Desulfurization And Regeneration Kinetics Of Zinc Ferrite High Temperature Coal Gas Desulfurizer

China is rich in coal resources, meanwhile coal production and consumption rank first in the world. It is important to use the coal resource efficiently and transformed cleanly for our country’s social and economic sustainable development and environmental protection. Due to the advantages of high thermal efficiency and low pollution, IGCC, CBPG, IGFC etc. was considered to be the most promising coal energy conversion and utilization technologies in 21 st century. But in the raw coal gas, H2 S not only corrode the production equipment but also cause catalyst poisoning. Comparing with wet desulfurization, dry desulfurization has great significance for its low heat loss, high desulfurization precision and low operating cost etc. Currently, the composite metal oxides of zinc ferrite is one of the most widely used in high-temperature gas desulfurizing field.In this paper, with C₄H₆O₄Zn·2H₂O, Fe（NO₃）₃·9H₂O and H₂C₂O₄·2H₂O as raw material and the red earth as binder, the precursor of zinc ferrite was synthesized by solid-state method. Two types of zinc ferrite sorbents was prepared through different heating methods—microwave and muffle furnace. Through contrast experiments as well as a series of characteristics（XRD, SEM, XPS, EDS and BET etc.）, two preparation methods was studied the impact on the microstructure and desulfurization performance of sorbents. The sulfurization kinetics of sorbents were studied through the fixed bed reactor. The regeneration kinetic of the desulfurizer prepared by microwave calcination was researched in O2 atmosphere using thermal differential analyser. The main conclusions are as follows:1.Through the desulfurization performance test of sorbents prepared by two kinds of methods of convention and microwave calcination, we can find that: the sulfur capacity of sorbent prepared by convention calcination is 7.16%; the mechanical strength is 32.8 N/cm; the sulfur capacity of sorbent prepared by microwave calcination is 8.61%; the mechanical strength is 41.7 N/cm; Under the same experimental conditions, the sulfur capacity and mechanical strength of desulfurizer prepared by microwave calcination are superior to the sorbent prepared by convention calcination.2.The desulfurizers prepared by two methods sintered by different method was characterized by XRD, XRD, SEM, EDS, XPS and BET. The conclusions of these analyses are as follows: The XRD spectra shows the desulfurizer prepared by microwave calcination has better crystalline state, lager grain size and more uniform dispersion indicates that the microwave calcination is better for reaction. Comparing with the sorbent prepared by convention calcination, the photographs of SEM shows that active component dispersed evenly, and the particle size of samples were uniform, and some pores were existed in the sorbent prepared by microwave calcination. In the pictures of XPS spectra, the binding energy of Fe2 p, Zn2 p and O1 s of sorbent prepared by microwave calcination were lower than the other sorbent, and more easier occurring reaction for the H2 S. The elements’ content of Zn, Fe and O on surface of sorbent prepared by microwave calcination were higher is corresponding to the result of EDS analysis that microwave calcination could accelerate the migration of metal elements, and could promote the chemical reaction on surface of sorbent which is same as the conclusion of sulfurization kinetics. The analysis of BET shows that two kinds of desulfurizers both had the typical IV isothermal adsorption and desorption curve, and the most holes were mesoporous with the hysteresis loop of H3, meanwhile the specific surface area, the pore volume and pore diameter of the sorbent made under microwave condition were bigger than conventional calcination condition.3.The sulfurization kinetics experiments of two kinds of sorbents were tested in the fixed bed reactor. The experimental results show that: the chemical reaction activation energy and corresponding frequency factor of the desulfurizer prepared by convention are 4.581 kJ/mol and 0.419 m/min, respectively; While the diffusion activation energy and corresponding frequency factor are 35.757 kJ/mol and 2.558×10-4 m2/min, respectively; the chemical reaction activation energy and corresponding frequency factor of the desulfurizer prepared by microwave calcination are 4.079 kJ/mol and 0.396 m/min respectively; While the diffusion activation energy and corresponding frequency factor are 30.732 kJ/mol and 2.528×10-4 m2/min respectively.4.The regeneration kinetics experiments of the sorbents in O₂ atmosphere were tested in the thermogravimetric analyzer. The experimental results show that: the chemical reaction activation energy and corresponding frequency factor are 16.08 kJ/mol and 1.08 m/min respectively. While the diffusion activation energy and corresponding frequency factor are 37.22 kJ/mol and 4.08×10-4 m2/min respectively.