络合剂对加氢精制催化剂影响的研究进展

络合剂作为一种常用的助剂,由于其能提高加氢催化剂的性能而得到了研究者的重视。本文综述了络合剂对加氢催化剂加氢性能的影响,总结了引入络合剂后催化剂硫化行为方面的研究进展。简要介绍了络合剂的加入对金属浸渍液性质与催化剂加氢活性的影响,及采用共浸渍和分步浸渍引入络合剂时络合剂不同的作用机理。总体来看,络合剂的添加可以延迟助剂Ni(Co)的硫化,降低Mo(W)的硫化温度,进而提高Mo(W)的硫化程度,减弱活性组分与载体的相互作用,增强了活性组分的分散性,最终提高了催化剂的加氢脱硫活性。最后指出对络合剂改性的加氢脱硫催化剂在作用机理、工业催化领域等方面的研究是未来的研究方向。     

Activity and sulfidation behavior of the CoMo/Al2O3 hydrotreating catalyst: The effect of drying conditions

The influence of drying condition of the CoMo/Al₂O₃ catalyst prepared using citric acid as a chelating agent on the sulfidation behavior and on the catalytic activity to hydrodesulfurization of straight-run gas oil (SRGO) was investigated. The catalysts dried at 110, 220, 300 and 400 °C were studied using Raman, IRS and DTG techniques. The sulfidation behavior with straight-run gas oil spiked with dimethyldisulfide (DMDS) was investigated using gas chromatography (GC) with a thermal conductivity detector and GC with an atomic-emission detector for analysis of gas and the liquid phases, respectively. It was shown that the sulfidation behavior of the catalysts prepared using the chelating agents depends on the drying condition: the lower drying temperature, the later DMDS conversion and oxide precursor sulfidation starts. A higher activity in SRGO desulfurization was obtained with catalysts dried at 110 and 220 °C. This phenomenon was accounted for by the stabilization effect of chelating agent that retards precursor sulfiding but provides favorably the formation of active CoMoS phase and achieving the highest activity.     

DTC类重金属捕集剂研究的进展

二硫代氨基甲酸盐(dithiocarbamate，DTC)衍生物对重金属有极强的螯合能力，在环境治理中主要有螯合剂和螯合树脂两种利用形式。前者主要用于成分复杂污染物中重金属离子的去除；后者主要用于环境分析中金属的分离与预富集。今后进一步研究方向应为：根据物质结构与性能的关系，开发更加稳定、高效、低毒的产品，并加强其应用工艺的研究开发。     

Effect of sulfidation process on catalytic performance over unsupported Ni-Mo-W hydrotreating catalysts

Oxidic unsupported Ni-Mo-W catalysts were chosen to elucidate the effect of sulfidation conditions on the catalytic performance. The catalysts were sulfided in situ by using dimethyl sulfide as sulfiding agent. The relationships between the time needed for sulfidation and the sulfiding conditions were studied by GC-analysis method. Straight-run gas oil with high sulfur and nitrogen content was used to evaluate the hydrotreating performance. The oxidic catalyst precursors and sulfided catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). With increasing sulfiding liquid hourly space velocity (LHSV) of the sulfiding agent, the reaction time necessary for the sulfidation decreased, while the activity of the catalyst increased significantly. The higher catalytic activity might be due to the MoS₂/WS₂ slabs with shorter length and higher stacking number, which might contribute to the catalyst with more active sites. Sulfiding at 330 °C took the longest sulfidation time, while the catalytic activity was also the highest after sulfiding at this temperature. Furthermore, within a certain range, the sulfidation pressure had no evident effect on the catalytic behavior or activity. The purpose of this work was to provide a basis for actual production and a reference for further research.     

Support effects in the hydrotreatment of model molecules

The support effect on the activity of hydrotreating catalysts using model molecules was analyzed for catalysts supported on TiO₂, SiO₂ and MgO. The results reported in the literature indicate that adequate design of the characteristics of the catalytic support is of great importance in the development of better hydrotreating catalysts. It was shown that by means of an adequate support design it is possible to increase significantly the HDS, HYD and HDN functionalities of hydrotreating catalysts. Semiconducting supports like TiO₂ can improve the HDS and HYD activities by exerting electronic effects on the active phase, helping in this way the formation of sulfur vacancies. Alumina supports modified by SiO₂ can facilitate the sulfidation of the active species, leading to better-promoted type II active sites with increased HDS and HYD catalyst functionalities. The nature of the support affects the sulfidation and dispersion of the catalysts even when chelating agents are used during catalyst preparation.     

Hydrocracking ofn-heptane on a sulfided NiMo-Y zeolite catalyst: effect of the sulfidation method

The activity and the selectivity of a bifunctional NiMo sulfides-Y zeolite catalyst forn-heptane hydrocracking depend very much on the sulfidation agent, namely hydrogen sulfide, or dimethyldisulfide in solution inn-heptane orn-decane. The presence of a hydrocarbon during the sulfidation lowers the acid activity of the catalyst because of coking of the zeolite acid sites, and also decreases the hydrogenating activity, due to a poorer sulfidation of the catalyst.     

硫化条件对氧化铈高温煤气脱硫剂的影响

氧化铈是一种新型的高温煤气脱硫剂,它的主要优点是再生过程中能产生单质硫。本文采用工业硝酸铈Ce（NO3）3.6H2O为原料制取CeO2,用干混法制备CeO2高温煤气脱硫剂。在固定床反应器中考察不同空速、不同硫化温度以及水气氛对脱硫剂脱硫效率的影响。结果表明：硫化温度800℃,空速1 500 h-1脱硫剂的脱硫效率较高;水气氛的存在,抑制了脱硫剂的还原与硫化,使得脱硫剂的脱硫效率下降。     

高分子螯合剂处理含镉废水的试验研究

探讨了投药量、pH值、沉淀时间、体系温度对高分子螯合剂捕集Cd2+离子的影响.确定了该药剂处理20 mg/L含镉模拟废水最佳工艺参数为:投药量为浓度1％(m/V)的螯合剂0.7 ml,pH值为6～9,沉淀时间30 rain,比较合适的温度为30℃.     

Selectivity enhancement of Co-Mo/Al2O3 FCC gasoline hydrodesulfurization catalysts via incorporation of mesoporous Si-SBA-15

Mesoporous Si-SBA-15 was applied to enhance the FCC gasoline selective hydrodesulfurization (HDS) performance of conventional Co-Mo/Al₂O₃ catalysts and the physicochemical properties of the resulting catalyst were compared with those of Co-Mo/Al₂O₃ catalysts incorporated with macroporous kaolin, mesoporous Si-MCM-41 and microporous Si-ZSM-5. The selective HDS performances of all the catalysts were assessed with different FCC gasolines as feedstocks. The results showed that the HDS selectivity of the catalysts was closely related to the Mo sulfidation that depends on catalyst surface area and metal-support interaction. With the superior Mo sulfidation, the Co-Mo/Si-SBA-15-Al₂O₃ catalyst had the optimal HDS selectivity for not only the full-range FCC gasolines but also the heavy fractions thereof. The present article demonstrates the significance of enhancing Mo sulfidation in improving HDS selectivity and thus sheds a light on the development of highly selective HDS catalysts.     

Cathodic dissolution of the passive film on iron—II. Effect of chelating agents

The effect of chelating agent on the cathodic reduction of the passive film on iron has been studied. The results from the potentiodynamic polarization and galvanostatic reduction curves indicated that the contribution of chelating agent was to expedite the reduction of the passive film, and eventually to pick ferrous ion off metal lattice. This effect was greater in a ligand that forms more stable complex with ferrous ion.The general mechanism for the cathodic reduction of the passive film in the presence of chelating agent was proposed. The process consisted of several steps, and the rate-determining step was the electrochemical reduction of the ferric complex with chelating agent.     

Realistic Surface Science Models of Hydrodesulfurization Catalysts on Planar Thin-Film Supports: The Role of Chelating Agents in the Preparation of CoW/SiO2 catalysts

Realistic surface science models of supported molybdenum- and tungsten-based hydro-treating catalysts have been made by impregnating planar thin films of silica and alumina with aqueous solutions of the normally utilized precursor salts of active elements. These models have enabled detailed studies of catalyst preparation and hydrodesulfurization kinetics. Optimization of the catalysts is possible by applying appropriate chelating agents for the promoting elements cobalt and nickel. These complexes work by stabilizing the promoting element such that during sulfidation MoS₂ and WS₂ structures form before the promoters are released so that these have a higher chance to end up at the edges of MoS₂ and WS₂ instead of forming the less active Co₉S₈ and Ni₂S₃ phases. The extent to which sulfidation of the promoter cobalt is delayed correlates with the activity of the catalyst for thiophene hydrodesulfurization.     

超临界CO2配合萃取中药中重金属的研究进展

综述了国内外采用超临界流体技术配合萃取中药中重金属的研究现状。介绍了中药中重金属的形态分析方法、重金属的存在形态与配合萃取的关系、超临界配合萃取的原理、配合剂的选择和回收利用、配合萃取过程的影响因素等。提出了有关于中药中微量重金属的化学形态、寻找合适的配合剂、超临界条件下配合萃取本身的机理等几个目前存在的问题,并对今后的研究趋势进行了展望。     

钼基加氢催化剂硫化研究进展

钼基加氢催化剂的硫化过程和硫化程度对催化剂活性影响较大,从硫化方式、硫化剂、硫化过程和硫化机理等方面综述了钼基加氢催化剂的硫化研究状况,指出钼基加氢催化剂的硫化研究面临的问题,并对钼基加氢催化剂的发展前景进行展望。     

危险化学品事故应急洗消产品研究

针对强酸强碱等化学品喷溅或泄漏引起灼伤事故,开发一种能与酸、碱、氧化、还原、溶剂化、螯合反应的两性螯合剂,并研制出化学品灼伤现场急救的洗消产品。对自制洗消剂和法国普利沃公司生产的敌腐特灵进行家兔皮肤酸碱洗消实验,结果表明,该洗消剂和敌腐特灵的酸碱洗消效果相当,具有明显的酸碱中和作用,对化学污染皮肤保护作用显著,可明显减少创面损伤,使用后创面可较快愈合。     

D403螯合树脂及其在烧碱装置中的应用

与日本CR-10螯合树脂比较,讨论了D403螯合树脂的性能,重点介绍了D403螯合树脂在锦化集团氯碱股份有限公司的应用情况.     

Towards understanding the microstructures and hydrocracking performance of sulfided Ni–W catalysts: Effect of metal loading

Detailed structural characterization of Ni–W hydrocracking catalysts with different metal loading were investigated before and after sulfidation by XRD, NH₃-TPD, TPR, XPS and HRTEM, then their catalytic performances were examined by hydrocracking of n-dodecane. Increasing metal amount would lead to the increase in sulfidation of W phase and Ni phase, WS₂ slab length and stacking WS₂, the metal–support interaction became weaker and the reducibility of catalyst was improved, therefore, catalytic activity increased and reached an optimum at about 30 wt.% total metal oxides. Further increase in the metal content would lead to the multiple layer metal distribution and increasing WS₂ slab length and slab stacking degree to a higher extent, which would result in the decrease of metal active site at edge and corner site of WS₂ slabs, and finally decrease the catalytic activity.     

聚合松香洗涤脱色条件的探讨

考察了不同的化学试剂、温度等对聚合松香汽油溶液洗涤效果的影响。结果表明,饱和草酸溶液和金属离子鳌合剂溶液具有较好的洗涤效果。工厂生产性实验结果表明金属离子鳌合剂溶液洗涤能使聚合松香色泽降低1个加纳色号。     

Removal of Heavy Metals from a Chelated Solution with Electrolytic Foam Separation

Abstract

An experimental study was conducted on the chelation and electrolytic foam separation of trace amounts of copper, nickel, zinc, and cadmium from a synthetic chelated metal wastewater. Sodium ethylenediaminetetraacetate (EDTA), citrate, sodium diethyldithiocarbamate (NDDTC), and potassium ethyl xanthate (KEtX) were used with sodium dodecylsulfate (NaDS) as a foam-producing agent. Experimental results from an electrolytic foam separation process showed that chelating agents NDDTC and KEtX, due to their higher chelating strength and hydrophobic property, can efficiently separate Cu and Ni from chelated compounds (Cu, Ni/EDTA, and Cu, Ni/citrate). In a Cu-EDTA-NDDTC system with a chelating agent/metal ratio of 4, the residual Cu(II) concentration is 0.7 mg/L. The effects of chelating agent types and different chelating agents concentrations on the removal of metal ions were studied. The effect of NaDS dosage on flotation behavior and the efficiency of metal removal were also investigated.     

钼/活性炭渣油加氢催化剂的硫化

钼/活性炭催化剂是一种新型渣油加氢催化剂,其硫化效果直接决定着催化剂的活性和稳定性。实验考察了硫化条件对钼/活性炭催化剂（Mo/AC）硫化度的影响,运用X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和透射电镜（TEM）等手段对硫化态催化剂进行了表征。结果表明,以二硫化碳为硫化剂,正十六烷为硫化介质,在硫化温度350 ℃,硫化时间3 h,氢气初压6 MPa条件下催化剂硫化度为85%,活性相MoS2堆垛结构为4～6层,晶片长度为6～10 nm,分布比较均匀,具有良好的加氢活性。     

丙烯酸改性沥青车底涂料

介绍丙烯酸改性沥青车底涂料的制备工艺 ,探讨了聚合工艺对乳液的影响以及乳液种类、偶联剂对涂料性能的影响。其结果 :以互穿网络乳液制得的涂料有较好的防石击性和阻尼性能 ;偶联剂用量为 1%时 ,涂料的力学性能较好。