Ti对Ni2P催化剂喹啉加氢脱氮性能的影响

本文以喹啉为模型化合物,考察了钛的不同引入量对Ni2P催化剂加氢脱氮（HDN）性能影响,通过表征发现少量钛的引入影响了Ni2P前体的还原性能。同时,钛的引入也提高了Ni2P催化剂的加氢脱氮性能.随着钛引入量的增加,加氢脱氮活性出现先增加后降低的趋势,当Ti/Ni摩尔比为0.02时,Ti0.03Ni₂P表现出最高的加氢脱氮活性。     

活性金属Ni d电荷密度对Ni2P/Al2O3催化剂菲加氢性能的影响

高温煤焦油中菲含量高,将菲深度加氢饱和得到全氢菲,可提升菲利用率,且全氢菲密度大,热值高,可作为喷气燃料理想组分。然而,在菲加氢反应过程中菲与中间加氢产物的竞争吸附不利于菲在催化剂上吸附活化,且对称八氢菲进一步加氢是菲加氢饱和过程的速控步骤,其吸附活化困难不易解决,催化剂活性难以满足加氢需求。根据稠环芳烃与过渡金属间π络合吸附机理,在反应物吸附活化过程中,稠环芳烃分子和活性金属分别充当电子供体和电子受体,故Ni基催化剂中活性金属Ni处于缺电子状态时利于生成全氢菲,但关于Ni缺电子量及其电子结构如何影响催化剂菲、对称八氢菲加氢性能的原因需进一步探究。此外,基于负载型Ni₂P催化剂稳定性高、耐硫、耐氮性强等优势,采用次磷酸盐歧化法通过调变P/Ni物质的量比制备具有不同Ni d电荷密度的Ni₂P/Al₂O₃催化剂,考察Ni d电荷密度对菲、对称八氢菲吸附和反应性能的影响规律。结果表明,在320℃、5 MPa、空速1 309 h^-1反应条件下,Ni-2.5P/Al₂     

Ni2P催化剂的制备及加氢脱硫性能研究

通过共沉淀并用原位程序升温还原的方法制备了体相Ni2P催化剂,用二苯并噻吩(DBT)作为模型化合物进行加氢脱硫(HDS)活性评价,结果显示Ni2P具有比较低的加氢活性和相对高的脱硫活性,且有很高的稳定性。     

乙二醇对NiMoP/Al2O3催化剂上喹啉加氢脱氮反应的影响

燃料油中的含氮化合物是空气中NOx的主要来源,为了降低NOx排放,满足日益严格的排放标准,需要降低燃料油中含氮化合物含量,开发研制高效的加氢精制催化剂是达到这一目标的有效手段。通过在NiMoP浸渍液中添加不同含量乙二醇,制备一系列NiMoP/Al₂O₃催化剂,以喹啉为模型化合物,对催化剂进行加氢脱氮活性评价,分析表征各类脱氮产物。结果表明,乙二醇的加入能够大幅提高喹啉脱氮率,尤其是喹啉全加氢产物中C-N键的直接断键能力得到较大提高。     

WP/γ-Al2O3催化剂的制备、表征及加氢脱硫和加氢脱氮活性

Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%-37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA, XPS and 31p MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W species was in a high valence state W6 on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31p MAS-NMR results indicated that 31p shift from 85% H3PO4 of 2.55 × 10-4 for WP and 2.57 × 10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activities and lower HDS activities than those prepared by the impregnation method under the same loading of WP.WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.     

一维TiO2-Al2O3载体的制备及其在加氢脱氮中的应用

为提高现有负载型NiMoS催化剂的加氢活性,以碳纳米管为结构导向剂,分别采用浸渍法和溶胶-凝胶法制备了2种一维TiO₂-Al₂O₃载体,并采用共浸渍法制备了相应的负载型NiMoS催化剂,探究了不同结构的载体对NiMoS/TiO₂-Al₂O₃催化剂加氢脱氮性能的影响。结果表明,当选择以溶胶-凝胶法制备的一维TiO₂-Al₂O₃为载体时,NiMoS/TiO₂-Al₂O₃催化剂上的加氢脱氮活性较高,在350℃、氢压为3 MPa、转速为400 r/min的条件下反应4 h,喹啉的转化率达到99%以上,脱氮率达到40.75%。     

Fe2O3/Ni2O3/Al2O3催化剂制备及其催化氧化靛蓝废水研究

以三氧化二铝为载体,采用浸渍沉淀法制备系列Fe2O3/Ni2O3/Al2O3催化剂。采用TG-DTA,XRD及ESEM等技术对催化剂进行表征,确定催化剂的最佳焙烧温度为460℃。以次氯酸钠为氧化剂,同时考察m(三氧化二镍)/m(三氧化二铝)、m(三氧化二铁)/m(三氧化二镍)、m(次氯酸钠)∶m(靛蓝废水)、pH对印染靛蓝废水处理的影响。结果表明:m(三氧化二镍)/m(三氧化二铝)=0.3,m(三氧化二铁)/m(三氧化二镍)=0.04,m(次氯酸钠)∶m(靛蓝废水)=1∶11,pH=7,反应温度为20℃,常压反应时间为2 h时,COD的去除率为95.3%。     

Al2O3-3Al2O3·2SiO2-ZrO2耐火材料的相组成

Al2O3-SiO2-ZrO2系耐火材料应用范围广,特别被用作陶瓷辊,具有力学强度高、抗热震性能优良、耐碱类化合物侵蚀和高温蠕变率低的特性。Al2O3-SiO2-ZrO2系耐火材料性能很大程度上取决于其结晶相和玻璃相的总量和化学成分,采用定量XRPD和XRF研究了原料中Al2O3/SiO2比和氧化铝颗粒尺寸分布对结晶相和玻璃相的总量及其化学成分的影响。耐火材料由莫来石、刚玉、ZrO2的多晶体和总量各异的玻璃相组成。莫来石含量及其晶胞参数和成分随烧成温度改变,但主要受原料中Al2O3/SiO2比的影响。     

Cs2O/Al2O3-ZrO2催化剂的制备及催化性能研究

本文采用醇盐-凝胶溶胶法制备Al2O3-ZrO2催化剂复合载体,并通过超声浸渍法制备Cs2O/Al2O3-ZrO2催化剂。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱(EDS)等技术考察了复合载体对催化剂的晶相结构、表面形貌的影响;并以甲醛和醋酸甲酯合成丙烯酸甲酯反应为探针,讨论了单一载体及铝锆比不同的复合载体催化剂的催化活性。实验结果表明:经过500℃煅烧的催化剂具有良好的晶形;材料具有蜂窝状孔道,具有良好的通透性;Cs的负载量为4.42%;当mAl2O3∶mZrO2=1∶0.25时,所得催化剂的活性最高,收率达到14.76%。     

Al2O3负载Cu基催化剂的制备及其催化乙炔选择性加氢性能

采用等体积浸渍法合成了Cu(OH)₂/Al₂O₃前体，经乙炔处理、氢气还原制备了Al₂O₃负载的Cu基催化剂。采用X射线衍射(XRD)、透射电镜(TEM)和N₂物理吸附对催化剂前体以及催化剂进行了表征，并在固定床反应器中系统考察了氢氧化铜负载量、乙炔处理温度、乙炔处理时间以及氢气还原温度对所制备催化剂催化乙炔选择性加氢性能的影响。研究结果表明：当Cu(OH)₂负载量为30%(质量分数)，乙炔处理温度为140℃，乙炔处理时间为2 h，氢气还原温度为150℃时，催化剂具有较高的低温乙炔选择性加氢活性。当反应温度为115℃时，乙炔转化率为98.50%，乙烯的选择性为66.15%，乙烷的选择性为15.75%,C₄的选择性为18.10%。     

Study on the hydrodesulfurization and the hydrodenitrogenation over Al2Oa-ZrO2 supported Ni2P catalysts

采用浸渍-沉淀法制备Al2O3-ZrO2复合氧化物,通过程序升温还原法制备Ni2P/Al2O3-ZrO2催化剂。运用X射线衍射、N2吸附-脱附、X射线光电子能谱技术对载体和催化剂进行表征,并以噻吩加氢脱硫、吡啶加氢脱氮反应为探针考察复合氧化物对Ni2P催化剂加氢活性的影响。结果表明,在Al2O3表面引入少量ZrO2,既保持了γ-Al2O3大比表面积的结构优势,又减少了P或Ni与Al2O3表面的接触,促进Ni2P的形成。载体中ZrO2质量分数20%的Ni2P/Al2O3-ZrO2催化剂活性最高,载体焙烧温度过高会导致催化剂活性下降。     

Characterization of Al2O3-ZrO2 mixed oxide catalytic supports prepared by the sol-gel method

A series of Al₂O₃-ZrO₂ mixed oxides was prepared by the sol-gel method with variable amounts of ZrO₂ between pure alumina and pure zirconia. Textural, bulk and surface characterization of the samples was carried out by nitrogen physisorption (S_BET, porosity), surface acidity, zero point charge (ZPC), thermal analysis (DSC, TGA), X-ray diffraction (XRD) and FT-Raman spectroscopy. The textural results show that at low zirconia contents, higher surface areas than those of pure alumina are obtained, and that the mixed oxides samples show a bimodal pore size distribution different from that of a mechanical mixture of the pure oxides. Also, in the zirconia-rich samples, higher surface areas than for pure zirconia are stabilized. The ZPC results indicate the formation of a surface composition equivalent to the bulk composition of the two oxides. The acidity measurements show that, as the density of acid sites in the mixed oxides increases steadily with zirconia content, a sharp increase is observed between the zirconia-rich mixed oxides and the pure ZrO₂. It appears possible then to tune the acidity of the mixed oxide by changing its composition. The XRD and FT-Raman results show that the incorporation of alumina in the support stabilizes the metastable cubic and tetragonal zirconia phases, possibly by a matrix effect which constrains the size of the ZrO₂ particles below the critical size beyond which the crystallization and transformation process to a more stable zirconia phase occurs.     

乙二胺四乙酸对NiMo/Al_2O_3催化剂加氢脱氮性能的影响

以氧化铝为载体,Ni和Mo为金属活性组分,添加不同含量乙二胺四乙酸,采用等体积浸渍法制备系列Ni Mo(x)/Al_2O_3(x为乙二胺四乙酸与Ni物质的量比)重质油加氢处理催化剂,考察乙二胺四乙酸加入量对催化剂加氢脱氮性能的影响,并采用N_2物理吸附-脱附、XRD和HRTEM等对催化剂进行表征。结果表明,乙二胺四乙酸的加入增强了金属组分与氧化铝载体间的相互作用,降低了MoS_2活性相的堆垛层数和片层长度,促进了活性相的分散。乙二胺四乙酸与Ni物质的量比为0.5时,MoS_2活性相堆垛层数和片层长度达到良好的结合,对应的催化剂Ni Mo(0.5)/Al_2O_3具有最优的加氢脱氮性能。     

CO oxidation catalysts based on copper and manganese or cobalt oxides supported on MgF2 and Al2O3

The catalytic activity of a mixed phase of copper–cobalt and copper–manganese oxides supported on magnesium fluorine or alumina has been studied in low temperature CO oxidation at 30 °C. During calcination, the oxides studied partially react to form different type spinels depending on the calcination temperature. These spinels have different effect on the catalytic activity. In low temperature CO oxidation the copper–manganese catalysts are more active than the copper–cobalt ones.     

Carbon formation and its influence on ethanol steam reforming over Ni/Al2O3 catalysts

Ethanol steam reforming was studied over Ni/Al₂O₃ catalysts. The effect of support (- and γ-Al₂O₃), metal loading and a comparison between conventional H₂ reduction with an activation method employing a CH₄/O₂ mixture was investigated. The properties of catalysts were studied by N₂ physisorption, X-ray diffraction (XRD) and temperature programmed reduction (TPR). After activity tests, the catalysts were analyzed by scanning electron microscopy (SEM) and thermogravimetric analysis (TG/DTA). Ni supported on γ-Al₂O₃ was more active for H₂ production than the catalyst supported on -Al₂O₃. Metal loading did not affect the catalytic performance. The alternative activation method with CH₄/O₂ mixture affected differently the activity and stability of the Ni/γ-Al₂O₃ and the Ni/-Al₂O₃ catalyst. This activation method increased significantly the stability of Ni/-Al₂O₃ compared to H₂ reduction. SEM and TG/DTA analysis indicate the formation of filamentous carbon during the CH₄/O₂ activation step, which is associated with the increasing catalyst activity and stability. The effect of temperature on the type of carbon formed was investigated; indicating that filamentous coke increased activity while encapsulating coke promoted deactivation. A discussion about carbon formation and the influence on the activity is presented.     

NO reduction by CH4 in the presence of O2 over La2O3 supported on Al2O3

Dispersing La₂O₃ on δ- or γ-Al₂O₃ significantly enhances the rate of NO reduction by CH₄ in 1% O₂, compared to unsupported La₂O₃. Typically, no bend-over in activity occurs between 500° and 700°C, and the rate at 700°C is 60% higher than that with a Co/ZSM-5 catalyst. The final activity was dependent upon the La₂O₃ precursor used, the pretreatment, and the La₂O₃ loading. The most active family of catalysts consisted of La₂O₃ on γ-Al₂O₃ prepared with lanthanum acetate and calcined at 750°C for 10 h. A maximum in rate (mol/s/g) and specific activity (mol/s/m²) occurred between the addition of one and two theoretical monolayers of La₂O₃ on the γ-Al₂O₃ surface. The best catalyst, 40% La₂O₃/γ-Al₂O₃, had a turnover frequency at 700°C of 0.05 s⁻¹, based on NO chemisorption at 25°C, which was 15 times higher than that for Co/ZSM-5. These La₂O₃/Al₂O₃ catalysts exhibited stable activity under high conversion conditions as well as high CH₄ selectivity (CH₄ + NO vs. CH₄ + O₂). The addition of Sr to a 20% La₂O₃/γ-Al₂O₃ sample increased activity, and a maximum rate enhancement of 45% was obtained at a SrO loading of 5%. In contrast, addition of SO⁼₄ to the latter Sr-promoted La₂O₃/Al₂O₃ catalyst decreased activity although sulfate increased the activity of Sr-promoted La₂O₃. Dispersing La₂O₃ on SiO₂ produced catalysts with extremely low specific activities, and rates were even lower than with pure La₂O₃. This is presumably due to water sensitivity and silicate formation. The La₂O₃/Al₂O₃ catalysts are anticipated to show sufficient hydrothermal stability to allow their use in certain high-temperature applications.     

Hydrogenation of naphthalene on NiMo- Ni- and Ru/Al2O3 catalysts: Langmuir–Hinshelwood kinetic modelling

The importance of the hydrodearomatisation (HDA) is increasing together with tightening legislation of fuel quality and exhaust emissions. The present study focuses on hydrogenation (HYD) kinetics of the model aromatic compound naphthalene, found in typical diesel fraction, in n-hexadecane over a NiMo (nickel molybdenum), Ni (nickel) and Ru (ruthenium) supported on trilobe alumina (Al₂O₃) catalysts. Kinetic reaction expressions based on the mechanistic Langmuir–Hinshelwood (L–H) model were derived and tested by regressing the experimental data that translated the effect of both naphthalene and hydrogen concentration at a constant temperature (523.15 and 573.15 K over the NiMo catalyst and at 373.15 K over the Ni and Ru/Al₂O₃ catalysts) on the initial reaction rate. The L–H equation, giving an adequate fit to the experimental data with physically meaningful parameters, suggested a competitive adsorption between hydrogen and naphthalene over the presulphided NiMo catalyst and a non-competitive adsorption between these two reactants over the prereduced Ni and Ru/Al₂O₃ catalysts. In addition, the adsorption constant values indicated that the prereduced Ru catalyst was a much more active catalyst towards naphthalene HYD than the prereduced Ni/Al₂O₃ or the presulphided NiMo/Al₂O₃ catalyst.     

前驱体对Ru/CeO_2-ZrO_2-Al_2O_3催化剂CO选择性甲烷化的影响

以CeO_2-ZrO_2-Al_2O_3复合氧化物为载体,采用分步等体积浸渍法制备了不同Ru负载量及不同Ru前驱体的催化剂,并考察了这些因素对催化剂CO选择性甲烷化活性及为燃料电池供氢操作温度窗口的影响。结果表明,Ru负载量为1%的催化剂具有较好的CO选择性甲烷化活性及最宽的操作温度窗口;以Ru(NO)(NO_3)_3为前驱体制备的催化剂,Ru金属分散度较差,低温CO甲烷化活性较低,高温CO甲烷化选择性较差,操作温度窗口仅为15℃;以RuCl_3·xH_2O为前驱体制备的催化剂具有良好的CO选择性、甲烷化活性及60℃操作温度窗口,且水洗除氯操作对催化剂性能影响不明显。     

Comparison of catalytic activity and selectivity of Pd/(OSC + Al2O3) and (Pd + OSC)/Al2O3 catalysts

The effect of the Pd addition method into the fresh Pd/(OSC + Al₂O₃) and (Pd + OSC)/Al₂O₃ catalysts (OSC material = Ce_xZr_1−xO₂ mixed oxides) was investigated in this study. The CO + NO and CO + NO + O₂ model reactions were studied over fresh and aged catalysts. The differences in the fresh catalysts were insignificant compared to the aged catalysts. During the CO + NO reaction, only small differences were observed in the behaviour of the fresh catalysts. The light-off temperature of CO was about 20 °C lower for the fresh Pd/(OSC + Al₂O₃) catalyst than for the fresh (Pd + OSC)/Al₂O₃ catalyst during the CO + NO + O₂ reaction. For the aged catalysts lower NO reduction and CO oxidation activities were observed, as expected. Pd on OSC-containing alumina was more active than Pd on OSC material after the agings. The activity decline is due to a decrease in the number of active sites on the surface, which was observed as a larger Pd particle size for aged catalysts than for fresh catalysts. In addition, the oxygen storage capacity of the aged Pd/(OSC + Al₂O₃) catalyst was higher than that of the (Pd + OSC)/Al₂O₃ catalyst.     

Modelling of citral hydrogenation kinetics on an Ni/Al2O3 catalyst

The kinetics of citral hydrogenation in ethanol over an Ni/Al₂O₃ catalyst was studied in a slurry reactor operating at atmospheric pressure and at a temperature range of 60–77°C. Citronellal was the primary reaction product, whereas the amounts of unsaturated alcohols were very minor. Citronellol was the dominating product, generated mainly through the hydrogenation of the carbonyl group of citronellal. Based on the experimental data, a kinetic model was developed for hydrogenation. The model comprises competitive and rapid adsorption steps as well as rate-determining hydrogenation steps. The mass transfer limitation of hydrogen was included in the mathematical model. The kinetic parameters and the mass transfer parameter of hydrogen were estimated from the experimental data. A comparison of the model predictions with the experimental data revealed that the proposed kinetic approach gave a satisfactory reproduction of the data.