Abstract: The present invention provides a method for producing a biofuel that allows an animal/vegetable fat/oil raw material containing a free fatty acid to react with a lower alcohol in the presence of a solid acid catalyst, in which the consumption of the lower alcohol is reduced and the free fatty acid and the lower alcohol are selectively esterified to reform the animal/vegetable fat/oil. In this method, as a solid acid catalyst is used a catalyst selected from an SiO2/Al2O3 solid acid catalyst, an SiO2/Al2O3 solid acid catalyst with aluminum being partially introduced into mesoporous silica, an Al2O3/B2O3 solid acid catalyst, and a sulfated zirconia solid acid catalyst, with a molar ratio of the free fatty acid and the lower alcohol of 1 to 6.

Abstract: The present invention provides a method for producing a biofuel that allows an animal/vegetable fat/oil raw material containing a free fatty acid to react with a lower alcohol in the presence of a solid acid catalyst, in which the consumption of the lower alcohol is reduced and the free fatty acid and the lower alcohol are selectively esterified to reform the animal/vegetable fat/oil. In this method, as a solid acid catalyst is used a catalyst selected from an SiO2/Al2O3 solid acid catalyst, an SiO2/Al2O3 solid acid catalyst with aluminum being partially introduced into mesoporous silica, an Al2O3/B2O3 solid acid catalyst, and a sulfated zirconia solid acid catalyst, with a molar ratio of the free fatty acid and the lower alcohol of 1 to 6.

Abstract: Nickel, Ni, of 5 to 10 mass %, silicon, Si, of 0.5 to 5 mass %, manganese, Mn, of 0.01 to 1 mass %, carbon, C, of 0.2 to 2 mass % and a remaining part consisting of iron, Fe, and incidental impurities are employed, and further chromium, Cr, of 1 to 10 mass % is added to obtain a martensitic cast steel material for which a martensitic transformation finish temperature (Mf point) is below freezing. Further, a cast steel material that contains vanadium V of 0.1 to 5 mass % in addition to the above elements of the material is also obtained. For these cast steel materials, since martensitic transformation occurs merely by performing a sub-zero treatment, the tempering process can be comparatively easily performed, and machining in a desired shape is easily performed.

Abstract: To improve corrosion resistance in wet environments, for a martensitic cast steel material obtained at a predetermined composition ratio and martensitic steel casting products, and to provide a martensitic cast steel material that is appropriate for various types of molds and dies, mechanical parts, etc., and a manufacturing method for martensitic steel casting products. Nickel, Ni, of 5 to 10 mass %, silicon, Si, of 0.5 to 5 mass %, manganese, Mn, of 0.01 to 1 mass %, carbon, C, of 0.2 to 2 mass % and a remaining part consisting of iron, Fe, and incidental impurities are employed, and further chromium, Cr, of 1 to 10 mass % is added to obtain a martensitic cast steel material for which a martensitic transformation finish temperature (Mf point) is below freezing. Further, a cast steel material that contains vanadium V of 0.1 to 5 mass % in addition to the above elements of the material is also obtained.