燃煤电厂脱硝催化剂失活原因分析与再生技术研究

发布时间：2018-05-25 10:14

  本文选题：氮氧化物 + 催化剂　； 参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：煤炭是我国最主要的一次能源,在煤炭的使用过程中不可避免的产生了大量污染物。氮氧化物作为其中之一,会造成酸雨、光化学烟雾以及其他环境问题。据统计,我国氮氧化物排放的67%来源于煤炭为主的化石燃料的燃烧。因此,燃煤电厂氮氧化物控制是我国氮氧化物控制的重点。选择性催化还原法是目前燃煤电厂应用最广泛的脱硝技术,催化剂是SCR技术的核心。目前商业应用最广泛的是V-W-Ti型催化剂。由于催化剂成本较高,且通常运行3~5年就因失活需要更换,造成火电厂运行成本增加,同时废弃的催化剂会引起新的环境问题。因此,开展催化剂的失活分析及再生工作是十分必要的。目前主要的再生方法包括水洗再生,酸洗再生,热(还原)再生和复合再生。本文以商用V-W-Ti型催化剂为研究对象,分析了其失活原因,在此基础开展了再生研究,主要结论如下:(1)旧催化剂脱硝效率下降明显,400℃时达到最大脱硝效率63.1%,明显低于新催化剂的脱硝效率,说明旧催化剂已经失活。对新、旧两种催化剂分别作了SEM、N2吸附脱附、XRD、XRF、FTIR等表征。结果表明:旧催化剂晶型未发生改变,仍为典型的锐钛矿,催化剂未发生烧结现象。旧催化剂发生了孔堵塞,导致比表面积减小,平均孔径增加,孔体积减小。同时,相对于新催化剂,旧催化剂中存在活性成分流失现象,Na、Ka、Ca、Mg等毒性元素含量明显增加,新增了As元素。孔堵塞、碱金属碱土金属及砷中毒、活性成分流失是造成催化剂失活的主要原因。(2)制定了再生工艺路线:水洗、酸洗、再生浸渍。考察了水洗方式、水洗时间、酸液浓度、酸洗时间、再生液浓度及再生时间对催化剂再生的影响。超声水洗效果优于浸渍水洗,超声水洗时45 min为最佳清洗时间。0.5 mol/L的H2SO4溶液具有最佳的酸洗效果,45 min为最佳酸洗时间。硫酸氧钒、仲钨酸铵质量分数分别为2%、2%为最佳再生液。60 min最为最佳再生浸渍时间。再生后催化剂脱硝效率最高可达91.6%,达到新鲜催化剂脱硝效率的95%。
[Abstract]:Coal is the most important primary energy in China, which inevitably produces a large number of pollutants in the process of coal use. Nitrogen oxides, as one of them, can cause acid rain, photochemical smog and other environmental problems. According to statistics, 67% of nitrogen oxide emissions in China come from the combustion of coal-based fossil fuels. Therefore, the control of NOx in coal-fired power plants is the key point of NOx control in China. Selective catalytic reduction is the most widely used denitrification technology in coal-fired power plants at present, and catalyst is the core of SCR technology. At present, the most widely used commercial catalyst is V-W-Ti catalyst. Because of the high cost of the catalyst and the replacement of the catalyst after 3 ~ 5 years of operation, the operation cost of the thermal power plant is increased, and the abandoned catalyst will cause new environmental problems. Therefore, it is necessary to carry out deactivation analysis and regeneration of catalyst. At present, the main regeneration methods include washing regeneration, acid cleaning regeneration, hot (reducing) regeneration and compound regeneration. In this paper, the reason of deactivation of commercial V-W-Ti catalyst was analyzed, and regeneration research was carried out on this basis. The main conclusions are as follows: (1) the denitrification efficiency of the old catalyst decreased obviously to 63.1% at 400 鈩，

本文编号：1933056