The ZSM-22 and ZSM-35 zeolites were synthesized via the hydrothermal crystallization method. The samples were characterized by XRD, SEM, N_2 adsorption-desorption, NH_3-TPD, TPO, TG, and Raman spectrometry, and the re...The ZSM-22 and ZSM-35 zeolites were synthesized via the hydrothermal crystallization method. The samples were characterized by XRD, SEM, N_2 adsorption-desorption, NH_3-TPD, TPO, TG, and Raman spectrometry, and the results showed that ZSM-22 and ZSM-35 possessed similar microporous volume and acidity. In the alkylation of benzene with methanol, ZSM-22 and ZSM-35 showed different coke location, coking rate and graphitizing degree. Compared with the industrial ZSM-5, ZSM-22 and ZSM-35 both showed higher selectivity of toluene and xylene(93.63% and 96.50%,respectively) during the alkylation of benzene with methanol, and the selectivity of para-xylene in xylene isomers was51.96% and 41.45%, respectively. Meanwhile, the selectivity of ethylbenzene and C_9^+ aromatics was also lower than that of industrial ZSM-5.展开更多
The enthalpies of formation of some compounds are not easy to be measured experimentally. This paper reports the calculated values of the heat of formation for some novel moleclar sieves by a rnethod of consistant mol...The enthalpies of formation of some compounds are not easy to be measured experimentally. This paper reports the calculated values of the heat of formation for some novel moleclar sieves by a rnethod of consistant molecular mechanics force field.The enthalpies of formation of novel type molecular sieves: ZSM-48, ZSM-22, ZSM-23 and ZSM-18, have been calculated.展开更多
ZSM‐22 zeolite with different crystal lengths was prepared using a modified hydrothermal method. Rotation speed, Si/Al molar ratio and co‐solvent have important effects on the crystal size of ZSM‐22. The nanosized ...ZSM‐22 zeolite with different crystal lengths was prepared using a modified hydrothermal method. Rotation speed, Si/Al molar ratio and co‐solvent have important effects on the crystal size of ZSM‐22. The nanosized zeolite samples were characterized by X‐ray diffraction, X‐ray fluorescence, nitrogen adsorption, scanning electron microscopy, temperature‐programmed desorption of am‐monia and solid state nuclear magnetic resonance. The catalytic performance of nanosized ZSM‐22 was tested using the conversion of methanol. Compared to conventional ZSM‐22, the nanosized ZSM‐22 zeolite exhibited superior selectivity to ethylene and aromatics and lower selectivity to propylene. Stability against deactivation was clearly shown by the nanosized ZSM‐22 zeolite. A higher external surface area and smaller particle size make this nanosized ZSM‐22 zeolite attractive for catalytic applications.展开更多
ZSM-22 was synthesized using various sources of silica, organic template 1,6-diaminohexane, under hydrothermal conditions, with and without agitation during crystallization. Subsequently, the crystallized material was...ZSM-22 was synthesized using various sources of silica, organic template 1,6-diaminohexane, under hydrothermal conditions, with and without agitation during crystallization. Subsequently, the crystallized material was used as seeds to accelerate the crystallization process. Characterization of the ZSM-22 samples was performed by XRD, ATG/DTG and FT-IR. It was found that it is possible to synthesize ZSM-22 employing colloidal silica and pyrolytic silica as silicon sources only if the system is stirred during crystallization. The crystallization time for these systems was 13 hours, longer times of crystallization do not significantly increase the crystallinity of the sample. The addition of seeds significantly accelerates the crystallization of ZSM-22, reducing the crystallization time to only 7 hours, with stirring and with systems employing colloidal silica.展开更多
基金financial support from the National Natural Science Foundation of China (No.2177061270)
文摘The ZSM-22 and ZSM-35 zeolites were synthesized via the hydrothermal crystallization method. The samples were characterized by XRD, SEM, N_2 adsorption-desorption, NH_3-TPD, TPO, TG, and Raman spectrometry, and the results showed that ZSM-22 and ZSM-35 possessed similar microporous volume and acidity. In the alkylation of benzene with methanol, ZSM-22 and ZSM-35 showed different coke location, coking rate and graphitizing degree. Compared with the industrial ZSM-5, ZSM-22 and ZSM-35 both showed higher selectivity of toluene and xylene(93.63% and 96.50%,respectively) during the alkylation of benzene with methanol, and the selectivity of para-xylene in xylene isomers was51.96% and 41.45%, respectively. Meanwhile, the selectivity of ethylbenzene and C_9^+ aromatics was also lower than that of industrial ZSM-5.
文摘The enthalpies of formation of some compounds are not easy to be measured experimentally. This paper reports the calculated values of the heat of formation for some novel moleclar sieves by a rnethod of consistant molecular mechanics force field.The enthalpies of formation of novel type molecular sieves: ZSM-48, ZSM-22, ZSM-23 and ZSM-18, have been calculated.
基金supported by the National Natural Science Foundation of China (21506202)~~
文摘ZSM‐22 zeolite with different crystal lengths was prepared using a modified hydrothermal method. Rotation speed, Si/Al molar ratio and co‐solvent have important effects on the crystal size of ZSM‐22. The nanosized zeolite samples were characterized by X‐ray diffraction, X‐ray fluorescence, nitrogen adsorption, scanning electron microscopy, temperature‐programmed desorption of am‐monia and solid state nuclear magnetic resonance. The catalytic performance of nanosized ZSM‐22 was tested using the conversion of methanol. Compared to conventional ZSM‐22, the nanosized ZSM‐22 zeolite exhibited superior selectivity to ethylene and aromatics and lower selectivity to propylene. Stability against deactivation was clearly shown by the nanosized ZSM‐22 zeolite. A higher external surface area and smaller particle size make this nanosized ZSM‐22 zeolite attractive for catalytic applications.
文摘ZSM-22 was synthesized using various sources of silica, organic template 1,6-diaminohexane, under hydrothermal conditions, with and without agitation during crystallization. Subsequently, the crystallized material was used as seeds to accelerate the crystallization process. Characterization of the ZSM-22 samples was performed by XRD, ATG/DTG and FT-IR. It was found that it is possible to synthesize ZSM-22 employing colloidal silica and pyrolytic silica as silicon sources only if the system is stirred during crystallization. The crystallization time for these systems was 13 hours, longer times of crystallization do not significantly increase the crystallinity of the sample. The addition of seeds significantly accelerates the crystallization of ZSM-22, reducing the crystallization time to only 7 hours, with stirring and with systems employing colloidal silica.
