Dealuminated Beta zeolite as effective bifunctional catalyst for direct transformation of glucose to 5-hydroxymethylfurfural
Dealuminated Beta zeolite as effective bifunctional catalyst for direct transformation of glucose to 5-hydroxymethylfurfural
复制标题
DOI：
10.1016/j.apcata.2013.11.012
复制
发表时间：
2014-01-30
影响因子：
5.5
通讯作者：
Tatsumi, Takashi
中科院分区：
文献类型：
--
作者：
Otomo, Ryoichi;Yokoi, Toshiyuki;Tatsumi, Takashi
为提高Beta沸石在葡萄糖直接转化为5-羟甲基糠醛（HMF）反应中的催化性能，考察了焙烧和水蒸气处理对Beta沸石骨架铝原子结构和酸性质的影响。~（27）Al MAS NMR和IR分析表明，在处理过程中，骨架中的Si-O-Al键部分断裂，形成了骨架外的Al物种，这些物种表现出刘易斯酸性。特别地，当铵型β在700 ℃以上煅烧或在500 ℃以上用蒸汽（N2平衡为50 kPa）处理时，刘易斯酸中心的量以布朗斯台德酸中心为代价而增加。发现如此制备的具有足够量的刘易斯酸位点的β沸石催化剂在由葡萄糖合成HMF中是有效的双功能催化剂;例如，通过在750 ℃煅烧制备的β沸石在78%的葡萄糖转化率下显示出55%的对HMF的选择性。我们阐明了β沸石上的刘易斯酸和布朗斯台德酸中心在葡萄糖直接转化为HMF中的作用。利用同位素实验研究了葡萄糖异构化反应的机理。最后，还考察了Beta沸石的可重复使用性。(C)2013爱思唯尔有限公司版权所有。
To improve the catalytic performance of Beta zeolite in the direct transformation of glucose into 5hydroxymethylfurfural (HMF), effects of calcination and steam treatment on the structure of Al atoms in the framework and acid properties of Beta zeolite were examined in detail. 27Al MAS NMR measurement and IR observation revealed that a part of Si-O-Al bonds in the framework were cleaved to form Al species out of the *BEA framework during the treatments and these species showed Lewis acidity. Especially, when the ammonium-type Beta was calcined over 700 degrees C or treated with steam (50 kPa in N2 balance) over 500 degrees C, the amount of Lewis acid sites was increased at the expense of Bronsted acid sites. Thus prepared Beta zeolite catalysts having a sufficient amount of Lewis acid sites were found to be effective bifunctional catalysts in synthesis of HMF from glucose; for example, Beta zeolite prepared by the calcination at 750 degrees C showed 55% selectivity to HMF at 78% conversion of glucose. We clarified the roles of Lewis and Bronsted acid sites on the Beta zeolite in the direct transformation of glucose to HMF. Furthermore, the reaction mechanism for the isomerization of glucose was investigated by means of isotope experiment using deuterated glucose. Finally, reusability of the Beta zeolite was also investigated. (C) 2013 Elsevier B.V. All rights reserved.