Fe、Ce、Cu对Mn/AC催化剂低温脱硝及抗硫性能的影响研究

通过浸渍法制备了Fe、Ce、Cu和Mn含量比不同的系列金属-Mn/AC催化剂,利用XRD、BET、SEM等进行了表征,对其NH_3-SCR低温脱硝性能和抗硫性能进行了研究。结果表明,金属改性对Mn/AC催化剂的低温脱硝性能和抗硫性能均有较大提升,改性后的催化剂比表面积增加,孔径、孔容降低,其中Fe(15)Mn(10)/AC催化剂表现最好,铁和锰均能以无定形氧化物良好分散于载体表面,该催化剂具备丰富的酸性位,良好的氧化还原性能,在120～200℃下脱硝效率均可达90%,在通入SO_2条件下,仍有70%的脱硝效率,并且经济性适中,便于推广。     

Ce/AC低温脱硝催化剂的性能研究

以40％硝酸处理的活性炭为载体,通过浸渍法制备一系列Ce/AC催化剂.采用传统的固定床反应装置,氨气作还原气体,考察了温度、铈负载量、NH3/NO（摩尔比）、氧含量、空速、H2O等不同条件下NO的转化率.实验表明,温度在120℃、Ce的负载量为5％、空速为10000h-1时,催化剂对NO的转化率高达97％,150℃时可达100％.     

Ce改性Fe2O3/AC催化剂低温SCR脱硝性能

以活性焦(AC)为载体、Fe和Ce为活性组分,采用等体积浸渍法制备了Fe2O3/AC和Ce?Fe2O3/AC催化剂,研究了Fe含量及Ce掺杂对Fe2O3/AC催化剂低温脱硝性能的影响,并对催化剂进行了表征. 结果表明,当Fe负载量为6wt%时,Fe2O3/AC催化剂的NOx转化率最高,240℃下达93.9%. 掺杂Ce后Ce?Fe2O3/AC催化剂的催化效率明显提高,当质量比Ce:Fe=0.5:6时,NOx转化率较高,120~200℃下NOx转化率比负载6wt% Fe的催化剂提高了5%?20%,且抗硫性能较好,240℃下通入100?10?6(vol) SO2,NOx转化率稳定在94.1%. 掺杂少量Ce可使γ-Fe2O3均匀分散在催化剂表面,且表面吸附氧Oα比例增大,催化剂的还原性增强,促进了选择性催化还原反应进行.     

Fe、Ce掺杂六铝酸盐催化剂制备及脱硝抗硫性能

用共沉淀法制备六铝酸盐催化剂LaM_xAl_12-xO_19-δ(M=Fe、Ce、FeCe)。用XRD、H₂-TPR以及NO转化率对催化剂进行表征和活性验证,分析不同离子取代Al³⁺对六铝酸盐结构和脱硝抗硫活性的影响。结果表明,Fe离子易于进入六铝酸盐晶格,形成完整的六铝酸盐结构,LaFeAl₁₁O_19-δ催化剂具有良好的低温脱硝活性。Ce离子不易进入六铝酸盐晶格,主要以CeO₂的形式存在,LaCeAl₁₁O_19-δ催化剂有良好的高温脱硝活性。加入SO₂后,两种催化剂都有不同程度的失活现象,其中,LaFeAl₁₁O_19-δ催化剂失活较为明显。LaFeCeAl₁₀O_19-δ催化剂中,Fe离子和Ce离子间会产生协同作用,提高了催化剂的脱硝抗硫活性。     

提高Mn系低温脱硝催化剂抗硫抗水性能的国内外研究概述

介绍了氮氧化物的来源、SCR脱硝的反应机理和工艺流程、催化剂的硫和水中毒机理,重点介绍了国内外学术和工业界为提高催化剂抗硫和抗水性能所做的研究和尝试,旨在推动低温SCR技术的进展,促进该技术早日实现在工业上的大规模应用。     

Mn、Ce负载顺序对催化剂Mn-Ce/TiO2低温脱硝活性的影响

采用溶胶凝胶法制备了一系列Mn-Ce/TiO₂催化剂样品, 并用比表面积及孔径分析仪(BET)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)等对催化剂进行了表征, 考察了活性组分Mn、Ce负载顺序对催化剂结构的影响, 并在固定床连续流动反应器上对其催化活性进行了评价。结果表明, 催化剂晶相均为锐钛矿型结构, Mn、Ce活性组分在载体表面高度分散或形成了无定形结构;Mn、Ce同时负载时催化剂表面活性组分分布均匀, 比表面积最大, 为97.6m²/g, 且催化剂孔径分布以中孔为主;Mn、Ce同时负载时催化剂活性最好, 反应温度为200℃时, NO转化率达到90%以上。     

Fe2O3/AC催化剂的低温选择性催化还原脱硝性能

以活性焦(AC)为载体、Fe2O3为活性组分,采用等体积浸渍法制备Fe2O3/AC催化剂,研究了Fe含量对Fe2O3/AC催化剂低温脱硝性能的影响. 结果表明,当Fe负载量为6wt%时能获得比其它负载量更佳的NOx转化率,尤其在240℃时NOx转化率达93.9%,当分别有120?10?6(vol) SO2和3.5vol H2O存在时,脱硝率分别稳定在约86%和74%;催化剂孔径≤4 nm,随Fe负载量增加,孔径呈增大趋势;催化剂较稳定;Fe主要以γ-Fe2O3分散在催化剂表面,负载适量Fe2O3使表面吸附氧Oβ和Fe3+增多,为催化剂提供更多活性位,提高了Fe2O3/AC催化剂的低温选择性催化还原脱硝活性.     

载体预处理对Fe-Mn/AC催化剂低温脱硝活性的影响

以活性炭为载体,采用硝酸及热处理对载体进行预处理,用浸渍法制备Fe-Mn/AC催化剂,通过FTIR、SEM、N_2吸附-脱附、NH_3-TPD、H_2-TPR和XPS等进行表征,考察载体预处理对催化剂脱硝活性的影响。结果表明,载体预处理会影响载体的官能团、酸位、孔结构及比表面积等,进而影响活性组分的价态及分散性,活性组分的高价态和高分散性是其低温具有高活性的主要原因,载体经硝酸及300℃热处理的催化剂在140～250℃内活性提高近38%。     

载体预处理对Fe-Mn/AC催化剂低温脱硝活性的影响

以活性炭为载体,采用硝酸及热处理对载体进行预处理,用浸渍法制备Fe-Mn/AC催化剂,通过FTIR、SEM、N_2吸附-脱附、NH_3-TPD、H_2-TPR和XPS等进行表征,考察载体预处理对催化剂脱硝活性的影响。结果表明,载体预处理会影响载体的官能团、酸位、孔结构及比表面积等,进而影响活性组分的价态及分散性,活性组分的高价态和高分散性是其低温具有高活性的主要原因,载体经硝酸及300℃热处理的催化剂在140～250℃内活性提高近38%。     

锰基低温NH3-SCR催化剂脱硝及抗硫性能研究进展

催化剂是SCR脱硝的核心技术,在SCR脱硝系统中,经除尘和脱硫后烟气温度通常低于200℃,因此开发低温脱硝催化剂为研究重点。本文分别综述了非负载型和负载型锰基低温脱硝催化剂,其中主要探讨了TiO_2、活性炭、炭纳米管、 CeO_2为载体的负载型锰基低温脱硝催化剂。分析了SO_2中毒过程以及抗中毒的催化剂。并对锰基低温脱硝催化剂进一步研究方向进行了展望。     

Optimizing calcination temperature of Fe/activated carbon catalysts for CWPO

The influence of the calcination temperature (within the temperature range 150–300 °C) on the chemical nature of the surface as well as on the activity of an own-made Fe/AC catalyst for catalytic wet peroxide oxidation (CWPO) has been studied. The catalyst surface was characterized by means of TG, TPD and N₂ adsorption/desorption analysis. The presence of iron promotes the oxidation of the activated carbon surface, increasing the amount of oxygen surface groups, mainly carboxylic acid, anhydride and lactone groups. On the other hand, the calcination step modifies the distribution of these groups, increasing the amount of lactone groups and reducing the pH_slurry. Within the temperature range studied, the calcination temperature does not affect to the porous structure. The changes observed in the catalyst surface led to an increase of the catalytic activity as a consequence of a higher H₂O₂ decomposition into OH radicals, probably due to a better dispersion of the active phase. Neither oxygen surface groups by themselves nor pH_slurry seemed to have influence on the catalytic activity.     

硬脂酸钙和硬脂酸锌对PVC/AC配方体系发泡温度的影响

在软质PVC基体材料中,分别测定了硬脂酸钙和硬脂酸锌两种发泡促进剂与主发泡剂AC在不同配比下的发泡温度。结果表明,随促进剂/AC质量比的增加,AC分解温度可以在一定程度上降低;硬脂酸钙/AC的质量比从0∶1增加到4∶1时,可以使AC的发泡温度从182℃降至168℃;硬脂酸锌/AC的质量比从0∶1增加到3∶1时,可以使AC的发泡温度从185℃降至166℃;某些配比下温度的变化不明显,有时有波动甚至突变。     

沉淀方式对二乙醇胺催化脱氢铜锰催化剂性能的影响

研究了沉淀方式对铜锰催化剂二乙醇胺脱氢反应性能的影响,并采用XRD和H_2-TPR分别对催化剂结构和还原性能进行了表征。结果表明,分步沉淀法制备的催化剂对二乙醇胺脱氢具有更高的活性(91.9%)和亚氨基二乙酸选择性(96.2%),有利于改善锰溶出的影响,催化剂重复使用率高。H_2-TPR研究发现,分步沉淀法制备的催化剂具有更好的还原性能;XRD测试表明,分步沉淀法有利于催化剂中CuO的分散。     

水蒸气对MnOx/MWCNTs低温SCR脱硝催化剂的影响

为考察MnOx/MWCNTs催化剂抗水效果,实验研究了水蒸气对其低温NH3-SCR脱硝性能的影响,并通过比表面积(BET),程序升温还原(TPR)和热重(TG)等多种手段对催化剂的结构进行了表征.结果表明,水蒸气存在下,催化剂低温活性明显受到抑制,NOx最高转化率温度向高温方向偏移约30℃.随着水蒸气体积分数的增加和反...     

改性方法和助剂CeO2对CuO/AC催化剂脱硫性能的影响

采用等体积浸渍法制备了CuO/AC及CuO-CeO₂/AC双金属催化剂,金属氧化物的前驱体为不同浓度的Cu(NO₃)₂及Ce(NO₃)₃溶液。CuO-CeO₂/AC双金属氧化物催化剂采用分步浸渍法,对制得的催化剂进行模拟烟气脱硫性能比较。通过SEM和X射线衍射等手段对催化剂表面形貌和表面晶相进行分析。结果表明,添加质量分数1%CeO₂助剂的CuO/AC催化剂脱硫效果最好,因为助剂CeO₂能够使CuO在催化剂表面有更高的分散度,负载金属氧化物催化剂的脱硫活性顺序为：CuO-CeO₂/AC＞CuO/AC。     

Combined effect of H2O and SO2 on V2O5/AC catalysts for NO reduction with ammonia at lower temperatures

Combined effect of H₂O and SO₂ on V₂O₅/AC the activity of catalyst for selective catalytic reduction (SCR) of NO with NH₃ at lower temperatures was studied. In the absence of SO₂, H₂O inhibits the catalytic activity, which may be attributed to competitive adsorption of H₂O and reactants (NO and/or NH₃). Although SO₂ promotes the SCR activity of the V₂O₅/AC catalyst in the absence of H₂O, it speeds the deactivation of the catalyst in the presence of H₂O. The dual effect of SO₂ is attributed to the SO₄²⁻ formed on the catalyst surface, which stays as ammonium-sulfate salts on the catalyst surface. In the absence of H₂O, a small amount of ammonium-sulfate salts deposits on the surface of the catalyst, which promote the SCR activity; in the presence of H₂O, however, the deposition rate of ammonium-sulfate salts is much greater, which results in blocking of the catalyst pores and deactivates the catalyst. Decreasing V₂O₅ loading decreases the deactivation rate of the catalyst. The catalyst can be used stably at a space velocity of 9000 h⁻¹ and temperature of 250 °C.     

The synthesis of alcohols using Cu/ZnO/A12O3 + (Ce or Mn) catalysts

Cu/ZnO/A1₂O₃ catalysts modified by compounds of manganese or cerium were prepared by coprecipitation or by impregnation and were tested for the synthesis of alcohol mixtures from synthesis gas at pressures of up to 70 bar. They were also examined by XPS both before and after the reaction. With both the impregnated and the coprecipitated catalysts, manganese increased the selectivity to higher alcohols (mainly isobutanol). However, in the case of cerium, the location of the cerium ions appeared to determine the selectivity; it shifted towards alkanes and C0₂ when cerium was present at the surface of the catalyst (probably as Ce0₂), but to isobutanol when the cerium ions were present in the bulk. Changes were found in the selectivities of the catalyst doped with cerium with time on stream and these could be explained by a segregation of the cerium ions to the surface. Some of the mechanistic steps in the formation of higher alcohols as proposed in the literature were confirmed.     

Fe2O3/AC催化剂上对甲基苯硫酚的水相催化氧化偶联

以对甲基苯硫酚为模型底物，空气为氧化剂，来研究硫醇水相催化氧化偶联制备二硫醚。以活性炭为载体，采用等体积浸渍法制备了一系列负载型氧化物催化剂，并考察了其在对甲基苯硫酚氧化偶联制备对甲苯二硫醚反应中的催化性能。反应结果表明，活性炭负载的铁氧化物具有最佳催化性能。采用N₂物理吸附、X射线衍射、X射线光电子能谱和透射电镜等表征手段对活性炭负载的铁氧化物催化剂进行了表征。表征结果表明，铁氧化物为高度分散在活性炭上的Fe₂O₃物种。以Fe₂O₃/AC为催化剂，当催化剂焙烧温度为400℃，Fe负载量为5%，在50℃下反应30min时，对甲苯二硫醚的收率高达97.4%；该催化剂循环使用5次后活性无明显下降。