非热等离子体强化尿素-SCR脱除NO_x
|
摘要
针对低温条件下尿素-SCR存在的尿素分解不完全以及脱硝效率低的问题,利用介质阻挡放电产生非热等离子体,并将其与同时具有催化尿素分解和催化NO_x还原活性的MnO_x/Al_2O_3催化剂相结合,考察了非热等离子体对于低温(100℃)下尿素催化分解制氨以及NH_3-SCR和尿素-SCR脱除NO_x的强化作用。结果表明:仅有催化作用时100℃下尿素难以分解,NH_3-SCR也仅能脱除23. 0%的NO_x。在催化床层内施加较低放电功率(约10 W)的非热等离子体既可促使尿素在低温下高效分解制氨,又可显著强化NH_3-SCR对于NO的脱除,并最终在MnO_x/Al_2O_3催化剂表面实现尿素-SCR高效脱除NO。
In order to solve the problems such as incomplete urea decomposition and low denitrification efficiency existing in urea-SCR at low temperatures,non-thermal plasma( NTP) was generated by dielectric barrier discharge and combined with MnO_x/Al_2 O_3 catalyst for both urea decomposition and NO_x reduction in this study. The effects of NTP on urea decomposition and NO_x removal by NH_3-SCR and urea-SCR were separately investigated at low temperature( 100 ℃). Experimental results showed that urea could not be effectively decomposed by catalysis under 100 ℃,and NO_x removal efficiency could only reach23. 0% by NH_3-SCR. Generation of NTP in the catalyst bed at low discharge power( ～ 10 W) could achieve effective production of ammonia from urea decomposition,and significantly promote the removal of NO by NH_3-SCR and eventually obtain efficient removal of NO by urea-SCR on the surface of MnO_x/Al_2 O_3 catalyst.
In order to solve the problems such as incomplete urea decomposition and low denitrification efficiency existing in urea-SCR at low temperatures,non-thermal plasma( NTP) was generated by dielectric barrier discharge and combined with MnO_x/Al_2 O_3 catalyst for both urea decomposition and NO_x reduction in this study. The effects of NTP on urea decomposition and NO_x removal by NH_3-SCR and urea-SCR were separately investigated at low temperature( 100 ℃). Experimental results showed that urea could not be effectively decomposed by catalysis under 100 ℃,and NO_x removal efficiency could only reach23. 0% by NH_3-SCR. Generation of NTP in the catalyst bed at low discharge power( ～ 10 W) could achieve effective production of ammonia from urea decomposition,and significantly promote the removal of NO by NH_3-SCR and eventually obtain efficient removal of NO by urea-SCR on the surface of MnO_x/Al_2 O_3 catalyst.
引文
[1]贺泓,翁端,资新运.柴油车尾气排放污染控制技术综述[J].环境科学,2007,28(6):1169-1177.
[2] Hussain J,Palaniradja K,Algumurthi N,et al. Diesel engine emissions and after treatment techniques-a review[J]. Journal of Engineering Research and Studies,2012,3(2):34-44.
[3] Bernhard A M,Peitz D,Elsener M,et al. Catalytic urea hydrolysis in the selective catalytic reduction of NOx:catalyst screening and kinetics on anatase Ti O2and Zr O2[J]. Catalysis Science&Technology,2013,3(4):942-951.
[4] Piazzesi G,Nicosia D,Devadas M,et al. Investigation of HNCO adsorption and hydrolysis on Fe-ZSM5[J]. Catalysis Letters,2007,115(1/2):33-39.
[5] Cheng X,Bi X. A review of recent advances in selective catalytic NOxreduction reactor technologies[J]. Particuology,2014,16:1-18.
[6] Guan B,Zhan R,Lin H,et al. Review of state of the art technologies of selective catalytic reduction of NOxfrom diesel engine exhaust[J]. Applied Thermal Engineering, 2014, 66(1/2):395-414.
[7] Wang T,Wan Z T,Yang X C et al. Promotional effect of iron modification on the catalytic properties of Mn-Fe/ZSM-5 catalysts in the fast SCR reaction[J]. Fuel Processing Technology,2018,169:112-121.
[8] Yang W J,Chen Z C,Zhou J H,et al. Catalytic performance of zeolites on urea thermolysis and isocyanic acid hydrolysis[J].Industrial&Engineering Chemistry Research,2011,50(13):7990-7997.
[9] Li G H,Jones C A,Grassian V H,et al. Selective catalytic reduction of NO2with urea in nanocrystalline Na Y zeolite[J].Journal of Catalysis,2005,234(2):401-413.
[10] Johar J S. An experimental investigation of the urea-water decomposition and selective catalytic reduction(SCR)of nitric oxides with urea using V2O5-WO3-Ti O2catalyst[J]. Applied Energy,2005,158(21):631-642.
[11]管斌,林赫,程琪,等.低温等离子体协同NH3-SCR去除柴油机NOx研究[J].工程热物理学报,2010,31(10):1767-1771.
[12]程琪,管斌,林赫,等.等离子体辅助NH3-SCR去除柴油机NOx的试验研究[J].车用发动机,2010(1):33-36.
[13] Yim S D,Kim S J,Baik J H,et al. Decomposition of urea into NH3for the SCR process[J]. Industrial&Engineering Chemistry Research,2004,43(16):4856-4863.
[14] Mizuno A. Generation of non-thermal plasma combined with catalysts and their application in environmental technology[J].Catalysis Today,2013,211:2-8.
[15] Fan X,Zhu T L,Wang M Y,et al. Removal of low-concentration BTX in air using a combined plasma catalysis system[J].Chemosphere,2009,75(10):1301-1306.
[16] Fan X,Zhu T L,Sun Y F,et al. The roles of various plasma species in the plasma and plasma-catalytic removal of lowconcentration formaldehyde in air[J]. Journal of Hazardous Materials,2011,196:380-385.
[17] Van Durme J,Dewulf J,Leys C,et al. Combining non-thermal plasma with heterogeneous catalysis in waste gas treatment:a review[J]. Applied Catalysis B:Environmental,2008,78(3/4):324-333.
[18] Czekaj I,Krocher O. Decomposition of urea in the SCR process:combination of DFT calculations and experimental results on the catalytic hydrolysis of isocyanic acid on Ti O2and Al2O3[J].Topics in Catalysis,2009,52:1740-1745.
[19] Miessner H,Francke K P,Rudolph R,et al. NOxremoval in excess oxygen by plasma-enhanced selective catalytic reduction[J].Catalysis Today,2002,75(1/2/3/4):325-330.
[20] Guan B,Lin H,Cheng Q,et al. Removal of NOxwith selective catalytic reduction based on nonthermal plasma preoxidation[J].Industrial&Engineering Chemistry Research,2011,50(9):5401-5413.
[2] Hussain J,Palaniradja K,Algumurthi N,et al. Diesel engine emissions and after treatment techniques-a review[J]. Journal of Engineering Research and Studies,2012,3(2):34-44.
[3] Bernhard A M,Peitz D,Elsener M,et al. Catalytic urea hydrolysis in the selective catalytic reduction of NOx:catalyst screening and kinetics on anatase Ti O2and Zr O2[J]. Catalysis Science&Technology,2013,3(4):942-951.
[4] Piazzesi G,Nicosia D,Devadas M,et al. Investigation of HNCO adsorption and hydrolysis on Fe-ZSM5[J]. Catalysis Letters,2007,115(1/2):33-39.
[5] Cheng X,Bi X. A review of recent advances in selective catalytic NOxreduction reactor technologies[J]. Particuology,2014,16:1-18.
[6] Guan B,Zhan R,Lin H,et al. Review of state of the art technologies of selective catalytic reduction of NOxfrom diesel engine exhaust[J]. Applied Thermal Engineering, 2014, 66(1/2):395-414.
[7] Wang T,Wan Z T,Yang X C et al. Promotional effect of iron modification on the catalytic properties of Mn-Fe/ZSM-5 catalysts in the fast SCR reaction[J]. Fuel Processing Technology,2018,169:112-121.
[8] Yang W J,Chen Z C,Zhou J H,et al. Catalytic performance of zeolites on urea thermolysis and isocyanic acid hydrolysis[J].Industrial&Engineering Chemistry Research,2011,50(13):7990-7997.
[9] Li G H,Jones C A,Grassian V H,et al. Selective catalytic reduction of NO2with urea in nanocrystalline Na Y zeolite[J].Journal of Catalysis,2005,234(2):401-413.
[10] Johar J S. An experimental investigation of the urea-water decomposition and selective catalytic reduction(SCR)of nitric oxides with urea using V2O5-WO3-Ti O2catalyst[J]. Applied Energy,2005,158(21):631-642.
[11]管斌,林赫,程琪,等.低温等离子体协同NH3-SCR去除柴油机NOx研究[J].工程热物理学报,2010,31(10):1767-1771.
[12]程琪,管斌,林赫,等.等离子体辅助NH3-SCR去除柴油机NOx的试验研究[J].车用发动机,2010(1):33-36.
[13] Yim S D,Kim S J,Baik J H,et al. Decomposition of urea into NH3for the SCR process[J]. Industrial&Engineering Chemistry Research,2004,43(16):4856-4863.
[14] Mizuno A. Generation of non-thermal plasma combined with catalysts and their application in environmental technology[J].Catalysis Today,2013,211:2-8.
[15] Fan X,Zhu T L,Wang M Y,et al. Removal of low-concentration BTX in air using a combined plasma catalysis system[J].Chemosphere,2009,75(10):1301-1306.
[16] Fan X,Zhu T L,Sun Y F,et al. The roles of various plasma species in the plasma and plasma-catalytic removal of lowconcentration formaldehyde in air[J]. Journal of Hazardous Materials,2011,196:380-385.
[17] Van Durme J,Dewulf J,Leys C,et al. Combining non-thermal plasma with heterogeneous catalysis in waste gas treatment:a review[J]. Applied Catalysis B:Environmental,2008,78(3/4):324-333.
[18] Czekaj I,Krocher O. Decomposition of urea in the SCR process:combination of DFT calculations and experimental results on the catalytic hydrolysis of isocyanic acid on Ti O2and Al2O3[J].Topics in Catalysis,2009,52:1740-1745.
[19] Miessner H,Francke K P,Rudolph R,et al. NOxremoval in excess oxygen by plasma-enhanced selective catalytic reduction[J].Catalysis Today,2002,75(1/2/3/4):325-330.
[20] Guan B,Lin H,Cheng Q,et al. Removal of NOxwith selective catalytic reduction based on nonthermal plasma preoxidation[J].Industrial&Engineering Chemistry Research,2011,50(9):5401-5413.