Deoxygenation is in high demand in the titanium industry. This research was carried out to experimentally determine the oxygen removal limits by the novel hydrogen-assisted Mg deoxygenation method. Spherical Ti and Ti-6Al-4V (or TC4, Ti64) powders with around 2.2 wt% oxygen were prepared for the deoxygenation research. The deoxygenation kinetics were modeled based on a non-steady-state radial diffusion. The results show that in the β phase region, the time to reach the equilibrium is slightly affected by the initial oxygen content in titanium, but is strongly influenced by the particle size. The reliance of the equilibrium duration on the diffusion coefficient is stronger when the particle size is larger. Guided by the kinetic prediction, deoxygenation experiments were carried out. Under a 1 atm pure H 2 atmosphere, the deoxygenation limits by Mg for pure Ti are 252 ppm at 700 °C, 289 ppm at 750 °C, and 554 ppm at 800 °C, and for TC4 are 296 ppm at 750 °C, 371 ppm at 800 °C, and 743 ppm at 850 °C, consistent with the thermodynamics that a lower temperature possesses a more potent driving force for deoxygenation. These data have clearly demonstrated the strong deoxygenation capability of the hydrogen-assisted Mg deoxygenation method.
Tangxin Zhang,Hao Zhang,Tiantian Zhu,Yuhua Mao,Jiayuan Wang,Lingyu Zhu,Jianli Wang
In de-oxygen water preparation, it is still a challenge to develop a highly efficient catalyst with less pollution on produced water. Herein, we invented a novel catalytic membrane, in which palladium nanoparticles were well dispersed and exposed sufficiently to the fluid with the help of hydrophilic polymer networks. These catalytic membranes created by dynamic filtration and reversible fixation offer exceptional flexibility in preparation and application. An apparatus for flexible and continuous chemical removal of dissolved oxygen from water was built up and applied to determine the performance of catalytic membranes. When the residence time was 32.3 s, the concentration of DO could be reduced to 10 ppb by a tri-layer catalytic membrane at ambient temperature. This uniquely configured catalytic membrane could be applied in portable and flexible DO requirements, such as experimental setups and pretreatment of instruments.
Lei Chen,Zhi-Cong Wang,Dabo Chen,Lin-Xin Yin,Pei-Gao Duan
We report a new process to realize the deep removal of N, O, and S from the bio-oil when using a batch reactor to do the hydro-upgrading experiments. That is, within a fixed reaction time, hydro-upgrading of the bio-oil was carried out in several stages. After each stage reaction was finished, the reactor was cooled, and the gas in the reactor was replaced with fresh hydrogen, and then the reaction continued until the total reaction time was complete. A bio-oil produced from hydrothermal liquefaction of microalgae mixed with tetralin at a mass ratio of 1:1 was used as the feedstock . The experiments were performed at different temperatures (300–480 °C) and time (1–8 h) with fixed addition of 10 wt% Pt/C and 8 MPa H 2 . Higher treated bio-oil yield was always achieved if the reaction was performed in several stages. The N-, O-, and S- containing compounds in the gaseous products mainly consisted of C 2 H 4 N, C 3 H 7 N, C 6 H 7 N, NH 3 , (SCN) 2 , SO 2 , and H 2 O. The removal of these gas products avoided their secondary reactions with the bio-oil and slowed down the catalyst poisoning , and thus breaking through the equilibrium limitations of denitrogenation, desulfurization , and deoxygenation and prolonging the activity of the catalyst.
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