废弃脱硝催化剂选择性提取钒和钨

废弃脱硝催化剂富含钛、钨等有价金属,但同时也含有毒性较大的砷、汞、铅等有害物质,目前未得到工业应用,不仅浪费资源,还对环境造成巨大压力。针对失效脱硝催化剂,开展了综合回收研究,提出了“低温活化—选择性浸出—树脂交换”工艺技术路线。通过试验研究,钒、钨的浸出率分别可达96.29%和88.10%,钛基本被抑制在渣中,实现了钒、钨的选择性浸出;浸出渣可直接作为催化剂基体原料或采用硫酸法（或氯化法）制备高品质钛白,通过酸解—水浸—水解后可获得TiO2含量为99%的二氧化钛。     

废弃SCR脱硝催化剂资源化利用研究进展

废弃SCR脱硝催化剂是一种危险废物,同时又含有多种有价成分。通过分析国内外废弃催化剂资源化利用的主要方法、原理、途径及优缺点,得到能够充分回收钒钨钛资源的有效方法主要为废弃SCR脱硝催化剂浸出-浸出液净化分离回收钒钨-浸出渣酸洗焙烧回收钛,其中浸出过程比较适合采用碱式焙烧-水浸法;浸出液净化分离过程比较适合采用化学沉淀法或溶剂萃取结合化学沉淀法。此外,展望了废弃SCR脱硝催化剂资源化利用的研究方向。     

废SCR脱硝催化剂钒钨提取研究进展

含有钒、钨和钛的选择性催化还原催化剂在许多工业应用中被广泛还原氮氧化物。各行业脱硝催化剂正在进入报废更换高峰期,处理废催化剂回收有价金属迫在眉睫。将回收的钒、钨、钛用于生产新型催化剂或其他产品,可形成循环经济。对废脱硝催化剂钒钨提取工艺进行详细综述,重点介绍钒钨浸出和钒钨分离方法。     

燃煤电厂废弃催化剂回收钒的研究

废弃SCR催化剂中含有V、W和Ti等多种有价金属,直接弃置不仅会造成环境污染,还会造成资源的浪费,因此回收其中的有价金属具有重大意义。提出采用湿法冶金的方法,通过Na OH碱性浸出法一次性浸出废弃催化剂中的V和W,然后对浸出液进行钙化沉淀,通过甲酸选择性浸出钙混合沉淀物中的钒,经过除杂,加入氨水,钒将以偏钒酸铵的形式沉淀出来;甲酸浸出后沉淀物中的钨,加入盐酸转化为钨酸,经过灼烧,最终生成三氧化钨。通过试验确定了Na OH碱性浸出法最佳工艺条件和甲酸选择性浸出最佳反应条件。     

烧结烟气中含钾化合物对钒钨钛催化剂脱硝/二噁英性能的影响

采用钒钨钛催化剂可有效减排烧结烟气中NO和二噁英,而烟气中含有的钾盐会造成催化剂活性降低。在实验室采用湿式浸渍法对新鲜钒钨钛催化剂进行强制失活,研究了三种钾盐（K₂SO₄、K₂O和KCl）负载于催化剂表面对其脱硝和脱二噁英活性的影响,并采用水洗和酸洗手段考察了失活催化剂的再生性能。结果表明,不同形态钾盐会造成催化剂的脱硝和脱二噁英活性降低,催化剂对两种污染物的活性降低顺序遵循相同的规律,即KCl> K₂O> K₂SO₄。催化剂的失活机理主要包括物理失活和化学失活。物理失活主要是指钾盐在催化剂表面沉积并堵塞其孔道;化学失活主要是指钾盐与催化剂表面的活性组分产生相互作用,钝化表面活性位点,降低表面酸性,减弱氧化和还原性能,进而降低催化剂的脱硝和脱二噁英活性。再生实验结果表明,水洗可以一定程度上恢复催化剂的脱硝活性,酸洗会导致催化剂表面活性物质流失,但水洗和酸洗均无法有效恢复催化剂的脱二噁英活性。最后,提出了不同形态钾盐对钒钨钛催化剂的中毒机理。      

高炉处理烧结烟气脱硫脱硝理论分析

对利用高炉处理烧结烟气同时脱硫脱硝脱二噁英技术的可行性进行了理论探讨,分析高炉内部还原二氧化硫和氮氧化物,以及分解二噁英的热力学条件,探讨烧结烟气代替空气鼓风对理论燃烧温度、风量、炉缸煤气、炉顶煤气和铁水硫含量的影响.结果表明:二氧化硫、一氧化氮和二氧化氮的最低平衡体积分数分别为1.84×10^-13%、3.08×10^-11%和3.72×10^-21%,高炉内部还原二氧化硫和氮氧化物是可行的;高炉具有分解二噁英的有利热力学条件;烟气中二氧化硫和一氧化碳对理论燃烧温度的影响可忽略,氮氧化物能略微提高理论燃烧温度,二氧化碳体积分数增加1%,理论燃烧温度降低大约40.5℃,但通过降低鼓风湿度和提高富氧率等措施,能达到高炉正常生产时的炉缸热状态水平;随着烟气中二氧化碳含量的增加,风量、炉缸和炉顶煤气量都逐渐降低,炉缸煤气一氧化碳和氢气含量增加,炉顶煤气中一氧化碳、氢气、二氧化碳和水含量都增加,氮气含量显著降低;铁水硫含量与烟气二氧化硫含量成正比,但当二氧化硫质量浓度达到2000 mg·m^-3,铁水中硫质量分数仅为0.025%,铁水质量仍合格.通过综合调节高炉操作参数,也可以实现烧结烟气代替空气鼓风进行高炉炼铁生产,达到脱硫脱硝脱二恶英的目的.     

烧结烟气低温SCR脱硝催化剂半工业化试验

低温SCR是烧结烟气脱硝技术发展的主要方向,而催化剂是其中的关键因素.针对烧结烟气的特点,研发出低温平板式抗碱脱硝催化剂.为了明确该催化剂的低温脱硝活性、运行稳定性、积灰特性和抗碱金属中毒能力,在太钢450 m2烧结机活性炭脱硫脱硝装置后进行了低温SCR脱硝催化剂半工业化试验.结果表明,在150℃的烟气温度下,催化剂脱...     

微波消解-电感耦合等离子体原子发射光谱法测定废脱硝催化剂中钨和钛

选择酒石酸-氢氟酸-硝酸体系并利用微波消解处理样品,使用电感耦合等离子体原子发射光谱法(ICP-AES)测定钨和钛,建立了微波消解-电感耦合等离子体原子发射光谱法测定废脱硝催化剂中钨和钛的方法。试验考察了消解体系及用量,优化了微波消解程序。结果表明,钨和钛的质量浓度分别为0.05~5mg/L和0.01~10mg/L与其相应的发射强度呈线性关系,相关系数分别为0.9995、0.9998,检出限分别为0.002%、0.0002%。废脱硝催化剂中铁、铝、钙、镁、钒和钼等元素对钨和钛的测定无影响。方法用于废脱硝催化剂样品中钨和钛的测定,结果的相对标准偏差(RSD,n=6)均小于3%,并与原子吸收光谱法(AAS)测定值一致。     

碱熔-电感耦合等离子体原子发射光谱法测定废弃SCR脱硝催化剂中钨

SCR废催化剂中钨的测定一般采用碱溶-硫氰酸盐分光光度法,但由于此类催化剂中含有钒,而钒(Ⅲ)能与SCN-形成绿色络合物,从而导致测定受到干扰.实验采用过氧化钠熔解试样,直接用水浸取后定容,稀释试液后加入1 g/L酒石酸溶液并控制盐酸酸度为5％,选择W 207.912 nm为分析谱线,采用电感耦合等离子体原子发射光谱法...     

太钢烧结烟气脱硫脱硝用热气再生系统实践

简单介绍了活性炭脱硫脱硝技术在太钢烧结厂烟气脱硫中的应用,重点介绍热气再生系统的工作参数、工艺流程、主要设备和技术特点,利用热气再生系统使活性炭循环使用,再生效果好,运行后环保效果非常明显,经济效益好。最大限度的降低了能耗、实现综合再利用,大大降低了活性炭脱硫的运行成本,有较大的推广价值。     

TiSiW12O40/TiO2催化合成丙酸系列酯

以固载杂多酸盐TiSiW₁₂O₄₀/TiO₂为多相催化剂,对以乙醇、正丙醇、正丁醇、正戊醇、异戊醇和丙酸为原料合成丙酸系列酯的反应条件进行了研究.实验表明TiSiW₁₂O₄₀/TiO₂是合成丙酸系列酯的良好催化剂.通过较系统地研究醇酸的物质的量的比、催化剂用量、反应时间诸因素对酯收率的影响,得到合成丙酸系列酯的最佳反应条件.     

Effects of La2O3/Li2O/TiO2- Coating on Electrochemical Performance of LiCoO2 Cathode

Conventional cathode material （LiCoO2） was modified by coating with a thin layer of La2O3/Li2O/TiO2 for improving its performance for lithium ion battery. The morphology and structure of the modified cathode material was characterized by SEM, XRD, and Auger electron spectroscopy. The performance of the cells with the modified cathode material was examined, including the cycling stability, the diffusion coefficient under different voltages, and the C-rate discharge. The results showed that the cell composed of the coated cathode material discharged at a large current density, and possesses a stable cycle performance in the range from 3.0 to 4.4 V. It was explained that the rate of Li ion diffusion increased in the cell while using La2O3/Li2O/TiO2-coated LiCoO2 as the cathode and the coating layer may act as a faster ion conductor （La2O3/Li2O/TiO2）.     

La_2O_3掺杂对V_2O_5-WO_3/TiO_2催化剂SCR性能的影响

通过共沉淀法将La组分掺入到TiO_2载体中,采用浸渍法将V和W组分负载到La_2O_3-TiO_2复合氧化物上,制备出V2O5-WO3/La_2O_3-TiO_2催化剂。考察不同La_2O_3掺杂量对其NH3催化还原NO性能的影响,同时通过多种物理化学手段进行表征分析。XRD,NH_3-in situ DRIFTS,H_2-TPR,XPS和UV-vis DRS测试结果表明,元素La与Ti以La-O-Ti键相互作用,生成高度分散的镧物种,也使得TiO_2具有更好的热稳定性,但由于LaO_x物种与VO_x物种和WO_x物种之间的相互作用,降低了催化剂的氧化还原性和表面Brnsted酸数量,从而降低了其催化活性。     

TiO2对合成渣中Fe2O3还原发泡过程的影响

研究了不同条件下TiO₂和Fe₂O₃在合成渣中被碳还原时的发泡过程.计算了该发泡过程的发泡系数、消泡系数、平均发泡寿命、发泡强度和消泡过程开始的时间.用熔渣发泡参数定量地讨论了温度、TiO₂加入量和初渣中TiC的含量对熔渣发泡过程的影响,发现当初渣中TiC的含量和TiO₂加入量较多时,在发泡时会产生二次发泡现象.     

Effect of Fe2O3 Loading Amount on Catalytic Properties of Monolithic Fe2O3/Ce0.67Zr0.33O2 -Al2O3 Catalyst for Methane Combustion

Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33 O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8% （ mass fraction）. The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe203 was 8% （ mass fraction）, the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results.     

Regeneration of the deactivated TiO2-ZrO2-CeO2 /ATS catalyst for NH3-SCR of NOx in glass furnace

Larger amounts of alkalis, alkali earth metals and sulfides in flue gas from glass furnace were easier to deactivate selective catalytic reduction (SCR) catalyst compared to the flue gases from other stationary sources. Catalyst regeneration has been an emerging research topic for flue gas denitrification in glass furnace. Regeneration of the deactivated TiO2-ZrO2-CeO2 /Al2TiO 5 -TiO2-SiO2 (ATS) complex phase ceramics catalysts used for NH3 -SCR of NO x in glass furnace was studied in this work. Effects of regeneration methods, including washing with different aqueous solutions and sulfuric acid, thermal regeneration, thermal reduction regeneration, and thermal regeneration with SO2 , on catalytic performance were comparatively investigated. In comparison of catalytic activities between the catalysts before and after regeneration, results showed that washing was the most effective regeneration method, and the sulfuric acid concentration of the washing solution was an important factor. Washing time directly affected catalyst regeneration efficiency and catalyst life. The regenerated TiO2-ZrO2 -CeO2 /ATS catalyst regained more than 90% NO conversion after being washed with 10 wt.% H2SO4 for 30 min.     

Influence of B2O3 on Spectroscopic Properties of Er^3＋/Yb^3＋ Co-Doped Tungsten-Tellurite Glasses

A series of novel Er^3＋/Yb^3＋ co-doped （85- x ） TeO2-15WO3-xB2O3 （TWB;x=2%,5%,8%（mole fraction） ） glasses were prepared. Influence of B203 on the spectroscopic properties of Er^3＋/Yb^3＋ co-doped tungsten-tellurite glasses were investigated. It is found that the intensity of 1.5μm fluorescence, lifetime of the ^4I13/2 level and upconversion fluorescence all decrease with the increase of B2O3 content. The product of full width at half maximum （FWHM） and stimulated emission cross-section （σe^peak） of Er^3＋ ：^4I13/2→^4I15/2 transition has an optimum when B203 is 5% （mole fraction）. The emission spectra of Er^3＋ ： ^4I13/2→^4I15/2 transition was analyzed using peak-fit routine, and an equivalent four-level system was proposed to estimate the stark splitting for the 411512 and ^4I13/2 levels of Er^3＋ ions in TWB glasses at room temperature.     

Synthesis of Al2O3/TiCN-0.2%Y2O3 Composite by Hot Pressing

Al2O3/TiCN composites were synthesized by hot pressing.The influences of components and HP temperature on mechanical properties,such as bending strength,breaking tenacity and Vickers hardness were investigated.The results showed that the mechanical properties of Al2O3/TiCN composite increased with temperature when hot pressing temperature is below 1650 ℃.The mechanical properties reached their maximums when the composites were sintered at 1650 ℃ for 30 min under hot pressing pressure of 35 MPa,the value of bending strength,breaking tenacity and Vickers hardness was 1015 MPa,6.89 MPa·m1/2,and 20.82 MPa,respectively.When hot pressing temperature was above 1650 ℃,density decreased because of decomposition with increased temperature,and mechanical properties dropped because of rapid growth of grains in size at high temperature.Microstructure analysis showed that the addition of Y2O3 led to the formation of YAG phase so as to inhibit the growth of crystals.This helped to improve breaking tenacity of the composites.TiCN particles with diameters of 1 μm dispersed at Al2O3 grain boundaries,inhibited grain growth and enhanced mechanical properties of the composites.SEM study of the propagation of indentation cracks showed that the bridge linking behavior between matrix and strengthening phase might lead to the formation of the coexisted field of crack deflection,branching and bridge linking.The mechanism of this phenomenon was that the addition of Y2O3 improved the dispersion of TiCN particles so as to enhance the tenacity of the composites.The breaking tenacity was changed from 5.94 to 6.89 MPa·m1/2.     

Catalytic Partial Oxidation of Methane over Ni/CeO2-ZrO2-Al2O3

Nickel catalysts supported on CeO2-ZrO2-CeO2,ZrO2-Al2O3 and Al2O3 were prepared and characterized by means of X-ray diffraction（XRD）,BET areas,H2 temperature-programmed reduction（H2-TPR）,and X-ray photoelectron spectroscopy（XPS）.Through the test of catalytic partial oxidation of methane（CPOM）,Ni/CeO2-ZrO2-Al2O3 displayed the highest activity,which resulted from its largest BET area and best NiO dispersion.Furthermore,Ni/CeO2-ZrO2-Al2O3 maintained a long-time stability in CPOM,which was attributed to its best coking resistance among all the prepared catalysts.     

不烧Al2O3-C质耐火材料在水蒸气中的抗氧化性能

对高炉炉身下部用不烧Al₂O₃-C质耐火材料在水蒸气环境下的抗氧化性能进行了详细的热力学分析和全面的氧化性能实验.根据实验结果,总结出其氧化规律,建立了不烧Al₂O₃-C质耐火材料的氧化动力学模型.此外,还对氧化前后试样的抗折强度进行了测定和比较.