共沉淀法制备钛锆复合载体及其在加氢脱硫催化剂中的应用

 共沉淀法制备了n(TiO2):n(ZrO2)=4:1,3:2,1:1,2:3,1:4及单一TiO2、ZrO2氧化物,并用浸渍法制备了10% MoO3/TiO2-ZrO2,10% MoO3/TiO2,10% MoO3/ZrO2催化剂。用X射线衍射、N2吸附方法对催化剂进行表征,在间歇式高压反应釜上进行活性评价。结果表明,550 ℃煅烧2 h后,TiO2-ZrO2(1:1),TiO2-ZrO2(2:3),TiO2-ZrO2(3:2)为无定型,其余载体出现不同程度的结晶。复合氧化物的比表面积均大于单一氧化物,其中TiO2-ZrO2(1:1)的比表面积最大（191.2 m2/g）。噻吩的加氢脱硫反应作为模型反应来评价催化剂的活性。催化剂的活性随着ZrO2在复合载体中含量的增加而提高,10% MoO3/TiO2-ZrO2(1:1)的活性最高。当ZrO2含量进一步增加时,催化剂的活性降低,单一ZrO2载体催化剂的活性最低。     

Dibenzothiophene Hydrodesulfurization Activity of MoS2 Supported in Sol–Gel ZrO2–TiO2 Mixed Oxides

Abstract

In this work, we report the effect of support composition on the properties of MoS₂ impregnated in sol–gel ZrO₂–TiO₂ mixed oxides as dibenzothiophene hydrodesulfurization catalyst. The supports calcined at 500°C were characterized by N₂ physisorption and X-ray diffraction (electronic radial distribution function). The oxidic impregnated materials (2.8 Mo atoms/nm²) were sulfided at 400°C under a H₂S/H₂ stream. The sample impregnated on the equimolar support showed the highest activity per mass of catalysts whereas the one with TiO₂ carrier was superior in a per mass of Mo basis. Marked differences in products selectivity were observed by TiO₂ addition in the supports. The hydrodesulfurization route to partially hydrogenated compounds was favored over the mixed oxides-supported catalysts meanwhile the direct desulfurization (to biphenyl) was promoted on the ZrO₂-supported solid. It is suggested that among other properties the dispersion and morphology of the MoS₂ phase could influence that behavior.     

含介孔ZSM-5分子筛的柴油加氢脱硫催化剂的性能研究

以添加不同量的介孔ZSM-5分子筛的Al2O3为载体,MoO3-CoO为金属活性组分,考察了介孔ZSM-5分子筛的含量对柴油加氢脱硫活性的影响。采用直馏柴油评价催化剂的加氢脱硫活性。结果表明,随着介孔分子筛ZSM-5含量的增加,催化剂的加氢脱硫活性先增加后降低,介孔分子筛ZSM5加入量为12%的催化剂C12-ZSM5活性最高,比对比剂C0-ZSM5和C12-普-ZSM5的活性高,说明向载体中添加介孔ZSM-5分子筛能够有效地提高催化剂的加氢脱硫活性。     

Co-Mo/meso-A12O3蜡油加氢处理催化剂的制备

以Pluronic P123作结构导向剂,通过酸碱中和法制备氧化铝作载体,分别采用共浸渍法及分步浸渍法制备Co-Mo型蜡油加氢处理催化剂,其中MoO3的负载量为20.0% (w),CoO的负载量为7.81% (w)。样品的表征分析结果表明,与商用氧化铝相比,自制氧化铝具有部分有序的介孔结构、较高的比表面积及孔体积、较大的孔径及较高的结晶度;与分步浸渍法相比,共浸渍法制备的催化剂具有更大的比表面积以及更多的酸性位,且这两种催化剂中的活性组分都均匀地分散在载体上。在实验室固定床微反上对催化剂进行加氢处理性能评价,实验结果表明,以自制氧化铝为载体、采用共浸渍法制备的催化剂具有良好的加氢脱硫及脱氮活性。在反应温度380 ℃、反应压力15 MPa、体积空速0.6 h-1、氢油体积比1000:1的条件下,催化剂的加氢脱硫率可达到99.75%,加氢脱氮率为99.86%,产品中的S含量为9.4 μg/g,N含量为1.1 μg/g,满足后续工艺的要求。     

MoO_3/TiO_2-SiO_2催化剂的阈值效应

采用气相流动吸附法制备TiO2 /SiO2 复合载体 ,浸渍法担载一定量MoO3。用XRD、LRS和TPR等考察了MoO3在TiO2 /SiO2 表面的分散状态 ,中压固定床反应装置测定MoO3/TiO2 SiO2 、MoO3/SiO2 催化剂的噻吩加氢脱硫(HDS)、环己烯加氢 (HYD)和苯加氢 (BHD)活性。结果表明 ,(1 )TiO2 的加入有利于加强MoO3与载体之间的相互作用 ,促进MoO3在载体表面的分散 ,提高其分散阈值 ;(2 )当MoO3载量低于分散阈值时 ,其HDS、HYD和BHD活性随MoO3载量的增加而明显增大 ,但在高于分散阈值后 ,几乎保持不变 ,能明显体现负载型Mo催化剂在HDS、HYD和BHD反应中的阈值效应 ;(3 )MoO3 TiO2 /SiO2 催化剂的HDS、HYD和BHD活性都较MoO3/siO2 催化剂高 ,TiO2 能很大程度地改善MoO3/SiO2 催化剂的HDS、HYD活性。     

二硫化钼催化剂的制备与应用

综述了二硫化钼催化剂的物理化学性质以及国内外的几种制备方法,包括工业天然法和化学合成法。简要介绍了载体对催化剂的一些影响;从加氢脱硫、加氢脱氧及催化加氢几个方面对二硫化钼催化剂的应用进行了论述;对二硫化钼的形态,嵌入不同金属的MoS2催化剂在应用中对反应的影响及催化加氢机理进行了简要叙述。     

高密度泥浆法处理重金属酸性废水连续试验研究

采用高密度泥浆法(HDS)处理某冶炼厂酸性重金属废水,在底泥回流比15∶1左右,中和反应pH值10左右,PAM用量4 mL/L,出水水质达到国家一级排放标准。试验发现浓密机结构是决定底流浓度的关键因素之一,通过对浓密机结构优化改造,最终稳定获得了底流浓度大于25%的中和渣,大大降低了中和渣的体积量并改善了污泥的过滤性能。     

Effect of sintering on the catalytic functionalities of MOS2/Al2O3 catalysts

Effect of sintering on physico-chemical and catalytic properties of Mo, Co-Mo, Ni-Mosupported on -Al₂O₃ is reported. Such effects on hydrodesulfurization (HDS), hydrogenation (HYD) and hydrodeoxygenation (HDO) are investigated as a function of sintering temperature. The results indicated that HDS and HYD have different optimum calcination temperatures and these functionalities originate from different sites. The results are discussed in the light of molybdenum sulfide dispersion, promotional effects and phase transformations of active component, promoters and support.     

An EXAFS study of the Mo/TiO2 hydrodesulphurization catalysis

In-situ EXAFS studies of sulphided Mo/TiO₂ catalysts have shown that at low Mo loadings (2–4 wt%), an active species with a short Mo-S distance of 2.25 Å is formed, while on Mo/TiO₂ with high Mo loadings as well as on Mo/-Al₂O₃, bulk MoS₂ (Mo-S, 2.42 Å) is formed. The species with the short Mo-S distance has Mo in an oxidation state close to 6 + and is likely to result from the sulphidation of the tetrahedral molybdate species present in the oxidic precursor at low Mo loadings. The calcination temperature of the oxidic precursor appears crucial, a high calcination temperature of 973 K favouring the formation of MoS₃ on sulphidation, and a low calcination temperature of 623 K favouring MoS₂.Contribution No. 790 from the Solid State and Structural Chemistry Unit.     

New approach to unsupported ReS2 nanorod catalyst for upgrading of heavy crude oil using methane as hydrogen source

Highly active ReS₂ nanocatalysts were prepared by CVD method and characterized by XRD, BET -BJH, Raman spectroscopy, XPS, TPR, NH₃-TPD, SEM, and HRTEM techniques. Catalytic activities were used in upgrading heavy crude oil using methane as hydrogen source. The results showed a significant increase in API and decrease in sulfur and nitrogen content of crude oil. RSM technique was used to investigate the interactive effects of temperature (200–400 °C), pressure (20–40 bar) and dosage of nanocatalyst (0.5–2 wt. %) on the performance of HDS reaction. The results represent that the maximum predicted HDS activity (74.375%) was estimated under the optimal conditions (400 °C, 20 bars, and 2 wt % of nanocatalyst). Also, the effect of reaction temperature, pressure and dosage of ReS₂ nanorods catalyst on HDN of heavy crude oil was investigated and highest efficiency in the HDN process (93%) occurred at 400 °C and 40 bar using 2 wt % ReS₂.