Correlations between acidity, surface structure, and catalytic activity of niobium oxide supported on zirconia

The development of the acidity and the relationship between acidity, catalytic activity, and the surface structure for niobium oxide supported on zirconia were investigated for a series of solids. The catalysts were active for 2-propanol dehydration only above a threshold in Nb loading. The acidity was studied by infrared spectroscopy of adsorbed 2,6-dimethylpyridine as a probe molecule, and the onset of activity was correlated with that of the formation of relatively strong Br?nsted acid sites. The variation in the abundance of these sites also correlated with the catalytic activity. Raman, IR, and UV spectroscopy results indicated that the active sites were related to polymeric Nb surface species. These results were compared to those previously reported for the WO(x)/ZrO(2) catalysts.     

A comparative study of the surface structure, acidity, and catalytic performance of tungstated zirconia prepared from crystalline zirconia or amorphous zirconium oxyhydroxide

Tungstated zirconias prepared from W deposition on zirconium oxyhydroxide are reportedly active for alkane isomerization, whereas solids synthesized by impregnation of zirconia are inactive. The origin of the differences between the two preparations is not fully understood. The present paper examines the influence of W surface density and the nature of the support on the surface structure, development of the acidity, and catalytic performance of WO(x)()/ ZrO(2) catalysts. Two series of catalysts containing W surface densities up to 5.2 at. W/nm(2) were prepared by pore volume impregnation of two different supports: zirconium oxyhydroxide and predominantly tetragonal zirconia (65% tetragonal, 35% monoclinic). The texture and structure of the catalysts were investigated by BET measurements, X-ray diffraction, Raman and infrared spectroscopy. The catalytic activity was tested for 2-propanol dehydration and n-hexane isomerization. For catalysts obtained by impregnation of Zr oxyhydroxide, Raman results showed that W was present as a surface phase. Infrared spectra indicated an increase in the degree of polymerization of W species with increasing W surface density. The development of the acidity was monitored by lutidine adsorption and desorption at 523 K, followed by infrared spectroscopy. The results indicated the presence of a threshold of W surface density at 1.3 at. W/ nm(2) for the detection of these acid sites, followed by a progressive increase in their abundance with increasing W surface density. The development of Br?nsted acidity correlated with the evolution of the infrared bands attributed to "extensively" polymerized W species. A direct relationship was observed between the abundance of Br?nsted acid sites and the catalytic activity for 2-propanol dehydration. For n-hexane isomerization, compared to 2-propanol dehydration, a higher threshold of W surface densities (3.4 at. W/ nm(2)) for the development of activity was observed. The difference was attributed to stronger Br?nsted acid sites required for n-hexane isomerization. The catalysts prepared by impregnation of zirconia exhibited comparable behavior. For a given W surface density, the crystalline composition of the support (tetragonal/monoclinic zirconia), the W surface structure, abundance of Br?nsted acid sites, and catalytic performance were similar. Thus, in an apparent variance with some of the results reported in the literature with respect to the influence of preparation methods, no significant effect of the initial form of the support (Zr oxyhydroxide versus predominantly tetragonal zirconia) was evidenced.     

Relations between structure, acidity, and activity of WOx/TiO2: influence of the initial state of the support, titanium oxyhydroxide, or titanium oxide

Two series of WO(x)/TiO(2) catalysts, containing W surface densities up to 4.4 W atoms/nm(2), were prepared by pore volume impregnation of two different supports, titanium oxyhydroxide (amorphous) or titanium oxide (crystallized, 100% anatase). The influence of W surface density and the nature of the support on the surface structure, development of the acidity, and catalytic performances were examined. The texture and structure of the catalysts were investigated by Brunauer-Emmett-Teller measurements, X-ray diffraction (XRD), and Raman and infrared spectroscopy. The catalytic activity was tested for 2-propanol dehydration and n-hexane isomerization. For catalysts obtained by impregnation of titanium oxide, XRD and Raman results showed that W was present as a surface phase. Infrared spectra indicated an increase in the degree of polymerization of W species with increasing W surface density. CO and lutidine adsorption, followed by infrared spectroscopy, showed an increase in the strength and abundance of Br?nsted acid sites (measured after lutidine desorption at 573 K) with the W surface density above a threshold of 1.3 W atoms/nm(2). The development of Br?nsted acidity correlated with the evolution of the infrared bands attributed to polymerized W species. A direct relationship was observed between the concentration of Br?nsted acid sites and the catalytic activity for 2-propanol dehydration. Catalytic activity, for n-hexane isomerization, appears to be associated with the presence of highly condensed W species. The catalysts synthesized by impregnation of titanium oxyhydroxide exhibited a comparable behavior. Hence, for a given W surface density, the W surface structure, concentration of Br?nsted acid sites, and catalytic performances were similar. Thus, no significant effect of the initial form of the support (titanium oxyhydroxide versus titanium oxide; 100% anatase) was evidenced.     

苯乙酮氢转移反应中ZrO2/MCM-41和ZrO2/AC的催化性能对比

采用浸渍法制备了分别以活性炭(AC)和全硅MCM-41介孔分子筛负载的ZrO2催化剂,并对其进行了XRD、氮气吸附-脱附、X射线光电子能谱、差热-热重分析和吡啶吸附原位红外光谱等表征,考察了其在以异丙醇为氢源还原苯乙酮为α-苯乙醇的Meerwein-Ponndorf-Verley(MPV)反应中的催化活性,并与水合ZrO2进行对比.研究了载体对催化剂活性的影响.结果表明,ZrO2经MCM-41负载后,与载体发生强相互作用,可能形成Si—O—Zr键,ZrO2在载体表面呈高分散的无定形态,Zr—OH数目显著增加,L酸性增强,并形成B酸中心,使催化剂活性显著高于水合ZrO2;ZrO2负载在AC上后,与载体未发生强相互作用,ZrO2在载体表面未呈高分散状态,增加的Zr—OH数目相对较少,L酸性较弱,未形成B酸中心,催化活性未明显增加,但在较高焙烧温度(400～600℃)下,其仍能保持稳定的催化活性,这可归因于ZrO2/AC中AC孔道疏通及AC石墨层对苯乙酮上苯环的吸附作用,使活性位附近的反应底物浓度显著增大.     

SO42-/ZrO2-Al2O3催化剂表面酸性质对正丁烷异构化反应性能的影响研究

采用“沉淀-浸渍”法制备一系列不同硫酸负载量的SO₄^2-/ZrO₂-Al₂O₃催化剂,利用N₂吸附-脱附、Py-FTIR、XRD等手段对催化剂进行表征。在常压、200 ℃、H₂：C₄=2：3和质量空速为3 h^-1的反应条件下,在固定床微型反应评价装置上考察了硫酸负载量对SO₄^2-/ZrO₂-Al₂O₃催化正丁烷异构化反应性能的影响。Py-FTIR结果表明,硫酸化处理为催化剂表面提供了丰富的Brønsted酸性位,其中,强Brønsted酸性位在正丁烷异构化反应中起重要作用,因此,硫酸化处理可显著提高正丁烷异构化活性,而Lewis酸性位与之没有直接关系。     

负载型ZrO2催化苯甲醛Meerwein-Ponndorf-Verley反应中的载体效应（英文）

采用浸渍法制备了Si-MCM-41和Al-MCM-41(Si/Al=50)介孔分子筛,SiO2,γ-Al2O3及MgO等负载的ZrO2催化剂,考察了其在以异丙醇为氢源苯甲醛Meerwein-Ponndorf-Verley(MPV)还原反应中的催化活性,并与纯ZrO2的催化活性进行对比.同时,采用X射线衍射、N2吸脱附法、X射线光电子能谱、紫外-可见漫反射光谱和吡啶原位吸附红外光谱等手段表征了催化剂.结果表明,ZrO2负载于Si-MCM-41,Al-MCM-41和SiO2后,催化活性明显提高,这归因于ZrO2与载体间存在强相互作用形成ZrOSi键,使催化剂表面ZrOH数量显著增多,Lewis酸中心强度增强,并出现Brnsted酸中心,三种催化剂的活性高低次序是5%ZrO2/Si-MCM-41>5%ZrO2/Al-MCM-41>5%ZrO2/SiO2.而5%ZrO2/Al2O3和5%ZrO2/MgO基本无催化活性,可归因为ZrO2与γ-Al2O3的弱相互作用使5%ZrO2/Al2O3的酸性与γ-Al2O3类似,ZrO2与MgO的强相互作用使5%ZrO2/MgO基本无酸性.     

氧化铝和氧化锆催化剂上2-取代苯并咪唑和1,5-二取代苯并二氮的合成(英文)

In this study, alumina, zirconia, manganese oxide/alumina, and manganese oxide/zirconia have been investigated for their catalytic activity in the condensation reaction between o-phenylenediamine and an aldehyde or a ketone to synthesise 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines respectively. Surface area, surface acidity, and morphology of the catalysts have been analysed and correlated with their catalytic activity. The isolated yields of 2-substituted benzimidazoles and 1,5-disubstituted benzodiazepines are in the range of 30% to 95%. A good correlation between the amount of surface acid sites as well as the surface morphology of the catalysts and the catalytic activity has been observed. This method has been found to be simple and economical. The solid supports could be regenerated and reused without much loss in their activity. Further, the solid supports have been also found to be effective as general catalysts in the condensation of o-phenylenediamine with other substituted aldehydes and ketones.     

BY分子筛的合成、表征及其裂化性能考察

采用水热晶化法合成了含杂原子硼的Y型分子筛，利用MAS NMR、XRD、IR等表征方法，证明了硼进入Y型分子筛的骨架中。利用吡啶吸附红外光谱、轻油微反装置分别测定了Y和BY分子筛的表面酸性及其裂化性能。结果表明，硼的引入增加了Y分子筛的B酸中心数目以及裂化和氢转移反应活性，导致裂化汽油中的烯烃明显降低，芳烃随之增加。     

锆助剂对低温液相合成甲醇用铜铬硅催化剂性能的影响

考察了含锆的铜铬硅催化剂低温液相合成甲醇性能，并进行了BET、TPR-H2、TPD-H2、TPD-CO、XRD和XPS表征。结果表明，锆作为结构助剂及电子助剂对催化剂在低温液相合成甲醇反应中具有显著的促进作用，反应活性可提高32.25 ％。锆助剂能有效提高催化剂的比表面积，促进催化剂中铜铬组分的分散及表面富集。ZrO2加入在催化剂表面产生的Cu+与催化活性的改善密切相关，Zr4+、Cr3+、Cu+可形成复合中心，为价态的稳定性提供微环境，在H2活化及C O键的断裂等反应步骤中起重要作用。     

Acid-base, electron donating and catalytic properties of sulfated zirconia

The electron donating properties of sulfated zirconia were studied from the adsorption of electron acceptors of various electron affinity. The surface acidity and basicity of the oxides have also been determined by titration method using a set of Hammett indicators. The data have been correlated with the catalytic activity of the oxide towards esterification of acetic acid usingn-butanol, reduction of cyclohexanol in 2-propanol and oxidation of cyclohexanol with benzophenone.     

Metal-reinforced sulfonic-acid-modified zirconia for the removal of trace olefins from aromatics

Metal-reinforced sulfonic-acid-modified zirconia catalysts were successfully prepared and used to remove trace olefins from aromatics in a fixed-bed reactor. Catalysts were characterized by ICP-OES, N₂ adsorption–desorption, X-ray diffraction, thermogravimetric analysis (TGA), and pyridine-FTIR spectroscopy. Different metals and calcination temperatures had great influence on the catalytic activity. Alumina-reinforced sulfated zirconia exhibited outstanding catalytic performance, stable regeneration activity, and giant surface area, and are promising in industrial catalysis. TGA showed that the decomposition of methyl could be attributed to Brønsted acid sites, and pyridine-FTIR spectroscopy proved the weak Brønsted sites on these synthesized metal-reinforced sulfated zirconia. Also, a relation between the reaction rate and weak Brønsted acid density is proposed.     

多钨酸盐修饰ZrO2气凝胶催化四氢呋喃开环聚合

采用过量浸渍结合溶剂蒸发将磷钨杂多酸(TPA)分散于ZrO₂气凝胶表面(TPA的质量分数为5%-45%), 再经750 °C空气气氛焙烧得到多钨酸盐修饰ZrO₂固体酸催化剂. 借助N₂吸附、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、氨程序升温脱附(NH₃-TPD)和吡啶吸附红外(Py-IR)光谱对催化剂的结构及酸性质进行表征, 针对四氢呋喃(THF)开环聚合反应考察其酸催化性能. 研究发现, TPA与ZrO₂之间较强的相互作用抑制了ZrO₂的晶化, 同时也在一定程度上稳定了TPA的Keggin(凯金)-阴离子结构. 高温焙烧的催化剂中, 活性组分以ZrO₂锚定的表面相(包括含有畸变或缺陷型Keggin单元的杂多酸盐及以Zr为杂原子的类杂多酸物种等)和TPA完全分解形成的氧化物体相存在, 各物种的相对量取决于TPA的负载量. 催化剂表面同时具有中等强度的布朗斯特德(Brönsted)酸与路易斯(Lewis)酸中心, 且初始TPA负载量为20%的催化剂实现了活性组分在载体表面的单层覆盖, 因而显示最大的总酸量, 对THF聚合反应也表现出最高的催化活性. 在反应温度为40 °C、时间为20 h条件下, 聚合物收率达30.9%±2%, 数均相对分子质量为2698±100; 在催化剂重复使用6次过程中, 活性未见明显降低.     

Influence of synthesis methods on tungsten dispersion, structural deformation, and surface acidity in binary WO3-ZrO2 system

WO3-ZrO2 catalysts were synthesized by precipitating the aqueous solutions of zirconium oxynitrate and ammonium metatungstate with ammonium hydroxide. The white slurry precipitate was treated under three different conditions. In the as-made materials, the amorphous phase was formed in the aged and refluxed samples, while well-crystallized tetragonal and monoclinic phases were obtained in the hydrothermally treated sample. The real amount of tungsten loaded in the samples was similar for the three samples, independently of the treatments; however, the tungsten surface atomic density in the annealed WO3-ZrO2 samples varied between 6 and 9 W atoms/nm2. Two different contrast types of aggregates were determined by scanning electron microscopy, the white particles which are rich in W, and the gray ones which are rich in zirconium; both of them were formed in the calcined solids prepared under aging or reflux condition. A very high dispersion of tungsten species on the zirconia surface was achieved in the hydrothermally treated sample. The degree of the interaction between WO(x) and ZrO2 surface strongly modified the Zr-O bond lengths and bond angles in the structure of tetragonal zirconia as proved by X-ray diffraction analysis and the Rietveld refinement. The catalyst obtained under hydrothermal condition exhibited the highest dispersion of tungsten species in the zirconia, which in turn causes strong structural deformation of the tetragonal ZrO2 phase responsible of the strongest surface acidity and, consequently, the optimum catalytic activity for n-hexane isomerization.     

载体表面性质对Cu/ZrO2催化剂CO加氢反应行为的影响

用XRD、LRS、NH₃-TPD、CO₂-TPD和CO-FTIR等表征手段考察了不同温度焙烧的氧化锆表面性质的差别,特别是表面酸碱性的差异对Cu/ZrO₂催化剂CO加氢反应行为的影响。结果表明,不同温度焙烧的氧化锆表面酸碱性具有较大的差异,其中以450℃焙烧的氧化锆具有较高的表面碱性和最低酸性。这些表面性质的差异对于Cu/ZrO₂催化剂的CO吸附行为产生较大的影响,进而影响CO的加氢反应活性。以450℃焙烧的氧化锆为载体时,Cu/ZrO₂催化剂具有较好的反应活性。     

表面酸性对Ni/SiO_2-Al_2O_3催化剂催化1,4-丁炔二醇高压加氢性能的影响

通过浸渍法分别在Al(OH)_3和Al_2O_3中引入SiO_2,经焙烧后制备具有不同表面酸性质的SiO_2-Al_2O_3载体,以上述SiO_2-Al_2O_3及Al_2O_3为载体,采用等体积浸渍法制备Ni负载量为15%的Ni/SiO_2-Al_2O_3催化剂(分别为Ni/SA-1和Ni/SA-2)与Ni/Al_2O_3.采用N2物理吸附、Py-FTIR、NH3-TPD、XRD、H2-TPR和H2-TPD手段对催化剂进行表征,考察了表面酸性质对催化剂催化1,4-丁炔二醇高压加氢性能的影响.结果表明,SiO_2引入方式会影响Ni/Al_2O_3催化剂表面酸性质及活性组分Ni在载体表面的分散行为.在Al(OH)3中引入SiO_2时,Ni/SA-1催化剂不仅活性组分具有高分散度,而且表面具有丰富的L酸位点,L酸位点与Ni活性中心协同作用有效提高了催化剂的高压加氢性能.而在Al_2O_3中直接引入SiO_2时,SiO_2覆盖了Al_2O_3表面的L酸位点,催化剂活性组分分散度较低,表现出低的加氢活性.     

稀土改性对SO42-/ZrO2固体酸催化剂结构与催化性能的影响

采用共沉淀法和浸渍法在不同条件下制备了稀土-SO₄^2-/ZrO₂系列固体酸催化剂。使用废油脂与甲醇的酯交换反应评价了催化剂活性,并通过X射线衍射、红外光谱、比表面积测定表征方法考察了催化剂结构和性能的关系。结果表明,La摩尔掺杂量4%、焙烧温度600℃时制得的SO₄^2-/ZrO₂-La₂O₃催化剂活性最高,此时脂肪酸甲酯的产率为64.68%,且具有较好的重复使用性。稀土的引入使活性四方相ZrO₂更加稳定,600℃焙烧使催化剂既具有较多活性四方相ZrO₂,又具有较大比表面积,从而提高了催化剂活性。催化剂中形成了固体超强酸结构,且改性后酸强度增大,催化剂活性中心数目增加。     

Catalytic Combustion of Methane over High Copper-Loading ZSM-5 Catalysts

Two series of Cu/ZSM-5 catalysts,loading from 5 to 20 wt% CuO,were prepared by the deposition-precipitation and impregnation methods,respectively.The catalysts prepared by the impreg- nation method showed better catalytic performances than those prepared by the deposition-precipitation method and the increase of copper loading favored methane conversion.20Cu(I)/ZSM-5 had the highest activity with T_(90%)of 746 K,and for 20Cu(D)/ZSM-5,T_(90%)was as high as 804 K.The characteriza- tion of X-ray diffraction(XRD),temperature-programmed reduction(TPR),temperature-programmed desorption(TPD),and X-ray photoelectron spectroscopy(XPS)revealed that the dispersion of cop- per species could be improved by using the deposition-precipitation method instead of the impregnation method,but the fraction of surface CuO,corresponding to active sites for methane oxidation,was larger on 20Cu(I)/ZSM-5 than 20Cu(D)/ZSM-5.The results of Pyridine-Fourier transform infrared spectrum (Py-FT-IR)showed that a majority of Lewis acidity and a minority of Brφnsted acidity were present on Cu/ZSM-5 catalysts.20Cu(I)/ZSM-5 presented more Lewis acid sites.The number of Lewis acid sites changed significantly with preadsorption of oxygen.Adsorption of methane and oxygen on acid sites was observed.The properties of Cu/ZSM-5 catalysts were correlated with the activity for methane oxidation.     

载体对Pt/WO_3-ZrO_2催化临氢异构反应性能的影响

以平衡吸附过氧钨酸的水合氧化锆为前驱体,经焙烧得到WO_3-ZrO_2固体酸,并采用XRD、UV-vis、NH_3-TPD等手段考察了过氧钨酸吸附液浓度及焙烧温度对WO_3-ZrO_2固体酸组成、结构及酸性的影响。通过BET、H_2-TPR、H_2-TPD等表征手段和正戊烷临氢异构反应,考察了负载铂后相应催化剂的结构、还原与氢吸附性质及其催化正戊烷临氢异构反应的性能。结果表明,焙烧温度为700℃时,随着吸附液浓度的增加,所得载体酸度及相应催化剂比表面积均先增加后减小,且在吸附液浓度为82 mmol W/L时达到最大值。吸附液浓度为59 mmol W/L时,随着焙烧温度的升高,所得载体四方相氧化锆含量、酸度及相应催化剂比表面积均降低。吸附液浓度为82 mmol W/L、焙烧温度为700℃所得载体负载0.5%(质量分数)铂后催化活性最高。该催化剂在250℃常压临氢操作、n(H_2)/n(n-C_5H_(12))为3、WHSV为1.0 h~(-1)的条件下,催化正戊烷异构反应中异戊烷收率可达57.7%。     

ZrO_2晶相对MoO_x/ZrO_2催化剂结构及其甲醇选择氧化性能的影响

以纯的单斜氧化锆(m-ZrO2)和四方氧化锆(t-ZrO2)为载体,采用浸渍法分别合成了具有不同MoOx表面密度的MoOx/m-ZrO2和MoOx/t-ZrO2催化剂,并结合粉末X射线衍射,Raman光谱和H2程序升温还原等技术表征了不同ZrO2晶相对MoOx分散状态、结构以及甲醇氧化反应性能的影响.在低于锆表面MoOx的单层分散阈值(～5nm-2)时,m-ZrO2比t-ZrO2能够更有效地分散MoOx,形成高分散的孤立或二维结构的MoOx物种,避免了晶相MoO3的出现.当Mo表面密度超过单层分散阈值后,经过600℃焙烧,MoOx与ZrO2载体发生固相反应生成晶相ZrMo2O8,m-ZrO2比t-ZrO2更有利于ZrMo2O8的生成.提高Mo表面密度,催化剂表面的酸性随之增强,说明晶相ZrMo2O8比分散的MoOx物种具有更强的酸性.t-ZrO2与MoOx作用形成的强酸中心更有利于催化甲醇脱水生成二甲醚,但m-ZrO2使得MoOx具有更高的氧化还原能力和催化甲醇选择氧化反应的活性.ZrO2晶相对MoOx/ZrO2催化剂影响的研究结果将有助于研究VOx等其它金属氧化物催化剂以及发展酸性和氧化还原性双功能催化剂体系.     

氧化钛负载脱硝催化剂的碱中毒过程：氧化钒的保留和氧化钨的牺牲

V2O5-WO3/TiO2催化剂目前已广泛用于电厂和工业锅炉燃烧废气脱硝,但燃烧原料煤及石油中含有的杂质元素碱金属与碱土金属元素可吸附在催化剂上,不仅会减少催化剂酸性位的数量,还会与催化活性元素结合生成惰性物种,导致催化剂失活。因此,已有许多有关钒钨钛催化剂碱中毒的研究,从催化剂的氧化还原能力、酸性位损失及表面孔结构等方面进行了讨论。但这些研究大多集中在碱中毒对活性组分V2O5的影响及中毒催化剂的活性变化,很少涉及催化剂中WO3的作用,也缺乏有关不同活性元素与钾盐反应的实验证据。本文采用过量浸渍法制备了不同钒和钨含量的钒钨钛催化剂,研究了氯化钾对其氨法选择性催化还原(NH3-SCR)活性的失活效应。利用感应耦合等离子体、N2吸附、拉曼光谱、H2程序升温还原、NH3吸附红外光谱和NH3氧化活性等手段对新鲜和中毒催化剂的性质进行了表征,特别探讨了V2O5和WO3对催化剂抗碱中毒能力的贡献。
　　催化剂活性测试结果表明, V2O5含量越高,活性温度窗口越宽,而且含有WO3的三元催化剂活性高于V2O5/TiO2二元催化剂。催化剂的BET比表面积和孔结构取决于TiO2载体,随活性组分配比变化不大,说明催化剂物理结构性质并非影响活性的主要因素。原位红外光谱及H2程序升温还原测试结果表明,随V2O5含量提高,催化剂表面Br?nsted酸性位数量及氧化还原能力提高。作为反应的主要活性物种, V2O5在碱中毒处理后变成惰性的偏钒酸钾KVO3,使催化剂中Br?nsted酸性位减少,热稳定性下降,并削弱了催化剂的氧化还原能力,因此低钒含量的催化剂容易严重中毒失活。在高钒负载量(3%)时,部分V2O5在碱中毒后得以保留,从而使催化剂保持了一定的脱硝催化活性。
　　另外, WO3能给催化剂表面提供热稳定的酸性位,虽然WO3自身的氧化还原能力差,但其能改善V2O5的分散性,从而提高V2O5-WO3/TiO2催化剂的活性。除此之外, WO3在催化剂碱中毒过程中还能扮演牺牲剂,与钾反应生成钨酸钾(K2WO4),即在V2O5与钾离子结合形成KVO3的同时,部分WO3也会与钾反应形成K2WO4,可以使三元催化剂保留更多的活性V物种。因此,在所研究的催化剂中,高钒负载量的V2O5-WO3/TiO2催化剂表现出最好的抗碱中毒能力。
　　活性影响因素分析表明,对于新鲜催化剂,其表面吸附的NH3量足够多,催化剂活性与表面酸性相关度不大,脱硝效率主要取决于催化剂的氧化还原能力。但是,对于碱中毒处理后的催化剂,其表面吸附NH3的能力大大削弱,这时脱硝效率除了受催化剂氧化还原能力影响,在很大程度上也依赖于催化剂的表面酸性。