Preparation Of Copper-Zinc Adsorbent And Its Desulfurization Mechanism For Thiophene In Coke Oven Gas

Coke oven gas,being rich in hydrogen,is a high-quality raw material for synthesis gas.In the process of coke oven gas utilization,the thiophene sulfur in it can cause the permanent poisoning of the catalyst.In order to meet industrial requirements,the thiophene sulfur concentration needs to be reduced to ppbv level.Catalytic hydrogenation is the most widely used method to remove thiophene,but it is difficult to achieve super deep removal of thiophene sulfur using this method,and the experimental conditions are harsh.The reactive adsorption desulfurization(RADS)method is a desulfurization method that combines hydrogenation and adsorption,which has the advantages of mild reaction conditions and high desulfurization accuracy for thiophene sulfur-containing compounds.Studies have shown that Cu O-Zn O adsorbent successfully reduces the concentration of thiophene sulfur in coke oven gas to ppbv level through reactive adsorption desulfurization.On the basis of achieving the accuracy requirements,the preparation of adsorbent with high sulfur capacity is the core of clean and efficient utilization of coke oven gas.The sulfur capacity of adsorbent can be effectively improved by optimizing the preparation conditions of adsorbent.At the same time,the research on the mechanism of Cu-based adsorbent RADS is to improve the theoretical basis and direction for the preparation of high-efficiency adsorbent.Therefore,the orthogonal experimental method and the single factor variable method were used to optimize the preparation conditions of the adsorbent,and the mechanism of the RADS of the Cu-based adsorbent is discussed in this paper.The main conclusions are as follows:(1)Optimizing the preparation conditions of C-Z adsorbent through orthogonal experiments,the best preparation conditions are reaction temperature60 ?,calcination temperature 350 ?,Cu/Zn atomic ratio 1.00,solution concentration 0.3 mol/L.The breakthrough adsorption capacity for thiophene of the adsorbent obtained under this condition is 20.87 mg/g.On this basis,the preparation conditions of the adsorbent were screened in depth through a single factor experiment.The optimal preparation conditions are p H value 7.5,Cu/Zn=1.00,calcination temperature 300 ?,the breakthrough adsorption capacity for thiophene of the adsorbent obtained under this condition is 25.08 mg/g.(2)Summarizing the optimization conclusions of the two conditions,it is found that the calcination temperature has the greatest influence on the adsorption desulfurization performance.It mainly affects the specific surface area,pore volume,dispersibility and particle size of the adsorbent.The calcination temperature is in the range of 300 ?-550 ?.As the temperature increases,the adsorbent will agglomerate,resulting in the damage of active components and the decline of desulfurization performance.(3)Researching on the mechanism of Cu-based adsorbent RADS,it is found that C-Z₀ adsorbent can adsorb thiophene and make it ring-open,and the Cu S product has formed while C-Z?adsorbent does not have the ability to react with thiophene,indicating that Cu is the active center of thiophene ring-opening and has the ability to adsorb S.The presence of Zn S was found in the spent C-Z adsorbent,indicating that Cu first reacted with thiophene to produce CuS,and then S reacted with ZnO to produce ZnS.