Phenomenological thermokinetic analysis of coffee husk pyrolysis: a study case

Journal of Thermal Analysis and Calorimetry - The thermokinetic analysis of the pyrolytic degradation of coffee husk reveals that the degradation path of its main pseudo-components at the maximum...     

Gas-liquid chromatographic determination of the gaseous products of the two-stage pyrolysis of heavy oils

The two-stage pyrolysis of fuel oil and vacuum residues separated from Egyptian crude oil have been carried out using a batch-type reactor technique. In the first stage, feedstocks undergo catalytic cracking in the presence of platinum as a catalyst at temperatures ranging between 380 and 460 °C and 440 and 520 °C for fuel oil and vacuum residues, respectively. Products are carried by argon gas for subsequent pyrolysis in the second stage at temperatures ranging between 700 and 820 °C and 700 and 800 °C for fuel oil and vacuum residues, respectively. The gas yields are about 94.1 and 82.0 wt% of the total products. The gases comprise saturated (C₁----C₅) and unsaturated hydrocarbons (ethylene, propylene, and butenes). By using platinum wire in the pyrolysis of fuel oil, the ethylene yield increases slightly as the temperature of the first stage increases, while it remains almost unchanged in the pyrolysis of vacuum residue. On the other hand, the propylene yield decreases slightly as the temperature of the first stage increases in the two feedstocks. By using a platinum sheet, the ethylene yield is doubled under the same conditions and increases slightly with an increase of temperature in the second stage. On the other hand, the propylene yield varies inversely with the temperature of the second stage by using platinum, whether as wire or sheet, although the yield is higher when platinum sheet is used under the same conditions.     

Detoxification of brominated pyrolysis oils

The development of an innovative technology for the pyrolytic conversion of brominated phenols in a reductive medium aimed at product recovery for commercial use is discussed in this paper. Brominated phenols are toxic products, which contaminate pyrolysis oil of wastes from electronic and electrical equipment (WEEE). The pyrolysis experiments were carried out with 2,6-dibromophenol, tetrabromobisphenol A, WEEE pyrolysis oil and polypropylene or polyethylene in encapsulated ampoules under inert atmosphere in quasi-isothermal conditions (300–400 °C) with a different residence time (10–30 min). Optimal conditions were found to be the use of polypropylene at 350 °C with a residence time of 20 min. The main pyrolysis products were identified as HBr and phenol. A radical debromination mechanism for the pyrolytic destruction of brominated phenols is suggested.     

Thermodynamic and thermokinetic characterization of vitreous eutectic germanium-tellurium alloy by differential scanning calorimetry

For germanium-tellurium binary glass of eutectic composition heat capacities have been measured using differential scanning calorimetry. From these values enthalpy, entropy and corresponding configurational terms have been deduced, which agree closely with the “hole-theory”. Below the glass transition temperature, differences have been observed for the thermodynamic characteristics of vitreous and crystalline forms. For closely-related glasses kinetic parameters are more suitable for characterization than the above thermodynamic parameters. For germanium-tellurium alloys with small amounts of gold added, kinetics of devitrification have been expressed in terms of the crystallinity ratio. Values of Kgl parameters of glass-formation ability are also given (Kgl=0.478 for the eutectic composition alloy without gold).     

Kinetic study of heavy crude oils by thermal analysis

The present work investigates the thermal behavior and kinetic of four types of petroleum samples: a medium crude oil—P1, one heavy oil—P2, and two extra heavy oils—P3 and P4 by TG, DTG, and DSC methods. Thus, this study may contribute to the characterization of petroleum with different °API values.     

Biochemical processing of heavy oils and residuum

Applied Biochemistry and Biotechnology -     

镨配合物的热化学及其对酵母菌作用的热动力学研究

用六水合氯化镨、硫代脯氨酸(C4H7NO2S)和水杨酸(C7H6O3)合成了三元固体配合物[Pr(C7H5O3)2(C4H6NO2S)]-2H2O.根据盖斯定律设计一个热化学循环,用溶解-反应量热法研究得到合成反应的标准摩尔焓变为(133.70±1.02)kJ/mol,配合物298.15K时的标准摩尔生成焓为-(2909.3±3.2)kJ/mol.用TAMair微量热仪测定其在28.00℃时对粟酒裂殖酵母作用的产热曲线,进而算出在配合物作用下,酵母菌生长代谢的最大发热功率Pmax、速率常数κ、传代时间tG、抑制率I和半抑制浓度cI,50等热动力学参数.结果表明:稀土水杨酸硫代脯氨酸配合物在低浓度下对酵母菌有刺激作用,高浓度下为抑制作用,即稀土配合物对微生物的生长具有双向生物效应,也称为Hormesis效应.     

Thermogravimetric characterization of Quayarah heavy crude oils

Five heavy crude oil samples from the Quayarah field were thermally evaluated using two modes of thermogravimetry (TG): dynamic and programmed TG with heating and hold-up periods at 350 and 550°. The light and medium volatility fraction (L+M) appeared directly proportional to the metal content. In contrast, the heavy fraction (H) (350–550°) was inversely proportional to the metal content. This contradiction was attributed to the autocatalytic degradation of some of the heavy fraction into lighter species, which upgrades the crude with respect to the (L+M) fraction at the expense of the heavy fraction. The crudes were identical with regard to the ratio (L+M) to (H+R), whereR=residue, as a consequence of their identical API gravity and sulphur contents.The rate of degradative volatilization of the heavy fraction was measured by DTG, which indicated a direct correlation with the vanadium content as regards the onset temperatures and the DTG peak maximum.

---

Zusammenfassung Fünf vom Quayarah-Feld stammende schwere Rohöle wurden mittels dynamischer und programmierter TG mit konstanten Perioden bei 350 und 550 °C charakterisiert. Der Anteil der leicht- und mittelflüchtigen Fraktion (L+M) schien proportional, der der schwerflüchtigen Fraktion (H) (350 550°) dagegen umgekehrt proportional dem Metallgehalt zu sein. Dieser Widerspruch wurde dem autokatalytischen Abbau einiger der schwerflüchtigen Komponenten zu leichteren Spezies zugeschrieben, der zu einer Erhöhung des Anteils der (L+M)-Fraktion auf Kosten der schwerflüchtigen Fraktion führt. Die Rohöle waren wegen der gleichen API-Schwere und gleicher Schwcfclgehalle hinsichtlich des Verhältnisses von (L+M) zu (H+R) identisch (R=Rückstand). Die Geschwindigkeit der degradaliven Verflüchtigung der schweren Fraktion wurde mittels DTG gemessen, wobei sich eine direkte Korrelation zwischen dem Vanadingehalt einerseits und der Einsatztemperatur bzw. dem DTG-Peakmaximum andererseits ergab.

---

350 550°. (+ ) , () (350–550°) — . , . + +, — , . . , , .

     

Thermodynamic phase equilibria of wax precipitation in crude oils

Economic loss due to wax precipitation in oil exploitation and transportation has reached several billion dollars a year recently. Development of a model for better understanding of the process of wax precipitation is therefore very important to reduce the loss. In this paper, a new thermodynamic model for predicting phase equilibriums of crude oils is proposed. The modified SRK EOS and the UNIQUAC equations are used to describe the vapor, liquid phase and the wax, respectively. New correlations have been introduced to calculate the volume parameter, c, in SRK EOS and the heat of vaporization in UNIQUAC equation. The model can be used to describe the systems which contain paraffin, naphthene and aromatic fractions. New correlations for the enthalpies, temperatures of solid–solid transitions and fusion enthalpies of paraffins are established in this paper based on data obtained from open literature. By using the proposed modified model, the wax precipitation in hydrocarbon fluids has been predicted for three crude oil systems. The calculation results have been compared with experimental observations and those results obtained using regular solution models. It is found that wax precipitation in complex systems can be better predicted by using this new model.     

重金属对重油热转化过程生焦特性的影响

以委内瑞拉减渣、辽河减渣、克拉玛依减渣三种劣质减压渣油为原料,在微型反应釜中进行反应,研究重金属等因素对重油热转化过程生焦特性的影响。结果表明,重油中重金属含量越高,其在热转化过程中的生焦诱导期越短。随着重金属总含量的增加,重油的生焦量明显增多,生成的焦颗粒也逐渐变大。延迟焦化产物分析结果进一步表明,重金属含量越高的重油,焦产率越高,导致液体产物收率下降。     

Lignin derived oils from the fast pyrolysis of poplar wood

A pyrolysis oil obtained from the fast pyrolysis of poplar wood was subjected to mild hydrolysis and an aqueous and a non-aqueous fraction recovered. The non-aqueous fraction (pyrolytic lignin), a brown powder, was 23% of the oil, or 16% of the wood, corresponding to about 80% volatilization of the lignin content. Nuclear magnetic resonance spectra of this pyrolytic lignin were obtained, and its structure appears to be very similar to that of steam exploded poplar lignin. Methoxy content is relatively high and syringyl units appear to predominate over guaiacyl units. The pyrolytic lignin appears to be somewhat more degraded than steam exploded lignin and is probably lower in molecular weight.     

Study on the thermokinetic properties of bacterial growth

The power-time curves of bacterial growth at different temperatures were determined by using the 2277 Thermal Activity Monitor (Sweden). From these curves, the growth rate constant () and activation energy (E _a) were calculated. According to the transition state theory of reaction dynamics, the activation entropy (S), activation Gibbs free energy (G) and equilibrium constant (K ) of the activation state could be calculated. These results permitted thermodynamic analysis of the bacterial growth metabolism.Supported by the Natural Science Foundation of Shandong Province.     

自由基引发剂对重油加氢裂化的影响研究

在高压釜式反应器中考察了添加过氧化特二丁基(DTBP)、偶氮二异丁腈(AIBN)和单质碘(I2)三种自由基引发剂对克拉玛依蜡油、孤岛减压渣油加氢裂化反应的影响。在氢气初始压力7.0 MPa,反应1 h的条件下,对引发剂用量、催化剂用量、反应温度等影响因素进行了考察。结果表明,添加自由基引发剂后,重油的加氢裂化转化率,轻质油收率以及HDS、HDN都明显增加。添加质量分数5 000×10-6或10 000×10-6引发剂后,蜡油和减压渣油加氢裂化的轻质油收率最大可增加10%、13%,HDS和HDN最大可增加11%和7%左右。采用较少的催化剂用量或较低的反应温度即可以实现较高的重油转化率和轻质油收率。相对而言,DTBP和I2的促进作用优于AIBN。添加引发剂前后的加氢裂化的产物分布对比说明,引发剂的加入有利于蜡油或渣油原料一次裂化产物的生成。     

Fluidised bed pyrolysis of Moroccan oil shales using the hamburg pyrolysis process

In the present work, the pyrolysis of the Moroccan Timahdit oil shale was studied, using a fluidised bed process. Four experiments were carried out at different temperatures between 520 and 630 °C. By mass balance could be shown that in relation to the kerogen content up to 60 wt.% of oil and 25 wt.% of gas are obtained. These are 40% higher yields compared with the Fischer assay. It was shown that the carbon in the residue, which is much lower (only 12 wt.%) than in the Fischer assay (26 wt.%), explains this difference.     

Quality and limits of a thermokinetic method to study gas—solid interactions

In order to test the qualities and limits of a thermokinetic method for the determination of adsorption rates, the adsorption of separate doses of oxygen on an initially nearly stoichiometric nickel oxide was studied at 473 K by two independent methods: calorimetry and pressure measurements.The calorimetric curves were corrected for instrumental distortion and compared with the results based on pressure curves. The following aspects of the correction procedure are discussed: determination of the instrument response function, smoothing procedure, influence of the ratio of the velocities of the instrument response and of the reaction under study.     

Comparative study of crude oils from the Machete area in the Eastern Venezuelan Basin by pyrolysis of asphaltenes

This work is an analysis of crude oil samples from the two most recent producing wells in the Machete area (Orinoco Tar Belt, Venezuela). The aim is to determine the type of environment in which the precursor organic materials were deposited. In spite of the fact that the degree of maturity and the biodegradation of the two crude oils are similar, their characterization leads us to conclude that they have very distinctive and different origins. The comparative study was performed by separating their main fractions, pyrolysis of asphaltenes, and further identification of several indicators (aromatic, polar and sulfur compounds, linear aliphatic hydrocarbons, and cadalene). Moreover, several biomarkers (terpanes, hopanoids and steranes) present in the saturated fractions obtained from the two crude oils were analyzed by using gas chromatography combined with mass spectrometry (GC–MS). The statistical study of geochemical indicator values and relative proportions of lipid and lipid-like biomarkers present in products from asphaltene pyrolysis shows a high probability of there being two distinct crude oil families from the Machete area.