Development of AEI type germanoaluminophosphate (GeAPO-18) with ultra-weak acid sites and its catalytic properties for the methanol to olefin (MTO) reaction
Development of AEI type germanoaluminophosphate (GeAPO-18) with ultra-weak acid sites and its catalytic properties for the methanol to olefin (MTO) reaction
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DOI：
10.1039/c7cy01153a
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发表时间：
2017-10
影响因子：
5
通讯作者：
Kaito Ono;K. Miyake;M. Nakai;H. Jabri;Y. Hirota;Y. Uchida;S. Tanaka;M. Miyamoto;N. Nishiyama-N.-Nishiy
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文献类型：
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作者：
Kaito Ono;K. Miyake;M. Nakai;H. Jabri;Y. Hirota;Y. Uchida;S. Tanaka;M. Miyamoto;N. Nishiyama-N.-Nishiy
沸石作为一种复杂的固体酸催化剂在化学工业中有着广泛的应用。调节分子筛的酸性对提高分子筛的催化性能和扩大其应用范围具有重要意义。在此，我们合成AEI型锗掺入磷酸铝，GeAPO-18，通过干凝胶转化法，以产生新的酸性。GeAPO-18具有比常规SAPO-18弱的布朗斯台德酸位点。为了证实Ge取代的效果，我们在GeAPO-18和常规SAPO-18上进行甲醇至烯烃（MTO）反应。GeAPO-18在MTO反应中的催化剂寿命比常规SAPO-18长。在GeAPO-18上的焦炭沉积速率比在常规SAPO-18上的慢。这些结果表明，GeAPO-18的降低的酸强度可以通过不期望的连续反应来延迟焦炭形成。在磷酸铝分子筛骨架中引入锗元素是调节酸强度的重要手段，为固体酸催化剂的设计提供了新的方向。
Zeolites have been widely applied as sophisticated solid acid catalysts in chemical industries. Tuning the acidic properties of zeolites is very important to improve their catalytic performances and expand their utilization. Herein, we synthesized AEI-type Ge-incorporated aluminophosphate, GeAPO-18, by a dry gel conversion method in order to generate new acidity. GeAPO-18 had weaker Bronsted acid sites than the conventional SAPO-18. To confirm the effect of the substitution of Ge, we carried out the methanol to olefin (MTO) reaction over GeAPO-18 and the conventional SAPO-18. The catalyst lifetime of GeAPO-18 in the MTO reaction was longer than that over the conventional SAPO-18. The rate of coke deposition on GeAPO-18 was slower than that on the conventional SAPO-18. These results indicated that the decreased acid strength of GeAPO-18 could retard the coke formation via undesired successive reactions. The incorporation of Ge into the aluminophosphate zeolite framework was a crucial method for tuning the acid strength, which provides a new direction for the design of solid acid catalysts.