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Development of the Next Generation Ammonia DeNOx Catalyst

下一代氨脱硝催化剂的开发

基本信息

批准号：
10558093
负责人：
SASAOKA Eiji
金额：
$ 7.3万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10558093/
关键词：
Ammonia DeNOx Low temperature DeNOx NOx SOx TiO_2 Al2O3 Metal Sulfate Metal Chroride Regeneration アンモニア脱硝 A_<12>O_3 NO_x・SO_x ZrO_2 細孔系分布 TPD 細孔径分布ポロシメーター

项目摘要

In order to develop a catalyst for low temperature selective reduction of NO with Ammonia, Al_2O_3, TiO_2, ZrO_2, and metal salts impregnated metal oxides as catalysts were studied in a continuous quartz fixed bed reactor system. It was observed that Al_2O_3, TiO_2 and ZrO_2 had an activity for selective catalytic reduction of NO at about 90℃. Their activity were influenced by reaction temperature, water vapor, sulfurous acid and ammonia gas. The selectivity of NO to N_2 over the metal oxides were in the order : ZrO_2>TiO_2>Al_2O_3. The activity of these three catalysts decayed with the elapsed reaction time since the accumulation of the ammonium salts plugged the pores of the catalysts. The activity decayed catalysts could be regenerated by water washing. Th mechanism of the selective catalytic reduction of NO with ammonia was also studied. The existence of SO_2 is indispensable to the selective catalytic reduction of NO at low temperature (90℃). SO_2 was supposed to contribute to the … More production of the active surface oxigen, which was significant to the reduction of NO with NH_3. The mechanism of low temperature reduction of NO to N_2 was proposed through an intermediate NH_4NO_2, which can be decompose to N_2 and H_2O below 100℃.From the study using metal salts supported Al_2O_3, TiO_2 or ZrO_2 catalyst, it was found that the activity of the metal chloride impregnated metal oxide catalyst was higher than that of the same sulfate if metal oxide was same. The activity of the catalyst depended on reaction temperature, ammonia concentration and the kind of support metal oxide. It was found that the SbCl_3, NiCl_2 and AlCl_3 supported Al_2O_3 were relatively high active among the catalysts. However the loading amount of SbCl_3 supported Al_2O_3 were negligible. From this result, it was supposed that the chloride ion remained over the Al_2O_3 contributed to its activity. For confirmation the hypothesis, the Al_2O_3 was treated with some HCl aqueous solution and concluded that the chloride ion accelerated the selective catalytic reduction of NO.The spent SbCl_3, NiCl_2 and AlCl_3 supported Al_2O_3 catalysts could not regenerated by water washing method because some amount of the salt was extracted by water. However, the spent HCl treated Al_2O_3 catalyst could be regenerated by water washing followed by retreatment with a HCl aqueous solution.The activity of the HCl treated Al_2O_3 catalyst is not enough to practical application to the next generation selective catalytic reduction process for NO removal. However, this catalyst is a new type catalyst for NO removal. If we can modified this catalyst and increase its activity, this new type catalyst is hopeful for practical use in the next generation process. Less

为了研制氨低温选择性还原NO的催化剂，在连续石英固定床反应器系统中对Al_2O_3、TiO_2、ZrO_2和浸渍金属氧化物的金属盐作为催化剂进行了研究。在90℃左右，Al_2O_3、TiO_2和ZrO_2具有选择性催化还原NO的活性。其活性受反应温度、水蒸气、硫酸和氨气的影响。NO对N_2的选择性依次为：ZrO_2>TiO_2>Al_2O_3。这三种催化剂的活性随着反应时间的延长而衰减，因为铵盐的积累堵塞了催化剂的孔。活性衰变催化剂可通过水洗再生。研究了氨选择性催化还原NO的机理。SO_2的存在是低温（90℃）选择性催化还原NO的必要条件。SO_2可以促进活性表面氧的生成，这对NH_3还原NO具有重要意义。提出了通过中间物NH_4NO_2将NO低温还原为N_2的机理，NH_4NO_2在100℃以下可分解为N_2和H_2O。通过对金属盐负载Al_2O_3、TiO_2或ZrO_2催化剂的研究发现，在金属氧化物相同的情况下，金属氯化物浸渍金属氧化物催化剂的活性高于相同硫酸盐的活性。催化剂的活性受反应温度、氨浓度和载体金属氧化物种类的影响。结果表明，SbCl_3、NiCl_2和AlCl_3负载的Al_2O_3催化剂活性较高。而SbCl_3负载Al_2O_3的负载量可以忽略不计。由此推测，残留在Al_2O_3表面的氯离子对其活性有贡献。为了证实这一假设，用盐酸溶液处理Al_2O_3，得出氯离子加速了NO的选择性催化还原的结论。废SbCl_3、NiCl_2和AlCl_3负载的Al_2O_3催化剂由于部分盐被水萃取而不能用水洗法再生。用HCl处理过的Al_2O_3催化剂可通过水洗再用HCl水溶液再处理再生。HCl处理的Al_2O_3催化剂的活性不足以实际应用于下一代选择性催化还原工艺中去除NO。该催化剂是一种新型的脱硝催化剂。如果我们能对这种催化剂进行改性，提高其活性，这种新型催化剂有望在下一代工艺中得到实际应用。少