Yan Zhao,Haoyu Fang,Liguo Zhu,Lingxin Kong,Bin Yang,Baoqiang Xu,Lei Gao
As the mainstream method for titanium processing, the Kroll process has excessive carbon emissions and high energy consumption due to its reliance on fossil fuels and lengthy semi-continuous process, which not only hinders the implementation of “dual-carbon” goals, but also leads to high production costs. In contrast, molten salt electrolysis achieves direct electrochemical reduction, significantly reducing energy consumption and pollution emissions while reducing costs, in line with the needs of green and sustainable manufacturing. The USTB method represented by soluble anode electrolysis process, is a green and low-cost new process for titanium extraction. However, this method uses NaCl-KCl as the molten salt medium, and faces the problem that it is difficult to control the oxygen content of titanium. In this study, a new method for the preparation of low-oxygen titanium by synergistic electrolysis and thermal deoxidation in NaCl-KCl-YCl 3 was proposed. It can be seen from the thermodynamic calculations that the activity of O 2− in the molten salt can be effectively reduced by the formation of YOCl. Under the equilibrium of Y / YOCl / YCl 3 (Y 3+ (in flux) + O 2- (in flux) + Cl − (in flux) = YOCl), the deoxidation limit is 1000 ppm. The experimental results show that the metal titanium with oxygen content of 700 ppm can be prepared by molten salt electrolysis and thermal deoxidation with TiC x O y as anode, Mo as cathode in NaCl-KCl-YCl 3 molten salt. This work provides a novel strategy for the preparation of low-oxygen titanium based on soluble anode electrolysis.
Shi Haonan,Gu Xiaoyu,Shi Yinteng,Wang Dandan,Shu Sihao,Wang Zhongze,Chen Jixiang
Porous carbon-encapsulated Ni and Ni–Sn intermetallic compound catalysts were prepared by the one-pot extended Stöber method followed by carbonization and tested for in-situ hydrothermal deoxygenation of methyl palmitate with methanol as the hydrogen donor. During the catalyst preparation, Sn doping reduces the size of carbon spheres, and the formation of Ni–Sn intermetallic compounds restrain the graphitization, contributing to larger pore volume and pore diameter. Consequently, a more facile mass transfer occurs in carbon-encapsulated Ni-Sn intermetallic compound catalysts than in carbon-encapsulated Ni catalysts. During the in-situ hydrothermal deoxygenation, the synergism between Ni and Sn favors palmitic acid hydrogenation to a highly reactive hexadecanal that easily either decarbonylate to n -pentadecane or is hydrogenated to hexadecanol. At high reaction temperature, hexadecanol undergoes dehydrogenation-decarbonylation, generating n -pentadecane. Also, the C-C bond hydrolysis and methanation are suppressed on Ni-Sn intermetallic compounds, favorable for increasing the carbon yield and reducing the H 2 consumption. The n -pentadecane and n -hexadecane yields reached 88.1% and 92.8% on carbon-encapsulated Ni 3 Sn 2 intermetallic compound at 330 °C. After washing and H 2 reduction, the carbon-encapsulated Ni 3 Sn 2 intermetallic compound remains stable during three recycling cycles. This is ascribed to the carbon confinement that effectively suppresses the sintering and loss of metal particles under harsh hydrothermal conditions.
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