The relationship between dissolution rate and pH is determined by carrying out dynamic experiments of hedenbergite and grossularite dissolution .The dissolution reaction equations are established .The dissolution proc...The relationship between dissolution rate and pH is determined by carrying out dynamic experiments of hedenbergite and grossularite dissolution .The dissolution reaction equations are established .The dissolution processes of two minerals are simulated by using the theory of multi-phase and mufti-component chemical equilibrium . The results bring light to the mechanism of dissolution processes .Due to incongruent dissolution of two minerals when the dissolution processes reach a metastable supersaturation critical point new metastable minerals can be formed in the system .The experiments showed that dissolution of grossularite and hedenbergite consumes H+ and then makes pH value of solution high . In turn , precipitation of metastable minerals makes pH value low .Precipitation of metastable minerals has a catalytic effect for dissolution of reacting minerals in special time .Precipitation and dissolution carried out alternately in the system and it causes periodic oscillation of pH values with reacting time . This is the dissipative structure or self-organization happened in the processes of mineral dissolution.展开更多
The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an e...The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1(MFI)zeolites by replacing tetrabutyl orthotitanate(TBOT)with tetrabutyl orthotitanate tetramer(TBOT-tetramer)as the titanium source.The introduced TBOT-tetramer slowed down the zeolite crystallization process,and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species.Notably,the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40.The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area.It also impeded the formation of anatase species,resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.展开更多
The effects of corrosion temperature, oxygen flow rate and corrosion time on the transformation of metallic iron were systematically studied, and the effects of mineral phases of Fe-bearing products on Ti-Fe separatio...The effects of corrosion temperature, oxygen flow rate and corrosion time on the transformation of metallic iron were systematically studied, and the effects of mineral phases of Fe-bearing products on Ti-Fe separation were investigated. The reaction mechanism of metallic iron in corrosion process was proposed. The results showed that corrosion temperature played a key role in determining the transformation of metallic iron in reduced ilmenite during corrosion process. Under suitable corrosion conditions, Fe-bearing mineral in reduced ilmenite could be converted to amorphous ferric hydroxide, lepidocrocite,hematite and magnetite, respectively, and lepidocrocite was the most easily separated Fe-bearing mineral from corrosion products owing to the significant density difference between lepidocrocite and Ti-rich materials. The Ti-rich material with 77.81 wt.% TiO2 and Fe-bearing product with 52.69 wt.% total Fe were obtained by gravity separation. The Ti recovery ratio and Fe recovery ratio were 91.16% and 86.27%, respectively.展开更多
基金The project is supported by the National Nature Science Foundation of China
文摘The relationship between dissolution rate and pH is determined by carrying out dynamic experiments of hedenbergite and grossularite dissolution .The dissolution reaction equations are established .The dissolution processes of two minerals are simulated by using the theory of multi-phase and mufti-component chemical equilibrium . The results bring light to the mechanism of dissolution processes .Due to incongruent dissolution of two minerals when the dissolution processes reach a metastable supersaturation critical point new metastable minerals can be formed in the system .The experiments showed that dissolution of grossularite and hedenbergite consumes H+ and then makes pH value of solution high . In turn , precipitation of metastable minerals makes pH value low .Precipitation of metastable minerals has a catalytic effect for dissolution of reacting minerals in special time .Precipitation and dissolution carried out alternately in the system and it causes periodic oscillation of pH values with reacting time . This is the dissipative structure or self-organization happened in the processes of mineral dissolution.
基金the National Natural Science Foundation of China, China (Grant 21920102005, 22288101, and 21835002)the 111 Project, China (B17020)+2 种基金the European Union through the European Research Council, European Union (grant ERC-AdG-2014-671093, SynCatMatch)the Spanish Government through “Severo Ochoa”, Spain (SEV2016-0683, MINECO) for supporting this workthe financial support from China Scholarship Council, China
文摘The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions.Herein,we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1(MFI)zeolites by replacing tetrabutyl orthotitanate(TBOT)with tetrabutyl orthotitanate tetramer(TBOT-tetramer)as the titanium source.The introduced TBOT-tetramer slowed down the zeolite crystallization process,and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species.Notably,the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40.The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area.It also impeded the formation of anatase species,resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.
基金the Natural Science Foundation of Hunan Province,China(Grant No.2019JJ50816)the National Natural Science Foundation of China(Grant No.50504018)supporting this research,and they acknowledge the support of State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization.
文摘The effects of corrosion temperature, oxygen flow rate and corrosion time on the transformation of metallic iron were systematically studied, and the effects of mineral phases of Fe-bearing products on Ti-Fe separation were investigated. The reaction mechanism of metallic iron in corrosion process was proposed. The results showed that corrosion temperature played a key role in determining the transformation of metallic iron in reduced ilmenite during corrosion process. Under suitable corrosion conditions, Fe-bearing mineral in reduced ilmenite could be converted to amorphous ferric hydroxide, lepidocrocite,hematite and magnetite, respectively, and lepidocrocite was the most easily separated Fe-bearing mineral from corrosion products owing to the significant density difference between lepidocrocite and Ti-rich materials. The Ti-rich material with 77.81 wt.% TiO2 and Fe-bearing product with 52.69 wt.% total Fe were obtained by gravity separation. The Ti recovery ratio and Fe recovery ratio were 91.16% and 86.27%, respectively.
