载银海藻酸钙复合材料制备及其催化性能研究

发布时间：2018-06-03 15:02

本文选题：银纳米颗粒 + 海藻酸钠　；参考：《大连工业大学》2015年硕士论文

【摘要】：金属纳米材料因其独特的物理化学性质,广泛应用于光学器件,电子工业,催化和生物科技等领域。为了避免金属纳米颗粒的团聚,通常将纳米颗粒固定在各种载体上,如实心和空心球表面,多孔硅基材料和三维立体结构的水凝胶等。海藻酸钠作为一种多糖类的生物水凝胶,容易与二价金属阳离子发生交联,转化成具有三维立体网状结构的水凝胶。由于海藻酸盐在大多数有机溶液中能够稳定存在,并且具有大量的官能团,因此海藻酸盐的水凝胶可以作为金属纳米颗粒的载体,应用于多相催化反应。为了提高银纳米颗粒的分散均匀性和有效解决团聚问题,本论文报道了一种简单且环保节能的方法制备载银海藻酸钙(Ag/CA)凝胶颗粒,将该材料应用于对硝基苯酚的还原反应,表现出良好的催化活性,但此类催化剂存在循环使用性不理想的问题。通过对循环使用前后的Ag/CA凝胶颗粒进行表征和分析,发现循环使用性差的原因是Ca2+与溶液中的Na+发生交换,破坏了水凝胶的内部结构,导致银纳米粒子流失。基于上述问题,本研究课题选择戊二醛作为交联剂,对Ag/CA凝胶颗粒进行改性,得到了戊二醛交联的载银海藻酸钙(Ag/CA@GTA)凝胶颗粒,将其应用于对硝基苯酚的还原反应,发现Ag/CA@GTA凝胶颗粒表现出较好的循环使用性,10次循环反应后,仍然保持较高的反应转化率(97%)。本论文所提出的催化剂制备方式是一种通用的方法,采用这种方法可以担载其他的具有催化活性的金属纳米颗粒,用于不同的多相催化反应,因此,具有广阔的应用前景。
[Abstract]:Metal nanomaterials are widely used in optical devices, electronics, catalysis and biotechnology due to their unique physical and chemical properties. In order to avoid the agglomeration of metal nanoparticles, nanoparticles are usually immobilized on various carriers, such as truthful cores and hollow spheres, porous silicon based materials and three-dimensional hydrogels. Sodium alginate, as a polycarbohydrate biogel, is easily crosslinked with divalent metal cations and transformed into hydrogels with three-dimensional net structure. Because alginate can exist stably in most organic solutions and has a large number of functional groups, the hydrogel of alginate can be used as the carrier of metal nanoparticles for heterogeneous catalytic reactions. In order to improve the dispersion uniformity of silver nanoparticles and to solve the agglomeration problem effectively, a simple and environmentally friendly and energy saving method for preparing calcium alginate loaded Ag / CA gel particles was reported in this paper. The material was applied to the reduction of p-nitrophenol. The catalyst showed good catalytic activity, but its recycle performance was not ideal. Through the characterization and analysis of Ag/CA gel particles before and after recycling, it was found that the poor recycling performance was due to the exchange of Ca2 with Na in solution, which destroyed the internal structure of hydrogel and resulted in the loss of silver nanoparticles. Based on the above problems, glutaraldehyde was selected as the crosslinking agent to modify the Ag/CA gel particles, and the glutaraldehyde cross-linked calcium alginate / CAGTA-containing gel particles were obtained and applied to the reduction of p-nitrophenol. It was found that the Ag/CA@GTA gel particles showed good recycling performance after 10 cycles, and still maintained a high conversion rate of 97%. The catalyst preparation method proposed in this paper is a general method. This method can support other metal nanoparticles with catalytic activity and be used in different heterogeneous catalytic reactions, so it has a broad application prospect.
【学位授予单位】：大连工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33;O643.36

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