制备方法对中高温煤气脱硫剂性能的影响

随着中高温煤气脱硫技术的发展.脱硫剂的制备方法也呈现出多种形式,日前主要有机械共混法、浸渍法、沉淀法、溶胶凝胶法等.脱硫剂的制备方法直接影响着其物化性能.本文对中高温煤气脱硫剂制备方法进行了总结,基于不同活性组分种的硫化/再生反应性与不同方法所制备脱硫剂的粒径及表面特性对比分析了各类方法的优缺点,归纳出适合于不同硫化条件所使用脱硫剜的制备方法.     

高温煤气脱硫剂再生性能研究进展

金属复合型脱硫剂已经成为高温煤气脱硫剂的研究重点,脱硫剂不仅要求具有良好的硫化能力,还必须易于再生,以达到多次循环使用及降低生产成本的目的。介绍了中高温煤气脱硫剂的再生性能的研究概况,包括:铁和锌系列脱硫剂、钙和铈系列脱硫剂、铜和锰系列脱硫剂。大量实验研究表明,脱硫剂的种类和再生工艺与其再生后的脱硫特性密切相关,再生结果是脱硫剂能否工业化应用的关键环节之一,在考察脱硫剂硫化特性的同时,必须注重脱硫剂再生特性的研究。     

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.     

负载型氧化锌脱硫剂脱硫性能的改善

单一氧化锌负载型脱硫剂脱硫精度可达到0.1×10-6,但其硫容量相对较低.采用共浸渍法制备ZnO-MnO2/γ-Al2O3负载型H2S脱硫剂,通过XRD和BET等手段研究了MnO2对脱硫剂物相及比表面积的影响.并在固定床反应器中考察了Zn/Mn摩尔比、负载量、烧结温度和脱硫温度对脱硫性能的影响.结果表明,活性组分锌锰摩尔比为8∶1,负载量为20％的脱硫剂有较好的脱硫性能,脱硫精度小于0.1×10-6的同时,最高硫容量可达19.08 g S/100 g(ZnO-MnO2).MnO2的加入可以明显改善氧化锌负载型脱硫剂的脱硫性能.     

Effect of sulfidation/oxidative regeneration cycle on the solid structural changes of sorbent for high-temperature removal of H2S

In order to investigate the effects of sulfidation/oxidative regeneration cycle on the change of structural properties and removal capacity of sorbent, sulfidation/regeneration cycle was carried out up to 15 times in a fixed-bed reactor. The effluent gases from the fixed-bed reactor were analyzed by gas chromatography, and XRD, SEM, and liquid nitrogen physisorption method were used to characterize the reacted sorbents. The sorbent treated first sulfidation/regeneration cycle exhibited maximum specific surface area and the highest H₂S removal capacity. Hysteresis of adsorption isotherm of the regenerated sorbent reflected the growth of pores of fresh sorbent and pore size distribution confirmed this fact. Furthermore constant H₂S removal capacity was maintained up to 15 times of sulfidation/regeneration cycle.     

Kinetic behaviour of iron oxide sorbent in hot gas desulfurization

Although a number of reports on sorbents containing ZnO for H₂S removal from coal-derived gases can be found in the literature, it is shown in our study that a special sorbent containing Fe₂O₃·FeO (SFO) with minor promoters (Al₂O₃, K₂O, and CaO) as the main active species is more attractive for both sulfidation and regeneration stages, also under economic considerations. This paper presents the kinetic behaviour of SFO in a hot gas desulfurization process using a thermogravimetric analysis under isothermal condition in the operating range between 500 and 800 °C. The gas stream was N₂ with a 2% wt of H₂S. Experiences carried out on sorbent sulfidation with SFO (particle sizes in the range of 0.042-0.12 mm) indicate that the sorbent sulfidation capacity sharply increases with temperature in the range of 500-600 °C. It is also shown that the sample weight reaches its maximum absorption capacity, near saturation, at 600 °C so that it makes no sense to increase the sulfidation temperature from this point. To make a comparison between SFO and a zinc titanate based sorbent, a set of sulfidation tests was carried out at 600 °C during 7200 s using the same sieve range for both sorbents between 42 and 90 μm. Results show that the sulfidation capacity of SFO is 1.9 times higher than that of zinc titanate.     

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.     

Novel‐doped zinc oxide sorbents for low temperature regenerable desulfurization applications

Eight metal oxide sorbents including transition metal doped ZnO/SiO₂ sorbents and ZnO/SiO₂ were prepared by incipient wetness impregnation for regenerable desulfurization applications at low temperatures (i.e. room temperature). Among them, copper‐doped sorbent (Cu‐ZnO/SiO₂) demonstrated the highest saturation sulfur capacity of 0.213 g sulfur/g ZnO (54% of the theoretical capacity), which is twice that of ZnO/SiO₂ sorbent. Compared with ZnO/SiO₂, Cu‐ZnO/SiO₂ demonstrated superior desulfurization performance in a wide temperature range of 20–400°C. Due to the use of porous SiO₂ support, Cu‐ZnO/SiO₂ is highly regenerable. It can be easily regenerated in air at low temperatures, ca. 300–550°C, which are much lower than the typical regeneration temperatures of commercial ZnO sorbents. Cu‐ZnO/SiO₂ maintained its sulfur capacity during 10 cycles of regeneration/sulfidation. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

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.     

磷添加方式对NiMo/Al2O3催化剂加氢脱硫性能的影响

采用分步浸渍法制备了不同磷添加方式改性的NiMo/Al₂O₃催化剂,在固定床微反装置上考察了该系列催化剂对焦炉煤气中噻吩加氢脱硫（HDS）性能的影响,采用BET、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、NH₃程序升温脱附（NH₃-TPD）、C₄H₄S(H₂)程序升温脱附[C₄H₄S(H₂)-TPD]、X射线光电子能谱（XPS）、高清透射电镜（HRTEM）和拉曼（Raman）等分析手段对催化剂进行表征。结果表明,不同磷添加方式制备NiMo/Al₂O₃催化剂的HDS性能存在较大差异。其中,催化剂PNi-Mo/Al和PMo-Ni/Al表面弱吸附解离活性位增强,对焦炉煤气中噻吩有较好的低温加氢脱硫活性,以含292.5mg/m³噻吩的模拟焦炉煤气为原料时,PNi-Mo/Al在250℃下对噻吩的脱硫率达61%。对于PNi-Mo/Al和PMo-Ni/Al催化剂,先浸渍P、Ni或者P、Mo时,P优先和载体Al₂O₃作用,减弱了活性金属组分Ni、Mo与载体间的相互作用,而又防止Ni或者Mo与载体间相互作用过低而聚集,提高了Ni、Mo在载体表面的均匀分散,生成能够促进硫化形成Ⅱ型活性相Ni-Mo-S的NiMoO₄物种。NiMoO₄和MoO₃之间的协同作用提高了催化剂的硫化度,使HDS活性得以提高。     

A study of the sulfidation and regeneration reaction cycles of Zn-Ti-based sorbents with different crystal structures

The reaction cycles of the sulfidation and regeneration of Zn-Ti-based sorbents prepared by a physical mixing method (ZT-700 and ZT-1000) or co-precipitation method (ZT-cp) were tested in a fixed bed micro-reactor at middle temperature (Sulfidation; 480 °C, regeneration; 580 °C). The ZnS produced during sulfidation from the Zn₂TiO₄ with a spinel structure (ZT-1000, ZT-cp) was easily regenerated even at 550 °C, while the ZnS produced from the ZnO with a hexagonal structure (ZT-700) needed a temperature higher than 610 °C. After regeneration, each sorbent was restored to its original crystal structure. The differences in the regeneration properties and the reaction cycles of the sorbents were related to the original crystal structures rather than to the physical properties such as pore volume and surface area. To study these differences further, FT-IR, FT-Raman, XRD and TPR were used, and their results including the reaction cycles of the sulfidation and regeneration on the Zn-Ti based sorbents with different crystal structures were discussed.     

高温煤气金属脱硫剂的研究进展

煤的清洁转化利用符合中国的能源结构,高温煤气脱硫是提高能源利用率的关键技术。本文综述了单一金属氧化物和复合金属氧化物干法脱除H2S的研究进展,对比分析了单一金属氧化物在脱硫效率、使用温度和再生方面的优缺点,指出由于单一金属氧化物脱硫剂不能满足实际生产需要,因此兼有单一金属氧化物优点的复合金属脱硫剂成为未来研究方向。同时,论述了复合金属脱硫剂的制备原则、脱硫效率及再生等方面的研究状况。在此基础上,重点对铁酸锌和钛酸锌两种具有代表性的复合脱硫剂及其他复合金属脱硫剂进行了介绍。     

铝基铜干法烟气脱硫剂制备及脱硫再生实验

采用浸渍法制备了铝基铜脱硫剂,考察了制备过程中浸渍液浓度对脱硫剂脱硫性能的影响,同时对制得的脱硫剂进行了循环烟气脱硫-再生实验,分析了脱硫剂的表面微观结构在脱硫和再生过程中的变化.实验和分析表明,制得的铝基铜脱硫剂具有较高的脱硫效率,使用该脱硫剂进行循环烟气脱硫的性能是稳定的.     

不同前驱体对中温铁基脱硫剂性能的影响

分别以硝酸铁和草酸铁分解产物及分析纯氧化铁为活性组分进行脱硫剂制备,在固定床活性评价装置上对其硫化性能进行考察。结果表明,CF750、NF750和F750脱硫剂的孔结构和比表面积相差不大,但以硝酸铁和草酸铁为前驱体分解得到的活性组分粒径小于氧化铁,硝酸铁和草酸铁分解产物制备的脱硫剂对H_2S的脱除活性优于分析纯氧化铁,脱硫剂对硫化过程中出现的COS具有相同的脱除规律,硝酸钾的改性提高了脱硫剂的还原温度,减弱了CO_2与H_2S的竞争吸附能力,抑制了CO的歧化反应,有利于H_2S和COS脱除能力的改善。     

微波固相法制备铁酸锌脱硫剂的硫化动力学

通过微波与常规固相法制备了铁酸锌高温煤气脱硫剂,使用X射线衍射（XRD）、氮吸附、扫描电子显微镜（SEM）以及X射线光电子能谱（XPS）对两种不同焙烧方式制备的脱硫剂的物相组成、织构形貌和表面元素进行了表征。数据显示微波焙烧制备的脱硫剂具有孔隙结构丰富、表面金属元素含量高、结合能低等优点。使用热天平对铁酸锌脱硫剂硫化行为进行了研究,根据等效粒子模型计算了两种脱硫剂与硫化氢气体反应的动力学参数,得到了硫化反应动力学方程,并在固定床上对其煤气脱硫性能进行了考察。结果表明硫化过程分为化学反应控制区和颗粒内扩散控制区。微波焙烧制备脱硫剂的化学反应活化能和颗粒内扩散活化能较低,说明其在硫化氢气体脱除上具有更高的活性。在模拟煤气气氛下,相比常规焙烧方法制备的脱硫剂,微波制备的脱硫剂的脱硫性能显著提高,具有更高的硫容和更长的精脱硫时间。     

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.     

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。     

低压力降新型填料在焦炉煤气PDS脱硫塔的应用

分析了焦炉煤气脱硫塔采用的填料的特性,提出焦炉煤气脱硫采用低压力降新型填料的技术方案,在不影响焦炉煤气脱硫效果的条件下,降低了脱硫塔的阻力。     

Simultaneous experiments of sulfidation and regeneration in two pressurized fluidized-bed reactors for hot gas desulfurization of IGCC

Hot Gas Desulfurizarion for IGCC is a new method to efficiently remove H2S in fuel gas with regenerable sorbents at high temperature and high-pressure conditions. The Korea Institute of Energy Research did operation of sulfidation in a desulfurizer and regeneration in a regenerator simultaneously at high pressure and high temperature conditions. The H₂S concentration at exit was maintained continuously below 50ppmv at 11,000 ppmv of inlet H₂S concentration. The sorbent had little effect on the reducing power in the inlet gas in the range from 11% to 33% of H₂. As inlet H₂S concentration was increased, H₂S concentration in the product gas was also increased linearly. The sorbent was maintained at low sulfur level by the continuous regeneration and the continuous solid circulation at the rate of 1.58× 10⁻³ kg/s with little mean particle size change.     

H2S removal and regeneration properties of Zn–Al-based sorbents promoted with various promoters

In order to improve the poor regeneration properties of the ZnO–Al₂O₃ (ZA)sorbent with a high sulfur removing capacity and fast H₂S absorption rate, 5–10 wt.% of various additives such as iron (Fe₂O₃), cobalt (Co₃O₄), nickel (NiO) and cerium oxide (CeO₂) were added to the ZA sorbent. These sorbents were prepared by the co-precipitation method and their sulfur removing capacities and regeneration properties were measured in a fixed-bed reactor during multiple cycles at middle-temperature ranges between 480 and 580 °C. The sulfur removing capacities of these sorbents measured 0.17–0.20 g S/g sorbent, which corresponded to 80% of the theoretical value and the values were maintained to within 10 cycles. The poor regeneration property of the ZA sorbent, which needed a long time (600 min), was also improved by addition of these promoters. These sorbents were regenerated completely within 300 min. The additives such as Fe, Co and Ni formed their aluminates, which did not change into sulfide form during sulfidation. The additives/aluminates played an important role in transforming S in ZnS into SO₂. Cerium dioxide showed a similar role with such aluminates in the oxidation of sulfur. The catalytic roles of the promoters and the changes in the physical properties of sorbents, during multiple cyclic tests, are discussed.