HYDROGEN SULFIDE POISONING OF METHANOL SYNTHESIS Cu-BASED CATALYST (III) EFFECTIVENESS FACTOR OF POISONED CATALYST

The single component model and the multicomponent model of the effectiveness factor ζ_d, of the poisoned catalyst have been proposed and solved by the orthogonal collocation method. The center equilibrium dead zone was founded in catalyst pellets. The calculated values ζ_d, were respectively 0·1229-0·2907,0·1298-0·2445 and 0·0690-0·2155 for No. 1, No. 2 and No. 3 catalyst. The average of the absolute values of the relative deviations between the experimental values and the calculated values by model for ζ_d was less than 11 per cent. The models can be used to calculate the effectiveness factor of the poisoned catalyst.     

ESTIMATION OF TOXIC COKE DEPOSITS ON FRESH AND REGENERATED Pt/Al2O3 CATALYST FROM METHYLCYCLOPENTANE REFORMING IN H2 AND N2 ATMOSPHERES.

An estimate of the quantity of toxic coke deposited on fresh and regenerated Pt/Alj₂O₃ catalyst has been determined for methylcyclopentane (MCP) reforming in a Berty CSTR at 390°C, W/F=0·11 g min cm^-3, total pressure of 1 atm and MCP partial pressure of 9·2 × 10^-2 atm in H₂ or N₂ carrier. Eleven cycles consisting each of catalyst deactivation, regeneration and reduction were investigated with 3 in H₂ and 8 in N₂. Oxidizable (primary) coke deposits were higher in N₂. However, higher levels of toxic (secondary) coke were deposited in H₂. The ratio of oxidizable to toxic coke lies between 1-15×10³ in H₂ and 22 - 55 × 10³ in N₂ The coke-time profiles for secondary coke removal exhibited maxima suggestive of three types of secondary coke with varying reactivity in H₂. Furthermore, the results strongly suggest that the cokes were layered on acidic coke forming sites with the solid phase transformation of primary to secondary coke occurring at the catalyst-coke interface.     

COMPARATIVE REACTION STUDY OF METHYLCYCLOHEXANE AND 3-METHYLHEXANE IN H2 AND N2 ON Pt/Al2O3 CATALYST

The reaction of methylcyclohexane and 3-methylhexane were studied in a pulse microcatalytic reactor using H₂ and N₂ carriers on Pt/Al₂O₃ catalyst at temperatures from 350 to 500°C, contact times (W/F) of 1.25 × 10^-3-3.75 × 10^-3 g min/ml and a total pressure of 4.0 kg/cm². In N₂, there was complete conversion of methylcyclohexane to methane, benzene and toluene while similar products were produced for 3-methylhexane, albeit with diminished conversion level. In H₂, methane was produced from 3-methylhexane conversion while aromatization without demethylation was obtained in addition to some cracking for methylcyclohexane at the low temperature range (350-400°C); a higher temperature range (460-500°C) resulted in complete fragmentation for methylcyclohexane. In H₂-N₂ mixtures, the presence of N₂ of not less than 50% in the carrier gas stream yielded an aromatic catalyst at conditions where only cracking activity was previously evident. The differences in product distribution and/or product types for the two reactants in H₂ and N₂ suggest a different reaction mechanism for both reactants.     

EFFECTS OF SUPPORTS ON THE ACTIVITY OF NICKEL CATALYST FOR CH4 REFORMING WITH CO2

Nickel catalyst is an effective catalyst for reforming CH₄ with CO₂. The reaction between CO₂ and CH₄ at 1073 K. in the pressure of 0·1 MPa has been studied over different materials supported nickel metal in a fixed-bed reactor. Different catalysts before and after reaction were characterized by SEM, XRD, XPS. Results shows that CO and H₂ are basically produced at the same ratio. When the feed ratio CO₂/CH₄ is less than 0·5, less C₂~C₄ hydrocarbons are detected. When the feed ratio CO₂/CH₄ is 1, Ni/a- Al₂O₃ catalyst has the highest activity. However, when the feed ratio CO₂/CH₄ is greater than 1, Ni/y- A1/O₃, Ni/a- A1₂O₃, Ni/SiO₂ and Ni/HZSM-5 had higher activity; Ni/clinoptilolite basically no activity. Different kinds of carbon deposit are established.     

EFFECTS OF OXYGEN ON THE FT SYNTHESIS OVER Fe-Cu-K CATALYST

The poisoning of commercial coprecipilated Fe-Cu-K catalyst by oxygen in the Fischer-Tropsch synthesis was investigated, since synthesis gas obtained by the gasification of coal contains O₂. The pretreated catalysts were oxidized in a oxygen-containing syngas.The effects of poisoning methods, reaction temperature, and oxygen fed to catalyst on the catalytic behavior of reduced Fe-Cu-K catalyst in a fixed bed were studied for synthesis tests with the ratio H₂/CO of 2.3 containing O₂ 5.16×10^-3 under 2.62 MPa and 524.2 K. The relative activity of catalyst exceeded 1 for the first few hours of poisoning by oxygen both in prepoisoning and poisoning in situ process, then decreased linearly with the increasing of oxygen fed to catalyst, and finally increased to the relative activity of 0.6-0.7. The activity decreased less rapidly poisoning in situ than that of prepoisoning. The gaseous hydrocarbons average molecular weight increased greatly when poisoned by oxygen. The wax weight percentage in products and the ratio of olefin to paraffin decreased as poisoned by oxygen. Oxygen also affects the composition of oils and the contents of oxygenated compounds formed in water phase.     

REACTION OF VISBREAKER BITUMENS WITH SULFUR

The utilization of sulfur in bituminous binders started many years ago: a number of roads were paved in U.S. with SA (sulfur-asphalt) mixtures. Literature reports that, when mixing sulfur and asphalt, H₂S evolution starts at temperatures higher than 150°C.

By using thermal analysis techniques, the present paper shows that H₂S evolution begins at about 130°C for most types of bitumens. Kinetics of reaction between sulfur and visbreaker bitumens were also studied: the reaction order with respect to sulfur is equal to 0.5 for the three visbreaker bitumens considered in this work.     

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用多次浸渍法制备了Ｐｔ－Ｓｎ－Ｋ／Ａｌ２Ｏ３丙烷催化脱氢制丙烯催化剂，该催化剂Ｐｔ含量小于０．４５％（质量），制备容易，重复性好，分别在催化剂装置为２ｍＬ和１００ｍＬ的试验装置上考察了其长周期运转情况。     

催化裂化催化剂积炭的杂原子组成及其再生转化机理

以不同工艺条件下的催化裂化待生、再生催化剂及催化剂再生烟气为研究对象,分析催化剂积炭的杂原子组成。依据密度泛函理论,利用Gaussian 09软件在B3LYP/def2-TZVP水平下对积炭中典型的含氮、含硫化合物进行几何优化,得到其最稳定构型;以Laplacian键级为判据,研究积炭中杂原子的转化机理。结果表明：催化剂积炭中的含氮化合物主要是吡啶类、吡咯类和季胺类化合物,含硫化合物主要是噻吩类化合物;催化剂再生初期,含氮化合物以∶NH和·CN的形式逸出,主要转化成NH₃和HCN;含硫化合物以·HS和∶S等形式逸出,主要转化为H₂S、COS;随着再生过程的进行,NH₃、HCN和H₂S、COS最终分别转化为NO_x和SO_x。模拟结果与不同再生工艺条件下再生烟气组成一致。     

HYDROGEN SULFIDE POISONING OF METHANOL SYNTHESIS Cu-BASED CATALYST (I) INTRINSIC DEACTIVATION KINETICS

The hydrogen sulfide poisoning of the methanol synthesis C207Cu-based catalyst was investigated at atmospheric pressure, temperature 250 ∼265°C,hydrogen sulfide content 100-280 ppm, based on the methanol composition reaction. The higher the hydrogen sulfide content, the faster the rate of deactivation; the higher the temperature, the faster the rate of deactivation. The intrinsic deactivation rate equations were derived from the experimental data. In addition, the poisoned catalyst was measured by X-ray diffraction.     

V2O5-MoO3/TiO2催化剂脱硝性能的研究

通过挤压成型法制备了一系列蜂窝状V₂O₅-MoO₃/TiO₂催化剂。研究了钒、钼负载量对催化剂脱硝活性的影响,测试了催化剂抗硫和抗碱金属钠中毒的性能。采用X射线衍射、N₂吸附-脱附、扫描电子显微镜等表征手段,对新鲜催化剂和钠中毒催化剂的物理和化学性质进行分析。结果表明：当钒负载量（w）为1.5％～2.5％时,催化剂的脱硝性能随钒负载量的增加而提高;当钒负载量（w）为1.5%、钼负载量（w）为4.0％时,催化剂的脱硝性能最优;SO₂对V₂O₅-MoO₃/TiO₂催化剂的中毒作用是可逆的,可以通过热处理来恢复;当Na₂O负载量（w）为2.0％时,催化剂失活严重,这主要是由于钠盐在催化剂表面附聚而形成不规则的白色颗粒,覆盖了活性位点,导致催化剂的表面积减小,氧化还原性变差。同时,Na掺杂会影响催化剂中元素的化学状态和表面组成,降低V⁵⁺与化学吸附的O_α的比例。     

REFORMING OF N-OCTANE ON A Pt/Al2O 3 CATALYST. 1. PRODUCT DISTRIBUTION AND KINETIC ANALYSIS.

The conversion of n-octane on Pt/Al₂O₃ catalyst to hydrocracked products, isooctane, ethylbenzene, o-,p-,m-xylene and toluene was investigated in hydrogen in a Berty CSTR at three different partial pressures of n-octane, 101·325 KPa total pressure, temperatures between 400°C-460°C and W/F values up to 0·33gmincm^-3. The hydrocracked products were the most predominant. Of the other products, isooctane was present in the highest yield. A sequence of elementary steps based on the suggested reaction network of Ako and Susu (1986) was found to predict the experimental conversion-W/F data with the conversion of adsorbed isooctane to adsorbed o-xylene as the rate determining step. The activation energies for the forward and backward reactions of this step were determined to be 21·2 and 14·3 Kcal/gmol, respectively.     

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

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.     

KINETIC AND STRUCTURAL STUDIES OF CALCIUM-BASED SORBENTS FOR HIGH-TEMPERATURE COAL-GAS DESULFURIZATION

The absorption of H₂S by large particles of limestone, dolomitic limestone and dolomite (average mass-radius of 0·40 mm) was tested under simulated coal gases. Below the calcination temperature of CaCO₃ (about 900^°C under 1 bar of CO₂), complete conversion of the calcium carbonate to calcium sulfide can only be achieved with dolomite. Above the calcination temperature of CaCO₃, the conversion to CaS is complete for all three sorbents in about one hour when 10,000 ppm H₂S is present in the gas phase. Large particles of limestone thus appear to be a suitable sorbent for high-temperature coal-gas desulfurization (above about 900 ^°C). A mathematical model based on the kinetic information collected in this work predicts the desulfurization performance of a packed or moving bed of limestone particles. Finally, a low-temperature regeneration scheme for the spent sorbent (CaS) in which sulfur can be subsequently recovered as the element is suggested.     

高含硫钻井液缓蚀剂的合成及性能研究

本文合成了抑制H₂S腐蚀的咪唑啉类缓蚀剂,并研究了它们的性能。正交试验表明,最佳合成条件是:反应温度:190～200℃;酸:胺(mol比)=1:1.05;反应时间以3～5小时为宜。根据以上条件合成的缓蚀剂,在含有3200mg/lH₂S的泥浆中,用量为0.2%时,抑制效果能达到80～90%,与碱式碳酸锌复配使用时,能提高缓蚀效率和降低碱式碳酸锌的用量,并发现缓蚀剂与CaO之间具有明显的协同效应。泥浆流变性能试验表明,缓蚀剂能提高泥浆的动切力和动塑比,对失水量影响不大。此外,利用X-射线衍射试验证明:(1)低碳钢在含H₂S的泥浆中,腐蚀产物的主要组成为Fe₉S₆;(2)H₂S会破坏FCLS的稳定性,分解出Fe²⁺,与H₂S反应生成面心立方的Fe₂S₄。     

ALUMINA SUPPORTED Co-Mo OXIDES AS A CATALYST FOR HYDRODESULPHYRISATION OF ORGANIC SULFIDES AND DISULPHIDES (PART-I) USING STOPPED FLOW GAS CHROMATOGRAPHY

A model study on the hydrodesulphurization of dimethyl sulphide, di n-prophyl sulphide, di n-butyl sulphide and dimethyl disulphide on Co-Mo-A1₂O₃ surface was conducted using stopped-flow chromatographic technique. The plots for the rates of hydrocarbon formation agreed well with the first order reaction at the surface of the catalyst.

Activation energies for the hydrodesulphurization of (C₂H₅)₂S, (C₃H₇)₂S, n-(C₄H₉)₂S and (CH₃)₂S₂ are 57.55, 70.67, 72.74 and 37.80 Kj mole^-1 respectively.     

DEEP DESULPHURISATION OF A DIESEL BLEND IN A PILOT PLANT TRICKLE BED REACTOR

A pilot plant investigation was conducted to study the influence of hydrotreating conditions on conversion and characteristics of diesel blend and to determine the severity of operating conditions required to meet the proposed product specifications for diesel fuel in India. A typical diesel blend derived from various refinery streams with sulphur content of 2·06 wt% was hydrodesulphurised over a commercial NiO-MoO₃/Al₂O₃ catalyst in a pilot plant trickle bed reactor. The experiments were conducted at 300-370°C, 30-50 kg/cm², 2·0 3·0 hr^-1 liquid hourly space velocity and constant H₂/oil ratio of 185 m³/m³. The data showed that the diesel blend could be hydrotreated to meet revised product specifications of 0·25 wt% sulphur, 46 cetane number by increasing the severity of operation. The cetane number and aromatic saturation were limited by thermodynamic equilibrium at temperatures above 360°C. The influence of temperature was found to be more pronounced than that of pressure in the range of operating conditions studied.     

REFORMING OF N-OCTANE ON A Pt/Al2O3 CATALYST. II. KINETIC ANALYSIS OF HYDROGEN DEPENDENCE.

The conversion of n-octane on Pt/Al₂O₃ catalyst was found to pass through pronounced maxima with the variation of the partial pressure of hydrogen at temperatures between 420°C-460°C, P_N = 7·63 × 10^-3 atm and W/F = 0·11lg min cm_-3. The products of reaction were hydrocracked products, octane, ethylbenzene, o-.p-,m,-xylene and toluene. The order of appearance of the optimum PH for the various reactions were: Isooctane>Dehydrocyclized products>Hydrocracked products.

A sequence of elementary steps earlier postulated was found to predict the maximum in the n-octane P_H profiles for the three temperatures investigated. The rate determining steps for the two rate equations that were found suitable were conversion of adsorbed isooctane to adsorbed o-xylene and ethylbenzene.     

NiMoS加氢脱硫催化剂表面非化学计量硫物种动态平衡

加氢脱硫(HDS)催化剂NiMoS活性相表面非化学计量硫(S_x)物种的动态变化是HDS活性的决定因素。在HDS过程中,S_x物种处于动态平衡,且这一平衡与催化剂、H₂S分压及硫化温度相关。笔者采用程序升温的方法研究了催化剂载体、助剂Ni、硫化温度、H₂S分压对NiMoS催化剂表面S_x物种的影响。结果表明：催化剂载体对S_x物种的总量和还原性具有显著影响,Ni的引入显著促进S_x物种还原,提升HDS活性;硫化气相H₂S分压决定了催化剂表面S_x物种含量,气相中H₂S分压升高易使S_x物种增多,表面可利用NiMoS活性位减少,从而导致HDS活性降低。S_x物种含量与H₂S分压及硫化温度的关系符合热力学平衡及van′t Hoff等压方程,进一步将S_x物种含量与HDS反应速率系数进行关联,提出H₂S分压S_x物种含量HDS活性之间的定量关系。     

ARAB LIGHT CRUDE STUDY FOCUSES ON KINEMATIC VISCOSITY

Arab light crude oil has been characterized in terms of API gravity, total sulfur content, Reid vapor pressure, ash content, heating value, salt content, viscosity SUS, vanadium content as V₂O₅, pour point and analyses of various metals. The crude oil was fractionated into six true boiling point (TBP) fractions (IBP-95°C, 95-205°C, 205-260°C, 260-345°C, 345-455°C and 455°C+). These fractions were characterized in terms of API gravity, total sulfur, H₂S, mercaptan contents, molecular weight, elemental analyses for total carbon, hydrogen and nitrogen, and analyses of various metals. The kinematic viscosity data have been obtained for 95°C+ TBP fractions for a wide range of temperature up to 200°C.     

硫化氢生成模拟实验研究

利用封闭体系的高压釜实验装置进行硫化氢生成的模拟实验已有报道,但硫化氢的生成量很少或很难检测到。因此研制了开放体系的石英管模拟方法,探讨了硫酸钙、硫磺、黄铁矿分别与正己烷反应生成硫化氢以及低成熟泥灰岩生烃模拟过程中硫化氢的生成特征。结果表明,硫酸钙与正己烷在高温下可以发生反应,但反应比较困难,且硫化氢的生成量较少;单质硫与正己烷在较低温度下即可发生反应,并可生成大量的硫化氢;黄铁矿与正己烷可以发生反应并生成大量的硫化氢,主要是黄铁矿高温分解形成的单质硫与烃类反应的结果。低成熟泥灰岩生烃模拟过程中能够生成大量的硫化氢与其含有较多的黄铁矿有关。硫化氢生成的成功模拟为其成因机理研究提供了重要的实验手段和依据。