Sorbents For Hot-gas Desulfurization Prepared By Ultrasound-assisted Impregnation And Sol-gel Method

Hot-gas desulfurization sorbents were prepared by three methods respectively, including ultrasound-assisted impregnation method, classical impregnation method and sol-gel method. The physical and chemical properties of sorbents were analyzed by means of ICP-AES, SEM, and XRD. The desulfurization activities of high temperature desulfurization sorbents were studied in a fixed-bed reactor. The results are as follows.(1) Six hot-gas desulfurization metal sorbents including Fe, Mn, Cu, Ce, Ca and Zn were prepared by an ultrasound-assisted impregnation method and by a classical impregnation method. ICP results showed that the use of ultrasond increased the content of active ingredient in the sorbents, improved the pore structure, and thinned the particles. SEM results revealed that the sorbents was small in granule, uniform grading and less sintering with ultrasonic treatment. XRD results showed that the use of ultrasond had an affect on the dispersion of crystal grain. The activity test results indicated that the desulfurization activity of the sorbents prepared by ultrasound impregnation was much higher than those without ultrasonic treatment, especially for the Fe sorbent. The desulfurization activity order of the six metal sorbents is Fe>Mn>Cu>Ce>Ca>Zn.(2) Three hot-gas desulfurization metal sorbents including Mn/SiO2, Mn/TiO2, and Mn/γ-Al2O3, were prepared by ultrasound-assisted impregnation method for the purpose of studying the effect of the carrier. The carrier study showed that, Mn/γ-Al2O3 got higher BET surface area and better performance, was fit for IGCC hot-gas desulfurization. But Mn/SiO2 cannot keep the H2S concentration at a low level in a long time, and Mn/TiO2 was bad in high temperature stability.(3) Mn desulfurization sorbents were prepared by an ultrasound-assisted impregnation method and a sol-gel method with the same load. The sol-gel method got higher BET surface area, better performance and activity. XRD results showed that Mn active ingredient was in uniform distribution, which is good for the desulfurization reaction. The activities of the sorbents increased with the increasing of the temperature. In short, sol-gel method gets better performance, but in high price and with difficult preparation. It is still difficult to get a widely industry application now.