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工程科学与技术:2019,51(6):44-53
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NCNTs/PSSF微纤复合催化剂的制备及在苯酚降解中的应用
(华南理工大学 化学与化工学院, 广东 广州 510640)
Synthesis of NCNTs/PSSF Microfibrous Composite Catalyst for the Degradation of Phenol
(College of Chemistry and Chemical Eng., South China Univ. of Technol., Guangzhou 510640, China)
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投稿时间:2019-07-12    修订日期:2019-09-10
中文摘要: 由于粉末催化剂在连续流动的催化体系中存在压降较高、易堵塞等局限,同时金属负载型催化剂易出现活性组分流失的问题,本文探究了高空隙率的整体式复合碳材料在含酚废水连续化处理中的应用。首先以廉价易得的三聚氰胺为单一的氮源和碳源,采用化学气相沉积法(chemical vapor deposition, CVD)在纸状烧结不锈钢微纤材料(paper-like sintered stainless steel fibers, PSSF)表面生长氮掺杂碳纳米管(nitrogen-doped carbon nanotubes, NCNTs)合成整体式的NCNTs/PSSF复合催化剂。采用SEM、TG热重分析、比表面积及孔径分析等技术考察不同合成温度、载气流量及三聚氰胺用量对NCNTs/PSSF复合催化剂的微观形貌及结构的影响,最后在最佳催化剂合成条件下进行固定床反应器上复合催化剂湿式催化氧化降解苯酚的性能测试。合成条件探究结果表明,复合催化剂具有发达3维网状结构,且纤维表面环绕包裹着一层碳纳米管。随合成温度上升纤维表面NCNTs缺陷程度下降,有序度提高,当温度升至1 000 ℃时发生明显的石墨化转变;随载气流量上升,纤维表面NCNTs产量下降,但比表面积及总孔体积有所增加,缺陷程度上升;随三聚氰胺用量增加,纤维表面NCNTs产量及比表面积上升,但缺陷程度几乎不变。最优合成条件下复合催化剂的比表面积可达14.50 m2/g,相比PSSF载体增加近45倍,TEM分析表明合成的NCNTs具有典型的褶皱结构,氮原子掺杂量达4%。湿式催化氧化苯酚的结果表明,在2 cm催化剂床层高度(约含有0.5 g NCNTs),2 mL/min流量及80 ℃条件下反应9 h,复合催化剂可保持99%的H2O2转化率,80%的苯酚转化率及45%的TOC转化率,Fe3+浸出浓度仅为1.5 mg/L。稳定性测试结果表明,反应100 h复合催化剂仍能保持80%以上的苯酚转化率,且Fe3+浸出浓度低于5 mg/L。
Abstract:Due to the limitations of powdered catalysts in continuous catalytic system, such as high pressure drop, easy blocking and the loss of active components, monolithic carbonaceous composite catalyst with high voidage was employed for phenol degradation in fixed bed reactor. Firstly, monolithic NCNTs/PSSF microfibrous composite catalyst was synthesized by chemical vapor deposition (CVD) method using melamine as the sole carbon and nitrogen source, and effects of temperature, flow rate of carrier gas and the amount of melamine on the morphology and structure of catalyst were investigated. Then catalyst synthesized under optimized conditions was applied for catalytic wet peroxide oxidation of phenol in a fixed bed reactor. Characterization results indicated that the catalyst exhibited a three-dimensional network structure and stainless steel fibers were wrapped with NCNTs. The quality and yield of NCNTs increased with the increase of temperature, while morphology transition could be observed at 1 000 ℃. With the increase of carrier gas flow rate, the yield and quality of NCNTs decreased while the specific surface areas and total pore volume increased.With the increase of the amount of melamine, the yield of NCNTs increased and the quality remained nearly unchanged. The specific surface areas of catalyst synthesized under optimized conditions was 14.50 m2/g, about 45 times larger than that of the bare PSSF support, and TEM images showed that NCNTs with a nitrogen-doping level about 4% exhibited distinct inter-linked corrugated morphology and highly wrinkled nanotube walls. CWPO of phenol under conditions of 2 cm of catalyst bed height (contained only about 0.5 g NCNTs), 2 mL/min of feed flow rate and temperature of 80 ℃ showed that 99% of H2O2 conversion could be achieved, and phenol and TOC conversions could reach 80% and 45%, respectively, after 9 h continuous reaction. Moreover, only few Fe3+ leaching concentration (1.5 mg/L) was detected. Long term catalytic tests further indicated that high phenol conversion over 80% could still be achieved by using the catalyst over 100 h, and Fe3+ leaching concentration was detected lower than 5 mg/L.
文章编号:201900702     中图分类号:    文献标志码:
基金项目:国家自然科学基金项目(21776106)
作者简介:黄浩鑫(1995-),男,硕士生.研究方向:废水处理.E-mail:h.hx01@mail.scut.edu.cn
引用文本:
黄浩鑫,张会平,鄢瑛.NCNTs/PSSF微纤复合催化剂的制备及在苯酚降解中的应用[J].工程科学与技术,2019,51(6):44-53.
HUANG Haoxin,ZHANG Huiping,YAN Ying.Synthesis of NCNTs/PSSF Microfibrous Composite Catalyst for the Degradation of Phenol[J].Advanced Engineering Sciences,2019,51(6):44-53.