Synthesis of ZSM-5 zeolite typically utilizes small molecule polyamines or quaternary ammonium salts as organic structure guiding agent(OSDA).By contrast,the OSDA-free hydrothermal synthesis system eliminates the use ...Synthesis of ZSM-5 zeolite typically utilizes small molecule polyamines or quaternary ammonium salts as organic structure guiding agent(OSDA).By contrast,the OSDA-free hydrothermal synthesis system eliminates the use of organic templates and the subsequent calcination procedure.This not only reduces the cost of synthesis,but also prevents environmental pollution from the combustion of organic templates,representing an eco-friendly approach.Despite this,literature suggests that even so-called template-free synthesis systems often involve trace amount of organic substances like alcohol.In the present work,a calcined commercial ZSM-5 zeolite was served as seed,with sodium aluminate as aluminum source and silica sol as silicon source,ensuring an entirely template-free synthesis system.Polycrystalline ZSM-5 aggregates consisted of rod-like nanocrystals were successfully prepared in the completely OSDA-free system.Effects of the Si/Al ratio in ZSM-5 seed,dosage and crystallization conditions such as crystallization temperature and crystallization time on ZSM-5 synthesis were investigated.The results show that a highly crystallinity ZSM-5 aggregate consisting of primary nano-sized crystals less than 100 nm is produced from a gel precursor with 5.6%(in mass)seed after hydrothermal treatment for 48 h.Furthermore,the Si/Al ratio in ZSM-5 seed has little effect on the topological structure and pore structure of the synthesized samples.However,the seeds with a low Si/Al ratio facilitate faster crystallization of zeolite and enhance the acidity,especially the strong acid centers,of the catalyst.The catalytic performance of the synthesized polycrystalline ZSM-5 was evaluated during dehydration of methanol and compared with a commercial reference ZSM-5r.The results exhibit that as compared with the reference catalyst,the fabricated sample has a longer catalytic lifetime(16 h vs 8 h)attributed to its hierarchical pores derived from the loosely packed primary nanoparticles.Additionally,the prepared polycrystalline catalyst also e展开更多
In this paper, CuO, CuO/Cu2O, Cu2O, Cu2O/Cu and Cu microcrystals were synthesized via a hydrothermal method by mixing Cu（NO3）2·3H2O and NaOH together in the presence of an ionic liquid l-butyl-3-methylimidazoli...In this paper, CuO, CuO/Cu2O, Cu2O, Cu2O/Cu and Cu microcrystals were synthesized via a hydrothermal method by mixing Cu（NO3）2·3H2O and NaOH together in the presence of an ionic liquid l-butyl-3-methylimidazolium tetrafluoroborate（[BMIM]BF4） or 1-butyl-3-methylimidazolium chloride（[BMIM]Cl）. The structures and the morphologies of the obtained products were characterized by means of X-ray diffractometer（XRD）, field-emission scanning electron microscopy/energy-dispersive spectroscopy（FESEM/EDS）, transmission electron microscopy/selected area electron diffraction（TEM/SAED） and Raman spectroscopy. The result of XRD indicates that Cu2O and Cu microcrystals are cubic phase and the Raman spectra confirm the presence of carbon. The results of FESEM and TEM images show Cu2O microcrystals as rule cubes of 2μm in length and Cu particles of 5 μm in diameter. According to the difference between crystal structures, bi-eomponent and single component products were synthesized by adjusting the reaction conditions. A possible formation mechanism of Cu2O and Cu was proposed in [BMIM]BF4.展开更多
基金National Natural Science Foundation of China(U19B2003,21706177,21975174)Foundation Supported by China Petroleum&Chemical Corporation(121014-2)。
文摘Synthesis of ZSM-5 zeolite typically utilizes small molecule polyamines or quaternary ammonium salts as organic structure guiding agent(OSDA).By contrast,the OSDA-free hydrothermal synthesis system eliminates the use of organic templates and the subsequent calcination procedure.This not only reduces the cost of synthesis,but also prevents environmental pollution from the combustion of organic templates,representing an eco-friendly approach.Despite this,literature suggests that even so-called template-free synthesis systems often involve trace amount of organic substances like alcohol.In the present work,a calcined commercial ZSM-5 zeolite was served as seed,with sodium aluminate as aluminum source and silica sol as silicon source,ensuring an entirely template-free synthesis system.Polycrystalline ZSM-5 aggregates consisted of rod-like nanocrystals were successfully prepared in the completely OSDA-free system.Effects of the Si/Al ratio in ZSM-5 seed,dosage and crystallization conditions such as crystallization temperature and crystallization time on ZSM-5 synthesis were investigated.The results show that a highly crystallinity ZSM-5 aggregate consisting of primary nano-sized crystals less than 100 nm is produced from a gel precursor with 5.6%(in mass)seed after hydrothermal treatment for 48 h.Furthermore,the Si/Al ratio in ZSM-5 seed has little effect on the topological structure and pore structure of the synthesized samples.However,the seeds with a low Si/Al ratio facilitate faster crystallization of zeolite and enhance the acidity,especially the strong acid centers,of the catalyst.The catalytic performance of the synthesized polycrystalline ZSM-5 was evaluated during dehydration of methanol and compared with a commercial reference ZSM-5r.The results exhibit that as compared with the reference catalyst,the fabricated sample has a longer catalytic lifetime(16 h vs 8 h)attributed to its hierarchical pores derived from the loosely packed primary nanoparticles.Additionally,the prepared polycrystalline catalyst also e
基金Supported by the National Natural Science Foundation of China（Nos.51104050, 51301050, 51202047）, the Natural Science Foundation of Heilongjiang Province, China（Nos.E201413, E201419）, the Technology Foundation for Selected Overseas Chinese Scholar of Heilongjiang Province, China（No. 159150130002） and the Fundamental Research Funds for the Central Universities of China（No.HEUCF161501）.
文摘In this paper, CuO, CuO/Cu2O, Cu2O, Cu2O/Cu and Cu microcrystals were synthesized via a hydrothermal method by mixing Cu（NO3）2·3H2O and NaOH together in the presence of an ionic liquid l-butyl-3-methylimidazolium tetrafluoroborate（[BMIM]BF4） or 1-butyl-3-methylimidazolium chloride（[BMIM]Cl）. The structures and the morphologies of the obtained products were characterized by means of X-ray diffractometer（XRD）, field-emission scanning electron microscopy/energy-dispersive spectroscopy（FESEM/EDS）, transmission electron microscopy/selected area electron diffraction（TEM/SAED） and Raman spectroscopy. The result of XRD indicates that Cu2O and Cu microcrystals are cubic phase and the Raman spectra confirm the presence of carbon. The results of FESEM and TEM images show Cu2O microcrystals as rule cubes of 2μm in length and Cu particles of 5 μm in diameter. According to the difference between crystal structures, bi-eomponent and single component products were synthesized by adjusting the reaction conditions. A possible formation mechanism of Cu2O and Cu was proposed in [BMIM]BF4.
