Study On The Removal Of Qxygen Compounds From Fischer-tropsch Synthetic Oil

Fischer-tropsch synthetic oil contains not only a large number of linear alpha-olefin and alkanes,but also some organic oxygen-containing compounds.The removal of oxygen-containing compounds is an essential step in the production of α-olefin from Fischer-Tropsch synthetic oil.In this paper,the removal of oxygen-containing compounds from Fischer-Tropsch synthetic oil was studied by liquid-liquid extraction and adsorption with C8 fraction as raw material.Ester extractants were selected by single stage extraction experiment using simulated C8 as raw material.The extraction conditions were optimized using simulated components and real Fischer Tropsch synthetic oil C8 fractions.When the ratio of agent to oil was 3.5,the temperature was25 ℃-50 ℃,and the carbonyl concentration of raw material was greater than1000 μg/m L,the alcohol removal rate of simulated material was greater than96%.The carbonyl removal rate of the two materials is greater than 83%.Under the same conditions,the oxy-containing compounds in C6,C7 and C9 fractions of Fischer-Tropsch oil were removed.The removal rates of carbonyl group were 91%,86% and 81%,respectively,and the removal rates decreased with the increase of carbon number.On this basis,the extraction process of Fischer-Tropsch synthetic oil C8 fraction was investigated by using Reciprocating Sieve Plate Extraction Column(RPC).The optimal operating conditions were obtained as follows:vibration frequency of 55 times /min,sieve plate opening rate of 45%,sieve plate number of 18 plates,and carbonyl group removal rate of 94%.Subsequently,the technological conditions of the Centrifugal extractor were investigated.The optimal operating conditions were obtained as follows: the drum speed was 5500 r/min,the extraction-stage was 1.and the carbonyl removal rate was 83% under the technological conditions.With the purity and yield of the extractant as the ultimate goal,the extraction recovery process conditions were explored.Under the conditions that the raw material feeding position was the upper part of the distillation column,the feed flow rate was 5.8 m L/min,the temperature of the tower was232 ℃,and the reflux ratio was 2,the extraction purity and recovery rate could be up to 99%.The C8 fraction was further refined by adsorption after the removal of oxygen compound.Firstly,X-type molecular sieve was selected as the adsorbent for removing the remaining oxygen-containing compounds in oil products.Dynamic adsorption experiment was used to optimize the adsorption conditions of X-type molecular sieve.The experiment showed that no oxygen-containing compounds were detected before adsorption penetration,and the carbonyl concentration of oil in the effluent was less than 10 μg/m L.In the dynamic adsorption experiment,the back pressure valve pressure,flow rate and the flow state in the adsorption column will affect the penetration curve of X-type molecular sieve.In the dynamic adsorption experiment,when the back pressure valve pressure is 0.2 Mpa,the adsorption capacity of adsorbent is 8.65 mg/g.When the flow rate of raw oil was 1 m L/min,the adsorption capacity of adsorbent was 8.65 mg/g.When Reynolds number of adsorption column is 20.3,the adsorption capacity is 9.22 mg/g.Under the same conditions,oxygen compounds in C6,C7 and C9 fractions were adsorbed and refined.The adsorption capacity of adsorbent decreased from37.80 mg/g to 6.45 mg/g with the increase of carbon number.