委内瑞拉减压渣油的热解特性及其动力学研究

采用热重 质谱(TG-MS)联用对委内瑞拉减压渣油在不同升温速率下进行热解实验,研究其热解反应特性,并采用3种等转化率法和分布活化能模型(DEAM)求取减压渣油热解反应的动力学参数。实验结果表明,委内瑞拉减压渣油的热解主要反应温度区间为179~490 ℃,总质量损失率为77.54%,质量损失峰值在446 ℃达到最大,最大质量损失速率为317.38μg/min。Flynn-Wall-Ozawa(FWO)法比其他2种等转化率法能更好地描述减压渣油的热解过程,由其计算得到的热解活化能为56.77~178.91 kJ/mol。进一步采用DEAM模型将减压渣油分为4个假定组分,对升温速率为10 ℃/min条件下的热重分析(TG-DTG)数据进行分峰拟合,求得饱和分、芳香分、胶质和沥青质四组分动力学参数,并据此获得减压渣油总活化能分布曲线。结果表明,委内瑞拉减压渣油活化能主要集中在100~250 kJ/mol范围内,通过加权求和获得平均活化能为190.11 kJ/mol。     

An improved gravimetric method applied to co-processing of polyethylene terephtalate and petroleum blend using HY zeolite as a catalyst

The co-processing of petroleum and polyethylene terephthalate (PET) was carried out in the presence and absence of a catalyst in an open vessel batch reactor at temperatures of 200, 300, 400, and 500 °C, which corresponds to temperatures of distillation and cracking. The catalyst used was the acidic HY zeolite, which is widely used in petroleum refining. The catalytic co-processing was carried out with the PET–oil charge, at a mass ratio of 1:1, containing 10% of HY zeolite. The conversion degree was measured by knowing the initial sample mass and amount of degraded material for each temperature and reaction time, using an improved gravimetric method consisting of a precision balance and an oven with a heating rate controller. The conversion values obtained were compared for petroleum and PET samples with and without the zeolite catalyst. At temperatures of 200 and 300 °C, the PET showed low conversions, about 5–10%. However, for the catalytic co-processing of PET–oil/HY at these same temperatures, an increase in conversion to about 25–30% was observed. At temperatures of 400 and 500 °C, conversions above 90% were obtained for the two samples, with a subsequent reduction in the activation energy, from 76 kJ mol^?1 (PET) to 56 kJ mol^?1 (PET–oil/HY). The decrease in the activation energy proved the efficiency of the HY zeolite and the synergistic effect when PET was blended to the oil for the catalytic co-processing, proving to be a viable alternative for the chemical recycling of PET in the petroleum industry.     

EFFECTS OF HEATING RATE AND PARTICLE SIZE ON THE PRODUCTS YIELDS FROM RAPID PYROLYSIS OF BEECH-WOOD

ABSTRACT

Effects of pyrolysis temperature (300–1000 ^°C), heating rates (100, 500, 1000, and 10,000 ^°C/s), and particle sizes (53–63,104–120,177–270, and 270–500 urn) on the yields and formation rates of tar, light oils, total gases, and char from pyrolysis of beech-wood under 1 atm helium pressure were studied. Wood particles were pyrolyzed in strips of stainless steel wire mesh in a captive sample apparatus; and yields of products were measured in weight percent of original wood as a function of temperature for different heating rates and particle sizes. The overall weight loss achieved from pyrolysis of this wood was about 90%. The total yields of tar and light oils from pyrolysis of this wood accounted for up to 80% of the original wood above 400 ^°C. Due to the post-pyrolysis reactions of tar and light oils, the tar and light oils yields go through a maximum with pyrolysis temperature for all particle sizes and most heating rates studied here. As particle size increases from 53–63 μm to 270–500 μm the maximum tar yield decreases from 53% to about 38%. The maximum tar yield also decreases with increasing the heating rate from 70% at 100 ^°C/s to 48% at 10,000 ^°C/s heating rate. Theses results indicate that as the intra-panicle post-pyrolysis cracking reactions of tar increases at higher heating rates and with larger particles the tar yield decreases. Tar was also analyzed with GPC for the effects of above pyrolysis parameters on the tar molecular weight. The tar average molecular weight. remains relatively constant (M_w = 300 amu, M_n = 155 amu, and M_z = 483 amu) under helium atmosphere with pyrolysis temperature at 1000 ^°C/s heating rate and with 53/63 u m particle size. The average molecular weight of tar does not significantly varies with heaung rate, but it decreases as the particle size increases.     

DESULPHURIZATION OF A TURKISH LIGNITE BY PYROLYSIS COMPARISION OF SLOW AND FLASH PYROLYSIS

ABSTRACT

To observe the effect of the heating rate on the desulphurization. Bolu- Mengen lignite was desulphurized in the temperature range of 450-750 °C using flash and slow pyrolysis methods. A reduction of 57.6 % and 34.2 % In the total sulphur was obtained for the slow and flash pyrolysis at a pyrolysis temperature of 750 °C. respectively. It was observed that the flash pyrolysis is shifted toward higher temperatures with respect to the slow pyrolysis. The flash pyrolysis having high thermal efficiency has a potential as a desulphurization process.     

An upgraded bio-oil produced from sugarcane bagasse via the use of HZSM-5 zeolite catalyst

The pyrolysis upgrading of bio-oil from sugarcane bagasse (SB) using ZSM-5 zeolite catalyst was carried out in a fixed bed reactor to determine the effects of heating rate, temperature, and catalyst/biomass ratio on yield of bio-oil and their chemical compositions. Proximate analysis indicated that SB has 13.2% moisture content. The ultimate analysis carried out established that the percentage of carbon content is higher (48.2%) than oxygen content (44%) while the fibre content analysis showed 26.4% lignin, 33.3% cellulose, 30.1% hemicellulose. The heating rate, temperature and catalyst/biomass ratio were varied in the range of 10–50 °C/min, 400–600 °C and 0.05–0.25 respectively. The non-catalytic pyrolysis gave the maximum percentage yield (45.67 wt%) of bio-oil at a pyrolysis temperature of 600 °C, heating rate of 50 °C/min, sweeping gas flow rate of 40 mL/min and the catalytic pyrolysis gave 40.83 wt% of bio-oil at the same conditions. The FT-IR spectra showed that the non-catalytic bio-oil is dominated by oxygenated compounds (acids, ketones, aldehydes, alcohols), while the catalytic bio-oil had preponderances of desirable compounds (alkanes, alkenes, aromatics, phenols). The chemical composition of the bio-oils was analyzed using GC–MS, which revealed that the quality of the bio-oil has been improved using HZSM-5 catalyzed pyrolysis.     

煤焦油渣热解特性及动力学分析

采用热重-红外(TG-FTIR)联用技术研究了煤焦油渣在不同升温速率(8、25、50 ℃/min)下的热解特性,得到热解反应特征参数;并利用Freeman-Carroll模型对热解过程进行动力学分析。结果表明：升温速率对煤焦油渣热解反应特征参数具有正相关的影响;对于热解过程,热重曲线呈现明显的三段式分布,升温速率对挥发分的总析出量影响不大;适当提高升温速率使热解产物释放更加集中,挥发分释放更加剧烈,热解速率加快;但过高的升温速率则使挥发分短时间集中释放,颗粒内挥发分与煤焦的接触几率增大,促进了二次反应,二次反应产物沉积在煤焦表面,反而使煤焦产率增大;煤焦油渣的热解反应活化能随升温速率的增加而增大,呈正相关性,适宜的升温速率有利于挥发分的析出和二次反应的发生;热解反应动力学参数在整个反应区间线性拟合效果较好,不同升温速率下的活化能和指前因子存在较好的动力学补偿关系。     

Direct conversion of an agricultural solid waste to hydrocarbon gases via the pyrolysis technique

The increased awareness toward the global warming and the environmental pollution problems has stimulated the utilization of the alternative energy sources since they can positively take part in minimizing such problems. Among these sources, biomass based solid wastes is counted as one of the most promising in the field of energy production. Thus, the current research work focuses on the conversion of rice straw (a biomass-based solid waste) into hydrocarbon gases in general and methane (main constituent of natural gas) in particular. The reduction of the operational temperature and the elevated rate of solid-to-gas conversion are newly presented approaches in this research. Specifically, the used operating temperature, in this study, had been 250?°C while the well-known temperature range for slow pyrolysis is 380–550?°C. Another approach is represented in this work via the orientation of the obtained biogas to become mainly hydrocarbon gases instead of CO, CO₂ and CH₄ mixture, as the common for such pyrolysis processes. The attained high rate of solid-to-gas conversion (80%) while at low temperature is also a new approach of this study since such high rate is just possible in the flash pyrolysis (750–900?°C). The increased conversion rate was achieved via reducing the particles size of the used solid-biomass to a nano-sized range.     

The chemical structure and the kinetics research of oil-wet oil sand from Kazakhstan during pyrolysis process

The pyrolysis experiments on the oil sands from Kazakhstan were carried out in a batch reactor. The FT-IR spectrum and the ¹H-NMR spectrum of pyrolysis oil under different temperatures were carried out to investigate the changes of functional group with temperature. The TGA experiments of oil sand were performed at different heating rates of 5, 10, 15, and 20°C/min up to 600°C. The Coats–Redfern method was accepted to calculate the kinetic parameters (apparent activation energy E and frequency factor A) of the desorption stage and the thermal cracking stage, respectively.     

Thermogravimetric analysis and kinetic study of heavy oil pyrolysis

Pyrolysis, so-called devolatilization, is one of the first steps of all thermochemical processes occurring in an inert atmosphere. The authors discuss the main kinetic features of heavy oil pyrolysis, on the basis of the data derived m from a TGA analysis and by using a kinetic model. The samples were heated over a range of temperature from 400 K to 430°C at various heating rates between 10 and 80°C/min. Experimental results showed that the effect of time is considerable in the case of tar conversion, compared to char and gases.     

催化裂化油浆基缩合多环多核芳香烃树脂的热解过程及动力学研究

采用TG和DTG,在不同升温速率（10、 20 和 30 K min-1）下考察了缩合多核芳烃（COPNA）树脂的热解机理和动力学。采用FT-IR、SEM和元素分析研究了COPNA树脂经不同热处理温度（200、400和600 °C）后官能团、微观结构和元素组成的变化。结果表明,热解过程可以分为三个阶段:初始失重阶段（225–450 °C）、第二失重阶段（450–560 °C）和热稳定阶段（>560 °C）。加热速率对热解过程有影响,热失重初始温度Ti、热失重终止温度Tf和最大失重速率Tmax等热力学参数随着加热速率的增加而升高。随着热处理温度的提高,芳香环上的脂肪侧链和取代官能团逐渐减少,C/H比和气孔率升高。热解动力学研究表明,初始失重阶段和第二失重阶段的活化能分布分别为150–210 kJ/mol和210–275 kJ/mol,这表明两个失重阶段的热解机理不同。当活化能低于250kJ/mol时,指前因子k0的值介于1011 和1018 s-1之间,而当活化能高于250 kJ/mol时,指前因子k0随着活化能E线性增加。     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

ABSTRACT

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal–derived slurry oil at 90 bar initial pressure for temperatures of 380–460^° C and residence time of 15–60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂–pressure of 60–150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂–pressure of 90–150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂–pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

Catalytic processing of atmospheric residue of petroleum over AlSBA-15 nanomaterials with different acidity

The AlSBA-15 nanomaterials with different Si/Al ratios were investigated as a promising material for processing of atmospheric residue of petroleum (ATR). The processing was performed in a thermobalance using nitrogen as a carrier gas at different heating hates. The catalytic pyrolysis was performed with ATR sample containing 20% mass of AlSBA-15. Based on TG data by applying Ozawa-Flynn-Wall kinetic model, the activation energy for the pyrolysis of ATR was higher than for the ATR/AlSBA-15, throughout all range of decomposition, indicating that the nanostructured material is a promising material for processing petroleum residues in order to obtain liquid products in the gasoline and diesel range.     

Desulfurization of high sulfur petroleum coke by molten caustic leaching

Desulfurization by molten caustic leaching (MCL) at 400–500 °C has been investigated in order to reduce the sulfur content of petroleum coke. Effective parameters on desulfurization of petroleum coke, other than temperature, include alkali to feed (petroleum coke) mass ratio, time and mesh size in the ranges of 0.5–1.5, 1–3 h and 200–600 µm, respectively. In this work, petroleum coke desulfurization conditions using solid KOH have been studied. Maximum petroleum coke desulfurization by MCL method has been obtained by Taguchi L9 design using alkali to feed mass ratio of 1, temperature of 600 °C, time of 2 h and mesh size of 200 µm. The changes in the main groups on the coke surface have been determined using FTIR spectroscopy. In addition, SEM-EDX, TGA and XRD analyses have been used to investigate the changes in coke physical and chemical properties.     

Reaction behavior of oil sand in fluidized-bed pyrolysis

The reaction behavior of oil sand from Inner Mongolia（China） were studied in a fluidizedbed pyrolysis process,and a comparative study was conducted on the properties of the liquid products obtained through fluidized-bed pyrolysis of oil sand and the native bitumen obtained by solvent extraction.The results indicated that the fluidized-bed pyrolysis,a feasible carbon rejection process,can be used to upgrade oil sand.The reaction temperature and time were found to be the key operating parameters affecting the product distribution and yields in fluidized-bed pyrolysis of oil sand.The optimal temperature was 490℃ and the most suitable reaction time was 5 min.Under these operation conditions,the maximum yield of liquid product was 80wt%.In addition,the pyrolysis kinetics of oil sand at different heating rates of 5,10,20 and 30℃/min was investigated using a thermogravimetric analyzer（TGA）.     

Catalytic Dewaxing for Lube Oil Production

Abstract

The selective cracking of long-chain normal paraffin's of medium neutral raffinate, derived from a lube oil-phenol extraction unit, by the catalytic dewaxing technique over H-ZSM-5 and NiMo-H-mordenite catalysts was studied. The runs were conducted to produce lube oils with acceptable cold flow properties. The influences of zeolite types, metals loading, and operating reactor temperatures (290°C–475°C) can have a great effect on cracking high pour point n-paraffins into lower ones, and hence a reduction in pour points. An increase in temperature (between 290°C and 375°C) increased wax conversion (percent dewaxing) on H-ZSM-5 compared with NiMo-H-mordenite catalysts due to its higher cracking activity. As a result, large amounts of C₁-C₄ gases and C₅-170°C naphtha were produced. The low pour point lube oils produced from catalytic dewaxing over H-ZSM-5 compared with NiMo-H-mordenite catalyst indicates that the former was more selective for removing wax components than the later. On the other hand, high concentrations of aromatics were obtained on both catalysts, since the waxy paraffins are converted to lower boiling products. The reduction in dewaxed pour points (Δpp) was observed to be in the range of 38°C–42°C over H-ZSM-5, compared to 37°C–40°C over NiMo-H-mordenite at the same reaction temperature ranges (290°C–375°C), but NiMo-H-mordenite has advantages at higher temperature ranges (above 375°C) in pour point reduction (Δpp range: 41°C–42.5°C). The addition of bimetallic components to the mordenite-catalyst enhances its activity, and the rate of normal paraffin cracking was increased due to the hydrogenolysis activity of the active metals. This means that the bimetallic H-mordenite catalyst has the advantage over H-ZSM-5 in its refining activities (hydrodesulfurization [HDS] and hydrodenitrogenation [HDN]) under the tested operating conditions. These results may be attributed to shape-selective discriminating behavior due to differences in zeolite pore openings (i.e., 6.5 × 7.0 Å for mordenite and 5.3 × 5.6 Å for ZSM-5). In other words, a combination of isomerization and selective cracking reactions of high n-paraffins may occur during the dewaxing process using NiMo-H-mordenite catalyst. The influences of process parameters (temperature, pressure, and liquid hourly space velocity [LHSV]) on the relations between wax conversion to maintain maximum low pour points and maximum dewaxed oil yields or minimum yields of the least desired gases were optimized to produce dewaxed lube oils of acceptable characteristics.     

低成熟度页岩油加热改质热解动力学及地层渗透性

低成熟度页岩油加热改质是采用加热井对地层进行加热，将地层中滞留的重质烃转化为轻质烃，同时将尚未转化的固体有机质热解生成油气后采出。热解油气生成量预测及地层孔渗变化是页岩油改质开采研究的难点和挑战之一。利用页岩井下取心样品，采用黄金管实验装置，研究了页岩加热过程中的有机质热解规律及组分动力学，获得了烃类气体、轻质油及重质油的生成动力学参数。结果表明，在温度为280~500℃范围内，油的生成量先增后减，而气体量持续增加；低速升温条件下的转化率随温度变化曲线左移，热解温度变低。重质油、轻质油和气态烃的活化能分别为39~49，57~74和56~59 kcal/mol；动力学模型可预测任意时间的烃类生成量。应用三轴高温渗透率测试装置，获得了页岩从室温到高温（550℃）条件下的氮气测试渗透率动态变化规律。结果显示，页岩加热过程中的渗透性变化分为下降段、上升段和稳定段，在温度达到有机质热解温度后，基质及裂缝渗透率均出现明显改善，比初始渗透率提高1~2个数量级。热解油气生成量及渗透率变化可为低成熟度页岩油加热改质开采的产量预测提供依据。     

A detailed model for combustion characteristics of petroleum residue and heat transfer coefficients in a CFB combustor

The authors developed a mathematical model for predicting the combustion characteristics of petroleum residue in a circulating fluidized bed at various conditions. It is a 1D unsteady state model that can be predicted the char conversion, output temperature, and heat transfer coefficients. Results showed that the heating rate plays a major role in the process; higher heating rate causes higher output temperature and heat transfer coefficient. It also found that the oxygen ratio has a positive influence on the char conversion and heat transfer coefficients. The model was validated against experimental data available in the literature and found to be in good agreements.     

1,3,3-trinitroazetidine (TNAZ). Study of thermal behaviour. Part II

Abstract

Thermal behavior of TNAZ (1,3,3 - trinitroazetidine) was studied by using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetryc analysis (TGA).

It was found out that TNAZ is thermally more stable than RDX, but less stable than HMX and TNT. The reaction of intensive thermal decomposition starts at 183–230 °C, depending on heating rate, while the first exothermic reaction was observed at 178 °C at the heating rate of 1 °C/min.

By applying multiple heating rate DSC measurements and Ozawa's method the activation energy of 161.3 kJ/mol and pre-exponential factor of 8.27·10¹³ 1/s were calculated from DSC peak maximum temperature-heating rate relationship. By the same method the activation energy of 157.5 kJ/mol and pre-exponential factor of 4.55·10¹³ 1/s were calculated from DTA peak maximum temperature.

By applying Flynn-Wall isoconversional method it was calculated from DSC measurements that the activation energy equals between 140 and 155.6 kJ/mol at degrees of conversion ranging between 0.3 and 0.7, while pre-exponential factor ranges between 7.8·10¹² and 1.92·10¹³ 1/s.     

The use of nonylphenol formaldehyde resins for preventing asphaltene precipitation in vacuum residues and hydroprocessed petroleum samples

This work focused on the synthesis and characterization of nonylphenol formaldehyde resins (NPFR) as examples of active molecules for preventing asphaltene precipitation in vacuum residue (VR) and hydroprocessed petroleum samples. The evaluation for the NPFR as asphaltene dispersants was carried out using the on-column filtration technique at room temperature and near process conditions (195°C). The results indicated that NPFR (molecular weight = 900–4800 Da) are active for the reduction of asphaltene content of gravimetrically separated asphaltene solutions and for VR and hydroprocessed samples at room temperature (35°C) and at 195°C. It was found that the activity of NPFR as asphaltene dispersants depends not only on the type of sample (asphaltenes, virgin or processed) but also on the temperature, molecular weight, and concentration.     

Silicone bridged iron metallocene butadiene composite solid propellant binder: aspects of thermal decomposition kinetics,pyrolysis and propellant burning rate

Propellant binders are essential components of composite solid propellants (CSP’s) used in launch vehicles and missiles. Binders act as a fuel and contribute directly to the combustion in conjunction with oxidizer particles and metallic fuel apart from imparting structural integrity to the solid propellant grain .The performance of CSP’s are directly related to the burn rate of the propellant. The burn rates of the ammonium perchlorate (AP) propellants are generally moderated using various types of transition metal oxide (TMO) catalysts. However, TMO’s are associated with inherently large dispersions in propellant burn rates and compromise on energetics. One of the most suitable methods for achieving lower dispersion in burn rate is using binders wherein a burn rate catalyst is grafted to the polymer matrix. In the present paper, the thermal decomposition of ferrocene bound hydroxyl terminated polybutadiene (FC-Si-HTPB) grafted to butadiene backbone via hydrosilylation was investigated The thermal degradation mechanism, stability and its effectiveness as burn rate catalyst are the most important aspects for use in CSP’s. The mechanism of decomposition of the neat resin and in combination with AP has been elucidated using pyrolysis gas chromatography–mass spectrometric technique (GC-MS). FC-Si-HTPB exhibits single stage decomposition in the temperature range of 263–491°C. The decomposition of FC-Si-HTPB with AP oxidizer follows a two stage mechanism in the 195–490°C.The char residue was characterized using FTIR, Raman spectroscopy and FE-SEM analysis, which enables to vindicate the mechanism of reaction. The activation energy for the decomposition of HTPB is 283.6 kJ/mol, FC-Si-HTPB is 251.5 kJ/mol and for Fc-Si-HTPB-AP system is 67.1 kJ/mol. The major pyrolysis products of neat FC-Si-HTPB are ferrocenyl derivatives, silylated ferrocenyl derivatives and precursors emanating from polybutadiene backbone. The propellants based on the new binder exhibited an increase in burn rate with iron content and higher fine content. A comparison of propellant burn rate with conventional micron sized ferric oxide exhibited an improvement of 34%.Based on the thermal analysis studies, the thermal endurance of the system was computed to be FC-HTPB> HTPB> FC-HTPB-AP.