Direct synthesis of Cr-MCM-48-like large pore mesoporous silica<br /> and its catalytic properties<br />
Journal Title: Science Paper Online - Year 2009, Vol 4, Issue 3
Abstract
Chromium substituted MCM-48-like large pore mesoporous silica with average pore size up to 10 nm was directly synthesized by using P123 (EO20PO70EO20) as template, n-butanol as assistant and chromium nitrate as chromium source. The Cr species were doped by simply adjusting the pH value of the synthesis system with ammonia from strong acid to nearly neutral after crystallization for 24 h. The Si/Cr ratios in the initial gel ranged from 10 to 80 and the actual weight percentage of Cr content was analyzed by ICP. X-ray diffraction pattern (XRD), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherm were employed to investigate the pore structure properties of these materials. The results indicate the pH adjusting method is an efficient way to incorporate large amount of chromium into the large pore Ia3d mesostructure. UV-vis and ESR spectra reveal that at lower Cr content (Si/Cr>30), only Cr (VI) and Cr(V) species exist in the mesoporous framework, and at higher Cr content, the Cr (III) species appeares. The catalysis ability of Cr-doped MCM-48-like large mesoporous silica for the oxidation of cyclohexane by hydroperoxide (H2O2) was also investigated and the conversion percent was high to 53%. The experiment using tert-butylhydroperoxide (TBHP) as oxidatnt got 86% cyclohexnone selectivity.
Authors and Affiliations
Lei WANG , Lingzhi WANG , Guodong CHEN , Jinlong ZHANG
Keywords
Related Articles
- EP ID EP139366
- DOI -
- Views 121
- Downloads 0
Effects of the morphology and structure of carbon spheres on the performance of PtRu/C catalysts for methanol oxidation
Three kinds of carbon materials synthesized by a hydrothermal method with different diameters and morphologies are selected as the support of PtRu catalysts for direct methanol fuel cells (DMFC). The structure and morpho...
蓝藻藻浆厌氧发酵技术研究现状及展望
蓝藻(Cyanobacteria)厌氧消化是一种具有广阔应用前景的蓝藻资源化技术，综述了蓝藻厌氧消化技术在国内外发展现状和存在问题。蓝藻厌氧发酵产甲烷大多数处于小试实验阶段，需要对其进行深入研究，以开发出适合蓝藻厌氧发酵产甲烷的工艺。...
Experimental study on viscosity properties of molten Zr50Cu50 alloy by rotating cylinder method
The dynamic viscosity of molten Zr50Cu50 alloy was measured by using rotating cylinder method and its variation with temperature was explored. The experimental results showed that viscosity of the molten alloy increases...
Cross-coupling control of multi-axis steering system based on sliding mode and PI method
Taking a construction vehicle which is independent driven by 8-axis steering system as the study prototype, the cross-coupling control strategy is discussed to improve the contour accuracy. The kinematic analysis of mult...
一种估计LFM信号参数的快速算法及其推广
提出一种估计线性调频(LFM)信号参数的快速算法，该算法利用计算信号的WVD(wigner-ville distribution)得到其时间－频率值的二维分布，进而通过计算不同的时间采样点所对应的频率值来获取LFM信号的调频斜率以及初始频率的估计。算法的实现...