Effect Of Thermal Pretreatment Research Articles

Effects of thermal pre-treatments on solid slaughterhouse waste methane potential

The effects of thermal pre-treatments on the biogas production potential of two solid slaughterhouse waste types (poultry and piggery slaughterhouse by-products) were assessed by means of batch experiments. Both animal by-products were characterized in terms of fat, protein and carbohydrate concentrations. The selected thermal pre-treatments, pasteurization (70 °C for 60 min) and sterilization (133 °C and 3 bars for 20 min), are included in the current European regulations for the disposal or use of animal by-products. The pre-treatments produced notable improvements in organic matter solubilization, but had different effects on the anaerobic bioavailability of the treated substrates. The methane yield of the initial volatile solids did not increase significantly after pre-treatment when carbohydrate concentration was high, reaching a maximum of 0.48 m CH 4 3 kg VS - 1 for the pasteurized poultry waste. However, this yield increased by up to 52.7% after pasteurization and 66.1% after sterilization for the lower carbohydrate concentration sample (piggery waste), reaching maxima of 0.88 and 0.96 m CH 4 3 kg VS - 1 , respectively. The maximum methane production rates, measured as the maximum slope of the accumulated methane production curve, per unit of initial biomass content, were also different. While this rate increased by 52.6% and 211.6% for piggery waste after pasteurization and sterilization, respectively, it decreased by 43.8% for poultry waste after pasteurization with respect to untreated waste. Compounds with low biodegradability that are produced by Maillard reactions during thermal pre-treatment could explain the low bioavailability observed for waste with a high carbohydrate concentration.

Repair of plasma-damaged p-SiOCH dielectric films in supercritical CO 2

The silylation of plasma-damaged p-SiOCH low- k dielectric films was investigated with trimethychlorosilane (TMCS), hexamethyldisilazane (HMDS) and dimethyldichlorosilane (DMDCS) dissolved in supercritical CO 2 (scCO 2) and the effect of thermal pre-treatment on the repair performance was also studied. The surface hydrophobicity was rapidly recovered by silylation and the order of recovery efficiency was HMDS (85.4°) > DMDCS (83.4°) > TMCS (75.0°). The FTIR analyses revealed that the restoration to the original state was not achieved over various reaction conditions (up to 31 MPa, 85 °C, and 3 h reaction time). After pre-treatment in a vacuum cell at 250 °C, the Si–O–Si peak intensity increased slightly, and the surface hydrophobicity was partially recovered to 54.4° due to the removal of physically adsorbed H 2O molecules as well as some extent of dehydration of neighboring surface silanol groups. The hydrophobicity increased to 84.4° after subsequent treatment with HMDS in scCO 2. From DSIMS, the carbon concentration did not increase in bulk region after silylation of thermally pre-treated low- k films.

Effect of thermal pretreatment on recovery of nickel and cobalt from Sukinda lateritic nickel ore using microorganisms

Experimental investigation made previously on microbiological leaching of nickel and cobalt from the laterite nickel ore of Sukinda Valley reveals that the recovery was not very much promising under any favorable conditions. Therefore, in order to improve the efficiency for bioleaching, the homogenized lateritic ore in palletized form is thermally pretreated by roasting at different temperatures. The parameters studied for the bioleaching experiments were the four types of pretreated ore which were roasted at different temperatures, i.e., 300 °C, 400 °C, 600 °C and 800 °C, in shake flask by using a mixed mesophilic acidophilic bacterial consortium consisting predominantly of the Acidithiobacillus ferrooxidans strain. It was observed that the pretreated ore at 600 °C with 10% (w/v) pulp density showed maximum recovery of nickel and cobalt, i.e., 59.18% (4.556 ppm) and 65.09% (0.546 ppm), using 10% (v/v) (2.5 × 108 cells/ml) consortium concentration at 1.5 pH, 30 °C, and 150 rpm after an incubation period of 31 days.

Effect of High Temperatures on the Properties of Alkali Activated Aluminosilicate with Electrical Porcelain Filler

The effect of thermal pre-treatment up to 1,200°C on the structure and properties of alkali-activated aluminosilicate material containing electrical porcelain filler is analyzed in this article. The material is found to have very good high-temperature resistance. The reasons for its positive response to high-temperature exposure are, on one hand, the formation and subsequent crystallization of akermanite, and on the another hand, melting of electrical porcelain filler in the alkali environment at about 1,150°C and its subsequent reaction with the porous matrix resulting in formation of ceramic bonds. The combination of these two positive effects complementing each other in the formation of a new structure is responsible for the structure compaction indicated by the sudden decrease in porosity and is manifested in quite remarkable improvement of mechanical properties.

Interfacial Impedance Study of Li-Ion Composite Cathodes during Aging at Elevated Temperatures

The interfacial impedance behavior of carbon black, , and composite electrodes during storage in , ethylene carbonate/ethyl methyl carbonate electrolyte at was investigated. The effect of thermal pretreatment ( under vacuum) prior to aging on the electrochemical properties of the electrodes was studied in detail. Electrochemical impedance measurements, which were carried out periodically during storage, showed that the electrodes’ interfacial impedance decreased substantially with the heat-treatment time, the rate of impedance increase upon storage in electrolyte at elevated temperatures was predetermined by the heat-treatment parameters, and physicochemical properties of carbon (carbon black) were primarily responsible for the observed interfacial impedance behavior of the electrodes during aging. Scanning electron microscopy, energy-dispersive X-ray, and Fourier transform infrared analysis of aged electrodes revealed a thin surface film of electrolyte decomposition products. Adsorbed water and oxygen containing surface groups on carbon reacted with the electrolyte to produce inorganic and organic surface deposits. The thin-film formation on carbon black particles during aging, and consequently, a gradual loss of electronic conductivity within the electrode is most likely responsible for degradation of electrochemical performance.

Propane Conversion to Aromatics on Highly Active H-GaAlMFI: Effect of Thermal Pretreatment

The propane aromatization activity over H-GaAlMFI has been investigated after different thermal pretreatments (calcination temperature range: 500−800 °C) at a reaction temperature of 500 °C and in the space velocity range of 1500−12000 cm3/g/h. The calcination temperature had a strong influence on the strong acidity of the zeolite, propane conversion, and aromatic distribution. The decrease in acidity with increased thermal treatment severity correlated well with the decrease in the framework Ga. There was a considerable decrease in propane aromatization activity at calcination temperatures above 600 °C. The effect of calcination temperature on the propane aromatization activity can be explained in terms of change in the strong acidity of the zeolite and the extraframework Ga content. The selectivity for aromatics was found to decrease with increasing thermal pretreatment severity, while that for methane, ethane, and propylene was found to increase. The aromatic distribution was also influenced by the th...

06/00802 Effects of thermal pretreatment in helium on the pyrolysis behaviour of Loy Yang brown coal: Zeng, C. et al. Fuel, 2005, 84, (12–13), 1586–1592.

The purpose of this study is to investigate the structural changes in nascent chars during the gasification of two low-rank coals in CO2 at 1000 °C and 1200 °C. Western Australian Collie sub-bituminous coal and Victorian Loy Yang brown coal were heated up at 1000 K s−1 in He/CO2 in a wire-mesh reactor. FT-Raman spectroscopy was applied to understand the key structural features of nascent chars. For comparison, the Raman data of the chars produced in a drop tube furnace in N2/CO2 at 1200 °C for Loy Yang coal were also included in this study. The results showed that the evolution of char structure was determined by the counteracting effects of thermal annealing and oxygenation during the initial holding at 1000 °C (<1 s). With further holding at 1000 °C or holding at 1200 °C, the rapid formation of O-containing functional groups and the selective consumption of small aromatic rings took place. For each coal, there was no significant change in reaction pathway between gasification at 1000 and 1200 °C. Combining the data from FT-Raman and FT-IR spectroscopy, there appears to be more than one type of O-containing functional groups formed during the gasification in CO2. Some are more sensitive to Raman scattering but some are more sensitive to FTIR absorption.

Influence of Degassing Temperature on the Performance of Carbon Molecular Sieves for Separations Involving O2, N2, CO2, and CH4

The effect of thermal pretreatment on the diffusion of O2, N2, CO2, and CH4 at 298 K in the commercial carbon molecular sieve Takeda 3A was studied. The results indicate that pore mouth barrier controls nitrogen transport. For oxygen and carbon dioxide, however, two mechanisms are present. Pore mouth barrier control determines the transport at lower temperature degassing, and micropore diffusion is present with a high temperature degassing. When the degassing temperature is increased, the adsorption as a function of contact time is almost constant for O2 and CO2, is almost null for CH4, and increases significantly for N2 between 373 and 653 K. The rates of diffusion also increase with increasing degassing temperature, but more appreciably for N2, which results in a significant decrease in selectivity for O2/N2 and CO2/N2 separations. These separations are therefore more efficient for Takeda 3A if it is only subjected to temperatures lower than 373 K. On the other hand, for CO2/CH4, the separation is more efficient if the Takeda 3A sample is first submitted to a degassing temperature around 673 K.

Catalytic Dehydration of Alcohols Using Thermally Pretreated Manganese Material

The effect of thermal pretreatment on manganese material properties was investigated via XRF, DSC, XRD, MIP, and surface acidity measurements. The catalytic activity toward dehydration of different alcohols ethanol (in comparison with synthetic manganese catalyst), 1-propanol and 1-butanol was also carried out in a catalytic flow type system in the presence of hydrogen stream under atmospheric pressure with reaction temperatures ranging from 200–550°C and at different space velocities between 0.46–15.40 h−1. The results showed an agreement between manganese calcined material and the prepared catalyst in the optimum reaction temperature required for the dehydration of ethanol to ethylene, as well as the selectivity values. Data showed decrease in total dehydration conversion percentage in the order ethanol > 1-propanol > 1-butanol.

The effect of thermal pretreatment on the electrochemical response for palladium in aqueous media

Previous work on the electrochemistry of palladium in aqueous acid solution demonstrated the existence of two multilayer hydrous oxide reduction peaks, one at ca. 0.24 V and another at ca. 0.55 V vs. RHE, plus the presence of a reversible active surface state transition at ca. 0.24 V. In the present work with thermally activated palladium it was observed that, in agreement with the hydrous oxide reduction behaviour of the system, there is a second active state transition at E≥ca. 0.45 V. In most of its reactions in aqueous acid solution, apart from its unusual capacity to absorb hydrogen, palladium exhibits properties very similar to those of platinum; however, palladium seems to be more prone to dissolution and subsurface oxygen formation. Also the premonolayer oxidation responses of these two metals are often different as the more active state of the palladium surface is not as readily generated as that of platinum. The electrocatalytic properties of palladium, as reported earlier, correlate quite well with the hydrous oxide and premonolayer oxidation behaviour of this electrode system.

Effects of thermal pretreatment on the redox behaviour of Ce0.5Zr0.5O2: isotopic and spectroscopic studies

The temperature programmed reduction (TPR) of a single phase Ce0.5Zr0.5O2 solid solution is investigated by using 1H2/Ar and 2H2/Ar mixtures as reducing agents. The effects of mild (700 K) or severe (1273 K) pre-oxidation (MO, SO) on the TPR profile are analysed. It is observed that after SO pretreatment hydrogen activation/scrambling occurs at about 600 K and the reduction profile is characterised by a single reduction peak at 920 K. In contrast, a TPR/MO pretreatment of such SO sample leads to a facile hydrogen activation/scrambling and low temperature reduction profiles, the main reduction peak being observed at ca. 650 K. Using 1H2 and 2H2 as reducing agents, an isotopic effect is observed for the reduction processes with a peak occurring above 700 K, while equal activation energies are measured for those occurring below 700 K. This suggests that under the TPR conditions the surface reduction steps (activation of the reducing agent at the surface, surface reduction steps and water evolution) are not rate limiting for the low temperature reduction process, which is controlled by bulk diffusion, while some surface step (probably water formation) is limiting for the high temperature reduction. Studies by EPR on the nature of the oxygen species adsorbed on variously pretreated specimens and by FTIR of the methoxy species formed upon methanol adsorption on the same materials reveal that the main changes induced by high temperature calcination are related to segregation of ceria- and zirconia-type islands, with some surface enrichment in cerium probably occurring as well. Only subtle differences between SO and MO pretreated samples can be detected at either surface or bulk (XRD experiments) levels, in contrast with the significant modifications produced by the different pretreatments on the reduction characteristics of the sample.

Studies on Anaerobic Digestion Mechanism: Influence of Pretreatment Temperature on Biodegradation of Waste Activated Sludge

The effect of thermal pretreatment on hydrolysis, acidogenesis and methanogenesis during anaerobic digestion of waste activated sludge (WAS) was investigated. Pretreatment temperature of WAS ranged from 60°C to 120°C and the holding times were 5, 10, 20, 30 and 60 minutes. WAS was fed into the laboratory-scale anaerobic digesters, after thermal pretreatment. The preliminary conversion step (such as death/lysis of cell and hydrolysis of WAS) was promoted through thermal pretreatment, and consequently efficiencies of acidogenic and methanogenic steps were also markedly enhanced. Thermal pretreatment at lower temperature resulted in a significant increase in methane generation and destruction of organic matter. At 60°C, when hydraulic retention time (HRT) was 8 days, an increase in approximately 52.1 % in methane generation (ml. l−1. d−1) and 26.6% in organic matter destruction was achieved (Series-I). In addition, HRT necessary for anaerobic digestion could be reduced by thermal pretreatment.

Effects of Thermal Pretreatment (Removal of Steric Hindrance) on Subsequent Nuclear Hydrogenation of Heavy Alkylaromatics

The changes in structures by thermal pretreatment of heavy alkylaromatics, which are very difficult to nuclear hydrogenate, and the effects of the pretreatment on subsequent nuclear hydrogenation were investigated in comparison with catalytic pretreatment of the same feedstock. The following results were obtained: (1) the structures of the thermally pretreated products are quite different from those of the catalytically pretreated ones; (2) subsequent nuclear hydrogenation of the thermally pretreated products becomes much easier because the steric hindrance is removed; (3) in the case where the same feedstock was catalytically pretreated, the products were difficult to nuclear hydrogenate. These results suggest various applications, including heavy oil hydrotreating.

Effect of Thermal Treatments on the Properties of Nickel and Cobalt Activated-Charcoal-Supported Catalysts

The effect of thermal pretreatment in N 2 up to 723 K and the activation treatments in H 2 and an inert atmosphere on the properties of Ni and Co activated-charcoal-supported catalysts were studied. Catalysts were characterized by means of N 2 adsorption at 77 K, H 2 chemisorption at room temperature, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The catalysts′ activity and selectivity for acetone hydrogenation to 2-propanol under unusual and severe conditions (473 K and high overall acetone conversion) were also measured. TGA and XRD evidence was found for the charcoal-support-promoted NiO and CoO reduction to the metallic states when the catalysts were subjected to an inert atmosphere at 723 K. The thermal activation treatments under H 2 or inert atmosphere above 723 K caused a loss of acetone hydrogenation activity (calculated on a metal load basis) for both the Ni and Co activated-charcoal-supported catalysts, with respect to that of the low-temperature (573 K) activation treatments. In a series of activated-charcoal-supported Ni catalysts, a large decrease in the H 2 chemisorption uptake was also found for a sample pretreated in N 2 at 723 K prior to H 2 reduction. These results were not due to nickel or cobalt sintering, as shown by XRD line broadening measurements. The catalytic activity loss was accompanied by a decrease (in the case of Ni) and an increase (in the case of Co) in the 2-propanol selectivity.

細胞内デンプンの糊化に関する研究（第３報） 小豆子葉細胞内デンプンの糊化に及ぼす加熱前処理の影響

細胞内デンプンの糊化に関する研究（第３報） 小豆子葉細胞内デンプンの糊化に及ぼす加熱前処理の影響

Upgrading of Anaerobic Digestion of Waste Activated Sludge by Thermal Pretreatment

The effect of thermal pretreatment on the characteristics of degradation of waste activated slduge (WAS) in anaerobic digestion was investigated by laboratory-scale batch and continuous experiments at 35±1°C. The pretreatment temperatures of WAS ranged from 62 to 175°C and the pretreatment times were 15, 30, 60, 90 and 120 minutes. The organic particulates in WAS were solubilized to soluble carbohydrates, lipids and proteins or converted into the lower molecular weight compounds, such as volatile fatty acids, by the thermal pretreatment. Through the thermal pretreatment. the anaerobic degradability of WAS and the gas production from WAS were greatly increased, and the retention time necessary for anaerobic digestion was possible to be reduced by 5 days. The optimum pretreatment temperature and pretreatment time for the upgrading of anaerobic digestion of WAS were 170°C and 60 minutes, respectively. At this pretreatment condition, the COD removal and the gas production were markedly increased. At the digester with retention time from 5 to 10 days, the COD removal efficiency reached over 60% and gas production ranged from 223 to 235ml·gCOD−1 which were about 2 times those of the control. The numbers of methanogenic bacteria existing at retention times from 1.5 to 10.0 days ranged from 107 to 108 MPN·ml−1, and reached the maximum population level at the retention time of 5 days. The increase in solubilization and anaerobic degradation of major organic compounds in WAS by thermal pretreatment decreased in the following order: carbohydrates &amp;gt; proteins &amp;gt; lipids.

Processing and sintering of a 3 : 2 alumina silica gel

The aim of this work was to investigate the possibility of applying a conventional ceramic processing route to an amorphous mullite precursor. The main processing parameters necessary for high purity and dense mullite bodies were studied. The effect of thermal pretreatments on the sintering mechanism, density and microstructure of mullite compacts was established.

Effect of thermal pretreatment and reduction on acidity and metal state in doped NiH and CuH mordenites

AbstractThermal pretreatment such as calcination and steaming as well as the reduction of cations by hydrogen, affect the zeolitic acidity and activity of nickel‐ and copper‐doped mordenites in heterogeneously catalyzed reactions such as the conversion of n‐hexane. Data on acidity changes were obtained by IR spectroscopy, and information on ionic and metallic states by temperature‐programmed reduction, CO chemisorption and transmission electron microscopy (TEM). The findings were compared with reaction results from conversion of n‐hexane. Trimethylamine (TMA) was selected as a standardization molecule for semi‐quantitative determination of acidity. Correlation of relative acidity values with experimental results was possible only to a very limited extent. Results of CO chemisorption, TPR and TEM allow conclusions to be drawn on metallic crystallites, Ni+ and Cu+ ions and clusters, which appear to exert a stabilizing influence on zeolitic activity. Nickel crystallites with d &gt; 2 nm catalyze both hydrogenation and dehydrogenation of paraffins on the metal in bifunctional catalysis, as was also observed on platinum‐doped zeolites.

Catalytic behaviour of FeTi for CO methanation: Effect of Fe substitution with Mn and Ni

The catalytic behaviour of Fe 1− x M x Ti intermetallics with MMn or Ni (0.0⩽ x⩽0.5) has been investigated for CO methanation. For low values of x∼0.1, substitution by Mn is found to improve the catalytic activity of FeTi, whereas Ni substitution showed slight reduction in catalytic activity. The effect of thermal pretreatments in O 2 and H 2 on the catalytic properties of these materials has been studied. Conversion electron Mössbauer spectroscopic studies have revealed the generation of surface Fe clusters as a result of these pretreatments. The effect of substitution on catalytic activity is discussed in the light of oxidation characteristics of the constituent metals.

Effect of thermal pretreatment on the structural properties of [formula omitted] catalysts in hydrocarbon synthesis from CO and H 2

Two iron on MgO catalysts with the same iron content but subjected to different thermal pretreatments, prepared from magnesium hydroxycarbonate (MHC), have been studied. Chemisorption, Mössbauer spectroscopy and activity and selectivity measurements in a Fischer-Tropsch reaction have been combined to characterized them. The catalysts obtained show diverse structural properties and catalytic behaviour. When the supported crystallite size changed from 63 to 193 Å, the methane turnover frequency increased 3.5 times. For the reaction conditions used, 543 K, H( in2): CO = 3:1 and atmospheric pressure, the catalyst with larger iron particles produce a lower fraction of C 2+ in hydrocarbon products and showed a greater tendency to the deactivation and loss of C 2+ selectivity than the one with smaller particles. This behaviour is discussed in terms of the structural properties of Fe° microcrystals.