Thermal conversion hydrogenation

Thermal conversion of organic waste material, such as plastics, or of biomass under the influence of oxygen into crude synthesis gas yields a hydrogen gas. 

Hydrogen can be obtained by direct electrolysis, by direct thermal conversion, ther-mochemically, photochemically, photoelectrochemically, and biochemically from water. 

Furans can be converted into N- alkylpyrroles by heating with primary amines and alumina. Similar thermal conversions of furans and benzo[6]furans to their sulfur analogues in the presence of alumina or other metal oxide catalysts and hydrogen sulfide are also known. l,3-Diphenylbenzo[c]furan is converted into the thiophene by heating with phosphorus pentasulfide. The mechanism of these reactions is obscure. 

There are several possible flow scheme variations involved for this process. It can operate as an independent unit or be used in conjunction with a thermal conversion unit (Figure 9-25). In this configuration, hydrogen and a vacuum residuum are introduced separately to the heater, and mixed at the entrance to the reactor. T o avoid thermal reactions and premature coking of the catalyst, temperatures are carefully controlled and conversion is limited to approximately 70% of the total projected conversion. The removal of sulfur, heptane-insoluble materials, and metals is accomplished in the reactor. The effluent from the reactor is directed to the hot separator. The overhead vapor phase is cooled, condensed, and the hydrogen separated from there is recycled to the reactor. 

Thermal power generated by the reactor is converted to chemical power in a thermal conversion unit where, in the MHR-T option with methane reforming, thermochemical reaction is initiated converting initial steam-gas mixture to hydrogen-enriched converted gas (mixture of water steam, CO, H2, C02, and CH4). 

Technical solutions relating to selection of the thermal conversion unit design mainly depend on the results of analysis of various accident modes of the selected design, and estimates of diffusion flows (hydrogen flow to primary circuit and tritium flow to process circuit), i.e. on those problems which are connected with validation of possible failure as a result of intermediate circuit application. 

One reason for the interest in fuel cells is that they offer a far more efficient way of utilizing chemical energy than does conventional thermal conversion. The work obtainable in the limit of reversible operation of a fuel cell is 229 kJ per mole of H20 formed. If the hydrogen were simply burned in oxygen, the heat obtainable would be -AH° = 242 kJ mol-1, but no more than about half of this heat can be converted into work so the output would not exceed 121 kJ mol-1. 

G-3 Estimated costs for conversion of natural gas to hydrogen in plants of three sizes, current and possible future cases, with and without sequestration of C02, 202 G-4 Estimated effects of the price of natural gas on the cost of hydrogen at plants of three sizes using steam methane reforming, 204 G-5 Power cycle net efficiency (qel) and thermal-to-hydrogen efficiency (qH) for the gas turbine modular helium reactor (He) high-temperature electrolysis of steam (HIES) and the supercritical C02 (S-C02) advanced gas-cooled reactor HTES technologies, 212... 

Scott and Agopian have described the thermal conversion of triquinacene to azulene at 600 °C in a quartz flow system.402) The process requires the loss of two hydrogen atoms, possibly as molecular hydrogen. The dehydrotriquinacene 453 could be a key reactive intermediate. 

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