33 research outputs found
Methane pyrolysis on sponge iron powder for sustainable hydrogen production
Methane pyrolysis is one of the possible methods to produce low-carbon hydrogen. One of the most promising catalysts for methane pyrolysis is Fe due to its availability, relatively low cost and high working temperature. In the presented paper, the methane pyrolysis on unsupported (without a carrier) sponge iron in the form of powder was studied in the temperature range of 700â1100 ⊠C. Methane pyrolysis was carried out in a stainless-steel tube reactor with an inner diameter of 10 mm. The reactor was heated locally by propane burner, the length of the heated zone was about 8 cm along the reactor tube. Methane feed rates were about 50, 100, and 200 ml/min, and the residence time of methane in the 8 cm long reaction zone was about 4, 2 and 1 s, respectively. The hydrogen yield increased with an increase in the temperature and a decrease in methane feed rate. At 700â800 âŠC, the hydrogen yield did not exceed 20%. At 900 âŠC, the yield reached 28.6% at a residence time of about 4 s. At 1000 âŠC, hydrogen yield was about 40 and 66.5% at a residence time of about 1 and 4 s, respectively. At 1100 âŠC, hydrogen yield varied in the range of 70â85%. The use of a catalyst increased the hydrogen yield by 81% compared to the experiment without a catalyst at 1100 âŠC. The catalytic effect of sponge iron powder can be used in the development of methane pyrolysis plants
Conservative dynamic systems
Systems, assuming the first integral, are considered in the paper aiming at the creation of the detailed theory of small oscillations. During the investigation methods of the Puankare -Diulack normal form theory have been used. As a result the normal form theory has been created. Stability criteria have been obtained. The behaviour of periodical trajectories has been investigatedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio
Porous Structure of Acetylene Black after Heat Treatment
Abstract The porous structure of acetylene black samples obtained by decomposition of acetylene at various pressures in a constant-volume tube reactor and subsequent heat treatment in an inert medium at temperatures of 200, 400, 600, 800, 1000, 1200, and 1400°C has been studied. Nitrogen adsorption isotherms at 77 K were obtained by the low-temperature adsorption method, and the textural characteristics of carbon black were calculated from them. It was found that at a pressure increased from 2.5 to 5 bar during the decomposition of pure acetylene, the surface area of acetylene black did not change and amounted to 88 and 83 m2/g (according to BET), respectively. As a result of heat treatment in the inert medium, the specific surface area obtained at 2.5 bar decreased relative to that of the starting carbon black not subjected to heat treatment. The average pore radius determined by the BarrettâJoynerâHalenda (BJH) method did not change at different temperatures and pressures and amounted to 1.62 nm. A scanning electron microscopy study shows that the average particle size decreased from 53 to 40 nm at increased initial pressure of acetylene. Based on the results, it can be concluded that subsequent heat treatment does not lead to an appreciable change in the particle shape and size, nor in the overall structure of the carbon black surface. A thermogravimetric analysis (TGA) of the original carbon black sample in an inert medium was performed. It shows that the mass of carbon black increased by 4% when the sample was heated to 400°C, did not change on heating from 400 to 1150°C, and decreased by 1% on heating from 1150 to 1400°C
Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures
On the basis of granular synthetic zeolites NaY, HY, and ZSM-5, adsorbents containing nanoparticles of silver, cobalt, molybdenum, and tungsten were obtained. The samples have a lower surface polarity in comparison with the initial zeolites, which is reflected in the selectivity of a number of samples with respect to argon. This is due to the fact that the argon molecule interacts with zeolites only through nonspecific forces. Modification was performed by interacting with reverse-micellar solutions of nanoparticles. The actual sizes of metal particles and their distribution over the surface of the modified samples of zeolites have been determined by the method of transmission electron microscopy. The samplesâ equilibrium adsorption capacities for oxygen and argon (25°Х and atmospheric pressure) and the separation coefficient of the argonâoxygen mixture as the ratio of Henryâs coefficients have been determined. It has been demonstrated that samples of the NaY zeolite modified with silver nanoparticles have the separation coefficient value of the argonâoxygen gas mixture equal to 1.6
Aluminium Alloys Smelting in Shaft- Reverberatory Furnaces in a Liquid Bath Mode
The aim of research was creation of a furnace for aluminum alloys smelting âin a liquid bathâ in order to reduce metal loss. In the paper, the author demonstrates the results of research on smelting of aluminum alloys in a shaft-reverberatory furnace designed by the author. It has been shown that smelting aluminum alloy in a liquid bath was able to significantly reduce aluminum loss and that shaft-reverberatory design provided high efficiency and productivity along with lower energy costs. Ensuring continuous operation of the liquid bath and superheating chamber, which tapped alloy with the required texture, was achieved by means of the optimal design of partition between them. The optimum section of the connecting channels between the liquid bath of smelting and the superheating chamber has been theoretically substantiated and experimentally confirmed. The author proposed a workable shaft-reverberatory furnace for aluminum alloys smelting, providing solid charge melting in a liquid bath