| According to the energy characteristics of our country, the important position of coal as main energy source will not change in the future for a long time, but there are many harmful substances in coal-derived synthesis gas (syngas), especially sulfur compounds (mainly as H2S and COS). These species must be removed from the syngas prior to its utilization due to their negative effects on environment, chemical processing and the health of human beings. Mid-and high-temperature desulfurization sorbent is a hot topic and key technology for the highly effective and reasonable utilization of coal resources, pollution reduction and the environment protection. Much research emphasis has been put on preparation of sorbents with a large specific surface area, high sulfur capacity, fast response, easy regeneration and stable desulfurization.In this paper, supported sorbent was synthesized with the active component ZnO, carrier modified semi-coke, additive CeO2and binder kaolin by two different way of roasting and the desulfurization tests were carried out in a homemade fixed-bed reactor. The effect of the ratio of loading, content of active component and promoter and calcination condition(temperature and time) were investigated, at the same time, the structures and properties of sorbent were characterized by X-ray diffraction, Fourier transform infrared, Transmission Electron Microscopy, Scanning Electron Microscopy, mercury poresizer, Nitrogen adsorption and X-Ray Photoelectron Spectroscopy. The main conclusions were summarized as follows:1. The specific surface area, pore volume and pore diameter were336.766m2/g,0.31cm3/g and8.063nm, respectively, which were obtained in the optimal modify process of semi-cokes. The pore size of modified semi-coke with no reunion phenomenon was concentrate on20nm, which showed more developed pore structure and looser texture.2. The active component of desulfurizer, nano zinc oxide, which prepared by solid state reaction using C2H2O4·2H2O and Zn(CH3COO)2·2H2O as raw materials. The sorbent was prepared by different method of convention and microwave heating.3. The optimal prepared conditions of convention heating are showed as follows:the ratio of loading, content of active component and promoter is10:6,30%and5%; calcinination condition is600℃and2h, respectively.4. The optimal heating conditions of microwave was500℃and1h, which was proceed in the same condition of the ratio of loading and content of active component and promoter is10:6,30%and5%, respectively5. The sorbents were characterized which were prepared using different method of microwave heating and conventional heating, XRD patterns indicated that the peak intensities derived from ZnO with complete crystal shape, sharp diffraction peak and good crystallinity disappeard, whereas those derived from ZnS appeared in the process of sulfidation. TEM results showed that the active component is circular particles about20nm, but the active component was more scattered which obtained by microwave heating. Mercury injection data showed that sorbent obtained by microwave heating has bigger specific surface area, aperture and pore size. Nitrogen adsorption and SEM results showed that the sulfidation is a padding pores process because of pore volume was declined. The XPS patterns demonstrated that binding energy of Zn2p and O1s were lower, this is because the changes of chemical environment which was caused by the effect of non-thermal, Zn2p binding energy of sulfuration sample was increased by the weakness of bonding energy of Zn-O.6. Under the optimal conditions of conventional and microwave heating, the breakthrough time is15.5h and17.5h, sulfur capacity is11.58%and13.06%, respectively. It was found that the sulfidation performance of sorbent prepared by the methods of microwave heating is higher than that sorbent prepared by conventional heating. |
PDF Full Text Request