双核磺化酞菁钴与硫化钠反应的伏安法研究

Voltammetry study on the reaction between binuclear sulfonated phthalocyanine cobalt and sodium sulfide

PDS脱硫法有效解决了氰化氢中毒问题,得到许多企业的青睐,但副盐问题仍然是目前整个脱硫行业十分关注的话题。采用循环伏安法对PDS脱硫体系中双核磺化酞菁钴(bi-CoPc)与硫化钠的反应过程进行了研究。结果表明:Na2S和Na2Sx在玻碳电极上的氧化反应是受浓度扩散控制的不可逆反应,且S^2-向S8 的转化并不是一步完成,而是先转化成Sx^2-,进而再生成S8。此外,参与反应的S^2-仅有20%转化为S8。Sx^2-以S2^2-~S9^2-中的某两种形式为主要存在形式,且Sx^2-的存在形式可能对于S8 的生成速率和生成量有一定影响。bi-CoPc在水溶液中易与 OH^-形成配合物,加入碳酸盐缓冲溶液,可降低配合物的形成能力,同时,Co^+/Co^2+的氧化还原反应更易发生。bi-CoPc与 Na2S反应先生成S2^2-,然后S2^2-可转化为更长链的Sx^2-,最终形成S8。该研究结果有助于加深对脱硫机理的了解,同时,对降低副产物生成有一定的指导意义。

PDS desulfurization method has been applied widely because of effectively solving the problem of hydrogen cyanide poisoning.However,the by-products problem is still a hotspot concerned in whole desulfurization field at present.The reaction between binuclear sulfonated phthalocyanine cobalt (bi-CoPc) and sodium sulfide was studied by the cyclic voltammetry in this paper.The results showed that the oxidation reaction of Na 2S and Na 2S x on glassy carbon electrode was an irreversible process controlled by concentration diffusion.And the transformation from S^2- to S 8 was not a one-step process,but firstly transformed into the intermediate,S^2- x ,then further generated S 8.Moreover,it was deduced that only 20% of S^2- involved in the reaction was converted into S 8.S^2- x had two main existing forms within the range from S2^2- to S^2- 9,and their forms might have influences on the formation rate and production amount of S 8.Bi-CoPc could be more readily form the coordination complex with OH^- in aqueous solution than in carbonate buffer system,but the redox reaction of Co^+/Co^2+ is easier in carbonate buffer system than in aqueous system.Meanwhile,S2^2- was formed firstly in the reaction between bi-CoPc and Na 2S,S2^2-then could transformed into S^2- x with a longer chain,finally formed S 8.It was helpful for us to understand the mechanism of PDS desulfurization,and it also had guiding significance for reducing the formation of by-products.