Effect of rare earth addition on Cu-Fe/AC adsorbents for phosphine adsorption from yellow phosphorous tail gas

Phosphine(PH3) is a highly toxic air pollutant,commonly produced in phosphorous chemical industry.But it has received less research attention due to its handling difficultly.CO is the main content of the phosphorous chemical industry tail gas,the concentration of which is always more than 80 vol.%,and it can be the feed gas to produce various valuable products such as formate,oxalate,and methanol and so on.But,PH3 is one of the important barriers,which is harmful to the following chemical process.In order to make use of the tail gas,PH3 should be removed firstly,and CO should be covered in the whole purified procedure at the same time.In this work,the modified activated carbon(MAC) was used as the adsorbent to separate PH3 from the mixture tail gas.Series of MAC adsorbents were prepared for the adsorption of PH3,which loaded Cu-Fe and Ce(La),or separately.The PH3 adsorption capacities,chemical and physical properties of MAC were all investigated.The results showed that over 99% PH3 adsorption efficiency was achieved when used MAC adsorbents.The removal efficiency and PH3 adsorption capacity of the Cu-Fe-Ce/AC(20:1:0.4) were both much higher than those modified activated carbons.The maximum PH3 adsorption capacity was 71 mg of PH3/g of MAC on the Cu-Fe-Ce/AC,which were much higher than literature data using CuO only for adsorbing hydride gases.     

Effect of zinc and cerium addition on property of copper-based adsorbents for phosphine adsorption

A series of copper-based activated carbon (AC) adsorbents were prepared in order to investigate the effect of Zn, Ce addition on Cu-based AC adsorbent for phosphine (PH3) adsorption removal from yellow phosphorous tail gas. N2 adsorption isotherm and X-ray diffrac-tion (XRD) results suggested that the addition of Zn could increase the adsorbent ultramicropores, decrease the adsorbent supermicropores and the adsorbent average pore diameter. Therefore it enhanced the PH3 adsorption capacity. Appropriate amoun...     

稀土添加量对TiC基钢结硬质合金性能的影响

采用真空烧结法以TiC粉、纯Mo粉、纯Cr粉、羰基Fe粉、鳞片状石墨等为原料,制备了TiC基钢结硬质合金,并采用含Ce的环烷酸稀土作为成形剂,通过加入不同含量的Ce元素对其进行改性。利用SEM、万能实验机、洛氏硬度计等对烧结试样进行显微组织和性能分析。结果表明,添加稀土元素进行改性后的合金试样接近全致密;同时,TiC更加均匀地分布于基体中;添加Ce元素质量分数为0.2%时,合金抗弯强度达到最大值,相比不含Ce的合金试样提高近28%。     

Effect of rare earth addition on structure and properties of Ni-P coating on SiCp/Al composites

The aim of this work was to improve the properties of Ni-P coating on SiCp/Al composites. The effect of rare earths addition on Ni-P coating structure was investigated by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and electrochemistry methods. The results showed that as Y or La concentration was 0.15 g/L in plating solution, the highest value of deposition rate of Ni-P coating was found. And the structure of the obtained coating was modified...     

Effect of rare earth addition on continuous heating transformation of a high speed steel for rolls

The effect of rare earth(RE) on continuous heating transformation of a high speed steel for rolls was investigated by using differ-ential scanning calorimetry(DSC) with combination of microstructure analysis.Determination of the Ac1 and Ac3,the starting temperature of carbide dissolution and melting upon heating,the enthalpy change for the α→γ transformation and overall carbide dissolution were also es-tablished.It was found that RE could reduce the volume fraction of large eutectic carbides and the chrysanthemum-like eutectic colonies but could not change the phase composition.RE made a little change to Ac1,but the variation in Ac3 and enthalpy for the α→γ followed an in-creasing pattern as the RE addition increased.The start temperatures of carbides dissolution increased with increase of RE addition,which may be associated with the influences of RE on the morphology of carbides,but the overall enthalpy change of carbides dissolution decreases as the RE addition increased.Moreover,the start temperature of melting also increased with increasing RE addition.     

碱熔预处理对废旧稀土荧光粉中稀土提取的影响

针对废旧稀土荧光粉特性,采用高温碱熔与酸浸相结合的方法处理废旧稀土荧光粉,考察碱熔温度、氢氧化钠用量、碱熔时间对稀土浸出率和铝回收率的影响,并对碱熔过程中的物相及形貌变化进行分析.结果表明,在碱熔温度为1050℃、氢氧化钠与废粉质量比为2.5∶1、碱熔时间为2 h 条件下,其稀土浸出率可达98%以上,铝回收率可达98%.通过对碱熔产物物相和形貌分析表明,废粉晶体结构被有效破坏,其中稀土以稀土氧化物形式存在,碱熔产物变成无定型云絮状.     

Effect of rare earth elements addition on thermal fatigue behaviors of AZ91 magnesium alloy

Influences of rare earth (RE) elements addition on thermal fatigue behaviors of AZ91 alloy were studied. Repeated heating and cooling cycles were applied on the samples at 170 and 210 ℃ to develop thermal fatigue cracks. Crack growth mechanisms and microstruc-tural influences were investigated by optical and scanning electron microscopy (SEM) as well as energy dispersive X-ray spectroscopy (EDS). Thermal fatigue behaviors were observed to improve successively by addition of the RE up to 2wt.%. This improvement was attrib-uted to the consummation of aluminum in melt by precipitation of the needle shaped A11IRE3 phases. This process was attributed to the re-duction of Mg17Al12 phase volume fraction and consequent decrease of the brittle Mg/Mg17Al12 interface which was the main reason for weak thermal properties of the alloy at rather high temperatures. Further additions of RE, however, reduced the thermal shock resistance of the samples by increasing the mean length of the brittle needle shaped phases.     

Effect of rare earth addition on microstructure and corrosion behavior of plasma nitrocarburized M50NiL steel

M50NiL steel was plasma nitrocarburized at 480 °C with and without rare earth(RE) addition. The microstructures of the surface layer were characterized by optical microscopy, X-ray diffraction and scanning electron microscopy. The mechanical properties and corrosion resistances of the surface layer were studied by Vickers microhardness measurements and polarization tests in 3.5% NaC l solution. The results showed that RE atoms could diffuse into the surface layer of the steel and inhabit the formation of ε-Fe_(2–3)(N,C) phase. As compared to the treatment without RE addition, RE addition further increased the surface hardness by 143 HV0.1, and further increased the thickness of the nitrocarburized layer by 39 μm. Compared with the quenched bearing steel, the corrosion resistance of the samples nitrocarburized with and without RE addition could be significantly improved. Especially, the sample plasma nitrocarburized with RE addition exhibited the highest corrosion resistance.     

Effect of rare earth addition on microstructural, mechanical and electrical characteristics of Cu-6%Fe microcomposites

Cu-6%Fe (mass fraction) microcomposites containing (0-0.30)% rare earth elements were prepared by cold drawing and intermediate heat treatments. Microstructure was observed, and mechanical properties and electrical conductivity were measured for alloys at various drawing strain levels. Adding rare earth elements could reduce the size of primary Fe and Cu dendrites of Cu-6%Fe. Ultimate tensile strength increased but electrical conductivity decreased with the increase of drawing strain. Rare earth additions in Cu-6%Fe slightly increased the strength at low strain and effectively improved the conductivity at high strain. Both strain hardening rate and conductivity loss of Cu-6%Fe containing rare earths were reduced at lower strain than Cu-6%Fe.     

Effect of rare earth on the performance of Ru/MgAl-LDO catalysts for ammonia synthesis

A series of MgAl-layered double oxides (LDO) doped with different rare-earth elements (Y, La, and Ce) were synthesized by the calcination of Mg–Al layered double hydroxides, and Ru, which were used to prepare ammonia synthesis catalysts. The as-obtained oxides and catalysts were characterized by XRD, TEM, TPD, TPR and XPS to understand their catalytic performances in ammonia synthesis. The H₂-TPR and HRTEM studies reveal that Ru/Y-LDO catalyst possesses more active Ru metal and small particle size. The XPS demonstrates that the electronic interaction between Y and Ru metals is stronger, which can be tentatively explained by most of Y inserted into the hydrotalcites structure. CO₂-TPD demonstrates that Ru/Y-LDO catalyst shows stronger basic site densities than catalysts doped with Ce and La. Higher activity of the Ru/Y-LDO catalyst can be attributed to smaller particle size, more active metal (Ru) and strong Ru–support interaction.     

Effects of rare earth metal addition on microstructure of hot-dip 55%Al-Zn-Si coatings

Optical microscope(OM),scanning electron microscope(SEM),energy dispersive spectrometer (EDS) and X-ray Diffraction(XRD) were used to study the effects of rare earth on the microstructural characteristics of 55%Al-Zn-1.6%Si hot -dip coatings on steel.The results of OM,SEM and EDS showed that by adding RE into the 55%Al-Zn-1.6%Si bath,the saw-toothed shape of intermetallic reaction layer of coating became smooth,and the thickness of the overlay and intermetallic reaction layer decreased.The XRD results re...     

稀土在甲烷部分氧化制取合成气中的应用研究

稀土（La,Ce,Pr,Nd等）通常可以作为催化剂载体、助剂或与其它元素形成固溶体,成为催化剂的重要组成部分。文中系统地介绍了稀土在甲烷部分氧化（CPOM）制取合成气中的相关应用,重点分析了稀土作为催化剂载体、助剂、固溶体等在催化部分氧化制取合成气中的应用,并对其在CPOM中未来前景做出展望。     

Effect of rare earth on primary carbides in H13 die steel and their addition method:a review

Larger-sized primary carbides lead to stress concentration during the application of H13 hot-work die steel,resulting in microcracks and fatigue failure.Rare earth was usually added to modify the carbides and inclusions.The existing literature is reviewed on the effect of rare earth on primary carbides in H13 steel.A comprehensive review on the effect of rare earth on the characteristics of primary carbides,i.e.,number,size,morphology,and thermal stability in H13 steel,was done.The precipitation mechanism and nucleation of primary carbides with rare earth were summarized.The position and form of rare earth in steel and their effects on alloying elements segregation were reviewed.The addition techniques of rare earth in H13 steel were compared,and the prospects for other uncommon rare earth and emerging technology were present.Based on the current references,it can be known that adding rare earth facilitated refined and dispersed primary carbides.The size of primary carbides would be reduced,and their morphology would be improved because the rare earth inclusions formed in H13 steel can act as nucleation cores for γ-Fe or δ-Fe,refining the dendritic structure.Besides,the number of primary carbides at grain boundaries would be significantly reduced.However,rare earth had little impact on thermal stability.The nucleation of primary carbides tended to be inhibited due to the modification of inclusions by rare earth which were likely to be nucleation cores for primary carbides.Rare earth had been reported to affect the mechanism and process of primary carbide precipitation.Additionally,the addition of rare earth can inhibit the segregation of alloying elements and carbon diffusion by calculation.Thus,laboratory experiments and theoretical calcu-lations need to be conducted to study the states and evolution of rare earth steels.     

Effect of rare earth oxides on the properties of bio-soluble alkaline earth silicate fibers

Using natural mineral wollastonite, talc and quartz sands as raw materials, rare earth oxides(La_2O_3, Nd_2O_3 and Y_2O_3) as additives, the bio-soluble alkaline earth silicate fibers were prepared by melting and blowing process. The viscosity of the molten materials, bio-solubility and crystallization behavior of the fiber were investigated. The results indicated that the fiber drawing temperature range could be broadened since the slope of the temperature-viscosity curve decreased with adding rare earth oxide. The addition of rare earth oxide was beneficial to the increase of crystallization temperature by strengthening the network structure of the fiber. The existence of rare earth oxide in the fibers would reduce the solubility of the fibers, which still belonged to bio-soluble fibers.     

Effect of the structure of carbon adsorbents on the adsorption of gold cyanide

Research investigations on the chemistry of the adsorption of gold cyanide on activated carbon have mostly reduced the role of activated carbon as the provider of the large surface area needed for adsorption. Most do not go beyond suggesting that oxygen functional groups on carbon play a key role in the adsorption process. Our research shows that the nature of the material, specifically its structure, is a crucial factor in the adsorption equation. To delineate the effect of adsorbent properties, gold cyanide was adsorbed on a series of carbonaceous adsorbents, including lignite, coals, anthracites, carbon blacks, graphite and activated carbon, which covers wide variations of composition, surface acid group content, and degree of graphitization. The results show that the adsorption of gold cyanide per unit area of adsorbent is not related to the amount of oxygen groups on the surface or even the total oxygen content of the material. However, they show very strong correlation with the degree of graphitization of the adsorbent, which indicates that the graphitic plates of activated carbon play the most important role. The findings suggest that majority of the adsorption occurs on the plate faces of the graphite crystallites of activated carbon.     

Effect of impurity ions on preparation of novel saponifier for rare earth extraction

Magnesium bicarbonate,prepared by the carbonation of magnesium hydroxide slurry,was used as a novel saponifier to eliminate the ammonia nitrogen pollution in the rare earth extraction separation process.The effect of impurity ions introduced by system on the carbonation reaction of magnesium hydroxide was studied in the work.The results showed that the presence of Ca2+ could lead to side reactions so as to reduce the conversion rate of magnesium hydroxide,and a small number of rare earth ions would have great influence on the carbonation reaction.What’s more,there was no influence on carbonation reaction with the low concentration of Na+or Mg2+,the conversion rate of magnesium hydroxide could reach above 96%.This paper showed a practical theory which could provide scientific guidance for the preparation of novel saponifier in rare earth extraction separation process.     

Effect of rare earth and other cationic promoters on properties of CoMoN_x/CNTs catalysts for ammonia decomposition

Carbon nanotubes(CNTs)supported Co-Mo nitride catalysts were prepared by incipient-wetness impregnation method and temperature-programmed reaction in N2-H2 mixed gases.The effects of cationic promoters(K,Ba,La,Ce and Zr)on the catalytic performance and surface properties were investigated.All samples were characterized by N2 physical adsorption,X-ray diffraction,and temperature-programmed reduction of H2.The results showed that the addition of promoters reduced the crystallite size of Mo2N and Co3Mo3N species and increased their surface area and dispersion.Among the catalysts,the La promoted CoMoNx/CNTs catalyst had the highest ammonia conversion which could reach 97.63% at 600 oC.     

Effect of rare earth on the coating-forming and mechanism of phosphatization

It was ascertained that when a RE element was added in bath, the sample was improved on the anti-corrosion power of the coating because of the increasing of covering rate of formless crystal Zn₂Fe(PO₄)₂·4H₂O (marked P) crystals and the ratio of P/(P+H) (H was the mark of Zn₃(PO₄)₂ crystal) in the coating, combination of which with components parsing by EDS indicated that the sequence of contribution elements P and Zn to erosion resistance of coatings was P>Zn. And the correlative mechanism was discussed, which made it clear that owing to the particularity of the outer-shell electron structure and larger ionic radius, RE was so easy to be polarized and metamorphosed itself that it adsorbed lightly on the basic body to pose gels. They efficiently reduced the activation energy which was required for formation of a new solid phase of phosphates and made it also possible to engender effectively active nucleation regions of cathode and anode under low temperature phosphating condition, which was propitious to formation, densification and uniformization of the phosphate crystal nucleus and growth of the crystallite and coating buildup. Thus it could be seen that REN played the role of surface regulator and accelerant, which speeded up the phosphating, as well as bids amount of porosity of the coating fall to improve the corrosion resistance of the coating.     

Study on alkali mechanical activation for recovering rare earth from waste fluorescent lamps

Recycling of rare earth from waste fluorescent lamps is becoming increasingly important in future sustainable development. However, cerium and terbium are usually difficult to recover due to the stable spinel structure. In the research, alkali mechanical activation was innovatively used to pretreat the waste phosphors for recovering rare earths. The effect of alkali mechanical activation on the structural changes of waste phosphors was explored using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Meanwhile, the effects of different parameters including milling speed, activation time, and amount of alkali on the leaching rates of rare earth were investigated. The rare earth elements recovery rates are observed to increase rapidly, particularly with increases in rotational speed and activation time. Under optimal conditions, the maximum leaching rates of Ce and Tb reach 85.0% and 89.8%, respectively. And the total recovery rates of rare earth reach 95.2%. All the results indicate that alkali mechanical activation can effectively destroy the spinel structure and produce substantial physicochemical changes. These changes lead to the easy dissolution of rare earths in acid solution, and greatly improve the leaching of cerium and terbium.     

稀土元素的添加对原位生成的Ti-TiC-TiB复合材料抗磨损性能的影响

采用Ti 6Al 4V 5B4C和Ti 6Al 4V 5B4C 1Nd 两种成分的原始粉末, 反应热压后原位生成了Ti TiC TiB复合材料。经过X射线检测, 证明了试验中原位生成反应5Ti+B4C 4TiB+TiC的进行。采用摩擦磨损试验机检测了两种材料的抗磨损性能。通过扫描电子显微镜和电子探针分析了材料的磨损表面。结果表明, 添加稀土元素能提高材料的硬度, 韧性和抗磨损性能。