Orchestrating fluoride effect, secondary growth and microwave irradiation in the synthesis of EU-1/ZSM-48 intergrowth crystals for the conversion of dimethyl ether to olefins
Orchestrating fluoride effect, secondary growth and microwave irradiation in the synthesis of EU-1/ZSM-48 intergrowth crystals for the conversion of dimethyl ether to olefins
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DOI：
10.1016/j.micromeso.2018.02.047
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发表时间：
2018-09
影响因子：
5.2
通讯作者：
Mohamed H. M. Ahmed;O. Muraza;K. Miyake;Y. Hirota;N. Nishiyama
中科院分区：
文献类型：
--
作者：
Mohamed H. M. Ahmed;O. Muraza;K. Miyake;Y. Hirota;N. Nishiyama
在碱性介质中，加入10%的EU-1晶种，将微波辅助水热合成与添加氟化物晶化促进剂相耦合，可使EU-1沸石的晶化时间大大缩短至10 h。有趣的表征结果，通过观察八面体配位的Al与氟化物在合成中提出的AlO 4F 2的形式。这一发现通过分析FTIR和27 Al MAS NMR光谱得到证实，其中显示了归因于AlO 4F 2的额外峰。短的结晶时间提供了一个显着的减少，EU-1的颗粒尺寸为1500 nm，如FE-SEM上观察到的。在Si/Al比为25-100范围内合成了纯相EU-1。在制备200硅铝比凝胶时，XRD观察到EU-1和ZSM-48的共生相。在EU-1和ZSM-48共晶样品上实现了优异的二甲醚转化为烯烃的催化性能。与其他样品相比，该样品在360 min内表现出优异的稳定性，烯烃选择性最高，达到78%。
A great decrease in the crystallization time of EU-1 zeolite to 10 h was achieved by coupling between the microwave-assisted hydrothermal synthesis and the addition of fluoride as crystallization promoter in the presence of 10% EU-1 seeds in alkaline media. Interesting characterization results were obtained by observing an octahedral coordination of Al incorporated with the fluoride presented in the synthesis in the form of AlO4F2. This finding was confirmed by analyzing the spectra of FTIR and27Al MAS NMR which showed additional peak attributed to AlO4F2. The short crystallization time offered a significant decrease of EU-1 particle size to ∼500 nm as observed on FE-SEM. A pure phase of EU-1 was synthesized in the range of 25–100 Si/Al ratio. An intergrowth phase of EU-1 and ZSM-48 was observed on XRD when 200 Si/Al ratio gel was prepared. Excellent catalytic performance of DME conversion to olefins was achieved over the co-crystalline EU-1 and ZSM-48 sample. The sample showed exceptional stability for 360 min on stream compared with other samples and the highest olefins selectivity which reached to 78%.