Effects of metal or metal oxide additives on oxidative coupling of methane using Na₂WO₄/SiO₂ catalysts: Reducibility of metal additives to manipulate the catalytic activity

Gu, Sangseo,Oh, Hyung-Suk,Choi, Jae-Wook,Suh, Dong Jin,Jae, Jungho,Choi, Jungkyu,Ha, Jeong-Myeong Elsevier 2018 Applied Catalysis A Vol.562 No.-

<P><B>Abstract</B></P> <P>The oxidative coupling of methane using silica-supported Na<SUB>2</SUB>WO<SUB>4</SUB> (Na<SUB>2</SUB>WO<SUB>4</SUB>/SiO<SUB>2</SUB>) catalysts is observed by adjusting additives in order to understand the roles of additives and to design more efficient catalysts. By observing the effects of additives on the catalytic OCM activity of Na<SUB>2</SUB>WO<SUB>4</SUB>/SiO<SUB>2</SUB> catalysts, the reducibility of metal additives, quantified by the standard reduction potentials, is observed to improve the methane conversion and olefin selectivity, indicating that the active sites of activating methane and dehydrogenating paraffin are identical. The supply of oxygen atoms from more easily reducible additives to tungsten oxide manipulate the OCM activity as described by the standard reduction potentials of the additives. The crystal and electronic structures of the catalysts depend on the additives, which can also be used to adjust the catalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Na<SUB>2</SUB>WO<SUB>4</SUB> catalyst was modified using metal or metal oxide additives for the oxidative coupling of methane. </LI> <LI> The additives with the higher standard reduction potentials improved the methane conversion and the dehydrogenation. </LI> <LI> Supply of oxygen atoms from addtives to tungsten oxide improved the OCM activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of additives on redox behavior of iron oxide for chemical hydrogen storage

Jae-Chun Ryu,Dong-Hee Lee,Kyoung-Soo Kang,박주식,Jong-Won Kim,김영호 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.2

The redox behaviors of iron oxides, which were modified with Pd, Pt, Rh, Ru, Al, Ce, Ti and Zr as additives, were investigated using temperature-programmed reaction (TPR) technique. The modified iron oxides were prepared by co-precipitation method using urea precipitant. The role of additives was also examined using XRD and SEM analysis in detail. As a result, Pd, Pt, Rh and Ru additives have an effect on promoting the reduction and lowering the re-oxidation temperature of iron oxide. Especially, it is revealed that the effect of Rh species on lowering the reduction temperature is attributed to decrease of activation energy for H₂ reduction according to Fe₂O₃→Fe₃O₄ course. Meanwhile, Al, Ce, Ti and Zr additives played an important role in prevention of deactivation of iron oxide by repeated redox cycles. Redox performances of iron oxides were also enhanced due to cooperative effects by co-addition of Rh and another species such as Al, Ce and Zr. Finally, Fe–O/(Rh, Ce, Zr) sample exhibited good performance for H2 evolution by water-splitting through synergistic effect of component additives

Effect of additives on redox behavior of iron oxide for chemical hydrogen storage

Ryu, J.C.,Lee, D.H.,Kang, K.S.,Park, C.S.,Kim, J.W.,Kim, Y.H. Korean Society of Industrial and Engineering Chemi 2008 Journal of industrial and engineering chemistry Vol.14 No.2

The redox behaviors of iron oxides, which were modified with Pd, Pt, Rh, Ru, Al, Ce, Ti and Zr as additives, were investigated using temperature-programmed reaction (TPR) technique. The modified iron oxides were prepared by co-precipitation method using urea precipitant. The role of additives was also examined using XRD and SEM analysis in detail. As a result, Pd, Pt, Rh and Ru additives have an effect on promoting the reduction and lowering the re-oxidation temperature of iron oxide. Especially, it is revealed that the effect of Rh species on lowering the reduction temperature is attributed to decrease of activation energy for H<SUB>2</SUB> reduction according to Fe<SUB>2</SUB>O<SUB>3</SUB>->Fe<SUB>3</SUB>O<SUB>4</SUB> course. Meanwhile, Al, Ce, Ti and Zr additives played an important role in prevention of deactivation of iron oxide by repeated redox cycles. Redox performances of iron oxides were also enhanced due to cooperative effects by co-addition of Rh and another species such as Al, Ce and Zr. Finally, Fe-O/(Rh, Ce, Zr) sample exhibited good performance for H<SUB>2</SUB> evolution by water-splitting through synergistic effect of component additives.

삼나물-페퍼민트 혼합물의 첨가 농도가 물속 콩기름 에멀션의 소비자 기호도와 지방질 산화안정성에 미치는 영향

이경애(Kyong-Ae Lee),최은옥(Eunok Choe) 한국식품조리과학회 2018 한국식품조리과학회지 Vol.34 No.5

Purpose: Consumer acceptance and lipid oxidative stability of soybean oil-in-water emulsions with added samnamul (Aruncus dioicus)-peppermint (Mentha × piperita) mixture were investigated. Methods: The emulsions basically consisted of refined, bleached, and deodorized soybean oil (40 g) and citrate buffer (60 g, pH 4.0) with samnamul-peppermint extract mixture (1:1, w/w) added at 0, 400, 800, or 1,200 ㎎/㎏ that were stored at 25℃ under light (2,600 lux) for 4 days. Consumer acceptance of color, taste, smell, mouthfeel, and overall liking of emulsions was evaluated with 100 panels, and lipid oxidation was evaluated based on the peroxide and p-anisidine values. Results: Consumer acceptance of the color, taste, mouthfeel, and overall liking of the emulsion improved in response to addition of the samnamul-peppermint extract mixture; however, there was no significant difference in acceptance among emulsions amended with 400, 800, and 1,200 ㎎/㎏ (p>0.05). The degree of lipid oxidation was higher in emulsions containing the added samnamul-peppermint extract mixture, and there was an increasing tendency as the amount added increased. However, there was no significant effect (p>0.05) on the rates of lipid oxidation. Conclusion: The optimum level of samnamul-peppermint extract mixture for an oxidation-stable and consumer acceptable soybean oil-in-water emulsion was 400 to 800 ㎎/㎏ based on consumer acceptance and lipid oxidative stability.

STS 316L 소결체의 부식 저항 특성에 미치는 금속산화물 첨가의 영향

이종필,홍지현,박동규,안인섭,Lee, Jong-Pil,Hong, Ji-Hyun,Park, Dong-Kyu,Ahn, In-Shup 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.4

As wrought stainless steel, sintered stainless steel (STS) has excellent high-temperature anti-corrosion even at high temperature of $800^{\circ}C$ and exhibit corrosion resistance in air. The oxidation behavior and oxidation mechanism of the sintered 316L stainless was reported at the high temperature in our previous study. In this study, the effects of additives on high-temperature corrosion resistances were investigated above $800^{\circ}C$ at the various oxides ($SiO_2$, $Al_2O_3$, MgO and $Y_2O_3$) added STS respectively as an oxidation inhibitor. The morphology of the oxide layers were observed by SEM and the oxides phase and composition were confirmed by XRD and EDX. As a result, the weight of STS 316L sintered body increased sharply at $1000^{\circ}C$ and the relative density of specimen decreased as metallic oxide addition increased. Compared with STS 316L sintered parts, weight change ratio corresponding to different oxidation time at $900^{\circ}C$ and $1000^{\circ}C$, decreased gradually with the addition of metallic oxide. The best corrosion resistance properties of STS could be improved in case of using $Y_2O_3$. The oxidation rate was diminished dramatically by suppression the peeling on oxide layers at $Y_2O_3$ added sintered stainless steel.

식품첨가제를 첨가한 전해산화수의 세정효과

정승원,정진웅 한국식품저장유통학회(구 한국농산물저장유통학회) 2002 한국식품저장유통학회지 Vol.9 No.2

세정수로서의 전해산화수 효능을 증대시키기 위하여 다양한 식품첨가제를 첨가하여 제조한 0℃ 이하의 세정수에 대한 냉각특성, 살균 및 갈변억제 효과를 조사하였다. 식품첨가제의 첨가비율은 NaCl 0.85%(w/v), ethanol 0.5%(v/v), 레몬과즙 0.5%(v/v), 유자과즙 0.5%(v/v), polysorbate 80은 1 ppm으로 결정하였다. 미생물 사멸효과는 초기 5.63×10exp(8) CFU/mL인 Escherichia coli KCTC 1039가 모든 첨가구에서 15∼30초 이내에 전부 사멸하였으며, Bacillus cereus KCTC 1012는 polysorbate 80 및 ethanol 첨가구에서 2분 후, Lactobacillus plantarum KCTC 3108은 polysorbate 80, 유자 및 레몬과즙 첨가구에서 30초만에, 그리고 Erwinia carotovora subsp. carotovora KCTC 2776은 polysorbate 80 및 레몬과즙 첨가구에서 30초만에 사멸하는 효과를 나타내었다. 갈변억제효과는 polyphenol oxidase의 활성을 측정하여 비교한 결과, ascorbic acid 0.5% 첨가구에 5분간 침지하였을 때 57%의 활성저해를 제외한 모든 처리구에서 62∼84%의 높은 활성저해 효과를 보였으며, 그 중에서도 NaCl 및 유자과즙 첨가구에서 30분 침지시에 각각 64, 91 units로 가장 낮은 활성을 보여주었다. 절단 감자를 30분간 침지처리한 후의 색도에서도 대부분의 처리구에서 색차(ΔE)가 3 이하를 나타내었다. This study, to enhance the sterilization, browning inhibition and precooling effect of electrolyzed oxidizing water(EOW) as cleaning water on food industry, was carried out to investigate the efficacy of electrolyzed oxidizing water(EOW) with 0.85% NaCl, 0.5% ethanol, polysorbate 80 of 1 ppm, 0.5% lemon juice and 0.5% citron juice. Escherichia coli KCTC 1039 with initial count of 5.63×10exp(8) CFU/mL were reduced to <10^1 CFU/mL after 15∼30 sec when it was treated by electrolyzed oxidizing water added with various food additives. Bacillus cereus KCTC 1012 were reduced to <10^1 CFU/mL after 2 minutes treatment with electrolyzed oxidizing water containing polysorbate 80 and ethanol. Lactobacillus plantarum KCTC 3108 were reduced to <10^1 CFU/mL after 30 sec treatment with electrolyzed oxidizing water containing polysorbate 80, citron juice and lemon juice, respectively. Erwinia carotovora subsp. carotovora KCTC 2776 were reduced to <10^1 CFU/mL after 30 sec treatment with electrolyzed oxidizing water containing polysorbate 80 and lemon juice. Browning inhibition effect was determined by comparison of polyphenol oxidase activity. Inhibition ratio of polyphenol oxidase was approximately 62∼84% in most treatments with the exception of 57% and 25% inhibition by 0.5% ascorbic acid and polysorbate 80, respectively. Sliced potato dipped in electrolyzed oxidizing water containing NaCl and citron juice for 30 minutes showed significantly low PPO activity, 64 units in treatment with NaCl and 91 units in treatment with citron juice. At the same time, changes in color value(ΔE) of sliced potato was below 3 in most treatments.

Synthesis of acrylic oligomer/graphene oxide composite with improved electromagnetic wave shield

박지현,임민지,송지은,김형일 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Graphene is used in many polymer composites due to its excellent electrical, mechanical and barrier properties. The graphene oxide has various oxygen-containing groups such as epoxide, hydroxyl and carboxyl groups. Various additives are used for various polymers to improve the physical properties of polymer, to improve the processability and the product quality, and to reduce the manufacturing cost. The acrylic oligomers of molecular weight 2000 were prepared by controlling the reaction conditions without using the chain transfer agent in order to apply as additives. Oligomers from both N-vinylpyrrolidone and butyl acrylate were prepared on the graphene oxide surface during polymerization. As a result, the acrylic oligomer/graphene oxide composite played the role of additive to improve the electromagnetic interference shielding ability of polymer.

All p-i-n hydrogenated amorphous silicon oxide thin film solar cells for semi-transparent solar cells

Yang, Johwa,Jo, Hyunjin,Choi, Soo-Won,Kang, Dong-Won,Kwon, Jung-Dae Elsevier 2018 THIN SOLID FILMS - Vol.662 No.-

<P><B>Abstract</B></P> <P>We focused on fabricating all p-i-n layer hydrogenated amorphous silicon oxide (a-SiO<SUB>x</SUB>:H) thin film solar cells in order to improve their transmittance in visible ranges of 500–800 nm for application in building integrated photovoltaics system. We varied CO<SUB>2</SUB>/SiH<SUB>4</SUB> (<I>R</I>) gas flow ratio from 0 to 0.6 for i-layer to investigate an effect of oxygen addition. When the <I>R</I> ratio increased, the transmittance of devices improved due to the enhancement in optical bandgap of the absorber. However, power conversion efficiency (PCE) decreased owing to the increase in defects and recombination rate which might be ascribed to back bonding of oxygen atoms with Si atoms. Unlike other <I>R</I> flow ratio, however, the PCE of a-SiO<SUB>x</SUB>:H solar cell at the <I>R</I> ratio of 0.2 was slightly improved by the increase in open circuit voltage as indicated by the wide band gap and the increase in quantum efficiency within short-wavelengths (300–500 nm). We introduced a figure of merit (FOM), multiplication of PCE and average transmittance in range of 500–800 nm, in order to assess the performance of transparent solar cells. The a-SiO<SUB>x</SUB>:H solar cell at the <I>R</I> ratio of 0.2 achieved the highest FOM, which was better than conventional amorphous silicon solar cell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> All p-i-n layer amorphous silicon oxide solar cells were made. </LI> <LI> CO<SUB>2</SUB>/SiH<SUB>4</SUB> ratio varied from 0 to 0.6 to find an effect of oxygen addition in absorber. </LI> <LI> An Efficiency of semitransparent solar cell increased at CO<SUB>2</SUB>/SiH<SUB>4</SUB> ratio of 0.2. </LI> <LI> Transmission of solar cells was also improved with the oxygen addition. </LI> </UL> </P>

일산화탄소 저온 산화에서 금속산화물에 담지된 금촉매의 활성에 미치는 수분첨가의 영향

안호근 ( Ho Geun Ahn ),김기중 ( Ki Joong Kim ),정민철 ( Min Chul Chung ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.6

Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/Co3O4 and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/Co3O4 catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.

Effect of Hydrocarbon Additives on SNCR DeNOx Characteristics under Oxidizing Diesel Exhaust Gas Conditions

( Changmo Nam ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.10

DeNOx experiments for the effects of hydrocarbon additives on diesel SNCR process were conducted under oxidizing diesel exhaust conditions. A diesel-fueled combustion system was set up to simulate the actual cylinder and head, exhaust pipe and combustion products, where the reducing agent NH3 and C2H6/diesel fuel additives were separately or simultaneously injected into the exhaust pipe, used as the SNCR flow reactor. A wide range of air/fuel ratios (A/F=20~40) were maintained, based on engine speeds where an initial NOx level was 530 ppm and the molar ratios (β=NH₃/NOx) ranged between 1.0~2.0, together with adjusting the amounts of hydrocarbon additives. Temperature windows were normally formed in the range of 1200~1350K, which were shifted downwards by 50~100K with injecting C₂H₆/diesel fuel additives. About 50~68% NOx reduction was possible with the above molar ratios (β) at the optimum flow #1 (T_in=1260K). Injecting a small amount of C₂H₆ or diesel fuel (γ=hydrocarbon/NOx) gave the promising results, particularly in the lower exhaust temperatures, by contributing to the sufficient production of active radicals (OH/O/HO₂/H) for NOx reduction. Unfortunately, the addition of hydrocarbons increased the concentrations of byproducts such as CO, UHC, N₂O and NO₂, and their emission levels are discussed. Among them, Injecting diesel fuel together with the primary reductant seems to be more encouraging for practical reason and could be suggested as an alternative SNCR DeNOx strategy under diesel exhaust systems, following further optimization of chemicals used for lower emission levels of byproducts.