液相共存成分对双极膜电解吸氨法脱碳富液的影响

考察了烟气中SO₂、NO_x和CO₂与NH₃·H₂O的反应机理以及双极膜电解吸的机理,对本文自制实验系统的操作工况进行了进一步的调整,探究了氨法脱碳吸收富液双极膜电解吸的一般规律,研究了模拟解吸液解吸过程中主要液相共存成分,如(NH₄)₂SO₃、(NH₄)₂SO₄、NH₄NO₃、NaCl和NH₄Cl对CO₂双极膜电解吸的影响。研究表明,液相共存成分种类、质量分数、pH、表面张力等对CO₂的双极膜电解吸均能产生一定影响。少量NaCl、NH₄Cl和(NH₄ )₂SO₄成分的共存对吸收富液的电解吸是有利的,且对电解吸的影响程度为NaCl> NH₄Cl> (NH₄)₂SO₄;吸收富液中应该极力避免(NH₄)₂SO₃成分的存在;NH₄NO₃成分的共存对脱碳富液电解吸的影响不大。因此,在碳捕集前应对烟气中的杂质成分进行脱除,减少其对解吸液理化特性以及双极膜电解吸的影响。     

Combustion synthesis of perovskite-type catalysts for natural gas combustion

Combustion synthesis has been applied to LaMnO₃ production with a view to boosting its activity towards natural gas combustion by enhancing its specific surface area. With a highly exothermic and self-sustaining reaction, this oxide can be quickly prepared from an aqueous solution of metal nitrates (oxidisers) and urea (fuel).

The favourable conditions for LaMnO₃ formation were sought: only fuel-rich mixtures are effective, but carbonaceous deposits are formed when too much urea is used. In the field of operating conditions in which the combustion synthesis reaction takes place, the specific surface areas were not dramatically higher than those obtained with traditional methods; moreover, even short thermal treatments have been found to rapidly deactivate the catalysts by rapid sintering. With a view to tackling these problems, NH₄NO₃ was chosen as an additive for its low costs, highly exothermic decomposition and because it generates gaseous products only, without altering the proportion of the other elements in the catalysts. With ammonium nitrate, specific area was enhanced from 4 m²/g up to about 20 m²/g. A short thermal treatment at 900 °C partially deactivates also the NH₄NO₃-derived catalysts. It was found that NH₄NO₃-boosted mixtures produce materials whose activity, after a similar thermal treatment, behave practically as the perovskites obtained by the “citrates” method.

Combustion synthesis is though rather cheap—in terms of reactants employed—and quick, given that the process requires few minutes at low temperature without successive calcination. However, the main drawback of this method is that hazardous or polluting compounds are emitted during the synthesis (mainly NH₃ or NO_x).

The MgO introduction, which should act both as a structural promoter and as a sulphur poisoning limiting agent, has proved to be harmful: since MgO does not physically interpose between perovskite grains, it does not offer resistance to deactivation induced by high temperatures.     

含硫酸亚铁废溶液的生物氧化过程中氮源对溶解性Fe（Ⅲ）生成量的影响

利用嗜酸性氧化亚铁硫杆菌将含硫酸亚铁废溶液中的Fe²⁺氧化成Fe³⁺后用于脱除H₂S,同时实现了含硫酸亚铁废溶液的循环利用和H₂S的脱除。而溶解性Fe³⁺较高的生成量是保证该处理系统连续高效运行的关键因素。但在充足氮源和K⁺条件下大量Fe³⁺以黄铁矾沉淀形式存在。因此,本文通过控制氮源种类及投加浓度,减少沉淀生成,增大溶解性Fe³⁺生成量,以期提高H₂S的去除效率。结果表明（NH₄）₂HPO₄可替代以往研究中的（NH₄）₂SO₄作为氮源,确定适宜菌体生长的氮源浓度范围为0.33～1 g·L^-1。在1 g·L^-1 （NH₄）₂HPO₄条件下细菌生长无明显停滞期、Fe²⁺平均氧化速率为0.221～0.229 g·（L·h） ^-1,Fe³⁺生成量为7.62～7.72 g·L^-1,沉淀量为1.17 g·L^-1,因此确定（NH₄）₂HPO₄为1 g·L^-1时最能保证H₂S的脱除效率。为降低工艺成本,最低可采用0.33 g·L^-1为运行浓度。该优化方案不仅保证了菌体的Fe²⁺氧化活性,而且有效地减少了菌体培养过程中沉淀的产生,获得了较高的Fe³⁺生成量和增速,为使用含硫酸亚铁废溶液处理H₂S的工艺条件优化提供了依据。     

热化学复合吸附储热循环的理论及实验

对一种基于固-气可逆化学反应的热化学复合吸附储热循环的储热特性以及能量品位提升性能进行了理论分析,并以MnCl₂/SrCl₂/NH₃作为工质对进行了实验研究。理论分析表明,热化学复合吸附储热循环不仅可以降低外界驱动热源的温度并保证输出热能温度稳定,而且能大幅度地提升输出热能的温度品位。在MnCl₂和SrCl₂都参与放热的实验工况下,获得的储热效率为93.31%。MnCl₂复合吸附剂的总储热密度按单位质量反应盐MnCl₂和单位质量的固化吸附剂计量分别为4393.36和3734.36 kJ·kg^-1;SrCl₂复合吸附剂的总储热密度按单位质量反应盐SrCl₂和单位质量的固化吸附剂计量分别为1947.28和1655.19 kJ·kg^-1。结果表明,热化学储热是一种相当有潜力的储热方式,可为低品位热能的高效回收利用提供强有力的技术支持。     

The role of H2O and NH3 on the formation of NH4NO3 aerosol particles and De-NOx under the corona discharge treatment of combustion flue gases

In this paper, mechanisms of NO_x removal by streamer corona discharges are proposed and the role played by H₂O and NH₃ in the system is discussed in detail. The results show that: (1) The ion-molecule reactions play an important role in the De-NO_x processes as well as the radicals reactions. (2) The effects of gas temperature and electron energy cannot be neglected in current processes. (3) The effect of H₂O and NH₃ concentrations and external electric field becomes a significant influence on the current processes due to the importance of the ion-molecule reactions and volume recombinations. (4) Ion induced aerosol formation plays an important role in the formation of NH₄NO₃ ultrafine particles.     

Fe-SAPO-44分子筛制备及催化脱硝性能

运用N2保护下的离子交换法制备Fe-SAPO-44分子筛催化剂,通过X射线粉末衍射(XRD)、N2吸附-脱附、电感耦合等离子体发射光谱仪(ICP-AES)、扫描电子显微镜(SEM)和氨气程序升温脱附(NH3-TPD)等研究Fe-SAPO-44催化剂的物化性质。对Fe-SAPO-44催化剂进行脱硝活性测试,考察其抗水热老化性能。结果表明,制备的Fe-SAPO-44催化剂的脱硝活性良好,并具有较好的抗水热老化能力。     

ZSM-35分子筛的酸改性及其用于丙烯水合制异丙醇反应的性能

采用水热合成法制备Na-ZSM-35分子筛。用不同浓度NH_4NO_3溶液对ZSM-35分子筛进行铵交换,不同焙烧温度下进行焙烧处理,制成H-ZSM-35分子筛。采用XRD、SEM、FT-IR和NH3-TPD对酸改性ZSM-35分子筛催化剂进行表征,并用于丙烯水合反应,考察其催化性能。结果表明,交换液浓度0.4 mol·L-1和450℃焙烧处理的ZSM-35分子筛催化剂的B酸中心最多,丙烯水合制异丙醇催化性能最佳。在丙烯水合制异丙醇反应中,反应产物异丙醇物质的量分数为15.96%,选择性为98.52%。     

非热等离子体强化TiO2催化尿素分解副产物水解性能的研究

尿素-选择性催化还原技术低温下运行时尿素分解不彻底,易形成缩二脲、三聚氰酸和三聚氰胺等副产物。本研究将TiO₂催化剂与介质阻挡放电等离子体相结合,在程序升温条件下考察了载气中有无O₂时引入等离子体前后TiO₂催化尿素分解副产物水解的性能。结果表明：TiO₂表面缩二脲、三聚氰酸和三聚氰胺分别在43~261℃、217~300℃和199~300℃水解生成NH₃和CO₂,载气中有无O₂对催化水解过程几乎无影响。引入等离子体后缩二脲、三聚氰酸和三聚氰胺水解所需温度显著降低,载气中无O₂时引入等离子体NH₃产率变化不大,副产物仅有少量N₂O和NO,有O₂时NH₃产率显著降低,且生成较多N₂O、NO、NO₂及少量NH₄NO₂和NH₄NO₃。未来需从优化放电条件和催化剂组成等方面解决引入等离子体导致副产物形成等问题。     

Effects of exogenous addition on soil mineralization and nitrification of typical wetlands in the Yellow River Basin

Taking Zoige Wetland (soil A) in the upper reaches of the Yellow River, Baotou Nanhai Wetland (soil B) in the middle reaches, and the Yellow River Delta Wetland (soil C) in the lower reaches as the research objects, NH₄NO₃ and glucose were used as external nitrogen and carbon sources, respectively, and a 28 d constant temperature cultivation method was used. The effects of exogenous addition on daily average carbon mineralization rate (C_average), net nitrogen mineralization rate (NN_min), and net nitrification rate (NN_nitri) of typical wetland soil in the Yellow River Basin were studied. The results show that wetland types have significant effects on soil carbon and nitrogen mineralization and nitrification rates, and differences in soil physical and chemical properties are the main influencing factors. Carbon addition significantly increased C_average of different wetland soils and the most significant promotion was exerted on soil A. However, nitrogen addition had no significant effect on C_average. Addition level had significant influence on NN_min. Low level carbon addition significantly inhibited NN_min of soil C while had no significant effect on that of soil A or soil B. High level carbon addition significantly prevented NN_min of different wetland soils. Low level nitrogen addition had no significant effect on NN_min. High level nitrogen addition significantly inhibited NN_min of soil B and soil C, while had no significant effect on soil A. Exogenous addition had no significant effect on NN_nitri.     

外源添加对黄河流域典型湿地土壤矿化及硝化的影响

以黄河上游若尔盖湿地(A土)、中游包头南海湿地(B土)、下游黄河三角洲湿地(C土)为研究对象,分别选用NH4NO3和葡萄糖作为外加氮源和碳源,采用28 d恒温培养法,研究了外源添加对黄河流域典型湿地土壤日平均碳矿化速率(Caverage)、净氮矿化速率(NNmin)、净硝化速率(NNnitri)的影响。结果表明,湿地类型对土壤碳、氮矿化及硝化速率影响显著,土壤理化性质差异是主要影响因素。外源碳添加对不同类型湿地Caverage均显著提高,且对A土促进作用最显著;外源氮添加对Caverage影响不显著。外源碳、氮添加水平对不同类型湿地NNmin的影响存在显著差异。低水平碳源添加显著抑制C土NNmin,但对A土和B土NNmin影响不显著;高水平碳源添加对不同类型湿地NNmin均表现出显著的抑制作用。低水平氮源添加对不同类型湿地NNmin影响不显著;高氮添加显著抑制B土、C土NNmin,但对A土NNmin影响不显著。外源碳、氮添加对不同类型湿地NNnitri的影响不显著。     

Conductivity of molten hydrated salts: Mg(NO3)2. 6H2O + NH4NO3 system

Conductivity of molten Mg(NO₃)₂. 6H₂O + NH₄NO₃ system containing up to 80 mole percent of the latter was measured in the temperature range 320–400 K. Temperature dependence of conductivity exhibited Arrhenian behaviour. Conductivity—composition isotherms were non-linear indicating weak ordering tendencies. Equivalent conductivity data did not obey Markov equation; deviations have been interpreted in terms of the Tobolsky parameter (θ). Constancy of θ indicate that the water of hydration in the system remains with Mg²⁺ ions and is unaffected by the addition of NH⁺₄ ions.     

多级结构羟基硝酸铜纳米酶的制备及其对酚类污染物的降解

漆酶是一种多铜氧化酶,在空气条件下即可催化氧化多胺、多酚类有机物,被认为是水处理及土壤修复领域的绿色催化剂。纳米酶是一种具有酶催化活性的纳米材料,因其具有多功能性、低成本、高稳定性等优点,近年来引起广泛关注。因此,本文以尿素水解过程中产生的异氰酸根离子为模板剂,与Cu(NO₃)₂溶液反应制备具有漆酶活性的多级结构羟基硝酸铜[H-Cu₂(OH)₃NO₃]纳米酶。其催化活性是传统Cu(NO₃)₂与尿素水解法制备的羟基硝酸铜的1.85倍,其最大反应速率是漆酶的1.27倍。H-Cu₂(OH)₃NO₃纳米酶在不同pH、温度、储存时间和盐浓度条件下体现良好的催化稳定性。在重复利用12次后,保持58%的催化活性,体现出良好的重复利用性。而且H-Cu₂(OH)₃NO₃纳米酶具有降解土壤与地下水中常见的2,4-二氯苯酚、对...     

柠檬酸工业废水强化镉污染土壤的电化学法修复

通过批量解吸附实验和电化学修复实验,研究利用柠檬酸工业废水作为电化学修复的增效剂从高缓冲容量的天然土壤中去除镉的可行性。批量实验结果表明,当加入柠檬酸工业废水时,85%以上的镉能在土壤pH≤5.0的条件下从土壤中溶解到溶液中;在pH5.0～8.0范围内镉的解吸附率比用去离子水增加20%～45%。电化学修复实验结果表明,与相同pH值的HNO₃相比,该废水作为电极溶液可使镉在土壤中发生明显迁移;在距离阳极0～4 cm及8～10 cm处土壤镉含量由282 mg·kg^-1降低至167～200 mg·kg^-1,而在距阳极4～8 cm处土壤镉含量升高至约400 mg·kg^-1。经过514 h的电化学修复,约84.7%的镉可以从土壤中去除,其中约94.6%从土壤中去除的镉富集在阴极溶液中。可见柠檬酸工业废水是一种非常有前景的重金属污染土壤电化学修复增效剂。     

并流沉淀法合成Fe掺杂ZnO及其光催化脱氮性能

以Zn（NO₃）₂·6H₂O与NH₃·H₂O为原料,采用并流沉淀法合成了Fe掺杂ZnO,通过X射线衍射（XRD）、场发射扫描电镜（FE-SEM）、透射电子显微镜（TEM）、紫外可见漫反射（UV-vis DRS）及比表面积（BET）等测试方法对产物的结构与形貌进行了表征;并以吡啶（Py）石油醚溶液为模拟污染物,考察了其光催化脱氮性能。结果表明,当Fe掺杂量不高于1.0%时,所有复合物均拥有单一的六方晶系纤锌矿结构,尚未出现其他物相。Fe掺杂可有效抑制ZnO晶粒的生长,增大产品的比表面积,并拓宽其光响应范围,显著提高催化剂的光催化活性。处理初始浓度为10 μg·g^-1的Py石油醚溶液,0.50% Fe光催化剂投加量为0.6 g·L^-1,光照距离10 cm,经150 W高压汞灯照射50 min,Py的降解率达到65.3%。     

Electrochemical behaviour of chromium, molybdenum and manganese in liquid ammonia

Steady state polarization of Cr, Mn and Mo were measured in liquid ammonia with NH₄NO₃ and NH₄Cl at 0°C and 20°C. Cr amd Mo can corrode in the active and passive states. Mn remains active, but a porous film is deposited after prolonged dissolution. From the Tafel slopes it is concluded that the metals are oxidized to divalent ions during active dissolution.     

The importance of Fe loading on the N2O reduction with NH3 over Fe-MFI: Effect of acid site formation on Fe species

Effect of the loading amount of Fe over ion-exchanged Fe-MFI catalysts on the catalytic performance of N₂O reduction with NH₃ was investigated, and the results indicated that the turnover frequency (TOF) was almost constant in the Fe/Al range between 0.05 and 0.40. The activity of N₂O + NH₃ reaction was much lower than that of N₂O + CH₄ reaction over Fe-MFI (Fe/Al = 0.40), and the preadsorption of NH₃ decreased drastically the activity of N₂O + CH₄ reaction. The temperature-programmed desorption (TPD) of NH₃ showed the formation of stronger acid sites on Fe-MFI (Fe/Al = 0.24 and 0.40), and the amount of the acid sites agrees well with the desorption amount O₂ in O₂-TPD in the low temperature range. The acid sites gave a 3610 cm⁻¹ peak (Brønsted acid) in FTIR observation. These results suggest that the acid sites were formed on the bridge oxide ions in binuclear Fe species. Adsorbed NH₃ on the strong acid sites inhibited N₂O dissociation, which can be related to the low activity of N₂O + NH₃ reaction over Fe-MFI with high Fe loading.     

Insight into SO2 poisoning and regeneration of one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NOx by NH3

The effects of SO₂ on an one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NO_x by NH₃ were examined. The addition of SO₂ inhibited NO_x conversion significantly below 300 ℃, while no effect on NO_x conversion was observed above 300 ℃. TGA, TPD, and XPS results showed that the deactivation was caused by the formation of (NH₄)₂SO₄, SO₂ chemisorption on the isolated Cu²⁺ ion sites, as well as the formation of CuSO₄-like species. Among them, the site-blocking effect of (NH₄)₂SO₄ on Cu²⁺ was the primary reason for deactivation. Fortunately, 89% of deNO_x activity of the poisoned catalyst was recovered after thermal treatment at 500 ℃ in air, where (NH₄)₂SO₄ was completely decomposed. The activity was further recovered with regeneration temperature increasing to 600 ℃, removing the adsorbed SO₂ on the Cu²⁺ sites. The regeneration at 600 ℃ could not recover the activity completely, because of the high stability of CuSO₄-like species.     

前驱体结构对多环芳烃选择性开环Pt/Beta催化剂的影响

以海绵铂为原料合成出［Pt（NH₃）₆］Cl₄络合物,采用热重分析（TG）、扫描电镜-能谱（SEM-EDS）、紫外-可见分光光度计（UV-Vis）、质谱（MS）、X射线光电子能谱（XPS）等手段确定了［Pt（NH₃）₆］Cl₄的结构组成;以H₂PtCl₆、Pt（NH₃）₄Cl₂和［Pt（NH₃）₆］Cl₄为前驱体,采用等体积浸渍法制得Pt/Beta催化剂,采用X射线衍射（XRD）、X射线荧光光谱（XRF）、氨程序升温脱附（NH₃-TPD）、氢氧滴定（H₂-O₂）、透射电镜（TEM）、氢气程序升温脱附（H₂-TPD）等表征了Pt/Beta催化剂的物化性质,并考察了Pt/Beta催化剂的多环芳烃选择性开环性能。结果表明,［Pt（NH₃）₆］Cl₄络合物具有更高的“抗自还原”能力,可从前驱体结构上降低铂氨前驱体受热分解时的自还原现象。前驱体结构对铂纳米颗粒的几何尺寸及分布有较大影响,一方面络合物的价态显著影响前驱体与分子筛间的静电作用,进而影响铂纳米颗粒的落位与尺寸;另一方面络合物的空间结构影响前驱体在分子筛微孔中的分布,影响铂纳米颗粒的Ostwald熟化速率。前驱体结构可调变Pt/Beta催化剂的双功能匹配关系,显著影响Pt/Beta催化剂转化甲基萘的活性、稳定性,采用［Pt（NH₃）₆］Cl₄前驱体制备的Pt/Beta催化剂具有更优的活性及长周期稳定性。     

原位固氮剂在污泥堆肥过程中保氮机制

高温好氧堆肥技术虽然可有效处理有机固体废物,但常常会释放大量的氨气和造成氮素损失。本文以硫酸镁、磷酸二氢钾、硫酸镁+磷酸二氢钾（分别记为MgSO₄、KP和KPM处理组）为原位固氮剂,污泥和木屑为原料,进行高温好氧堆肥试验,研究以上原位固氮剂对污泥堆肥过程中的氨气挥发和氮素损失的影响。结果表明,硫酸镁（MgSO₄）对物料pH有显著的降低效应,添加硫酸镁使堆体高温期pH降低至8.17,低于硫酸镁+磷酸二氢钾（KPM）组（8.55）和对照（CK）组（8.90）。与CK相比,MgSO₄和KPM的NH₃累积释放量分别降低了34%和28%,反而KP组增加了35%。对比不同条件下XRD图谱可知,MgSO₄的固氮效应并不是由于MgNH₄PO₄·6H₂O的生成,而是由于其对pH的降低效应造成的。堆肥结束后,除了KP组,各处理条件下的种子发芽率值（germination index,GI）均不会对后续使用带来不利影响。     

利用κ-Köhler理论研究大气气溶胶的吸湿特性

利用κ-K?hler理论对西安、北京两地大气气溶胶体系的吸湿特性进行研究。选取多种代表性无机物（硫酸盐、硝酸盐、氯盐）及有机物（烯烃、芳香烃、羧酸）建立气溶胶体系模型，使研究体系更接近于真实大气成分。结果表明，在空气质量由清洁状态向雾霾发生状态转变的过程中，两种体系中均呈现有机物含量逐渐减少而(NH₄)₂SO₄和NH₄NO₃含量逐渐增多的趋势，这种变化趋势总是促使气溶胶体系整体吸湿能力增强，因此更易吸湿增长形成雾霾。对体系中不同组分对吸湿性的影响进行了定量预测，理论预测的变动趋势与实际观测的变动趋势相同，揭示了雾霾形成过程中各组分的变动趋势及影响程度，为针对性解决雾霾问题提供思路。