Disproportionation of hydrogen peroxide into singlet oxygen catalyzed by lanthanum-exchanged zeolites
Disproportionation of hydrogen peroxide into singlet oxygen catalyzed by lanthanum-exchanged zeolites
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DOI：
10.1016/j.jcat.2005.05.013
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发表时间：
2005-07
影响因子：
7.3
通讯作者：
J. Wahlen;Sigrid De Hertogh;D. Vos;V. Nardello;S. Bogaert;J. Aubry;P. Alsters;P. Jacobs
中科院分区：
文献类型：
--
作者：
J. Wahlen;Sigrid De Hertogh;D. Vos;V. Nardello;S. Bogaert;J. Aubry;P. Alsters;P. Jacobs
通过简单的阳离子交换将镧（III）固定在各种沸石载体上。测试了所得材料在H2 O2分解为单线态分子氧（1 O2）中的反应。H_2O_2反硝化反应的速率和生成的1O_2与香茅醇作为典型的烯烃底物的反应强烈地依赖于沸石的拓扑结构和组成。具有大的晶体尺寸、小的孔或一维孔系统的沸石在H2 O2的反硝化中表现出低活性。与此相反，沸石具有小的晶体尺寸或沸石具有大的交叉孔是积极的1 O2发电机。超稳Y型分子筛（USY）和Beta型分子筛负载的La被认为是活性最高、效率最高的催化剂。通常，在40 °C下24小时内，每摩尔负载在USY沸石上的La产生100摩尔香茅醇氢过氧化物。在这段时间内，800摩尔的H2 O2被分解成1 O2。与未负载的氢氧化镧相比，La-USY显示出显著更高的活性和稍微更有效地利用H2 O2。通过过滤实验验证了La-USY催化剂的多相性，并通过X射线衍射和循环实验证明了其稳定性。最后，将该催化剂用于各种烯烃化合物的过氧化反应。与传统的双金属氧化物催化剂相比，La-USY催化剂对烯丙醇衍生物的选择性过氧化反应特别有用，几乎没有竞争性环氧化反应，也没有醇的氧化反应。
Lanthanum(III) was immobilized on various zeolite supports by simple cation exchange. The resulting materials were tested in the disproportionation of H2O2into singlet molecular oxygen (1O2). The rate of H2O2disproportionation and the reaction of the formed1O2with citronellol as a typical olefinic substrate were strongly dependent on the zeolite topology and composition. Zeolites with a large crystal size, small pores, or a one-dimensional pore system showed low activity in the disproportionation of H2O2. In contrast, zeolites with a small crystal size or zeolites possessing large intersecting pores were active1O2generators. La supported on ultrastable Y zeolite (USY) and zeolite Beta were identified as the most active and efficient catalysts. Typically, within 24 h at 40 °C, 100 mol of citronellol hydroperoxides is produced per mol of La supported on USY zeolite. Within this time, 800 mol of H2O2is disproportionated into1O2. In comparison with unsupported La-hydroxide, La-USY shows a significantly higher activity and a slightly more efficient use of H2O2. The heterogeneous nature of the catalysis by La-USY was verified by filtration tests, and its stability was proved by X-ray diffraction and recycle experiments. Finally, the catalyst was used in the peroxidation of various olefinic compounds. Compared with conventional molybdate catalysts, La-USY is particularly useful for the selective peroxidation of allylic alcohol derivatives, with very little competitive epoxidation and no alcohol oxidation being observed.