Performance test mn and mn ce mixed oxide as low temperature catalysts in nh3 scr process for nox removal from stationary sources

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY PHIMNAPHA SYHABOUTH PERFORMANCE TEST: MN AND MN-CE MIXED OXIDE AS LOW TEMPERATURE CATALYSTS IN NH3-SCR PROCESS FOR NOX REMOVAL FROM STATIONARY SOURCES BACHELOR THESIS Study mode : Full-time Major : Environmental Science and Management Faculty : International Programs Office Batch : K45 AEP (2013-2017) Thai Nguyen, 17/11/2017 DOCUMENTATION PAGE WITH ABSTRACT Thai Nguyen University of Agriculture and Forestry Degree program Bachelor of Environmental Science and Management Student’s name Phimnapha Syhabouth Student ID DTN1353110557 Thesis Title Performance Test: Mn And Mn-Ce Mixed Oxide As Low Temperature Catalysts in NH3-SCR Process For NOx Removal From Stationary Sources Supervisors Hsun Ling Bai, Ph.D Nguyen Thi Thu Huong, MSc Abstract: This thesis describes a laboratory-scale experiment to evaluate the performance of catalysts in conversing NOx from stationary sources Mn oxide/TiO2 and MnCe/TiO2 mixed oxide catalysts, denoted as Mn20/TiO2, Mn20Ce10/TiO2, and Mn20Ce20/TiO2 were used as samples The process of the synthesis, preparation, and performance test of those sample catalysts were recorded and described in detail Moreover, the experimental result shows that at operating temperature at 150°C, concentration of NH3 and NO at 200ppm, and hourly volumetric feed gas flow rate/reaction volume (GHSV) at 20,000 h-1, the NO concentration of the outflow gas from all three experiments with three kinds of catalysts were above 80% However, Mn-Ce catalysts performed better than only Mn-catalyst Page Keyword SCR, low temperature catalyst, Mn/TiO2, Mn– Ce/TiO2, NOx Number of page 40 Date of submission 10/10/2017 Page ACKNOWLEDGEMENT I would like to express my heartfelt gratitude to my supervisors Firstly, to Prof Hsun Ling Bai, thank you for accepting me as an intern student to conduct experiments in the laboratory and for all suggestions and advice of my experimental work Secondly, thank you MSc Nguyen Thi Thu Huong for taking time from your busy schedule to correct my writing and also for your continuously kind support and guidance not only for my thesis but throughout my final year of college A special thank goes to AEP program for offering us advanced education With the diversity of teaching methods, professional teachers, cultural environments provided by AEP, it allows me to graduate as a quality citizen Moreover, thank you both Thai Nguyen University of Agriculture and Forestry and National Chiao Tung University for encouraging us to conduct a graduation project in Taiwan It was a last but one of the most meaningful time of my college duration Furthermore, this thesis would not successfully been conducted without my advisor, Lin Yun-Ting, a good friend who was with me in every laboratory sessions and offer me helps since the arrival until the departure from Taiwan Lastly, to my parents, sister and my big family, thank you for believing in me, the encouragement and also financial support throughout my Page life I own this success to all of you This thesis is a product of supports from all of you that I have mentioned above Even though, the time in doing this thesis is limited, so that I only obtained small amount of data, however, with my writing, I wish this thesis could be used as a reference for the beginner in NH3-SCR field Phimnapha Syhabouth Page TABLE OF CONTENT ACKNOWLEDGEMENT TABLE OF CONTENT LIST OF ABBRIVIATION LIST OF TABLE PART 1: INTRODUCTION 10 Research’s objectives 11 Research’s questions 12 PART 2: LITERATURE REVIEW 13 2.1 Nitrogen oxides (NOx) 13 2.1.1 Definition 13 2.1.2 Sources of NOx 13 2.1.3 Adverse Impacts of NOx 14 2.2 Selective Catalytic Reduction (SCR) 14 2.2.1 Process Description 15 2.3 Catalyst 15 2.3.1 Mn/TiO2 16 2.3.2 MnO2-CeO2 Catalysts 17 Page PART METHODOLOGY 18 3.1 Overview of Research Design 18 3.2 Materials and Equipment 19 3.2.1 For Catalyst Synthesis 19 3.2.2 For Catalyst Preparation 21 3.2.3 For Catalyst Performance Test 22 3.3 Methodology 23 3.3.1 Catalyst Synthesis 23 3.3.2 Catalyst Preparation 24 3.3.3 Performance Test 25 PART 4: RESULTS AND DISCUSSION 28 4.1 Result 28 4.1.1 The Synthesis of the Catalyst 28 4.1.2 The preparation of catalyst 29 4.1.3 Performance test of the catalysts 29 4.2 Discussion 32 PART 5: CONCLUSION 35 REFERENCE 36 Page LIST OF ABBRIVIATION SCR - Selective Catalytic Reduction GHSV - Hourly volumetric feed gas flow rate/reaction volume ppm - parts per million ccm - Cubic Centimeter DI - Deionized Water Page LIST OF TABLE Table Methodology to Answer Research Questions 19 Table Materials for Catalyst Synthesis 20 Table The Amount of Precursor in Each Catalyst 23 Page LIST OF FIGURE Figure The magnetic stirrer: it is for stirring catalysts precursers in a synthesis process 21 Figure The pressure plumber to press catalyst powder into a hard piece 22 Figure The Catalyst Synthesis Process 24 Figure The Catalyst Preparation Process 25 Figure SCR system for catalyst’s performance test 26 Figure The Catalytic Reactor 27 Figure The synthesized catalyst (after calcination), from left to right (Mn20Ce20/TiO2, Mn20Ce10/TiO2, Mn20/TiO2) 28 Figure The Transformation of Catalyst from Powder into Pellet Type 29 Figure The stability of Mn20/TiO2 catalyst in NOx conversion 30 Figure 10 The stability of Mn20 Ce10/TiO2 catalyst in NOx conversion 30 Figure 11 The stability of Mn20 Ce20/TiO2 catalyst in NOx conversion 31 Figure 12 The Average NO conversion (%) of each catalyst 31 Page Figure SCR system for catalyst’s performance test The mechanism of the reaction of catalyst is demonstrated in figure Firstly, ammonia, nitric oxide, and air were injected in to the mixing tube The mixing gas flows to the heated reactor and through the catalyst’s bed tube In this stage, the catalyst accelerates NH3 to react with NO to form N2 and water The outflow is the treated gas The NO conversion rate was detected in the outflow gas every 30 minute for hours By using NO detector, the NO conversion rate can be detected in the outflow for further analysis Page 26 Figure The Catalytic Reactor Page 27 PART 4: RESULTS AND DISCUSSION 4.1 Result 4.1.1 The Synthesis of the Catalyst All three catalysts with different loading of precursors were successfully synthesized by co-precipitation method After being filtered and washed by 2000ml distilled water, the catalyst was left dried overnight in the oven, followed by the calcination for hours Figure The synthesized catalyst (after calcination), from left to right (Mn20Ce20/TiO2, Mn20Ce10/TiO2, Mn20/TiO2) Final pH value was recorded The pH value of the aqueous catalyst is shown below: Page 28  Mn20/TiO2: pH= 10.47  Mn20Ce10/TiO2: pH= 9.96  Mn20Ce20/TiO2: pH= 10.02 4.1.2 The preparation of catalyst In this study, all three catalysts were prepared by the same method as described in the methodology part earlier The result yielded the catalyst into the pellet type Figure The Transformation of Catalyst from Powder into Pellet Type 4.1.3 Performance test of the catalysts All three catalysts were tested in a flow gas reactor for hours To evaluate the stability of each catalyst, the conversion rate was recorded in every 30 minute (as shown in the figure 9) Page 29 100 83.58 82.59 81.59 82.09 NO conversion (%) 80 60 40 Mn20 20 0 0.5 1.5 2.5 Time Figure the stability of Mn20/TiO2 catalyst in NOx conversion 100 91.09 89.60 89.11 88.61 NO conversion (%) 80 60 40 Mn20Ce10 20 0 0.5 1.5 2.5 Time Figure 10 The stability of Mn20 Ce10/TiO2 catalyst in NOx conversion Page 30 100 84.39 85.37 84.88 84.88 NO conversion (%) 80 60 40 Mn20Ce20 20 0 0.5 1.5 2.5 Time Figure 11 The stability of Mn20 Ce20/TiO2 catalyst in NOx conversion After two hours in a flow reactor machine, Mn20Ce10/TiO2 accelerated 89.55% of NO conversion rate While Mn20/TiO2 and Mn20Ce20/TiO2 can only convert 82.46% and 84.87% of NO, respectively (as shown in figure 12) 100 90 80 89.55 82.46 84.88 70 60 NO 50 conversion(%) 40 Series 30 20 10 Mn20/Tio2 Mn20 Ce10/Tio2 Mn20 Ce20/TiO2 Catalysts Figure 12 The Average NO conversion (%) of each catalyst Page 31 The bar chart of figure 12 suggests that Mn20Ce10/TiO2 performed best in converting NO with the conversion rate of 89.55% While Mn20/TiO2 and Mn20Ce20/TiO2 has lower potential with only 82.46% and 84.88% of NO conversion rate, respectively 4.2 Discussion The objectives of the research are to record the synthesis process of the low temperature catalyst and compare three catalysts’ performances, which are Mn20/TiO2, Mn20Ce10/TiO2, and Mn20Ce20/TiO2 The synthesis of the catalysts was successful The morphology of every catalysts showed no difference As can be seen from figure 7, after being calcinated, the catalyst just turned into a darker color In fact, catalysts can be characterized to study BET surface area, pore volume XRD pattern Characterization is used to suggest characteristics of each catalyst, thus factors affecting their performance can be obtained Nevertheless, due to the lack of time and resources, the characteristic of these catalysts has not been studied Only the pH of each aqueous catalyst precursor was documented Initially, the pH of all catalysts was expected to be as close as 10 to avoid bias However, as can be seen above, Mn20/TiO2 has pH of 10.47 which is quite different from those of others Even though it is a small different in value, it is important to note it for further analysis of the catalyst It is because catalyst activity was achieved when the Mn4+ species was predominant on the catalyst surface, and that the Mn valence state was dependent on the pH of the TiO2 aqueous slurry during the catalyst preparation process (Kim, Hong, 2012) Page 32 After the synthesis, the catalysts were not ready to be used in the SCR process It was still need to be transformed into a pellet type By repeating the same procedure, three series of catalysts had similar size when in the form of pellet type Therefore, it is assumed that this thesis has no bias from catalyst’s surface area In term of the catalysts’ performances, as can be seen from the graph 7, 8, 9, all three catalysts have the conversion rate above 80%, and performed stably during the whole process Mn20/TiO2 with the operating condition as: temperature=150°C, ratio of NH3=NO=200 ppm, GHSV=20,000 h-1, showed 82.46% of NOx conversion rate The result agrees with Pena et al.’s experiment in 2004, in which NOx conversion rate of Mn20/TiO2 was 80% Noted that Pena tested Mn20/TiO2 at 100°C, 400 ppm of NH3 and NO, GHSV=50,000 h-1, and with 2% of oxygen presence According to the research, the addition of cerium in the catalyst enhanced the catalyst’s performance It was discovered that Mn-Ce with the ration of Mn(Mn+Ce)=0.3, operating at 120ºC, and at a high space velocity of 42,000h–1 could perform nearly 100% of NO conversion (Qi and Yang, 2003) The result of this research is complied with Qi and Yang’s experiment that cerium contribute to the betterment of NO conversion although with lower conversion rate, which Mn20Ce10/TiO2 and Mn20Ce20/TiO2 yielded NOx conversion of 89.55% and 84.88%, respectively By adding cerium more (as in Mn20Ce20/TiO2), conversion rate was decreased The reasons behind this are not yet known because the characteristic of the catalysts has not been done, due to the lack of resources Page 33 It is also important to note that although the data revealed that this type of catalyst performed well at this temperature, and operating factors; however, the operating condition were different among difference literature, hence it is hard to understand which type of catalyst performed better The comparison of catalysts from difference literature could be made only with each operating conditions shown Nevertheless, based on this experiment, we can obtain that among all three catalysts, tested under these conditions: T=120°C, NH3=NO=200 ppm, 20,000-h of GHSV, Mn20Ce10/TiO2 performed best, followed by Mn20Ce20/TiO2 and Mn20/TiO2 Page 34 PART 5: CONCLUSION The synthesis and preparation of catalyst were successful All three types of catalysts were used in the experiments According to the data from the experiment, three catalysts, namely Mn20/TiO2, Mn20Ce10/TiO2, Mn20Ce20/TiO2 were efficient to reduce NOx from stationary sources, which the conversion rate were 82.46%, 89.55%, 84.88% respectively To be specific, with the aid of Cerium, catalysts tended to perform better Mn20Ce10TiO2, which 10% of Cerium was added, performed best among three catalysts However, by adding more Cerium (20%) as in Mn20Ce20TiO2, the performance of catalyst was likely to decline It can be concluded that, all two main objectives were obtained and also three research question has been answered by the experiments However, due to the time constraint, the research could only test each catalyst in one replication, which means the result could only be used as a reference for a further study but not in real life usage Three tested catalysts should be analyzed for reasons 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Mixed Oxide As Low Temperature Catalysts in NH3- SCR Process For NOx Removal From Stationary Sources Supervisors Hsun Ling Bai, Ph.D Nguyen Thi Thu Huong, MSc Abstract: This thesis describes a laboratory-scale...  To describe the synthesis, preparation and performance test of low temperature catalysts (Mn2 0/TiO2, Mn2 0Ce1 0/TiO2, Mn2 0Ce2 0/TiO2)  To compare the efficiency of three catalysts for NOx reduction