Pyrolysis, slow products

To illustrate the combined effects of the activation energy and frequency factor on the rate of the particular pyrolysis step, the values were calculated for the samples K and KOR at several temperatures in the region 723-823 K (450-550 °C). Comparison of the results demonstrates that at 723 K, for the sample K is two orders of magnitude lower than for sample KOR. This implies relatively slow production of the intermediate B2... 

Pyrolysis entails thermal decomposition of biomass molecules in the absenee of oxygen, usually at the temperatures up to 650-800 K. To produee liquid oils, the heating process should be short [i.e., short residenee time), thus this process is usually referred to as fast pyrolysis. At high temperature, the biomass is vaporized and then condensed upon cooling to produce a liquid oil mixture which may be comprised of more than 300 compounds such as alkanes, aromatic aliphatic, sugars, alcohols, ketones, aldehydes, acids and esters. If the residence time is longer (slow pyrolysis), the product mixture is likely to produce more solid coke than liquid fuels. An advantage of fast pyrolysis is that it is economical for use on a small scale ie., 50-100 tons biomass per day). Yields of bio-oil production in excess of 70% have been... 

Conventional pyrolysis (slow pyrolysis), proceeds under a low heating rate with solid, liquid and gaseous products in significant portions [16,18]. It is an ancient process used mainly for charcoal production. Vapours can be continuously removed as they are formed. 

Biochar from dairy manure also has pofenfial for environmenfal remediation or for creating slow release phosphorus fertilizers (Cau and Harris, 2010). Dairy manure was converted by heating at temperatures below pyrolysis temperatures (< 500 °C) and in the presence of air. The potential benefit for lowering GHGs was nof defermined but the products have the potential of creating new markets for manure. 

The question of the stability of the biomolecules is a vital one. Could they really have survived the tremendous energies which would have been set free (in the form of shock waves and/or heat) on the impact of a meteorite Blank et al. (2000) developed a special technique to try and answer this question. They used an 80-mm cannon to produce the shock waves the shocked solution contained the two amino acids lysine and norvaline, which had been found in the Murchison meteorite. Small amounts of the amino acids survived the bombardment , lysine seeming to be a little more robust. In other experiments, the amino acids aminobutyric acid, proline and phenylalanine were subjected to shock waves the first of the three was most stable, the last the most reactive. The products included amino acid dimers as well as cyclic diketopiperazine. The kinetic behaviour of the amino acids differs pressure seems to have a greater effect on the reaction pathway than temperature. As had been recognized earlier, the effect of pressure would have slowed down certain decomposition reactions, such as pyrolysis and decarboxylation (Blank et al., 2001). 

Slow pyrolysis, also called carbonization, is characterized by a high charcoal yield and is not considered for hydrogen production processes. The slow pyrolysis of wood (24 h typical residence time) was a common industrial technology to produce charcoal, acetic acid, methanol, and ethanol from wood until the early 1900s. 

Pyrolysis is a type of gasification that breaks down the biomass in oxygen deficient environments, at temperatures of up to 400°F. This process is used to produce charcoal. Since the temperature is lower than other gasification methods, the end products are different. The slow heating produces almost equal proportions of gas, liquid and charcoal, but the output mix can be adjusted by changing the input, the temperature, and the time in the reactor. The main gases produced are hydrogen and carbon... 

Scheme 48). The very slow pyrolysis of the (4-methylphenyl)amine derivative (1223, R = Me) at 540°C and 10 5 torr resulted in IR absorption at 2079 cm-1, indicating the presence of methyleneketene (1224, R = Me). Under less carefully controlled pyrolysis conditions at higher pressure, the 2079 cm-1 absorption was accompanied by an absorption at 2123 cm 1, pointing to the presence of imidoylketene (1225, R = Me). Above 600°C, both intermediates disappeared and quinoline (1226, R = Me) was the only product. 

The correction for the pyrolytic production of elemental carbon is accomplished by measuring the amount of elemental carbon oxidation necessary to return the filter reflectance to its initial value. This is facilitated by the three-step elemental carbon oxidation which produces a relatively slow initial rise in the reflectance. A typical output is shown in Figure 3. The pyrolysis correction corresponds to the shaded area which is added to peaks 1 and 2 to give the corrected value for organic carbon. This procedure assumes that the mass absorption coefficient of the pyrolytically produced elemental carbon is the same as that of the original elemental carbon. Research to test this assumption is continuing. 

Perhaps one of the best known syntheses of a heterocyclic polymer via the modification method is the generation of nitrogen-containing ladder polymers by pyrolysis of polyacrylonitrile) (77MI11109). The thermolysis is known to take place in discrete steps. The first step in the sequence, which can take place with explosive violence if the heating rate is not sufficiently slow, occurs at about 150 °C and can be detected by the onset of intense color formation. The product of this reaction (Scheme 101) is the cyclic tetrahydropyridine ladder structure (209). The next step, which is conducted in the presence of air at ca. 250 °C, involves the thermooxidation of polymer (209) to form what is best described as terpolymer (210) containing dihydropyridine, pyridone and pyridine units. 

Poly(a-phenylethyl isocyanide), however, yields complex products distinguishable from monomer upon thermal degradation at 20 mm Hg (13). At 300° C a viscous condensate is produced which is free of isocyanide absorption in its infrared spectrum and appears very similar to the recently synthesized oligo-isocyanides, a,co-dihydrotri(a-phenylethyl isocyanide) and a,co-dihydrohexa(a-phenylethyl isocyanide) (15). Pyrolysis at 500° C produces an intense broad infrared absorption band in the range about 3300 cm-1, which is the range of associated N il bonds. Pyrolysates obtained at 700° C reveal nitrile absorption at 2270 cm"1, that becomes more intense in pyrolysates produced at temperatures up to 1300° C. A slow pyrolysis at 200-300° C is indicated for the study of primary structural changes in poly(a-phenylethyl isocyanide). Pyrolysates of poly(<7-... 

Pyrolysis of Sodium-Tetramethylammonium Zeolite Omega. Preliminary calcinations of the Q zeolites showed that intracrystalline diffusion restrictions interfered greatly with transport both of oxygen and of calcination products. Under mild conditions, coking was observed, and even under favorable conditions (550° C, thin beds, good venting) the reaction was slow. Some samples of zeolite were pyrolyzed under vacuum, and the products were identified by low resolution mass spectrometry. 

---