《厦门大学学报（自然科学版）》

氨氮废水对环境的危害日益严重,催化湿式氧化技术能高效无害化处理氨氮废水,但现有催化剂工作条件苛刻.采用化学还原法制备2%Pd1%Ni/C双金属催化剂,并考察了其氨氮废水催化湿式氧化性能.结果表明:Pd和Ni的结合使得PdNi/C催化剂在更低贵金属用量的前提下,比相对应的单贵金属催化剂(Pd/C)具有更优的催化性能,尤其是低温催化性能.在每千克催化剂每小时处理约33 L模拟废水(氨氮的质量浓度为1 000 mg/L,pH=12)及反应压强为2 MPa处理3 h的条件下:在140 ℃时,2%Pd1%Ni/C催化剂能催化氧化脱除废水中99.0%的氨氮,且N2选择性为90.5%; 而3%Pd/C 和3%Ni/C催化剂的氨氮转化率仅分别为86.4%和50.6%; 即使在120 ℃的温和条件下,采用2%Pd1%Ni/C催化剂也能脱除80%以上的氨氮.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、CO程序升温还原(CO-TPR)对PdNi/C催化剂进行表征,结果表明Pd和Ni之间的协同作用调变了催化剂的亲氧性能,进而提高了氨氮转化率.

The pollution of wastewater containing ammonia becomes more and more serious.Ammonia can be efficiently removed by catalytic wet air oxidation(CWAO)technology.However,most of CWAO processes are operated at high pressures and temperatures,because the applied catalysts exhibited poor catalytic prefromance under mild conditions.In this study,PdNi/C bimetallic catalyst was prepared via a chemical reduction method and investigated for CWAO of ammonia to N2.It is found that the combining of Pd and Ni enables PdNi/C bimetallic catalyst to possess higher catalytic performance,especially at low temperatures,although it contains a lower Pd loading,compared with Pd/C.At 140 ℃,almost 100% ammonia can be removed by 2%Pd1%Ni/C bimetallic catalyst,while only 86.4% and 50.6% can be removed respectively with 3%Pd/C and 3%Ni/C,under the capacity around 33 L wastewater(ρ0NH3=1 000 mg/L,pH=12)per kilo catalyst per hour with the pressure of 2 MPa conduct for 3 h.Even at 120 ℃,more than 80% ammonia can be removed using 2%Pd 1%Ni/C.Moreover,the selectivity to N2 for 2%Pd1%Ni/C is higher than 90%.The characterization results of X-ray diffraction(XRD),CO temperature programmed reduction(CO-TPR)and X-ray photo-electron spectroscopy(XPS)indicate that the synergy between Pd and Ni modifies the redox properties and thus promotes the catalytic performance.

引言
1 实验部分
2 结果与讨论
3 结论

图1 实验装置简图<br/>Fig.1 Schematic diagram of experimental apparatus

图1 实验装置简图
Fig.1 Schematic diagram of experimental apparatus

表1 Pd和Ni协同作用对氨氮催化湿式氧化性能的影响<br/>Tab.1 Effect of synergy between Pd and Ni on the catalytic performance for catalytic wet air oxidation of ammonia %

表1 Pd和Ni协同作用对氨氮催化湿式氧化性能的影响
Tab.1 Effect of synergy between Pd and Ni on the catalytic performance for catalytic wet air oxidation of ammonia %

表2 Pd和Ni比例对催化氧化氨氮反应活性的影响<br/>Tab.2 Effect of Pd and Ni proportions on catalytic oxidation of ammonia%

表2 Pd和Ni比例对催化氧化氨氮反应活性的影响
Tab.2 Effect of Pd and Ni proportions on catalytic oxidation of ammonia%

图2 反应温度对2%Pd1%Ni/C和3%Pd/C催化活性的影响<br/>Fig.2 Effect of reaction temperature on catalytic activity of 2%Pd1%Ni/C and 3%Pd/C

图2 反应温度对2%Pd1%Ni/C和3%Pd/C催化活性的影响
Fig.2 Effect of reaction temperature on catalytic activity of 2%Pd1%Ni/C and 3%Pd/C

图3 3%Pd/C、2%Pd1%Ni/C和3%Ni/C的XRD谱图<br/>Fig.3 XRD patterns of 3%Pd/C,2%Pd1%Ni/C and 3%Ni/C

图3 3%Pd/C、2%Pd1%Ni/C和3%Ni/C的XRD谱图
Fig.3 XRD patterns of 3%Pd/C,2%Pd1%Ni/C and 3%Ni/C

图4 3%Ni/C、2%Pd1%Ni/C和3%Pd/C催化剂的CO-TPR结果<br/>Fig.4 CO-TPR profiles of 3%Ni/C,2%Pd1%Ni/C and 3%Pd/C catalysts

图4 3%Ni/C、2%Pd1%Ni/C和3%Pd/C催化剂的CO-TPR结果
Fig.4 CO-TPR profiles of 3%Ni/C,2%Pd1%Ni/C and 3%Pd/C catalysts

图5 3%Pd/C、3%Ni/C和2%Pd1%Ni/C的XPS表征结果<br/>Fig.5 XPS characterization results of 3%Pd/C,3%Ni/C and 2%Pd1%Ni/C

图5 3%Pd/C、3%Ni/C和2%Pd1%Ni/C的XPS表征结果
Fig.5 XPS characterization results of 3%Pd/C,3%Ni/C and 2%Pd1%Ni/C

[1] 吴悦颖,文宇立,刘伟江.“十二五”氨氮总量怎么减? [J].环境经济,2013(3):39-41.
[2] 付迎春,钱仁渊,金鸣林.催化湿式氧化法处理氨氮废水的研究 [J].煤炭转化,2004(2):72-75.
[3] KAEWPUANG-NGAM S,INAZU K,KOBAYASHI T,et al.Selective wet-air oxidation of diluted aqueous ammonia solutions over supported Ni catalysts [J].Water Research,2004,38(3):778-782.
[4] IMAMURA S,DOI A,ISHIDA S.Wet oxidation of ammonia catalyzed by cerium-based composite oxides [J].Industrial & Engineering Chemistry Product Research and Development,1985,24(1):75-80.
[5] QIN J Y,AIKA K.Catalytic wet air oxidation of ammonia over alumina supported metals [J].Applied Catalysis B:Environmental,1998,16(3):261-268.
[6] BARBIER J,JR,OLIVIERO L,RENARD B,et al.Catalytic wet air oxidation of ammonia over M/CeO2 ca-talysts in the treatment of nitrogen-containing pollutants [J].Catalysis Today,2002,75(1/2/3/4):29-34.
[7] CAO S L,CHEN G H,HU X J,et al.Catalytic wet air oxidation of wastewater containing ammonia and phenol over activated carbon supported Pt catalysts [J].Catalysis Today,2003,88(1/2):37-47.
[8] TAKAYAMA H,QIN J Y,INAZU K,et al.Hydrogen-treated active carbon supported palladium catalysts for wet air oxidation of ammonia [J].Chemistry Letters,1999,28(5):377-378.
[9] LEE D K,CHO J S,YOON W L.Catalytic wet oxidation of ammonia:why is N2 formed preferentially against NO3-? [J].Chemosphere,2005,61(4):573-578.
[10] LOUSTEAU C,BESSON M,DESCORME C.Catalytic wet air oxidation of ammonia over supported noble metals [J].Catalysis Today,2015,241:80-85.
[11] FU J L,YANG K X,MA C J,et al.Bimetallic Ru-Cu as a highly active,selective and stable catalyst for catalytic wet oxidation of aqueous ammonia to nitrogen [J].Applied Catalysis B:Environmental,2016,184:216-222.
[12] LIU Z,ZHANG X,HONG L.Physical and electrochemical characterizations of nanostructured Pd/C and PdNi/C catalysts for methanol oxidation [J].Electrochemistry Communications,2009,11(4):925-928.
[13] HOLADE Y,MORAIS C,ARRII-CLACENS S,et al.New preparation of PdNi/C and PdAg/C nanocatalysts for glycerol electrooxidation in alkaline medium[J].Electrocatalysis,2013,4(3):167-178.
[14] SHEN S Y,ZHAO T S,XU J B,et al.Synthesis of PdNi catalysts for the oxidation of ethanol in alkaline direct ethanol fuel cells [J].Journal of Power Sources,2010,195(4):1001-1006.
[15] JIN C C,SUN X J,CHEN Z D,et al.Electrocatalytic activity of PdNi/C catalysts for allyl alcohol oxidation in alkaline solution [J].Materials Chemistry and Physics,2012,135(2/3):433-437.
[16] 高艳伟,邓超,邬冰,等.PdNi/C催化剂的制备及对甲酸的电催化氧化 [J].化学工程师,2010,24(5):1-3.
[17] 沈阳市环境监测中心站.水质氨氮的测定纳氏试剂分光光度法:HJ 535—2009 [S].北京:中国环境科学出版社,2009.
[18] ZHU H Q,QIN Z F,SHAN W J,et al.Pd/CeO2-TiO2 catalyst for CO oxidation at low temperature:a TPR study with H2 and CO as reducing agents [J].Journal of Catalysis,2004,225(2):267-277.
[19] LEE D K.Mechanism and kinetics of the catalytic oxidation of aqueous ammonia to molecular nitrogen [J].Environmental Science and Technology,2003,37(24):5745-5749.
[20] WANG Z,HAMEED S,WEN Y,et al.The effect of weak acid anions on the selective catalytic wet air oxidation of aqueous ammonia to nitrogen [J].Scientific Reports,2017,7(1):3911.

备注

引言

1 实验部分

2 结果与讨论

3 结论

学报简介

备注

引言

1 实验部分

2 结果与讨论

3 结 论

学报简介

3 结论