Preparation of supported polystyrene sulfonate catalyst modified by surfactant
The modification of silica gel carrier by surfactant can avoid the agglomeration of polystyrene on the surface of the carrier,and then the supported organic sulfonate solid acid catalyst was obtained by sulfonation.The obtained catalyst was characterized by specific surface area detection(BET),thermogravimetric analysis(TG),NH3 temperature programmed de-sorption(NH3-TPD),scanning electron microscopy(SEM)and elemental analysis.The preparation conditions of the cata-lyst were optimized and the performance in the synthesis of tributyl citrate was investigated.The deactivation mechanism of the catalyst was discussed as well.The results show that the polystyrene molecules are effectively dispersed on the surface of silica gel under the action of cetyltrimethylammonium chloride(CTAC),which is beneficial to the sulfonation process and the number of sulfonic acid groups increases.Under the optimum reaction conditions,the yield of tributyl citrate can reach 88.1%.The catalytic activity did not decrease significantly after six consecutive cycles,exhibiting good stability.The pre-pared catalyst has the same deactivation reason with the resin catalyst,which is caused by the loss of sulfonic acid group a-lone,and the loss of sulfonic acid groups in the prepared catalyst is much lower than that in the resin catalyst.
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