Catalytic Active Species And Purification Process Investigation For Preparation Of Sodium Sulfide By Hydrogen Reduction Of Anhydrous Sodium Sulfate

Sodium sulfide is a strong base compound with strong reducibility,which has important applications in the fields of dyes,textile industry and chemical products and so on.At present,the preparation method of industrial sodium sulfide mostly adopts the method of coal powder reduction technology,which has complicated operation processes,creates large energy consumption and brings serious pollution problems.The research on the production technology of sodium sulfide via the reduction of anhydrous sodium sulfate by gas reduction method has been gradually emerging in recent years.The operation is simple and the yield of sodium sulfide is high.However,the active components in the catalytic system used in this method are rarely researched,and there have been few reports and studies on the methods for separating and purifying sodium sulfide with impurities.Therefore,this thesis used gas reduction method to prepare sodium sulfide under high temperatures as well as explored the optimal reaction time,the main catalytic active species and the methods of separation and purification.The research contents and results are as follows:?1?Sodium sulfide was prepared using H₂ reduction on?-Fe₂O₃ catalyst.The catalytic performance of the catalyst in different reaction time and the optimum reaction time was explored.The results showed that the optimum reaction time was4 hours and the content of Na₂S in the crude product reached 90%.?2?The synthesized nano-Fe and nano-Fe₃O₄ catalysts were respectively used to prepare sodium sulfide at different reaction time.The yield of sodium sulfide was tested and the active components in the reaction were explored.The results showed the non-valent iron is the dominant active component and the content of main product Na₂S was above 98%.?3?The crude product of sodium sulfide was separated and purified by adding alkaline metal oxide and hydroxide of different quality,and two purified products of Na₂S·5H₂O and Na₂S were obtained,respectively.The content of hydrated sodium sulfide of one of the purified products is over 95%,and the content of impurity Na₂SO₃,Na₂S₂O₃ and Fe is very low,which can meet the requirments of the national standard GB10500-2009?Na₂SO₃?1.0%,Na₂S₂O₃?2.5%?.The content of Na₂S in another purification product was up to 66.9%,and the impurity content was not up to the ntional standard except Fe.