CuO改性商用选择性催化还原催化剂催化氧化单质汞性能

燃煤烟气中单质汞（Hg⁰）的高效氧化是提高燃煤电厂脱汞效率的关键,为提高传统选择性催化还原（SCR）催化剂氧化Hg⁰的性能,本文采用溶液浸渍法制备了CuO-SCR催化剂,在固定床反应装置上考察了其脱硝协同氧化单质汞性能,并借助BET、XRD和XPS等分析技术对催化剂进行表征。结果表明,CuO的掺杂显著提高了商用SCR催化剂的Hg⁰氧化性能和低温脱硝活性;在200~400℃内,随着反应温度升高和NO+NH₃浓度增大,NH₃对CuO-SCR催化剂的Hg⁰氧化性能抑制作用加强;在350℃、模拟燃煤烟气条件下,随着空速比的减小,催化剂的Hg⁰氧化性能显著提高,NH₃对Hg⁰氧化的抑制作用明显减弱。催化剂表征结果表明,CuO-SCR催化剂表面存在氧化还原反应V⁴⁺+Cu²⁺?V⁵⁺+Cu⁺,增强了催化剂的催化活性。Hg⁰在CuO-SCR催化剂表面的氧化过程遵循Mars-Maessen机制,能够有效增强催化剂的Hg⁰氧化性能。     

Fe3O4协同H2O2气相高级氧化单质汞的机理

利用密度泛函理论分别研究了H₂O₂分子在Fe₃O₄（111）、（110）和（001）表面分解特性,并对单质汞在H₂O₂/Fe₃O₄体系的反应特性进行了研究。对比不同构型的结合能、Mulliken电荷转移和分态密度分析,详细讨论了H₂O₂分解产生羟基的规律以及Hg⁰的氧化态中间产物成键特性。结果表明：H₂O₂分子在Fe₃O₄（111）、（001） A和（110） A表面更容易分解产生羟基;不同表面产生的羟基对Hg⁰具有不同的氧化活性;Hg⁰在表面羟基的作用下可有效通过电荷转移实现氧化。对比分析了三种表面汞氧化态中间产物的脱附路径,HO-Hg-OH和Hg-OH的表面脱附是主要的反应路径。     

烟气及飞灰组分对溴改性飞灰脱汞特性的影响

燃煤飞灰中的未燃碳（unburned carbon,UBC）和金属氧化物因对汞有一定的吸附和氧化作用而被认为是燃煤电厂廉价的潜在脱汞吸附剂,但效率有待提高。文章选取两种UBC含量不同的飞灰,采用质量分数1%的NH₄Br溶液对其浸渍改性,利用固定床汞吸附实验台探究了烟气组分（O₂、SO₂和NO）以及飞灰中无机金属氧化物对汞吸附和氧化的影响,以期获得高效脱汞吸附剂吸附机理。结果表明,O₂对于溴素改性飞灰氧化汞有较小的促进效果,SO₂具有一定的抑制作用,NO促进Hg⁰的氧化效果明显;溴素改性飞灰中的Fe₂O₃和TiO₂对Hg⁰的氧化起着主要作用,原因在于溴素改性增加了金属氧化物Fe₂O₃和TiO₂中的晶格氧含量,促进了Hg⁰的催化氧化,主要遵循Mars-Maessen机理。另外,UBC含量对飞灰脱除Hg⁰的影响很大,溴素嵌入飞灰表面的UBC时,会使其邻域的活性加强,从而增强碳质表面对Hg⁰的吸附能力,促进了后续反应的进行。     

CeO2/TiO2吸附剂煤气脱汞产物的浸出规律

基于金属氧化物脱汞吸附剂后续无害化处理要求，本文提出采用硫代硫酸钠(Na₂S₂O₃)溶液浸出金属氧化物脱汞产物的新思路。CeO₂/TiO₂吸附剂(CeTi)吸附汞后得到含汞吸附剂(Hg-CeTi)，利用汞程序升温脱附实验(Hg-TPD)确定其表面吸附态汞的赋存形态。随后探究Na₂S₂O₃溶液对于Hg-CeTi表面脱汞产物的浸出能力，着重分析不同赋存形态的汞在Na₂S₂O₃溶液中的迁移规律。Hg-TPD结果表明，模拟煤气中脱汞产物以HgCl₂、HgO和HgS为主。由于硫代硫酸根(S₂O₃^2-)与Hg²⁺的配合能力，HgO易从Hg-CeTi表面脱附并向液相迁移；HgCl₂会在液相中与OH^-反应生成Hg...     

煅烧温度对Mo-Mn/TiO2催化剂脱硝脱汞活性的影响

研究了浸渍法制备Mo-Mn/TiO₂（MMT）催化剂过程中煅烧温度（300℃、450℃、600℃、750℃）对Mo-Mn/TiO₂（MMT）催化剂协同脱硝脱汞活性的影响。结果表明,较低的煅烧温度更有利于MMT催化剂的协同脱硝脱汞性能,同时可有效降低SO₂对催化剂活性的抑制作用,最佳煅烧温度为300℃。利用BET、XRD、H₂-TPR、FTIR和XPS等表征手段对催化剂的理化性质进行了表征,结果表明较低的煅烧温度有利于提高催化剂中活性成分所占的比例,增加金属氧化物在TiO₂载体表面的分散度,提高催化剂的低温还原性能。随着煅烧温度的升高,催化剂的比表面积和孔容均逐渐减小,平均孔径先增大后减小,且在高温下发生烧结;MnO₂逐渐向Mn₂O₃转变,锐钛矿型TiO₂逐渐向金红石型转变,同时MoO₃由非晶态逐渐向晶态的转化,致使催化剂的协同脱硝脱汞活性下降。     

Fe2O3对V2O5-WO3/TiO2催化剂表面性质及其性能的影响

催化剂是选择性催化还原(SCR)脱硝技术的核心,研究Fe对钒钛系SCR催化剂脱硝活性及SO₂/SO₃转化率的影响具有重要意义。采用等体积浸渍法制备了不同Fe/V质量比的Fe₂O₃-V₂O₅-WO₃/TiO₂催化剂,并进行表征,研究Fe对钒钛系SCR催化剂脱硝活性及SO₂/SO₃转化率的影响,并讨论Fe对于钒钛系SCR催化剂表面性质的影响。结果表明,随着催化剂表面Fe₂O₃含量增加,催化剂的脱硝效率及二氧化硫氧化率均是先上升后下降,当Fe/V质量比为3.0时,催化剂的脱硝效率和二氧化硫氧化率均达到最大值91.78%、1.01%。XPS及H₂-TPR结果表明,随着Fe₂O₃含量增加,催化剂表面钒活性组分的相对含量及V⁴⁺/V⁵⁺比减小,催化剂表面吸附氧(O_α)浓度增加,催化剂的氧化能力增强。NO-TPD结果表明,随着Fe₂O₃含量增加,催化剂表面吸附NO的能力增强。     

一维TiO2-Al2O3载体的制备及其在加氢脱氮中的应用

为提高现有负载型NiMoS催化剂的加氢活性,以碳纳米管为结构导向剂,分别采用浸渍法和溶胶-凝胶法制备了2种一维TiO₂-Al₂O₃载体,并采用共浸渍法制备了相应的负载型NiMoS催化剂,探究了不同结构的载体对NiMoS/TiO₂-Al₂O₃催化剂加氢脱氮性能的影响。结果表明,当选择以溶胶-凝胶法制备的一维TiO₂-Al₂O₃为载体时,NiMoS/TiO₂-Al₂O₃催化剂上的加氢脱氮活性较高,在350℃、氢压为3 MPa、转速为400 r/min的条件下反应4 h,喹啉的转化率达到99%以上,脱氮率达到40.75%。     

水热处理和钨添加对低钒催化剂高温脱硝性能的影响

利用真空过量浸渍法在TiO₂和WO₃-TiO₂载体上负载0.5%钒（质量分数）制备了V₂O₅-TiO₂ （VTi）和V₂O₅/WO₃-TiO₂（VWTi）催化剂，并在含有10%（体积分数）水蒸气的空气氛下750℃水热处理24h得到处理态的VTi-A和VWTi-A催化剂。研究了水热老化和钨掺杂对催化剂脱硝效率的影响，并通过XRD、TEM、NH₃-TPD、H₂-TPR、XPS和Raman等表征方法对催化剂的结构和表面特性进行了表征分析。研究表明，水热处理和钨的协同作用使催化剂中产生更多的聚合态VO_x和低价态钒（V⁴⁺+V³⁺）。这两类活性物质所含有的氧物种具有较强SCR反应活性，可改善VWTi催化剂的高温脱硝性能，即使在酸性位数量减少的情况下仍有提升，这是低钒含量催化剂可满足燃气机组高温脱硝需求的主要原因。     

SO2活化改性石油焦吸附剂的汞吸附特性

利用SO₂气体对石化工业副产物石油焦进行活化改性以制成富硫高活性脱汞吸附剂（SAPC）。在固定床实验装置上进行SAPC吸附脱除汞的实验研究,考察吸附温度、入口Hg⁰浓度、烟气成分以及热再生等因素对脱汞特性的影响规律,同时结合比表面积及孔隙度分析、元素分析和X射线光电子能谱（XPS）等表征手段深入分析SAPC的汞吸附机理。结果表明,SO₂活化改性石油焦的物理和化学特性得到极大改善,羰基、酯基以及非氧化态硫是Hg⁰的主要活性吸附位。吸附温度的升高会抑制对Hg⁰的吸附脱除,烟气中较高的Hg⁰浓度会降低汞脱除效率,但对其汞吸附速率有促进作用。SO₂对SAPC的脱汞性能影响较小,O₂易将Hg⁰氧化成为更容易与含氧、含硫官能团结合的氧化态汞,从而促进对Hg⁰的脱除。热再生时吸附态汞化合物受热分解的过程伴随着吸附剂表面化学活性位的损失,导致再生后汞吸附性能大幅下降。     

CeO2改性再生SCR催化剂的单质汞氧化特性

对国内某1000MW燃煤发电机组失活选择性催化还原（SCR）催化剂进行CeO₂改性再生。对再生前后样品进行N₂吸附-脱附、扫描电子显微镜（SEM）、X射线荧光光谱（XRF）、傅里叶变换红外光谱（FTIR）对比表征分析。在自制固定床反应系统上对CeO₂改性再生催化剂（CeReCat）进行Hg⁰氧化性能测试,同时研究了SO₂、H₂O、NO和NH₃对Hg⁰氧化性能的影响。结果表明,CeO₂改性再生方法可有效清洗失活SCR催化剂表面杂质,恢复催化剂表面活性位点和孔隙结构,可使Ce、V两种活性元素得到有效负载。CeO₂改性后的样品Hg⁰氧化性能显著提升,3.0 CeReCat具有最佳Hg⁰的氧化效率。此外,烟气中加入600μL/L SO₂后,3.0 CeReCat仍具有高达74.4%的Hg⁰氧化效率,抗SO₂性能较好。烟气中的NO可轻微促进Hg⁰的氧化。由于竞争吸附作用,烟气中的H₂O和NH₃会抑制Hg⁰的氧化。CeO₂改性再生催化剂置于SCR系统下层时,由于烟气NH₃浓度较低而具有较高Hg⁰氧化效率,具有良好的应用前景。     

CO_2 methanation over TiO_2–Al_2O_3 binary oxides supported Ru catalysts

TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.     

NOx adsorption on MnO2/NaY composite: an in situ FTIR and EPR study

The NO, NO/O₂, and NO/O₂/H₂O adsorption on MnO₂/NaY (5 and 15 wt.% MnO₂) composite catalyst and NaY has been studied by means of in situ FTIR and EPR spectroscopy at elevated temperatures and during heating under reaction-like conditions. NO adsorption and co-adsorption of NO and O₂ on NaY and MnO₂/NaY proceeds via oxidation of NO forming NO₂⁻ and NO₃⁻ species. Whereas the manganese dioxide preferably acts as oxidising agent, the zeolite stores the NO_x species as nitrite and nitrate ions in the solid. In the presence of oxygen, the nitrate formation is enhanced due to additional oxidation of NO through gaseous oxygen leading to NO₂. Dimerisation of NO₂ to N₂O₄ and following disproportionation of the latter causes the formation of NO⁺ and NO₃⁻ species which are associated with nucleophilic zeolitic oxygen and especially alkali cations of the zeolite, respectively. The presence of oxygen facilitates reoxidation of Mn²⁺ which keeps more Mn ions in the active state. Pre-adsorbed water and higher amounts of water vapour in the feed hinder the NO adsorption by blocking the adsorption sites and shift the nitrate formation to higher temperatures. The quantities and thermal stability of the nitrates formed during NO and NO/O₂ adsorption differs which points to a different mechanism of nitrate formation. In the absence of gaseous oxygen, nitrates are formed by participation of only lattice oxygen. In the presence of oxygen, nitrate formation by dimerisation and disproportionation reactions of NO₂ dominates. The manganese component of the composite catalyst supports the oxidation of NO to nitrite and subsequently to nitrate. During this process Mn⁴⁺ is reduced to Mn²⁺ as evidenced by in situ EPR measurements.     

Controllable synthesis of novel nanoporous manganese oxide catalysts for the direct synthesis of imines from alcohols and amines

A novel template-free oxalate route was applied to synthesize different mesoporous manganese oxides (amorphous manganese oxide (AMO), Mn₅O₈, Mn₃O₄, MnO₂) in the narrow temperature range from 350℃ to 400℃ by controlling the calcination conditions, which were employed as the efficient catalysts for the oxidative coupling of alcohols with amines to imines. The chemical and structural properties of the manganese oxides were characterized by the methods of thermogravimetry analysis and heat flow (TG-DSC), X-ray diffraction (XRD), nitrogen sorption, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR), and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The structures of different manganese oxides were confirmed by characterization. The M-350 (AMO) presented the maximum surface area, amorphous nature, the lowest reduction temperature, the higher (Mn³⁺ + Mn⁴⁺)/Mn²⁺ ratio, and the higher adsorbed oxygen species compared to other samples. Among the catalysts, M-350 showed the best catalytic performance using air as an oxidant, and the conversion of benzyl alcohol (BA) and the selectivity of N-benzylideneaniline (NBA) reached as high as 100% and 97.1% respectively at the lower reaction temperature (80℃) for 1 h. M-350 had also the highest TOF value (0.0100 mmol·mg^-1·h^-1) compared to the other manganese oxide catalysts. The catalyst was reusable and gave 95.8% conversion after 5 reuse tests, the XRD pattern of the reactivated M-350 did not show any obvious change. Lattice oxygen mobility and (Mn³⁺ + Mn⁴⁺)/Mn²⁺ ratio were found to play the important roles in the catalytic activity of aerobic reactions.     

Zeolite-mediated removal of NOx by NH3 from exhaust streams at low temperatures

NH₃ stored on zeolites in the form of NH₄⁺ ions easily reacts with NO to N₂ in the presence of O₂ at temperatures <373 K under dry conditions. Wet conditions require a modification of the catalyst system. It is shown that MnO₂ deposited on the external surface of zeolite Y by precipitation considerably enhances the NO_x conversion by zeolite fixed NH₄⁺ ions in the presence of water at 400–430 K. Particle-size analysis, temperature-programmed reduction, textural characterization, chemical analysis, ESR and XRD gave a subtle picture of the MnO₂ phase structure. The MnO₂ is a non-stoichiometric, amorphous phase that contains minor amounts of Mn²⁺ ions. It loses O₂ upon inert heating up to 873 K, but does not crystallize or sinter. The phase is reducible by H₂ in two stages via intermediate formation of Mn₃O₄. The manufacture of extrudates preserving stored NH₄⁺ ions for NO_x reduction is described. It was found that MnO₂ can oxidize NO by bulk oxygen. This enables the reduction of NO to N₂ by the zeolitic NH₄⁺ ions without gas-phase oxygen for limited time periods. The composite catalyst retains storage capacity for both, oxygen and NH₄⁺ ions despite the presence of moisture and allows short-term reduction of NO without gaseous O₂ or additional reductants. The catalyst is likewise suitable for steady-state DeNO_x operation at higher space velocities if gaseous NH₃ is permanently supplied.     

Ti-modified alumina supports prepared by sol–gel method used for deep HDS catalysts

The typical physico-chemical properties and their hydrodesulfurization activities of NiMo/TiO₂-Al₂O₃ series catalysts with different TiO₂ loadings were studied. The catalysts were evaluated with a blend of two kinds of commercially available diesels in a micro-reactor unit. Many techniques including N₂-adsorption, UV–vis DRS, XRD, FT-Raman, TPR, pyridine FT-IR and DRIFT were used to characterize the surface and structural properties of TiO₂-Al₂O₃ binary oxide supports and the NiMo/TiO₂-Al₂O₃ catalysts. The samples prepared by sol–gel method possessed large specific surface areas, pore volumes and large average pore sizes that were suitable for the high dispersion of nickel and molybdenum active components. UV–vis DRS, XRD and FT-Raman results indicated that the presence of anatase TiO₂ species facilitated the formation of coordinatively unsaturated sites (CUS) or sulfur vacancies, and also promoted high dispersion of Mo active phase on the catalyst surfaces. DRIFT spectra of NO adsorbed on the pure MoS₂ and the catalysts with TiO₂ loadings of 15 and 30% showed that NiMo/TiO₂-Al₂O₃ catalysts possessed more CUS than that of pure MoS₂. HDS efficiencies and the above characterization results confirmed that the incorporation of TiO₂ into Al₂O₃ could adjust the interaction between support and active metals, enhanced the reducibility of molybdenum and thus resulted in the high activity of HDS reaction.     

Photodegradation catalyst screening by combinatorial methodology

In this work, a combinatorial methodology was developed for photodegradation catalyst screening. A fluorescence imaging detection system was designed for high throughput analysis, 1,6-hexamethylenediamine was used as the probe molecule for catalyst testing. The photodegradation activity of catalysts was evaluated by 1,6-hexamethylenediamine consumption during the photodegradation reaction. The methodology could provide reliable results. We found that pure TiO₂, ZrO₂, Nb₂O₅, MoO₃, and WO₃ did not show much activity for 1,6-hexamethylenediamine photodegradation under visible light. TiO₂ catalysts doped with different metal ions were tested. When TiO₂ was doped with Ta₂O₅, Nb₂O₅, V₂O₅, MoO₃, or WO₃, higher activity for photodegradation was observed. The doping of La³⁺, Ba²⁺, and Br⁻ to TiO₂ did not improve the catalytic activities. When doping TiO₂ with Mn²⁺, Cl⁻, Al³⁺, Cu²⁺, Fe³⁺, Na⁺, Mg²⁺, Li⁺, F⁻, Co²⁺, or K⁺, catalytic activity was lower than that of pure TiO₂. After elaborate catalysts screening, we discovered new catalysts, such as 50–70% TiO₂/0–20% WO₃/20–40% VO_2.5 and 20–30% TiO₂/30–50% MoO₃/40–60% VO_2.5 as well as 30% WO₃/20% ZrO₂/50% NbO_2.5 (synthesized from ZrCl₄, NbCl₅, and (NH₄)₅H₅[H₂(WO₄)₆]·H₂O in ethanol solution or suspension) and 60–70% WO₃/Nb₂O₅ (synthesized from WCl₆ and NbCl₅ in ethanol solution). We observed that the catalytic activity is sensitive to preparation methods and catalyst specific surface areas. When P123 (HO(CH₂CH₂O)₂₀(CH₂CH(CH₃)O)₇₀(CH₂CH₂O)₂₀H, designated EO₂₀PO₇₀EO₂₀) was used as template to synthesize mesoporous materials, the mesoporous catalysts showed higher activity than regular catalytic materials.     

Co3O4 with ordered pore structure derived from wood vessels for efficient Hg0 oxidation

Catalytic oxidation of Hg⁰ to HgO is an efficient way to remove Hg⁰ from coal-fired flue gas. The catalyst with ordered pore structure can lower mass transfer resistance resulting in higher Hg⁰ oxidation efficiency. Therefore, in the present work, wood vessels were used as sacrificial template to obtain Co₃O₄ with ordered pore structure. SEM and BET results show that, when the mass concentrations of Co(NO₃)₂·6H₂O was 20%, the obtained catalyst (Co₃O₄ [20%Co(NO₃)₂]) possesses better pore structure and higher surface area. It will expose more available surface active sites and lower the mass transfer resistance. Furthermore, XPS results prove that Co₃O₄ [20%Co(NO₃)₂] has the highest ratio of chemisorbed oxygen which plays an important role in Hg⁰ oxidation process. These results lead to a better Hg⁰ oxidation efficiency of Co₃O₄ [20%Co(NO₃)₂], which is about 90% in the temperature range of 200 to 350 ℃. Furthermore, Co₃O₄ [20%Co(NO₃)₂] has a stable catalytic activity, and its Hg⁰ oxidation efficiency maintains above 90% at 250 ℃ even after 90 h test. A probable reaction mechanism is deduced by the XPS results of the fresh, used and regenerated catalyst of Co₃O₄ [20%Co(NO₃)₂]. Chemisorbed oxygen can react with Hg⁰ forming HgO with the reduction of Co³⁺ to Co²⁺. And lattice oxygen and gaseous oxygen can supplement the consumption of chemisorbed oxygen to oxidize Co²⁺ to Co³⁺.     

焙烧及还原条件对Ni2P/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用溶胶-凝胶法制备了TiO₂-Al₂O₃复合载体, 以柠檬酸(CA)为络合剂采用浸渍法制备了Ni₂P负载的TiO₂-Al₂O₃复合载体催化剂, 并用 X 射线衍射(XRD)、N₂吸附比表面积(BET)测定技术对催化剂的结构和性质进行了表征, 考察了载体焙烧温度、催化剂焙烧温度、还原温度、还原压力对其进行的二苯并噻吩(DBT)加氢脱硫(HDS)性能的影响。结果表明, 升高载体焙烧温度有利于催化剂表面上活性物种的分散, 但焙烧温度过高会导致催化剂烧结, 适宜的载体焙烧温度为550℃。当还原温度为500～550℃时, 磷化镍主要以Ni₁₂P₅相形式存在, 且随着还原温度的升高, Ni₁₂P₅的衍射峰强度逐渐增强, 还原温度为700℃时, 可得到单一的Ni₂P物相。载体焙烧温度为550℃, 催化剂焙烧温度为500℃, 还原温度为700℃, 常压还原制备的Ni₂P/TiO₂-Al₂O₃催化剂具有最好的活性。在360℃、3.0MPa、氢油体积比500、液时体积空速2.0h^-1的条件下, 反应4h时, DBT转化率为99.5 %。     

Preparation and characterization of lithium λ-MnO2 ion-sieves

Lithium λ-MnO₂ ion-sieves were prepared from spinel LiMn₂O₄ via treatment with nitric acid. The LiMn₂O₄ was synthesized by a solid state reaction between LiOH·H₂O and MnO₂. The effects of the calcination time and temperature on the preparation of the LiMn₂O₄ precursor and the lithium ion-sieve were investigated. In addition, the Li⁺ extraction ratio, the Mn²⁺ dissolving ratio and the adsorption properties of the lithium ion-sieve were all measured. The lithium ion-sieve had a high exchange capacity and was selective for Li⁺. Specifically, at pH= 13, the ion exchange capacity of Li⁺ was 30.9 mg/g in 10 mmol/L LiCl solution and the lithium extraction ratio and manganese dissolving ratio were 95% and 25%, respectively.