Molten salt method

Solution processes for removal of SO2 from effluent gas streams normally require lower absorption temperatures than do gas phase techniques. Thus, of the four listed in Table IV only the Molten Salt Method has the capability of accepting high temperature flue gas without cooling. In all but one of the cases, elemental sulphur is the end product and in the single instance of the Ammoniacal Solution Process, sulphur is a coproduct with ammonium sulphate. This process has been extensively examined and developed in a number of countries, and is chemically interesting because of the unusual redox reaction that is suspected to take place between the products of air oxidation of SO2 absorbed in ammonia solution. Both products, sulphur and ammonium sulphate, are normally saleable commodities. 

Zeolite-supported Ni and KNiCa catalysts were prepared by molten-salt method [2], which were designated as Ni/ZSI and KNiCa/ZSI, respectively, hereinafter. The support was a high siliceous ZSM-5 zeolite (UOP S-115) mixed with an alumina. 

Cheng, L., H. J. Liu, J. J. Zhang, H. M. Xiong, and Y. Y. Xia. 2006. Nanosized Li4Ti50i2 prepared by molten salt method as an electrode material for hybrid electrochemical supercapacitors. Journal of the Electrochemical Society 153 A1472-A1477. 

Tilquin, J.Y., J. Fournier, D. Guay, J.P. Dodelet, and G. D6nSs (1997). Intercalation of C0CI2 into graphite Mixing method vs. molten salt method. Carbon 35, 299-306. 

Gopalan S and Wkar A V (1993), Thermodynamic stabilities of SrCe03 and BaCe03 using a molten salt method and galvanic cells ,/ Electrochem Soc, 140,1060-1065. 

Compared with the traditional sintering method, the molten salt method is one of the simplest methods for controlling the morphology of particles and obtaining highly reactive powders of a single phase at low temperatures in a short soaking time. This is because the molten salt can accelerate the reaction kinetics at this low temperature and facilitate the formation of ceramic particles. 

Compared with the conventional method, the ceramic prepared from the molten-salt route showed better dielectric properties. Tawichai et al. [77] reported BaFeo.5Nbo 03 (BFN) ceramics that were obtained at 700 C. Because the ceramics prepared by the molten-salt method had a higher density (6.12 g/cm ) than the ceramics prepared by the traditional sintering method (4.60 g/cm ), a very high dielectric constant with low loss tangent was observed. 

Pure perovskite phase Bao.7Sro.3Ti03 nanoparticles were synthesized by the molten-salt method in NQ-KCl flux at a low temperature of 850°C. The molten salts accelerated the formation of the Bao.ySrojTiOs, and the calcination temperature played an important role in the development of BST particle morphology [79]. 

Li et al. [80] reported SrTi03 submicrmi crystallites and nanocrystals from a starting raw material of Ti02 powder (submicron or nanosized) at 700 C by an eutectic NCl-KCl molten-salt method, and found that Ti02 played an important role in the morphology and size of the obtained SrTiOa. 

No crystalline phases of doping elements was observed in the XRD patterns of the samples, either non-calcined or after the calcination at 800 C. Therefore, stable dispmed oxospecies of V, Nb, Cr, Mo, W are present in the solids prepared by the molten salt method. 

Molten salt method was previously applied for the synthesis of zirconia stabilized with yttrium and solid solutions were obtained [4]. The surface area of the product was found to be about 130 m /g, Such an yttria-stabilized zirconia was used as a catalytic support for hydrotreating catalysts. 

Park M., Choi C.L., Lim W.T., Kim M.C., Choi J., Heo N.H. Molten-salt method for the s)mthesis of zeolitic materials II. Characterization of zeolitic materials. Microporous Mesoporous Mater., 2000 37 81-89. Ramaswamy V., Tripathi B., Srinivas D., Ramaswamy A.V., Cattaneo R., Prins R. Structure and redox behavior of zirconium in microporous Zr-sUicalites studied by EXAFS and ESR techniques. J.Catal, 2001 200 250. 

The main zeolite species s5mthesised by the molten salt method were dependent on the types of salt mixture and raw material used. They concluded that the molten salt method is a new and alternative approach for the mass treatment of these mineral wastes at low cost, as well as for the improvement of the purity and alkalinity of zeoHtic materials. 

Molten salt synthesis based on the use of salts with low melting point has been reported to be one of the simplest techniques for preparing ceramic materials [57]. Well-faced LNM crystals were synthesized by molten salt technology using stoichiometric amount of LiOH, Ni(OH)2, and y-MnOOH (2 1 3) calcined at 700-1000 °C [57]. Micro-sized LNM crystals in plate and octahedral shapes were synthesized by molten-salt method in LiCl and LiCl-KCl fluxes the main surface facets on the plates were determined to be (112) crystal planes [58]. Recenfly, microscale LNM was synthesized using nanothom stmctured MnOa mixed with Li and Ni precursors [59]. 

Li Y, Nuli Y, Yang J et al (2011) MgFeSi04 prepared via a molten salt method as a new cathode material for rechargeable Magnesium batteries. Chin Sci Bull 56 386-390. doi 10. 1007/sl 1434-010-4247-4... 

Compared to the MW-assisted method [11], Bi-YIG nanopartides were successfully synthesized by the molten salt method in NaCl-KCl flux at 650 °C. XRD, SEM, dynamic light scattering, VSM, and Faraday rotation meter were used to characterize the phase, morphology, size distribution, magnetic properties, and Faraday rotation... 

Combustion in oxygen, oxidizing fusion and the molten salts method can be used to separate (66)(67)(70)(71). 

In view of the production of alkaline supernatant/waste solution after hydrothermal and fusion methods, a molten salt method has been demonstrated by previous researchers for synthesis of zeolites by employing a dry conversion technique without use of water. In tune with this, mixture of chemicals/salts and fly ash has been reported to yield zeolites by reaction of salts in molten condition for a period up to 3 days. A flow chart of the synthesis process is depicted in Fig. 3.4 [15, 16]. 

Park et al. [15, 16] have established the molten-salt method for the synthesis of zeolitic materials without any addition of water. The zeohtization of fly ash has been demonstrated by employing various mixtures of NaOH, KOH, or NH4F as mineralizers and NaNOs, KNO3, or NH4NO3 as solvent instead of demineralized water in hydrothermal method. It has been reported that zeolites like Hydroxy-sodalite and Cancrinite can get crystallized from mixture of NaOH and... 

Fig. 3.4 Flowchart of molten salt method for synthesis of zeolites...

The state-of-the-art for synthesis of fly ash zeolites from fly ash employs various chemicals like NaOH, KOH, NaaCOa, KNO3, NaNOa, NH4F and NH4NOa as weU as different techniques like hydrothermal, fusion, combination of both fusion and hydrothermal, molten salt method, microwave irradiation method. However, these methods yield final end products blended with zeolites, which comprise of some... 

Qiu et al. [22] have demonstrated a technique for removal of Lead, Copper, Nickel, Cobalt, and Zinc from water by application of a Cancrinite type zeolite synthesized from fly ash, by employing molten salt method. The degree of heavy metal adsorption has been reported to vary with the type of ion exchange... 

Ti02 prepared by the molten salt method (MSM) [308, 309]. In particular, nanosized particles obtained by urea-treated MSM delivered a reversible capacity of 250 mAh and showed a 94 % capacity retention after 60 cycles [309]. 

Reddy MV, Jose R, Teng TH, Chowdari BVR, Ramakrishna S (2010) Preparation and electrochemical studies of electrospun Ti02 nanofibers and molten salt method nanoparticles. Electrochim Acta 55 3109-3117... 

Liu B, Guo ZP, Du G, Nuli Y, Hassan MF, Jia D (2010) In situ synthesis of ultra-fine, porous, tin oxide-carbon nanocomposites via a molten salt method for lithium-ion batteries. J Power Sourc 195 5382-5386... 

Reddy MV, Yu C, Jiahuan F, Loh KP, Chowdari BVR (2013) Li-cycling properties of molten salt method prepared nano/submicrometer and micrometer-sized CuO for lithium batteries. ACS Appl Mater Interfaces 5 4361 366... 

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