Regeneration of Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-based high-temperature coal gas desulfurization sorbent in atmosphere with sulfur dioxide

Regeneration of a high-temperature coal gas desulfurization sorbent is a key technology in its industrial applications. A Fe₂O₃-based high-temperature coal gas desulfurizer was prepared using red mud from steel factory. The influences of regeneration temperature, space velocity and regeneration gas concentration in SO₂ atmosphere on regeneration performances of the desulfurization sorbent were tested in a fixed bed reactor. The changes of phase and the composition of the Fe₂O₃-based high-temperature coal gas desulfurization sorbent before and after regeneration were examined by X-ray diffraction (XRD) and X-ray Photoelectron spectroscopy(XPS), and the changes of pore structure were characterized by the mercury intrusion method. The results show that the major products are Fe₃O₄ and elemental sulfur; the influences of regeneration temperature, space velocity and SO₂ concentration in inlet on regeneration performances and the changes of pore structure of the desulfurization sorbent before and after regeneration are visible. The desulfurization sorbent cannot be regenerated at 500°C in SO₂ atmosphere. Within the range of 600°C–800°C, the time of regeneration becomes shorter, and the regeneration conversion increases as the temperature rises. The time of regeneration also becomes shorter, and the elemental sulfur content of tail gas increases as the SO₂ concentration in inlet is increased. The increase in space velocity enhances the reactive course; the best VSP is 6000 h^?1 for regeneration conversion. At 800°C, 20 vol-% SO₂ and 6000 h^?1, the regeneration conversion can reach nearly to 90%.     

Reactivity of copper oxide-based sorbent in coal gas desulfurization

Various CuO-based sorbents were prepared to investigate effects of sorbent ingredients such as SiO₂, MnO₂, and MoO₃ on desulfurization reactivity. Several candidate sorbents chosen from a TGA screening test were further tested in a microreactor system. The amount of SiO₂ support to minimize sintering of sorbents was 25 wt%. Sulfur loading was seriously affected by the amount of additives (MnO₂, MoO₃) in a multi-cycle test. Improvement of sulfur loading by the additives was observed in the multi-cycle test. Effects of support materials on sulfur loading were also investigated by using SiO₂, g-alumina and zeolite. SiO₂ showed the best performance among the support candidates. The sorbent showing the best sulfur loading ability was CMS6 (CuO :MoO₃ : MnO₂ : SiO₂=61 : 11 : 3 : 25). Its sulfur loading reached up to 13.8 g sulfur/100 g sorbent in a multi-cycle test.     

高温煤气脱硫剂再生行为气氛效应的研究进展

脱硫剂再生过程是高温煤气脱硫工业化应用必备的关键环节之一。本文重点综述了含氧气氛、水气氛、水氧混合气氛和二氧化硫气氛中高温煤气脱硫剂的再生行为。以硫资源化回收作为高温煤气脱硫剂再生的目标,分析了不同再生气氛以及不同再生操作条件对高温煤气脱硫剂再生行为的影响。最后对今后高温煤气脱硫剂的再生研究提出了几点建议。     

T305型脱硫剂在半水煤气脱硫中的应用

介绍了T305型脱硫剂在半水煤气脱硫中的应用，并分析了脱硫床层吸硫分布曲线及脱硫剂的利用率，说明该脱硫剂对CO含量较高的半水煤气仍能达到较理想的脱硫效果。     

Fe2+液相催化氧化脱除烟气中SO2

提出了一种烟气脱硫新工艺。实验选用水作脱硫剂 ,在只以Fe为催化剂的条件下进行。加入吸收液槽中的铁屑可与脱硫产生的稀硫酸进行反应 ,不仅可维持较高的吸收液pH值 ,而且产生的Fe2 + 引发了液相催化氧化SO2 反应。连续运行实验结果表明脱硫过程在不同阶段分别受SO2 溶解、Fe2 + 液相催化氧化SO2 反应、气相中SO2 扩散和铁屑与酸反应控制。吸收液中Fe2 + 质量浓度的变化和初始Fe2 + 质量浓度对脱硫率及吸收液pH值影响显示 ,可直接由清水制取高浓度硫酸亚铁溶液。实验还调查了SO2 入口质量浓度、液气比、空塔气速和吸收温度对脱硫率和吸收液pH值的影响     

Recent progress of Ga2O3-based gas sensors

In recent years, gas sensors fabricated from gallium oxide (Ga₂O₃) materials have aroused intense research interest due to the superior material properties of large dielectric constant, good thermal and chemical stability, excellent electrical properties, and good gas sensing. Over the past decades, Ga₂O₃-based gas sensors experienced rapid development. The long-term stable Ga₂O₃-based gas sensors for detecting oxygen and carbon monoxide have been commercialized and renowned with extremely good gas sensing characteristics. Recent pioneering studies also exhibit that the Ga₂O₃-based gas sensors possess great potentials in applications of detecting nitrogen oxides, hydrogen, volatile organic compounds and ammonia gases. This article presents recent advances in gas sensing mechanism, device performance parameters, influence factors, and applications of Ga₂O₃-based gas sensors. The impacts of influence factors, doping, material structure and device structure on the performance of gas sensors are discussed in detail. Finally, a brief overview of challenges and opportunities for the Ga₂O₃-based gas sensors is presented.     

ZnO-enhanced In2O3-based sensors for n-butanol gas

A series of high-response and fast-response/recovery n-butanol gas sensors was fabricated by adding ZnO to In₂O₃ in varying molar ratios to form ZnO-In₂O₃ nanocomposites via a facile co-precipitation hydrothermal method. Morphological characterizations revealed that the shape of pure In₂O₃ was changed from irregular cubes into irregular nanoparticles, 30–50?nm in size, with the addition of ZnO. Compared with the pure In₂O₃ gas sensor, the ZnO-In₂O₃ gas sensor exhibits superior n-butanol sensing performance. With the introduction of ZnO, the response of the sensor to n-butanol was improved from 17 to 99.5 at 180?°C for a [Zn]:[In] molar ratio of 1:1. In addition, the ZnO-In₂O₃ gas sensors show a reduced optimal working temperature, excellent selectivity to n-butanol, and good repeatability. The response of the ZnO-enhanced In₂O₃-based sensors showed a strong linear relationship with the n-butanol gas concentration, allowing for the quantitative detection of n-butanol gas.     

高硫煤还原磷石膏制SO2

在N2气氛下研究了高硫煤还原磷石膏的热分解反应特性,利用烟气分析仪分析析出的气体成分。研究了不同颗粒尺寸的高硫煤对磷石膏分解的影响,结果表明,高硫煤颗粒尺寸在97—147μm有利于磷石膏分解制SO2的反应。研究还发现原料摩尔比对磷石膏的反应历程有显著的影响,当摩尔比为1∶1.96时,磷石膏还原分解的固体产物有CaS和CaO;当摩尔比降为1∶1.18时,固体产物中CaO大量增加,而仅有少量CaS存在;当摩尔比降到1∶0.98时,固体产物中除了CaO和CaS外,还发现了未反应完的CaSO4。所以摩尔比在1∶1.18时有利于高硫煤还原磷石膏制SO2。     

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.     

Kinetic studies on the reactions involved in the hot gas desulfurization using a regenerable iron oxide sorbent—II: Reactions of iron sulfide with oxygen and sulfur dioxide

In the hot gas desulfurization process using iron oxide sorbent, the regeneration of the sulfided iron oxide sorbent consists of two reactions: the oxidation of iron sulfide with air, and its reaction with the sulfur dioxide formed during the air oxidation. This part describes the kinetic studies on the reactions of iron sulfide (formed by the reactions of Fe₂O₃ with H₂CO mixture and subsequendy with H₂S) with oxygen and sulfur dioxide. The experimental and analysis procedures used are similar to those outlined in Part I of this paper.The activation energies for the oxygen and the sulfur dioxide reactions are found to be 15.63 and 17.5 kcal/mol, respectively. Notably, the product oxides formed in the two cases are different. With air, the reaction is fast and the final product is Fe₂O₃, whereas with SO₂, the major product is Fe₃O₄, which slowly oxidizes to Fe₂O₃ in a secondary step. Also, in the latter reaction elemental sulfur is formed.     

三氧化二铁晶型对铁铬系高温变换催化剂性能的影响

以硝酸亚铁为原料,采用共沉淀法分别制备了α型、γ型和非晶体型3类晶型的Fe2O3高温变换催化剂,并对所制备催化剂的性能进行了对比评价.结果表明①Fe2O3的晶型对变换催化剂的性能有较大的影响.尽管γ-Fe2O3晶型催化剂比α-Fe2O3晶型催化剂具有更高的初始活性,但其结构的不稳定性造成催化剂强度低、密度大和耐热性能差的缺点;②非晶体型态Fe2O3极小的微观粒子尺寸和宏观上的非晶态物质"异向同性"特性,使得所制备催化剂具有较大的比表面积、相对低的密度、高强度、高耐热性和更高的活性稳定性等优点;③非晶体型态Fe2O3催化剂的综合性能最高,α-Fe2O3晶型的次之,而γ-Fe2O3晶型的综合性能最低.其中,非晶体型态Fe2O3催化剂在比γ-Fe2O3晶型催化剂强度提高30%的情况下,堆密度可降低15%左右,且其耐热后的活性(CO变换率)比γ-Fe2O3型催化剂提高6个百分点.     

响应面法优化氧化锌中高温煤气脱硫剂的制备工艺

通过优化制备工艺和制备条件,提高氧化锌脱硫剂的脱硫性能。以乙二酸和乙酸锌为原料,采用固相法制备了乙二酸锌前驱体;添加助剂和粘结剂后,通过微波焙烧制备了氧化锌中高温煤气脱硫剂。采用单因素法研究了微波功率、焙烧温度、焙烧时间以及活性组分质量分数对脱硫剂性能的影响,并利用响应面法探讨了各因素及其交互作用对脱硫剂穿透时间和硫容的影响,确定了氧化锌脱硫剂的最佳制备工艺:微波功率1 300 W,焙烧温度550℃,焙烧时间60 min,活性组分质量分数30%。采用回归分析法建立了回归模型,并通过试验验证了模型的可靠性。结果表明:模型预测值与实测值接近;焙烧温度、焙烧时间和活性组分质量分数对脱硫剂穿透时间有显著的影响;焙烧温度和焙烧时间、焙烧温度和活性组分质量分数二者的交互作用均比较显著。     

Dehydrogenation of ethylbenzene to styrene over Fe2O3/Al2O3 catalysts in the presence of carbon dioxide

Thermodynamic consideration of the dehydrogenation of ethylbenzene clearly indicates that the equilibrium yield of styrene for the dehydrogenation in the presence of CO₂ is much higher than that for the dehydrogenation in the presence of steam. A two-step pathway for the dehydrogenation in the presence of CO₂ appears to provide higher equilibrium yield of styrene at a given temperature. The amount of energy required for the new process using CO₂ is much lower than that for a typical present commercial process using steam. An Fe₂O₃(10 wt.%)/Al₂O₃(90 wt.%) catalyst prepared by a coprecipitation method was found to be effective for the dehydrogenation of ethylbenzene to produce styrene in the presence of CO₂.     

Dehydrogenation of ethylbenzene to styrene over Fe2O3/Al2O3 catalysts in the presence of carbon dioxide

An Fe₂O₃ (10 wt%)/Al₂O₃ (90 wt%) catalyst prepared by a coprecipitation method was found to be effective for dehydrogenation of ethylbenzene to produce styrene in the presence of CO₂ instead of steam used in commercial processes. The dehydrogenation of ethylbenzene over the catalyst in the presence of CO₂ was considered to proceed both via a one-step pathway and via a two-step pathway. CO₂ was found to suppress the deactivation of the catalyst during the dehydrogenation of ethylbenzene. This revised version was published online in July 2006 with corrections to the Cover Date.     

煤在炼焦过程中热解脱硫降低焦炭中硫含量

通过模拟工业焦化过程,针对一种高硫煤考察了不同气体种类、流量及加热速率下,焦炉煤气返回焦化过程对物焦炭中硫含量变化的影响。结果表明,焦化过程中通入H2,CH4和N2气体可以抑制热解气中的硫返回固体焦炭中,H2达到的焦炭脱硫量最大,其次是CH4和N2;增大气体流量、减小加热速率有利于使硫向气相转移,从而使固体焦炭中的硫分配降低;固体焦炭中硫含量变化亦表明,H2效果较佳,在3．0,1．5℃／min2种加热速率下可使焦炭中硫含量分别降低0．36％～0．39％和0．46％～0．56％。     

Promotion of Fe3O4/Cr2O3 high temperature water gas shift catalyst

The promotion of Fe₃O₄/Cr₂O₃ high temperature water gas shift catalysts is described and discussed. Catalysts containing 2 wt% B, Cu, Ba, Pb, Hg and Ag are prepared by co-precipitation. B is found to poison the activity slightly whereas the other additives did increase the activity, with the relative order being Hg>Ag,Ba>Cu>Pb>unpromoted>B. The promoters decrease the activation energy of the catalyst, but the data give a linear relationship for the Constable–Cremer plot and it is concluded that CO adsorption is an important factor controlling activity.     

催化还原烟气中SO2到单质硫的研究进展

综述了烟气中催化还原SO₂到单质硫的研究进展，着重介绍了无氧及含氧体系下以H₂和CO为还原剂，将SO₂还原为单质硫的主要研究成果，主要包括各种催化剂的组成、性能和催化机理，并对催化还原脱硫的研发趋向作了展望。     

Core-shell Fe3O4@SiO2 nanoparticles synthesized with well-dispersed hydrophilic Fe3O4 seeds

Silica coated magnetite (Fe3O4@SiO2) core-shell nanoparticles (NPs) with controlled silica shell thicknesses were prepared by a modified St?ber method using 20 nm hydrophilic Fe3O4 NPs as seeds. The core-shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and UV-Vis adsorption spectra (UV-Vis). The results imply that NPs consist of a crystalline magnetite core and an amorphous silica shell. The silica shell thickness can be controlled from 12.5 nm to 45 nm by varying the experimental parameters. The reaction time, the ratio of TEOS/Fe3O4, and the concentration of hydrophilic Fe3O4 seeds were found to be very influential in the control of silica shell thickness. These well-dispersed core-shell Fe3O4@SiO2 NPs show superparamagnetic properties at room temperature.     

煤炭行业二氧化硫的危害及防治

阐述了二氧化硫的排放给环境带来的严重危害及我国二氧化硫排放的现状,论述了燃烧前、燃烧中和燃烧后三种脱硫方法的特点及应用范围,提出要加强二氧化硫的防治.     

氧化铁的制备及在可见光下的光催化性能研究

利用XRD、TEM对制备的氧化铁进行分析。以活性染料的水溶液为模拟废水，以可见光为光源，研究了催化剂用量、光照时间、催化剂结构及粒径大小、烧结温度等因素对废水降解的影响；利用红外、紫外等手段分析材料的光催化活性。