Purification And Catalytic Mechanism Of Sodium Sulfide Crude Product Prepared By Hydrogen Reduction

Sodium sulfide,as a strong reducing and strong basic inorganic compounds,has important application in many fields.At present,the sodium sulfide industrial product was produced mostly using pulverized coal reducing method,facing big environmental load and high impurity content issues,limiting the high value-added products of sodium sulfide for further development and utilization.In particular,sodium sulfide as the raw materials of the new PPS resin which is a rise in recent years,must meet the requirement of high product purity.Therefore,the development of new technology to prepare high purity sodium sulfide is of great significance.One-step gas reduction method has made great progress because of its simple process and high purity sodium sulfide product.The technics and catalyst for this reaction have been studied for many years in our laboratory.However,due to the special physicochemical properties of sodium sulfide,the purification of crude products and separation of the catalyst are still challenge issues.In this thesis,firstly,two different a-Fe2O3 catalysts were prepared by solid phase method,and their catalytic performance for hydrogen reduction sodium sulphate in fluidized bed was studied.The recycling and catalytic mechanism of the catalyst extracted from the crude product was also explored preliminarily.Secondly,the crude product of sodium sulfide was purified using water and ethanol as solvents in order to find an efficient purification method.Finally,the experimental conditions for purification of the crude sodium sulfide product by ethanol purification were orthogonally optimized,and the optimum experimental conditions were established.The results show that the catalytic mechanism might be the cocatalyzed effects of the mixed iron oxides,and catalytic performance of G-900-1 a-Fe2O3 catalyst is the best;the content of Na2S in the crude product can be up to 95.2%.The purification efficiency for the crude sodium sulfide with anhydrous ethanol as solvent under vacuum distillation was much better than that with water as solvent.The purified product by ethanol purification method is Na2S·5H20 with the content of 98.3%,and the sum of Na2SO3 and Na2S2O3 is 1.4%,Fe content is 0.0023%.All specifications meet the national standards.This work bascically solved the catalyst separation and product purification issues,and the obtained product could meet the requirements for production of polyphenylene sulfide.