• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.200.2-200.2
• /
• 2016

무전해 도금용 팔라듐 촉매액 중의 팔라듐 이온과 주석이온의 농도비($Sn^{2+}/Pd^{2+}$), 염산의 농도 및 첨가제의 농도 등은 촉매액의 안정성 및 흡착력에 영향을 미치는 것으로 알려져 있다. 무전해 도금용 콜로이드 타입 팔라듐 촉매액에 요구되어지는 특성으로는 1) 액 안정성이 양호하여 장시간 연속 사용에 있어서 나노입자의 응집 및 침전이 없을 것 2) 피도금체 표면에 흡착력이 양호할 것 3) 촉매활성이 충분하여 다음 공정인 무전해 도금피막의 초기석출성이 양호할 것 등이다. 본 연구에서는, 콜로이드 타입 팔라듐 촉매액 중의 염산 농도 및 금속이온의 농도비($Sn^{2+}/Pd^{2+}$), 첨가제를 변화시켜 촉매액의 안정성 및 촉매활성에 미치는 영향을 조사하였다. 그 결과를 시판의 팔라듐 촉매액과 비교하여 보고한다.

• Korean Chemical Engineering Research
• /
• v.61 no.4
• /
• pp.561-569
• /
• 2023

Furfural is a platform chemical that is produced from xylose, one of the hemicellulose components of lignocellulosic biomass. Furfural can be used as an important feedstock for phenolic compounds or biofuels. In this study, we compared and optimized the conditions for producing furfural from xylose in a batch system using two types of catalysts: sulfuric acid, which is commonly used in the furfural production process, and formic acid, which is an environmentally friendly catalyst. We investigated the effects of xylose initial concentration (10 g/L~100 g/L), reaction temperature (140~200 ℃), sulfuric acid catalyst (1~3 wt%), formic acid catalyst (5~10 wt%), and reaction time on the furfural yield. The optimal conditions according to the type of catalyst were as follows. For sulfuric acid catalyst, 3 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 10min of reaction time resulted in a maximum furfural yield of 59.0%. For formic acid catalyst, 5 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 150 min of reaction time resulted in a furfural yield of 65.3%.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.14 no.1
• /
• pp.169-177
• /
• 2006

In this study, it was studied that the removal rate of VOC by the catalytic combustion. The combustion temperature was changed by the contact type of VOC(space velocity and catalyst depth) and the space velocity(SV) was defined by the rate of gas volume flow rate(Q, $m^3/hr$) over volume(V, $m^3$) of catalyst (SV=Q/V). The space velocity of catalytic combustor is maintained $10,000{\sim}50,000hr^{-1}$. it was studied that the conversion rate of VOC by the catalytic combustion. The combustion temperature was changed by the contact type of VOC and catalyst and the space velocity was defined by the rate of gas volume flow rate over volume of catalyst. The VOC which pass thru the heat exchanger was measured by the hydro ionic detector and measured the VOC removal rate by the activated catalyst in the reaction temperature range of 373K-423K. The removal rate was measured over 100 times. In the automobile painting booth The VOC concentration was 63.37ppm and the removal rate was 70 % at 373K and 78.92% at 423K. The removal rate was increased as increased the temperature.

• Elastomers and Composites
• /
• v.49 no.2
• /
• pp.110-116
• /
• 2014

We investigated the effect of the concentration of stannous 2-ethylhexanoate catalyst on the esterification rate between adipic acid (AA) and each of two PEG oligomers, diethylene glycol (DEG) and polyethylene glycol (PEG600). The concentration of the catalyst was varied from 0.15 to 2.0 wt.%. To attach hydroxy group to each end of the poly(oxyethylene-co-adipate) synthesized from AA and the PEGs, the esterification was performed with excessive PEG oligomers ([PEG]/[AA]=2) at $170^{\circ}C$. The degree of polymerization of the poly(oxyethylene-co-adipate)diol products were three. The apparent rate constant ($k_{app}$) of the esterification between AA and DEG shows the first order dependency on the catalyst concentration ($k_{app}=0.88[C_{cat}]$), whereas the $k_{app}$ of the esterification between AA and PEG600 has a relation of $k_{app}=0.123[C_{cat}]^{0.55}$ with the catalyst concentration. It is expected that the rate of esterification between AA and DEG has a non-linear dependency on the catalyst concentration as the catalyst concentration approaches to 0.22M.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2006.11a
• /
• pp.323-327
• /
• 2006

전류밀도를 $1.0\;A/dm^2{\ell}$로 고정시키고, 촉매로 사용된 소금의 농도를 전체 폐수량의 약 15%로 조절하여 접촉시간을 $0\;{\sim}\;120$ 분으로 조절하여 각각의 시간에서 $COD_{Mn}$ 농도 약 70mg/L의 합성폐수를 전기분해 처리하여 접촉시간 약 30분에서 약 25 mg/L로 제거 되었으며, 60분이 지난 후부터 약 12 mg/L로 제거되는 것을 확인 할 수 있었다. 접촉시간을 1 시간으로 고정시키고, 촉매로 사용된 소금의 농도를 전체 폐수량의 약 15%로 조절하여 전류밀도를 $0\;{\sim}\;2.0\;A/dm^2{\ell}$로 조절하여 각각의 전류밀도에서 $COD_{Mn}$의 농도변화 실험결과 전류밀도 약 1.0 $A/dm^2{\ell}$에서 약 9 mg/L로 제거가 가능한 것으로 조사 되었다. 접촉시간을 1 시간, 전류밀도를 $1.0A/dm^2{\ell}$로 고정시키고 사용된 소금의 농도를 전체 폐수량의 $0\;{\sim}\;30\;%$로 조절하여 각각의 촉매 첨가율에서 $COD_{Mn}$의 농도변화를 조사결과 촉매 첨가율 30 %에서 가장 높은 처리효율을 나타내었으며, 촉매의 첨가에 의한 전기분해 효율뿐만이 아니라 직류전원공급기에 전기적 부하 또한 감소되는 것을 확인 할 수 있었다.

• Clean Technology
• /
• v.22 no.3
• /
• pp.161-167
• /
• 2016

Catalytic combustion of benzene over various metal cation-exchanged zeolites has been investigated. Y(4.8)-type zeolite showed the highest activity among the used zeolites and Cu/Y(4.8) catalyst also showed the highest activity among metal cation/ Y(4.8) zeolites. The catalytic activity increased according to the amount of adsorbed oxygen acquired from O₂ TPD results. The catalytic activity also increased with an increase of Cu cation concentration on Cu/Y(4.8) catalysts. The conversion of benzene on the combustion reaction depended on not benzene concentration but the oxygen concentration. In addition, the introduction of water into reactants decreased the catalytic activity.

• Clean Technology
• /
• v.22 no.4
• /
• pp.281-285
• /
• 2016

Cu wire catalyst was highly reactive toward catalytic wet peroxide oxidation of the highly refractory 1,4-dioxane. While complete removal of 1,4-dioxane could be achieved with the catalyst, the removed 1,4-dioxane could not totally mineralized into $CO_2$ and $H_2O$. In accordance with the disappearance of 1,4-dioxane, formaldehyde and oxalic acid were formed gradually with reaction time and they went through maxima. At around the time of maximum concentrations of these two intermediates acetaldehyde concentration was increased drastically and showed maximum value. With the disappearance of these three intermediates, formic acid together with ethylene glycol diformate began to increase gradually. The Cu wire catalyst was proved also to be highly stable against deactivation during the reaction.

• Korean Chemical Engineering Research
• /
• v.44 no.6
• /
• pp.650-658
• /
• 2006

The recycling of TDA from solid waste of TDI plant(TDI-R) by near-critical hydrolysis reaction had been studied by means of a statistical design of experiment. The main and interaction effects of process variables had been defined from the experiments in a batch reactor and the correlation equation with process variables for TDA yield had been obtained from the experiments in a continuous pilot plant. It was confirmed that the effects of reaction temperature, catalyst type and concentration, and the weight ratio of water to TDI-R(WR) on TDA yield were significant. TDA yield decreased with increases in reaction temperature and catalyst concentration, and increased with an increase in WR. As a catalyst, NaOH was more effective than $Na_2CO_3$ for TDA yield. The interaction effects between catalyst concentration and temperature, WR and temperature, catalyst type and reaction time on TDA yield had been defined as significant. Although the effect of catalyst concentration on TDA yield at $300^{\circ}C$ as subcritical water was insignificant, the TDA yield decreased with increasing catalyst concentration at $400^{\circ}C$ as supercritical water. On the other hand, the yield increased with an increase in WR at $300^{\circ}C$ but showed negligible effect with WR at $400^{\circ}C$. The optimization of process variables for TDA yield has been explored with a pilot plant for scale-up. The catalyst concentration and WR were selected as process variables with respect to economic feasibility and efficiency. The effects of process variables on TDA yield had been explored by means of central composite design. The TDA yield increased with an increase in catalyst concentration. It showed maximum value at below 2.5 of WR and then decreased with an increase in WR. However, the ratio at which the TDA yield showed a maximum value increased with increasing catalyst concentration. The correlation equation of a quadratic model with catalyst concentration and WR had been obtained by the regression analysis of experimental results in a pilot plant.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.11
• /
• pp.965-974
• /
• 2009

This study evaluated the degradation efficiency of malodorous sulfurized-organic compounds by utilizing N- and Sdoped titanium dioxide under visible-light irradiation, and examined the catalyst deactivation and regeneration. Catalyst surface was characterized by employing Fourier-Transform-Infrared-Red (FTIR) spectra. The visible-light-driven photocatalysis techniques were able to efficiently degrade low-level dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) with degradation efficiencies exceeding 97%, whereas they were not effective regarding the removal of high-level DMS and DMDS, with degradation efficiencies of 84 and 23% within 5 hrs of photocatalytic processes. As compared with DMS, DMDS which containes one more sulfur element revealed quick catalyst deactivation. Catalyst deactivation was confirmed by the equality between input and output concentrations of DMD or DMDS, the obsevation of no $CO_2$ generation during a photocatalytic process, and the FTIR spectrum peaks related with sulfur ion compounds, which are major byproducts formed on catalyst surfaces. The mineralization efficiency of DMS at 8 ppm, which was a peak value during a photocatalytic process, was calculated as 144%, exceeding 100%. The catalyst regenerated by high-temperature calcination exhibited higher catalyst recovery efficiency (53 and 58% for DMDS and DMS, respectively) as compared with dry-air and humid-air regeneration processes. However, even the calcined method was unable to totally regenerate deactivated catalysts.

• Korean Journal of Optics and Photonics
• /
• v.17 no.3
• /
• pp.296-302
• /
• 2006

ILow-temperature $TiO_2$ sol was synthesized with various catalyst contents by using a sol-gel method. $TiO_2$ thin films were produced by a dip-coating method and their optical, structural and photocatalytic properties were examined. Transmittance of $TiO_2$ thin films with 0.10 mol, 0.25 mol, 0.50 mol and 0.75 mol catalyst content showed high transmittance in the visible range. XRD results showed the anatase-to-rutile phase transition was accelerated with increasing catalyst content and the crystallinity size of the $TiO_2$ thin films increased with increasing catalyst content. SEM results indicated that the particle size of the $TiO_2$ thin films was the smallest with catalyst content of 0.25 mol. Photocatalytic results showed that methylene blue was completely decomposed in the presence of anatase film prepared with 0.10 mol, 0.25 mol and 0.50 mol catalyst content.