| Nowadays, the sweetening process of light oil including liquid-liquid Merox sweetening and fixed-bed Merox sweetening is mostly used in petroleum refining industry. In liquid-liquid Merox sweetening process, two catalyst cobalt polyphthalocyanine (CoPPc) and cobalt sulfonate phthalocyanine (CoSPc) are mainly used. Due to the lower solubility of CoPPc in alkaline, its higher activity is hardly attained. CoSPc can be well dissolved in alkaline, but it converts to dioxide adduct easily in sweetening process, which reduces its activity and makes its service life shorten. CoSPc impregnated on activated charcoal bed is always used in fixed-bed sweetening process, but it is apt to run off and its cost is high. Accordingly, as catalyst of light oil sweetening,the binuclear cobalt sulfonate phthalocyanine (bi-CoSPc) was selected in this paper. Due to the double active centers in a plane, bi-CoSPc not only increases the solubility in alkaline, but also avoids its dimerisation, which expects to increase the catalyst activity in sweetening process.The synthesis method of bi-CoSPc was investigated. Disulfo-phthalic anhydride (DSPA) was synthesized by phthalic anhydride (PA) and Bi-CoSPc was prepared by DSPA, pyromellitic and dianhydride (PMDA), urea, and CoCl2. The result showed that, during the synthesis of disulfo-phthalic anhydride (DSPA), the temperature was too high to rise quickly, because of largely refluxing of SO3. The operation of separating sulfonated was complex, and large amounts of by-products were generated in the process. Furthermore, the existence of Ca2+ and NH4+ would influence the application of bi-CoSPc. During the synthesis of bi-CoSPc, the reaction system foamed seriously in final stage, which caused incomplete reaction, and reduced the yield and purity of catalyst.The sweeten efficiency of bi-CoSPc was investigated in liquid-liquid Mreox sweetening process. The suitable conditions were that the alkali concentration is 10 wt.%, the catalyst addition is 1.0 g(L-1, the reaction time is 3 min, and the reaction temperature is 40 ℃. The activities of bi-CoSPc, CoSPc and foreign catalyst (ARI 100-EXL) were compared. The results showed that, the efficiency of bi-CoSPc was better than that of CoSPc, and close to the foreign catalyst.For the problems mentioned above in preparing bi-CoSPc, the synthesis method was improved as follows: (1) In the synthesis of DSPA, the reaction temperature was lowered by adding catalyst SC, the refluxing of SO3 was avoided. The factors on the yield were researched. The suitable conditions were that, reactant ratio (SO3 : PA) is 2:1, reaction temperature is 180 ℃, reaction time is 3 h, the catalyst addition is 0.02 g·g-1. (2) Adopting Na2SO4 salting out method to separate sulfonated, not only avoided adding the Ca2+ the NH4+, but also increased the yield of DSPA. The suitable concentration of Na2SO4 is 0.15 g·mL-1 for higher yield and purity of DSPA. (3) In the synthesis of bi-CoSPc, adding NaOH solution to reaction system in final stage, not only eliminated the influence of NH4+, but also weakened foaming. So the yield and purity of catalyst could be increased. The suitable conditions were attained: reactant ratio (DSPA:PMDA) is 6:1, reaction temperature is 220 ℃, reaction time is 1 h.In order to investigate the activity of bi-CoSPc to the higher thiol oxide, the 1-octanethiol oxidation rate was determined, the result showed that, the rate of 1-octanethiol oxidation increased with rising of reaction temperature, concentration of catalyst, and concentration of alkali. At the same condition, the activity of bi-CoSPc was higher than CoSPc. The kinetics of 1-octanethiol catalytic oxidative reaction was preliminarily researched based on the experimental results. The rate of reaction could be described by the equation: , the reaction order of 1-octanethiol is 1.07, and activation energy is 23.913 KJ·mol-1.
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