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Enhanced photocatalytic activity of TiO2/Ca12Al14O33 in NO removal
박지혜,Hong Min Woo,Oo Wathone,Park Jung Joon,Park Hee Ju,이광복 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12
TiO2 supported on Ca12Al14O33 (Mayenite) was synthesized and investigated for use as a photocatalytic concrete material. TiO2/Mayenite (TiO2/M) catalysts were prepared with varying TiO2 loading amounts (1–20 wt%). The photocatalytic activity of the catalysts was measured using the ISO standard NO removal test. TiO2/M catalysts exhibited significantly enhanced photocatalytic activities compared to pure TiO2, with the NO removal efficiency increasing as TiO2 loading increased up to 10 wt% and then decreasing with further loading of TiO2. The NO removal rate of the TiO2/M catalyst, which contained 10 wt% TiO2, was 8.72 µmol (equivalent to 350 µmol/m2·h). X-ray photoelectron spectroscopy (XPS) analysis suggested that oxygen on the TiO2/M catalysts with low TiO2 loading exists in the form of Ti−OH rather than TiO2. This study focuses on the formation of Ti−OH on the catalyst surface, which is promoted by the unique crystal structure of Mayenite that supplies oxygen ions and electrons to the TiO2 layer. The NO removal efficiency of the catalysts was found to be dependent on the interaction between TiO2 and Mayenite. Overall, this study demonstrates the potential of TiO2/Mayenite for use as a highly effective photocatalytic concrete material, with the unique properties of the Mayenite support playing a critical role in enhancing the photocatalytic activity of the catalyst.
Effects of Mg Addition to Cu/Al2O3 Catalyst for Low-Temperature Water Gas Shift (LT-WGS) Reaction
Zakia Akter Sonia,Ji Hye Park,Wathone Oo,Kwang Bok Yi 한국청정기술학회 2023 청정기술 Vol.29 No.1
To investigate the effects of Mg addition at different aging times and temperatures, Cu/MgO/Al2O3 catalysts were synthesized for the low-temperature water gas shift (LT-WGS) reaction. The co-precipitation method was employed to prepare the catalysts with a fixed Cu amount of 30 mol% and varied amounts of Mg/Al. Synthesized catalysts were characterized using XRD, BET, and H2-TPR analysis. Among the prepared catalysts, the highest CO conversion was achieved by the Cu/MgO/Al2O3 catalyst (30/40/30 mol%) with a 60 oC aging temperature and a 24 h aging time under a CO2-rich feed gas. Due to it having the lowest reduction temperature and a good dispersion of CuO, the catalyst exhibited around 65% CO conversion with a gas hourly space velocity (GHSV) of 14,089 h-1 at 300 oC. However, it has been noted that aging temperatures greater or less than 60 oC and aging times longer than 24 h had an adverse impact, resulting in a lower surface area and a higher reduction temperature bulk-CuO phase, leading to lower catalytic activity. The main findings of this study confirmed that one of the main factors determining catalytic activity is the ease of reducibility in the absence of bulk-like CuO species. Finally, the long-term test revealed that the catalytic activity and stability remained constant under a high concentration of CO2 in the feed gas for 19 h with an average CO conversion of 61.83%.
Analysis of preservative ability of chitosan on CO adsorption of CuCl-alumina-based composites
May Zaw Win,박지혜,Htet Htet Naing,홍민우,Wathone Oo,이광복 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-
A common problem encountered in the utilization of CuCl-based CO adsorbents was the oxidation tendencyof CuCl under atmospheric conditions, with a rapid decrease in an initial CO adsorption uptake overthe storage period. In this work, chitosan-modified CuCl-alumina-based composites were prepared by awet-impregnation method followed by N2 calcination. With the chitosan to alumina weight ratio of 0.15,the resultant fresh composite named 30Cu-0.15chi-Al (30 wt% Cu+/chitosan impregnated alumina) gavethe highest initial CO adsorption uptake (19 cm3/g) among the analyzed samples. Interestingly, this compositealso preserved its initial CO adsorption uptake throughout the 30-day air-exposed storage owing tothe antioxidant effect of the stable Cu-CN constituted organometallic complexes which had been developedon the composite surface during the calcination step. These Cu complex clusters constructed theoxygen-resistant shield for the doped CuCl which was well dispersed inside the porous structure, as confirmedthrough the analysis of SEM, EDS and XPS. Besides, this sample achieved a higher CO selectivityfactor (5.2) over CO2 because of the CO affinity of Cu1+ions by p complexation reaction. This study pointedout a stably efficient CO adsorbent modified with chitosan, which has a great potential to be industrialremediation of CO pollution.