热煤气一体化净化工艺中的脱硫反应特征

利用固定床反应器考察了高温煤气脱硫除尘一体化净化工艺中沉积粉尘对高温煤气脱硫剂脱硫性能的影响.结果表明,表面沉积粉尘对脱硫剂初次硫化行为有明显的影响,且与脱硫剂的组成和结构有关.利用钢厂赤泥制备的脱硫剂,含有多种惰性杂质,且具有较大的孔径结构,易于和粗煤气中的粉尘作用,造成脱硫剂硫容的减小.硫化气氛中,H2O的存在造成脱硫剂硫容和脱硫效率的降低,但不会影响因表面沉积粉尘造成的脱硫剂硫容的减小.多次硫化-再生循环实验表明,硫化-再生循环过程有助于减小表面沉积粉尘对脱硫剂脱硫行为的影响.经历一定次数的硫化-再生循环后,粉尘对脱硫剂脱硫行为的影响逐渐消失.     

复合金属氧化物脱除羰基硫的研究

采用共沉淀法制备铁锰复合金属氧化物脱硫剂,从温度、空速和羰基硫浓度几个方面考察对脱硫剂脱硫性能的影响.实验结果表明,该脱硫剂在250℃～350℃,强还原性气氛下,具有较高的有机硫脱硫精度和较大硫容.实验还考察了氧化锌、氧化铜、氧化镍和氧化铈几种添加剂对脱硫剂脱硫效果影响,结果表明,脱硫剂中添加氧化镍和氧化铈后脱硫精度有较大提高,出口羰基硫浓度低于0.1×10-6,添加氧化铜和氧化锌的脱硫精度为0.2×10-6;此外,添加氧化锌脱硫剂硫容较大,穿透硫容为25%,而添加氧化铈的脱硫剂硫容相对较小.     

高温煤气脱硫剂的开发研究

本文对高温煤气脱硫剂的制备及脱硫工艺条件做了研究，并对脱硫剂进行了十五个周期的脱硫再生循环试验。结果表明,制备的脱硫剂在600～620℃、常压及空速为1000h-1的条件下脱硫，脱硫剂强度及硫容没有出现明显下降，也没有出现脱硫剂的粉化现象。     

三维有序大孔Fe_2O_3/SiO_2复合脱硫剂中温脱硫性能及再生行为研究

采用胶晶模板法制备了一系列具有三维有序大孔结构的氧化铁和氧化铁-二氧化硅复合脱硫剂,并采用固定床动态实验考察了其中温脱硫性能及其再生行为。硫化前后样品采用X射线衍射仪(XRD)、N_2吸附、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术进行了表征。结果表明,与三维有序大孔氧化铁脱硫剂相比,脱硫剂中引入SiO_2可以极大地提高脱硫剂的比表面积和Fe_2O_3的分散性,并且可以减小Fe_2O_3的晶粒尺寸,进而有利于提高脱硫剂的脱硫精度和脱硫性能。另外,脱硫剂的脱硫性能与PS微球的直径和硫化温度有关,样品的脱硫性能随着PS微球直径的增大和硫化温度的升高均呈现先增大后减小的趋势。当PS微球直径为175 nm,脱硫温度为300℃时,脱硫剂的硫容最优,其穿透硫容和饱和硫容分别为51.6%和73.2%。再生实验结果表明,三维有序大孔结构可以极大地降低样品的再生温度,样品的最佳再生温度为300℃。     

硫化条件对氧化铈高温煤气脱硫剂的影响

氧化铈是一种新型的高温煤气脱硫剂,它的主要优点是再生过程中能产生单质硫。本文采用工业硝酸铈Ce（NO3）3.6H2O为原料制取CeO2,用干混法制备CeO2高温煤气脱硫剂。在固定床反应器中考察不同空速、不同硫化温度以及水气氛对脱硫剂脱硫效率的影响。结果表明：硫化温度800℃,空速1 500 h-1脱硫剂的脱硫效率较高;水气氛的存在,抑制了脱硫剂的还原与硫化,使得脱硫剂的脱硫效率下降。     

三维有序大孔Fe_2O_3/SiO_2复合脱硫剂中温脱硫性能及再生行为研究

采用胶晶模板法制备了一系列具有三维有序大孔结构的氧化铁和氧化铁-二氧化硅复合脱硫剂,并采用固定床动态实验考察了其中温脱硫性能及其再生行为。硫化前后样品采用X射线衍射仪(XRD)、N_2吸附、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术进行了表征。结果表明,与三维有序大孔氧化铁脱硫剂相比,脱硫剂中引入SiO_2可以极大地提高脱硫剂的比表面积和Fe_2O_3的分散性,并且可以减小Fe_2O_3的晶粒尺寸,进而有利于提高脱硫剂的脱硫精度和脱硫性能。另外,脱硫剂的脱硫性能与PS微球的直径和硫化温度有关,样品的脱硫性能随着PS微球直径的增大和硫化温度的升高均呈现先增大后减小的趋势。当PS微球直径为175 nm,脱硫温度为300℃时,脱硫剂的硫容最优,其穿透硫容和饱和硫容分别为51.6%和73.2%。再生实验结果表明,三维有序大孔结构可以极大地降低样品的再生温度,样品的最佳再生温度为300℃。     

高温煤气脱硫剂的研究

介绍了高温煤气脱硫剂的研制、脱硫工艺条件试验、再生工艺条件试验和长周期考核试验。结果表明,以锌、锰和铁等氧化物为主成分,辅加多种助剂的高温煤气脱硫剂,可在(350～600)℃脱除煤气中的H_2S和COS,脱硫精度高,硫容大,脱硫剂脱硫后可再生。脱硫剂经22次脱硫-再生循环操作后,仍具有高脱硫性能。     

类水滑石衍生锌基复合氧化物的硫化再生行为

通过共沉淀法合成了具有片状堆积结构的类水滑石衍生锌基（钴或镍掺杂）复合金属氧化物,并将其用于中高温煤气脱硫。本文采用X射线衍射（XRD）、扫描电子显微镜（SEM）分析了脱硫剂及其前体的物相组成与形貌织构,发现镍（或钴）掺杂后脱硫剂的主要晶相仍为具有六方纤锌矿结构的氧化锌,且镍（或钴）的引入并未明显改变锌铝复合氧化物及其类水滑石前体的形貌结构。在固定床评价装置上研究了脱硫剂的硫化与再生行为,研究表明,锌镍（或钴）摩尔比为20时对应的掺杂型脱硫剂穿透时间（324min）最长,硫容（25.4%）最高。与未掺杂脱硫剂相比,掺杂镍（或钴）的脱硫剂最佳再生温度降低60℃左右。引入镍（或钴）后,脱硫剂不仅在多次硫化再生循环过程中维持高硫容,而且仍具有片状结构,硫化再生循环稳定性显著增强。     

锌基合成气深度精脱硫剂开发及性能分析

以锌基材料为主要组分,采用共沉淀法及混捏法制备级配组合的深度精脱硫剂,采用XRF、XRD、氮吸附法对试验前后的脱硫剂进行表征。结果表明,金属氧化物对H₂S的脱硫精度顺序为CuO>ZnO>NiO>CaO>MnO>Fe₃O₄>MgO;共沉淀法制备的深度精脱硫剂CuO和ZnO的平均晶粒分别为10.1 nm和9.1 nm,不同挤条压力下混捏法制备的精脱硫剂ZnO晶粒大小不同;高温可提高锌基精脱硫剂活性组分的利用率;脱硫剂的硫容分别为36.35%、32.91%、33.05%、19.52%时,相对应的活性组分的利用率分别为96.5%、92.60%、93.54%、75.1%;使用后精脱硫剂的孔容、比表面积均大幅下降,但最可几孔径、平均孔径变化较小,同时表明大孔容、高比表面积、大孔径更有利于提高脱硫剂的脱硫反应活性、硫容和活性组分的利用率。     

半焦负载铁基脱硫剂及其焦炉煤气脱硫特性

对超声波辅助浸渍法制备褐煤半焦为载体的Fe及Fe-Cu脱硫剂可行性进行了研究,考察了脱硫剂最佳制备工艺和硫化温度对脱硫剂硫化性能的影响.通过X射线衍射仪(XRD)及带有能谱分析的电子扫描显微镜(SEM-EDS)分析硫化前后脱硫剂的晶体结构和表面形貌的变化,利用傅立叶红外仪(FTIR)分析表征脱硫前后的脱硫剂官能团变化.结果表明,当超声清洗器功率为100 W时,制取脱硫剂的最佳条件是超声浸渍时间为5h,共沉淀时间为3h,超声波水浴温度为60℃.活性半焦负载的脱硫剂能够有效脱除焦炉煤气中的H2S和COS.随着硫化温度的升高,穿透时间和硫容均增加,在脱硫温度为400℃时具有最大的穿透硫容和穿透时间,且Cu元素的加入使半焦负载的铁基脱硫剂脱硫效果明显增强.     

Desulfurization performance of iron-manganese-based sorbent for hot coal gas

A series of iron-manganese-based sorbents were prepared by co-precipitation and physical mixing method, and used for H₂S removal from hot coal gas. The sulfidation tests were carried out in a fixed-bed reactor with space velocity of 2000 h⁻¹(STP). The results show that the suitable addition of manganese oxide in iron-based sorbent can decrease H₂S and COS concentration in exit before breakthrough due to its simultaneous reaction capability with H₂S and COS. Fe₃O₄ and MnO are the initial active components in iron-manganese-based sorbent, and FeO and Fe are active components formed by reduction during sulfidation. The crystal phases of iron affect obviously their desulfurization capacity. The reducibility of sorbent changes with the content of MnO in sorbent. S7F3M and S3F7M have bigger sulfur capacities (32.68 and 32.30 gS/100 g total active component), while S5F5M has smaller sulfur capacity (21.92 gS/100 g total active component). S7F3M sorbent has stable sulfidation performance in three sulfidation-regeneration cycles and no apparent structure degradation. The sulfidation performance of iron-manganese-based sorbent is also related with its specific surface area and pore volume.     

Correlation of H<Subscript>2</Subscript>S and COS in the hot coal gas stream and its importance for high temperature desulfurization

Thermodynamic analysis of the correlation of H₂S and COS has been carried out at the temperature range of 400–650 °C at which high temperature desulfurization of coal gas is usually performed. The correlation of the two sulfur species is mainly through the reaction H₂S+CO→COS+H₂. Simulated coal gas with the following composition CO 32.69%, H₂ 39.58%, CO₂ 18.27%, N₂ 8.92% and H₂S 0.47% was used in this study, and the equilibrium concentrations of the two species at different temperatures were calculated. The results of Fe-based sorbents during sulfidation were compared with calculations. It is concluded that the above reaction may reach equilibrium concentration in the presence of the Fe-based sorbents, which means the Fe-based sorbents may effectively catalyze the reaction between H₂S and CO. Because of the correlation of the two sulfur species, both can be effectively removed at high temperatures simultaneously, offering high temperature desulfurization some advantages over low temperature desulfurization processes.     

A kinetic study on medium temperature desulfurization using a natural manganese ore

Natural manganese ores were selected as raw materials for the desulfurization sorbent because of economical efficiency and high reactivity on hydrogen sulfide. Initial reaction rates between H₂S and desulfurization sorbent of natural manganese ores were determined in a temperature range of 400-800°C using a thermobalance reactor. All reactions were first order with respect to H₂S and were expressed by the Arrhenius relation. When the sulfidation reaction was controlled by diffusion, the temperature dependence of the effective diffusivity was given by the Arrhenius equation. Activation energies and frequency factors were obtained from the product layer diffusion coefficient of various sorbents by plotting as an Arrhenius equation form. Several additives were mixed to improve the sulfidation capacity, and NiO was the best additive.     

Desulfurization matching with coal poly-generation system based on dual gas resources

The coal poly-generation system for the production of alcohol and ether fuels as well as power is one of advanced coal utilization techniques. The team leaded by Professor Xie Kechang is carrying out the research on the poly-generation system to produce the syngas from the combination of gasified and pyrolyzed coal gas (dual gas resources) for the alcohol ether synthesis. Gas desulfurization is one of the key technologies for this system. The desulfurization matching with dual gas resources based poly-generation system for the production of alcohol and ether fuels as well as power is presented according to gas components, sulfur content, sulfur species and desulfurization accuracy in this technology. This matching desulfurization is classified into hot gas desulfurization, normal gas desulfurization, warm gas desulfurization and organic sulfur catalytic conversion. The preparation of H₂S removal sorbents, organic sulfur hydrolysis catalyst and the evaluation of their activities involved in the system were investigated. The H₂S removal efficiencies of the crude and fine desulfurization sorbents prepared for hot gas desulfurization are 90% and 99% at 500 °C in simulating coal gas, and their sulfur capacities are 21.85 wt.% and 24.91 wt.%, respectively. The organic sulfur catalyst shows the high hydrolysis activity, and the hydrolysis conversion of COS is more than that of CS₂ on the same catalyst. The research will provide necessary information for the matching desulfurization technology in the demonstration project on dual gas resources coal poly-generation system.     

Reactivity of Metal Oxide Sorbents for Removal of Sulfur Compounds from Coal Gases at High Temperature and Pressure

Abstract

Hot-gas desulfurization for the integrated gasification combined cycle (IGCC) process has been investigated to effectively remove hydrogen sulfide with various metal oxide sorbents at high temperatures and pressures. Metal oxide sorbents such as zinc titanate oxide, zinc ferrite oxide, copper oxide, manganese oxide, and calcium oxide were found to be promising sorbents in comparison with other removal methods such as membrane separation and reactive membrane separation. The removal reaction of H₂S from coal gas mixtures with zinc titanate oxide sorbents was conducted in a batch reactor. The main objectives of this research are to formulate promising metal oxide sorbents for removal of hydrogen sulfide from coal gas mixtures, to compare reactivity of a formulated sorbent with a sorbent supplied by the Research Triangle Institute at high temperatures and pressures, and to determine effects of concentrations of moisture contained in coal gas mixtures, and to determine effects of concentrations of moisture contained in coal gas mixtures on equilibrium absorption of H₂S into metal oxide sorbents. Promising durable metal oxide sorbents with high-sulfur-absorbing capacity were formulated by mixing active metal oxide powders with inert metal oxide powders and calcining these powder mixtures.     

New development of zinc-based sorbents for hot gas desulfurization

This paper introduced two new zinc-based sorbents for hot gas desulfurization, G-201 and G-202. Evaluation tests proved that both G-201 and G-202 sorbents had good performance in desulfurization. They could reduce H₂S concentration from about 10 g/m³ in coal gas to less than 20 mg/m³. In addition, the sulfur capacity of both sorbents increased with temperature rising. No decrease in sulfur capacity of G-201 occurred during 20-desulfurization/regeneration cycle tests, whose calculated value was 19.43–24.23 g/100 g sorbent. G-201 sorbent passed a 1500 h real hot gas desulfurization test in a fixed-bed PDU. No occurence of striping, attrition and sintering on the surface of used sorbents was found after the long-time test. The reactivity was stable and the sulfur capacity is 21.19 g/100 g sorbent after the 1500 h test.     

Preparation and selection of Fe-Cu sorbent for COS removal in syngas

A series of iron-based sorbents prepared with iron trioxide hydrate, cupric oxide by a novel method was studied in a fixed-bed reactor for COS removal from syngas at moderate temperature. In addition, the sorbents mixed with various additives in different ratios were tested. The effects of additive type and ratio on the breakthrough capacity and desulfurization performance, as well as the influence of operating conditions on sulfidation behavior of the sorbent, were investigated. The simulate gas contained 1% COS, 5% CO₂, 20%–30% CO and 60%–70% H₂. The outlet gases from the fixed-bed reactor were automatically analyzed by on-line mass spectrometry, and the COS concentration before breakthrough can be kept steady at 1 ppmv. The result shows that the breakthrough sulfur capacity of the sorbent is as high as 25 g-S/100 g. At 700 K and space velocity of 1000 h⁻¹, the efficiency of sulfur removal and breakthrough sulfur capacity of the sorbent increase with the increase of copper oxide with an optimum value. The result shows that the species and content of additives also affect desulfurization performance of the sorbent.     

Investigation of NH3 Influence on Adsorptive H2S Removal from Biogas for Solid Oxide Fuel Cell Application

The generation of electrical energy from biogas is state of the art. One option is the application of fuel cells for generating electrical energy. Due to their construction, the materials used and their mode of operation, solid oxide fuel cells (SOFCs) are particularly suitable. The primary problem in the operation of SOFCs using biogas is H₂S. The goal of this work is to investigate the possible effects of ammonia on different sorbents that have already successfully been used for the desulfurization of biogas. The H₂S adsorption capacity of four commercially available sorbents in the presence of NH₃ was investigated as well as the influence of an upstream NH₃ removal. The CuO‐MnO‐based sorbent showed the best performance related to sulfur uptake.     

Removal of sulfur at high temperatures using iron-based sorbents supported on fine coal ash

This paper deals with the simultaneous removal of H₂S and COS in the temperature range of 400-650 °C at 1 bar by using iron-based sorbents. The iron-based sorbents were prepared using iron oxide and cerium oxide with coal fine ash as the support. Simulated coal gas was used in the sulfidation experiments and 5% O₂ in N₂ gas was used for regeneration of sorbents. Both sulfidation and regeneration experiments have been carried out using a fixed-bed quartz reactor. The product gases were analyzed using a GC equipped with a TCD and a FPD. The results demonstrated that both H₂S and COS can be effectively reduced using the iron-based sorbents supported on fine coal ash. XRD analysis shows that Fe_1−xS phase has formed during sulfidation indicating a high sulfur capacity of the sorbent. The mechanism of the removal of COS simultaneously with H₂S is also discussed.     

Modified Semi‐Coke‐Supported Cerium Oxide‐Doped Zinc Ferrites for the Removal of H2S from Coal Gas

Cerium oxide‐doped ZnFe₂O₄ sorbents supported on modified semi‐coke (MSC) were prepared to improve the desulfurization efficiency of zinc ferrites. The sulfidation tests of the ZnFe₂O₄/MSC sorbents with and without Ce were carried out using a fixed‐bed reactor at 450 °C. The effect of the CeO₂/ZnFe₂O₄ molar ratio of the sorbents on the sulfur capacity was studied. The characteristics of the sorbents were analyzed by X‐ray diffraction, N₂ adsorption, scanning electron microscopy and X‐ray photoelectron spectroscopy. The results showed that cerium oxide could greatly improve the desulfurization reactivity of the ZnFe₂O₄/MSC sorbents. The molar ratio of Ce to Zn and Fe influences the desulfurization reactivity, and a good sulfur capacity of the sorbent can be obtained with a Ce/Zn/Fe ratio of 4:4:1. It was also found that the addition of CeO₂ could enlarge the surface area and the pore volume, thus improving the dispersion of active components. Ce doping results in an increment of the oxygen adsorbed on the sorbent surface, which facilitates the adsorption of H₂S. The Ce ions could act as carriers of the oxidation and reduction reactions and the oxygen transfer could be accelerated during the desulfurization process of coal gas.