Hydrogenation hydrogen supply

Depending on its rank, coal can be dissolved in as little as one minute in the temperature range of 623 to 723 K (662 to S42°F) in suitable solvents, which are assumed to promote thermal cracking of the coal into smaller, more readily dissolved fragments. These fragments may be stabilized through reactions with one another or with hydrogen supplied either by a donor solvent or from a gas phase. 

Thomas, C. E. Kuhn, I. F. James, B. D. Lomax, F. D. and Baum, G. N. (1998). Affordable Hydrogen Supply Pathways for Fuel Cell Vehicles. InternnaomilJournal of Ilydrogcn Energy 23(6). 

In many instances, more than one type of reaction can take place at any given temperature. When the reduction reaction plays an important part, it is usually possible to alter the composition and characteristics of the coating by controlling the hydrogen supply to the reaction chamber. 

Palladium Diffusion. Palladium is very permeable to hydrogen but not permeable to other gases. As a result, it is a useful hydrogen purifier. A palladium membrane, heated to 400 °C, purifies hydrogen to <10 ppb but requires a high pressure differential for net diffusion to take place at reasonable rates of hydrogen supply. 

Catalytic hydrogen supply from a decalin-based chemical hydride under superheated liquid-film conditions... 

EfiBdent hydrogen supply iiom decalin was only accomplished by the si terheated liquid-film-type catalysis under reactive distillation conditions at modaate heating tempaatures of 210-240°C. Caibcm-supported nano-size platinum-based catalysts in the si ietheated liquid-film states accelerated product desorption fixjm file catalyst surface due to its temperature gradient under boiling conditions, so that both hi reaction rates and conversions were obtained simultaneously. 

Figure 8.32. PEMFC potential as a function of current density for different CO contents in the hydrogen supply. Note the rapid drop in potential as soon as current is drawn, even for pure hydrogen. This is due to overpotentials in the system, while the monotonic decrease at higher current is attributed to the internal resistance of the PEM. [Adapted from H.F. Oetjen,...

The reaction rates cannot be set as high as intrinsically possible by the kinetics, because otherwise heat removal due to the large reaction enthalpies (500-550 kj mol ) will become a major problem [17, 60, 61]. For this reason, the hydrogen supply is restricted, thereby controlling the reaction rate. Otherwise, decomposition of nitrobenzene or of partially hydrogenated intermediates can occur ]60], The reaction involves various elemental reactions with different intermediates which can react with each other ]60], At short reaction times, the intermediates can be identified, while complete conversion is achieved at long reaction times. The product aniline itself can react further to give side products such as cyclohexanol, cyclohexylamine and other species. 

Figure 5.28 Schematic of the experimental set-up. Water/ethylene glycol/SDS reservoir (a) high-pressure liquid pumps (b) catalyst/ substrate HPLC injection valve with 200 pi sample loop (c) hydrogen supply, equipped with mass flow controller (d) micro mixer (e) heating jacket (f) tubular glass or quartz reactor (g) back-pressure regulator (h) [64],...

For a production rate of 10,000 tonnes per year of hydrogen chloride, calculate the heat removed by the burner jacket and the heat removed in the external cooler. Take the excess hydrogen as 1 per cent over stoichiometric. The hydrogen supply contains 5 per cent inerts (take as nitrogen) and is fed to the burner at 25°C. The chlorine is essentially pure and is fed to the burner as a saturated vapour. The burner operates at 1.5 bar. 

A two-stage centrifugal compressor will be used for both duties. Take the polytropic efficiency for both compressors as 70 per cent. The hydrogen supply pressure is 120 kN/m2 and the temperature 25 °C. The hydrogen chloride is cooled to 50 °C after leaving the burner. Assume that the compressor intercooler cools the gas to 50 °C, for both duties. 

The catalyst powders were compressed to thin disks under a pressure of about 50 kg/cm2, with the exception of the alumina-supported catalysts which required a pressure of 1500 kg/cm2 to obtain reasonable transmittance. The samples were reduced in a stream of hydrogen supplied at a rate of 10 1 hr-1 (SV 30,000 hr-1). The temperatures of reduction were 350°-450°C for the nickel samples, 475°C for the palladium samples, and 425°C for the iridium catalysts. 

Superheated Liquid-Film-Type Catalysis for Hydrogen Supply.441... 

Demonstration Test for Efficient Hydrogen Supply from... 

Onboard Hydrogen Supply from Organic Chemical Hydrides.462... 

Dehydrogenation activities, compared for tetralin and decalin [5,12] under the same superheated liquid-film conditions over the same Pt/C catalyst, exhibited around 3.9-63 times preference of tetralin (Table 13.3), which can certainly be ascribed to advantageous adsorption due to the a-bonding capability of its aromatic part [17-19]. It was, thus, confirmed experimentally that tetralin is superior to decalin as the organic hydrogen carrier for stationary applications in terms of rapid hydrogen supply or power density, provided that the density of fuel storage is unimportant. 

Demonstration Test for Efficient Hydrogen Supply from Decalin with Superheated Liquid-Film-Type Catalysis by Use of Bench-Scale Continuous Reactor... 

In the case of 50 kW power, the rate of hydrogen supply needed (LH) is around 1.69 X 103 (mol/h) at the energy-conversion-efficiency level of 45% for the proton exchange membrane fuel cell (PEM-FC) [38]. 

The onboard hydrogen supplied from organic chemical hydrides will be utilized well in the ICE vehicles. Even for stationary use of hydrogen, distribution of organic chemical hydrides will play an important role at stations or sites, where waste heat at modest temperatures is dissipated in vain without chemical recuperation. 

---