| At present time, China is in the key period of modernization, industrialization and urbanization, while energy is the important foundation of the national economy and social development, so there is an urgent need to establish a clean and reliable energy supply system. Coal gasification technology has been widely concerned as a modern clean coal utilization technology. And gas purification technology is one of the key technologies of coal gasification. The development of gas desulfurization sorbents over a period of time has changed from mono metal oxide into composite metal oxides. Nanometer zinc ferrite as a new type of inorganic functional material with spinel structure, have been received extensive focus as the gas desulfurization sorbents, because of high sulfur capacity and desulfurization accuracy.In this paper, using ferric chloride, zinc chloride and sodium hydroxide as raw materials, the precursors of nanometer zinc ferrite were prepared by low temperature solid state reaction. While the preparation of nanometer zinc ferrite was assisted by muffle furnace roasting. The influences that act on zinc ferrite grain size of the calcination time and calcination temperature have been investigated, as well as the grain growth kinetics of zinc ferrite. The desulfurization sorbents were prepared use one-step calcination through microwave muffle furnace and conventional muffle furnace, respectively. Then the performance of the two calcination methods for removing hydrogen sulfide were inspected through the simulation Texaco coal gas in fixed bed reactor. The samples were characterized by Nitrogen adsorption instrument (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Thermo-gravimetric (TG-DSC) and Fourier infrared spectrometer (FT-IR). And the properties that were characterized will be associated with the vulcanization behaviors to get relationship between the vulcanization behaviors and methods that conduct the sorbents, as well as to optimize the performance of desulfurizer. The main conclusions are as follows:(1) The semi-cokes were treated by HNO3and HF to deashing before the semi-cokes activated by N2and H2O at high temperature, while the physical and chemical activation are the usual methods. The semi-cokes thought to get a much better performance at700℃last for2h after the investigation of activation time and temperature. With the increase of activation time and temperature, the surface area and pore volume have a trend that increase before it is get down. The specific surface and the mean pore size are239.5m2/g and5.18nm, respectively.(2) The precursors were obtained by ferric chloride, zinc chloride and sodium hydroxide as raw materials through solid state synthesis method which the optimal molar ratio is2:1:10. At about400℃, iron oxide and zinc oxide which two come from the partially decomposition of precursor react into the zinc ferrite with a spinel structure. The grain size of zinc ferrite increased with the calcination temperature and time increasing.(3)As to the nanometer zinc ferrite, the phenomenological theory of the grain growth kinetics was used to calculation the grain growth kinetics at400℃～700℃,which shows that the average grain growth index of ZnFe2O4prepared by microwave heating and conventional calcinations are9.6and10.6, respectively. Their average grain growth activation energies are122.1kJ/mol and179.4kJ/mol.(4)At the temperature of600℃, roasting time is2h, while the load ratio and active component content are10:8and25%, respectively. The zinc ferrite loaded on semi-coke through one-step conventional calcination method gets the longest breakthrough time. The mechanical strength of desulfurizer touches the line of standard without a phenomenon of pulverization. While the sulfur capacity reach a maximum of8.58(g S/100g sorbents).(5)The zinc ferrite desulfurizer supported by semi-cokes was prepared by the method of one-step with microwave irradiation. The breakthrough time reached10h with the active component is unchanged at25%, while the load ratio of10:6and microwave irradiation lasts for2h at500℃could be considered as the optimum preparation conditions.(6)The sulfur capacity of desulfurizer that prepared by microwave method last for2h at500℃is9.16, which is significantly much more than that of the conventional method at7.29(g S/100g sorbents). And the desulfurization efficiency is91.6%and72.9%respectively. When the calcination temperature at600℃last for2h, desulfurizers were prepared by microwave and the conventional methods have a sulfur capacity of7.49(g S/100g sorbents) and8.58(g S/100g sorbents), the desulfurization efficiency is74.9%and85.8%, respectively. |
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