Co-Ru/γ-Al2O3 Catalyst Modified With ZrO2 for Fischer-Tropsch Synthesis

Abstract

Using an incipient impregnation method, a Co-Ru bimetallic catalyst was prepared. The effects of the ZrO₂ modification of support on heavy hydrocarbon synthesis were investigated in a fixed-bed reactor. The results indicated that the ZrO₂ modification could block defects of γ-Al₂O₃ crystal lattice, weaken the interaction between support and Co, and hinder or prevent the formation of cobalt aluminate. Zr reacted with Co to form the Co-Zr species, which is easily reduced under lower temperature. It caused an increase in the amount of easily reducible Co species and a decrease in the amount of uneasily reducible Co species. Then the reduction extent of cobalt-based catalyst was raised under the typical reduction condition. Meanwhile, support of γ-Al₂O₃ was modified with ZrO₂, and the interface of Co-ZrO₂ formed. The Co-ZrO₂ interface led to an increase of the intensity of the bridge-form CO adsorption, which CO facilitates to be dissociated. At H₂/CO molar ratio in feed 2.0, 503 K, 1.5 MPa, and 800 hr^?1, the catalyst exhibited better catalytic performance. The CO conversion was 93.27%, the C₅ ⁺ selectivity was 82.56%, and the chain growth factor was 0.81.     

Co-CeO_2/SiO_2 Fischer-Tropsch Synthesis Catalyst

1. Introduction The Fischer-Tropsch synthesis (FTS) is an attractive route to produce liquid hydrocarbons from abundant natural gas via synthesis gas due to the increasing prices of oil and environmental problems. Cobalt based catalysts have been widely u…     

Production of Lubricating Base Oil Using a Moist SiO2/γ-Al2 O3 Catalyst

Abstract

The catalyst SiO₂/γ-Al₂ O₃ treated by micro-wetness air to produce lubricating base oil was studied in this article. The satisfactory reaction temperature, the treatment temperature, and the proper content of active composition was researched. Under the best reaction conditions with a reaction temperature of 170°C, a reaction pressure at 6.0 Mpa, the volume velocity at 0.5 h^?1. The polymerization of α-olefin was performed at a microreactor and produced lubricating base oil with the kinetic viscosity at 38.19 mm² · s^?1, the bromine number at 5.78 g(Br) · (100 g)^?1, and the pour point at ?43.0°C. Then the structure of the catalyst was determined by Brunauer, Emmett and Teller (BET) technology. The result shows that when the optimal micro-wetness air was 45°C, the reaction temperature was 800°C, and the amount of active composition was 12%, and the catalyst has high catalytic activity and wide market prospect.     

Study on Synthesis and Catalytic Performance of Hierarchical Zeolite

A kind of hierarchical zeolite catalyst was synthesized by hydrothermal method. X-ray diffraction （XRD） and nitrogen adsorption-desorption method were used to study the phase and aperture structure o（ the prepared catalyst. Infrared （IR） spectra of pyridine adsorbed on the sample showed that the hierarchical zeolite really had much more Bronsted and Lewis acidic sites than the HZSM-5 zeolite. The catalytic cracking of large hydrocarbon molecules showed that the hierarchical zeolite had a higher catalytic activity than the HZSM-5 zeolite.     

Modeling of Coke Formation and Catalyst Deactivation in Propane Dehydrogenation Over a Commercial Pt-Sn/γ-Al2O3 Catalyst

Propane dehydrogenation was carried over a commercial Pt-Sn/γ-Al₂O₃ catalyst at atmospheric pressure and reaction temperatures of 580, 600, and 620°C and WHSV of 11 h^?1 in an experimental tubular quartz reactor. Propane conversions were measured for catalyst time on stream of up to nine days. The amounts of coke deposited on the catalyst were measured after one, three, six, and nine days on stream using a thermogravimetric differential thermal analyzer (TG-DTA) for each reaction temperature. The coke formation kinetics was successfully described by a coke formation model based on a monolayer-multilayer mechanism. In addition, catalyst deactivation was presented by a time-dependant deactivation function. The kinetic order for monolayer coke formation was found to be two, which would support a coke formation step involving two active sites. The kinetic order for multilayer coke formation was found to be zero. The activation energy for monolayer coke formation was found to be 29.1 kJ/mol, which was lower than the activation energy of about 265.1 kJ/mol for multilayer coke formation indicating that the presence of metals can promote coke formation on the catalyst surface.     

不同助剂改性γ-Al2O3对WNi/γ-Al2O3催化剂性能的影响

采用表面浸渍法用B,P,Ti,Zr4种助剂对Al2O3表面进行化学改性。采用浸渍法将活性金属负载到改性Al2O3载体上,获得WNi/γ-Al2O3催化剂。运用X射线衍射、红外光谱、程序升温还原等手段表征了改性γ-Al2O3和WNi/γ-Al2O3催化剂的性能。以正十二烷为原料,考察了4种助改性剂对WNi/γ-Al2O3催化剂加氢裂化活性和选择性的影响。结果表明,4种助剂的改性效果不同,P改性Al2O3的比表面积比其他3种改性剂改性的比表面积大,改性前后晶体的结构没有发生显著变化;P改性WNi/γ-Al2O3催化剂的总酸量显著降低;Ti能够大幅度降低WNi/γ-Al2O3催化剂的还原温度;Zr改性WNi/γ-Al2O3催化剂的转化率显著降低。     

Study on the Performance of Regenerated Catalyst for Ammonoximation of Cyclohexanone

The study on the deactivated catalyst and the regenerated catalyst for the 70 kt/a cyclohexanone ammonoximation commercial test unit had revealed that addition of a proper amount of silicon additive could suppress the solubilization-induced loss of silicon in catalyst while providing protection to the catalyst. Compared to the direct calcination method for catalyst regeneration, adoption of the regeneration method through pretreatment-calcination of catalyst could be more beneficial to the restoration of catalyst channels and enhancement of the performance of the regenerated catalyst, which could be repeatedly regenerated and utilized. The outcome of commercial scale testing of the catalyst had indicated the good performance of the regenerated catalyst, which could be used for four times, resulting in a reduction of the production cost of cyclohexanone-oxime in big chunks.     

Kinetic Models for Hydrogenolysis of Thiophene on Co-Mo/γ-Alumina Catalyst

Abstract

A feasible, comprehensive, and rigorous mechanistic kinetic model was developed for hydrogenolysis of thiophene on a commercial hydrodesulphurization Co-Mo/γ-Al₂O₃ catalyst. The kinetics were modeled with 24 rate expressions based on three modes of adsorption: molecular and atomic adsorption of hydrogen, and Eley Rideal mechanism. The experimental data were obtained in a bench-scale tubular reactor with plug flow, and the conditions varied over the following range: total pressure, P _t = 2–30 bar, temperature = 533–625 K, and molar hydrogen to hydrocarbon ratios 4–9. The experimental rate data were described by a set of Lagmuir-Hinshelwood-Hougen-Watson rate equations for both the hydrogenolysis of thiophene to butene and the hydrogenation of butene to butane on two different sites, σ and τ. The kinetic rate constants and adsorption equilibrium constants were estimated for each model using the optimization routine of Nelder-Mead simplex algorithm. Discrimination among rival models was based upon physicochemical criteria, analysis of the residuals, and statistical tests. The surface reaction between adsorbed thiophene and adsorbed hydrogen on σ sites in the hydrogenolysis, and the surface reaction between adsorbed butene and adsorbed hydrogen on τ sites in the hydrogenation when hydrogen is adsorbed molecularly are found to be the rate-determining steps. The predicted activation energies, enthalpies of adsorption, Gibbs free energies, and adsorption entropies compare exceedingly well with previously reported values in the literature.     

Mo/γ-Al2O3表面H2的吸附性能

利用H2与探针分子吸附的原位红外光谱技术，研究了担载Mo的质量分数为15％的Mo／γ-Al2O3催化剂表面的H2吸附。结果表明，还原态的Mo／γ-Al2O3催化剂表面可以形成多种配位不饱和Mo中心（Mo（CUS）），H2易在由桥式Mo-O-Mo键还原形成的Mo（CUS）上吸附。在323K下，H2主要以质子形式可逆吸附在Mo金属的表面；在较高温度下（573K），H2解离吸附在Mo（CUS）上，产生活化氢，使催化剂表面吸附物种发生加氢反应。证实H2与探针分子的交替吸附及共吸附的实验可以有效地提供Mo／γ-Al2O3催化剂表面H2吸附的信息。     

SO2在Fe2O3-CeO2/γ-Al2O3上的催化还原

研究了γ-Al2O3上浸渍不同金属催化剂催化CO还原SO2的反应,结果发现,Fe2O3/γ-Al2O3具有最高的催化活性,在Fe2O3/γ-Al2O3基础上引入具有较高氧空位和氧流动性的CeO2,催化剂的活性得到进一步的提高,主要是由于两活性物种Fe和Ce有着某种协同作用.不同方法制备的Fe2O3/γ-Al2O3的催化活性也不同,采用溶胶-凝胶法制备的催化剂的活性最好,可能是由于溶胶-凝胶法使催化剂表面的活性物种分布更均匀.     

Ni-Cu/γ-Al2O3催化剂上苯加氢制环己烷

制备了一系列不同原子比的镍铜催化剂.测定了该系列催化剂对苯加氢制环己烷的催化活性;考察了镍铜原子比、镍铜负载量、还原温度和浸渍方式对苯加氢制环己烷反应的影响.结果表明添加金属铜后,催化剂的还原温度降低,活性较好.以镍含量12.5%,镍铜原子比为1/1,镍铜共浸制备的催化剂较好.     

Pt/γ-Al2O3催化剂催化微晶纤维素转化

以γ-Al2O3为载体,采用浸渍法制备了一系列Pt负载量不同的Pt/γ-Al2O3催化剂,研究了Pt/γ-Al2O3催化剂催化微晶纤维素转化的性能及反应机理,考察了反应温度、H2压力、搅拌转速和Pt负载量对微晶纤维素转化率的影响,并对Pt/γ-Al2O3催化剂的稳定性进行了测试。实验结果表明,微晶纤维素的转化率随反应温度、H2压力、搅拌转速和Pt负载量的增加而增加,在Pt的质量分数5.0%、温度190℃、H2压力5MPa、搅拌转速550r/min条件下,微晶纤维素转化率可达40.7%;但升高反应温度为反应提供了过高的能量,促进了副反应的发生,反应温度最好控制在200℃以下。Pt/γ-Al2O3催化剂的重复使用性较好,经4次回收利用,活性没有明显下降。     

Mechanistic Kinetic Models for Hydrogenolysis of Benzothiophene on Co-Mo/γ-Alumina Catalyst

Abstract

A feasible, comprehensive, and rigorous mechanistic kinetic model was developed for hydrogenolysis of benzothiophene on a commercial Co-Mo/γ-Al₂O₃ catalyst. The kinetics was modelled with 28-rate expressions based on molecular and atomic adsorption of hydrogen. The kinetic parameters were estimated for each model using the optimization routine of the Nelder—Mead simplex algorithm. Discrimination among rival models was based on physicochemical criteria, analysis of residuals, and statistical tests. The surface reaction between adsorbed benzothiophene and adsorbed hydrogen on σ sites in the direct hydrogenolysis of benzothiophene to ethylbenzene, the surface reaction between adsorbed benzothiophene and adsorbed hydrogen on τ sites in the hydrogenation of benzothiophene to dihydrobenzothiophene, and the surface reaction between adsorbed dihydrobenzothiophene and adsorbed hydrogen on σ site in the hydrogenolysis of dihydrobenzothiophene to ethylbenzene when hydrogen is adsorbed atomically are found to be the rate-determining steps. The predicted activation energies and enthalpies of adsorption compare exceedingly well with previously reported values in the literature.     

Analysis for surface coke deposition in used Mo-Co/γ-Al2O3 catalyst for diesel hydrodesulfurization

The coked Mo-Co/γ-Al₂O₃ catalysts were Soxhlet extracted with the solvent of tetrahydrofuran. Experimental techniques like FT-IR, GC-MS, XPS, H₂-TPR, BET, etc. were applied for the characterization of coke and catalysts to make a comparison of their physical properties. The results showed that the active components of the catalyst were slightly less after the reaction. The specific surface area and the pore volume had recovered to some degree. These results indicated that the main cause of deactivation of Mo-Co/γ-Al₂O₃ catalysts is carbon deposit. The principal components of the soluble carbon deposit on Mo-Co/γ-Al₂O₃ catalysts were alkyl aromatics with 1–4 rings and C₁₉–C₂₉ long-chain alkane compounds.     

Ga2O3/γ-Al2O3表面丙烷选择性还原NO的反应机理研究

对不同催化剂的制备方法及催化剂中镓含量对催化剂活性的影响进行了研究,对Ga2O3/γ-Al2O3催化剂中的活性中心进行了讨论;用原位红外技术、暂态反应技术、程序升温脱附和程序升温表面反应等方法对Ga2O3/γ-Al2O3表面丙烷选择性还原NO的反应机理进行了研究.对催化剂表面各吸附物种的形成和反应性能、NO对丙烷氧化的影响进行了详细的研究,实验结果与化学计量学计算结果相结合可以推测出哪些吸附物种涉及NO的选择性还原,哪些吸附物种没有参与NO的还原反应,从而推断出在Ga2O3/γ-Al2O3催化剂表面丙烷选择性还原NO的反应机理.     

以水合Al2O3为基体合成MCM-41/γ-Al2O3复合材料

以γ-Al2O3的水合产物薄水铝石为基体，以十六烷基三甲基溴化铵（CTMABγ）为模板剂，以水玻璃为硅源．采用原位合成方法水热制备了高热稳定性的MCM-41／γ-Al2O3复合材料。考察了γ-Al2O3的水合时间、水合温度和MCM-41合成母液的pH值、晶化温度等对复合材料中MCM-41性质的影响。对γ-Al2O3的水合产物和复合材料进行了X射线衍射（XRD）、扫描电子显微镜（SEM）和低温N2吸附表征。结果表明，提高水合温度或延长水合时间，γ-Al2O3逐渐水合为尺寸均一的条状薄水铝石，且其孔径增大；以薄水铝石为基体合成的MCM-41/γ-Al2O3复合材料中MCM-41的相对结晶度增加，热稳定性显著改善；MCM-41／γ-Al2O3复合材料较佳的合成条件为：γ-Al2O3的水合时间24h，水合温度150℃，合成母液的pH值11．0，晶化温度150℃。薄水铝石在合成母液中的溶解性是影响复合材料中MCM-41性能的主要因素。     

MgO/γ-Al2O3催化酯交换合成碳酸甲丁酯

通过活性组分和载体筛选制备了MgO/γ-Al_2O_3催化剂,用于碳酸二甲酯(DMC)和正丁醇液相酯交换反应合成碳酸甲丁酯(BMC),并考察了活性组分前驱物、催化剂焙烧温度和活性组分负载量对催化剂活性的影响。结果表明,以Mg(OAc)_2·4H_2O为活性组分前驱物,催化剂焙烧温度为400℃,活性组分MgO负载量为5%时,MgO/γ-Al_2O_3表现出高的酯交换反应催化活性。同时考察了反应温度、原料配比对酯交换反应的影响,适宜的反应温度为100℃;物料配比n(DMC):n(正丁醇)=3:1时,正丁醇的转化率达到98.4%,BMC的选择性为91.9%,收率为90.4%。催化剂重复实验表明催化剂重复使用性能良好。     

助剂对WP/γ-Al2O3催化剂性能的影响

 采用浸渍法和H₂气流中磷化还原法制备了一系列负载 30%WO₃和各种不同含量Ni、Co、V助剂的WP/γ-Al₂O₃, 并采用XRD、NH₃-TPD、XPS手段和高压微反装置对它们进行表征和催化活性评价,考察助剂Ni、Co和V对WP/γ-Al₂O₃催化剂物化性质和催化性能的影响. 结果表明, 加入适量的助剂Ni(3%～5%)、Co(5%～7%)和V(1%～3%)能够改善WP/γ-Al₂O₃催化剂表面上活性组分的分散性和增加WP/γ-Al₂O₃催化剂的比表面积. 助剂Ni和Co的加入使WP/γ-Al₂O₃催化剂表面上低价W物种数量增多.而助剂V的加入使WP/γ-Al₂O₃催化剂表面上低价W物种数量减少. 在高温(360℃)下咔唑加氢脱氮(HDN)反应中和低温(300℃)下的二苯并噻吩(DBT)加氢脱硫(HDS)反应中, WP/γ-Al₂O₃催化剂分别具有优良的HDN和HDS活性. 含有更高的DBT的HDS活性. 在较高温度(360℃)下DBT的HDS反应中, 含1%V的V-WP/γ-Al₂O₃催化剂的HDS活性高于WP/γ-Al₂O₃催化剂. 助剂Ni和Co明显促进了WP/γ-Al₂O₃催化剂在咔唑HDN反应中的活性, Ni助剂的助催化作用比Co更明显.含7%Ni的Ni-WP/γ-Al₂O₃催化剂和含5%Co的Co-WP/γ-Al₂O₃催化剂在300℃咔唑HDN反应中HDN活性很高. 加入1%的V可以提高WP/γ-Al₂O₃催化剂在咔唑HDN反应中尤其在360℃下咔唑HDN反应中的HDN活性.     

低温Ni-Fe/γ-Al2O3催化剂乙醇水蒸气重整制氢

考察了Ni-Fe/γ-Al2O3催化剂低温下乙醇水蒸气重整制氢的性能.结果表明,在低温下Ni-Fe/γ-Al2O3催化剂对乙醇水蒸气重整制氢表现出高的乙醇转化率和较好的氢气选择性以及较高的稳定性.723 K、H2O/EtOH摩尔比=13、液体空速(LHSV)=2 0～2.9 h-1时,乙醇完全转化,氢气的选择性达到98%以上.     

The Modeling of Kinetics and Catalyst Deactivation in Propane Dehydrogenation Over Pt-Sn/γ-Al2O3 in Presence of Water as an Oxygenated Additive

A reduction in catalyst's activity with time-on-stream and the formation of side products are two of the problems associated with catalytic propane dehydrogenation (PDH). Previous studies have indicated that the presence of small amounts of oxygenated additives such as water can reduce coke formation and enhance catalyst activity. The aim of the present work was to develop an appropriate kinetic model for PDH over a commercial Pt–Sn/γ-Al₂O₃ catalyst in the presence of small amounts of water. Experimental data were obtained from a previous study where catalytic PDH was carried out in a bench scale reactor system at atmospheric pressure in the temperature range of 575–620°C in the presence of different amounts of water. The kinetics of the main dehydrogenation reaction were described in terms of a Langmuir-Hinshelwood rate expression and the effects of water on coke deposition and catalyst sintering were considered in a catalyst deactivation model to explain the observed optimum level in the amount of added water.