Pipeline Saponification Of Lanolin And The Synthesis Of Refined Lanolin

Cholesterol is a derivative of cyclopentane polyhydrophenanthrene,which is widely used in the fields of cosmetics,medicine and liquid crystal materials.Lanolin contains more than 12%cholesterol and it’s a good raw material for the production of cholesterol.Since 1980s,studies began to study the process of preparing cholesterol by saponification of lanolin.The research focused on the selection of solvents and bases.Commonly used methods contained the monovalent alkali aqueous method,the monovalent alkali alcohol method,and the divalent alkali aqueous method,monovalent alkali aqueous plus auxiliary method and transesterification method.At present,industrial production uses lower alcohols as solvents and monovalent strong bases as catalysts.The process is mature,with problems such as long reaction time,low safety factor and limited value of by-products.In this paper,ethanol is used as the solvent and potassium hydroxide as the material to carry out continuous pipelined lanolin saponification,and the by-product lanonol and wool acid are co-produced by esterification reaction to achieve full utilization of resources and maximize economic benefits.Firstly,a batch tank reactor was used to study the effects of reaction temperature,reaction time,solvent and base types on the saponification reaction of lanolin.The study found that the reaction rate increased significantly with the increase of temperature from 80℃ to 160℃.The yield achieved at 160℃ for 1 hour is close to the result of 80℃ for 8 hours,indicating that the reaction rate could be effectively increased by increasing the temperature and reduce the reaction time.Because lanolin and low-priced strong bases have good solubility in lower alcohols,and compared with other lower alcohols,ethanol has the advantages of wide sources,low toxicity and low saturated vapor pressure at high temperatures.Therefore,ethanol was selected as the solvent.Potassium hydroxide has the advantages of strong alkalinity,high reactivity and good solubility in ethanol,and it is conducive to the subsequent calcification and separation.Therefore,potassium hydroxide was selected as the raw material base.The saponification products were separated and purified by pH adjustment,calcification precipitation,supernatant extraction and desalination.The final process conditions for intermittent kettle saponification of lanolin were as follows:m(ethanol):m(lanolin):m(potassium hydroxide)=2.5:1:0.11,the temperature was 160℃,the pressure was 1.35MPa,the reaction time was 1h,and the saponification yield of lanolin was 98.5%.Secondly,the pipeline reactor was designed and pipelined lanolin saponification process was developed.According to the properties of raw materials and reaction conditions,a stainless steel tube with an inner diameter of 4mm,a length of about 120m and made of 316L,was chosen as a tubular reactor.The influencing factors such as reaction temperature,feed rate,solvent and alkali dosage were optimized According to the experimental data,the kinetic equation of lanolin saponification was established:rA=kcAcB=8.4×106exp(-66.08/RT)cAcB,which provided reference for subsequent industrial production.The final process conditions for pipeline saponification of lanolin were as follows:m(ethanol):m(lanolin):m(potassium hydroxide)=3:1:0.11,the temperature was 160℃,the pressure was 1.40MPa,the residence time was 40min,and the saponification yield of lanolin was 99.3%.Finally,the preparation process of refined lanolin was developed.Through intermolecular reaction and thermogravimetric analysis,the reaction temperature range was 180-250℃.The factors of reaction temperature,reaction time and raw material feed ratio on the esterification process without catalysis were studied,and it was found that increasing the reaction temperature and prolonging the reaction time can increase the yield of the esterification reaction,but it would make the product darker and difficult to follow-up decolorization process.The final esterification process conditions were as follows:m(wool acid):m(lanonol):m(lanosterol)=1.1:1:0.05,without catalyst,vacuum atmosphere,react at 200℃ for 4h,heat up to 250℃ for 4h.Decolorization ability of oxidative decolorizer,reductive decolorizer and physical adsorption type decolorizer was investigated.Hydrogen peroxide and activated carbon were chosen as two decolorizers in combination.The final post-treatment process was:First of all,use 30wt%hydrogen peroxide solution for two decolorization,and then deacidify by potassium carbonate,decolorize deeply by activated carbon,and finally the product was mixed with 3 times the quality of USP grade lanolin.All indicators of the obtained mixed lanolin can meet the requirements of industry standards.