydrolytic ester and ether bond cleavage even at lower temperature, resulting in some unwanted side reactions, e.g., artificial formation of carboxylic groups from aldehydes. Therefore, TMAH thermochemolysis at low temperature, e.g., 300°C has been proposed. This technique offers several advantages over classical flash pyrolysis or preparative pyrolysis apparatus " ... 

Many rDA reactions are carried out at temperatures of 150 C or more in solution phase and often at temperatures of 400-600 C using the flash vapor pyrolysis (FVP) method individual conditions are referenced throughout the text. However, an accelerating effect by anionic, cationic and radical substimtion on either the dienophile or at the termini of the diene fragments has been predicted by Carpenter.Experimentally, this prediction has been substantiated only for anionic substitution. In 1967, Hart reported what is likely the first example of an oxyanion-accelerated rDA reaction. Both oxyanionic " and car-banionic substituents accelerate the cycloreversion reaction such that they proceed rapidly at room temperature (for example, equation 3). In addition, acid-catalyzed rDA reactions have been reported in which protonation effectively makes the dienophile fragment of the adduct more electron deficient. Grieco has utilized a room temperature retro aza DA reactitm useful for the N-methylation of dipeptides and amino acid derivatives (equatitm 4). ... 

Flash, vacuum pyrolysis . The contact times are shorter here than under our conditions, resulting in a lower effective temperature. 

The stability of the pyrazolinone tautomers was related to their scale of aromaticity.Experimental values for the tautomerism of pyrazolinone derivatives were obtained by flash vacuum pyrolysis (FVP), which allowed the calculation of the effect of the temperature on the equilibrium between tautomers. The variation of Kj with the temperature was determined by H NMR in solution for the model compound l-phenyl-3-methyl-2-pyrazolin-5-one (Scheme 25), showing that at 0 K the only tautomers present are either the NH or the OH ones. Temperature and solvent effects on the prototropic equilibrium of the model compound in solution showed that... 

Scrap butyl rubber inner tubes represent a source of waste rubber that is easily identified and segregated. Workers in Pakistan [19] have subjected these items to a batch non-oxidative pyrolysis process under both uncatalysed and catalysed conditions. In both cases atmospheric pressure was used, with zinc oxide being used as the catalyst in the catalysed version. The resultant product in both cases consisted of a hydrocarbon mixture and carbon black. The effects of temperature, amount of zinc oxide and reaction time on the yield of the products were studied. The hydrocarbon fraction was assessed as a fuel by carrying out tests such as flash point and aniline point. 

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