Methane from pyrolysis

Figure 2 Methyl coverage in monolayers (ML) as a function of methyl exposure, in langmuirs (L) of mixture of gases from pyrolysis source. Symbols are data showing the sum of methane formed plus residual carbon. Consistent values are obtained by summing hydrogen appearing in CH4 and H2 gas-phase products. Solid line is a guide to the eye.

When the pyrolysis temperature increased the biochar yield decreased. The biochar yield increased with increasing particle size of the sample. The yield of biooil from pyrolysis of the samples increased with temperature. Anaerobic biogas prodnction is an effective process for conversion of a broad variety of agricultural biomass to methane to snbstitnte natnral gas and medinm calorific valne gases. 

In this configuration, the hydrogen and the methane from the demethanizer column are spUt into their component streams. The hydrogen is for use in various downstream processes and the methane is used as a fuel-gas stream. Bottoms from the de-ethaniser are further split into C3 and C4. stream. The C3 is treated similarly to the C2 to produce polymer grade propylene. After removing the C4 fraction, which is passed to downstream separation units, the heavy components form pyrolysis-gasoUne. The latter may be further separated to produce benzene, toluene and xylene. 

Trifluoronitrosomethane may be obtained from photolysis of a mixture of trifluoroiodo-methane and nitric oxide [275, 276] or from pyrolysis of trifluoroacetyl nitrite [277, 278] (Figure 8.108). 

Figure 7. Effects of pressure and coal particle size on yields of total volatiles, tar plus hydrocarbon liquids, all hydrocarbon gases, and methane, from bituminous coal pyrolysis. Heating rate = 1000°C/sec. Temperature = 1000°C. Isothermal holding time = 2-10 sec. Particle diameters, ixm C) 74 (X) 297-833 (O) 833-991 (14).

Waterloo s hydrogasification work has been technically highly successful, resulting in 75% conversion of carbon from wood to methane via pyrolysis over a nickel-alumina catalyst with hydrogen at about 550 C and 440 ms residence time. 

The start temperature of the pyrolysis reaction may in all cases be clearly ascertained. The onset temperatures of the experiments in 1 bar argon fall between 390-422 °C and for the experiments in 10 bar methane, from 392-420 °C. Statistical evaluation gives small coefficients of variation (Table 4-41). 

Poly(ethylene terephthalate) decomposes upon heating through a series of different reactions. These run either concurrently or consecutively. The result is a complex mixture of volatile and nonvolatile products. It was found that when poly(ethylene terephthalate) is maintained in molten condition under an inert atmosphere at 282-323°C, it slowly converts to a mixture of gaseous low molecular weight fragments [581]. The major products from pyrolysis of poly(ethylene terephthalate) are carbon dioxide, acetaldehyde and terephthalic acid. In addition, there can be detected trace amounts of anhydrides, benzoic acid, p-acetylbenzoic acid, acetophenone, vinyl benzoate, water, methane, ethylene, acetylene, and some ketones [505]. The following mechanism of degradation was postulated [505] ... 

In the USA, and to some extent in Great Britain and Norway, ethane is the dominant feedstock for steam cracking. It is recovered from wet natural gas and gives high yields of ethylene, hydrogen and methane. From naphtha, the preferred feedstock in Europe and Japan, additional principal products are propylene, C4 hydrocarbons and pyrolysis naphtha as well as highly aromatic pyrolysis tar. 

The corresponding six-membered heteroqrcle, pyridine (azabenzene) was initially obtained by the dry distillation of bones, and much of it is obtained from pyrolysis of coal or oil shale. There is a commercial synthesis that utilizes the vapor-phase reaction between formaldehyde (methanal, H2C=0), acetaldehyde (ethanal. 

Gaseous products from pyrolysis of [Zr(acac)2(C HgO)2] are more complicated (Figure 2b). Methane, carbon dioxide and water vapor were detected by both of GC and MS analysis. Water vapor releases covering broad temperatures from 150 C to above 1000°C. Maximum methane releases at about 500°C as compared to carbon... 

Biomedical. Heart-valve parts are fabricated from pyrolytic carbon, which is compatible with living tissue. Such parts are produced by high temperature pyrolysis of gases such as methane. Other potential biomedical apphcations are dental implants and other prostheses where a seal between the implant and the living biological surface is essential. Plasma and arc-wire sprayed coatings are used on prosthetic devices, eg, hip implants, to achieve better bone/tissue attachments (see Prosthetic and BiOLffiDiCALdevices). 

Of the many forms of carbon and graphite produced commercially, only pyrolytic graphite (8,9) is produced from the gas phase via the pyrolysis of hydrocarbons. The process for making pyrolytic graphite is referred to as the chemical vapor deposition (CVD) process. Deposition occurs on some suitable substrate, usually graphite, that is heated at high temperatures, usually in excess of 1000°C, in the presence of a hydrocarbon, eg, methane, propane, acetjiene, or benzene. 

Although ethylene is produced by various methods as follows, only a few are commercially proven thermal cracking of hydrocarbons, catalytic pyrolysis, membrane dehydrogenation of ethane, oxydehydrogenation of ethane, oxidative coupling of methane, methanol to ethylene, dehydration of ethanol, ethylene from coal, disproportionation of propylene, and ethylene as a by-product. 

Complete removal of water from the pyrolysis gas is achieved with molecular sieve dryers. Typically, there are two dryers one is in normal operation while the other is being regenerated. The dryers are designed for 24 to 48 hours between successive regenerations and high pressure methane heated with steam at 225°C is the preferred regeneration medium. Activated alumina was used in older plants, but it is less selective than molecular sieves (qv). 

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