• Journal of the Korean Wood Science and Technology
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• v.25 no.1
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• pp.1-7
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• 1997

Kraft oak lignin and ricestraw lignin from acetosolve pulping were dissolved in 50/50 mixture of tetralin/m-cresol solvent. The dissolved lignin was reacted in the pressurized autoclave which was operating at $350{\sim}500^{\circ}C$ of reaction temperature and 10~20 atms of reaction pressure respectively_Hydrogen pressure of 60~80kg/$cm^2$ was exercising into the pressurized autoclave reactor to create thermochemical hydrogenolysis reaction. It was identified by GLC, GC-MS and HPLC that the alkyl-aryl-${\beta}$-O-4 ether bond of lignin was cleaved and degraded into various smaller molecules of aromatic compound such as phenols and cresols under the reaction conditions around $300^{\circ}C$ and 10 atms of reaction temoerature and pressure. Hydrogenolysis reaction of lignin compound which was done above $500^{\circ}C$ of reaction temperature and 20 atms of reaction pressure showed that the amount of aromatic compound such as phenols and cresols degraded from reactant lignin was decreasing with newly present and increasing water out of product mixtures. It was supposed that new aliphatic compound of high molecular weight hydrocarbon is composed due to higher reaction temperature and pressure of hydrogenolysis reaction such as $500^{\circ}C$ and 20 atms, even though it was almost impossible, to identify what kind of degraded products it was by HPLC.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.581-587
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• 2020

In this study, a new reaction system is proposed to solve the problems of the existing 2,3-Butanediol (2,3-BDO) dehydration reaction system. It was confirmed that the reaction system did not wok as it should operate properly when using a furnace, which is commonly used in commercial processes, to raise the reactant, 2,3-BDO, to the reaction temperature, 360 ℃, at near atmoshperic pressure. It is because of the substance considered to be oligomers of 2,3-BDO. It can lead to safety problems, such as blockages inside the furnace's tube and explosions, as well as tricky maintenance issues in the reaction system. To solve it, the temperature of reactant can be brought down by using a heat exchanger with High Pressure (HP) steam instead of the furnace, which has a hot spot problem through the vacuum operation and reduce the reaction temperature. It can be seen that the reactor performance is almost similar under the vacuum operation and the lower reaction temperature, 330 ℃, by using a reaction kinetics. This result explains why the new reaction system is proposed.

• Journal of the Korean Society of Safety
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• v.1 no.1
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• pp.27-32
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• 1986

To remove sulfur dioxide from flue gas by the method of metal oxide, copper powder of average diameter $2.4\mu\textrm{m}$and $51\mu\textrm{m}$ were used in a fixed bed reactor over a, temperature range of $300^{\circ}C-500^{\circ}C$. Copper oxide reacts with sulfur dioxide producing cupric sulfate and it can be regenerated from the latter by using hydrogen or methane. Experimental results showed that the reaction rate was increased by the increase of reaction temperature in the range of $300^{\circ}C-422^{\circ}C$ and the removal efficiency of sulfur dioxide was high in case of small size copper particle. However the removal efficiency was decreased at higher temperature due to decomposition of cupric sulfate. The rate controlling step of this reaction was chemical reaction and deactivating catalysts model can be applied to this reaction. The rate constants for this reaction and deactivation are as follows ： k＝8,367exp(-10,298/RT) Kd＝2.23exp(-8,485/RT)

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.44-49
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• 2000

Silicon nitride powders, were synthesized by the vapor phase reaction using SiH4-NH3 gaseous mixture. The reaction temperature, ratio of NH3 to SiH4 gas and the overall gas quantity were varied. The synthesized powders were characterized using X-ray, TEM, FT-IR and EA. The synthesized silicon nitride powders were in amorphous state, and the average particle size was about 100nm. TEM analysis revealed that the particle size decreased with increasing reaction temperature and gas flow quantity. As-received amorphous powders were annealed in nitrogen atmosphere at 140$0^{\circ}C$ for 2h, then the powders were completely crystallized at 0.2 ratio of NH3 to SiH4.

• Journal of the Korean Chemical Society
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• v.67 no.1
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• pp.28-32
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• 2023

The reaction conditions optimization, including the temperature of the reaction, amount of catalyst required, and reaction time for the linoleic acids (LAs) and conjugated linoleic acids (CLAs) production by catalytic dehydration of castor oil via saponification was investigated by response surface methodology (RSM). It was confirmed that all three parameters (temperature, time, and amount of catalyst) were influential factors in isolating LAs and CLAs. When the temperature was increased, the iodine value increased, and the reaction time and catalyst amount increased. The optimal reaction conditions were: 240 ℃, 2.2 h reaction time, and 7 wt% catalyst amount. The maximum iodine value reached 156.25 with 91.69% conversion to the essential fatty acids.

• Journal of Environmental Science International
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• v.13 no.7
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• pp.667-674
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• 2004

The objective of this study was to investigate the effects of pH and temperature on the formation of bromate, which is ozonation by-products, during ozonation. In this experiment, the operating parameters including pH 3 ～ 10 and temperature 15 ～ $30^{\circ}C$ were studied. Through the study for the bromate formation, reaction rate constant, and ozonation effect index on pH and temperature, the results obtained are as follows. At the same initial pH condition, the increase of pH shown similar trends even if the reaction variables such as temperature and reaction time of ozonation were exchanged. As pH and temperature were increasing, the bromate concentration was increased but bromine(HOBr+OBr) was decreased with increasing pH from 3 to 10. The activation energy(J/mol) for bromate formation decreased with increasing pH. The rate constants of bromate formation for the reaction of ozone and bromide, and ozone dosage coefficient$(K_{0})$ increased with temperature and pH. Ozonation effect index(OI) decreased with increasing temperature and pH.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.1-8
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• 2013

The aim of this study is to assess thermal hazards of polystyrene polymerization process by bulk polymerization with accelerating rate calorimeter(ARC) and Multimax reactor system(MM). From this study, we found out that the polymerization process should be operated at reaction temperature of $120^{\circ}C{\sim}130^{\circ}C$. At reaction temperature over $130^{\circ}C$, there was a runaway reaction hazard due to the temperature control failure following a viscosity increase of reaction products. With a cooling failure of a reactor in the early stage of process operation at the reaction temperature ($120^{\circ}C{\sim}130^{\circ}C$), there was a high thermal hazard of burst of a reactor's rupture disk or explosion of a reactor caused by the rapid rise of temperature and pressure to $340^{\circ}C$, 5.3 bar respectively within 30 - 50 minutes.

• Journal of Powder Materials
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• v.2 no.2
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• pp.149-157
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• 1995

In this study, an attempt was made to fabricate TiAl as well as its in situ composite via combustion synthesis. The processing variable of the combustion synthesis which include aluminum content and the heating rate were found to affect the combustion temperature. The combustion temperature measured, however, was lower than the melting temperature of TiAl and the reaction product were found to include incomplet reaction products. Carbon was added in order to increase the combustion temperature as well as to form in situ reinforcements. The reaction products showed homogeneous microstructures with carbide phases formed within indicating that the addition of carbon increased the combustion temperature above the melting temperature of TiAl.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.573-580
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• 1998

Self-propagating high temperature synthesis (SHS) technique was used to synthesize the spinel phase of $MgAl_2O_4$ from MgO and Al powder. Thermit reaction products of MgO and Al, The reaction products were heat treated at the temperature $800^{\circ}C$ preheating. Processing factors such as DTA/TG, combustium product and maxium temperature, synthesis of MgO and Al from "$MgO+2Al+3/2O_2$\rightarrow$MgAl_2O_4$". An activation energy (${\Delta}H^{\circ}$)-264.8 kcal/mol and reaction of maxium temperature 5634 K was calculated to form a $MgAl_2O_4$ spinel from unreacted materials. Pellet were increased volume 6% after thermit reaction. reaction.

• Journal of the Korean Society of Combustion
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• v.10 no.1
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• pp.20-26
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• 2005

In the present study, catalytic combustion of hydrogen-air premixture in a millimeter scale monolith coated with Pt catalyst was investigated. As the combustor size decreases, the heat loss increases in proportion with the inverse of the scale of combustion chamber and combustion efficiency decreases in a conventional type of combustor. Combustion reaction assisted by catalyst can reduce the heat loss by decreasing the reaction temperature at which catalytic conversion takes place. Another advantage of catalytic combustion is that ignition is not required. Platinum was coated by incipient wetness method on a millimeter scale monolith with cell size of $1{\times}1mm$. Using this monolith as the core of the reaction chamber, temperatures were recorded at various locations along the flow direction. Burnt gas was passed to a gas chromatography system to measure the hydrogen content after the reaction. The measurements were made at various volume flow rate of the fuel-air premixture. The gas chromatography results showed the reaction was complete at all the test conditions and the reacting species penetrated the laminar boundary layer at the honeycomb and made contact with the catalyst coated surface. At all the measuring locations, the record showed monotonous increase of temperature during the measurement duration. And the temperature profile showed that the peak temperature is reached at the point nearest to the gas inlet and decreasing temperature along the flow direction.