利用微波辐射对ZSM-35分子筛催化剂进行碱处理,将得到的改性催化剂采用XRD,N2物理吸附-脱附,NH3-TPD,红外谱图进行表征,同时应用于二甲醚(DME)羰基化反应。结果表明,微波碱处理可清洗分子筛微孔孔道内无定形物种,提高八元环内的总酸量,使得改性后的分子筛催化剂上DME转化率较未改性的ZSM-35均有一定程度的提高,同时有效抑制催化剂的积炭,但醋酸甲酯的选择性变化不明显。与常规水热碱处理相比,在达到相似的反应性能条件下,微波辐射可以缩短碱处理时间。催化剂反应性能不仅与八元环的酸量有关,还与孔道扩散性能相关。
Alkaline treatment under microwave irradiation was applied to modifying ZSM-35 zeolite catalyst. The modified catalysts were characterized by XRD, N2 absorption-desorption, NHz-TPD and Py-IR, and used for carbonylation reaction of dimethyl ether (DME). The results showed that microwave-assisted alkaline treatment could remove the amorphous species from the zeolite channel and increase the acidity density in eight-membered rings of the zeolite, which resulted in the increase of DME conversion and the lower coke deposition in the reaction, but no obvious change for the selectivity to methyl acetate. To achieve a similar catalytic performance, the time required for the microwave-assisted alkaline treatment of ZSM-35 was shorter than that for the conventional alkaline hydrothermal treatment. The catalytic activity of ZSM-35 zeolite was related not only to the acidity density in eight-membered rings but also to the diffusion properties of the zeolite.