低熔点费托蜡的组成、结构及性质

Composition,structure and properties of low melting Fischer-Tropsch waxes

采用气相色谱法(GC)、X射线衍射法(XRD)和差示扫描量热法(DSC)等手段研究了52号费托蜡与4种典型的石油基52号石蜡的组成、结构及性质。结果表明:5种蜡均以长链烷烃为主,费托蜡的碳数分布比较集中,正构烷烃含量、色度值高于石油基蜡,异构烷烃的含量、针入度及含油量均低于石油基蜡。常温下,费托蜡和石油基蜡均为正交晶体。费托蜡具有与石油基蜡相近的热性质,均存在一个较弱的固-固相转变峰和较强的固-液相转变峰。由偏光显微镜的结果可知费托蜡蜡晶为斜方形片状晶体,排列紧密。在降温过程中,片状蜡晶的径向尺寸逐渐增大,蜡晶会不断聚结形成大的固体晶团,进而形成三维空间网络结构。表明52号费托蜡正构烷烃含量较高,与气相色谱结果一致。由此可见,52号费托蜡在物理性质与化学组成上优于石油基蜡,在晶体结构与热性能方面与石油基蜡相似,可作为石油基蜡的有效补充。NICE研发的低毒特种萃取剂能够实现在无芳烃体系中生产符合国标的48~54号全精炼蜡,有望替代传统溶剂。

The composition,structure and properties of No.52 F-T wax and four kinds of No.52 petroleum wax were investigated by the use of Gas Chromatography(GC),X-ray diffraction(XRD),Differential Scanning Calorimetry(DSC)and other characterization methods.The results show that the five waxes are mainly composed of long-chain alkanes,and in compared with petroleum waxes,the F-T wax has narrow carbon number distribution,highn-alkane component content,high saybolt color value,low iso-alkane component content,low needle penetrationvalue,and low oil content.At room temperature,both F-T and the petroleumwaxeshave the orthorhombic crystal structure.F-T wax has similar DSC as petroleum wax with respect to a weak solid-solid phase transition peak and a strong solid-liquid phase transition peak.According to the results of the polarized microscope,the oblique square sheet-shaped crystals are arranged closely.In the process of cooling,the radial size of the sheet wax crystal gradually increases,and the wax crystal will continue to form a large solid crystal group,thus forming a three-dimensional spatial network structure.It indicates the high content of n-alkanes in the wax of No.52,which is consistent with the GC results.The No.52 F-T wax is better than petroleum wax in terms of physical pr-operties and chemical composition,and is similar to petroleum wax with respect to crystal structure and thermal properties.The No.52 F-T wax can be used as petroleum wax.The low-toxicity special extraction agent developed by NICE can realize the production of No.48-54 fully refined paraffin wax in the aromatics-free system,which is expected to replace the traditional solvent.