Selective hydrogenation of styrene. II. Poisoning of Pd/Al2O3 by thiophene and pyridine

The poisoning of a commercial Pd/Al₂O₃ catalyst by pyridine and thiophene during the selective hydrogenation of styrene to ethylbenzene was studied. It was found that the Pd electronic state is the main factor controlling the interaction between the metal and the poisons. Pyridine added to the non-poisoned feed in a pulse produces a modification in the Pd electronic state and a decrease in conversion, but, within certain limits, inhibits the adsorption of more pyridine or thiophene molecules.     

Selective catalytic NOx reduction on Antimony promoted V2O5-Sb/TiO2 catalyst

Quantum chemical calculation was carried out to choose a promoter which can reduce the poisoning of V2O5/TiO2 catalysts by SO2.Several atoms were chosen as candidates and new catalysts were synthesized by impregnation method.The NOx conversion rate was measured at temperatures between 100 and 400 ℃ and poisoning effect was investigated.The most promising candidate promoter, Se, was excluded because of its high vapor pressure.On the other hand, Sb shows best promoting properties.Sb promoted catalyst reaches the maximum NOx conversion rate at 250 ℃.It also shows considerably enhanced resistance to poisoning of V2O5/TiO2 catalysts by SO2.     

化学中毒及其防护

讨论了化学中毒的途径、危害、分级 ,介绍了芳香烃类、醇类、酮类等常用部分有毒溶剂的毒性。最后从生产工艺、生产设备和个人防护等 3个方面阐述了生产企业对常见有毒化学品的应用防护措施。     

Effect of A-site metal on methane combustion on 2% Pd / AMn1-x Fe x O3 (A = Ba, La, Pr; x = 0.4, 0.6, 1) perovskites

Barium, lanthanum, and praseodymium perovskites were prepared by malic acid complexation. Surface areas of the La and Pr perovskites were between 17.1 and 21.6 m² g⁻¹. The moderate low surface areas (5.7 m² g⁻¹) observed for corresponding barium perovskites were due to the high calcination temperatures. The calcination temperature also affected the shapes and sizes of the perovskite particles. According to SEM images the nanoparticles of the La and Pr perovskites were spherical, whereas those of barium perovskites were flakes. The conversion of methane increased in the order of A-site metal Ba < Pr < La. The CH₄ conversion after SO₂ treatment correlated with size of the perovskite particles: the smaller the particles the better the activity. The highest methane conversion after SO₂ treatment was achieved with lanthanum perovskite with B-site metal combination Mn_0.4Fe_0.6.     

Characterization and performance of (La,Ba)(Co,Fe)O3 cathode for solid oxide fuel cells with iron–chromium metallic interconnect

(La_0.6Ba_0.4)(Co_0.2Fe_0.8)O₃ (LBCF) is synthesized by a sol–gel method as a Cr-tolerant cathode for intermediate-temperature solid oxide fuel cells (ITSOFCs). The electrochemical performance and Cr deposition process for the O₂ reduction reaction on LBCF cathodes in the presence and absence of a Fe–Cr alloy interconnect are investigated in detail, in comparison with a (La,Sr)(Co,Fe)O₃ (LSCF) electrode. Cr deposition occurs for the O₂ reduction reaction on LBCF electrodes in the presence of Fe–Cr alloy. Very different from that observed for the reaction on the LSCF cathode, Cr deposition on the LBCF electrode/gadolinia-doped ceria (GDC) electrolyte system is very small and shows little poisoning effect for O₂ reduction on LBCF electrode. The results demonstrate that the LBCF electrode has a high resistance towards Cr deposition and high tolerance towards Cr poisoning.     

连续重整原料氮含量及再生干燥空气水含量超标原因分析及处理措施

中国石化海南炼油化工有限公司连续重整装置于2014年2月开始出现反应器温降、产氢率降低等现象,在3月10日后呈现持续下降趋势,重整生成油芳烃含量、芳烃产率大幅下降。查找分析原因,认为常减压蒸馏装置加工福蒂斯等高氮原油比例过高,造成重整原料氮含量升高;同时空压站和重整再生的空气干燥器干燥效果下降,造成重整再生烧焦空气中水含量升高,进而在重整反应-再生系统形成水、氮、氯共存环境,导致催化剂氮中毒,活性大幅降低。通过调整加工原油结构、优化原料预加氢操作、降低重整装置加工负荷和反应苛刻度、投用空压站备用空气干燥器、更换空气干燥剂等一系列措施,减少系统中氮和水等毒物的携带量,并提高重整再生注氯量等,使重整催化剂氮中毒得以有效控制并逐渐恢复活性,采取措施10天后装置运行基本恢复正常。     

煤基直接碳燃料电池硫处理工艺探索

煤炭是我国的主要能源,以燃烧煤为主的煤炭利用过程产生了大量的温室气体CO2、含硫化合物气体等。通过煤基直接碳燃料电池发电,理论热力学效率接近100%,而且可以实现CO2的零排放,是煤高效、低碳洁净利用的关键技术,其大规模推广应用却受到原煤含硫化合物引起的硫中毒的制约。通过对现有煤脱硫工艺进行分析,提出洗选→化学氧化→电化学氧化→离子液体萃取→溶剂萃取→高温固硫(PCESTO)阶段联合处理工艺对原煤进行脱硫处理,可以有效降低煤中硫含量,定向转化直接碳燃料电池中硫的存在形式,减少和消除硫对直接碳燃料电池电极的毒化作用。     

急性酒精中毒对家兔失血性休克炎症介质的影响

目的：探讨急性酒精中毒对失血性休克后早期炎症反应的影响。方法将40只健康新西兰大耳白兔按随机数字表法分为4组,每组10只,分别为对照组（A 组）、失血性休克组（B 组）、急性酒精中毒组（C 组）和急性酒精中毒合并失血性休克组（D 组）,制作相应动物模型。监测达到休克所需的放血量和恢复伤前血压的补血、补液总量,分别于休克前、休克中、休克复苏后1 h、休克复苏后3 h 测定血清中 TNF-α、IL-6、IL-10含量。结果1）D 组的放血量要小于 B 组,复苏需要更多液体;2）与 A 组比较,B 组及 D 组血清 TNF-α、IL-6、IL-10含量均显著升高（P ＜0．01）;3）与 B 组比较,D 组各观察时点血清 TNF-α、IL-6、IL-10含量均显著升高（P ＜0．05或 P ＜0．01）。结论失血性休克后早期炎症因子的表达升高,急性酒精中毒能加重炎症介质的释放。     

Isoniazid poisoning: Pharmacokinetics and effect of hemodialysis in a massive ingestion

Isoniazid is a rare overdose that causes seizures and there is limited evidence to guide treatment. We report a 20‐year‐old female migrant who presented with recurrent seizures after ingesting 25 g of isoniazid. She was treated with activated charcoal, repeated doses of midazolam for the seizures, and given multiple doses of pyridoxine (14 mg), limited by availability. She was admitted to intensive care, and 5.5 hours post‐ingestion, she was commenced on continuous veno‐venous hemodiafiltration (CVVHDF). She was extubated after 24 hours and CVVHDF was ceased 6 hours later (30 hours post‐overdose). Her renal function remained normal and her initial lactate was the highest at 2.3. She made a full recovery. Five plasma samples were collected before, during, and after CVVHDF, and isoniazid was quantified with liquid chromatography‐tandem mass spectrometry. A pharmacokinetic analysis of time‐isoniazid concentration data was fitted to a two‐compartment model with first‐order input (with fixed k_a) with the effect of CVVHDF modeled as a time‐dependent covariate. This suggested that there was initially good clearance with CVVHDF (4 times endogenous clearance), which rapidly declined within hours.     

Experimental and modelling studies of CO poisoning in PEM fuel cells

This article is an examination of the CO poisoning and cleaning (stripping) phenomenon that occur in a PEM fuel cell operating on an impure hydrogen stream such as reformed hydrocarbons or alcohols. A range of experimental results including cell polarization curves, measurements of spontaneous and transient oscillations of the anode potential and current pulsing behaviour are presented. Detailed examination of the pulsing process has shown that optimization of both the pulse width and pulse initiation potential will have an important impact on the overall fuel cell efficiency. To optimize these processes, the development of a mathematical model to understand and control the poisoning and cleaning processes is going to be important. In this paper, we have extended the model of Zhang et al. [J. Zhang, Investigation of CO tolerance in proton exchange membrane fuel cells, PhD thesis, Worcester Polytechnic Institute, June, 2004; J. Zhang, R. Datta, J. Electrochem. Soc. 149 (2002) A1423; J. Zhang, J.D. Fehribach, R. Datta, J. Electrochem. Soc. 151 (2004) A689] to include mass transfer effects. It is shown that this new model gives results that are in reasonable agreement with our experimental data.