4种窄馏分费托蜡组成结构与性质

Composition structure and properties of four narrow fraction Fisher-Tropsch waxes

以国家能源集团宁夏煤业间接液化示范装置生产的费托合成粗蜡为原料,通过溶剂萃取耦合分级结晶工艺分离出4种窄馏分蜡,分别采用气相色谱法(GC)、傅里叶红外光谱法(FT-IR)、差示扫描量热法(DSC)和热重分析法(TG)等表征手段对4种窄馏分蜡的组成、结构和性质进行了分析。结果表明:4种窄馏分蜡组成相似,碳数呈正态分布,且以长链烷烃为主。随着窄馏分费托蜡分子量的增大,其熔点、结晶热、烷烃支化度和热稳定性均呈递增趋势。由此可见,溶剂萃取耦合分级结晶工艺可以按照需求得到熔点不同的精制蜡产品,对低附加值的粗蜡进行较好的精细分离。

The Fischer-Tropsch synthesis crude waxes, which were produced by indirect coal liquefaction demonstration units from China Energy Ningxia Coal, were separated into four narrow fraction waxes by solvent extraction coupled with fractional crystallization. The composition, structure and properties of the four narrow fraction waxes were investigated by Gas Chromatography(GC),Fourier Transform Infrared Spectroscopy(FT-IR),Differential Scanning Calorimetry(DSC),Thermogravimetric Analysis(TG) and other characterization methods. The results show that the four narrow fraction waxes are similar to each other in composition, with a normal distribution of carbon numbers and mainly composed of long-chain alkanes. With the increase of molecular weight of the narrow fraction waxes, their melting point, crystallization enthalpy, degree of branching of alkane and thermal stability all show an increasing trend. It can be concluded that solvent extraction coupled with fractional crystallization can obtain refined waxes products with different melting points according to requirements so that the crude waxes with low added value can be better separated.