Preparation of Ba-doped TiO₂ hollow sphere and their performance in water electrolysis

Jayeeta Chattopadhyay,Jun Cheol Lee,Jae Ek Son,Daewon Pak 한국에너지공학회 2009 한국에너지공학회 학술발표회 Vol.2009 No.9

Preparation and characterizations of Ni-alumina, Ni-ceria and Ni-alumina/ceria catalysts and their performance in biomass pyrolysis

Jayeeta Chattopadhyay,박대원,Jae Ek Son 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.8

The catalytic activity of Ni/Al2O3, Ni/CeO2, and Ni/Al_2O_3-CeO_2 catalysts of different compositions were investigated over biomass pyrolysis process. Catalysts were prepared using co-precipitation method with various compositions of nickel and support materials. Surface characterizations of the materials were evaluated using XRD, SEM,and BET surface area analysis with N_2 adsorption isotherm. XRD analysis reveals the presence of Al_2O_3, CeO_2, NiO,and NiAl_2O_4 phases in the catalysts. Paper samples used for daily writing purposes were chosen as biomass source in pyrolysis. TGA experiment was performed on biomass with and without presence of catalysts, which resulted in the decrease of initial degradation temperature of paper biomass with the influence of catalysts. In a fixed-bed reactor, untreated and catalyst mixed biomasses were pyrolyzed up to 800℃ , with a residence time of 15 min. The non-condensable gases were collected through gas bags every after 100 ℃ and also at 5, 10, and 15 min residence time at 800 ℃, which were analyzed using TCD-GC equipment. Comparative distributions of solid, liquid and gaseous components were made. Results indicated diminished amount of tar production in presence of catalysts. 30 wt% Ni/CeO-2 catalyst yielded least amount of tar product. The least amount of CO was produced over the same catalyst. According to gas analysis result, 30 wt% Ni doped alumina sample produced maximum amount of H_2 production with 43.5 vol% at 800℃ (15min residence time).

Thermogravimetric characteristics and kinetic study of biomass co-pyrolysis with plastics

Jayeeta Chattopadhyay,김철호,김래현,박대원 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.5

The pyrolysis of pure biomass, high density polyethylene (HDPE), polypropylene (PP) and polyethylene terephthalate (PET), plastic mixtures [HDPE+PP+PET (1 : 1 : 1)], and biomass/plastic mixture (9 : 1, 3 : 1, 1 : 1, 1 : 3 and 1 : 9) were investigated by using a thermogravimetric analyzer under a heating rate at 10 oC/min from room temperature to 800 oC. Paper was selected as the biomass sample. Results obtained from this comprehensive investigation indicated that biomass was decomposed mainly in the temperature range of 290-420 oC, whereas thermal degradation temperature of plastic mixture is 390-550 oC. The percentage weight loss difference (W) between experimental and theoretical ones was calculated, which reached a significantly high value of (−)15 to (−)50% at around 450 oC in various blend materials. These thermogravimetric results indicate the presence of significant interaction and synergistic effect between biomass and plastic mixtures during their co-pyrolysis at the high temperature region. With increase in the amount of plastic mixture in blend material, the char production has diminished at final pyrolysis temperature range. Additionally, a kinetic analysis was performed to fit with TGA data, the entire pyrolysis processes being considered as one or two consecutive first order reactions.

Thermogravimetric study on pyrolysis of biomass with Cu/Al2O3 catalysts

Jayeeta Chattopadhyay,Chulho Kim,Raehyun Kim,박대원 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.1

The Cu/Al2O3 catalysts of three different compositions (10, 20 and 30 wt.% Cu loading), have been investigated with regard to their catalytic effects on pyrolysis of paper biomass species (up to 800℃) by thermogravimetric analysis (TGA) experiments. The results show that catalysts made devolatilization at lower (below200℃) and middle temperature (200–400℃) regions in the pyrolysis of the biomass species, and the temperature reduction effects follow the order: 30 > 20 > 10 wt.% copper loading. Although the catalysts with 10 and 20 wt.% copper have shown almost similar activity, whereas dehydration reaction was enhanced almost 40% in the presence of 30 wt.% copper-loaded catalyst. At the same time, the amount of residue at theendof the reactionalso decreasedwithincrease inthe copper loading from10 to30 wt.%. At higher temperatures (above 400℃), the catalyst with greater copper loaded worked more nicely possibly due to the enhancement of the depolymerization reactionoverdehydration of cellulose in presence ofmore basic catalysts. The catalysts were characterized by using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis and scanning electron microscopy (SEM).XRDresults showthe formation of CuAl2O4 spinel and Cu2O phase in the catalysts. .

Electrochemical performance of Ni/TiO2 hollow sphere in proton exchange membrane water electrolyzers system

Jayeeta Chattopadhyay,Rohit Srivastava,Prem Kumar Srivastava 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.8

This work presents the electrocatalytic evaluation of Ni/TiO2 hollow sphere materials in PEM water electrolysis cell. All the electrocatalysts have shown remarkably enhanced electrocatalytic properties in comparison with their performance in aqueous electrolysis cell. According to cyclic voltammetric results, 0.36 A cm−2 peak current density has been exhibited in hydrogen evolution reaction (HER) from 30 wt% Ni/TiO2 electrocatalyst. 15 wt% Ni-doped titania sample has shown the best result in oxygen evolution reaction (OER) with the anodic peak current density of 0.3 A cm−2. In the anodic polarization curves, the performance of 15 wt% Ni/TiO2 hollow sphere electrocatalyst was evaluated up to 140 mA cm−2 at comparatively lower over-potential value. 20 wt% Ni/TiO2 hollow sphere electrocatalyst has also shown electrochemical stability in PEM water electrolyzer for 48 h long analysis. The comparative electrocatalytic behavior of hollow spherical materials with non-sphericals is also presented, which clearly shows the influence of hollow spherical structure in greater electrocatalytic activity of the materials. The physical characterization of all the hollow spherical materials is presented in this work, which has confirmed their better electrochemical behavior in PEM water electrolyzer.

Metal hollow sphere electrocatalysts

Jayeeta Chattopadhyay,Tara Sankar Pathak,Daewon Pak,Rohit Srivastava 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.5

Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions.

Performance of tin doped titania hollow spheres as electrocatalysts for hydrogen and oxygen production in water electrolysis

Chattopadhyay, Jayeeta,Rok Kim, Hong,Bong Moon, Sang,Pak, Daewon Elsevier 2008 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.33 No.13

<P><B>Abstract</B></P><P>The electrocatalytic activity of tin doped TiO<SUB>2</SUB> hollow sphere particles has been examined in acid solution. Titania hollow spheres have been synthesized by using poly(styrene-methacrylic acid) latex particles as a template, and tin was doped over spheres with the appropriate amount of SnCl<SUB>2</SUB>·2H<SUB>2</SUB>O solution in HCl. The surface characteristics have been evaluated by XRD, SEM and TEM analysis. XRD analysis has shown the presence of rutile SnO<SUB>2</SUB> and TiO<SUB>2</SUB> phase in the catalysts; and the peak intensity for SnO<SUB>2</SUB> phase increased with rise in the calcination temperature indicating the critical growth of tin on the surface of the catalysts. Diameter of pure TiO<SUB>2</SUB> hollow spheres and Sn doped samples were found from SEM and TEM images in the range of 1–1.2 and 0.4–0.6μm, respectively. TGA has been performed with the uncalcined 40wt% Sn doped TiO<SUB>2</SUB> catalyst. The peaks for hydrogen and oxygen production are present significantly for all the hollow sphere samples in cyclic voltammograms; but peaks for hydrogen production is more prominent in 20 and 40wt% Sn/TiO<SUB>2</SUB> catalysts. The performances of the hollow sphere electrocatalysts were evaluated up to current densities of 50mAcm<SUP>−2</SUP> during anodic polarization measurement. Sn/TiO<SUB>2</SUB> electrocatalysts have also shown long time electrochemical stability in acidic media.</P>

Catalytic pyrolysis of biomass for production of hydrogen rich gases

차토패드히야 제이타(Jayeeta Chattopadhyay),최용근(Yong Keun Choi),손재익(Jae Ek Son),박대원(Daewon Pak) 한국에너지학회 2007 한국에너지공학회 학술발표회 Vol.2007 No.-

Pt/TiO₂ Hollow sphere의 제조와 전기화학적 특성

김홍록,( Chattopadhyay Jayeeta ),한희중,박대원 한국공업화학회 2007 한국공업화학회 연구논문 초록집 Vol.2007 No.-

Preparation of platinum-doped hollow spheres and their electrocatalytic activity in water electrolysis

박대원,Hong Rok Kim,Jayeeta Chattopadhyay,Jae Ik Son 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

Pure TiO2 hollow spheres were prepared by using poly(styrene-methacrylic acid) latex particles as template; thereafter, titania hollow spheres were coated by platinum with an appropriate amount of choloroplatinic acid solution to obtain Pt/TiO2 catalysts. The morphology and structure of nonstructural Pt/TiO2 hollow spheres were characterized by BET, XRD, TGA, SEM and TEM analysis. In the samples, a remarkably uniform layer of Pt consisting of particles from 5 to 70 nm in size was formed over TiO2 hollow spheres. We found the electrocatalytic nature of the samples by cyclic voltammetric experiment in acidic solution. The anodic peak current density of 20 wt% Pt-loaded TiO2 hollow particles was observed 2.5 times higher than that of 5 wt% Pt/TiO2 in the same experimental condition. Also, the anodic current density of 20 wt% Pt/TiO2 hollow spheres calcined at various temperatures followed the order: 400 oC≈500 oC>600 oC. The electrocatalytic activity of the Pt-loaded TiO2 hollow spheres depends on the amount of atomic platinum present in the sample; a higher concentration of platinum results in a larger current density value in anodic sweep, resulting in more oxygen production during electrolysis. Pt/TiO2 hollow sphere catalysts have also shown long term electrocatalytic stability in acidic media.