磷钼杂多酸钠盐脱硫制硫反应机理研究

REACTION MECHANISM OF HYDROGEN SULFIDE WITH SODIUM PHOSPHOMOLYBDATE

磷钼杂多化合物是一种新开发的面向天然气净化的液相氧化脱硫剂。笔者综合运用离子选择电极分析、差示扫描量热分析与能谱等手段对磷钼杂多酸钠盐与硫化氢的反应机理进行了研究。结果表明 ,磷钼酸钠体系在脱硫过程中具有稳定的化学性能 ,脱硫产物中基本不含 Mo、P的物相 ;磷钼酸钠吸收 H2 S过程的化学反应式为 :H2 S+Na3PMo( ) 1 2 O40 S↓ +Na3H2 PMo( ) 1 0 Mo( ) 2 O40 ,即在磷钼酸钠分子中有 2个 Mo( )被还原成 Mo( )

By using heteropoly compounds,a novel method for removing hydrogen sulfide from natural gas was developed in the previous study This method enables the simultaneous removal of hydrogen sulfide and recovery of elemental sulfur The absorbent employed has fairly good absorption regeneration performance which was competitive with the industrialized iron chelate method At present,howe ver, no proof was given on the exact number of electron transferred during the redox reaction between sodium phosphomolybdate and reductants including hydrogen sulfide With the aim to better understand the process and thus improve the process design,the mechanism of desulfurization reaction was explored with the aid of ISE(Ion selective electrode analysis), DSC(Differential scanning calorimetry) and ES(Energy spectrum analysis),and it was found that: (1)The reaction products contain little deposition compounds of molybdenum and phosphorus indicating that sodium phosphomolybdate is still much stable in its chemical property after many times of absorption regeneration cycles,and the agent loss is quite low (2)The chemical equation of sodium phosphomolybdate and H 2S was proposed to be: H 2S+Na 3PMo(Ⅵ) 12 O 40 Na 3H 2PMo(Ⅵ) 10 Mo(Ⅴ) 2O 40 +S↓ i e , there were two Mo(Ⅵ) atoms reduced to Mo(Ⅴ) Therefore, the theoretical saturation sulfur loading capacity of sodium phosphomolybdate is twice that of chelate iron with the same molar concentration