Phytosterol Crystallization Separation Of The Refining Process And The Esterification Process

Phytosterol is ond kind of important steroids. It can be mainly obtained from waste oil of refining vegetable oil especially from deoderizer distillate (DD oil). Phytosterol is widely applied in the biochemical, pharmaceutics and cosmetic industry. The pure single phytosterol was purified and separated from phytosterol mixtures which were obtained from deoderizer distillate by the solvent crystallization method. The esterification process of stigmasterol, B-sitosterol and phytosterol mixtures were studied in order to separate and purify phytosterol mixtures by the combination of reaction and crystallization. The research results provide theorical basic and technological parameter for the industrialization of the process. The main research works were as follows:1. Purifying and separating phytosterols by crystallization method (1) The solubilities of phytosterols in organic solvents and the three-phase pharm of stigmasterol/B-sitosterol/solventThe solubilities of phytosterols in organic solvents were determined under room temperature. Cyclohexanone, n-butanol and n-pentanol all could be selected as solvents to purify and separate phytosterol mixtures by crystallization method. The solubilities of B-sitosterol and stigmasterol in cyclohexone or n-pentanol were determined respectively at different temperature further. The phase diagrams of stigmasterol /B-sitosterol/cyclohexanone (or n-pentanol) at 25C and 60C were determined in order to predict theoretical result in the experiment. The experimental results show that the solubility of B-sitosterol in cyclohexanone or n-pentanol is larger than that of stigmasterol in the same solvent at the same condition; the solubility of B-sitosterol increases much faster with temperature in cyclohexanone than that of stigmasterol.(2) The processes of purifying and separating phytosterol mixtures by recrystallization and fractional crystallization methodsThe content of stigmasterol is more than 92% after five stages crystallization in n-pentanol or cyclohexanone. And the content of B-sitosterol is more than 87% after the three fractional crystallizations in cyclohexanone. The processes of purifying stigmasterol and B-sitosterol were investigated, the content of stigmasterol and B-sitosterol were determined by FT-IR and Uv-vis spectroscopy analysis method. 2. The studies on the esterification process of phytosterol(1) The reaction between phytosterol and excess acetic acid solutionThe esterification kinetics of stigmasterol, B-sitosterol, brassicasterol and campesterol in excess acetic acid solution were determined under reflux condition. The effects of strongly acidic styrene cation exchangers as a catalyst and the content of water on the reaction kinetics and esterification results were also studied. In addition, the process of preparation for phytosterol acetate was discussed, and the thermodynamic properties of esterified products were also determined. The experimental results show that the rate equation of esterification for four sterols with acetic acid under reflux conditions are nearly same and could be expressed as r=(0.278 +0.002)xC(mol . L-1 . h-1); the effect of the catalyst in the presence of 2.5% to 5.0% (by mass) on the rate constant is below 5%; the rate constant of k decreases from 0.215h-1 to 0.105h-1 when content of water varying from 3.0% to 15.0% by volume.(2) The reaction between phytosterol and acetic anhydrideThe acetylation of phytosterol was studied and the effects of reaction temperature, reaction time, and reactant mass ratio on esterifying results were investigated. The product was characterized by FT-IR, HPLC and DSC methods. The experimental result show that the acetylization conversion of phytosterol could be more than 95.0% under the conditions of phytosterol and acetic anhydride based on the mass ratio of 1:10.0 at 90C for 0.5h; the yield of phytosterol could be above 92.0%.(3) The reaction between phytosterol and succinic anhydrideThe hemisuccination of B-sitosterol and succinic anhydride was studied. The proces...