Hydropyrolysis process

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. 

Hydropyrolysis process gives the higher degree of mixture conversion and higher yield of light liquids as compare to pyrolysis in an inert atmosphere. Observed in some cases non-additive effects indicate that the interaction between wood and plastic derived products takes place during mixture thermal treatment. The more pronounced synergistic effects were detected for hydropyrolysis process. Iron catalysts promote the formation of liquid hydrocarbons from biomass/plastic mixtures and influence on their coit sition. 

Utilization of wood-biomass residues as well as waste polymers is the important direction of recent research activities. It is known that direct catalytic liquefaction of plant biomass can be used to produce liquid fuels and chemicals [1,2]. Co-pyrolysis and co-hydropyrolysis processes have the potential for the environmentally friendly transformation of lignocellulosic and plastic waste to valuable chemicals. 

The influence of the process temperature on catalytic hydropyrolysis of biomass/plastic mixture was studied in the range 360 - 460 C. Fig. 3 shows that the highest conversion (91% wt.) of the pine wood / polyethylene mixture (1 1 weight ratio) was observed at 390 C - 430 C in the presence of activated haematite catalyst. Higher tenqieratures promote increased yields of char and gaseous products. At lower temperatures a reduced yield of distillate fraction was observed. In comparison with pyrolysis in inert atmosphere the increased yields of light hydrocarbon fractions (by 1.6 - 1.8 times) and increased degree of mixture conversion (by 1,2 time) were observed for hydropyrolysis process. 

The hydropyiolysis of pine wood at 390°C in the presence of activated haematite catalyst gives e wood conversion degree 54 wt.%. Under the same hydropyrolysis process conditions about 99.5% wt. of polyediylene was converted to liquid and gaseous products. 

Hydropyrolysis Process. Two hydropyrolysis reactors were used in this study. The Sunnyside and Asphalt Ridge bitumen were processed in a reactor consisting of a coiled stainless steel tube 3/16" i.d. x 236" long. This reactor has been previously described by Ramakrishnan (1). The TS-IIC oil was processed in a reactor originally developed for short residence time coal liquefaction. This reactor also consists of coiled stainless steel tubes 3/16" i.d. The length of this tube system can be varied from 20 to 120 feet, and has been previously described by Wood, et al. (10). The length of the reactor for runs reported in this paper was 100 feet. Average residence times were calculated from the volumetric flow rates and the reactor volume at process conditions. The reaction mixture, which is predominantly H, was assumed for purposes of this calculation to behave as an ideal gas. The reactors were pre-sulfided with H S to inhibit catalytic reactions from wall surfaces. 

Hydropyrolysis processing is probably best suited for those feedstocks which can best utilize the inhibition effects of hydrogen on polymerization, condensation, and aromatization reactions. Such feedstocks are high molecular weight naphthenic materials which are susceptible to cracking but are easily converted to coke by liquid-phase bimolecular reactions. 

The pyrolysis and hydropyrolysis process produces liquid product and char Either fluidized beds or entrained beds are used for this process The reaction kinetics and reactor modelling of solid-gas systems have already been discussed earlier ... 

I) Pyrolysis and Hydropyrolysis Processes (Lurgi-Ruhrgas COEd/ Occidental etc.)... 

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... 

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. 

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. 

What, then, does the future hold This author believes that the catalytic hydrocarbonization/gasification concept will ultimately achieve commercial success for the production of liquid and gaseous fuels from coal. In selected applications, the mild hydrocarbonization of western coal to produce liquid and gaseous fuels with power generation from the low-sulfur char may also be commercially attractive. Finally, further development of the flash hydropyrolysis technology, as exemplified by the Rocketdyne project, may eventually lead to a technically and economically attractive liquefaction process. But the most important questions still remain unanswered. Does private industry have sufficient interest to pursue the possibilities Where is the interest focused Will a private consortium build a hydrocarbonization/ cogeneration complex using western coal Will the phoenix arise from the ashes ... 

To test these hypotheses, a tar sand bitumen containing 20 wt % pentane asphaltenes was characterized and processed by hydropyrolysis before and after removal of asphaltenes. Product yields and structure were determined and the influence of asphaltenes on results was determined by inferrence. Feedstocks and products were characterized according to elemental analysis, physical properties, simulated distillation, and carbon-type analysis. Inferences made in this study are discussed in the context of the reported literature. 

The asphaltene contents of the products were measured and reveal that some 11% asphaltenes are contained in the products from maltene processing (Table IV). The presence of pentane insolubles in this product is remarkable as they are either produced by hydropyrolysis or they are fragments of previously soluble molecules in the maltenes. Later discussion will show that hydropyrolysis successfully inhibits the generation of substantial quantities of aromatic carbon thus we might reasonably assume the latter explanation dominates. 

---