MgO改性MoO_(3)-V_(2)O_(5)-TiO_(2) SCR催化剂的低温脱硝研究

采用浸渍法制备了低温脱氮的Mg-Mo-V-Ti催化剂。为了研究催化剂的活性,将其置于固定床反应器中,用钢瓶气体模拟工业烟气的组分及浓度。结果表明,0.1%的氧化镁催化剂具有良好的脱硝活性和抗硫性能。研究了0.1MgO-6MoO_(3)-3V_(2)O_(5)-TiO_(2) wt%催化剂活性的工艺条件:(1)当氧质量分数小于8.0%时,随着氧质量分数增加,脱硝效率提高,当氧质量分数大于8.0%时,脱硝效率几乎相同;(2)脱硝效率随着空速的增大而降低;(3)随着温度的升高,催化剂的脱硝效率先升高后趋于稳定,当反应温度高于180℃时,脱硝性能可达94.3%,在120~240℃,SO_(2)的转化率小于0.3%。

帕金森病患者外周血清可溶性补体受体2的变化及意义

目的 通过检测帕金森病 (Parkingsondisease,PD)患者外周血清可溶性补体受体 2 (solublecomplementreceptor 2 ,sCR2 )的浓度 ,探讨炎症反应在PD发病机制中的作用。方法 以 8例脑梗死 (cerebralinfarction ,CI)患者和 8例健康查体者为对照 ,采用双抗体夹心酶联免疫吸附实验法检测了 2 4例PD患者外周血清sCR2的浓度。结果 PD患者按照Webster量表评分和病程分组后与CI患者和健康查体者进行比较 ,发现PD轻度组 (99.7± 18.3)U/L与CI组 (92 .5± 13.7)U/L及正常对照组 (95 .8± 15 .9)U/L相比 ,sCR2浓度差别无统计学意义 (P分别 >0 .0 5 ) ;而PD中度组 (70 .2± 12 .4 )U/L与各组相比差别均有统计学意义 (P 分别 <0 .0 1) ;CI组与正常对照组相比较差别无统计学意义 (P >0 .0 5 ) ;PD(<3年组 ) (10 1.5± 16 .8)U/L与CI组和正常对照组相比 ,sCR2浓度差别无统计学意义(P分别 >0 .0 5 ) ;PD(3～ 6年组 ) (6 4 .4± 13.1)U/L与各组相比差别均有统计学意义 (P分别 <0 .0 1)。结论 PD患者外周血清sCR2的减少提示患者体内炎症反应过度 ,可能是PD病情加重的原因之一 ,抗炎治疗可能会延缓PD患者病情的发展。

舒血宁注射液联合依帕司他对糖尿病肾病患者血清Scr、β2-MG水平的影响

目的:研究舒血宁注射液联合依帕司他对糖尿病肾病患者血清肌酐(Scr)、尿β2微球蛋白(β2-MG)水平变化及生活质量的影响。方法:选取我院2016-02~2017-07糖尿病肾病患者84例作为研究对象,按治疗方案不同分组,各42例。对照组采用依帕司他治疗,对照组采用依帕司他+舒血宁注射液治疗。治疗1个月后,比较两组治疗效果、治疗前后血清Scr、β2-MG水平及生活质量(SF-36)评分。结果:两组总有效率比较,观察组95.24%高于对照组76.19%,差异有统计学意义(P<0.05);治疗前,两组血清Scr、β2-MG水平、SF-36评分比较,差异无统计学意义(P>0.05);治疗1个月后,观察组SF-36评分高于对照组,血清Scr、β2-MG水平低于对照组,差异有统计学意义(P<0.05)。结论:舒血宁注射液联合依帕司他治疗糖尿病肾病患者,疗效显著,可降低血清Scr、β2-MG水平,提高生活质量。

GE R-500 X线拍片机的故障分析与检修

本文通过实例介绍GE公司R-500 X线拍片机在使用过程中出现的几种故障及其检修方法。

血清胱抑素C检测在慢性肾病早期临床应用评价

目的了解血清胱抑素C的检测在慢性肾病患者中的临床意义.方法：对63例糖尿病肾病,35肾病综合症42例高血压慢性肾病患者与68名正常人群,按GFR 分为A,B,C三组分别测各组血清CysC,GFR,Scr,尿mAlb 和尿β2-MG.结果：CysC 作为评价肾功能的重要内源性指标,在慢性肾病早期临床应用中越来越受到重视,本研究表明慢性肾病血清CysC随病情进展敏感性,特异性和准确性明显高于Scr,尿mAlb 和尿β2-MG 结论：CysCGFR 尿mAlb 和尿β2-MG 作为慢性肾病早期诊断的指标CysC更能准确的反应慢性肾病病人的GFR,对于监测慢性肾病早期更具有临床应用价值.

芹菜素上调SHP-1蛋白表达抑制肝癌MHCC97H细胞STAT3磷酸化及球形成

目的 :研究芹菜素抑制肝癌MHCC97H细胞球形成是否涉及上调Scr同源结构域2磷酸酶-1(SHP-1)蛋白表达和抑制信号转导子和转录激活因子-3(STAT3)磷酸化。方法 :芹菜素(10、20和40μM)处理MHCC97H细胞或SHP-1 siRNA转染细胞;球形成法测定肿瘤球形成率;蛋白质印迹分析细胞SHP-1和p-STAT3蛋白表达。结果 :芹菜素以浓度依赖方式降低MHCC97细胞球形成率,同时上调SHP-1蛋白表达以及抑制STAT3蛋白磷酸化。SHP-1 siRNA转染减弱芹菜素抑制MHCC97细胞STAT3蛋白磷酸化和球形成的作用。结论 :芹菜素上调SHP-1蛋白表达,进而降低STAT3蛋白磷酸化水平参与抑制MHCC97肝癌细胞球形成作用。

NH_3-SCR denitration catalyst performance over vanadium–titanium with the addition of Ce and Sb

Selective catalytic reduction technology using NH3 as a reducing agent（NH3-SCR） is an effective control method to remove nitrogen oxides. TiO2-supported vanadium oxide catalysts with different levels of Ce and Sb modification were prepared by an impregnation method and were characterized by X-ray diffractometer（XRD）, Brunauer-Emmett-Teller（BET）, Transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FT-IR）, UV-Vis diffuse reflectance spectroscopy（UV-Vis DRS）, Raman and Hydrogen temperature-programmed reduction（H2-TPR）. The catalytic activities of V5 CexS by/TiO2 catalysts for denitration were investigated in a fixed bed flow microreactor. The results showed that cerium, vanadium and antimony oxide as the active components were well dispersed on TiO2, and the catalysts exhibited a large number of d-d electronic transitions, which were helpful to strengthen SCR reactivity. The V5 CexS by/TiO2 catalysts exhibited a good low temperature NH3-SCR catalytic activity. In the temperature range of 210 to 400℃, the V5 CexS by/TiO2 catalysts gave NO conversion rates above 90%. For the best V5Ce35Sb2/TiO2 catalyst, at a reaction temperature of 210℃, the NO conversion rate had already reached 90%. The catalysts had different catalytic activity with different Ce loadings. With the increase of Ce loading, the NO conversion rate also increased.

Effect of Ce doping of TiO_2 support on NH_3-SCR activity over V_2O_5–WO_3/CeO_2–TiO_2 catalyst

CeO2–TiO2composite supports with different Ce/Ti molar ratios were prepared by a homogeneous precipitation method, and V2O5–WO3/CeO2–TiO2catalysts for the selective catalytic reduction（SCR） of NOx with NH3 were prepared by an incipient-wetness impregnation method. These catalysts were characterized by means of BET, XRD, UV–Vis,Raman and XPS techniques. The results showed that the catalytic activity of V2O5–WO3/TiO2 was greatly enhanced by Ce doping（molar ratio of Ce/Ti = 1/10） in the TiO2 support.The catalysts that were predominantly anatase TiO2 showed better catalytic performance than the catalysts that were predominantly fluorite CeO2. The Ce additive could enhance the surface adsorbed oxygen and accelerate the SCR reaction. The effects of O2 concentration, ratio of NH3/NO, space velocity and SO2 on the catalytic activity were also investigated. The presence of oxygen played an important role in NO reduction. The optimal ratio of NH3/NO was 1/1 and the catalyst had good resistance to SO2 poisoning.

Novel CeO_2@TiO_2 core–shell nanostructure catalyst for selective catalytic reduction of NOx with NH_3

The CeO2@TiO2 core-shell nanostructure catalyst prepared by a two-step hydrothermal method was used for selective catalytic reduction （SCR） of NOx with NH3 in this study. The catalyst presented the obvious core-shell structure, and the shell was amorphous TiO2 which could protect the active center from the SO2 erosion. The catalyst showed high activity and stability, excellent N2 selectivity and superior SO2 resistance and H2O tolerance. Characterizations such as TEM, HR-TEM, XRD, BET, XPS, NH3-TPD, and H2-TPR were carried out. The results indicated that the catalyst had large surface area and the active sites were well dispersed on the surface. The NH3-TPD, H2-TPR and XPS results implied that its increased SCR activity might be due to the enhancement of NH3 chemisorption and the increase of active oxygen species, both of which were conductive to NH3 activation. The excellent catalytic performance suggests that it is a promising candidate for SCR catalyst.

Effect of SiO2 addition on NH4HSO4 decomposition and SO2 poisoning over V2O5-MoO3/TiO2-CeO2 catalyst

The deposition of NH4 HSO4 and the poisoning effect of SO2 on SCR catalyst are the main obstacles that restrict the industrial application of CeO2-doped SCR catalysts.In this work,deposited NH4 HSO4 decomposition behavior and SO2 poisoning over V2 O5-MoO3/TiO2 catalysts modified with CeO2 and SiO2 were investigated.By the means of characterization analysis,it was found that the addition of SiO2 into VMo/Ti-Ce had an impact on the interaction existed between catalyst surface atoms and NH4 HSO4.Temperatureprogrammed methods and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS)experiments indicated that the doping of SiO2 promoted the decomposition of deposited NH4 HSO4 on VMo/Ti-Ce catalyst surface by reducing the thermal stability of NH4 HSO4 and enhancing the NH4 HSO4 reactivity with NO in low temperature.And this improvement may be the reason for the better catalytic activity than VMo/Ti-Ce in the case of NH4 HSO4 deposition.Accompanied with cerium sulfate species generated over catalyst surface,the conversion of SO2 to SO3 was inhibited in SiCe mixed catalyst.The addition of SiO2 could promote the decomposition of cerium sulfate,which may be a potential strategy to enhance the resistance of SO2 poisoning over CeO2-modifed catalysts.

Effect of water vapor on NH_3–NO/NO_2 SCR performance of fresh and aged MnO_x–NbO_x–CeO_2 catalysts

A MnOx-NbOx-CeO2 catalyst for low temperature selective catalytic reduction（SCR） of NOx with NH3 was prepared by a sol-gel method, and characterized by NH3-NO/NO2 SCR catalytic activity, NO/NH3 oxidation activity, NOx/NH3 TPD, XRD, BET, H2-TPR and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy（DRIFTS）. The results indicate that the Mn Ox-Nb Ox-CeO2 catalyst shows excellent low temperature NH3-SCR activity in the temperature range of 150-300℃. Water vapor inhibits the low temperature activity of the catalyst in standard SCR due to the inhibition of NOx adsorption. As the NO2 content increases in the feed, water vapor does not affect the activity in NO2 SCR. Meanwhile, water vapor significantly enhances the N2 selectivity of the fresh and the aged catalysts due to its inhibition of the decomposition of NH4NO3 into N2O.

Effect of MoO_3 on vanadium based catalysts for the selective catalytic reduction of NO_x with NH_3 at low temperature

The selective catalytic reduction （SCR） activities of the MoO3 doped V/WTi catalysts prepared by the incipient wetness impregnation method at low temperature were investigated. The results showed that the addition of MoO3 could enhance the NOx conversion at low temperature and the best SCR activity was obtained when the dosage of MoO3 reached 5 wt.%. The NH3-TPD and DRIFTS experiments indicated that the addition of MoO3 changed the type and number of acid sites on the surface of catalysts and reaction activities of acid sites were altered at the same time. The redox capacity and amount of active oxygen species got improved for V3Mo5/WTi catalyst, which could be confirmed by the H2-TPR and transient response experiments. Water vapor inhibited the NOx conversion at low temperature. Deposition of ammonium sulfate or bisulfate might be main reason for the loss of catalytic activity in the presence of SO2 at low temperature. Choosing the suitable NH3/NO ratio and elevation of reaction temperature both could weaken the influence of SO2 on the SCR activity of the V3MoSAFTi catalyst. Thermal treatment of the deactivated catalyst at 350℃ could get the low temperature activity recovered. The decrease of GHSV improved the deNOx efficiency at low temperature and we speculated that the rational technological process and operation parameters could contribute to the application of this kind of catalysts in real industrial environment.