A template carbonization strategy to synthesize ordered mesoporous silica microspheres with trapped sulfonated carbon nanoparticles for efficient catalysis.
A template carbonization strategy to synthesize ordered mesoporous silica microspheres with trapped sulfonated carbon nanoparticles for efficient catalysis.
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DOI：
10.1002/anie.201204719
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发表时间：
2012-10
影响因子：
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通讯作者：
Qin Yue;Minghong Wang;Jing Wei;Yonghui Deng;Tianyi Liu;R. Che;B. Tu;Dongyuan Zhao
中科院分区：
文献类型：
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作者：
Qin Yue;Minghong Wang;Jing Wei;Yonghui Deng;Tianyi Liu;R. Che;B. Tu;Dongyuan Zhao
有序介孔材料因其具有孔径和介孔结构可调、形貌可变、比表面积大、孔体积大等特点而备受关注。这些特性使它们成为催化、吸附和分离、化学传感和生物医学等应用的有希望的候选者。迄今为止，在介孔材料的合成方面已经取得了重大进展，特别是在使用表面活性剂或嵌段共聚物作为模板（结构导向剂）的软模板方法中，已经制备了具有可变孔结构，孔径大小和框架成分的大量有序介孔材料。除了探索合成方法和策略外，通过引入功能纳米材料或有机基团来设计具有实际应用价值的功能有序介孔材料已经付出了相当大的努力。例如，利用溶胶-凝胶化学方法，通过包覆功能纳米颗粒合成了许多功能介孔复合材料。此外，功能有机基团或纳米颗粒已被引入介孔，从而产生各种功能介孔材料，可用于药物输送，化学传感和催化。特别是在介孔中固定磺酸基团（-SO3H）引起了极大的研究兴趣，因为介孔材料可以提供大的可达表面积来支持高密度的酸性位点，从而作为高效的固体布朗斯特酸。与传统的均相酸催化剂（如H2SO4、AlCl3、BF3）相比，新型非均相酸催化剂对环境无害，并且可以很容易地从反应介质中回收，从而降低了化学品生产的能耗。为了在介孔二氧化硅材料的孔壁上引入磺酸基团，典型的方法是通过接枝或共缩合将含硫有机硅烷（例如SH， S）附着，然后用过氧化氢氧化。Van Rhijn等人首次报道了用共缩合或后改性的方法合成了SO3H官能团功能化的有序介孔二氧化硅。所制得的so3h功能化介孔二氧化硅具有良好的催化2-甲基呋喃与丙酮缩合的性能，对目标产物2,2-二（5-甲基呋喃）丙烷具有较高的转化率（85%）和选择性（96%）。相比之下，传统的微孔固体酸，如H-b和H-US-Y沸石，由于在狭窄的沸石孔中焦油低聚化合物的快速形成和吸附以及随后的催化剂失活，表现出较低的转化率（约60%）和选择性（约70%）。结果表明，SO3H基团在孔径较大的介孔二氧化硅中固定化更有利于催化。虽然通过接枝或缩聚可以很容易地合成具有SO3H官能团的介孔硅，但这些方法只允许使用有限数量的功能硅烷，以避免破坏有序的介孔结构或堵塞孔，导致低密度的磺酸基锚定在孔壁上。最近，Nakajima等人通过在SBA-15的孔隙中浸渍葡萄糖碳化，然后进行磺化处理，合成了含磺化碳的介孔二氧化硅SBA-15纤维。SO3H官能化介孔碳/二氧化硅在a-甲基苯乙烯二聚化反应中表现出良好的催化性能；然而，通过这种后浸渍，很难控制磺化碳的分布，避免孔隙堵塞。因此，开发新的方法和策略来合成功能化介孔非均相固体酸性催化剂具有重要的意义和意义。在此，我们展示了一种简单的模板碳化策略，通过溶剂蒸发诱导聚集组装（EIAA）方法合成有序的大孔介孔二氧化硅微球，其中磺化碳纳米颗粒被捕获在可访问的介孔内。在这种方法中,两亲性聚(环氧乙烷)-b-polystyrene (PEO-b-PS)和tetraethylorthorsilicate (teo)使用[*]问:悦,m . h . Wang j .魏教授黄懿慧邓博士,t . y . Liu教授博士r·c·格瓦拉b .涂博士教授,教授d . y .赵化学系博士,先进材料实验室智能药物输送的重点实验室,教育部复旦大学,上海200433(中国)电子邮件:yhdeng@fudan.edu.cn dyzhao@fudan.edu.cn主页:http://www.mesogroup.fudan.edu.cn/
Ordered mesoporous materials have attracted much attention since their discovery owing to their outstanding properties, such as tunable pore sizes and mesostructures, variable morphologies, high surface areas, and large pore volumes. These features make them promising candidates for applications including catalysis, adsorption and separation, chemical sensing, and biomedicine. To date, significant advances have been achieved in the synthesis of mesoporous materials, particularly in the soft templating approach using surfactants or block copolymers as the templates (structuredirecting agents), and enormous ordered mesoporous materials with variable pore structures, pore sizes, and framework compositions have been prepared. Apart from exploring the methods of synthesis and strategies, considerable efforts have been devoted to designing functional ordered mesoporous materials by introducing functional nanomaterials or organic groups for practical applications. For example, using sol–gel chemistry, many functional mesoporous composites have been synthesized by coating functional nanoparticles. Furthermore, functional organic groups or nanoparticles have been introduced into mesopores, resulting in various functional mesoporous materials that are useful in drug delivery, chemical sensing, and catalysis. Particularly the immobilization of sulfonic acid groups (-SO3H) in mesopores have aroused great research interest because the mesoporous materials can provide a large accessible surface area for supporting high density of acidic sites, thus serving as efficient solid Bronsted acids. Compared to traditional homogeneous acid catalysts (such as H2SO4, AlCl3, BF3), the novel heterogeneous catalysts are environmentally benign and can be readily recycled from reaction medium, thus reducing the energy consumption for the production of chemicals. To introduce sulfonic acid groups on the pore walls of mesoporous silica materials, typical methods involve the attachment of sulfur-containing organic silanes (for example SH, S S ) by post-grafting or co-condensation and subsequent oxidation with hydrogen peroxide. Van Rhijn et al. first reported the synthesis of ordered mesoporous silicas functionalized with SO3H groups using co-condensation or post-modification. The obtained SO3H-functionalized mesoporous silicas exhibited good performance in catalyzing the condensation of 2-methylfuran with acetone with high conversion (85%) and selectivity (96%) toward the target product 2,2-bis(5-methylfuryl)propane. By contrast, traditional microporous solid acids, such as H-b and H-US-Y zeolites, exhibited much lower conversion (ca. 60%) and selectivity (ca. 70%) owing to the undesired fast formation and adsorption of tarry oligomeric compounds in the narrow zeolite pores and subsequent catalyst deactivation. This result suggests that the immobilization of SO3H groups in mesoporous silicas with larger pore is more favorable for catalysis. Although mesoporous silicas functionalized with the SO3H groups can be easily synthesized by the post-grafting or cocondensation, these methods allow for only a limited amount of functional silanes to be used so as to avoid the damage of ordered mesostructure or pore blocking, resulting in a low density of sulfonic acid groups anchored in the pore walls. Recently, Nakajima et al. synthesized sulfonated carboncontaining mesoporous silica SBA-15 fibers by carbonization of the impregnated glucose in the pores of SBA-15, followed with a sulfonation treatment. The mesoporous carbon/silica functionalized with SO3H groups exhibited a good catalytic performance in the dimerization of a-methylstyrene; however, through this post impregnation, it is difficult to control the sulfonated carbon distribution and avoid pore blocking. Therefore, development of novel approaches and strategies to the synthesis of functionalized mesoporous heterogeneous solid acidic catalysts is of great importance and interest. Herein, we demonstrate a facile template carbonization strategy to synthesize ordered large-pore mesoporous silica microspheres with sulfonated carbon nanoparticles trapped inside the accessible mesopores through a solvent-evaporation-induced aggregating assembly (EIAA) approach. In this approach, amphiphilic poly(ethylene oxide)-b-polystyrene (PEO-b-PS) and tetraethylorthorsilicate (TEOS) were used [*] Q. Yue, M. H. Wang, J. Wei, Prof. Dr. Y. H. Deng, T. Y. Liu, Prof. Dr. R. C. Che, Prof. Dr. B. Tu, Prof. Dr. D. Y. Zhao Department of Chemistry, Advanced Materials Laboratory Key Laboratory of Smart Drug Delivery, Ministry of Education Fudan University, Shanghai 200433 (China) E-mail: yhdeng@fudan.edu.cn dyzhao@fudan.edu.cn Homepage: http://www.mesogroup.fudan.edu.cn/