Hydropyrolysis processes, production

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. 

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. 

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 ... 

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. 

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. 

Mechanism of Hydropyrolysis of -Paraffins. The hydrogen carbon ratio in the total hydropyrolysis product from 1 is higher (H C > 2.2) than that in 1 itself (H C = 2.12) in all experiments performed (Tables II and III). This clearly indicates participation of hydrogen in the process. To account for the observed differences between hydropyrolysis and conventional thermal cracking (Table I), and to rationalize the variations in product composition as a function of reaction conditions,... 

The differences in liquid product composition from the two types of processes are even more pronounced. The major liquid products (see Table V) from hydropyrolysis of 2 at 550°C are C6-Ci0 cyclohexenes and cyclohexanes, and C5-C8 open-chain hydrocarbons, while in thermal cracking the main liquid product at this temperature is 1,2,3,4,5,6,7,8-octahydronaphthalene. At 600°C a much higher conversion of 2 into C5—C10 aliphatic products is observed in the hydropyrolysis Experiment 25, whereas in the thermal cracking Experiment 26 there is much higher formation of aromatic products, i.e., benzene, toluene, ethylbenzene, and... 

Iron ore catalysts, modified by mechanical treatment were found to show a catalytic activity in the process of hydropyrolysis of biomas / plastic mixtures. Some synergistic effects were observed in this process resulting in the increase of conversion degree and yield of light liquid fraction and in the decrease of hydrocarbons content in gaseous products. 

The three feedstocks were processed by hydropyrolysis at selected process conditions. Previous results (1,7) have shown that gas to liquid ratios increase sensitively with increasing temperature. This effect can be offset somewhat by decreasing the residence time. A variation in pressure does not have a major effect on product yields or gross properties, but pressures above about 1200 psig are required to inhibit coke formation. 

TS-IIC represents the material retained in a hot (350-400°C) catch tank and is believed to be indicative of the amount of material which is not volatilized during reaction. Extensive experimentation with hydropyrolysis has shown that actual coke production of much less than 1% is achieved. Details of minor coke buildup over extended runs have not yet been determined. The optimum conditions to obtain the desired yields and to prevent extraordinary coke formation will depend upon the feedstock properties and composition. Quantitative relationships between feedstock composition and optimum process conditions have not yet been conducted. 

Overall, process conditions for hydropyrolysis are no more severe than practiced now in catalytic hydrogenation processes. Considering the significantly increased yields of valuable liquid and gaseous products (compared to coking) and the rather simple process configuration, the economics of hydropyrolysis look promising. 

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