Research Article Modification of One-Dimensional TiO ...downloads.hindawi.com/journals/ijp/2014/471713.pdf · Research Article Modification of One-Dimensional TiO 2 Nanotubes with

Research ArticleModification of One-Dimensional TiO2 Nanotubes withCaO Dopants for High CO2 Adsorption

Chin Wei Lai

Nanotechnology amp Catalysis Research Centre (NANOCAT) Institute of Postgraduate Studies (IPS) Universiti Malaya 3rd FloorBlock A 50603 Kuala Lumpur Malaysia

Correspondence should be addressed to Chin Wei Lai cwlaiumedumy

Received 30 January 2014 Revised 21 February 2014 Accepted 21 February 2014 Published 26 March 2014

Academic Editor Tian-Yi Ma

Copyright copy 2014 Chin Wei LaiThis is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

One-dimensional calcium oxide (CaO-) based titanium dioxide (TiO2) nanotubes were successfully synthesized through a rapid

electrochemical anodization and chemicalwet impregnation techniques In this study calciumnitrate solutionwas used as a calciumsource precursorThe reaction time and concentration of calcium source on the formation ofCaO-TiO

2nanotubeswere investigated

using field emission microscopy energy dispersion X-ray spectroscopy and X-ray diffractionThe adsorption capacity of CO2was

determined by thermal gravimetric analyzer A maximum of 445mmolg was achieved from the CaO-TiO2nanotubes (664 at

of Ca) The finding was attributed to the higher active surface area for CaO to adsorb more CO2gas and then formed CaCO

3

compound during cyclic carbonation-calcination reaction

1 Introduction

Recently solid CO2adsorbents are used as an alternative

and potentially less-energy-intensive separation technol-ogy These CO

2adsorbents can be utilized from ambient

temperature up to 973K by yielding less waste duringcycle In addition their waste can be disposed of withoutundue environmental precautions as compared to liquidadsorbent [1] A variety of solid physical adsorbents havebeen considered for CO

2capture including microporous

and mesoporous materials (carbon-based sorbents such asactivated carbon and carbon molecular sieves zeolites andchemically modified mesoporous materials) metal oxidesand hydrotalcite-like compounds [2 3] These listed adsor-bents usually can be classified into three types based ontheir sorptiondesorption temperatures (1) low temperatureadsorbent lt473K (carbon zeolites MOFsZIFs alkali metalcarbonates and amine-based materials) (2) intermediatetemperature adsorbent 473ndash673K (hydrotalcite-like com-pounds HTLcslayered double hydroxides LDHs) and (3)high-temperature adsorbents gt673K (calcium based andalkali ceramic) The summary of those adsorbents with theirefficiency and operating parameters are shown in Table 1

According toTable 1 CaO and alkali ceramics are promis-ing candidates for CO

2adsorption Therefore CaO-based

adsorbent has gained great attention due to its great capability(116mmolg) as compared to other adsorbents in capturingCO2gases through cyclic carbonation-calcination reaction

In addition CaO-based adsorbent has high reactivity withCO2gases high capacity and low material cost [4] The car-

bonation temperature for CaO-based adsorbents is between873 and 973K and their regeneration temperature is normallyabove 1223K The reversible reaction between CaO and CO

2

isCaO (s) + CO

2(g) 999445999468 CaCO

3(s)

Δ119867∘

87315K = minus1712 kJ molminus1 (for carbonation)(1)

In this manner nanocrystalline of CaO has been provento be useful in the noncatalytic removal of CO

2inH2produc-

tion [5] The nanocrystalline of CaO with vacanciesdefectswhich often related to the presence of basic and acidicsites within their lattice The structural defects normally areinvolved in the basic-acidic catalytic reactions It is a well-known fact that CaO has highly reactive and strong basicsites because of the isolated O2minus centers as well as weak

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2014 Article ID 471713 9 pageshttpdxdoiorg1011552014471713

2 International Journal of Photoenergy

Table 1 The different types of solid CO2 adsorbents based on their sorptiondesorption temperatures

Adsorbent Total capacity(mmolg)

Temperature(K)

Pressure(atm) Reference

Low temperature adsorbentsAmine based

Amine-modified mesoporous silica 45 348 1 (Liu et al 2010) [12]Amine-modified ordered mesoporous silica (OMS) 15 mdash mdash (Zelenak et al 2008) [13]Amine-modified OMSs 02ndash14 348 1 (Liu et al 2010) [12]Amine tetraethylenepentamine (TEPA)OMSs 46 348 1 (Liu et al 2010) [12]

MOFsZIFsMOF-2 32 mdash 41 (Millward and Yaghi 2005) [14]

Carbonactivated carbon basedCoal-based activated carbon 03 323 0001 (Deng et al 2011) [15]Porous carbon nitride (CN) 290 298 mdash (Li et al 2010) [16]N-doped carbons template from zeolite 69 273 1 (Xia et al 2011) [17]Activated carbonN2 375

293 1 (Zhang et al 2010) [18]Activated carbonH2 349Activated carbonNH3 322Activated carbon 15 303 40 (Drage et al 2009) [19]Activated carbon 35 275 1 (Wang et al 2008) [20]Carbon nanotubes (CNTs)3-aminopropyltriethoxysilane(APTS) 245 323 mdash (Su et al 2011) [21]

Alumina based120574-Al2O3 031 295 mdash (Rege and Yang 2001) [22]

Zeolite basedY-type zeolitetetraethyl-enepentamine (TEPA) 427 303ndash333 (Su et al 2010) [23]Natural zeolite 205

298 01 (Ertan and Cakicioglu-Ozkan2005) [24]

Treated zeoliteH3PO4 195Synthetic zeolite-5X 549Synthetic zeolite-13A 682LilSX 017

mdash 1 (Brandani and Ruthven 2004) [25]NaLX 023CaX 02413X (NaX) 294 295 mdash (Rege and Yang 2001) [22]

Magnesium basedMgOAl2O3 136 333 1 (Li et al 2010) [26]

Intermediate temperature adsorbentsLDH

Mg-Al-CO3 LDHs 049 473 005 (Ram Reddy et al 2006) [27]High temperature adsorbents

Lithium orthosilicatesLi4SiO4 614 773 1 (Kato et al 2002) [28]

Lithium zirconatesLi2ZrO3 455 773 1 (Ida and Lin 2003) [29]

Li2ZrO3 450 823 1 (Ochoa-Fernandez et al 2005)[30]

Li2ZrO3 (nanocrystalline) 614 848 1 (Ochoa-Fernandez et al 2006)[31]

International Journal of Photoenergy 3

Table 1 Continued


Temperature(K)


Calcium oxide basedCaO 23 923 mdash (Satrio et al 2005) [32]CaOAl2O3 116 923 mdash (Li et al 2006) [33]CsCaO 49

723 04 (Reddy and Smirniotis 2004)[34]

RbCaO 45KCaO 38NaCaO 31CaCO3 15 573 1 (Kuramoto et al 2003) [35]CaOAl2O3 602 923 1 (Wu et al 2007) [36]Nano CaOAl2O3 602 650 mdash (Wu et al 2008) [37]

200nm

(a)

200nm

(b)

200nm

(c)

Figure 1 FESEM top view image of nanotubes subjected to wet impregnation of 06M calcium nitrate solution for (a) 24 hours (b) 48 hoursand (c) 72 hours and subsequent annealing at 673K in Ar gas for 4 hours

residual OH groups which appear when mixed with the rareearths [6] However these CO

2adsorbents suffer severely

from textural degradation during the sorptiondesorptionoperations These CO

2adsorbents can only run several tens

of cycles before any obvious degradation and are still farfrom practical applications [3] Instantly the conversion ofCaO decreased sharply from 70 in the first cycle to 20

in the eleventh cycle when tested in fluidized bed [7] Thedeactivation primarily results from the formation of thicklayer structured from CaCO

3surrounding the CaO which

severely hinders the diffusion of CO2gas to react with

the inner core Besides it has also been reported that theadsorption capacity for CaO-based sorbents decays as afunction of the sintering of CaO grain at high temperature


214

171

128

85

42

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

247

198

148

99

49

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

117

94

70

47

23

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)

Figure 2 EDX spectra of nanotubes subjected to wet impregnation of 06M calcium nitrate solution for (a) 24 hours (b) 48 hours and(c) 72 hours (all EDX spectrums are noneditable format based on our FESEM-EDX system)

and a certain loss in the porosity When pores smaller than acritical value (eg 200 nm) are filled the reaction gets muchslower [8] Therefore great efforts have to be made in orderto further improve the cyclic stability of CaO-based sorbents

One of the most promising solutions to improve thecyclic stability of CaO is controlling their architecture intoone-dimensional nanomaterials The main reason might beattributed to the fast reaction (chemical reaction) and theslow reaction (diffusion controlled) could be achieved duringCO2adsorption In this case the diffusion of CO

2into

the particle interior to react with Ca dopants could beprevented and the whole CO

2adsorption process could then

be diffusion-controlled [2 3] Theoretically the small parti-cles size of sorbent (eg 30ndash50 nm) would perform bettercarbonation-calcination reaction which allowed carbonationto take place at the rapid reaction-controlled regime Anotherpromising solution to improve cyclic stability is to incorpo-rate high stability metal oxide (titanium dioxide) into CaOparticlesTheprevention ofCaOoxidation during calcinationstage could be expected Therefore detail investigation onone-dimensional CaO-TiO

2nanotubes for effective CO

2

adsorption will be discussed

2 Experimental Procedure

One-dimensional TiO2nanotube arrays were synthesized

using a rapid-anodic oxidation electrochemical anodizationtechnique A high purity of Ti foil (996 Strem Chemical

USA) with a thickness of 127 120583m was selected as substrateto grow TiO

2nanotubes This process was conducted in a

bath with electrolytes composed of ethylene glycol (C2H6O2

gt995 Merck USA) 5 wt ammonium fluoride (NH4F

98 Merck USA) and 5wt hydrogen peroxide (H2O2

30 H2O2and 70 H

2O J T Baker USA) for 60 minutes

at 60V This experimental condition was selected because itfavors the formation of well-aligned TiO

2nanotube arrays

[9 10] After the anodization process as-anodized sampleswere cleaned using distilled water and dried under a nitrogenstream CaO-TiO

2nanotubes were then prepared through

wet impregnation technique using calcium nitrate tetrahy-drate (Ca(NO

3)2sdot4H2O Merck USA) as the precursor This

was an ex situ approach that was used to incorporate Ca2+ions into TiO

2nanotubes Two different concentrations

of calcium nitrate tetrahydrate solution (06 12M) wereprepared at different reaction times (24 48 72 hours) in awater bath of 80∘C Subsequently the samples were thermal-annealed at 673K in an argon atmosphere for 4 h in order toproduce crystalline TiO

2nanotubes

The surface morphologies of the synthesized sampleswere observed through field emission scanning electronmicroscopy (FESEM) using a Zeiss SUPRA 35VP whichis operated at a working distance of 1mm and 5 kV Theenergy dispersive X-ray spectroscopy (EDX) was appliedto elemental analysis of the CaO-TiO

2nanotubes sorbents

which is equipped in the FESEM The structural variationsand phase determination for CaO-TiO

2nanotubes sorbents


200nm

(a)

200nm

(b)

200nm

(c)


were determined using a Philips PW 1729 X-ray diffraction(XRD) which operated at 45 kV and 40mV patterns Thethermogravimetric analysis (TGA) was used to investigatethe CO

2adsorption for CaO-TiO

2nanotubes sorbents (STA

6000 Perkin Elmer USA)The steps included are N2gas flow

at a rate of 10∘Cmin from room temperature to 673K andthen holding for 30min in CO

2and finally cooling down to

573K byN2gas In the present study carbonation-calcination

reaction is set to be 673K because nanotubular structure canbe collapsed at high temperature (above 773K) [11]

3 Results and Discussion

The surface morphologies of CaO-TiO2nanotubes synthe-

sized in 06Mcalciumnitrate solution for 24 48 and 72 hourswere subsequently observed via FESEM as presented in Fig-ures 1(a) to 1(c) respectively As shown in the FESEM imagesthe opening of the nanotubular structure showed aggregationof CaO species on wall surface of TiO

2nanotubes The

wall thickness of the nanotubes dramatically increased to

75 nm which resulted in a narrow pore entrance for 24 hoursreaction time (Figure 1(a)) Meanwhile as the reaction timeincreased to 48 hours the wall thickness of the nanotubesincreased from about 75 nm to 100 nm (Figure 1(b)) Withfurther increase of the reaction time to 72 hours it wasfound that the nanotubes were covered with excess CaOspecies and clogged the pore entrance (Figure 1(c)) A roughirregular and corrugated surface was formed Based on theFESEM images it could be concluded that the appearanceof TiO

2nanotubes was dependent on the reaction time in

calcium nitrate solution A narrow or blocked pore entranceof nanotubes was formed as increasing soaking period in thesolution Next the average atomic percentage (at) of theelements within CaO-TiO

2nanotubes was determined using

EDX analysis The numerical EDX analyses of the samplesare listed in Table 2 As determined through EDX analysisthe average Ca contents of the nanotubes for 24 48 and 72hours were 101 at 367 at and 459 at respectively Theintensity of the Ca peak (369 keV) increased with increasingreaction time in calcium nitrate solution as presented in


274

219

164

109

54

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

252

202

151

101

50

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

295

236

177

118

59

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)


Figures 2(a) to 2(c) Another set of experiments was con-ducted to form CaO-TiO

2nanotubes in 12M calcium nitrate

solution for 24 48 and 72 hours All morphologies of thesamples showed similar appearance of CaO-TiO

2nanotubes

synthesized in 06M calcium nitrate solution The irregularCaO layer covered all of the TiO

2nanotubular structure

and nanoporous structure arranged in a nonordered mannerwhich could be observed in Figures 3(a) to 3(c)The chemicalstoichiometry of the resultant samples was determined viaEDX analysis as shown in Figures 4(a) to 4(c) A high Cacontent of 978 atwas determined from those synthesized in12M calciumnitrate solution for 72 hours indicating that theincorporation of the CaO became prominent with increasingthe concentration of calcium nitrate solution Based on theFESEM images and EDX analysis the small Ca2+ ions couldbe diffused into TiO

2nanotubes in the presence of lattice

defects especially nearby to the wall of nanotubes In thiscase the diffusion rate of Ca2+ ions increased significantlywhen increasing the reaction time and concentration of pre-cursor However the content of small Ca2+ ions that diffusedinto the TiO

2lattice could reach a saturation condition and

start to accumulate on the surface of nanotubes The numberof nucleation sites for Ca2+ ions loaded on the wall surface ofthe nanotubes increasedwith longer reaction time and higherconcentration of precursor which produced nanotubes withthicker walls The diffusion of the Ca2+ ions formed CandashObonding withOndashTindashO bonding thus charge neutrality couldbe achieved

Table 2 EDX result of CaO-TiO2 with different soaking time in06M and 12M calcium nitrate solution

Concentration ofcalcium nitratesolution (M)

Element (at)reactiontime (h) Ti O Ca

0624 4607 5292 010148 3888 5745 036772 4230 5311 0459

1224 3644 6066 029048 3264 6064 066472 2883 6110 0978

In the present study XRD analysis was used to determinethe crystallographic structure and the changes in the phasestructure of the CaO-TiO

2nanotubes synthesized in different

reaction times and concentrations of precursor are presentedin Figures 5 and 6 Numerous studies reported that heattreatment at about 400∘C could transform the amorphousstructure of TiO

2into the crystalline anatase phase The

obvious diffraction peaks from the XRD pattern attributedto the anatase phase (JCPDS no 21-1272) were detected fromthe XRD patterns (Figure 5(a)) The diffraction peaks areallocated at 2532∘ 3784∘ 3842∘ 4802∘ 5387∘ 5509∘ 6293∘7065∘ and 7623∘ which correspond to 101 004 112 200105 211 204 220 and 301 crystal planes for the anatase


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)

Figure 5 XRD pattern of TiO2nanotubes incorporated with Ca in

06M Ca(NO3)2solution at different soaking period (a) pure TiO

2

(b) 24 hours (c) 48 hours and (d) 72 hours (A = anatase phase T =titanium phase)

10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2


phase respectively Apparently the incorporation of Ca2+ions into the lattice of TiO

2hindered the crystallization

of TiO2 resulting in the peak intensity of the 101 peak at

2532∘ decrease The decrease in anatase phase is maybe dueto the interruption of Ca atom which diffused into TiO

2

nanotubes and inhibited the formation of the anatase TheXRD pattern of the sample soaked in 12M for 72 hoursexhibits additional peaks 220 and 400 crystal planes at 54∘and 80∘ corresponding to CaO phase This indicates thatcrystalline CaO are formed once the concentration of Cain TiO

2reaches a higher level Next the resultant anodized

CaO-TiO2nanotubes were used in the characterization of

CO2adsorption using TGA analysis The processing steps

involved in TGA analysis are N2gas flow at a rate of 10∘Cmin

from room temperature to 673K and then holding for 30minin CO

2and finally cooling down to 573K byN

2gasThe TGA

curves for 06M of Ca and 12M of Ca are shown in Figures7 and 8 respectively while the CO

2adsorption capacity is

summarized in Table 3 Based on the TGA analysis it couldbe observed that all CaO-TiO

2samples showed their CO

2

adsorption capacity in the range of 33mmolg to 45mmolgA maximum CO

2adsorption capacity of up to 445mmolg

was observed from the CaO-TiO2nanotubes synthesized in

050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)

Figure 7 TGA curve of soaking in 06M of Ca for different periodsof time

050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature


Table 3 CO2 adsorption capacity of the CaO-TiO2 samples

Concentration of calciumnitrate solution (M)

Soaking period(hours)

CO2 adsorptioncapacity (mmolg)

0624 38948 33272 400

1224 35948 44572 380

12M of calcium nitrate solution for 48 hours Basically theCO2adsorption capacity based CaO-TiO

2sorbents used the

following reaction CaO + CO2rarr CaCO

3 In this case

the sorbent weight is increased significantly when CO2gas is

applied to the TGA system where all the weight added is CO2

adsorbed This reason clearly explains that CO2adsorption

capacity is increased after carbonation process


4 Conclusion

The present study demonstrated that one-dimensional CaO-TiO2nanotubes sorbent was successfully formed using oxi-

dation electrochemical anodization and wet impregnationtechniques All of the resultant CaO-TiO

2nanotubes sorbent

exhibited promising CO2adsorption capacity in the range of

33mmolg to 45mmolg It is shown that high active surfacearea of CaO-TiO

2nanotubes sorbent showed good stability

during extended cyclic carbonation-calcination reaction

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This research is supported by High Impact Research Chan-cellory Grant UMC6251HIR228 (J55001-73873) from theUniversity of Malaya In addition authors would like tothank University of Malaya for sponsoring this work underUniversity of Malaya Research Grant (UMRG no RP022-2012D)

References

[1] Q Wang J Luo Z Zhong and A Borgna ldquoCO2capture by

solid adsorbents and their applications current status and newtrendsrdquo Energy amp Environmental Science vol 4 no 1 pp 42ndash552011

[2] D M DrsquoAlessandro B Smit and J R Long ldquoCarbon dioxidecapture prospects for new materialsrdquo Angewandte ChemieInternational Edition vol 49 no 35 pp 6058ndash6082 2010

[3] SWang S Yan XMa and JGong ldquoRecent advances in captureof carbon dioxide using alkali-metal-based oxidesrdquo Energy ampEnvironmental Science vol 4 no 10 pp 3805ndash3819 2011

[4] N H Florin and A T Harris ldquoReactivity of CaO derived fromnano-sized CaCO

3particles through multiple CO

2capture-

and-release cyclesrdquo Chemical Engineering Science vol 64 no2 pp 187ndash191 2009

[5] J Garcıa T Lopez M Alvarez D H Aguilar and P QuintanaldquoSpectroscopic structural and textural properties of CaO andCaO-SiO

2materials synthesized by sol-gel with different acid

catalystsrdquo Journal of Non-Crystalline Solids vol 354 no 2-9 pp729ndash732 2008

[6] V R Choudhary S A R Mulla and B S Uphade ldquoOxidativecoupling of methane over alkaline earth oxides deposited oncommercial support precoated with rare earth oxidesrdquo Fuel vol78 no 4 pp 427ndash437 1999

[7] D Alvarez and J C Abanades ldquoPore-size and shape effects onthe recarbonation performance of calcium oxide submitted torepeated calcinationrecarbonation cyclesrdquo Energy and Fuelsvol 19 no 1 pp 270ndash278 2005

[8] J-R Li Y Ma M C McCarthy et al ldquoCarbon dioxidecapture-related gas adsorption and separation in metal-organicframeworksrdquo Coordination Chemistry Reviews vol 255 no 15-16 pp 1791ndash1823 2011

[9] S Sreekantan L C Wei and Z Lockman ldquoExtremely fastgrowth rate of TiO

2nanotube arrays in electrochemical bath

containing H2O2rdquo Journal of the Electrochemical Society vol

158 no 12 pp C397ndashC402 2011[10] CW Lai and S Sreekantan ldquoDimensional control of TiO

2nan-

otube arrays with H2O2content for high photoelectrochemical

water splitting performancerdquoMicro ampNano Letters vol 7 no 5pp 443ndash447 2012

[11] Y K Lai J Y Huang H F Zhang et al ldquoNitrogen-doped TiO2

nanotube array films with enhanced photocatalytic activityunder various light sourcesrdquo Journal of Hazardous Materialsvol 184 no 1ndash3 pp 855ndash863 2010

[12] S-H Liu C-H Wu H-K Lee and S-B Liu ldquoHighly stableamine-modified mesoporous silica materials for efficient CO

2

capturerdquo Topics in Catalysis vol 53 no 3-4 pp 210ndash217 2010[13] V Zelenak M Badanicova D Halamova et al ldquoAmine-

modified ordered mesoporous silica effect of pore size oncarbon dioxide capturerdquoChemical Engineering Journal vol 144no 2 pp 336ndash342 2008

[14] A R Millward and O M Yaghi ldquoMetal-organic frameworkswith exceptionally high capacity for storage of carbon dioxideat room temperaturerdquo Journal of the American Chemical Societyvol 127 no 51 pp 17998ndash17999 2005

[15] H Deng H Yi X Tang P Ning andQ Yu ldquoAdsorption of CO2

and N2on coal-based activated carbonrdquo Advanced Materials

Research vol 204-210 pp 1250ndash1253 2011[16] Q Li J Yang D Feng et al ldquoFacile synthesis of porous

carbon nitride spheres with hierarchical three-dimensionalmesostructures for CO

2capturerdquo Nano Research vol 3 no 9

pp 632ndash642 2010[17] Y Xia R Mokaya G S Walker and Y Zhu ldquoSuperior CO

2

adsorption capacity on N-doped high-surface-area microp-orous carbons templated from zeoliterdquo Advanced Energy Mate-rials vol 1 pp 678ndash683 2011

[18] Z Zhang M Xu H Wang and Z Li ldquoEnhancement of CO2

adsorption on high surface area activated carbon modified byN2 H2and ammoniardquo Chemical Engineering Journal vol 160

no 2 pp 571ndash577 2010[19] T C Drage J M Blackman C Pevida and C E Snape

ldquoEvaluation of activated carbon adsorbents for CO2capture in

gasificationrdquo Energy and Fuels vol 23 no 5 pp 2790ndash27962009

[20] Y Wang Y Zhou C Liu and L Zhou ldquoComparative studiesof CO

2and CH

2sorption on activated carbon in presence of

waterrdquoColloids and Surfaces A Physicochemical and EngineeringAspects vol 322 no 1ndash3 pp 14ndash18 2008

[21] F Su C Lu and H-S Chen ldquoAdsorption desorption andthermodynamic studies of CO

2with high-amine-loaded mul-

tiwalled carbon nanotubesrdquo Langmuir vol 27 no 13 pp 8090ndash8098 2011

[22] S U Rege and R T Yang ldquoA novel FTIR method for studyingmixed gas adsorption at low concentrations H

2O and CO

2on

NaX zeolite and 120574-aluminardquo Chemical Engineering Science vol56 no 12 pp 3781ndash3796 2001

[23] F Su C Lu S-C Kuo and W Zeng ldquoAdsorption of CO2on

amine-functionalized y-type zeolitesrdquo Energy and Fuels vol 24no 2 pp 1441ndash1448 2010

[24] A Ertan and F Cakicioglu-Ozkan ldquoCO2and N

2adsorption

on the acid (HCl HNO3 H2SO4and H

3PO4) treated zeolitesrdquo

Adsorption vol 11 no 1 pp 151ndash156 2005[25] F Brandani and D M Ruthven ldquoThe effect of water on the

adsorption of CO2and C

3H8on type X zeolitesrdquo Industrial amp

Engineering Chemistry Research vol 43 no 26 pp 8339ndash83442004


[26] L Li X Wen X Fu et al ldquoMgOAl2O3sorbent for CO

2

capturerdquo Energy and Fuels vol 24 no 10 pp 5773ndash5780 2010[27] M K RamReddy Z P Xu GQ Lu and J C DDaCosta ldquoLay-

ered double hydroxides for CO2capture structure evolution

and regenerationrdquo Industrial amp Engineering Chemistry Researchvol 45 no 22 pp 7504ndash7509 2006

[28] M Kato S Yoshikawa and K Nakagawa ldquoCarbon dioxideabsorption by lithium orthosilicate in a wide range of temper-ature and carbon dioxide concentrationsrdquo Journal of MaterialsScience Letters vol 21 no 6 pp 485ndash487 2002

[29] J-I Ida and Y S Lin ldquoMechanism of high-temperature CO2

sorption on lithium zirconaterdquo Environmental Science andTechnology vol 37 no 9 pp 1999ndash2004 2003

[30] E Ochoa-Fernandez H K Rusten H A Jakobsen MRoslashnning A Holmen and D Chen ldquoSorption enhanced hydro-gen production by steam methane reforming using Li

2ZrO3

as sorbent sorption kinetics and reactor simulationrdquo CatalysisToday vol 106 no 1-4 pp 41ndash46 2005

[31] E Ochoa-Fernandez M Roslashnning T Grande and D ChenldquoSynthesis and CO

2capture properties of nanocrystalline

lithium zirconaterdquo Chemistry of Materials vol 18 no 25 pp6037ndash6046 2006

[32] J A Satrio B H Shanks and T D Wheelock ldquoDevelopmentof a novel combined catalyst and sorbent for hydrocarbonreformingrdquo Industrial amp Engineering Chemistry Research vol44 no 11 pp 3901ndash3911 2005

[33] Z-S Li N-S Cai and Y-Y Huang ldquoEffect of preparationtemperature on cyclic CO

2capture and multiple carbonation-

calcination cycles for a new Ca-based CO2sorbentrdquo Industrial

amp Engineering Chemistry Research vol 45 no 6 pp 1911ndash19172006

[34] E P Reddy and P G Smirniotis ldquoHigh-temperature sorbentsfor CO

2made of alkali metals doped on CaO supportsrdquo The

Journal of Physical Chemistry B vol 108 no 23 pp 7794ndash78002004

[35] K Kuramoto S Fujimoto A Morita et al ldquoRepetitivecarbonation-calcination reactions of Ca-based sorbents forefficient CO

2sorption at elevated temperatures and pressuresrdquo

Industrial amp Engineering Chemistry Research vol 42 no 5 pp975ndash981 2003

[36] S F Wu T H Beum J I Yang and J N Kim ldquoProperties ofCa-base CO

2sorbent using Ca(OH)

2as precursorrdquo Industrial amp


[37] S F Wu Q H Li J N Kim and K B Yi ldquoProperties of a nanoCaOAl

2O3CO2sorbentrdquo Industrial amp Engineering Chemistry

Research vol 47 no 1 pp 180ndash184 2008

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Table 1 The different types of solid CO2 adsorbents based on their sorptiondesorption temperatures


Temperature(K)


Low temperature adsorbentsAmine based

Amine-modified mesoporous silica 45 348 1 (Liu et al 2010) [12]Amine-modified ordered mesoporous silica (OMS) 15 mdash mdash (Zelenak et al 2008) [13]Amine-modified OMSs 02ndash14 348 1 (Liu et al 2010) [12]Amine tetraethylenepentamine (TEPA)OMSs 46 348 1 (Liu et al 2010) [12]

MOFsZIFsMOF-2 32 mdash 41 (Millward and Yaghi 2005) [14]

Carbonactivated carbon basedCoal-based activated carbon 03 323 0001 (Deng et al 2011) [15]Porous carbon nitride (CN) 290 298 mdash (Li et al 2010) [16]N-doped carbons template from zeolite 69 273 1 (Xia et al 2011) [17]Activated carbonN2 375

293 1 (Zhang et al 2010) [18]Activated carbonH2 349Activated carbonNH3 322Activated carbon 15 303 40 (Drage et al 2009) [19]Activated carbon 35 275 1 (Wang et al 2008) [20]Carbon nanotubes (CNTs)3-aminopropyltriethoxysilane(APTS) 245 323 mdash (Su et al 2011) [21]

Alumina based120574-Al2O3 031 295 mdash (Rege and Yang 2001) [22]

Zeolite basedY-type zeolitetetraethyl-enepentamine (TEPA) 427 303ndash333 (Su et al 2010) [23]Natural zeolite 205

298 01 (Ertan and Cakicioglu-Ozkan2005) [24]

Treated zeoliteH3PO4 195Synthetic zeolite-5X 549Synthetic zeolite-13A 682LilSX 017

mdash 1 (Brandani and Ruthven 2004) [25]NaLX 023CaX 02413X (NaX) 294 295 mdash (Rege and Yang 2001) [22]

Magnesium basedMgOAl2O3 136 333 1 (Li et al 2010) [26]

Intermediate temperature adsorbentsLDH

Mg-Al-CO3 LDHs 049 473 005 (Ram Reddy et al 2006) [27]High temperature adsorbents

Lithium orthosilicatesLi4SiO4 614 773 1 (Kato et al 2002) [28]

Lithium zirconatesLi2ZrO3 455 773 1 (Ida and Lin 2003) [29]

Li2ZrO3 450 823 1 (Ochoa-Fernandez et al 2005)[30]

Li2ZrO3 (nanocrystalline) 614 848 1 (Ochoa-Fernandez et al 2006)[31]


Table 1 Continued


Temperature(K)





200nm

(a)

200nm

(b)

200nm

(c)












214

171

128

85

42

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

247

198

148

99

49

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

117

94

70

47

23

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)




2into





2










30 H2O2and 70 H



2nanotube arrays








2nanotubes


2nanotubes sorbents


2nanotubes sorbents


200nm

(a)

200nm

(b)

200nm

(c)













2nanotubes The








274

219

164

109

54

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

252

202

151

101

50

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

295

236

177

118

59

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)





2nanotubes











0624 4607 5292 010148 3888 5745 036772 4230 5311 0459

1224 3644 6066 029048 3264 6064 066472 2883 6110 0978







10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)



2


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2






2








2gasThe TGA





2




050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)


050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature






0624 38948 33272 400

1224 35948 44572 380


2sorbents used the


3 In this case






4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Table 1 Continued


Temperature(K)





200nm

(a)

200nm

(b)

200nm

(c)












214

171

128

85

42

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

247

198

148

99

49

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

117

94

70

47

23

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)




2into





2










30 H2O2and 70 H



2nanotube arrays








2nanotubes


2nanotubes sorbents


2nanotubes sorbents


200nm

(a)

200nm

(b)

200nm

(c)













2nanotubes The








274

219

164

109

54

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

252

202

151

101

50

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

295

236

177

118

59

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)





2nanotubes











0624 4607 5292 010148 3888 5745 036772 4230 5311 0459

1224 3644 6066 029048 3264 6064 066472 2883 6110 0978







10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)



2


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2






2








2gasThe TGA





2




050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)


050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature






0624 38948 33272 400

1224 35948 44572 380


2sorbents used the


3 In this case






4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


214

171

128

85

42

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

247

198

148

99

49

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

117

94

70

47

23

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)




2into





2










30 H2O2and 70 H



2nanotube arrays








2nanotubes


2nanotubes sorbents


2nanotubes sorbents


200nm

(a)

200nm

(b)

200nm

(c)













2nanotubes The








274

219

164

109

54

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

252

202

151

101

50

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

295

236

177

118

59

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)





2nanotubes











0624 4607 5292 010148 3888 5745 036772 4230 5311 0459

1224 3644 6066 029048 3264 6064 066472 2883 6110 0978







10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)



2


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2






2








2gasThe TGA





2




050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)


050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature






0624 38948 33272 400

1224 35948 44572 380


2sorbents used the


3 In this case






4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


200nm

(a)

200nm

(b)

200nm

(c)













2nanotubes The








274

219

164

109

54

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

252

202

151

101

50

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

295

236

177

118

59

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)





2nanotubes











0624 4607 5292 010148 3888 5745 036772 4230 5311 0459

1224 3644 6066 029048 3264 6064 066472 2883 6110 0978







10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)



2


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2






2








2gasThe TGA





2




050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)


050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature






0624 38948 33272 400

1224 35948 44572 380


2sorbents used the


3 In this case






4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


274

219

164

109

54

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(a)

252

202

151

101

50

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(b)

295

236

177

118

59

0

100 200 300 400 500 600 700 800 900 100

Ti

Ti

Ca

O

(c)





2nanotubes











0624 4607 5292 010148 3888 5745 036772 4230 5311 0459

1224 3644 6066 029048 3264 6064 066472 2883 6110 0978







10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)



2


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2






2








2gasThe TGA





2




050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)


050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature






0624 38948 33272 400

1224 35948 44572 380


2sorbents used the


3 In this case






4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

(d)

(c)

(b)

(a)TA T

T A AT

A T

T

T

2120579 (deg)



2


10 20 30 40 50 60 70 80 90

Inte

nsity

(au

)

AT A

TT

AT

TA

TT (a)

(b)

(c)

(d)

2120579 (deg)



2






2








2gasThe TGA





2




050100150200250300350400450

996998100

1002100410061008

101101210141016

0 20 40 60 80

Wei

ght (

)

Time (min)

24 hours48 hours

72 hoursTemperature

Tem

pera

ture

(∘C)


050100150200250300350400450

995

100

1005

101

1015

102

1025

0 20 40 60 80

Wei

ght (

)

Time (min)

Tem

pera

ture

(∘C)

24 hours48 hours

72 hoursTemperature






0624 38948 33272 400

1224 35948 44572 380


2sorbents used the


3 In this case






4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


4 Conclusion



2nanotubes sorbent







Acknowledgments


References







2capture-












2nan-






2










2








2and CH







2O and CO

2on





2adsorption









2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



2








2ZrO3
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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Research Article Modification of One-Dimensional TiO ...downloads.hindawi.com/journals/ijp/2014/471713.pdf · Research Article Modification of One-Dimensional TiO 2 Nanotubes with