印染废水膜后浓水的深度处理工艺研究

采用Fenton法+反硝化生物滤(DN)池的深度处理工艺处理印染废水膜后(RO)浓水,考察了H2O2加药量、FeSO4.7H2O加药量、初始pH值和反应时间对Fenton法去除COD的影响,以及C/N、水力停留时间(HRT)对DN池去除NO3--N的影响.研究结果表明:在初始pH值为4,FeSO4·7H2O和H2O2的投加量分别为450mg/L、90mg/L,反应时间为1.5h时,COD去除率达到62％,出水COD71mg/L,色度15倍;DN池在C/N为8,HRT为2h时,出水NO3--N降低至0.52mg/L,NO3--N去除率达到96.8％.RO浓水经上述工艺处理后出水水质稳定达到《纺织染整工业水污染物排放标准》(GB4287-2012)表2限值.     

柴油机排气组分对低温等离子体转化NO的影响

自制了介质阻挡放电型低温等离子体反应器,设计了低温等离子体柴油机模拟排气处理系统,研究了低温等离子体作用下O2、C3H6和水蒸气对NO氧化转化的影响及NO在N2中的还原转化.研究表明:NO在N2气氛中的还原转化率低,能耗大;模拟气中存在O2时,NO向N2的还原转化率降低,NO向NO2的氧化转化率大幅提高;排气中的H2O在低温等离子体作用下生成OH强氧化性粒子,促进NO向NO2的氧化转化;HC的存在可提高NO向NO2的氧化转化,并能有效降低NO向NO2的转化能耗.总之,在柴油机富氧排气环境中,低温等离子体很难直接将NO转化为N2,但可有效地将NO氧化为NO2及硝酸盐,为催化剂催化还原NOx创造条件.     

铂基催化剂快速部分催化氧化甲烷的研究

以Al 2O 3为载体,采用浸渍法制备Pt/Al 2O 3催化剂,通过测量重整反应过程中催化剂的温度分布情况,研究了改变甲烷快速部分氧化重整反应中反应条件(反应气体预混合温度、N 2体积比例、CH 4/O 2比)对反应物的转化率及产物选择性的影响。研究发现,催化剂床层温度的上升可以促进CH 4的转化,使H 2和CO的选择性升高且H 2与CO的物质的量的比(简称H 2/CO比,依此类推)升高。N 2体积比例及CH 4/O 2比的升高,会降低催化剂床层温度,进一步造成CH 4的转化率和H 2/CO比降低,但与仅降低混合气预热温度不同的是,提高N 2体积比例及CH 4/O 2比会造成H 2和CO的选择性升高,这可能是催化剂表面的活性氧导致的。通过对甲烷在Pt催化剂上的反应机理进行了初步讨论,认为甲烷的快速部分催化氧化反应为多种反应路径共存,不同的反应条件下各种反应路径所占比例会发生变化。     

流化床燃烧中N_2O的排放控制研究进展

N2O是一种既会破坏臭氧层又可以造成温室效应的大气污染物。化石燃料的燃烧是人类活动产生N2O的主要来源。煤炭燃烧特别是运行温度为850~950℃的流化床燃烧会排放大量的N2O。简要阐述了流化床燃烧过程中N2O的生成、分解机理和影响N2O生成量的各种因素,以及减少N2O排放量的技术措施,特别是介绍了流化床脱硝技术——选择性非催化还原(SNCR)过程中的N2O控制研究进展,并对各种控制排放技术前景进行了展望。     

NaOH作添加剂对NO_xOUT工艺的试验影响

对NaOH作添加剂对尿素作还原剂的选择性非催化还原(NOxOUT)脱硝工艺的影响进行了试验研究。无添加剂时,在780℃～1 000℃范围内随温度升高,NO的浓度先降低后升高,N2O浓度先升高后降低,转折点为900℃。随着氨氮比增大,NO去除率增大,N2O浓度也随之升高,总的NOx去除率由于N2O的影响提高不明显。有NaOH作添加剂时,随着NaOH的添加量的增大,N2O的浓度逐渐减小,NO的浓度在较低温度时,先减小后增大,较高温度时,一直增大,但变化幅度要比N2O小。在氨氮比为1.5且有NaOH作添加剂时,900℃条件下可得到73.48%的总NOx去除率。NaOH对工艺的影响是产生活性基元和去除尿素分解生成的HNCO联合作用,后者作用较大。因尾气中钠盐主要以NaNCO形式存在,由此引起的烟气碱性增大的程度并不严重。     

气体微波放电转化NO的模拟实验研究

对模拟烟气系统的微波放电转化NO过程进行了数值模拟,分析了影响NO转化率和N2、NO2选择性的因素及规律。研究结果表明:在He+NO+O2系统中,40 W微波功率下,NO总转化率可达77%,其中59%转化为N2,18%转化为NO2。微波功率、NO初始浓度和O2初始浓度等对NO转化率及N2、NO2的选择性有一定的影响。微波功率对NO转化率影响不大,但微波功率的增大有利于NO向N2的转化、提高N2选择性。NO初始浓度的增加降低了体系的NO转化率。O2的加入使产物中NO2的量增加,但NO转化为N2的转化率总大于其转化为NO2的转化率。屏蔽O自由基和N自由基均降低了NO的转化率,有O无N使NO主要转化为NO2,有N无O有利于NO向N2的转化。     

N2O在锰系低温催化剂上的生成途径

实验对比了由浸渍法、共沉淀法以及溶胶凝胶法制备的锰系低温催化剂在选择性催化还原(SCR)反应中的差异,发现溶胶凝胶法制备的催化剂在整个测试区间内都具有最高的脱硝效率,但是也有最多的 N2O 生成。针对溶胶凝胶法,进一步研究了N2O在SCR过程中的生成情况。发现N2O主要来源于NH3的直接氧化以及NH3和NO的反应,后者为N2O的主要生成途径。添加Ce、V后,随着反应温度升高,NH3的直接氧化逐步成为N2O主要来源。     

轿车柴油机燃用生物柴油时温室气体排放特性的研究

对轿车柴油机燃用大豆酸化油制生物柴油进行了试验研究,探讨了在外特性、标定转速负荷特性及最大扭矩转速负荷特性下尾气中CO2、CH4、N2O及当量CO2温室气体排放的变化规律.结果表明:轿车柴油机的CH4和N2O排放量均很小,CO2是其主要温室气体排放;随着生物柴油混合比例的增加,发动机的CO2和CH4排放降低,N2O升高,生命周期当量CO2排放降低.大豆酸化油制生物柴油能在一定程度上降低轿车柴油机的温室气体排放.     

H_2O对CO在0.5%PdZrO_2/γ-Al_2O_3上催化燃烧特性的影响

以0.5%PdZrO_2/γ-Al_2O_3为催化剂,在所搭建的比例积分微分控制(PID)多功能实验装置上进行CO催化燃烧基础特性实验,分析了H_2O对CO转化率的影响,以及H_2O体积分数的变化对CO转化率和CO催化燃烧反应时间的影响.结果表明:H_2O的加入大幅提升了CO在催化剂上的起燃温度和燃尽温度,增大了CO催化燃烧反应所需的活化能,且随着H_2O体积分数的增大,CO起燃温度和燃尽温度逐步升高;CO转化率随H_2O体积分数的增加逐渐降低;CO反应稳定所需时间随H_2O体积分数的增大而增加;H_2O的存在降低了催化剂的活性,抑制了催化燃烧的进行.     

等离子体辅助La0.9 K0.1 CoO3同时催化去除NOx和柴油机碳烟微粒的试验研究

通过在γ—Al2O3小球上涂覆复合金属氧化物La0.9K0.1CoO3，利用等离子体辅助催化程序升温反应(TPR)技术，对同时催化去除柴油机NOx和碳烟微粒反应进行了研究，并对其化学机理进行了探讨．研究结果证实，在富氧环境中，不论是在催化程序升温还是在等离子体一催化程序升温中，CO2和N2的形成出现在相同的温度范围内，等离子体加强了同时催化去除NOx和碳烟微粒的反应特性，降低了碳烟微粒的燃烧温度，提高了NOx还原为N2的效率，也提高了低温和高温段NOx的分解，从而提高了总的NOx转化效率．     

基于蒙特卡洛算法的SCR脱硝性能影响因素分析

为分析入口参数不均匀分布对选择性催化还原(Selective Catalytic Reduction, SCR)反应器脱硝性能的影响,通过MATLAB编程的方法建立了SCR脱硝反应三维数值模型。采用蒙特卡洛算法生成入口边界,以此调用模型,研究入口速度、温度及氨氮比分布不均条件下脱硝效率及氨逃逸率的变化规律。结果表明：当入口速度超过1.5 m/s,速度偏差对脱硝效率及氨逃逸率的影响较为显著,在入口速度为4 m/s时将速度偏差由0增大到80%,脱硝效率由46.77%降低到44.67%,而氨逃逸率由8.31%增加到12.57%;不同温度偏差变化区间对脱硝性能影响不同,当温度偏差小于10%时脱硝效率主要受到反应温度的影响,而当温度偏差大于10%时温度偏差成为影响脱硝效率的主要因素;氨氮比主要影响氨逃逸率,当氨氮比由0.8增大到1.2时,氨逃逸率由0.55%增大到1.02%,而脱硝效率由42.5%增大到57.23%。     

城市固体废弃物与煤循环流化床混燃过程中N2O排放的实验研究

针对我国城市固体废物特征,在循环流化床装置上进行了城市固体放心弃物与煤混燃实验,研究了在混燃过程中城市固体废弃物与煤掺烧比例（R）及床层温度变化对N2O排放浓度的影响。实验结果显示,当开始加入垃圾时,N2O排放浓度迅速降低,随着掺烧比例的增加,其排放浓度不仅不进一步降低反而略有升高,当城市固体废弃物与煤掺烧比例R恒定时,随床温的增加,N2O排放浓度呈下降趋势。     

Integrating waste activated sludge (WAS) acidification with denitrification by adding nitrite (NO2−)

Adding nitrite (NO₂⁻) to waste activated sludge (WAS) fermentation systems is an efficient approach to integrate fermentation with denitrification, and utilize volatile fatty acids (VFAs) to achieve a high nitrogen removal rate even at low C/N ratios. In this study, the effect of nitrite on the integrated WAS fermentation and denitrification (termed as WASFD) was investigated under acidic and alkaline conditions. The results indicated that adding nitrite achieved a most reduction of nitrite to N₂ and improved the acidification of WAS with high VFAs production. Under acidic condition (pH = 5), the maximum VFAs produced with nitrite addition was 3.3 times that without nitrite addition. Higher concentration of free nitrous acid (FNA) at the pH of 5 increased WAS particulates, improved the hydrolysis of organic substrates, and finally promoted VFAs yields. Under alkaline condition (pH = 9), adding nitrite only increased the VFAs production by 1.5 times, indicating that acidic condition was preferable for acidification than alkaline condition.     

甲烷/丙烷在氧化铁表面还原NO的红外原位研究*

利用漫反射红外傅里叶变换光谱仪(DRIFTS)对甲烷/丙烷在氧化铁表面还原NO的反应进行了原位研究,分析了不同气体在氧化铁表面的吸附特点以及在有O_2条件下甲烷/丙烷还原NO的中间产物生成特性。结果表明,氧化铁对NO有着较好的吸附能力,NO能够以不同桥式硝酸盐与硝基的形式吸附于氧化铁表面。这些吸附物种热稳定性各不相同,并且可能会被氧化铁中的晶格氧氧化产生新的吸附物种,对进一步与还原剂发生选择性催化反应有着重要的作用。甲烷与丙烷在氧化铁表面还原NO的微观反应机理通过一系列路径完成。还原剂吸附于氧化铁表面,与由NO吸附形成的含氮吸附物种相互反应,形成一系列碳氢中间产物,通过进一步反应还原NO;在氧气存在的情况下,O_2会参与碳氢还原剂与含氮吸附物种的竞争反应,并形成R—COO-、CH3COO-等更多活性中间物种,这些活性中间物种通过与NO不断的反应最终还原NO为N2。     

The role of microbial electrogenesis in regulating methane and nitrous oxide emissions from constructed wetland-microbial fuel cell

This study assesses a sustainable solution to greenhouse gases (GHGs) mitigation using constructed wetland-microbial fuel cells (CW-MFC). Roots of wetland plant Acorus Calamus L. are placed in biological anode to better enable anode microorganisms to obtain rhizosphere secretion for power improvement. Three selected cathode materials have a large difference in GHG emissions, and among them, carbon fiber felt (CFF) shows the lowest emissions of methane and nitrous oxide, which are 0.77 ± 0.04 mg/(m²·h) and 130.78 ± 13.08 μg/(m²·h), respectively. The CFF CW-MFC achieves the maximum power density of 2.99 W/m³. As the influent pH value is adjusted from acidic to alkaline, the GHGs emissions are reduced. The addition of Ni inhibits GHGs emission but decreases the electricity, the power density is reduced to 1.09 W/m³, and the methane and nitrous oxide emission fluxes decline to 0.20 ± 0.04 mg/(m²·h) and 15.49 ± 1.86 μg/(m²·h), respectively. Low C/N ratio reduces methane emission, while high C/N ratio effectively inhibits nitrous oxide emission. At the influent pH 8 and C/N = 5:1, the methane emission flux is approximately 10.60 ± 0.27 mg/(m²·h), and the nitrous oxide emission flux is only 10.90 ± 1.10 μg/(m²·h). Based on the above experimental results by controlling variable factors, it is proposed that CW-MFC offers an environment-friendly solution to regulate GHG emissions.     

水蒸气对金属铁与丙烯还原NO的影响

实验研究了水蒸气对丙烯在金属铁作用下还原NO的影响。研究了陶瓷管流动反应器在300~1 100℃时不同条件下水蒸气对脱硝效率的影响,采用XRD对反应后铁样品表面的组分进行分析。结果表明,在N_2氛围条件下,水蒸气使NO的还原效率有所降低。在模拟烟气条件下,水蒸气使NO的还原效率增加,如ξ1=0.9,在1 000℃时,烟气中含有体积分数为7.00%的水蒸气时,NO的还原效率为93.0%,而无水蒸气时NO的还原效率为85.5%。在湿烟气条件SO_2对丙烯在金属铁表面还原NO的效率影响不大,可以忽略。在N_2氛围,有水蒸气时,丙烷在金属铁表面还原NO的效率高于丙烯。但在模拟烟气条件下,有水蒸气时,丙烯在富燃料条件下在金属铁表面还原NO的效率高于丙烷,在富氧条件下则相反。     

High performance biomass-derived catalysts for the oxygen reduction reaction with excellent methanol tolerance

The discovery of low cost and efficient catalytic materials for the oxygen reduction reaction (ORR) is of paramount importance for industrial-scale fuel cell manufacture. In this work, a convenient and straightforward approach was designed and applied to produce iron and nitrogen co-doped biomass carbon/graphene composite (Fe–N/C_B-RGO) by using soybean dregs combined with graphene oxide (GO). The results show that the optimized Fe–N/C_B-RGO (1) sample has high catalytic activity and stability for ORR, the onset potential of Fe–N/C_B-RGO (1) is 0.02 V vs. Hg/HgO, which is merely 50 mV negative-shifted comparison with commercial Pt/C. The composition optimized Fe–N/C_B-RGO (1) catalyst showed excellent methanol tolerance, with the presence of methanol surprisingly improving ORR performance. This unique catalytic performance of the Fe–N/C_B-RGO (1) catalyst is attributed to electron transfer synergies arising from close interfacial contact between the biomass-derived carbon and graphene.     

Noble-free oxygen reduction reaction catalyst supported on Sengon wood (Paraserianthes falcataria L.) derived reduced graphene oxide for fuel cell application

Reduced graphene oxide (RGO) has progressed as one of key emerging carbon for catalyst support material. As an alternative to the conventional RGO precursor, biomass Sengon wood was converted into RGO for use as a noble metal free catalyst support in oxygen reduction reaction (ORR). This work intends to reveal the applicability of Sengon wood-derived RGO in anchoring/doping iron and nitrogen particles onto its surface and to study its ORR performance in a half-cell environment. Thin-sheet layer and highly defective (I_D/I_G) was gradually obtained at elevated pyrolysis temperature of Sengon wood graphene oxide (GO) at range 700°C to 900°C. As prepared RGO was further doped into catalyst (Fe/N/RGO) through the same pyrolysis procedure at a selected temperature after mixing the GO powder with iron chloride and different nitrogen precursors (urea, choline chloride, and polyaniline) at a fixed ratio. The ORR activity reached a current density up to 2.43 mA/cm², which in conjunction with smooth multilayer sheet morphology and high graphitic-N content as the active sites. Stability analysis indicated an 85% current efficiency and only 0.03 V reduction in onset potential on methanol resistant test for Fe/ChoCl/RGO catalyst. This study revealed that Sengon wood-derived RGO successfully supported Fe-N-C catalyst which showed comparable oxygen reduction activity to Pt/C.     

玉米秸秆催化热解试验研究

利用自行设计的固定床快速热裂解试验系统,研究了玉米秸秆催化热解(催化剂为CaO)规律及催化剂对热裂解产物分布的影响,探讨了CaO的催化机理.结果表明,750℃时,CaO在促进焦油裂解的同时,也促进了焦炭和气体产物的生成;CaO对气体产物中的CO2具有吸附作用,降低了CO2的含量,它对大分子脱氢具有明显的催化选择性,增加了产气中H2的含量.在试验中采用了2种催化剂添加方式,添加比为1:1(质量比);分析了不同催化剂添加方式对催化热解的影响;采用悬挂方式时产气率达到57.68%;采用混合方式时,燃气中H2含量高达33.33%,燃气热值达到了12.389 MJ/m3.     

Catalytic steam gasification of Mengdong coal in the presence of iron ore for hydrogen-rich gas production

Hydrogen-rich gas production from catalytic steam gasification of coal was investigated in the presence of iron ore in a vertical fixed bed reactor. The addition of iron ore significantly promoted the H₂ yields. The effects of operation parameters (upper zone temperature, lower zone temperature, steam concentration, and iron to coal ratio) on the yield of selected gaseous products (H₂ and CO) during catalytic steam gasification, were studied using Taguchi method. The results of signal-to-noise ratio indicated that steam concentration and iron to coal ratio were the most important parameters in determining the yield of H₂ and CO, respectively. Semi-quantification X-ray diffraction analysis of iron ores indicated that increase in steam concentration intensified the oxidization of low valence iron compounds to Fe₃O₄. In addition, formation of Fe₃O₄ was also favored with increasing reaction temperatures (600 °C–900 °C). However, the formation of Fe₃O₄ was inhibited at higher reaction temperature (1000 °C) due to the destruction of porous structures of the iron ore.