载溴活性炭去除烟气中的单质汞

为提高活性炭对烟气中单质汞的吸附作用,利用溴对活性炭进行处理.通过对吸附容量和吸附动力学的测试,研究了载溴活性炭对气体中的单质汞的去除行为.结果表明,载溴可使活性炭对单质汞的吸附量显著增加,并加快对单质汞的吸附速率.实验条件下,当载溴量为0.33%时,活性炭对汞的饱合吸附量可增加约80倍,吸附容量达0.2mg/g;相对吸附系数增加了约40倍.溴负载量越高,吸附强化作用越显著.温度升高,载溴活性炭的吸附能力略有下降,烟气中的二氧化硫对单质汞的吸附速率略有抑制作用.     

ACF负载金属氧化物及尿素低温去除NO

以活性炭纤维(ACF)负载NiO以及NiO-CeO2制备了一系列催化剂,并在催化剂上负载尿素作为还原剂,研究其在30～120℃范围内的催化还原NO的活性.通过SEM、BET、XRD等表征实验选择性地对催化剂进行了理化特征研究.结果表明,3种不同质量分数的NiO催化剂中,5%NiO/ACF效率较低,10%NiO的催化剂活性以及活性稳定性较好,在90℃即可达到50%左右的NO净化效率,15%NiO/ACF的催化活性稳定性较差.在3种不同质量分数的NiO-CeO2/ACF催化剂中,5%NiO-5%CeO2/ACF的活性以及活性稳定性最好,在110℃可达到55%以上的NO净化效率.10%CeO2-5%NiO/ACF活性高于5%CeO2-10%NiO/ACF;活性金属的最佳负载量为10%,过多的负载量会引起催化剂比表面积的减少从而导致催化剂活性下降;金属氧化物是催化反应的活性中心.对10%CeO2/ACF、10%NiO/ACF和5%CeO2-5%NiO/ACF的研究显示,5%CeO2-5%NiO/ACF的催化活性最好,CeO2和NiO的协同作用使催化剂的活性优于2种单独负载的催化剂.本研究还对催化剂的低温催化机制进行了分析和讨论.     

过渡金属元素掺杂改性SCR对零价汞的催化氧化性能

为提高商用SCR催化剂对Hg0(零价汞)的催化氧化活性,研究了过渡金属对其进行掺杂改性的方法,并利用固定床反应平台考察了不同试验条件下改性催化剂对Hg0的氧化效率. 结果表明:Y、Zn、Ni和Zr等过渡金属的掺杂可明显抑制SCR催化剂的催化活性,而Fe、Cu掺杂改性SCR催化剂对Hg0的催化氧化性能有显著提升. 在反应温度为350 ℃、空速比为370 000 h-1、φ(HCl)为1×10-5的条件下,Fe、Cu掺杂改性的SCR催化剂对Hg0的氧化效率均能达到90%以上,并且Fe掺杂改性后的SCR催化剂的脱硝性能也未受到明显影响. 借助XRD和XPS等表征手段,对反应前后Fe掺杂改性SCR催化剂进行了研究,表明Fe改性SCR催化剂遵循Mars-Maessen和Langmuir-Hinshelwood机制,可明显提高对Hg0的催化氧化效率,因此,应用前景较好.      

腐殖酸定向修饰Ce-Co铁基生物焦汞吸附机理

使用腐殖酸对铁基改性生物焦进行定向修饰,并借助固定床吸附装置考察改性后生物焦汞吸附性能,探究了不同腐殖酸负载量下的铁基改性生物焦的汞吸附能力.采用BET、XPS、FTIR表征手段,考察了定向修饰后生物焦的孔隙结构、表面元素价态及表面功能基团的组成,通过SEM扫描电镜探究生物焦微观形貌,并利用EDS能谱分析生物焦表面活性金属成分分布.结果表明,使用腐殖酸对铁基改性生物焦定向修饰后的生物焦汞脱除性能大幅提高,使用5%质量分数包裹后的生物焦汞脱除性能最高,3h单位累积汞吸附量为18025ng/g,相较于未被修饰的铁基改性生物焦汞吸附性能提高65%;负载腐殖酸后的生物焦以介孔为主,表面活性金属种类丰富,有利于单质汞的氧化;样品表面羧基、醇羟基等含氧官能团数量增加,定向修饰后生物焦表面出现大量氨基等利于重金属吸附的含氮官能团;定向修饰后的生物焦表面出现团聚现象,包裹量过高会将生物焦表面活性位点完全包裹,阻碍了氧化还原反应的进行,不利于汞的进一步氧化;汞在生物焦表面的吸附过程同时存在化学吸附与物理吸附.     

Pt负载的铈锆固溶体的催化性能与表征

用柠檬酸法制备了CexZr1-xO(2x=0.5～1.0)铈锆固溶体,用浸渍法分别在铈锆固溶体上负载0.5%的Pt。用热重法(TG)测试了催化剂对碳烟的催化活性,Pt/Ce0.8Zr0.2O2显示了最高的催化活性。采用比表面(BET),X-射线衍射仪(XRD)和红外仪(FTIR)对催化剂进行了测试。结果表明:催化剂催化燃烧碳烟的活性与催化剂比表面积大小有关,可能是由于Pt在比表面积大的固溶体表面分散得更好,有利于氧溢出,促进碳烟的燃烧。     

Catalytic evaluation of promoted CeO2-ZrO2 by transition, alkali, and alkaline-earth metal oxides for diesel soot oxidation

Series of mixed metal oxides were synthesized by gel-combustion method and their catalytic activities for soot oxidation were investigated. The catalysts were M-Ce-Zr （M = Mn, Cu, Fe, K, Ba, Sr）, and χK-20Mn-Ce-Zr （χ= 0, 5, 10, 20）, they were characterized by XRD, SEM, TPR and BET surface area techniques. The results of soot temperature programmed oxidation （TPO） in an O2 oxidizing atmosphere indicate that K-Ce-Zr has the highest catalytic activity for soot oxidation under loose contact condition, due to enhancement of the soot and catalyst contacts. On the other hand, under a tight contact condition, Mn-Ce-Zr and Cu-Ce-Zr nano-composites have high activities for soot oxidation and lower the soot TPO peak temperatures by about 280 and 270℃, respectively, as compared to non-catalytic soot oxidation. Furthermore, the addition of up to 10 wt.% potassium oxides into Mn-Ce-Zr increases its catalytic activity and further reduces the soot TPO peak temperature by about 40℃ under loose contact condition.     

新型高效改性材料在重金属废水处理中的应用

使用原始吸附材料,如微生物、有机或无机材料等吸附废水中的重金属时,通常呈现较低的吸附性能,其吸附量通常都低于30mg/g。因此,研究者更多地关注提高各种吸附材料的吸附能力。国内外一些研究者采用新型、高效的物理或化学改性技术对吸附材料进行表面改造,如将高聚物接枝融合到菌体表面、表面分子印迹吸附剂、固定化微生物、酸改性处理有机或无机材料等,与常规材料相比,改性后材料对重金属的最大吸附容量一般可提高到100mg/g以上。随着各种改性技术的不断成熟,利用改性材料吸附重金属废水将成为今后研究重金属废水处理的主流方向。     

Transformation of mercury speciation through the SCR system in power plants

Coal-fired utility boilers are now identified as the largest source of mercury in the United States. There is speculation that the installation of selective catalytic reduction （SCR） system for reduction of NOx can also prompt the oxidation and removal of mercury. In this paper, tests at six full-scale power plants with similar type of the SCR systems are conducted to investigate the effect of the SCR on the transformation of mercury speciation. The results show that the SCR system can achieve more than 70%-80% oxidation of elemental mercury and enhance the mercury removal ability in these units. The oxidation of elemental mercury in the SCR system strongly depends on the coal properties and the operation conditions of the SCR systems. The content of chloride in the coal is the key factor for the oxidization process and the maximum oxidation of elemental mercury is found when chloride content changes from 400 to 600 ppm. The sulfur content is no significant impact on oxidation of elemental mercury.     

几种水合金属氧化物的磷酸根吸附性能

利用简单的碱沉淀法制备不同的水合金属氧化物,并对所得七种水合金属氧化物的磷酸根吸附等温线进行了系统的探讨比较.研究表明,25℃条件下,Al、Fe、Ni、Cu和Ce的水合金属氧化物对磷酸根的吸附最符合Langmuir线性吸附方程,而水合氧化锌和水合氧化钴吸附剂最符合线性等温线模型.所有这七种水合金属氧化物对磷酸根的吸附都...     

西维因在活性炭及草木灰上的吸附及解吸特性

在详细表征活性炭(AC)、草木灰(PA)和沉积物(S)表面性质及化学组成的基础上,研究他们对农药西维因的吸附等温线及吸附和解吸动力学特征.结果表明,化学组成类似,孔隙结构不同的碳吸附剂所遵循的吸附机理不同.介孔分布较多的AC吸附机理复杂,介孔分布较少的PA以线性分配作用为主,AC对西维因的吸附量远大于PA,表面积标化饱和吸附量显示,表面积是影响吸附量的关键因素.AC对西维因的解吸量远小于吸附量,与PA的解吸量相当,PA的解吸量与吸附量相近,且解吸动力学数据均能用准一级动力学方程拟合,说明以分配作用黏附于碳吸附剂上的西维因可能又以分配的形式解吸.沉积物(S)中掺混AC和PA后,对西维因的吸附量增加,解吸量降低,证明AC和PA均具有应用于污染沉积物治理的潜力,但复杂的沉积物体系使得吸附并非简单的叠加.     

Effect of oxidation treatment on the adsorption and the stability of mercury on activated carbon

Oxidation treatment on the adsorption and the stability of Hg on activated carbon （AC） was inrestigated. Both MnO2-AC and FeCl3-AC were produced during oxidation treatment. The measurement of modified AC＇s mercury adsorption capacity was conducted in a simulated coal-fired flue gas by adsorbing test apparatus. TCLP and column leaching methods were used to test the stability of mercury adsorbed on ACs. The results indicate that the oxidation treatment changed the pore structure of the AC and modified the carbon surface by creating chemical components such as MnO4^-, Mn^4＋, O, NO^3-, Fe^3＋, Cl^-, etc. The Hg sorption capacity on MnO2-AC or FeCl3-AC was about three times higher than that of untreated carbon. In addition, the mercury control cost of each of the formers was about the half cost of the untreated carbon. The stability of Hg absorption was studied, it found that mercury adsorbed on the oxidation treated AC was not better than that of untreated carbon. It could concluded that the insoluble form of Hg is very important to the stability of mercury adsorbed on AC. This study suggests that the FeCl3-AC is the best absorbent for Hg with high adsorption capacity, better Hg adsorption stability in leaching environment, and lower cost among the three ACs tested.     

Systematic control technologies for gaseous pollutants from non-ferrous metallurgy

Air pollutant emissions represent a critical challenge in the green development of the non-ferrous metallurgy industry.This work studied the emission characteristics,formation mechanisms,phase transformation and separation of typical air pollutants,such as heavy metal particles,mercury,sulfur oxides and fluoride,during non-ferrous smelting.A series of purification technologies,including optimization of the furnace throat and hightemperature discharge,were developed to collaboratively control and...     

过渡金属催化剂对邻二氯苯的催化氧化研究

以过渡金属的氧化物制得催化剂系列 ,研究其对邻二氯苯的氧化活性 ,考察反应温度、催化剂负载量、空间速度对氧化过程的影响 ,过渡金属氧化物对邻二氯苯的氧化活性顺序为 :CrOx>CuOx >VOx >MnOx >MoOx。 5wt.%V 1 0wt.%Mo3wt.%Mn/Al2 O3催化剂在 350℃时对邻二氯苯转换率达到了 90 %以上。     

燃煤烟气污染物控制装置协同脱汞特性研究

采用Ontario Hydro方法对某100MW燃煤机组进行了烟气汞取样测试,获得了选择性催化还原（SCR）脱硝装置、静电除尘器（ESP）和湿法烟气脱硫装置（WFGD）对烟气汞形态转化和脱除特性规律.借助程序升温脱附（TPD）、扫描电子显微镜分析（SEM）和X射线荧光光谱分析（XRF）等方法探究了飞灰对汞的吸附特性及吸附后汞的热稳定性.结果表明,在75% MCR和85% MCR不同的机组负荷下,SCR+ESP+WFGD对烟气总汞（Hg^T）的联合脱除率分别为92.83%、81.66%.SCR对元素汞（Hg⁰）的氧化率与燃煤氯（Cl）含量正相关,Cl含量为500mg/kg时,氧化率高达96.18%.ESP在完全脱除颗粒汞（Hg^P）的同时对Hg⁰和氧化态汞（Hg²⁺）的平均脱除率分别为12.73%和27.79%,ESP飞灰中的未燃尽炭和金属氧化物（Al₂O₃、Fe₂O₃）是吸附气态汞的关键组分,汞在飞灰表面主要以HgCl₂、HgS（红色）和HgO的形态存在,高于190℃时会分解再释放.WFGD对Hg²⁺的平均脱除率为91.10%,并能将部分Hg²⁺还原成Hg⁰,存在明显的汞二次释放问题.     

Adsorptive removal of heavy metal ions from industrial effluents using activated carbon derived from waste coconut buttons

Removal of heavy metal ions from industrial effluents by the activated carbon prepared by steam activation of waste coconut buttons through batch adsorption process.     

V2O5/AC在含SO2气氛中对气态Hg0的吸附脱除研究

利用固定床反应器研究了模拟烟气(N_2、SO_2、O_2)气氛下,气态Hg~0在V_2O_5/AC催化剂上的吸附脱除行为.考察了V_2O_5担载量、SO_2浓度和吸附温度等对V_2O_5/AC吸附脱除Hg~0的影响,并对V_2O_5/AC上吸附汞的形态进行了XPS分析表征.研究发现,V_2O_5/AC对Hg~0的吸附能力远大于载体AC.汞的吸附量与V_2O_5/AC中V_2O_5的质量分数有关,随着V_2O_5质量分数从0.5%增加到1.0%,汞的吸附量从75.9 μg·g~(-1)增加到89.6 μg·g~(-1) (无氧) 和115.9 μg·g~(-1)增加到185.5 μg·g~(-1) (有氧),远高于相同吸附条件下的AC上的汞吸附量 (9.6 μg·g~(-1)和23.3 μg·g~(-1)).SO_2对Hg~0的吸附有促进作用,主要是由于SO_2和Hg~0在V_2O_5/AC上发生了化学反应.但是当SO_2体积分数从500×10~(-6)增加到2 000×10~(-6)时,V_2O_5/AC对汞的吸附量只增加了5%.不同温度下的实验结果表明,V_2O_5/AC催化剂在150℃左右的吸附脱除Hg~0的能力最高,汞的吸附量达到98.5 μg·g~(-1) (无氧) 和187.7 μg·g~(-1) (有氧).XPS 分析结果表明,在V_2O_5/AC催化剂表面有HgO和HgSO_4生成,证实了V_2O_5和SO_2的作用.     

低温SCR脱硝催化剂过渡金属氧化物改性及硫中毒失活机制研究

以浸渍法制备MnOx-CeOx/ACF催化剂.在110~230℃温度范围内,MnOx-CeOx/ACF催化剂具有较好地低温选择性催化还原脱除NOx的活性.结果表明,该催化剂在150℃和230℃的脱硝效率分别达到80%和90%.加入Fe、Cu和V等过渡金属氧化物对MnOx-CeOx/ACF催化剂进行改性.该类过渡金属氧化物的加入对MnOx-CeOx/ACF的活性具有抑制作用.相比于MnOx-CeOx/ACF以及Cu和V改性的催化剂,Fe改性催化剂在一定时期内具有良好的抗SO2性能.在SO2存在下,Fe改性催化剂在初始6h内其脱硝效率保持在75%以上.X射线光电子能谱(XPS)和傅立叶转换红外光谱(FTIR)分析结果表明,催化剂失活包括两部分机制,一是形成硫酸铵盐,可粘附在催化剂表面使催化剂失活;另外一个机制是作为活性成分的锰铈等金属氧化物被SO2硫化形成金属硫酸盐.     

复合金属氧化物Cu-Co-Al低温催化水解HCN

采用共沉淀法制备了Cu-Al、Co-Al和Cu-Co-Al复合金属氧化物催化剂,考察了3种催化剂对HCN的催化水解性能,并通过XRD、BET、XPS和H2-TPR等对催化剂的结构和性能进行表征.结果表明, Cu-Co-Al催化剂展示最高的催化活性. 反应温度200℃,反应180min后, Cu-Co-Al、Cu-Al和Co-Al催化剂对HCN的转化率分别为95%,90%,10%;NH3生成量分别为122,118,18mg/m3.低结晶度、高分散性、高比表面积的催化剂有利于低温HCN水解.适量的表面分子氧含量、较高的Cu2+和Co3+含量、较低的还原温度是Cu-Co-Al催化剂具有较高的HCN低温水解活性的主要原因.     

Review of post-combustion carbon dioxide capture technologies using activated carbon

Carbon dioxide(CO_2) is the largest anthropogenic greenhouse gas(GHG) on the planet contributing to the global warming. Currently, there are three capture technologies of trapping CO_2 from the flue gas and they are pre-combustion, post-combustion and oxy-fuel combustion. Among these, the post-combustion is widely popular as it can be retrofitted for a short to medium term without encountering any significant technology risks or changes.Activated carbon is widely used as a universal separation medium with series of advantages compared to the first generation capture processes based on amine-based scrubbing which are inherently energy intensive. The goal of this review is to elucidate the three CO_2 capture technologies with a focus on the use of activated carbon(AC) as an adsorbent for post-combustion anthropogenic CO_2 flue gas capture prior to emission to atmosphere. Furthermore, this coherent review summarizes the recent ongoing research on the preparation of activated carbon from various sources to provide a profound understanding on the current progress to highlight the challenges of the CO_2 mitigation efforts along with the mathematical modeling of CO_2 capture. AC is widely seen as a universal adsorbent due to its unique properties such as high surface area and porous texture. Other applications of AC in the removal of contaminants from flue gas, heavy metal and organic compounds, as a catalyst and catalyst support and in the electronics and electroplating industry are also discussed in this study.     

铁铜催化剂非均相Fenton降解苯酚及机制研究

通过浸渍法制备了负载于活性炭(AC)上的金属催化剂Fe/AC、Cu/AC和Fe-Cu/AC,并通过X射线衍射(XRD)、物理吸附仪及X射线光电子能谱(XPS)对其进行了表征.研究了非均相Fenton反应催化H2O2降解苯酚废水的工艺参数,并通过中间产物分析和电子自旋共振谱(ESR)探讨了过程反应机制.实验表明,Cu/AC催化剂中铜主要以CuO形式存在,Fe/AC中铁以多价态形式存在,以无定形形态分散于活性炭中.Fe/AC、Cu/AC和Fe-Cu/AC催化过氧化氢降解苯酚60 min内降解率分别达到96.7%、77.5%和99%;Cu/AC和Fe-Cu/AC催化剂中活性组分铜和铁有一定溶出,而Fe/AC中活性组分铁溶出很少,苯酚降解主要是以非均相催化为主,同时在三轮循环实验后的苯酚降解率仍然高达93%以上,显示了良好的催化稳定性.在优化条件pH=3、T=303 K及初始H2O2为4.38 mmol.L-1下,Fe/AC催化过氧化氢对苯酚和TOC去除率分别达到97%和53%,没有催化剂时苯酚几乎不降解.ESR结果表明Fe/AC催化过氧化氢产生了羟基自由基,证明苯酚降解是以羟基自由基氧化为主;通过高效液相色谱(HPLC)检测苯酚降解中间产物主要有邻苯二酚、对苯二酚和对苯醌,推测苯酚降解途径主要为邻位和对位的羟基取代反应.