Thermal Hydrocracking Kinetics of Chinese Gudao Vacuum Residue

The thermal hydrocracking kinetics of Chinese Gudao vacuum residue was studied in a batch autoclave reactor. The temperature ranged in 390-435°C and the initial hydrogen pressure was 7.0 MPa at 20°C. Ammonium phosphomolybdate (APM) in its dispersed phase was the catalyst. The reaction products, gas, naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO) and coke, were separated during and after experiments, and their yields vs. reaction time were obtained, for four reaction temperatures: 390, 405, 420, and 435°C. The activation energy was calculated from a traditional kinetic model to be 218.6 kJ/mol. A new kinetic model was proposed in this work that allows for the calculation of activation energy with a minimum number of three tests, each at a different temperature. This is comparable to the traditional model which requires a minimum of 12 tests; a minimum of four tests for one temperature and a minimum of three temperatures. The activation energy calculated from the new model with four tests is 229.6 kJ/mol, only 5% greater than that obtained from the traditional model. The reaction rate constants obtained from this model are also consistent with those from the traditional model.     

Analysis of the thermal hydrocracking of heavy fuel oil

The thermal hydrocracking of Mexican heavy fuel oil was studied at 1200 psia and different reaction temperatures (370, 380, 390 and 400°C). The results show that the vacuum residue which constitutes 62 wt. % of the heavy fuel oil and contains 47 wt. % resins and 23.3 wt. % asphaltenes, reacts to form lighter hydrocarbons (IBP-540°C), solid and gas. Resins transform more easily to saturates, and gases are produced mainly from the asphaltene fraction, indicating that the terminal alkyl groups in this fraction are shorter than those present in the resin fraction. The C-C scission reactions dominate the transformation of heavy fuel oil in the interval from 370 to 390°C, whereas the carbon rejection reactions are dominant at 400°C. Finally, the thermal hydrocracking of heavy fuel oil at 390°C appears suitable since at this temperature the reaction produces the greater amount of atmospheric distillates (+20.5 wt. %) and a low content of solid (2.0 wt. %) and gas (2.1 wt. %).     

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。     

Kinetic Modeling of Hydrodesulphurization of Residual Oils. I. Power Law Model

Abstract

The kinetics of hydrodesulphurization (HDS) reaction of residual oils at temperatures of 320–440°C has been explored leading to the development of a power law model. The reaction order was found to decrease with increasing temperature from 4.33 to 1.42 while the rate constant increased with temperature from 0.312 to 10.847 kg/mol h. The activation energy of 101.0 kJ/mol and a frequency factor of 3.42 × 10⁸ were also recorded. These results are in excellent agreement with other work reported in the literature. The study also revealed the sharp contrast between HDS and Sulphurization, which has its reaction order increasing with temperature.     

Kinetics of the thermal decomposition of acid tar

It has been shown that the reaction rate of the thermal decomposition of acid tar containing sulfoacids obeys the equation of the first order reaction. Two temperature ranges of thermal decomposition have been detected. The processes of the liquid phase transformation of the components of the reaction mixture dominate in the low temperature range (200–360°C, apparent activation energy E = 37 kJ/mol), and gas-phase reactions dominate in the high temperature range (390–500°C, E = 106 kJ/mol). Sulfuric acid, additionally introduced into acid tar, participates in redox reactions, resulting in the rapid formation of sulfur(IV) oxides and benzene.     

Thermal and catalytic pyrolysis of vacuum gas oil using HZSM-5: TG and PY-CG/MS study

The zeolite HZSM-5, was synthesized in the absence of an organic template. The characterization of zeolite HZSM-5 was performed by X-ray diffraction, N₂ adsorption/desorption isotherms and scanning electron microscopy. For catalytic tests, applying the free kinetic model, it was observed that the activation energy for the pyrolysis of pure VGO was of 82 kJ mol^?1 and for VGO/HZSM-5, the value decreased to approximately 60 kJ mol^?1, demonstrating the effectiveness of the acid sites effect of zeolite ZSM-5 for the VGO pyrolysis resulting in production of gas, gasoline and diesel.     

A kinetic model for pyrolysis of petroleum residue under nonisothermal conditions

Kinetic study on pyrolysis of petroleum residue was carried out by an accurate Arrhenius type equation at heating rate of 0.5–30.0°C/min under nonisothermal conditions. The influence of some critical parameters including temperature, heating rate and activation energy on mass conversion was evaluated. The apparent activation energies for during the pyrolysis process were in the range of 198–361 kJ/mol at various mass conversions of 5–94%. The reaction temperature was introduced as the most important parameter for the improvement of mass conversion, compared to that of other parameters. The pyrolysis of petroleum residue was occurred in a broad temperature range, from 150–650°C, yielding 33 wt% unpyrolyzed residue. It also was found that an increase in heating rate has a minor impact in the process. Model predictions were compared with experimental data, which showed fully good agreement.     

Application of a Continuous Kinetic Model for the Hydrocracking of Vacuum Gas Oil

Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and predicted product distributions indicated that the model was successful in predicting the products from hydrocracking reactions.     

Energy and exergy assessments of dehydrogenation of propane for propene production

The energy and exergy assessments of the dehydrogenation of propane for propene production process were performed. The results show that when the reaction temperature rises from 400°C to 1000°C, the range of inlet and outlet exergy is 2268～2376 and 2265～2341 kJ/mol C₃H₆, respectively, and the range of exergy destruction is 6.31～33.24, 9.93～35.15 and 3.59～31.99 kJ/mol C₃H₆ at 5, 25 and 45°C reference environment temperature, respectively. The range of exergy efficiency at discussed reference environment and reaction temperature is 98.52～99.84%, and decreases with the increasing of reaction temperature and increases with the decreasing of reference environment.     

羰化-氢解法低温合成甲醇 Ⅴ.催化反应宏观动力学研究

采用磁传动搅拌反应器 ,对使用自制的铜铬氧化物甲醇合成催化剂的低压宏观反应动力学特性进行了实验研究。采用幂律法对实验数据进行处理 ,建立了催化剂的宏观反应动力学方程。在 35 3～ 393K温度范围内 ,催化反应的活化能为 6 7 0kJ/mol,这一数值与甲醇羰化制甲酸甲酯的活化能相近     

Cracking of Maya Crude Asphaltenes

Cracking of Maya crude asphaltenes was carried out in a batch reactor at the following reaction conditions: temperature of 380–410°C, total pressure of 2 MPa, and asphaltenes/catalyst ratio of 5 g/g using NiMo commercial catalyst. n-hexadecane was used to keep asphaltenes dispersed and reaction time ranged from 0 to 60 min. The products were lumped into four fractions: asphaltenes, maltenes, gases, and coke. A kinetic model assuming pseudo–first-order parallel reactions was used to fit the experimental data.     

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.     

Preparation of furfural and reaction kinetics of xylose dehydration to furfural in high-temperature water

Factors influencing dehydration of xylose to furfural,such as catalyst and extract agents,were investigated.Results indicated that high-temperature water may substitute for solid and liquid acid as a catalyst,and ethyl butyrate improved furfural yield for the high distribution coefficient.A furfural yield of 75 % was obtained at200 °C for 3 h in ethyl butyrate/water.The reaction kinetics of xylose dehydration to furfural was investigated and it was found that the reaction order was 0.5,and the activation energy was 68.5 k J/mol.The rate constant k showed a clear agreement with the Arrhenius law from160 to 200 °C.     

STUDY ON COKING KINETICS OF CHINESE GUDAO VACUUM RESIDUE

ABSTRACT

Using a molten metal bath as heat source of reaction, the coking kinetics of Gudao vacuum residue in temperature ranges of 400 – 440°C and 460–500°C were studied and kinetic models were developed. The order of reaction, pre-frequency factor and apparent activation energy of thermal-cracking were determined as 1.0, 7.853 × 10¹⁰ min^?1 and 175.3KJ/mol respectively. The results laid a solid foundation for technological computation, reconstruction and design of the tubular furnace using the residuum as its feedstock.     

减压蜡油浆态床加氢工艺条件和动力学研究

对减压蜡油的浆态床加氢工艺条件进行了评价,并考察了减压蜡油的加氢脱硫和加氢脱氮动力学。研究结果表明,最佳的蜡油加氢工艺条件为反应温度360 oC、反应压力8 MPa、催化剂加入量（w）9 %、反应时间2 h左右。动力学研究结果表明：对于加氢脱硫反应,反应初期的表观活化能为100.44 kJ/mol;反应中期到末期,表观活化能为121.72 kJ/mol,这是由于不同类型的硫化物脱硫机理不同造成的;对于加氢脱氮反应,表观活化能为105.17 kJ/mol;在反应初期含氮化合物较难脱除,而在反应后期,烷基取代的二苯并噻吩类化合物为最难脱除的化合物。     

Application of a Fluidized Bed Reactor in the MTO (Methanol to Olefin) Process: Preparation of Catalyst and Presentation of a Kinetic Model

Abstract

Light olefins are basic raw materials for petrochemical industries and the global demand for the latter is growing. The authors investigated the conversion of methanol to light olefins in presence of acidic SAPO-34 molecular sieve as the reaction catalyst. SAPO-34 was synthesized by hydrothermal method, applying morpholine as the template. The molecular sieve was then changed into protonated form by ion exchange process with ammonium chloride at 80°C. A kinetic study was carried out within the temperature range of 375–425°C and 4 bar pressure using a differential fixed bed reactor. An appropriate kinetic model was presented and the kinetic parameters were evaluated as functions of temperature. In addition, the formation of light olefins was implemented in a fluidized bed reactor under a wide range of operating conditions. The experimental results were correlated with those predicted from a hydrodynamic model. Taguchi's experimental design method was applied to determine the optimum operating parameters of this process conducted in the fluidized bed reactor. The optimized parameters were the following: temperature = 425°C; ratio of inlet gas velocity to minimum fluidizing velocity (U₀/U_mf) = 7; catalyst mean particle size = 240 μm.     

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.     

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.     

Physical mixture of MCM-41/ZSM-5 as an active catalyst component for maximization of propylene in Catalytic cracking of VGO

The performance of a novel catalyst additive containing highly porous MCM-41 and ZSM-5 zeolite was investigated using a commercial equilibrium FCC catalyst in catalytic cracking of vacuum gas oil. The catalytic tests were assessed in a fixed-bed microactivity test unit at reaction temperatures 500–620 °C. The highest propylene yield of 23.8 wt% was achieved at 600 °C. The propylene yield increased from 14.49 wt% to 23.8 wt% when the temperature rose from 500 to 600 °C; however the gasoline yield fell from 22.47wt% to 16.49 wt% by increasing the temperature from 580 °C to 620 °C, respectively.     

A kinetic model for delayed coking process of Iranian vacuum residues

A four-lump kinetic model was developed for delayed coking process of Iranian vacuum residues. The feedstock and products were considered as a unique and three separated lumps, respectively, in the model. The product lumps were included gas (C₁–C₄), distillate (C₅₊ –500?°C), and coke (toluene insoluble and 500?°C+). The reactions performed in an atmospheric batch pilot plant reactor by selected feeds at three temperatures (420, 450, and 480?°C) and four residence times (10, 30, 50, and 120?min). Reactions were assumed in first order and based on Arrhenius reaction rates. Also, the kinetic model was validated by a similar feed at different conditions that showed suitable precision with experimental results.