超临界和近临界条件下Fischer-Tropsch合成研究:溶剂的影响(英文)

Supercritical and near-critical Fischer-Tropsch synthesis: Effects of solvents

研究了超临界和近临界条件下费托合成过程中溶剂对反应行为的影响。反应在固定床反应器中进行，催化剂为Co／SiO2，所选择的溶剂有两类：纯溶剂（正戊烷和正己烷）和混和溶剂（由正己烷和少量的C5-10烃组成）。结果表明，正己烷分压对CO转化率影响很小，但是产物中1-烯烃含量随正己烷分压增加而增加，超临界条件下1-烯烃含量明显高于非临界条件下。溶剂的种类对CO转化率、CH4和CO2选择性以及产物炭分布影响不大。这一结果表明为了减少溶剂用量，对含有适量轻组分（C5-10）的正己烷溶剂进行循环使用是可行的。结果同时表明与正己烷相比，混和溶剂（25％正己烷和75％正葵烷）具有较高的1-烯烃选择性。

The effect of solvents on the reaction performance of Fischer-Tropsch synthesis under supercritcal and nearcritical conditions was studied in a fixed bed reactor. Two kinds of solvents： pure solvents （ n-hexane and n-pentane） and mixed solvents （ the solvent consists mostly of n-hexane and some content of C5 to C10 normal paraffins and normal olefins） were chosen as the solvent. The catalyst used was a SiO2 supported cobalt catalyst. The results showed that the partial pressure of n-hexane had little influence on the CO conversion when total pressure and syngas partial pressure were kept constant. 1-olefins content in the products, however, increased with increasing partial pressures of n-hexane. 1-olefins content in the products under supercritical condition was obviously higher than that under non-supercritical conditions. Similar CO conversion, CH4 and CO2 selectivities and hydrocarbon distribution were obtained in different pure media： n-pentane and n-hexane. 1-olefins content in n-pentane was slightly lower than that in n-hexane. Compared with pure n-hexane solvent, the solvent with mainly n-hexane and some C5 - 10 components had similar effects on CO conversion, CH4 and CO2 selectivities, and hydrocarbon selectivity of the products. This result suggested that the recycle of the supercritcal solvent contained some content of lighter fractions （ such as C5 - 10 ） produced in the FT process is possible for reducing the amount of supercritical solvent during supercritical FT process. The binary mixed solvent （ 25 % n-hexane/ 75% n-decane） showed much higher 1-olefins selectivity than the pure n-hexane probably because of its higher solubility to heavier products.