Preparation Of Potassium Borohydride By Reactive Crystallization

Fuel cells have been applied to many sectors after half a century,especially to the automotive industry.For alkali metal boron hydride such as sodium borohydride,calcium borohydride and lithium borohydride,they can be served as high-energy fuels to boost rocket and missile.Furthermore,for the rapid release of hydrogen,safety of operation and well applicability,combining with fuel cell to replace many batteries,they can be furnished as a promising technology of hydrogen storage.For these merits,they have attracted more and more focus from researchers.The major bottlenecks lie in low efficient storage capacity,low effectiveness caused by the cycle of sodium metaborate and excessively high costs.To deal with the problem of high costs brought by the cycle of mother liquor in the Schlesinger method producing alkali metal boron hydride and lower quality for product caused by the accumulation of by-product,the process of preparation of potassium borohydride by reactive crystallization was put forward to handle mother liquor generated by the production,increase the yield of alkali metal boron hydride while producing potassium borohydride possessing economic benefits.Feasibility study for the process of preparation of potassium borohydride by reactive crystallization was carried out from the ternary phase diagram containing water,alkali metal boron hydride and hydroxide.Additionally,iodometric method from volumetric analysis,optical microscopy,Malvern Mastersizer 3000 and X-ray diffraction were employed to test the influence of various operating conditions including molar ratio,reaction temperature,keeping temperature,power input,feeding rate and keeping time on the products' properties.The result shows that,controlling the molar ratio between 1.05 and 1.10,reaction temperature 50 ?,feeding rate 0.7ml·min-1,cooling rate 10 ? ·h-1,keeping temperature 0?,keeping time between 1h and 3h,can ensure the product meet the standards of the chemical industry.This research plays a guiding role in the problem-solving of hydrolysis losses brought by the cycle of mother liquor in the Schlesinger method producing alkali metal boron hydride and high costs brought by the equipment operation while providing an actual basis for the settlement of these.