Hydropyrolysis

Hydropyrolysis occupies a position midway between coal pyrolysis and coal liquefaction. This process, which is currently being developed to complement coal liquefaction, operates at pressures up to 100 bar and temperatures up to 900 °C the residence time of the coal in the pyrolysis zone is around 4 to 5 sec. 

Hydropyrolysis is characterized by the fact that the yield of coke, which can reach 80% in purely pyrolytic processes, is significantly reduced and more gaseous hydrocarbons and around 20% of tar are produced. The aromaticity of the tar generated by hydropyrolysis at 530 °C is 0.80, rising to 0.95 at a reaction temperature of 950 °C. 

The hydropyrolysis of coal is related to the hydropyrolysis of naphtha the latter was operated in a pilot plant belonging to Naphtha Chimie/Pierrefitte-Auby to produce ethylene, in 1975. 

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Process development of the use of hydrogen as a radical quenching agent for the primary pyrolysis was conducted (37). This process was carried out in a fluidized-bed reactor at pressures from 3.7 to 6.9 MPa (540—1000 psi), and a temperature of 566°C. The pyrolysis reactor was designed to minimize vapor residence time in order to prevent cracking of coal volatiles, thus maximizing yield of tars. Average residence times for gas and soHds were quoted as 25 seconds and 5—10 rninutes. A typical yield stmcture for hydropyrolysis of a subbiturninous coal at 6.9 MPa (1000 psi) total pressure was char 38.4, oil... 

The Effect of Catalyst Concentration, Temperature, and Residence Time on the Chemical Structure of Coal Hydropyrolysis Oils... 

In this paper we have looked firstly at the effect that the catalyst concentration, secondly at the effect that the reactor temperature and finally at the effect that the residence time at temperature have on the chemical structure of the oils (hexane soluble product) produced on hydropyrolysis (dry hydrogenation) of a high volatile bituminous coal. Generally, the hydropyrolysis conditions used in this study resulted in oil yields that were considerably higher than the asphaltene yields and this study has been limited to the effects that the three reaction conditions have on the chemical nature of the oils produced. 

Thus, the question is whether such classes of molecules were present on the young Earth. The only witnesses capable of giving an answer to this question are meteorites (Deamer, 1988). The group of David Deamer studied Murchison material after extraction and hydropyrolysis (at 370-570 K, with reaction times of several hours or days). GC and MS analyses showed the presence of a series of organic compounds, including significant amounts of amphiphilic molecules such as octanoic (C ) and nonanoic acids (C9) as well as polar aromatic hydrocarbons. 

Hydropyrolysis A catalytic process for converting coal into a mixture of liquid and gaseous products. It is operated at high temperatures and pressures, with a residence time in the pyrolysis zone of only a few seconds. 

Hydroprocessing, in petroleum refining, 18 654-657 Hydropulping, 10 535 Hydropyrolysis, coal liquefaction, 6 854 Hydroquinolines, 21 198-199 Hydroquinone (HQ) from benzene, 3 620 as a black-and-white chemical reducing agent, 19 205-206 in bleaching preparations, 7 847 clathrates, 14 160 dye releaser, 19 291-292 inclusion compounds in, 14 172, 174 intermediate used in oxidation hair dyes, 7 858t... 

Flash-liquid Liquid obtained from flash pyrolysis accomplished in a time of < 1 s Flash-gas Gaseous material obtained from flash pyrolysis within a time of < 1 s Hydropyrolysis Pyrolysis with water Methanopyrolysis Pyrolysis with methanol Ultrapyrolysis Pyrolysis with very high degradation rate... 

Pyrolysis processes simply cook the feedstock in an essentially inert atmosphere at relatively low temperatures (500°to 700°C) hydropyrolysis operates under similar conditions, but in a reducing atmosphere. 

Hydrogen addition processes, catalytic hydroconversion (hydrocracking), fixed bed catalytic hydroconversion, ebullated catalytic bed hydroconversion, thermal slurry hydroconversion (hydrocracking), hydrovisbreaking, hydropyrolysis, and donor solvent processes. 

Hydropyrolysis a short residence time high temperature process using hydrogen. 

For a so-called "advanced process of flash hydropyrolysis, (14), a paper by Rockwell International and Cities Service Research and Development reported a 1977 minimum high Btu gas price of 2.36/MMBtu from western subbituminous coal using "AGA/ERDA cost guidelines" with utility financing under conditions yielding significant quantities of by-product BTX liquids. For details, reference was made to contractual reports. 

Finally, a number of options exist for the production of high-Btu gas by hydrocarbonization and hydropyrolysis processes. 

The available information leads one to believe that the maximum production of liquids with no net hydrogen consumption and the low-temperature catalytic hydrocarbonization/gasification are alternatives which appear to have great merit. The former of these, when applied to western coals, appears to be technically ready for commercial application and economically competitive with alternative coal liquefaction processes. Advantages of the flash hydropyrolysis processes over the Coalcon process are difficult to perceive. 

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