高熔点费托蜡色度分析及脱色研究

Research on chromaticity analysis and decolorization of high melting point Fisher-Tropsch wax

以宁煤间接液化示范装置获得的费托粗蜡为原料,采用溶剂萃取的方法获得滴熔点为70~110℃的系列高熔点费托蜡产品。为改善高熔点费托蜡的色度,研究了高熔点费托蜡的色度与滴熔点之间的关系,采用活性白土和活性炭两大类吸附剂对色度较差的110号蜡进行吸附脱色处理,筛选最佳脱色工艺条件,并通过高温模拟蒸馏、N_(2)吸脱附、傅里叶红外(FTIR)、X-射线衍射(XRD)、热重、电感耦合等离子体原子发射光谱(ICP-AES)、元素分析、核磁共振(^(13)C-NMR、^(1)H-NMR)等一系列表征测试手段,比较脱色前后高熔点费托蜡产品和吸附剂物质组成和理化性质的变化。研究结果表明,活性白土脱色效果优于活性炭,得到色度值较高的110号蜡产品其赛波特色号为+16,以残留的超细催化剂颗粒为主的无机成分和不饱和碳碳双键、含氧、氮、硫等杂原子化合物的有机成分是造成高熔点费托蜡产品色度差的原因,而高熔点费托蜡中不饱和碳碳双键氧化、键能较小烃类物质的断键,含硫、氮杂原子化合物的氧化反应等可能是造成高熔点费托蜡脱色后容易发生返色的主要原因。

A series of high melting point Fischer-Tropsch wax products with a melting point of 70-110℃were obtained by solvent extraction,using the Fischer-Tropsch crude wax obtained from the indirect liquefaction demonstration device of Ningxia coal as the raw material.In order to improve the chromaticity of the high melting point Fischer-Tropsch wax,the relationship between the chromaticity and the drop melting point of wax with high melting point was studied.Two types of adsorbents including activated clay and activated carbon,were used to adsorb and decolorize the No.110 wax samples with poor color,and the best decolorization process conditions were selected.Then,the material composition and physical and chemical properties of the wax-like products and adsorbents before and after decolorization were compared through a series of characterization tests such as high temperature simulation distillation,N_(2)absorption and desorption,flourier transform infrared spectrometer(FTIR),diffraction of X-rays(XRD),thermogravimetric analysis,element analysis,inductively coupled plasma atomic emission spectrometer(ICP-AES),nuclear magnetic resonance(^(13)C-NMR and^(1)H-NMR),etc.It can be found that the decolorization effect of activated clay is better than that of activated carbon,and the Saybolt color number of the No.110 wax product with high color value is+16.The reasons for the poor chromaticity of high melting point wax are not only the inorganic components mainly composed of residual ultrafine catalyst particles,but also the organic components of unsaturated carbon-carbon double bonds,heteroatomic compounds containing oxygen,nitrogen,and sulfur.The oxidative deterioration of the unsaturated carbon-carbon double bond and the broken bond of hydrocarbons with low bond energy,and the oxidation of sulfur and nitrogen heteroatom compounds may be the main reasons for the color reversion of the products after decolorization.