Researches On Zn-Mn-Cu Sorbent Loaded On Semi-coke Prepared By Ultrasound-assisted High-pressure Impregnation Method And Its Desulfurization And Regeneration

Coal gasification is the main approach and leading technology of cleancoal utilization. In the process of coal gasification, sulfur-containing pollutantswill be inevitably produced and more than90%of the sulfur pollutants is in theform of H2S. The release of H2S in gasification will bring serious disadvantages.The high content of H2S in syngas can corrode equipment and pipes in hot andhumid conditions, poison the catalyst in the application of coal-based gas. In thecoal-based gas purification process, metal oxide sorbents are generally used toremove sulfur-containing gases at mid-temperature for avoiding the heat lossand the problem of―hot and cold changing‖in the conventional desulfurizationprocess. The preparation of sorbent and its desulfurization performance are themain concerns.Based on the previous research of our lab, ultrasonic treatment wasintroduced into the preparation process of desulfurization sorbent byhigh-pressure impregnation method in this study. Semi-coke, as an inexpensive support, was selected to prepare Zn-Mn-Cu sorbent by ultrasound-assistedhigh-pressure impregnation method. A series of sorbents were prepared andtheir desulfurization performance was tested in a fixed bed reactor at500oC. Inorder to analyze the impact of preparation process on the desulfurizationcapacity of sorbents and the dispersibility of active component on semi-coke,physical and chemical properties of sorbents were also investigated by XRD,BET and TEM.The main conclusions are as follows:a. The sorbents prepared by ultrasound-assisted high-pressureimpregnation method had a better desulfurization performance than sorbentssynthesized by conventional high-pressure impregnation, in which H2S in coalgas could be removed from1000ppm to0.1ppm at500oC, with the sulfurcapacity and breakthrough time increasing by31.6%and51.5%,respectively.The increase of the specific surface area and improvement of the pore structurewere more remarkable for the sorbent prepared by ultrasound-assistedhigh-pressure impregnation method.b. The optimum preparation conditions of ultrasound-assistedhigh-pressure impregnation method were that impregnation temperature was200oC, ultrasonic power was120W, ultrasonic time was90min and calcinationtime was2h. The best sorbent could remove the content of H2S in the feed gas(N2+H2S) from2000ppm to0.2ppm, holding for21.5h with the sulfurcapacity of16.7%. c. The effects of temperature、 oxygen content and oxygen-steamregeneration atmosphere on the sintering of the sorbent porous structure, thepulverization and the ignition loss phenomenon of support had beeninvestigated. The study has revealed that element C and S have a competitivereaction with O2in the regeneration process of carbon materials baseddesulfurizers.