Effect of potassium addition on bimetallic PtSn supported θ-Al₂O₃ catalyst for n-butane dehydrogenation to olefins

Nagaraja, B.M.,Jung, H.,Yang, D.R.,Jung, K.D. Elsevier Science Publishers 2014 CATALYSIS TODAY - Vol.232 No.-

PtSn/θ-Al<SUB>2</SUB>O<SUB>3</SUB> catalysts with different amount of potassium (0.4, 0.7, 0.95, 1.2 and 1.45wt.%) were prepared by an impregnation method, and their catalytic activity in n-butane dehydrogenation was investigated at 823K, an atmospheric pressure and a GHSV of 18,000mL(g<SUB>cat</SUB>h)<SUP>-1</SUP>. The compositions listed in order of n-C<SUB>4</SUB><SUP>=</SUP> yields at 823K were as follows: K<SUB>0.95</SUB>(PtSn)<SUB>1.5</SUB>>(PtSn)<SUB>1.5</SUB>>K<SUB>0.4</SUB>(PtSn)<SUB>1.5</SUB>>K<SUB>0.7</SUB>(PtSn)<SUB>1.5</SUB>>K<SUB>1.2</SUB>(PtSn)<SUB>1.5</SUB>>K<SUB>1.45</SUB>(PtSn)<SUB>1.5</SUB>>K<SUB>0.9</SUB>(Pt)<SUB>1.5</SUB>. The K<SUB>0.9</SUB>(Pt)<SUB>1.5</SUB> and K<SUB>0.95</SUB>(Sn)<SUB>1.5</SUB> catalyst severely deactivated in n-butane dehydrogenation. The (PtSn)<SUB>1.5</SUB> (without K) catalyst showed the highest n-butane conversion, while K<SUB>0.95</SUB>(PtSn)<SUB>1.5</SUB> did the highest n-C<SUB>4</SUB><SUP>=</SUP> yield. The small amount of potassium on bimetallic PtSn/θ-Al<SUB>2</SUB>O<SUB>3</SUB> catalyst improved n-C<SUB>4</SUB><SUP>=</SUP> selectivity, but slightly decreased n-butane conversion, resulting in the increase of n-C<SUB>4</SUB><SUP>=</SUP> yield. The effect of potassium was caused by blocking the acid sites of Pt catalyst. The TPR and HAADF STEM-EDS study suggested the reduction procedure of the Pt, Sn and K species. However, the higher loaded potassium (1.2 and 1.45wt.%) doped (PtSn)<SUB>1.5</SUB> catalysts were rather highly deactivated because the sizes of Pt particles were increased by weakening the interaction between Pt and Sn. The n-C<SUB>4</SUB><SUP>=</SUP> selectivity of the (PtSn)<SUB>1.5</SUB> catalyst increased with respect to the reaction, while that of the potassium doped catalysts maintained the high n-C<SUB>4</SUB><SUP>=</SUP> selectivity from the beginning of the reaction. Also, different alkali metals (Ca, Na and Li) were tested for the comparison with K. The potassium doped catalyst showed the highest n-C<SUB>4</SUB><SUP>=</SUP> yield among the other alkali metals for n-butane dehydrogenation.

H형강 롤포스 예측 모델 개발

정현석(H. S. Jung),위창현(C. H. Wee),문홍길(H. K. Moon),서경호(K. H. Seo),김태형(T. H. Kim),배병철(B. C. Bae),이영석(Y. S. Lee) 한국소성·가공학회 2023 한국소성가공학회 학술대회 논문집 Vol.2023 No.11

Conversion of organic solid waste to hydrogen and methane by two-stage fermentation system with reuse of methane fermenter effluent as diluting water in hydrogen fermentation

Jung, K.W.,Moon, C.,Cho, S.K.,Kim, S.H.,Shin, H.S.,Kim, D.H. Elsevier Applied Science 2013 Bioresource technology Vol.139 No.-

In this study, a two-stage system converting organic solid waste (food waste+sewage sludge) to H<SUB>2</SUB> and CH<SUB>4</SUB> was operated. In the first stage of dark fermentative hydrogen production (DFHP), a recently proposed method that does not require external inoculum, was applied. In the second stage, anaerobic sequencing batch reactor (ASBR) and an up-flow anaerobic sludge blanket reactor (UASBr) were followed to treat H<SUB>2</SUB> fermenter effluent. (H<SUB>2</SUB>+CH<SUB>4</SUB>-ASBR) system showed better performance in terms of total biogas conversion (78.6%), while higher biogas production rate (2.03L H<SUB>2</SUB>/L<SUB>system</SUB>/d, 1.96L CH<SUB>4</SUB>/L<SUB>system</SUB>/d) was achieved in (H<SUB>2</SUB>+CH<SUB>4</SUB>-UASBr) system. To reduce the alkali addition requirement in DFHP process, CH<SUB>4</SUB> fermenter effluent was tested as a diluting water. Both the ASBR and UASBr effluent was effective to keep the pH above 6 without CH<SUB>4</SUB> production. In case of using ASBR effluent, H<SUB>2</SUB> production dropped by 15%, but alkali addition requirement was reduced by 50%.

Rapid formation of hydrogen-producing granules in an up-flow anaerobic sludge blanket reactor coupled with high-rate recirculation

Jung, K.W.,Cho, S.K.,Yun, Y.M.,Shin, H.S.,Kim, D.H. Pergamon Press ; Elsevier Science Ltd 2013 International journal of hydrogen energy Vol.38 No.22

Application of an up-flow anaerobic sludge blanket (UASB) reactor to dark fermentative H<SUB>2</SUB> production greatly improves H<SUB>2</SUB> productivity due to the maintenance of high biomass concentration. However, a long start-up HRT and start-up period are required to develop the H<SUB>2</SUB>-producing granules (HPGs) and to avoid washing out the suspended sludge at the start of the process. In the present work, a novel strategy to rapidly form HPGs was developed in UASB reactor. To induce highly active mass transfer in the UASB reactor, a high recirculation rate (15 times the influent) was adopted over 10 days, then recirculation was stopped. As the operation progressed, self-flocculation took place and HPGs developed after 90 h of operation. A stable production of H<SUB>2</SUB> was observed after 20 days of operation. The thickness of the HPGs layer in the sole UASB reactor increased progressively, and consequently the average HPG diameter and concentration were 1.86 mm (0.1-3.9 mm) and 52 g/L, respectively, after 60 days of operation. These findings seem to suggest that high-rate recirculation plays a crucial role in accelerating the formation of HPGs in such UASB reactors through high up-flow velocity, providing active mass transfer.

Ex situ catalytic upgrading of lignocellulosic biomass components over vanadium contained H-MCM-41 catalysts

Kim, B.S.,Jeong, C.S.,Kim, J.M.,Park, S.B.,Park, S.H.,Jeon, J.K.,Jung, S.C.,Kim, S.C.,Park, Y.K. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.265 No.-

<P>H-V-MCM-41 catalysts containing 5, 10, and 30 wt% of vanadium were synthesized and applied to the ex situ catalytic pyrolysis (CP) of three polymeric components of lignocellulosic biomass for the first time. Characterization of the catalysts was performed using N-2 adsorption-desorption, XRD, FT-IR, and NH3-TPD. The results of XRD analysis showed that 5 wt% and 10 wt% H-V-MCM-41 catalysts maintained the mesoporous structure, whereas the mesoporous structure was destroyed in 30 wt% H-V-MCM-41 with considerable amount of small V2O5 crystalline outside the framework. NH3-TPD showed that H-V-MCM-41 has mostly weak acid sites and that 10 wt% H-V-MCM-41 had the largest quantity of acid sites due to framework vanadium. In the case of CP of cellulose using Py-GC/MS, 10 wt% H-V-MCM-41 showed the highest catalytic activity for the production of valuable furanic compounds such as furfural because of the enhanced deoxygenation over the acid sites formed on framework vanadium. In the case of CP of xylan as well, 10 wt% H-V-MCM-41 led to the largest yield of mono-aromatics. The production of acetic acid was also promoted by H-V-MCM-41 catalysts. The CP of lignin over H-V-MCM-41 catalysts promoted substantially the production of important feedstock chemicals for the petrochemical industry: phenolics and mono-aromatics. (C) 2015 Elsevier B.V. All rights reserved.</P>

Optimization of combined (acid + thermal) pretreatment for fermentative hydrogen production from Laminaria japonica using response surface methodology (RSM)

Jung, K.W.,Kim, D.H.,Kim, H.W.,Shin, H.S. Pergamon Press ; Elsevier Science Ltd 2011 International journal of hydrogen energy Vol.36 No.16

In the present work, a combined (acid + thermal) pretreatment was applied for the enhanced fermentative H<SUB>2</SUB> production (FHP) from Laminaria japonica. Various pretreatment conditions including HCl concentrations, heating temperatures, and reaction times were optimized via response surface methodology (RSM) with a Box-Behnken design (BBD). Through regression analysis, it was found that H<SUB>2</SUB> yield was well fitted by a quadratic polynomial equation (R<SUP>2</SUP> = 0.97), and the HCl concentration was the most significant factor influencing FHP. The desirable pretreatment conditions found were HCl concentration of 4.8%, temperature of 93 <SUP>o</SUP>C, and reaction time of 23 min, under which H<SUB>2</SUB> yield reached to 159.6 mL H<SUB>2</SUB>/g dry cell weight (dcw). The main organic acids produced were acetic and butyric acids that related closely with H<SUB>2</SUB> production. The concentration of hydroxymethylfurfural (HMF), a byproduct formed during the pretreatment process, showed an inverse relationship with H<SUB>2</SUB> yield, indicating that pretreatment conditions for the H<SUB>2</SUB> production from L. japonica were successfully optimized, by increasing the hydrolysis rate of the feedstock and also reducing the formation of HMF.

Experimental infection of mandarin duck with highly pathogenic avian influenza A (H5N8 and H5N1) viruses

Kang, H.M.,Lee, E.K.,Song, B.M.,Heo, G.B.,Jung, J.,Jang, I.,Bae, Y.C.,Jung, S.C.,Lee, Y.J. Elsevier Scientific Pub. Co 2017 Veterinary microbiology Vol.198 No.-

<P>A highly pathogenic avian influenza (HPAI) H5N8 virus was first detected in poultry and wild birds in South Korea in January 2014. Here, we determined the pathogenicity and transmissibility of three different clades of 1-15 viruses in mandarin ducks to examine the potential for wild bird infection. H5N8 (Glade 2.3.4.4) replicated more efficiently in the upper and lower respiratory tract of mandarin ducks than two previously identified H5N1 virus clades (clades 2.2 and 2.3.2.1). However, none of the mandarin ducks infected with H5N8 and H5N1 viruses showed severe clinical signs or mortality, and gross lesions were only observed in a few tissues. Viral replication and shedding were greater in H5N8-infected ducks than in H5N1-infected ducks. Recovery of all viruses from control duck in contact with infected ducks indicated that the highly pathogenic H5 viruses spread horizontally through contact. Taken together, these results suggest that H5N8 viruses spread efficiently in mandarin ducks. Further studies of pathogenicity in wild birds are required to examine possible long-distance dissemination via migration routes. (C) 2016 Elsevier B.V. All rights reserved.</P>

Eugenol Inhibits K⁺ Currents in Trigeminal Ganglion Neurons

Li, H. Y.,Park, C.-K.,Jung, S. J.,Choi, S.-Y.,Lee, S. J.,Park, K.,Kim, J. S.,Oh, S. B. SAGE Publications 2007 Journal of dental research Vol.86 No.9

<P>Eugenol, a natural capsaicin congener, is widely used in dentistry. Eugenol inhibits voltage-activated Na<SUP>+</SUP> and Ca<SUP>2+</SUP> channels in a transient receptor potential vanilloid 1 (TRPV1)-independent manner. We hypothesized that eugenol also inhibits voltage-gated K<SUP>+</SUP> currents, and investigated this in rat trigeminal ganglion neurons and in a heterologous system using whole-cell patch clamping. Eugenol inhibited voltage-gated K<SUP>+</SUP> currents, and the inhibitory effects of eugenol were observed in both capsaicin-sensitive and capsaicin-insensitive neurons. Pre-treatment with capsazepine, a well-known antagonist of TRPV1, failed to block the inhibitory effects of eugenol on K<SUP>+</SUP> currents, suggesting no involvement of TRPV1. Eugenol inhibited human Kv1.5 currents stably expressed in <I>Ltk</I><SUP>−</SUP> cells, where TRPV1 is not endogenously expressed. We conclude that eugenol inhibits voltage-gated K<SUP>+</SUP> currents in a TRPV1-independent manner. The inhibition of voltage-gated K<SUP>+</SUP> currents is likely to contribute to the irritable action of eugenol. Abbreviations: human Kv1.5 channel, hKv1.5; transient receptor potential vanilloid 1, TRPV1.</P>

Catalytic properties of microporous zeolites in the synthesis of octyl glucoside from D-glucose with 1-octanol by single-step direct glucosidation

Chung, K.H.,Lee, S.J.,Lee, H.,Kim, H.,Park, Y.K.,Kim, B.H.,Jung, S.C. Elsevier 2016 Microporous and mesoporous materials Vol.233 No.-

<P>Catalytic properties of various microporous zeolites consisted of different acidic properties and pore topologies were studied in the synthesis of octyl glucoside from D-glucose with 1-octanol by single-step direct glucosidation. The influences of acidic properties and pore topologies of the zeolite catalysts were evaluated relating to the conversion of glucose and selectivities of octyl glucosides. The octyl glucosides could be synthesized conveniently by the single-step direct glucosidation through aging of reactants without further pre-treatment or additional supply of reactant. The reusability of the zeolite catalyst was evaluated to the used zeolite. The high conversion of D-glucose was obtained on H+ ion exchanged FAU (H-FAU) zeolite which has a mild acid strength. The conversion and yield were improved with increasing of acid site amount of the zeolite catalysts. H-FAU zeolite catalysts exhibited high octyl glucopyranoside selectivity owing to relatively a large pore cavity and a high concentration of mild acid sites. The selectivities of the octyl glucoside isomers were mainly depended on the differences of pore structure and concentration of acid sites of the zeolite catalysts. The zeolite used in the reaction was able to reuse through the regeneration process. (C) 2016 Elsevier Inc. All rights reserved.</P>

플랜지가 있는 제품에서 부분패드의 영향에 관한 연구

고관영,허주환,문정효,장재석,김동윤,정민섭,김주찬,박기용,이강연,조명우,이권진,조영호,이효걸,김주호,이경희 울산과학대학 2000 연구논문집 Vol.27 No.1

본 논문에서는 기존의 Motion-JPEG 기반 감시시스템에서 낮은 동영상 압축성능 문제를 해결하기 위한 새로운 동영상 압축기법을 제안하였다. 제안된 방법에서는 현재 프레임의 JPEG 데이터 중 변화된 압축 데이터만이 실시간으로 추출하고 저장된다. 제안된 방법에 의해 저장된 데이터는 기존의 JPEG과는 다른 고유의 포맷을 가지기 때문에, 동영상 데이터는 더욱 안전하게 유지될 수 있다. 실험을 통해, 제안된 동영상 압축기법의 압축률이 기존의 Motion-JPEG 기반 감시시스템에 비해 3배정도 높다는 것을 확인할 수 있었다.