The capture of carbon dioxide by transition metal aluminates,calcium aluminate,calcium zirconate,calcium silicate and lithium zirconate

The capture of CO₂ by transition metal (Mn, Ni, Co and Zn) aluminates, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate was carried out at pre- and post-combustion temperatures. The prepared metal adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface area analysis and acidity/alkalinity measurements. The different experimental variables affecting the adsorbents ability to capture CO₂, such as the mol ratio of metal ions, the pressure of CO₂, the exposure time and the temperature of the adsorbent were also investigated. Calcium zirconate captured 13.85 wt-% CO₂ at 650°C and 2.5 atm and calcium silicate captured 14.31 wt-% at 650°C. Molecular sieves (13X) and carbon can only capture a negligible amount of CO₂ at high temperatures (300°C–650°C). However, the mixed metal oxides captured reasonable amount of CO₂ at these higher temperatures. In addition, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate adsorbents captured CO₂ at both pre and post-combustion temperatures. The trend for the amount of captured carbon dioxide over the adsorbents was calcium aluminate相似文献   

苛化提纯盐湖锂矿回收含氟碳酸锂的研究

主要论述了一种提纯盐湖锂矿和回收含氟碳酸锂的方法。工艺流程：盐湖锂矿（含氟碳酸锂）通过一次水洗涤除去其中所含的大部分可溶性杂质后,按一定配比将其投入到石灰乳料浆中加热到90~95 ℃反应4 h,过滤后得到氢氧化锂溶液,将氢氧化锂溶液在100~120 ℃下进行加压浓缩4 h精制得到钙镁离子和硅含量较低的氢氧化锂溶液;向精制后的氢氧化锂溶液中通入食品级二氧化碳沉锂得到工业级碳酸锂,或继续浓缩制备氢氧化锂;用以上工艺生产得到的工业级碳酸锂通过二次碳化、阳离子交换树脂除去钙镁离子、重结晶可得到硅含量为10×10^-6以内的高纯碳酸锂,或浓缩得到钙含量为5×10^-6、镁含量为2×10^-6以内的单水氢氧化锂。     

硼酸喷雾包覆改性镍钴铝酸锂的制备及其电化学性能研究

针对镍钴铝酸锂（NCA）三元正极材料普遍存在的循环寿命差、浆料容易凝胶等缺点进行了硼酸喷雾包覆的改性。采用X 射线衍射仪（XRD）、扫描电镜（SEM）、透射电镜（TEM）及电化学测试等方法对硼酸包覆改性前后的材料性能进行了对比表征和分析。结果表明：喷雾包覆后可以在NCA正极材料表面形成一层保护层,改性后的NCA三元正极材料循环寿命有明显提升,特别是高温（45 ℃）1C/1C倍率下循环50次容量保持率由改性前的88.0%提升至改性后的95.2%,提升近7%;硼酸包覆可以改善NCA表面特性,使正极浆料稳定性大大提高。改性后的NCA正极浆料可以稳定放置168 h（7 d）,解决了NCA正极材料容易凝胶的问题。     

铝系成型锂吸附剂性能测试评价与对比

我国察尔汗盐湖卤水中蕴含丰富的锂资源,但总体品位较低,具有锂浓度低、镁锂比高的特点,导致开发难度很大。吸附法是针对高镁锂比卤水进行提锂的有效方法,其中铝系锂吸附剂具有洗脱无溶损的优势,目前已在盐湖提锂工业中应用。分别对两种工业化铝系锂吸附剂A、B以及实验室自制吸附剂C进行了系统化表征与吸附性能评价。实验结果显示三种成型吸附剂的有效成分均是锂铝层状氢氧化物,在静态吸附条件下,25℃时吸附剂A、B、C对察尔汗老卤中锂的吸附量分别为2.23、0.45、4.90 mg·g^-1,吸附动力学均符合拟二级动力学方程,不同温度下吸附等温线拟合结果表明Sips三参数模型能够准确描述三种吸附剂的吸附过程。     

低品位菱镁矿与工业铝灰制备镁铝尖晶石

以低品位菱镁矿与工业铝灰为原料制备镁铝尖晶石材料。分析讨论了不同煅烧温度对工业铝灰材料组成与微观结构的影响,并进一步研究了煅烧温度对制备镁铝尖晶石材料的组成、镁铝尖晶石相晶胞常数及材料微观结构的影响。用X射线衍射（XRD）和扫描电镜（SEM）对煅烧后试样的物相和显微结构进行研究。利用X′ pert plus软件对试样中主晶相的晶格常数进行计算,比较不同温度煅烧试样的相对结晶度。结果表明：随着工业铝灰煅烧温度的升高,材料中主晶相六方晶型的刚玉相晶胞常数呈现各向异性的变化趋势。低品位菱镁矿与工业铝灰经1 400 ℃高温煅烧可以制备出以镁铝尖晶石为主晶相的镁铝尖晶石材料,该温度煅烧的镁铝尖晶石材料晶粒相对均匀、结构相对致密,主晶相镁铝尖晶石相晶格常数最大。     

Isotope-specific analysis of neutron-irradiated lithium aluminate ceramics by nuclear magnetic resonance spectroscopy

The effects of neutron irradiation on lithium aluminate ceramics and the transport and incorporation of tritium into surrounding components are primary concerns in the development of materials for use in tritium production. The high specific activity and volatility of the tritium in activated samples greatly increase the challenges of experimental analysis. This paper reports the determination of structural forms and concentrations of ³H and ⁶Li in irradiated and nonirradiated LiAlO₂ by nuclear magnetic resonance spectroscopy. The experiments find tritium uniformly distributed in hydroxyl groups bridging aluminum centers and lithium in four- and six-coordinated sites. These results demonstrate that measurements can be performed in a nondestructive, safe manner to obtain isotope-selective, quantitative information even on highly hazardous materials.     

硅酸镁锂的有机改性及物化性质研究

以十六烷基三甲基溴化铵(CTAB)、十六烷基溴化吡啶(CPB)及十八胺(ODA)为有机改性剂,采用阳离子交换法对硅酸镁锂进行有机改性。并用小角度X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、热失重分析仪(TG)及扫描电子显微镜(SEM)对样品进行了表征;采用孔分布及比表面积测试仪测定了样品的孔分布情况及比表面积。实验结果表明3种改性试剂均插入硅酸镁锂层间,硅酸镁锂的层间距得到增大,其中十八胺-硅酸镁锂层间距增大到2.09nm;硅酸镁锂经有机改性后在有机溶剂及聚合物单体中的分散性得到提高。     

碳化法制备电池级碳酸锂工艺优化研究

碳化法因具有反应高效、工艺简单等特点,已成为电池级碳酸锂生产的主流工艺。但是,在以盐湖锂精矿为原料采用碳化法制备电池级碳酸锂的过程中,还存在碳化过程二氧化碳利用率低、碳化液杂质去除效果不好以及锂的收率低等问题。以盐湖锂精矿为原料,从碳化、净化、热解3个主要环节进行了工艺优化实验,即由常压碳化改为加压碳化、采用化学净化和离子交换树脂吸附相结合的方法去除碳化液中的杂质、由常规热解改为加压热解,可将碳化过程二氧化碳利用率提高到87.4%、净化过程钙镁去除率分别提高到97.92%和96.09% 、全流程锂的直收率提高到82.27%。     

铝基锂吸附剂制备及其在泰和地下卤水提锂中的应用

中国锂资源丰富,但是大部分存在于卤水中,提取利用困难。为提高泰和地下卤水提锂过程的效率,制备了高性能的铝基锂吸附剂。采用一步法制备了铝基锂吸附剂。通过X射线粉末衍射仪表征了铝基锂吸附剂的晶型结构。研究了加料方式、铝锂物质的量比、反应终点pH、反应温度、加料速率、搅拌转速等因素对铝基锂吸附剂吸附容量的影响。确定了铝基锂吸附剂的最佳制备条件：将氢氧化钠溶液滴加到氯化铝和氯化锂的混合液中,铝锂物质的量比为1.25∶1,反应终点pH为6~7,反应温度为75 ℃,氢氧化钠溶液滴加速率为3 mL/min,搅拌转速为100 r/min。将制备的铝基锂吸附剂应用于泰和地下卤水的提锂过程,结果显示铝基锂吸附剂的平均吸附容量高达15.06 mg/g、平均脱附容量为14.11 mg/g、脱附效率为93.69%。     

Lipid adsorption capacities of magnesium silicate and activated carbon prepared from the same rice hull

This study is a comparison of the lipid adsorption capacities of synthetic magnesium silicate and activated carbon produced from rice hulls of the same origin. The lipids examined were the free fatty acids, diacylglycerols and monoacylglycerols of frying oils. Pure oleic acid, an unused sunflower frying oil and a used sunflower frying oil were used in the experiments. The produced adsorbents, magnesium silicate and activated carbon, have surface areas of 680 and 43 m²/g, respectively. The lipid adsorption capacity of the produced magnesium silicate was found as 644 mg polar compounds/g adsorbent and it is higher than the capacities of the industrial adsorbents, Magnesol XL and activated carbon. This value is only 368 mg polar compounds/g adsorbent for the activated carbon produced from the same‐origin rice hull.     

Enhancement of ionic conductivity by mixing lithium borate with lithium aluminate

Several lithium borates (Salt A and Salt B) and a lithium aluminate (Salt C) with electron-withdrawing groups, OC₆F₅, OCOCF₃ or N(SO₂CF₃)₂, and oligoether chains (O(CH₂CH₂O)_nCH₃) directly bonded to the ate complex center, B or Al, were prepared. Lithium borate and lithium aluminate were mixed to get mix-salt electrolytes. Higher ionic conductivity was observed for the mix-salt than for the pure-salt. Conductivity as high as 1.1 × 10⁻⁴ S/cm at ambient temperature (25 °C) was achieved for the electrolyte in the optimized composition. The reason for such mixing effect on enhancement of ionic conductivity was discussed. Other electrochemical properties including electrochemical stability, compatibility with lithium anode and cyclic performance were also investigated for the mix-salt electrolytes.     

Adsorption of lithium ions on lithium-aluminum hydroxides: Equilibrium and kinetics

The rapid development of rechargeable lithium batteries has promoted the demand of primary lithium products obtained from lithium-bearing resources, especially salt lakes. Layered lithium-aluminum hydroxides connecting with ion exchange resin were used for the adsorption of lithium ions from aqueous resources. Batch experiments were conducted to determine the effects of pH, initial lithium concentration, and contact time on lithium adsorption. The optimal conditions for lithium adsorption were found to be pH = 7, and the equilibrium time is approximately 600 minutes. The selectivity experiment indicated that the adsorbent showed selectivity toward lithium ion, so the adsorbent could be used in the separation of lithium ion with other metal ions, especially the divalent magnesium ions. The experiment showed that the existence of the magnesium chloride enhanced the lithium adsorption onto the adsorbent greatly. The kinetic data were analyzed by several kinetic models, and the best result was achieved with a pseudo-second-order model. The commonly used adsorption isotherms were used to fit the experimental data by nonlinear regression. Both Langmuir and Temkin isotherm models could describe the isotherm well. The thermodynamic parameters (ΔG, ΔS, and ΔH) were also calculated subsequently and the results showed the lithium adsorption process is exothermic with the decrease of randomness. Breakthrough curves demonstrated the cyclic stability of the adsorbent and the influence of the feed flow rate. Lithium ions were effectively adsorbed from the aqueous solution by the adsorbent, demonstrating its feasibility for lithium recovery and providing the fundamental data for further column design.     

TiO2加入量对固相烧结合成镁铝尖晶石致密化行为的影响

以低品位菱镁矿和工业α氧化铝微粉为主要原料固相烧结合成镁铝尖晶石,探讨TiO2添加剂对合成镁铝尖晶石致密化行为的影响.用X射线衍射(XRD),扫描电镜(SEM)及相关分析软件对烧后试样的相组成和显微结构进行研究,以揭示镁铝尖晶石烧结致密化的过程机理.研究结果表明:添加剂TiO2与形成镁铝尖晶石的置换固溶作用是促进固相合成镁铝尖晶石烧结致密化的重要机理,阳离子空位的产生以及镁铝尖晶石的晶格缺陷,高温下有利于镁铝尖晶石的晶体发育和长大,在空间位阻效应的作用下,达到排除气孔使试样致密化的目的;随着TiO2加入量的增多,镁铝尖晶石的致密化程度也逐渐升高,能够有效的改善制品的烧结性能和显微结构.     

Effects of zirconium silicate and chromite addition on the microstructure and bulk density of magnesia–magnesium aluminate spinel-based refractory materials

Six synthesized magnesium aluminate spinel-based refractory compositions used in steel and cement applications, were prepared using a two stage sintering process at 1760 °C, starting with approximately 1:1 wt% ratio of pure magnesia and alumina with additions of zirconium silicate (0.5, 1.0 and 2.0 wt%) and chromite (2.0, 3.0 and 5.0 wt%). These compositions were investigated for effects on densification, chemical and mineralogical phases formed.     

Equilibrium and Kinetic Studies on Lithium Adsorption from Geothermal Water by λ-MnO2

The adsorption equilibria of lithium from geothermal water were investigated by using both powdery and granulated forms of λ-MnO₂ derived from spinel-type lithium manganese dioxide. Optimum amounts of adsorbents were 1.0 g adsorbent/L-geothermal water for powdery λ-MnO₂ and 6.0 g adsorbent/L-geothermal water for granulated λ-MnO₂. The adsorbents exhibited the promising adsorption capacities and their adsorption equilibria of lithium agreed well with the Langmuir adsorption isotherm model. The kinetic data of lithium adsorption have been evaluated using pseudo-first-order, pseudo-second-order kinetics models, as well as Elovich kinetic model. In addition, intra-particle diffusion model has been used for evaluating the kinetic data to evaluate the adsorption mechanism. The adsorption kinetic process was attributed to the gradual adsorption stage where intra-particle diffusion was found as the rate-controlling step.     

Calcium silicate and calcium aluminate cements for dentistry reviewed

Calcium silicate cements were identified as excellent materials for dentistry, particularly for dental procedures contacting the dental pulp or root system. Both calcium silicate and calcium aluminate cements cause the biomineralization (precipitation of hydroxyapatite [HA] phenomena and shield dental tissues from the underlying cement (a foreign body material). The cements also elute ions to stimulate cytokines that contribute to the healing of the dental pulp or in the tissue surrounding the root of a tooth. The cements serve as a foundation for other dental restorative materials. This paper reviews the cement phases, properties, in vivo reactions, and clinical benefits from the use of calcium silicate and calcium aluminate ceramic cements.     

烧结法氧化铝碳分母液制备固体铝酸钠工艺研究

烧结法氧化铝生产过程碳酸化分解工序,碳酸化分解率根据精液硅量指数和产品氢氧化铝质量要求通常控制在90%,有10%的氧化铝残留在碳分母液中,随蒸发母液的回用周而复始地流经烧结、溶出等工序,这无形增加了氧化铝的生产成本。为更好地利用碳分母液中残留的氧化铝,研究了利用碳分母液生产固体铝酸钠的工艺过程。研究结果表明,碳分母液通过彻底碳酸化分解,回收其中的固体物料,再经过焙烧,可制得固体铝酸钠产品,也即通过此方法可全部回收碳分母液中残留的氧化铝。     

Effect of particle size of hydromagnesite on properties of calcium aluminate cement bonded corundum based castables

Calcium aluminate cement was premixed with hydromagnesite having different particle sizes, as a calcium magnesium aluminate cement precursor, to investigate the influence of particle size of hydromagnesite on the volume stability and thermo-mechanical properties of corundum based castables after firing at 1550 °C. The impact of particle size of hydromagnesite on the phase composition and microstructure evolution of fired castables matrix were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results demonstrate that hydromagnesite with smaller particle size has a better volumetric stability and thermo-mechanical properties of castables, because of the more homogeneously distributed micro-pores, and smaller size MA and CA₆ resulted from the more uniformly distributed hydromagnesite in castables.     

锰系锂离子筛的制备与改性的研究进展

随着新能源电动汽车、储能产业的快速发展,确保锂资源的供给成为热点话题。锰系锂离子筛因其有对锂离子的高选择性、高吸附量、低成本等优点,在盐湖提锂方面已成为最具发展潜力的吸附剂材料之一,然而其在循环吸、脱附过程中,锰的溶损以及Jahn-Teller效应等问题会影响离子筛结构的稳定性,使吸附剂的吸附性能降低。近年来,围绕吸附性能提升,从制备方法方面进行改良的研究工作很多,可通过不同的制备方法调控锂离子筛的结构和形态。针对其存在的问题,总结了可以改善其性能的方法,包括掺杂、表面包覆以及造粒和成膜等,并在此基础上对改性锂离子筛材料在工业应用方面的发展方向进行展望,制备出高数量级循环下稳定的锂离子筛材料是未来的主要发展方向。     

Transparent magnesium aluminate spinel: Effect of critical temperature in two-stage spark plasma sintering

The discolouration of magnesium aluminate spinel caused by carbon contamination is a main drawback of fabricating transparent bodies by spark plasma sintering (SPS). In this study, a two-stage heating rate profile was used to produce transparent MgAl₂O₄ without using sintering aids by SPS at 1250°C. The effect of critical temperature (Tc), at which the heating rate is decreased, on transparency and carbon contamination was investigated: higher critical temperature resulted in higher contamination. Non-uniform densification indicated that fast heating results in a hot-zone formation in the centre of sintered pellets; the higher temperature of centre favoured reaction of graphite die with spinel and formation of disordered carbon structures in residual pores.