The role of self assembled monolayer in inducing the crystal growth was investigated by X ray diffractions (XRD), and scanning electron microscopy (SEM). Results show that crystallization in the absence of monolayer r...The role of self assembled monolayer in inducing the crystal growth was investigated by X ray diffractions (XRD), and scanning electron microscopy (SEM). Results show that crystallization in the absence of monolayer results in a mixture of poorly crystallized calcium phosphates, including hydroxyapatite (HAP) and octacalcium phosphate (OCP), while the presence of self assembled monolayer gives rise to oriented and well crystallized HAP crystals. Moreover, the HAP crystal grows very quickly under the self assembled monolayer, whereas very little calcium phosphate crystals grow without the monolayer. It is rationalized that the hexadecylamine monolayer with high polarity and charged density leads to increase supersaturation and lower the interfacial energy, which attributes to the HAP crystals nucleation. On the other hand, the positive headgroups construct the ordered "recognized site" with distinct size and topology, which results in the oriented HAP crystals deposit.展开更多
The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer products.Here,...The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer products.Here,based on the potential crystallization principle of calcium sulfate in NH_(4)NO_(3)-H_(3)PO_(4)-H_(2)O,the deep decalcification(i.e.calcium removal)technology to achieveα-high-strength gypsum originated from freezing acidolysis-solutions has been firstly proposed and investigated.Typically,calcium can be removed from the factory-provided freezing acidolysis-solution by neutralizing it with ammonia,followed by the addition of ammonium sulfate solution.As a result,the formation of calcium sulfate in the reaction system undergoes the nucleation and growth of CaSO_(4)·2H_(2)O(DH),as well as its dissolution and crystallization into short columnarα-CaSO_(4)·0.5H_(2)O(α-HH).Remarkably,with the molar ratio of SO_(4)^(2-)/Ca^(2+)at 1.8,the degree of neutralization(NH_(3)/HNO_(3) molar ratio)at 1.7,the reaction temperature of 94℃,and the reaction time of 300 min,the decalcification rate can reach 86.89%,of which the high-strengthα-CaSO_(4)·0.5H_(2)O(α-HH)will be obtained.Noteworthy,the deep decalcification product meets the standards for the production of fine phosphates and highly water-soluble phosphate fertilizers.Consequently,the 2 h flexural strength ofα-HH is 5.3 MPa and the dry compressive strength is 36.8 MPa,which is up to the standard of commercialα-HH.展开更多
Development of a titanium silicalite-1(TS-1)catalyst with good crystallinity and a four-coordinate Ti framework is critical for efficient catalytic oxidation reaction under mild conditions.Herein,a size-controlled TS-...Development of a titanium silicalite-1(TS-1)catalyst with good crystallinity and a four-coordinate Ti framework is critical for efficient catalytic oxidation reaction under mild conditions.Herein,a size-controlled TS-1 zeolite(TS-10.1ACh(acetylcholine))was synthesized via steam-assisted crystallization by introducing acetylcholine as a crystal growth modifier in the preparation process,and TS-10.1ACh was also employed in epoxidations of different substrates containing C=C double bonds.The crystalline sizes of the as-synthesized TS-10.1ACh catalysts were controlled with the acetylcholine content,and characterization results showed that the particle sizes of highly crystalline TS-10.1ACh zeolite reached 3.0μm with a good Ti framework.Throughout the synthetic process,the growth rate of the crystals was accelerated by electrostatic interactions between the connected hydroxyl groups of the acetylcholine modifier and the negatively charged skeleton of the pre-zeolites.Furthermore,the TS-10.1ACh catalyst demonstrated maximum catalytic activity,good selectivity and high stability during epoxidation of allyl chloride.Importantly,the TS-10.1ACh catalyst was also highly versatile and effective with different unsaturated substrates.These findings may provide novel,easily separable and large TS-1 catalysts for efficient and clean industrial epoxidations of C=C double bonds.展开更多
As the byproduct of TiO2 industrial production, impure FeSO4.7H2O was used for the synthesis of LiFePO4. With the purified solution of FeSO4-7H2O, FePO4.xH2O was prepared by a normal titration method and a controlled ...As the byproduct of TiO2 industrial production, impure FeSO4.7H2O was used for the synthesis of LiFePO4. With the purified solution of FeSO4-7H2O, FePO4.xH2O was prepared by a normal titration method and a controlled crystallization method, respectively. Then LiFePO4 materials were synthesized by calcining the mixture of FePO4,xH2O, LizCO3, and glucose at 700℃ for 10 h in flowing Ar. The results indicate that the elimination of FeSO4.TH2O impurities reached over 95%, and using FePO4-xH2O prepared by the controlled crystallization method, the obtained LiFePO4 material has fine and sphere-like particles. The material delivers a higher initial discharge specific capacity of 149 mAh.g^-1 at a current density of 0.1C rate （1C = 170 mA.g^-0）; the discharge specific capacity also maintains above 120 rnAh.g^-1 after 100 cycles even at 2C rate. Thus, the employed processing is promising for easy control, low cost of raw material, and high electrochemical performance of the prepared material.展开更多
文摘The role of self assembled monolayer in inducing the crystal growth was investigated by X ray diffractions (XRD), and scanning electron microscopy (SEM). Results show that crystallization in the absence of monolayer results in a mixture of poorly crystallized calcium phosphates, including hydroxyapatite (HAP) and octacalcium phosphate (OCP), while the presence of self assembled monolayer gives rise to oriented and well crystallized HAP crystals. Moreover, the HAP crystal grows very quickly under the self assembled monolayer, whereas very little calcium phosphate crystals grow without the monolayer. It is rationalized that the hexadecylamine monolayer with high polarity and charged density leads to increase supersaturation and lower the interfacial energy, which attributes to the HAP crystals nucleation. On the other hand, the positive headgroups construct the ordered "recognized site" with distinct size and topology, which results in the oriented HAP crystals deposit.
基金supported by the National Key Research and Development Program of China(2018YFC1900206-2)Science&Technology Plan Projects of Guizhou Province(Qiankehe Service Enterprises[2018]4011)Science and Technology Support Plan Project of Guizhou Provincial:Qiankehe Support[2021]General 487。
文摘The freezing acidolysis solution of the nitric acid-phosphate fertilizer process has a high calcium content,which makes it difficult to produce fine phosphate and high water-soluble phosphate fertilizer products.Here,based on the potential crystallization principle of calcium sulfate in NH_(4)NO_(3)-H_(3)PO_(4)-H_(2)O,the deep decalcification(i.e.calcium removal)technology to achieveα-high-strength gypsum originated from freezing acidolysis-solutions has been firstly proposed and investigated.Typically,calcium can be removed from the factory-provided freezing acidolysis-solution by neutralizing it with ammonia,followed by the addition of ammonium sulfate solution.As a result,the formation of calcium sulfate in the reaction system undergoes the nucleation and growth of CaSO_(4)·2H_(2)O(DH),as well as its dissolution and crystallization into short columnarα-CaSO_(4)·0.5H_(2)O(α-HH).Remarkably,with the molar ratio of SO_(4)^(2-)/Ca^(2+)at 1.8,the degree of neutralization(NH_(3)/HNO_(3) molar ratio)at 1.7,the reaction temperature of 94℃,and the reaction time of 300 min,the decalcification rate can reach 86.89%,of which the high-strengthα-CaSO_(4)·0.5H_(2)O(α-HH)will be obtained.Noteworthy,the deep decalcification product meets the standards for the production of fine phosphates and highly water-soluble phosphate fertilizers.Consequently,the 2 h flexural strength ofα-HH is 5.3 MPa and the dry compressive strength is 36.8 MPa,which is up to the standard of commercialα-HH.
基金supported by the financial support from the National Natural Science Foundation of China(Grant Nos.21802055 and 32160537)Jiangxi Provincial Natural Science Foundation(Grant No.20202BABL205013)Jiangxi Provincial Department of Education Foundation(Grant No.GJJ190179).
文摘Development of a titanium silicalite-1(TS-1)catalyst with good crystallinity and a four-coordinate Ti framework is critical for efficient catalytic oxidation reaction under mild conditions.Herein,a size-controlled TS-1 zeolite(TS-10.1ACh(acetylcholine))was synthesized via steam-assisted crystallization by introducing acetylcholine as a crystal growth modifier in the preparation process,and TS-10.1ACh was also employed in epoxidations of different substrates containing C=C double bonds.The crystalline sizes of the as-synthesized TS-10.1ACh catalysts were controlled with the acetylcholine content,and characterization results showed that the particle sizes of highly crystalline TS-10.1ACh zeolite reached 3.0μm with a good Ti framework.Throughout the synthetic process,the growth rate of the crystals was accelerated by electrostatic interactions between the connected hydroxyl groups of the acetylcholine modifier and the negatively charged skeleton of the pre-zeolites.Furthermore,the TS-10.1ACh catalyst demonstrated maximum catalytic activity,good selectivity and high stability during epoxidation of allyl chloride.Importantly,the TS-10.1ACh catalyst was also highly versatile and effective with different unsaturated substrates.These findings may provide novel,easily separable and large TS-1 catalysts for efficient and clean industrial epoxidations of C=C double bonds.
基金supported by the National Key Technology R & D Program of China (No.2007BAE12B01-1)the National Natural Science Foundation of China (No.50604018)
文摘As the byproduct of TiO2 industrial production, impure FeSO4.7H2O was used for the synthesis of LiFePO4. With the purified solution of FeSO4-7H2O, FePO4.xH2O was prepared by a normal titration method and a controlled crystallization method, respectively. Then LiFePO4 materials were synthesized by calcining the mixture of FePO4,xH2O, LizCO3, and glucose at 700℃ for 10 h in flowing Ar. The results indicate that the elimination of FeSO4.TH2O impurities reached over 95%, and using FePO4-xH2O prepared by the controlled crystallization method, the obtained LiFePO4 material has fine and sphere-like particles. The material delivers a higher initial discharge specific capacity of 149 mAh.g^-1 at a current density of 0.1C rate （1C = 170 mA.g^-0）; the discharge specific capacity also maintains above 120 rnAh.g^-1 after 100 cycles even at 2C rate. Thus, the employed processing is promising for easy control, low cost of raw material, and high electrochemical performance of the prepared material.
