Standardization of catalyst preparation using reference catalyst: ion exchange of mordenite type zeolite: 1. Remarkable dealumination accompanying ion exchange
Standardization of catalyst preparation using reference catalyst: ion exchange of mordenite type zeolite: 1. Remarkable dealumination accompanying ion exchange
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DOI：
10.1016/j.apcata.2004.12.036
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发表时间：
2005-04
影响因子：
5.5
通讯作者：
N. Katada;T. Takeguchi;Tatsuya Suzuki;Toshihisa Fukushima;Kinya Inagaki;S. Tokunaga;H. Shimada;Koich Sato;Y. Oumi;T. Sano;K. Segawa;K. Nakai;H. Shoji;Peng Wu;T. Tatsumi;T. Komatsu;T. Masuda;K. Domen;E. Yoda;J. Kondo;T. Okuhara;Yasuyoshi Kageyama;M. Niwa;M. Ogura;M. Matsukata;E. Kikuchi;N. Okazaki;Motoi Takahashi;A. Tada;S. Tawada;Y. Kubota;Y. Sugi;Y. Higashio;M. Kamada;Yukiyo Kioka;Kohei Yamamoto;T. Shouji;Y. Arima;Y. Okamoto;H. Matsumoto
中科院分区：
文献类型：
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作者：
N. Katada;T. Takeguchi;Tatsuya Suzuki;Toshihisa Fukushima;Kinya Inagaki;S. Tokunaga;H. Shimada;Koich Sato;Y. Oumi;T. Sano;K. Segawa;K. Nakai;H. Shoji;Peng Wu;T. Tatsumi;T. Komatsu;T. Masuda;K. Domen;E. Yoda;J. Kondo;T. Okuhara;Yasuyoshi Kageyama;M. Niwa;M. Ogura;M. Matsukata;E. Kikuchi;N. Okazaki;Motoi Takahashi;A. Tada;S. Tawada;Y. Kubota;Y. Sugi;Y. Higashio;M. Kamada;Yukiyo Kioka;Kohei Yamamoto;T. Shouji;Y. Arima;Y. Okamoto;H. Matsumoto
组织了一项联合研究，以建立一套将沸石从钠离子交换成质子形式的标准条件。Si/Al_2 =ca. 15离子交换成NH 4形式，然后根据各种配方煅烧。在此基础上，采用ICP、TG、XPS、SEM、XRD、N2吸附、29 Si和27 Al NMR、苯扩散、OH和吸附吡啶及CO的IR、氨TPD等先进技术对催化剂进行了表征，并进行了异丙苯裂解、联苯异丙基化、丙烯齐聚、乙醛与氨的Chichibabin缩合合成甲基吡啶等试验反应。离子交换（除去钠）如预期进行，但观察到如此制备的质子形式样品的物理化学和催化性质的显著差异。离子交换温度过高（383 K）会导致结构退化，而在333- 353 K交换的样品大多保持了结晶度和孔体积。NH 4Cl的使用稍微改变了晶体形态。在773 K以上煅烧后，大多数样品上形成了骨架外铝物种。相比之下，在673 K煅烧保持骨架铝。因此，认为脱铝在从铵型沸石中完全除去氨之后进行。然而，质子形式的沸石在干燥条件下是稳定的，因此推测脱铝是由质子形式的沸石与具有湿度的大气接触引起的。总酸度和布朗斯特酸度随脱铝量的增加而降低，而刘易斯酸度随脱铝量的增加而增加。另一方面，铵型沸石的快速加热导致微孔变窄。这些结构变化严重影响了催化剂对各种反应的催化活性。
A joint study was organized to establish a standard set of conditions for the ion exchange of zeolite from sodium into proton-form. The sodium-form mordenite with Si/Al2=ca. 15 was ion exchanged into an NH4-form, followed by calcination according to various recipes. Then various advanced techniques for characterization (ICP, TG, XPS, SEM, XRD, N2adsorption,29Si and27Al NMR, benzene diffusion, IR of OH and adsorbed pyridine and CO, ammonia TPD) were applied, and some test reactions (cracking of cumene, isopropylation of biphenyl, oligomerization of propene and chichibabin condensation of acetaldehyde and ammonia into picoline) were conducted. The ion exchange (removal of sodium) proceeded as expected, but remarkable differences were observed in physicochemical and catalytic properties of the thus-prepared proton-form samples. Exceptionally high temperature (383K) for the ion exchange resulted in the structural degradation, while most samples exchanged at 333–353K maintained the crystallinity and pore volume. The use of NH4Cl slightly changed the crystal morphology. Extra-framework aluminum species was formed on most samples after calcination above 773K. In contrast, calcination at 673K maintained the framework aluminum. Therefore, the dealumination is considered to proceed after complete removal of ammonia from the ammonium-form zeolite. However, the proton-form zeolite was stable under dry conditions, so it is speculated that the dealumination was induced by the contact of the proton-form zeolite to atmosphere with humidity. The total and Brønsted acidity decreased with the dealumination, while Lewis acidity increased. On the other hand, rapid heating of the ammonium type zeolite caused narrowing of the micropores. These structural changes seriously affected the catalytic activities for various reactions.