纳米纤维支撑纳米二元金属的构建及饮用水催化脱硝应用研究

Source of drinking water being contaminated by nitrate is increasingly deteriorating, severely threatening human health. The reduction of nitrates to N2 by chemical catalysis has been regarded as the most promising method for denitrification in drinking water. It is a consensus that active metals and promoting metals should be combined together onto a suitable supports to form bimetallic catalysts for denitrification. Unfortunately, catalytic activity and N2 selectivity of the reported catalysts are generally low, and highly desired to be improved. Promoted by the unique advantages of electrospinning and our earlier-stage work, the catalyst-construction by electrospinning is expected to be a promising method for denitrification in drinking water. In the present project, we propose to assemble bimetalic nano-catalysts in/on nanofibers through electrospinning. By selection of species and proffered proportion, active metals, promoted metals and supporters are optimized paired. Meanwhile, diverse methods will be developed to control the micro and crystal structures of the metals and their supporters. We will construct and regulate the multiphase micro-interface and study it in reaction, and meanwhile, to evaluate the aqueous denitration performances and understand the reaction mechanism of the resulting catalyst, establishing the structure-activity relationship systematically. We are aiming to materialize the controllable fabrication and systematical study of the fiber-supported bimetallic nano-catalyst with excellent activity and ace N2 selectivity, ensuring drinking water safety and boosting the development of nanofiber technology.

饮用水源硝酸盐污染日趋严重，严重威胁人类健康。经化学催化把硝酸盐还原为氮气被认为是最具发展前景的饮用水脱硝方法。目前公认的催化剂结构是将主催化/助催化-二元金属负载到适当载体，但现有催化剂的活性和氮气选择性亟待提高。电纺丝的技术特点及我们的前期工作（反应快、且选择性超过绝大多数现有报道）说明采用电纺丝合成硝酸盐脱硝催化剂具有重要前景，但研究尚较空白。因此本项目提出在纳米纤维上构建纳米二元金属体系。一方面对活泼金属、助金属及载体的种类及比例进行优选，使三者形成优化配对；另一方面开发不同合成方法、优化反应条件，对金属及载体的微结构、晶态结构进行系统控制；同时构建并调控多相微界面，研究反应中的微界面机制；评估所得催化剂的水相脱硝效能，明晰反应机理及效能增强过程，系统建立构-效关系。最终实现高活性、高N2选择性的纤维基负载型纳米二元金属催化剂的可控制备与系统研究，促进饮用水安全及纳米纤维技术发展。

饮用水源硝酸盐污染日趋严重，威胁人类健康。经化学催化把硝酸盐还原为氮气被认为是最具发展前景的饮用水脱硝方法。目前公认的催化剂结构是将主催化/助催化-二元金属负载到适当载体，但现有催化剂的活性和氮气选择性亟待提高。电纺丝的技术特点及我们的工作基础（反应快、选择性好）说明采用电纺丝合成硝酸盐脱氮催化剂具有重要前景，但研究尚较空白。本项目以电纺丝纳米纤维为基础，从催化剂设计与制备，水处理硝酸盐催化还原性能测试与应用、构效关系与反应强化机制揭示三个层面开展深入研究。首先，采用静电纺丝技术，并结合原位负载、高温煅烧还原、溶液浸渍等手段，成功合成了氧化物半导体基Pd-Cu/TiO2，Pd-Cu/γ-Al2O3二元金属复合纳米催化剂，碳纳米纤维基Co-Mn/CNFs、Fe-Co/ CNFs、Pd-Cu /CNFs二元金属复合纳米催化剂，导电高分子基纳米金属/PPy微纳米纤维催化材料等，完成了催化剂材料的可控合成、结构表征，并实现了二元金属组成，微间距与表面电荷状态的精准控制。其次，面向水处理应用，基于硝酸盐去除率及N2选择性两参数，优化了催化剂的组成，同时探究了脱氮体系的最优反应条件，包括主催化金属与助催化金属的选择，催化剂载体的比选，反应温度、反应pH、催化剂投量、污染物浓度、水中干扰离子、还原剂H2分压等的确定，最终获得了高性能的催化体系，如采用Pd-Cu/TiO2纳米纤维，当地下水初始NO3--N浓度为30 mg/L时，反应30 min后，体系内副产物NH4+-N浓度仅为0.35mg/L（饮用水标准＜0.5mg/L），N2选择性约为96.5%，NO3--N和NH4+-N浓度都达到了饮用水卫生标准。机理方面，解析了二元金属分散度及双金属之间的微距离对反应活性影响机制，阐释了Pd表面电子结构对催化还原亚硝酸盐效能的影响和机制，获得了相应的控制副产物氨氮的规律和机理。发表SCI论文13篇，授权发明专利4项，获得黑龙江省技术发明二等奖1项，参编英文专著1部，培养3名博士研究生毕业，4名硕士研究生毕业。本项目有望为我国农村饮用水硝酸盐污染的控制和静电纺丝科技的发展提供重要数据。