Thermal Hydrocracking Kinetics of Chinese Gudao Vacuum Residue

Abstract

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.     

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.     

Direct construction of predictive models for describing growth of Salmonella Enteritidis in liquid eggs – A one-step approach

The objective of this study was to develop a new approach using a one-step approach to directly construct predictive models for describing the growth of Salmonella Enteritidis (SE) in liquid egg white (LEW) and egg yolk (LEY). A five-strain cocktail of SE, induced to resist rifampicin at 100 mg/L, was used to inoculate LEW and LEY. Kinetic studies were conducted isothermally at different temperatures between 8 and 43 °C to generate growth curves at each temperature.This study first solved an inverse problem globally, using the growth curves to estimate the temperature-dependent kinetic parameters, and then applied the parameters to predict growth (a forward problem). Once the growth curves were generated, they were assembled and analyzed using nonlinear regression to determine kinetic parameters of both primary and secondary models in one step, with an objective to minimize the global residual sum of squares (RSS) for the entire data set. For growth in LEW, a three-parameter logistic model was used. For growth in LEY, the Huang model was used as the primary model. The Ratkowsky square-root model was used to evaluate the growth rates.The results showed that the one-step approach resulted in accurate estimation of the kinetic parameters that were used later to successfully predict the growth of SE in LEY and LEW. The estimated nominal minimum growth temperatures of SE were 7.4 °C and 9.9 °C, while the estimated maximum growth temperatures were 45.2 °C and 46.8 °C, respectively, in LEW and LEY. As a validation, the predictive models were tested with independent growth curves of SE in LEY and LEW at 37 °C. The root mean square error (RMSE) was only 0.36 and 0.28 log CFU/ml over a total scale of 8.4 and 7.8 log CFU/ml, respectively, for the growth models of SE in LEY and LEW, suggesting that the one-step approach can generate accurate models for predicting the growth of SE in LEY and LEW. The results from this study can be used to predict the growth of SE and evaluate the safety of LEY and LEW.     

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.     

Mechanism of the inhibiting effect of diphenylamine in the oxidation of hydraulic oils

The mechanism of the inhibiting effect of diphenylamine during the oxidation of two base stocks of hydraulic oils were studied at 120, 130, and 140°C. The key reactions in the mechanism of the action of the inhibitor were identified, and the values of the kinetic parameters and their activation energies were determined. The kinetic parameters were calculated, and the salient kinetic features of the inhibited oxidation of the two specimens were compared at 70°C, the temperature of accelerated testing of hydraulic oils. The results of this prediction were analyzed, and the reasons for differences in the oxidation stability of the samples examined were established.     

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.     

THERMAL EFFECT ON THE PERMANENT VISCOSITY OF A SASKATCHEWAN HEAVY OIL

ABSTRACT

Future energy demands will likely cause increased activity towards the recovery of heavy oil using non-conventional means. Most non-conventional attempts to recover Saskatchewan's heavy oil resources have utilized thermal techniques.

This report discusses the permanent viscosity changes which occur when heavy oil.is subjected to thermal processes from 220 to 425°C. It was observed that under closed operating conditions, the oil viscosity drops in a manner which can be modeled by a first order, kinetic reaction model. The rate constant for this reaction varied from 0.3 × 10^?3 to 6.0 × 10^?3 h^?1 depending on temperature and the assumed molecular weights of the model components. These findings closely parallel earlier results.

Experimental observations on thermal effects during opened operating conditions indicate a dramatic and rapid rise In the remaining crude oil viscosity. The oil was observed to increase its permanent absolute viscosity by a factor as high as 21 times its original absolute viscosity. The single product, first order kinetic model was not capable of predicting this rise in oil viscosity. A simple, two product, first order kinetic model was developed and found to fit the data satisfactorily with a rate constant of 0.6 h^?1 for heavy product formation and a rate constant of 0.03?h^?1 for light product formation at 275°C.     

Characterization of Thermally Degraded Asphaltene Fractions Using Gel Permeation Chromatography

Abstract

Petroleum asphaltene goes through three stages of mass reduction under thermogravimetric analysis from 25°C to 1,000°C at a heating rate of 1°C/min. The products from thermal degradation of asphaltene at three different temperature intervals are collected. Two residual fractions left in the sample cup are also obtained at two specific temperatures. The collected fractions and the residual fractions are characterized using gel permeation chromatography. The fraction collected between 25°C and 350°C demonstrates similar molecular weight distribution to that collected between 350°C and 450°C, with both fractions showing a typical molecular weight distribution for polymeric material. The fraction collected between 450°C and 650°C illustrates three different molecular weight distributions. The chromatogram of the residual fraction obtained at 350°C resembles that of the undegraded asphaltene. The residual fraction obtained at 450°C also demonstrates three different molecular weight distributions. The experimental data indicate that the mass reduction of asphaltene heated from 25°C to 350°C is mainly due to the evaporation of low boiling point and/or low molecular weight substances in asphaltene. Thermal decomposition and coke production occur significantly in the 350°C–450°C temperature interval. Thermal degradation continues to finish until 650°C.     

NON-ISOTHERMAL PYROLYSIS OF TWO KINDS OF CHINESE OIL SHALE

Abstract

Non-isothermal pyrolysis of two kinds of Fushun oil shale with particle sizes, <0·075 mm, 0·3 - 0·5 mm, 0·75 - 1·0 mm and 1·5 - 2·0 mm, has been investigated in stream (nitrogen) at the flow rate of 100 ml/min by thermo-gravimetric analyzer with a linear heating rate 6·8K/min. It has been found that the temperaturee intervals of oil-generation from rich grade shale ( 9·8 % Fisher Assay oil yield ) and poor grade shale ( 3·9% Fisher Assay oil yield ) with particle size less than 2·0 mm are 400 - 500 °C and 400 - 520° C respectively. The kinetic treatment of the thermo gravimetric data reveals that pyrolytic reactions of the two kinds of Fushun oil shale are both of the first order, but with different activation energy E and pre-exponential factor A in different temperaturee regions during pyrolysis. This is different from what was described in general terms as global first order reaction for oil shale pyrolysis by other anthers. The kinetic parameters for pyrolysis of the two kinds of Fushun oil shale with different particle sizes were calculated by means of least square curve fitting, and the influence of particle size on pyrolysis was also discussed.     

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.     

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.     

Dynamic analysis of growth of Salmonella Enteritidis in liquid egg whites

Salmonella Enteritidis (SE) is a common foodborne pathogen associated with eggs and egg products. This research was conducted to study the kinetics of growth and survival of SE in liquid egg whites (LEW). A dynamic temperature profile that exposed SE to suboptimal temperatures and below the minimum growth temperature (T_min) was used with two isothermal conditions to develop kinetic models. One-step dynamic analysis was used to directly construct a tertiary model for describing the growth and survival of SE and determine the kinetic parameters.The results of kinetic analysis showed that the T_min was 7.7 °C and SE may die off at a rate of 2.78 × 10⁻³ log CFU/ml per h per °C below the T_min. The root mean square error (RMSE) of the model was 0.5 log CFU/ml, with 76.6% of the residual errors within ±0.5 log CFU/ml of the experimental observations. The model was validated under both dynamic temperature and isothermal conditions. Both growth and survival of SE was accurately predicted, with the RMSE of validation at < 0.5 log CFU/ml. For all the validation tests, nearly 75% of the residual errors were within ±0.5 log CFU/ml of the experimental observations.This study clearly demonstrated that the one-step dynamic analysis method is an accurate and efficient method for direct construction of predictive models and estimation of the associated kinetic parameters that govern the growth and survival of microorganisms in food. Since the mathematical model has been validated, it can be used to predict the growth and survival of SE in LEW during storage and distribution and for conducting risk assessment of this microorganism.     

Thermolysis of 2-[4-(chloro-<Emphasis Type="Italic">tert</Emphasis>-butyl)phenyl]propan-2-yl hydroperoxide: Kinetics and mechanism

The kinetic features and products of the thermolysis of 2-[4-(chloro-tert-butyl)phenyl]propan-2-yl hydroperoxide in the temperature range 120–190°C have been studied. The mechanism of the process is discussed.     

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.     

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.     

Effect of hydrogenation on the oxidation resistance of decene oligomers

The kinetics of autoxidation and initiated oxidation of PAO-2, PAO-4, PAO-6, and PAO-10⁺ decene oligomer fractions at 140°C after a hydrogenation process was studied. Key reactions in the mechanism of oxidation were identified; the numerical values of the kinetic parameters were determined, and mathematical models, which quantitatively described the experimental data on the consumption of oxygen and the buildup of hydroperoxides during the course of the oxidation of the test samples, were obtained. The oxidation resistances of hydrogenated fractions were compared with each other. It was found that the kinetic parameters of the test samples were similar, and the oxidation of all of the hydrogenated oligomers occurred by approximately the same processes. Using the PAO-2 fraction at 120, 130, and 140°C as an example, the oxidizability of hydrogenated and unhydrogenated samples was compared. It was found that hydrogenation improved all of the kinetic characteristics and, consequently, increased the oxidation resistance of oligomers. However, the oligomers remained readily oxidizable substances, particularly, at elevated temperatures.     

Kinetic Modeling of MTO Process Applying ZSM-5 Zeolite Modified With Phosphorus as the Reaction Catalyst

In the present study, a number of phosphorus modified HZSM-5(Si/Al = 250) zeolite as MTO catalyst were prepared and characterized by various methods. A kinetic model for MTO process over PZSM-5 catalyst was developed based on data obtained from a differential fixed bed reactor within the temperature range of 360–425°C and 1 bar pressure applying the Langmuir-Hinshelwood formulation. The kinetic parameters were evaluated from the experimental data using genetic algorithm. It was found that the predicted data from the model were well correlated with the experimental results, indicating that ethylene and propylene are primary olefins.     

Thermoluminescence parameters and kinetics of irradiated inorganic dust collected from black peppers

Irradiated foods can be detected by thermoluminescence (TL) of contaminating inorganic dust particles. In this study, black peppers were irradiated with gamma rays at doses of 1, 3, 5 and 10 kGy. The inorganic dust particles collected from irradiated black pepper are investigated. This study reports the mineral composition of this dust being, mainly quartz, feldspar and little amount clay minerals. The TL detection method is clearly able to distinguish irradiated and non-irradiated black peppers at the doses ranging from 1 to 10 kGy. The paper provides a detailed calculation of the activation energy (E), frequency factor (s) and the order of kinetics of the 240 °C TL identification peak in polymineral dust material. The experimental and computerized deconvolution results are consistent with the presence of a closely overlapping second-order TL peaks in the identification peak at 240 °C. The TL kinetic parameters of overlapping peaks were estimated by computerized deconvolution method. The computer deconvolution shows the existence of four well-defined TL peaks at 118, 210, 270 and 305 °C. These four peaks probably due to the combined TL of quartz and feldspar minerals.     

Determination of thermal inactivation kinetics of Listeria monocytogenes in chicken meats by isothermal and dynamic methods

The objective of this research is to determine the thermal inactivation kinetics of Listeria monocytogenes in chicken breast meat under both isothermal and dynamic conditions. A four-strain cocktail of L. monocytogenes was inoculated to chicken breast meat. Isothermal studies were performed by submerging samples under hot water maintained at constant temperatures ranging from 54 to 66 °C. The D values at each temperature were determined and used to calculate the z value, using log(D) = log(D₀) − T/z. Dynamic studies were conducted by submerging samples in a water bath with its temperature programmed to increase linearly from 30 to 65 °C at 1.25 °C/min or 1.73 °C/min. A method was developed to determine the kinetic parameters from linear heating temperature profiles.The thermal inactivation of L. monocytogenes in chicken breast meat followed the first-order kinetics. The z value determined from the isothermal studies was 4.95 °C, which is very close to the values reported in the literature. The dynamic method can also be used to determine the thermal inactivation kinetics of L. monocytogenes. The average z value (4.10 °C) determined by the dynamic method was slightly lower than that determined by the isothermal method. However, the parameters (D₀ and z) determined from both isothermal and dynamic methods can be used to estimate the survival of L. monocytogenes exposed to linear heating temperature profiles, with statistically equal accuracies.The dynamic method explored in this study can be used to determine the D₀ and z values of microorganisms that exhibit first-order kinetics and are exposed to linear heating temperature profiles. Compared to the isothermal method, the dynamic method requires few data points and is equally accurate.     

Kinetics of ochratoxin A destruction during coffee roasting

In the present study, Coffea arabica was artificially contaminated with spores of toxigenic Aspergillus westerdijkiae. The contaminated coffee was roasted in a vertical spouted bed roaster at four different temperatures (180 °C, 200 °C, 220 °C and 240 °C) and three different time periods (5, 8 and 12 min), in order to obtain more accurate results for the development of the kinetic model for ochratoxin A (OTA). Chlorogenic acids (CGA) content during coffee roasting was also evaluated to investigate the effect of the heat employed to destroy OTA in these health promoting compounds. Coffee treated with spouted bed roasting significantly reduced the OTA level from 8% to 98%. The spouted bed roasting proved to be a very efficient procedure for OTA reduction in coffee, and its reduction depended directly on the degree of roasting. OTA degradation during coffee roasting followed first order reaction kinetics. Using the apparent activation energy of OTA degradation and the temperature-dependent reaction rate, there was a compliance with the Arrhenius equation. This model was capable of predicting the thermal induced degradation of OTA and may become an important predicting tool in the coffee industry. The present study was also able to propose roasting conditions appropriate to destroy OTA and maintain most of the CGA at the same time.