A novel SnO2-based gas anode was developed for aluminum electrolysis in molten cryolite at 850 ＆#176;C to reduce energy consumption and decrease CO2 emissions. Hydrogen was introduced into the anode, participating in...A novel SnO2-based gas anode was developed for aluminum electrolysis in molten cryolite at 850 ＆#176;C to reduce energy consumption and decrease CO2 emissions. Hydrogen was introduced into the anode, participating in the anode reaction. Carbon and aluminum were used as the cathode and reference electrodes, respectively. Cyclic voltammetry was applied in the cell to investigate the electrochemical behavior of oxygen ion on platinum and SnO2-based materials. The potential for oxygen evolution on these electrode materials was determined. Then, galvanostatic electrolysis was performed on the gas anode, showing a significant depolarization effect （a decrease of ~0.8 V of the anode potential） after the introduction of hydrogen, compared with no gas introduction or the introduction of argon. The results indicate the involvement of hydrogen in the anode reaction （three-phase-boundary reaction including gas, electrolyte and electrode） and give the possibility for the utilization of reducing gas anodes for aluminum electrolysis.展开更多
The removal of hydrogen sulfide from gas plays an important role in rational utilization of resources and environ- mental protection. In this paper, the process of hydrogen sulfide removal by wet oxidation method in a...The removal of hydrogen sulfide from gas plays an important role in rational utilization of resources and environ- mental protection. In this paper, the process of hydrogen sulfide removal by wet oxidation method in a rotating packed bed was investigated in a scale for treating 10 000 Nm3/h of gas. On the basis of studying the influence of the species and con- centration of alkali source, the liquid/gas volume ratio, the high gravity factor, and the hydrogen sulfide content in feed gas on the desulfurization effect, the suitable technological conditions were obtained. The hydrogen sulfide removal efficiency could reach 98.0% under these conditions. The results of continuous operation of process facilities showed that the high gravity method has many merits including higher desulfurization rate, good stability in operation, lower liquid/gas volume ratio, greater operation elasticity, and apparent energy saving effects.展开更多
In this study, bamboo scaffolding was used to produce activated carbon by carbonization at 600 ℃ and 900 ℃with the purge of nitrogen. The 600 ℃ char was then further modified chemically by acids and alkalis by refl...In this study, bamboo scaffolding was used to produce activated carbon by carbonization at 600 ℃ and 900 ℃with the purge of nitrogen. The 600 ℃ char was then further modified chemically by acids and alkalis by reflux for 6 hours. The produced chars were then characterized by nitrogen adsorption isotherm, He pyncometry, pH, elemental analysis and Boehm titration. For most of the chemically modified carbons, the micropore surface areas and volumes have increased compared with the 600 ~C char, while the mesopore surface areas and volumes slightly decreased, which may have been due to the dissolving of some of the permeated inorganic matter and oxidizing deposited carbon that blocks the pore openings. For the acidic modified carbons, larger amounts of acidic groups were present in the carbons after being activated by phosphoric acid, phosphoric acid furth, er treated with 2 mol-L-1nitric-acid, and calcium hydroxide. Although carbon treated with 2 mol.L-1 and 5 mol·L-1 nitric acid also produced high acidity, the surface areas and pore volumes were relatively low, due to the destruction of pores by nitric acid oxidation. The reduction of porosity may impair the adsorption capacity.展开更多
H2 generation from a thermochemical water-splitting reaction was performed using a sol-gel derived Ni-ferrite. The sol-gel synthesis involved addition of nickel chloride hexahydrate （NiCl2@6H2O） and ferrous chloride...H2 generation from a thermochemical water-splitting reaction was performed using a sol-gel derived Ni-ferrite. The sol-gel synthesis involved addition of nickel chloride hexahydrate （NiCl2@6H2O） and ferrous chloride tetrahydrate （FeCl2·4H2O） in ethanol followed by gelation using propylene oxide. The gels were aged, dried and calcined at 900 ℃in air or N2 environment. The powders thus obtained were characterized using X-ray diffraction （XRD）. This analysis revealed a nominally phase pure Ni-ferrite （NiFe204） composition for the gels calcined in air, whereas those calcined in N2 environment exhibited primarily Ni04Fe2.604 composition mixed with metallic Ni. Particle size and specific surface area （SSA） of the ferrite powders were analyzed using scanning electron microscopy （SEM） and Brauner-Emmett-Teller （BET） surface area analyzer, respectively. The ferrites were placed in a packed bed reactor and water-splitting reaction was carried out at 700 ℃, 800 ℃, and 900 ℃. After water-splitting reaction, oxidized ferrites were regenerated at 900 ℃ for 2 h in N2 environment. Together water-splitting and regeneration steps designated as one thermochemical cycle. In four consecutive thermochemical cycles performed using NiFe204, an average of 40 mL of H2/g per cycle was generated at water-splitting temperature of 900 ℃, which was about five times higher than the average H2 produced at 700 ℃.展开更多
基金Project(51404001)supported by the National Natural Science Foundation of ChinaProject([2014]1685)supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,China
文摘A novel SnO2-based gas anode was developed for aluminum electrolysis in molten cryolite at 850 ＆#176;C to reduce energy consumption and decrease CO2 emissions. Hydrogen was introduced into the anode, participating in the anode reaction. Carbon and aluminum were used as the cathode and reference electrodes, respectively. Cyclic voltammetry was applied in the cell to investigate the electrochemical behavior of oxygen ion on platinum and SnO2-based materials. The potential for oxygen evolution on these electrode materials was determined. Then, galvanostatic electrolysis was performed on the gas anode, showing a significant depolarization effect （a decrease of ~0.8 V of the anode potential） after the introduction of hydrogen, compared with no gas introduction or the introduction of argon. The results indicate the involvement of hydrogen in the anode reaction （three-phase-boundary reaction including gas, electrolyte and electrode） and give the possibility for the utilization of reducing gas anodes for aluminum electrolysis.
基金the Shanxi Provin-cial Youth Science and Technology Research Fund (No.2008021009-2) for the financial support to this project
文摘The removal of hydrogen sulfide from gas plays an important role in rational utilization of resources and environ- mental protection. In this paper, the process of hydrogen sulfide removal by wet oxidation method in a rotating packed bed was investigated in a scale for treating 10 000 Nm3/h of gas. On the basis of studying the influence of the species and con- centration of alkali source, the liquid/gas volume ratio, the high gravity factor, and the hydrogen sulfide content in feed gas on the desulfurization effect, the suitable technological conditions were obtained. The hydrogen sulfide removal efficiency could reach 98.0% under these conditions. The results of continuous operation of process facilities showed that the high gravity method has many merits including higher desulfurization rate, good stability in operation, lower liquid/gas volume ratio, greater operation elasticity, and apparent energy saving effects.
基金the support of Hong Kong University of Science and Technology through the Undergraduate Research Opportunity Program
文摘In this study, bamboo scaffolding was used to produce activated carbon by carbonization at 600 ℃ and 900 ℃with the purge of nitrogen. The 600 ℃ char was then further modified chemically by acids and alkalis by reflux for 6 hours. The produced chars were then characterized by nitrogen adsorption isotherm, He pyncometry, pH, elemental analysis and Boehm titration. For most of the chemically modified carbons, the micropore surface areas and volumes have increased compared with the 600 ~C char, while the mesopore surface areas and volumes slightly decreased, which may have been due to the dissolving of some of the permeated inorganic matter and oxidizing deposited carbon that blocks the pore openings. For the acidic modified carbons, larger amounts of acidic groups were present in the carbons after being activated by phosphoric acid, phosphoric acid furth, er treated with 2 mol-L-1nitric-acid, and calcium hydroxide. Although carbon treated with 2 mol.L-1 and 5 mol·L-1 nitric acid also produced high acidity, the surface areas and pore volumes were relatively low, due to the destruction of pores by nitric acid oxidation. The reduction of porosity may impair the adsorption capacity.
文摘H2 generation from a thermochemical water-splitting reaction was performed using a sol-gel derived Ni-ferrite. The sol-gel synthesis involved addition of nickel chloride hexahydrate （NiCl2@6H2O） and ferrous chloride tetrahydrate （FeCl2·4H2O） in ethanol followed by gelation using propylene oxide. The gels were aged, dried and calcined at 900 ℃in air or N2 environment. The powders thus obtained were characterized using X-ray diffraction （XRD）. This analysis revealed a nominally phase pure Ni-ferrite （NiFe204） composition for the gels calcined in air, whereas those calcined in N2 environment exhibited primarily Ni04Fe2.604 composition mixed with metallic Ni. Particle size and specific surface area （SSA） of the ferrite powders were analyzed using scanning electron microscopy （SEM） and Brauner-Emmett-Teller （BET） surface area analyzer, respectively. The ferrites were placed in a packed bed reactor and water-splitting reaction was carried out at 700 ℃, 800 ℃, and 900 ℃. After water-splitting reaction, oxidized ferrites were regenerated at 900 ℃ for 2 h in N2 environment. Together water-splitting and regeneration steps designated as one thermochemical cycle. In four consecutive thermochemical cycles performed using NiFe204, an average of 40 mL of H2/g per cycle was generated at water-splitting temperature of 900 ℃, which was about five times higher than the average H2 produced at 700 ℃.
