Min Heating Rate Research Articles

Thermogravimetric Kinetics of Catalytic and Non-Catalytic Pyrolytic Conversion of Palm Kernel Shell with Acid-Treated Coal Bottom Ash

The catalytic and non-catalytic pyrolytic conversion kinetics of palm kernel shell (PKS) with untreated (as received) and H2SO4-treated coal bottom ash as catalyst were investigated in this study. Flynn-Wall-Ozawa (FWO) and distributed activation energy model (DAEM) isoconversional kinetic models were exploited to evaluate the kinetic parameters. The study was conducted using thermogravimetric analysis at 10, 20, 30, and 50 °C/min heating rates. The activation energy (Ea) and pre-exponential factor (A) for non-catalytic PKS decomposition for DAEM ranged from 74.39 to 217.05 kJ/mol and 4.77E+01 to 1.99E+14 s−1 at different conversions while for the untreated ash, the ranges were 103.84–402.53 kJ/mol and 7.35E+03–1.04E+29 s−1. In the decomposition with treated ash, Ea and A were 81.79–191.07 kJ/mol and 1.61E+02–1.20E+12 s−1 for 7 wt% ash and 74.41–137.35 kJ/mol and 4.91E+03–4.53E+08 s−1. Values of Ea and A obtained for FWO followed the same pattern and are in close agreement with that obtained using DAEM. The use of 10 wt% acid-treated ash reduced the activation energy compared with the non-catalytic process by about 33.05% while the untreated ash increased the activation energy. The kinetic parameters were determined satisfactorily using the first-order reaction mechanism.

Investigation of activation energy and antibacterial activity of CuO nano-rods prepared by Tilia Tomentosa (Ihlamur) leaves

In recent years, fabrication of metal oxide nanoparticles is intensively gained interest of various chemists as well as biochemist due to their wide range of applications in different fields. Therefore, we reported an easy and eco-friendly synthesis of CuO nano-rods by using Tilia Tomentosa (Ihlamur) leaves extract. Producing CuO nanoparticles exhibiting rod like shape is rare and difficult using plant leaves; but it is possible using tilia leaves. The green synthesised CuO nano-rods were calcined at 400˚C for 15 minutes and were characterized by UV-Visible spectroscopy, XRD, SEM and particle size analyser to study their bandgap, phases, shape and sizes respectively. SEM studies reveal the formation of rod shaped CuO nanoparticles with average length of 95nm and that of breadth is 32nm. Further the thermal properties of CuO nano-rods were studied by using TG and DTA analysis. Thermal studies were carried out at 6, 8 and 10˚/min heating rates to study the enthalpy and activation energy in detail. The activation energy of CuO nano-rods were calculated by Kissinger method and was found to be 12.23 kJ/mol. Antibacterial activity of CuO nano-rods are carried out using S. aureus, P. flourescens, E. faecalis, B. subtilis, S. enteridis and E. coli.

Influence of Purge Gas Flow and Heating Rates on Volatile Organic Compound Decomposition during Regeneration of an Activated Carbon Fiber Cloth

Five-cycle adsorption/regeneration experiments using 1,2,4-trimethylbenzene (TMB) were completed at different purge gas flow and heating rates to identify their impact on heel buildup. Regeneration of a saturated activated carbon fiber cloth was completed at 400 °C using resistive heating at different heating rates and purge gas flow. At 1 standard liter per minute (SLPM) desorption purge gas, increasing the regeneration heating rate from 5 to 100 °C/min increased heel buildup from 4.6 to 10.4 wt % and adsorption capacity loss from 7.8 to 52.0%. On the other hand, at 70 °C/min heating rate, increasing the purge gas flow rate from 0.1 to 5 SLPM decreased heel buildup from 14.6 to 1.4% and capacity loss from 82.3 to 2.1%. Increasing the heating rate or decreasing the purge gas flow results in higher TMB concentrations being exposed to the high desorption temperature and higher residence time of TMB in the adsorbent pores. This increases adsorbate decomposition, causing deposition of pore-blocking, high carbon content residue (coke) onto the adsorbent surface. These results show the importance of optimizing desorption conditions to minimize heel buildup during cyclic use, contrary to conventional wisdom, suggesting that higher heating rates are consistently preferred, and provide improvements in energy use.

Mineralogical Analysis of Portland Cement Pastes Rehydrated

Hydrated products, such as (hydrated) cement pastes, decomposition through physical-chemical alterations when submitted to high temperatures. One of the main factors that lead to microstructural changes during calcination up to 800ºC, is the dehydration phases of hydrated Portland cement. The present study sought to characterize crystalline phases occurring before and after calcination to the produced pastes using X-ray diffraction (XRD) analysis. Cement pastes were produced using Portland cement CP V-ARI RS, similar to type II (ASTM C150-07), with water/cement ratio 0.5. After a 28-day curing period, the pastes were calcinated at 800°C for 60 minutes with a 10°C/min heating rate. Afterwards, the newly produced hydraulic binder was cooled abruptly and reactivated through a rehydration process, and underwent analyses on the 7 and 28 day. During this study it was observed that the originally hydrated products can be rehydrated.

Characteristics of Low-Temperature Polyvinyl Chloride Carbonization by Catalytic CuAl Layered Double Hydroxide

A good way to make carbon materials was presented in low-temperature polyvinyl chloride (PVC) carbonization by catalysis. The process of low-temperature PVC carbonization by CuAl-layered double hydroxide (CuAl-LDH) was investigated by thermogravimetric analysis (TGA) and tubular furnace. The results show that CuAl-LDH accounting for 5% of PVC mass enabled acceleration of the dehydrochlorination in PVC as soon as possible and maximized the yield of the PVC carbonized product. The vacuum with 0.08 MPa, 20 °C/min heating rate and 90 min carbonized maintenance time were optimal for PVC carbonization. Moreover, the best morphology and yield of the carbonized product was provided at a carbonization temperature of 300 °C.

Alternative approach for safe disposal of dry olive pomace: pyrolysis with/without physical preprocessing

The aim of this study is to present an alternative approach for disposal by using pyrolysis for dry olive pomace (which is the leftover portion of raw olive pomace), which constitutes a problem in olive oil production facilities. In this context, dry olive pomace was pyrolyzed at 600 °C and two different pyrolysis durations: 5 °C/min heating rate without retention (total pyrolysis duration is 80 min) and 1 °C/min heating rate with 30-min retention after reaching target pyrolysis temperature (total pyrolysis duration is 550 min). Afterward, the effects of the dry olive pomace mixed with the olive mill wastewater and the pomace particle size during the pyrolysis process were evaluated in terms of pyrolysis product yields, inorganic contents of chars and organic fractions of bio-oil. While mixing of pomace within the wastewater resulted in an increase in the pyrolysis liquid, the effects of pomace particle size on pyrolysis product yields changed based on the pyrolysis conditions. A decrease in the particle size from 2 to 0.85 mm resulted in an increase in gas by 37.3% and a decrease in liquid by 37% at the pyrolysis process of 80 min. Furthermore, the decrease in the pomace size in grinding preprocess enhanced pyrolysis liquid quality in terms of a decrease in oxygenated compounds by 5–13% and an increase in aliphatic compounds by 7–20% at both pyrolysis durations. Consequently, dry olive pomace pyrolysis can be stated as one of the effective alternatives for safe disposal by converting waste into useful end products.

Thermogravimetric kinetics of catalytic and non-catalytic pyrolytic conversion of palm kernel shell with acid treated coal bottom ash

The catalytic and non-catalytic pyrolytic conversion kinetics of palm kernel shell with untreated (as received) and H2SO4 treated coal bottom ash as catalyst were investigated in this study. The activation energy was determined using Flynn-Wall-Ozawa (FWO) kinetic model and distributed activation energy model (DEAM) isoconversional kinetic models. The study was conducted using thermogravimetric analysis at 10, 20, 30 and 50 °C/min heating rates. The activation energy (Ea) ranged from 145.7-228.3 kJ/mol and 142.1-274.2 kJ/mol for FWO and DEAM, respectively. The use of acid treated ash reduced the activation energy compared to the non-catalytic process while the untreated ash increased the activation energy.

Gasification of Eucalyptus Wood Chips in a Downdraft Gasifier for Syngas Production in South Africa

ABSTRACT The present research article aims to study the gasification of eucalyptus as wood chips for syngas production and its thermogravimetric analysis (TGA) in a nitrogen atmosphere. The eucalyptus wood chips were sourced from a sawmill industry, cut into desired sizes and subjected to gasification in a downdraft gasifier using air as the oxidizing agent. The compositions of the syngas were measured using non-dispersive infrared gas sensors and a palladium/nickel (Pd/Ni) gas sensor. Thermogravimetric analysis was carried out under 20°C/min heating rate using a Perkin-Elmer thermogravimetric analyzer TGA 7 and the gasification zones temperatures were monitored using thermocouples. An average higher heating value (HHV) of 6.08 MJ/Nm 3 containing predominantly of hydrogen, carbon monoxide and methane was obtained from the eucalyptus syngas. The volumetric compositions of the syngas produced varied from 22.3% - 22.5% for hydrogen, 22.3% – 24.3% for carbon monoxide, 1.9% - 2.1% for methane, 9.8% - 10.7% for carbon dioxide and 41.5% – 42.9% for nitrogen. Nitrogen composition was highest due to the use of air as the oxidizing agent. The study have successfully demonstrated gasification as an alternative technology for conversion of waste to energy.

Synthesis and heating rate effect on the mechanical properties of NiAl intermetallic compound

This present study revealed the synthesis and heating rate effect on the mechanical attributes of spark plasma sintered NiAl intermetallic compound. The milled specimen was consolidated by field assisted sintering technique (SPS), morphology of the specimens was determined using the scanning electron microscope. The microstructures of the sintered NiAl that was carried out between the heating rates of 50 to 150 °C/min showed the presence of micro pores. The hardness value (Vickers microhardness) of the specimens was found to increase while the heating rate increases. Furthermore, highest hardness value of 555.4 HV0.1 was recorded for the sintered pellet possessing the heating and cooling rate of 150 °C/min. In addition, the densification of the sintered specimen (150 °C/min heating rate) was measured as 96.2%.

Investigation of phase transformation in Fe microalloyed Ti6Al4V alloy during continuous heating process

The phase transformation and dilatometric curves in Fe microalloyed Ti6Al4V alloy (Ti6Al4V-Fe) during continuous heating at 1 ℃ /min heating rate had been studied by dilatometer and metallographic methods, and β phase transition temperatures of alloy were obtained. In order to validate the accuracy of these β phase transition temperature and microstructure evolution, the relative phase concentration and the evolution of microstructure which were acquired by cooling after tempering were analyzed by metallographic microscope. The results illuminated that the expansion method was able to accurately measure the β transformation temperature of Ti6Al4V-Fe alloy. The lathy-shaped α phase decreased significantly disappeared in the range of 838℃ to 988℃, and the α→β phase transformation occurred.

Comparison of single- and multi-ramp bulk kinetics for a natural maturity series of Westphalian coals: Implications for modelling petroleum generation

We present a comprehensive new pyrolysis data set for a maturity series (0.55–2.86% vitrinite reflectance) of Pennsylvanian coals (Westphalian, Ruhr Basin). The broad similarity of the organofacies was established by elemental and petrographic data. Comparison of maximum temperatures reached by the coals was based on commonly applied algorithms (Easy%Ro, Easy%RoDL, Basin%Ro). These temperatures were finally compared to predicted temperatures of petroleum generation from the same coals in order to test the reliability of kinetic data for numerical petroleum generation reconstruction from coal. Kinetic parameters were determined based on data from open-system pyrolysis performed on two instruments (Rock-Eval™ and Source Rock Analyzer™) and basin modelling was performed using PetroMod™ software and a simple, rapid burial and heating history (about 20 °C/million years), which is similar to the rapid heating which caused natural maturation of these coals.With increasing maturity, pyrolysis curves shift towards higher temperatures, no matter which heating rate is used. However, pyrolysis curves of higher maturity samples are not embedded within the more extended and larger pyrolysis curves of low maturity coals. HI values and H/C ratios do not significantly decrease over the maturity range from 0.55 to 0.8–0.9% vitrinite reflectance. These observations indicate significant restructuring of organic matter in coals and only limited petroleum generation and expulsion within this maturity range.The kinetic parameters were derived from single (5 °C/min) and multiple (0.7, 2, 5, 15 °C/min) heating rate pyrolysis tests. After temperature correction, kinetic parameters obtained by the two instruments differ only slightly.Kinetics based on multiple heating rates using a variable frequency factor and variable activation energies provide the best mathematical fit to the laboratory data but geologically inconsistent predictions for natural petroleum generation, i.e. no increase in predicted generation temperatures with increasing sample maturity. In contrast, kinetics based on a constant, physically meaningful frequency factor and a calculated range of activation energies provide more consistent results for the maturity sequence. Interestingly, single-ramp kinetics (5 °C/min) show similar results, i.e. increasing calculated temperatures for petroleum generation with increasing maturity.For the lowest maturity sample, petroleum generation temperatures (10–75% conversion) are higher than calculated maximum rock temperatures, while this is not the case for all higher maturity samples, for which much of the predicted petroleum generation occurs at “too low” temperatures, i.e. temperatures clearly lower than calculated maximum rock temperatures. Maximum temperatures predicted by the Easy%RoDL approach are about 10 °C closer to the lower limit of petroleum generation than those calculated by Basin%Ro. Thus, kinetic data can act as a useful tool for calculating petroleum generation in petroleum system modelling providing clues towards the thermal stability of kerogen. However, such data are far from describing petroleum generation in nature exactly and quantitatively, especially for coals.

A Comparative Study On The Heat Release During The Combustion Of Coal And Oil Palm Biomass Charcoal Briquette Via Thermogravimetric Analysis (TGA)

The world is seriously searching for an alternative to fossil fuels due to their tremendous environmental effect. However, renewable energy sources such as solar, wind, hydropower, and biomass were anticipated to be alternative energies. In this study, the amount of heat generated from the combustion of coal and charcoal briquettes derived from oil palm biomass was investigated and compared. Charcoal briquettes were made from the biochar obtained after the pyrolysis of empty fruit bunches (EFB) and mesocarp fibre (MF). Coal and charcoal briquettes were subjected to combustion via thermogravimetric analysis (TGA) at a 10oC min-1 heating rate to a maximum temperature of 850oC. The ignition and burnout temperatures were 235oC and 675oC for EFB, 254oC and 788oC for MF, and 368oC and 770oC for coal. The maximum heat released 0.06 W was obtained from EFB charcoal briquette followed by 0.05 W and 0.04 W from coal and MF charcoal briquette, respectively. This finding indicated that charcoal briquettes derived from oil palm biomass (EFB) could be one of the potential solid fuels that can be used for coal replacement.
 Keywords: biomass, heat release, combustion, coal, charcoal briquette, TGA

Analysis on thermal behavior of fluorides and cyanides for heat-treating spent cathode carbon blocks from aluminum smelters by TG/DSC-MS & ECSA®

This paper adopts a novel data-processing method of ECSA® based on TG/DSC-MS system to basically study the characteristics of release and conversion of fluorides and cyanides during heat treatment of the spent cathode carbon block (SCCB). All the experiments were conducted at 10K⋅min-1 heating rate and under Ar or Ar-O2 atmospheres. The results indicate that the release of fluorides was just a steady but slow phase transition process under both Ar and Ar-O2 atmospheres, which can be comparatively accelerated when the carbon material was burnt. The cyanides were effectively decomposed at high temperature and at Ar-O2 atmosphere, with around three quarters of the cyanides being converted to the N2 and nearly a quarter being to the NO. Finally, analysis on the flue gas composition indicates that it had a more complicated composition of CO2, N2, NO, NO2, HCN under Ar-O2 atmosphere but only had a composition of CO2 and NO under Ar atmosphere.

Thermal decomposition of flexible polyurethane foams in air

The oxidative thermal decomposition of a non-fire retardant and a fire retardant polyurethane foam is investigated using thermogravimetric analysis and differential scanning calorimetry over 1–60 °C/min of heating rate, in both air and nitrogen environments. From the thermogravimetry results, the oxidative environment of air results in additional oxidative reactions which are heating rate dependent. These reactions compete with the pyrolysis reactions for the same reactants over similar temperature range. For both foams, increasing heating rate gradually reduces the influence from the oxidation of foam while favouring the pyrolysis of polyol. At low heating rate, in oxidative air environment, the fire retardant foam shows significant decomposition across low temperature range. This environment mimics the incipient phase of a fire, and ignition inhibition is possible when this low temperature decomposition is coupled with gas phase fire retardant mechanisms such as neutralisation of reactive radicals. Fire retardant additives also form char residue which notably lowers the decomposition rate while extending the decomposition temperature range, improving the overall thermal stability. Lastly, the kinetic properties governing the oxidative thermal decomposition of foams are estimated graphically using Inflection Point Methods, and the corresponding exothermic heat of reaction is determined from the heat flow results.

The investigation of production parameters of Ti-6Al-4V component by powder injection molding

Powder injection molding (PIM) is a production method that has advantages of casting and powder metallurgy in the production of parts from different materials, as well as being flexible in the production of complex shaped parts. In this article, experimental studies were carried out for injection and sintering of Ti-6Al-4V feedstock. The results were evaluated by Taguchi method and optimum parameters were determined. Sintering temperature has been determined as the most effective parameter on part quality. It was proven that the suitable set of injection and sintering parameters were as follows: feedstock flow rate of 30 cm3/s, injection pressure of 1100 bar, holding pressure of 70%, injection temperature of 150 °C, mold temperature of 40 °C, sintering temperature of 1250 °C, sintering dwell time of 120 min and sintering heating rate of 3 °C/min.

Influence of varied process parameters on the microstructure, densification and microhardness of spark plasma sintered Ti-6Al-4V/h-BN binary composite

The influence of varied process parameters involving three levels of temperature, pressure, heating rate and dwell time on the microstructure, densification and microhardness of spark plasma sintered Ti-6Al-4V/h-BN binary composite was studied. Taguchi design method was adopted to randomize the SPS process parameter levels. The microstructure was analyzed by optical microscopy, densification was determined based on the principle of Archimedes and Vickers microhardness tester was used to evaluate the microhardness of the sintered composite. The consolidation of Ti-6Al-4V powder and nanoparticles of 3 wt.% of h-BN via SPS produced nearly full theoretical densification of 99.77% and the sintered composite gave a microhardness value of 710.37 HV which is more than 200% that of the monolithic alloy. The best combination of relative densification and microhardness were obtained at the sintering parameters of 1000 °C of temperature, 40 MPa of pressure, 100 °C/min heating rate and 15 min of dwell time. Generally, it was found that improved microstructure, densification and microhardness were influenced by the high temperature of sintering and low rate of heating that gave room for adequate diffusional mass transport resulting in solid bonding between the particles of the matrix and the ceramic reinforcement.

Anhydrous weight loss kinetics model development for torrefied green waste

One of the compositions of municipal solid waste (MSW) is green waste (GW) that collected from landscaping, garden, yard and trimming waste. GW has potential in becoming a biomass feedstock, but poses some drawbacks such as high moisture content, low heating value, high O/C and H/C ratios. Implementation of torrefaction as pre-treatment will improve the GW properties. During torrefaction, biomass is decomposed and leads to anhydrous weight loss (AWL). The estimation model for AWL is significant to study thermal degradation of GW. The aim of this work is to study two steps reaction in series for AWL prediction. GW were torrefied under inert condition at 240-300°C, 10°C/min heating rate and 30 minutes holding time using thermogravimetric analysis (TGA). Two steps reaction series model named Di Blasi and Lanzetta with extended non-isothermal phase is used in developing the AWL model. From initial guess, the parameters of activation energy and kinetic constant are adjusted to fit the calculated AWL to experimental AWL data by applying nonlinear optimization ‘lsqcurvefit’ routine in Matlab. The estimated kinetic parameters been used for AWL model and later being compared to experimental data from TGA. Good agreement obtained between experimental and model data indicating good kinetic parameters estimation

Static and cyclic oxidation of Nb-Cr-V-W-Ta high entropy alloy in air from 600 to 1400 °C

An oxidation resistance study has been made on Nb-Cr-V-W-Ta high entropy alloy in a range of temperature from 600 to 1400 °C in air. Static oxidation study has been performed for either (a) 12 or 24 h of heating time or (b) 3 or 10 °C/min heating rates to the desired oxidation temperature. Cyclic oxidation study conducted for three and a half days has been conducted at 600, 700, and 800 °C using 12 h of heating cycles. The alloy can withstand the cyclic oxidation process with only a reasonable loss of alloy. The identification of oxides indicates crystals of W and Ta oxides in cylindrical form while Nb and Cr oxides show a nodular or granular morphology at both 1000 and 1200 °C while and additional of oxide of V in whisker forms at 1200 °C.

Biochar synthesis from sweet lime peel for hexavalent chromium remediation from aqueous solution

Sweet lime (Citrus limetta) peel biochar was obtained by slow pyrolysis of raw biomass at 450 °C with 5 °C/min heating rate. Proximate and ultimate analysis, physico-chemical characterization of the biochar was done. Batch adsorption experiments for Cr(VI) removal were performed with varying pH, biochar dose, contact time and initial Cr(VI) concentrations. It took 8–24 h to reach the equilibrium at 30 °C for varying Cr(VI) concentrations. The biochar was found to possess higher adsorption capacity (100 mg/g) than the adsorbents reported in several previous studies. Langmuir adsorption isotherm and pseudo second order model best explained the experimental data, suggesting monolayer adsorption as the dominant mechanism. Chemical interaction, ion exchange of solute and sorbate ions and physical adsorption also contributed into Cr(VI) adsorption process. Further, Cr(VI) adsorption was found to be a multistep process. The findings suggested that sweet lime peel biochar can be utilized as a low cost and efficient alternative for Cr(VI) removal, which could be useful for aqueous solutions, as well as to promote overall protection against soil and water degradation and pollution.

Comparative Analysis of Vaporization and Thermal Decomposition of Cyclotrimethylenetrinitramine (RDX)

Considering the need for accurate vaporization rates in the propellant combustion models, sublimation and vaporization rates of cyclotrimethylenetrinitramine (RDX) have been estimated over a wide range of temperatures. Simultaneous thermal analysis was carried at various slow heating rates, 5, 10, and 15°C/min, using a coupled TGA/DSC-FTIR system. In the solid phase, the mass loss occurs mainly due to the sublimation of RDX, whereas, in the liquid phase, both vaporization and thermal decomposition play a significant role. The extent of thermal decomposition was estimated using a computational model based on a recently developed detailed liquid-phase decomposition mechanism for RDX. For each of the heating rates, a suitable match between computational and experimental mass loss and species evolution profiles was achieved. As evident from the FTIR data, a major part of the mass loss occurs because of the evolution of decomposition products, such as , , , NO, HCN, , CO, and . Results show that vaporization accounts for 29.6, 34, and 35.9% of the total mass loss for the 5, 10, and 15°C/min heating rates, respectively. Relatively more RDX vaporizes at higher heating rates because of the initiation of the boiling phenomenon at higher sample temperatures.