TiAl基羰基硫水解催化剂的中毒机制与抗氧性能研究

高炉煤气脱硫是实现钢铁行业多工序全流程超低排放的关键。高炉煤气中主要有机硫组分是羰基硫（COS）,常用γ-Al₂O₃基催化剂水解脱除,但是其抗氧性能有待提高。采用共沉淀法制备了Ti_0.5Al和K_0.2Ti_0.5Al催化剂,考察了催化剂在含氧气氛下的COS水解催化性能,并分析了氧体积分数对COS转化率和H₂S产率的影响规律。活性测试结果表明,Ti_0.5Al催化剂的初始COS转化率接近90%,随着反应时间增长效率逐渐降低至60%以下;K_0.2Ti_0.5Al催化剂在0.5% （体积分数） O₂的气氛下持续反应22 h后,其COS转化率仍可保持在93.44%。表征结果显示,催化剂失活后比表面积大幅减小,表面碱性显著减弱。此外,活性中心Al原子硫酸化是导致催化剂失活的主要原因,而硫酸盐的沉积为次要原因。原位红外结果表明,K的引入可显著减弱O₂在催化剂表面的吸附,并且阻断中间过渡物种的氧化,这是K提高催化剂抗氧性能的关键。     

γ-Al2O3基催化剂上高炉煤气COS的水解活性研究

高炉煤气脱硫是实现钢铁行业多工序全流程超低排放的关键。高炉煤气中主要含硫组分是羰基硫(COS),常用γ-Al₂O₃基催化剂水解脱除,但是其水解活性及抗氧能力有待提高。本工作采用浸渍法制备了添加Fe和La活性组分的催化剂,通过ICP,XRD和TPD等手段表征了催化剂的理化性质,并在固定床-气相色谱联用装置考察了空速、粒径对催化剂催化水解COS过程的扩散效应,研究了催化剂的理化性质与COS水解活性的构效关系以及O₂的作用机制。结果表明,催化剂在80℃,160 000h^-1条件下,活性组分Fe和La的添加可明显提高γ-Al₂O₃基催化剂的碱性位点;同时,丰富的孔隙结构降低了内扩散阻力,增强了H₂S从催化剂表面到气相的传质。Fe/Al₂O₃催化剂在保持较高的水解活性的同时能够协同脱除H₂S,但是O₂的存在增强了H₂S的吸附及其与Fe的...     

高炉煤气特征组分分析及其对脱硫过程的影响研究进展

高炉煤气（BFG）作为炼铁过程中副产的可燃气体,具有明显的资源回收价值,但其同时存在热值低、成分复杂等问题。目前大多数研究集中在对羰基硫（COS）、硫化氢（H₂S）等有害成分的脱除,而鲜有对高炉煤气特征组分的研究或报道。研究者对高炉煤气特征组分的来源、生成路径等不明朗,导致在研究过程中忽略了煤气复杂组分的相互影响,很多技术在工业应用时问题频发。本文阐述并分析了高炉煤气特征组分的来源及生成路径,进而讨论了高炉煤气特征组分对脱硫过程的影响。高炉原料、燃料和空气在高温条件下经过复杂的化学反应,生成粉尘、N₂、O₂、CO、CO₂、H₂、CH₄、H₂O、HCl、HCN、硫化物等共同组成高炉荒煤气,荒煤气中的O₂、CO_x、H₂、H₂O、HCl、硫化物等化学成分对COS转化或H₂S脱除过程产生影响,导致催化剂中毒或转化率下降。本文通过分析探讨特征组分在高炉煤气产生和脱硫净化过程中的相互作用及影响规律,为超低排放背景下高炉煤气的净化和资源化提供方向和参考。     

CeO2基水煤气变换催化剂COS中毒热力学研究

为探究COS对Ce O₂基水煤气变换催化剂的中毒机制，用HSC Chemistry 6.0热力学数据库对Ce O₂变换催化剂的COS中毒热力学进行了模拟计算，从热力学角度分析了在100～450℃水气变换温度下，COS分别与CO、H₂O和O₂共存时，Ce O₂催化剂可能发生的反应及产物。结果表明，温度分别高于150℃和300℃时，H₂O-COS-Ce O₂和CO-COS-Ce O₂体系中的Ce O₂硫中毒可被明显抑制；O₂对Ce O₂硫中毒的影响最大，整个催化温度范围内，O₂-COS-Ce O₂体系中所有反应均可自发进行，含S固态产物为Ce₂(SO₄)₃、Ce S₂和S。     

T907型水解催化剂用于不同原料COS水解的性能与应用

本文介绍了T907型COS水解催化剂在高CO₂煤气、一氧化碳、二氧化碳和液相丙烯中COS水解的研究和应用。试验及工业应用表明，T907型催化剂是一种适用于各种气液进料、具有高水解转化率和抗氧毒性能的优良催化剂。在气固催化反应中，其最佳使用温区为100~120℃；在气液相催化反应中，其最佳使用温区为15~40℃。     

镓铝固溶体的制备及其COS催化水解性能

工业生产中含硫废气的排放严重污染了大气环境并且危害人体健康，COS的水解脱除是处理含硫废气的有效手段之一。通过水热法合成GaAl(O)催化剂，并且通过XRD、SEM、BET、XPS等技术对其进行系统的表征，结果表明，Ga离子进入了Al₂O₃晶格内部，催化剂的表面具有碱性。性能测试结果表明，Ga的添加能够极大程度地提升催化剂的水解性能。考察反应温度、空速和水含量对COS催化水解性能的影响，在140℃之后，GaAl(O)催化剂的COS转化率和H₂S选择性都约保持100%,并且适当的水含量有助于COS转化率的提升，在低于180℃时，COS转化率在高空速下相对较低。在模拟工业生产的反应条件下考察催化剂的稳定性，GaAl(O)催化剂在24 h的测试中保持100%的COS转化率。     

LaMnO3/生物炭催化剂低温NH3-SCR催化脱硝性能研究

以La-Mn钙钛矿氧化物为活性组分,生物炭为载体,利用浸渍法制备负载型脱硝催化剂LMO/BCNA。利用固定床反应装置考察了催化剂的催化活性以及耐硫耐水性能,100～250℃范围内,NO转化率>80%,N₂选择性>90%,225℃时NO转化率最高,为95.8%,对应的N₂选择性为95.4%。与氧化物相比,负载型催化剂的催化活性大幅提升,同时也扩宽了工作温度区间;生物炭载体的引入,减弱了催化剂对H₂O、SO₂的吸附,增强了耐硫耐水性能。应用稳态动力学方法构建催化反应动力学模型,在实验条件范围且O₂含量为5%时,催化NH₃-SCR反应过程中NO、O₂、NH₃的反应级数分别为0.66、0、0,并得到LMO/BCNA催化的反应活化能为25.52 k J/mol,低于商用钒钨钛催化剂的化学反应活化能(40～94 k J/mol)。     

K2CO3对兰炭催化气化特性的影响

在固定床中考察了不同K₂CO₃植入浓度和不同温度条件下兰炭催化气化特性。结果表明，5%的催化剂植入浓度主要起到填充孔隙的作用，当植入浓度增加到10%以后，催化剂发生堆积会使颗粒表面及内部形成较多孔隙。提高气化温度可提高兰炭转化率，超过750℃之后碳转化率增幅减缓，催化剂饱和装载浓度为10%。在颗粒表面和开放孔隙中的高浓度C(O)才具有较高的脱附速率，并提高CO生成速率。在非催化条件下，随着气化的进行CO/CO₂下降，而H₂/(2CO₂+CO)先增后减。在催化条件下，H₂/(2CO₂+CO)稳定在1.5～1.7。催化剂兰炭样品中出现了K₂Ca(CO₃)₂双金属碳酸盐、K₂O、KO₂等活性组分，并随催化剂植入浓度的增加而增加。催化剂植入浓度的增加会导致失活现象加重，但兰炭在750℃条件下气化1 h 催化剂没有完全失活。     

高压高水气比有机硫转化工艺及QDSJ-04有机硫水解剂的开发与应用

针对传统有机硫水解催化剂在高水气比工艺条件下相变并失活的不足,开发了高压高水气比有机硫转化工艺和QDSJ-04有机硫水解剂。介绍了新工艺的流程、特点,分析了QDSJ-04有机硫水解剂的耐高空速性能、强度、抗水合性能及其在神华宁煤400万t/a煤制油变换装置的工业应用情况,结果表明:开发的高压高水气比有机硫转化工艺具有避免传统工艺"冷热病",设备投资少等特点,节能效益显著;开发的QDSJ-04有机硫水解剂,在空速6 000 h-1以上和水气比0.6～0.7条件下使用时,催化剂不水合、不相变,床层压差稳定且小于0.5 MPa,COS转化率大于80%,可满足高压、高水气比和高CO含量合成气条件对水解催化剂有机硫转化性能的要求。     

SO2对稀土精矿催化剂NH3-SCR脱硝催化性能的影响

抗硫性能是评价脱硝过程中催化剂性能的关键指标,研究SO₂对催化剂理化特性的影响对催化剂脱硝应用具有重要意义。通过焙烧处理白云鄂博稀土精矿得到稀土精矿催化剂,利用催化剂抗硫性能实验台,结合SEM、BET、XRD和FT-IR,分析了O₂、NH₃、NO气氛下SO₂在催化剂表面的吸附及不同SO₂浓度对催化剂催化脱硝性能的影响。结果表明, SO₂对稀土精矿催化剂脱硝性能有显著的促进作用,300℃时,NO转化率从28%提高至50%,350℃时,NO转化率从42%提高至75%; SEM、BET和XRD结果表明催化剂抗硫性能测试前后的物理结构和化学组成基本保持不变,稀土精矿催化剂具有较好的抗硫性能;FT-IR结果证实SO₂的吸附使稀土精矿催化剂表面B酸性位点增多,催化剂对NH₃的吸附能力增强,因此有利于提高催化剂活性。研究结果可为白云鄂博稀土精矿催化剂NH₃-SCR脱硝应用过程中抗硫性能提供有价值的基础数据参考。     

Selective oxidation of propylene to acrolein over supported V2O5/Nb2O5 catalysts: An in situ Raman, IR, TPSR and kinetic study

The vapor-phase selective oxidation of propylene (H₂CCHCH₃) to acrolein (H₂CCHCHO) was investigated over supported V₂O₅/Nb₂O₅ catalysts. The catalysts were synthesized by incipient wetness impregnation of V-isopropoxide/isopropanol solutions and calcination at 450 °C. The catalytic active vanadia component was shown by in situ Raman spectroscopy to be 100% dispersed as surface VO_x species on the Nb₂O₅ support in the sub-monolayer region (<8.4 V/nm²). Surface allyl species (H₂CCHCH_2*) were observed with in situ FT-IR to be the most abundant reaction intermediates. The acrolein formation kinetics and selectivity were strongly dependent on the surface VO_x coverage. Two surface VO_x sites were found to participate in the selective oxidation of propylene to acrolein. The reaction kinetics followed a Langmuir–Hinshelwood mechanism with first-order in propylene and half-order in O₂ partial pressures. C₃H₆-TPSR spectroscopy studies also revealed that the lattice oxygen from the catalyst was not capable of selectively oxidizing propylene to acrolein and that the presence of gas phase molecular O₂ was critical for maintaining the surface VO_x species in the fully oxidized state. The catalytic active site for this selective oxidation reaction involves the bridging VONb support bond.     

Reduction of carbon dioxide with water under concentrated sunlight using photocatalyst combined with Fe-based catalyst

The reduction of CO₂ with water into valuable organic compounds under concentrated sunlight was investigated for the first time over a hybrid catalyst, in which a Pt-loaded K₂Ti₆O₁₃ photocatalyst was combined with a Fe-based catalyst supported on a dealuminated Y-type zeolite (Fe-Cu-K/DAY). In this reaction system, the Pt/K₂Ti₆O₁₃ catalyst decomposes water to produce H₂ and the Fe-Cu-K/DAY catalyst reduces CO₂ with the resulting H₂ into organic compounds. When only the Pt/K₂Ti₆O₁₃ photocatalyst was used, organic compounds such as CH₄, HCOOH, and HCHO were formed together with H₂, indicating that CO₂ can also be directly reduced over Pt/K₂Ti₆O₁₃. On the contrary, when the hybrid catalyst was used, CH₃OH and C₂H₅OH were produced in addition to the above products, depending on the reaction temperature and catalyst composition. The reaction temperature significantly increased by concentrating the solar irradiation, reaching 600 K and increasing the product yields. It is suggested that such a high reaction temperature facilitates both the photoreduction and hydrogenation of CO₂ over Pt/K₂Ti₆O₁₃ and Fe-Cu-K/DAY, respectively.     

Partial oxidation of methane to synthesis gas over Co/Ca/Al2O3 catalysts

A series of calcium-modified alumina-supported cobalt catalysts were prepared with a two-step impregnation method, and the effect of calcium on the catalytic performances of the catalysts for the partial oxidation of methane to syngas (CO and H₂) was investigated at 750 °C. Also, the catalysts were characterized by XRD, TEM, TPR and (in situ) Raman. At 6 wt.% of cobalt loading, the unmodified alumina-supported cobalt catalyst showed a very low activity and a rapid deactivation, while the calcium-modified catalyst presented a good performance for this process with the CH₄ conversion of 88%, CO selectivity of 94% and undetectable carbon deposition during a long-time running. Characterization results showed that the calcium modification can effectively increase the dispersion and reducibility of Co₃O₄, decrease the Co metal particle size, and suppress the reoxidation of cobalt as well as the phase transformation to form CoAl₂O₄ spinel phases under the reaction conditions. These could be related to the excellent catalytic performances of Co/Ca/Al₂O₃ catalysts.     

Partial oxidation and combined reforming of methane on Ce-promoted catalysts

Pt/ZrO₂ and Pt/Ce_0.14Zr_0.86O₂ catalysts containing 0.5 and 1.5 wt.% Pt were studied in order to evaluate the effect of the support reducibility and metal dispersion on the catalyst stability for the partial oxidation and the combined partial oxidation and CO₂ reforming of methane. The Pt/Ce_0.14Zr_0.86O₂ catalysts proved to be more active, stable and selective than Pt/ZrO₂ catalysts during the partial oxidation reaction. No increase in deactivation was observed when the CH₄:O₂ feed ratio was increased from 2:1 to 4:1. In addition, no water formation was observed at the high CH₄:O₂ ratios. The activity of the catalyst is dependent upon both the dispersion and the ability of the catalyst to resist carbon deposition.

The addition of CO₂ resulted in a decrease in the methane conversion and a decrease in the H₂/CO ratio for the Ce_0.14Zr_0.86O₂ and ZrO₂ supported catalysts. Small increases in the temperature of the bed have been recorded during the partial oxidation reaction. However, within a few minutes the temperature stabilizes below the furnace temperature providing indirect evidence for the combined combustion and reforming mechanisms previously proposed. The 1.5 wt.% Pt/CeZrO₂ catalyst shows promise for the autothermal reforming reaction based on the stability during transient operation.     

In situ IR and pulse reaction studies on the active oxygen species over SrF2/Nd2O3 catalyst for oxidative coupling of methane

Pulse reaction method and in situ IR spectroscopy were used to characterize the active oxygen species for oxidative coupling of methane (OCM) over SrF₂/Nd₂O₃ catalyst. It was found that OCM activity of the catalyst was very low in the absence of gas phase oxygen, which indicated that lattice oxygen species contributed little to the yield of C₂ hydrocarbons. IR band of superoxide species (O₂⁻) was detected on the O₂-preadsorbed SrF₂/Nd₂O₃. The substitution of ¹⁸O₂ isotope for ¹⁶O₂ caused the IR band of O₂⁻ at 1128 cm⁻¹ to shift to lower wavenumbers (1094 and 1062 cm⁻¹), consistent with the assignment of the spectra to the O₂⁻ species. A good correlation between the rate of disappearance of surface O₂⁻ and the rate of formation of gas phase C₂H₄ was observed upon interaction of CH₄ with O₂-preadsorbed catalyst at 700 °C. The O₂⁻ species was also observed on the catalyst under working condition. These results suggest that O₂⁻ species is the active oxygen species for OCM reaction on SrF₂/Nd₂O₃ catalyst.     

非热等离子体催化转化C1分子及其催化剂研究进展

非热等离子体催化具有反应条件温和、启动快和反应器结构紧凑等特点,在C₁分子催化转化领域（如CO₂加氢、甲烷活化、水煤气变换反应和甲醇重整制氢）有着广阔的应用前景。具体来说,等离子体特有的高能电子可在气相中快速活化稳定性极强的C₁分子并生成活性物质,接着与催化剂结合发生表面化学反应,从而实现常温常压下C₁分子的高效转化。然而,等离子体与催化剂之间的协同作用机制以及催化机理极为复杂,仍有待进一步研究。本综述简单介绍了非热等离子体催化转化C₁分子的近期研究进展,重点探讨了适用于非热等离子 体的催化剂研究以及催化机理的高级原位表征。最后,提出了非热等离子体催化转化C₁分子的未来发展方向：①设计并构筑适用于非热等离子体催化的高效催化剂,并研究其构效关系;②发展高级原位表征技术,揭示活性物质的作用机理以及催化机理;③设计并构建高效的等离子体催化反应器,并建立反应器的理论模型和数值模拟方法,科学指导等离子体反应器的设计、优化和放大。     

Investigations of sulphur deactivation of NOx storage catalysts: influence of sulphur carrier and exposure conditions

The influence of SO₂, H₂S and COS in low concentrations on the deactivation of Pt/Rh/BaO/Al₂O₃ NO_x storage catalysts was investigated. Different samples of the catalyst were exposed to synthetic gas mixtures mimicking lean/rich engine cycling in a mixed lean application at 400 °C. The lean gas mixture contained 8 vol.% O₂, 500 vol-ppm C₃H₆ and 400 vol-ppm NO balanced to 100 vol.% with Ar. The rich excursions were performed by switching off the oxygen supply. Sulphur, 25 vol-ppm of either SO₂, H₂S or COS, was added to the gas flow either during the lean, the rich or both periods. This procedure aimed at investigating the influence of the exposure conditions and therefore the lean and rich periods were kept equally long (5 min). In addition, thermodynamical calculations for the prevailing conditions were performed.

It was concluded that all sulphur compounds investigated, i.e. SO₂, H₂S and COS, had similar, negative impact on the NO_x storage ability of the catalyst and that they all showed increased deactivation rates during rich exposure compared to lean. During lean exposure, all sulphur carriers showed similar behaviour, while H₂S and COS caused severe loss of noble metal activity during rich exposure.     

一步水热法制备电解水析氧反应Ni3S2@Mo2S3高效催化剂

采用一步水热法,由泡沫钼镍合金同时提供钼源和镍源在泡沫钼镍合金表面原位制备了Ni₃S₂@Mo₂S₃,并将其直接作为自支撑电极用于催化碱性介质中的电解水析氧反应（OER）。利用多种表征测试技术研究了样品的形貌、组成、OER电催化性能,结果显示：Ni₃S₂@Mo₂S₃呈纳米板形貌,由六方Ni₃S₂和单斜Mo₂S₃按5∶1的比例复合而成;在1 mol·L^-1 KOH 溶液中,Ni₃S₂@Mo₂S₃催化剂仅需要170 mV过电位就可达到10 mA·cm^-2电流密度（欧姆补偿后）,且在50 h的稳定性测试期间性能基本无衰减,优于贵金属催化剂IrO₂以及文献报道的Ni-Mo基复合催化剂。Ni₃S₂@Mo₂S₃具有优异电催化性能的原因可归于不同过渡金属化合物的协同作用、原位生长自支撑、电化学活性面积大以及液下疏气性等因素。