surface modification of fly ash for active catalysis

Hindawi Publishing CorporationJournal of CatalystsVolume 2013 Article ID 723957 9 pageshttpdxdoiorg1011552013723957

Research ArticleSurface Modification of Fly Ash for Active Catalysis

Deepti Jain1 Renu Hada2 and Ashu Rani2

1 Department of Applied Chemistry Gautam Buddha University Greater Noida Uttar Pradesh 201308 India2Department of Pure and Applied Chemistry University of Kota Rajasthan 324005 India

Correspondence should be addressed to Deepti Jain deepti skjainyahoocom

Received 29 January 2013 Revised 5 May 2013 Accepted 20 May 2013

Academic Editor Vijay Bokade

Copyright copy 2013 Deepti Jain et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Fly ash based effective solid base catalyst (KFAl2O3fly ash473 KFAl

2O3fly ash673 and KFAl

2O3fly ash873) was synthesized

by loading KF over chemically and thermally activated fly ash The chemical activation was done by treating fly ash withaluminum nitrate via precipitation method followed by thermal activation at 650∘C to increase the alumina content in fly ashThe increased alumina content was confirmed by SEM-EDX analysis The alumina enriched fly ash was then loaded with KF (10wt) and calcined at three different temperatures 473K 673K and 873K The amount of loaded KF was monitored by XRDFTIR spectroscopy SEM-EDX TEM and Flame Atomic Absorption Spectrophotometer The catalytic activities of the catalystswere tested in the Claisen-Schmidt condensation of benzaldehyde and 4-methoxybenzaldehyde with 21015840-hydroxyacetophenoneto produce 21015840-hydroxychalcone and 4-methoxy-21015840-hydroxychalcone respectively Higher conversion (83) of benzaldehyde and(89) of 4-methoxybenzaldehyde reveals that among these heterogeneous catalysts KFAl

2O3fly ash673 is very active

1 Introduction

Fluoride ion is useful as weakly basic nonnucleophilicin many organic chemical processes involving hydrogenabstraction or hydrogen bond formation [1] Fluoride hasbeen reported as effective basic catalyst in Cannizzaro reac-tion to replace classical methods employing hydroxide basewhich gave large amount of Cannizzaro side reactions [2]Potassium fluoride is a well-known source of fluoride andpossesses a number of advantages of both solution and solidphase chemistry Among the supported fluoride systemspotassium fluoride on activated alumina has been foundto be more reactive than nonsupported KF KF-silica gelKF-celite and KF-molecular sieves [3] When KF is loadedon alumina it shows high catalytic activity towards organicreactions namely Michael addition [4] aldol condensa-tion [5] and transesterification reactions [6] The basic siteson KFalumina may be related to a very hard anion Fminusthe catalyst may show the characteristic performances whichdifferentiate KFalumina from the oxide-type solid basecatalysts such as alkaline earth oxides [7] In contrast tomany applications of KFalumina to organic synthesis as abase catalyst mechanisms of the appearance of the basicity

of KFalumina are not clarified Insufficient coordination ofKF only with surface OH groups may result in the formationof active Fminus ions [8] This possibility was supported by 19FMAS NMR [9] Three basic species or mechanisms of theappearance of the basicity of KFalumina reported previously[10] are (a) the presence of active fluoride (b) the presenceof [AlndashOndash] ion which generates OHminus when water is addedand (c) the cooperation of Fminus and [AlndashOH] It has beenreported in the literature (1) that the formation of potassiumhexafluoroaluminate must be accompanied by the formationof hydroxide andor aluminate responsible for the highreactivity of KFAl

2O3 However Fminus ion has little or no direct

role in the catalytic activity of KFAl2O3catalyst

12KF + Al2O3+ 3H2O 997888rarr 2K

3AlF6+ 6KOH (1)

The strong basic nature of KFAl2O3allowed it to replace

organic bases in a number of organic reactionsThe Claisen-Schmidt condensation between acetophe-

none and benzaldehyde derivatives is a valuable CndashC bond-forming reaction which produces 120572120573-unsaturated ketones

2 Journal of Catalysts

called chalcones which display a wide spectrum of biolog-ical activities including antioxidant antibacterial antileish-manial anticancer antiangiogenic anti-infective and anti-inflammatory activities [11ndash13] Traditionally the Claisen-Schmidt condensation is carried out using alkaline hydrox-ides or sodium ethoxide [14] The use of basic solids such aszeolites [15] alkali metal and oxides supported on alkalineearth oxide [16]MgO [17] calcined hydrotalcites [18] and KF[19] has received much attention over the last years as poten-tial catalysts for Claisen-Schmidt condensations Using solidcatalysts instead of stoichiometric amounts of soluble strongbases the overall atom efficiency of reactions is improvedprocesses are simplified the turn overnumber of the catalystis increased the volume of waste is significantly reduced andproduct workup becomes easier if necessary at all Typicallyorganic bases immobilized on different supports have beenused as catalytic materials Progress has predominately beenlimited because of leaching of the active material from thevarious types of support used

Fly ash (SiO2 Al2O3 Fe2O3 CaO and MgO) by appro-

priate activation has been converted into solid acids and solidbases H

2SO4treated fly ash has been used as Bronsted acid

catalyst for synthesis of aspirin and oil of wintergreen assolid support for loading of cerium triflate and sulphatedzirconia [20ndash22] for synthesis of 34-dimethoxyacetophenone(antineoplastic) and diphenylmethane In recent yearsfly ash treated with CaO NaOH MgO and aminopropyltrimethoxysilane has also been used as solid base catalysts invarious condensation reactions [23ndash26] In the present workwe attempted to introduce a novel solid base catalyst fromchemically activated fly ash by loading KF followed by ther-mal activation at different temperatures As received fly ash(silica 58) was chemically activated to increase alumina andwas thought to be used for supporting potassium fluorideThe use of fly ash as support not only reduced the cost ofthe catalyst it also showed high basicity and catalytic activ-ity for benzaldehyde and 4-methoxybenzaldehyde with 21015840-hydroxyacetophenone to produce 21015840-hydroxychalcone and 4-methoxy-21015840-hydroxychalcone in a single step liquid phaseand solvent free reaction conditions with high yield (gt90)and purity We also examined the changes in bulk andsurface structures of KFAl

2O3-fly ash catalysts pretreated at

different temperatures by XRD FTIR SEM-EDX and TEMto elucidate catalytically active sites formed by chemical andthermal treatment of fly ash

2 Experimental

21 Material Fly ash (Class F type with SiO2and Al

2O3gt

70) used as solid support for the solid base was collectedfrom Kota Thermal Power Plant (Rajasthan India) 120572-Alumina potassium fluoride (KF) aluminium nitrate(Al(NO

3)3sdot9H2O) (NH

4)2CO3 NH

4OH benzaldehyde

(99) 4-methoxybenzaldehyde (98) and 21015840-hydroxyaceto-phenone (99) were purchased from S D Fine Chem LtdIndia

22 Catalyst Preparation The three catalysts KFflyash KFAl

2O3fly ash and KFAl

2O3

were prepared by

using aqueous solution of potassium fluoride for wetimpregnation of fly ash alumina enriched fly ash and120572-alumina respectively All three catalysts were calcinedat different temperatures (473K 673K and 873K) andprepared by the following method

221 KFFly Ash Catalyst As received fly ash was preheatedfor 3 h at 900∘C under static conditions 10 g of thermallyactivated fly ash was added into a glass reactor containingaqueous solution of 0166 g potassium fluoride (10 wt)Thereactor was equipped with a reflux condenser and a magneticstirrer bar The slurry was refluxed at 110∘C for 24 h thenfiltered and washed to eliminate excess KF on the fly ashsurface

222 KFAl2O3Fly Ash Catalyst

Step 1 An aqueous solution of 009mol of Al(NO3)3sdot3H2O

was added into thermally activated fly ash with constant stir-ring Solution of 016mol of (NH

4)2CO3was added dropwise

in the above solution and the pH was maintained close to80 by the addition of appropriate amounts of NH

4OH (35

aqueous ammonia solution) The resulting gel-like slurrywas washed with deionized water until pH = 7 Then theprecipitate was dried at 373K in air for approximately 12 hThe resulting solid was calcined at 673K for 4 h under staticconditions

Step 2 The chemically activated fly ash was heated at 400∘Cfor 4 h prior to its introduction in a glass reactor containingaqueous solution of 0166 g potassium fluoride (10 wt) Thereactor was equipped with a reflux condenser and a magneticstirrer bar The slurry was refluxed at 110∘C for 24 h thenfiltered and washed to eliminate any excess KF on the fly ashsurface

223 KFAl2O3Catalyst 10 g of alumina milled to a fine

powder was added into deionized water containing desiredamount of KF (0166 g for 10wt loading) Thereafter theresulting solid products of all three catalysts were furtherdried at 110∘C for 24 h and calcined at three different temper-atures 473K 673K and 873K for 2 h

23 Characterization The samples were characterized byFourier transform infrared spectroscopy (FTIR) powder X-ray diffraction study (XRD) BET surface area analysis scan-ning electron microscopy (SEM) and transmission electronmicroscopy (TEM)The loading of KF on the chemically acti-vated fly ash was confirmed by FTIR study using FTIR spec-trophotometer (IRPrestige-21 Shimadzu) having a DiffuseReflectance Scanning technique by mixing the sample withdried KBr (in 120wt ratio) in the range of 400ndash4000 cmminus1with a resolution of 4 cmminus1 X-ray diffraction studies werecarried out by using X-ray diffractometer (Philips Xrsquopert)with monochromatic CuK

120572radiation (120582 = 154056 A) in a 2120579

range of 5 to 65∘ The detailed imaging information about themorphology and surface texture of the sample was providedby SEM-EDX (Philips XL30 ESEM TMP) The loading of KF

Journal of Catalysts 3

on fly ash particles was confirmed by TEM analysis (Tecnai20 G2 (FEI make) Resolution Line-14 A Point 204 A)

24 Reaction Procedure Claisen-Schmidt CondensationCatalytic activity of prepared catalysts was tested byClaisen-Schmidt condensation of benzaldehyde and 4-methoxybenzaldehyde with 21015840-hydroxyacetophenone insolvent free liquid phase reaction shown in Scheme 1

The condensation was performed in liquid phase batchreactor which consists of 50mL round bottom flaskmagnetic stirrer and condenser A mixture of benzalde-hyde (0106 g 1mmol) or 4-methoxybenzaldehyde (0136 g1mmol) and hydroxyacetophenone (0136 g 1mmol) wastaken in round bottom flask The catalysts activated atdifferent temperatures for 2 h (substrate to catalyst ratio =10) were added in the reaction mixture At the end of thereaction the catalyst was filtered and the reaction mixturewas analyzed by Gas Chromatography (Dani Master GC)having a flame ionization detector andHP-5 capillary columnof 30m length and 025mm diameter programmed oventemperature of 50ndash280∘C and N

2(15mLmin) as a carrier

gas

25 Catalyst Regeneration The used catalyst (KFAl2O3fly

ash673) was washed with acetone and dried in oven at 110∘Cfor 12 h followed by activation at 450∘C for 2 h before reusein next reaction cycle under similar reaction conditions asearlier

3 Results and Discussion

31 Characterization Elemental analysis of fly ash and allthree catalysts (KFfly ash KFAl

2O3fly ash and KFAl

2O3)

was done by EDX the results are summarized in Table 1Withincreasing the pretreatment temperature the contents of Kand F increased to a small extent by pretreatment at 673Kand decreased by pretreatment at 873K for all three samples

The FTIR spectrum of fly ash Figure 1 shows a peak at3600 cmminus1 which indicates the presence of surface minusOHgroups minusSi-OH and absorbed water molecules on the sur-face The spectra also shows a broad range of bands from1055 cmminus1 to 1100 cmminus1 which is attributed to modes of Si-O-Si asymmetric band stretching vibrations The low frequencymodes at 794 cmminus1 are due to the symmetric Si-O-Si stretch-ing vibrations The FTIR spectrum of KFAl

2O3fly ash

catalyst calcined at different temperatures (43K 673K and873K) shown in Figures 1(d) 1(e) and 1(f) The FTIR spec-trum of KFAl

2O3fly ash673 catalyst shown in Figure 1(e)

has a strong band at about 3500 cmminus1which indicates thepresence of ndashOH groups on the surface of KFAl

2O3fly

ash673 catalyst Thus result shows that hydroxyl groups canbe the active sites when KF is supported on fly ash [27]The intensity of the minusOH peak increases with increasingtemperature from 473K to 673K assigned due to increasein KF content Upon investigating the nature of the catalystvia infrared spectroscopic studies of the catalyst surface itbecame apparent that fluoride ion has little or no direct role

in the enhanced reactivity of KFAl2O3fly ash catalyst The

reaction between aqueous KF and alumina results in theformation of potassium hexafluoroaluminate and a stronglybasic surface consisting of potassium aluminates and potas-sium hydroxide [28] The later agents are responsible forboth the increased base activity and the variable activity aconsequence of carbonate formation A peak is present at1650 cmminus1 in the spectra of the samples which is attributed tobendingmode (120575

119874minus119867) of water molecule [5] An intense band

at 570 cmminus1 is also observed which is due to the presence ofsubstantial amount of hexafluoroaluminate ion In additionto features due to alumina and water bands at 1519 cmminus1 and1381 cmminus1 indicate that both bidentate and monodentate typecarbonate species exist on the surface of KFAl2O3fly ash673catalyst [5 29] which seems to be generated due to reactionof atmospheric CO2 with KOH during drying of the catalyst

X-ray diffraction pattern of raw fly ash is shown inFigure 2(a) Structural changes caused by pretreatment atdifferent temperatures were studied by XRD for KFAl

2O3fly

ash473 KFAl2O3fly ash673 andKFAl

2O3fly ash873 catalysts

illustrated in Figures 2(b) 2(c) and 2(d) These patternsconfirmed that deposition of the alkaline fluoride followedby the thermal treatment led to the formation of K

3AlF6by

the reaction between KF and Al2O3which is observed at

2 theta = 33∘ 38∘ and 63∘ The intensity of the peaks assignedto this species is in agreementwith the loadings of the alkalinefluoride [30]

SEM micrograph of raw fly ash Figure 3(a) shows thepresence of hollow cenospheres irregularly shaped unburnedcarbon particles mineral aggregates and agglomerated parti-cles while the typical SEM images of the fly ash supportedKF catalyst in Figure 3(b) show dense particles with dis-tribution of varying particle size TEM images of raw flyash Figure 4(a) show smooth spherical particles while TEMimage of KFAl

2O3fly ash673 catalyst Figure 4(b) shows KF

loaded spheres

32 Basic Sites on KFAl2O3Fly Ash Catalyst There are

several controversies on possibilities of formation of basicsites on KFAl

2O3catalytic system yet all the previous inves-

tigations [27] evidently reported the formation of K3AlF6by

the reaction of aqueous KF and alumina (1) Most of thestudies were of the opinion that Fminus ion has no direct role inthe catalytic activity of KFAl

2O3The formation of carbonate

on the catalyst surface is responsible for high reactivity ofKFAl

2O3[28] The carbonate was supposed to be formed by

the reaction of CO2and producedKOH (2) during the drying

procedure

4KOH + 2CO2997888rarr 2K

2CO3+ 2H2O (2)

Duke et al has reported the formation of K2CO3by the

following successive reactions

12KF + Al2O3997888rarr 2K

3AlF6+ K2O (3)

3K2O + 3CO

2997888rarr 3K

2CO3 (4)

where K2O is formed as the alumina lattice is destroyed

However in preparation of the KFAl2O3fly ash catalyst in


O O

O

OH OH

CH3

+

2-hydroxyacetophenone Benzaldehyde 2998400-hydroxychalcone

KFAl2O3fly ash

(a)

(b)

OCH3

OCH3

O

O

OHOH O

CH3

2-hydroxyacetophenone 4-methoxybenzaldehyde

+KFAl2O3fly ash

4-methoxy-2998400-hydroxychalcone

Scheme 1 Claisen-Schmidt condensation of (a) benzaldehyde and (b) 4-methoxybenzaldehyde with 2-hydroxyacetophenone over fly ashsupported solid base catalysts

Table 1 EDX analysis of prepared catalysts at different pre-treatment temperatures

Catalyst Pre-treatmenttemperature (K) K (at) F (at) Al (at) O (at)

Fly ash NIL 009 NIL 410 502

Al2O3fly ash 673K 009 NIL 92 576

KFfly ash473K 23 17 47 567673K 27 18 48 569873K 22 13 48 568

KFAl2O3fly ash473K 85 113 92 524673K 91 121 94 519873K 81 117 93 520

KFAl2O3

473K 208 196 127 469673K 221 208 129 442873K 188 177 172 463

[at atomic percentage]

aqueous medium (2) seems to be more significant than (3)and (4)

In KFAl2O3fly ash catalyst the formation of K

3AlF6is

confirmed by XRD while hydroxyl groups and carbonate ionare confirmed by intense peaks at 3500 cmminus1and 1550 cmminus1in FTIR spectrum Figure 1 Interestingly the pretreatmenttemperature has significantly affected the catalytic activityof the system as reported previously for KFAl

2O3catalyst

Both K3AlF6and carbonate peaks are observed on increasing

the pretreatment temperature from 473K to 873K as evidentfrom Figure 1 whereas the catalytic activity of KFAl

2O3fly

ash catalyst was almost diminished at higher temperature873K Figure 5(a) These results have ruled out the possibilityof carbonate or K

3AlF6being responsible for generating the

active basic sites on the catalyst surface KOH an active baseproduced during reaction between KF and alumina generateshydroxyl groups on the catalyst surface which becomeactive basic sites for condensation reactions At 873K sur-face hydroxyl groups are significantly decreased resulting

in decrease of active basic sites thus catalytic activity ofKFAl

2O3fly ash catalyst was almost completely lost Similar

explanations on the surface properties of KFAl2O3system

have been given in the literature [5] where the catalyticactivity of KF Al

2O3was completely lost

33 Catalytic Performance The catalytic activity ofKFAl

2O3fly ash depends very much on drying condition

of alumina after loading KF by impregnation In thisworkwe examined the dependence of catalytic activity forcondensation on the heating temperature of the catalyst

331 Effect of Pretreatment Temperature The catalyticactivity strongly depends on the evacuation temperatureand reached around a maximum temperature of 673KFigure 5(a) All catalysts showed significant activity forcondensation reactions whereas pure fly ash and chemicallyactivated fly ash (Al

2O3fly ash) did not show any activity

Among remaining catalysts the KFAl2O3fly ash673 showed


Tran

smitt

ance

()

4000 3000 2000 1000

Wave number (cmminus1)

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Figure 1 FTIR of (a) raw fly ash (b) thermally activated fly ash (c)KFfly ash catalyst (d)KFAl

2O3fly ash873 catalyst (e)KFAl

2O3fly

ash673 vatalyst (f) KFAl2O3fly ash473 catalyst and (g) regenerated

KFAl2O3fly ash673 catalyst

20 40 60 80 1000

200400

2120579

Inte

nsity

(a)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(b)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(c)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(d)

Figure 2 X-ray diffraction pattern of (a) raw fly ash (b)KFAl

2O3fly ash473 catalyst (c) KFAl

2O3fly ash873 and (d)


(a)

(b)

Figure 3 SEM micrograph of (a) Raw fly ash and (b) KFAl2O3fly

ash673 catalyst

higher catalytic activity giving maximum conversionof benzaldehyde (83) and 4-methoxybenzaldehyde(89) For KFAl


2O3fly ash873

conversions of benzaldehyde and 4-methoxybenzaldehydeare comparatively low as shown in Figure 5(a) The activityof KFAl

2O3fly ash catalyst appeared when the sample

was pretreated at 473K and reached its maximum at thetemperature of 673K As the pretreatment temperature wasraised higher than 673K the activity decreased sharplyand finally disappeared at the temperature of 873K It iswell reported that a high temperature treatment revealsactive sites on catalyst either by removal of CO

2and H

2O

remaining on the surface in various forms or by formationof specific surface structure The active sites are covered withH2O andor CO2 when pretreated below 673K [7]

In the light of the above inferences the reaction con-ditions such as reaction temperature reaction time molarratio of reactants and substrate to catalyst ratio for con-densation of benzaldehyde and 4-methoxybenzaldehydewith 21015840-hydroxyacetophenone were optimized using onlyKFAl

2O3fly ash673 catalyst

332 Effect of Temperature The reaction for condensation ofbenzaldehyde and 4-methoxybenzaldehyde is carried out attemperatures ranging from 40∘C to 140∘C for 4 h The effectof temperature on the condensation activity of KFAl

2O3fly

ash673 and kinetics is shown in Figure 5(b) It can be seen thatat 80∘C the conversion of benzaldehyde is 68 and increasesto 83 at 120∘C for a reaction time of 4 h which remainsconstant till 140∘C Similarly conversion of 4-methoxy ben-zaldehyde is maximum 89 at 140∘C


(a) (b)

Figure 4 TEM image of (a) Raw fly ash and (b) KFAl2O3fly ash673 catalyst

333 Effect of Reaction Time The optimum reaction timerequired achieving maximum conversion of benzalde-hyde and 4-methoxybenzaldehyde is carried out at 40 and140∘C for different time intervals from 30min to 8 h Theconversion of benzaldehyde and 4-methoxybenzaldehydegradually increases with time giving 83 and 89 after4 h respectively as given in Figure 5(c) which remains con-stant till 8 h

334 Effect of Molar Ratio (Substrate21015840-hydroxyaceto-phenone) The effect of the molar ratio of benzaldehydeto 21015840-hydroxyacetophenone and 4-methoxybenzaldehydeto 21015840-hydroxyacetophenone on conversion and yield ofproducts is also studied at a reaction temperature of120∘C and 140∘C and reaction time 4 h At the molar ratioof 1 1 maximum conversion of benzaldehyde and 4-methoxybenzaldehyde with yield of their respective productswas obtained (Figure 5(e)) With increasing the molar ratiothe conversion was observed to be decreased which can beattributed to formation of benzoic acid as side product

34 Comparison of Catalytic Activity of KFAl2O3Fly

Ash with the Literature Data The reaction between 21015840-hydroxyacetophenone and benzaldehyde has been carriedout over different catalysts as reported in the literatureThe results obtained from the reported catalysts showedthat when zeolite NaX and a sepiolite partially exchangedwith Cs were used as catalysts their activity was very low[31] It is because of the fact that H atoms present in themethyl group of acetophenone has high pKa value (158) andit has been demonstrated previously that the basic sitesof exchanged CsNaX and Cs sepiolite catalysts can onlyabstract proton with pKa = 107 and 133 respectively [31]So it is evident from the above results that a catalyst withstrong basic sites should be used to get the high conversionvalue It is also reported when an excess of Cs is exchangedwith zeolite it can give completely high conversion but thecatalyst have to be use in the inert atmosphere in order toavoid the formation of carbonates [32] Mg-Al hydrotalcitederived catalyst has also been used in this reaction and aconversion of 78 was obtained [33] The presence of wateralso affects the conversion value Similarly reaction between

4-methoxybenzaldehyde and 21015840-hydroxyacetophenone inthe presence of MeOHKOH at room temperature gives 65yield of 4-methoxy-21015840-hydroxychalcone in 24 h [34]

In order to find the optimum for the studied reactionswe have synthesized highly basic KFAl

2O3fly ash catalyst

and it is found that with this catalyst the conversion value(83) of benzaldehyde and (89) of 4-methoxybenzaldehydewas increased The prepared catalyst is also reused for upto three reaction cycles The regenerated catalyst showedsimilar catalytic activity till 3rd reaction cycle giving approx-imately similar conversion of benzaldehyde (81) and 4-methoxybenzaldehyde (86) which indicates that the sitesare not deactivated in the regenerated catalyst as confirmedby FTIR of regenerated catalyst (Figure 1(g))

35 Characterization of Products NMR of 21015840-hydroxy-chalcone H1-NMR (200MHz CDCl3) 120575 ppm 1278 (s1H 21015840-OH) 791minus796 (d 1H 119869 = 76Hz and 18HzH61015840) 791minus796 (dd 1H 119869 = 144Hz H

120573) 735minus770 (m 7H

H120572 H41015840 H2 H3 H4 H5 andH6) and 702minus709 (m 2H H31015840

andH51015840)NMRof 4-methoxy-21015840-hydroxychalconeH1-NMR(200MHz CDCl

3) 120575 ppm 1295 (s 1H 21015840-OH) 788minus796 (d

1H 119869 = 152 Hz H120573) 787minus791 (d 1H 119869 = 74Hz H61015840)

759minus766 (d 1H 119869 = 152Hz H120572) 762minus766 (d 2H 119869 = 88

Hz H2 and H6) 745minus749 (t 1H 119869 = 88 Hz and 76 HzH41015840) 690minus705 (m 4H H3 H5 H31015840 and 51015840 h) and 387 (s 3HOCH3)

4 Conclusion

The study provides KFAl2O3fly ash as an efficient solid

base catalyst possessing significant amount of basicity Thechemical activation of fly ash by alumina results in increasedamorphous alumina content and thus surface hydroxyl con-tents produced due to the reaction of KF and alumina on flyash support Among all catalysts KFAl

2O3fly ash catalyst

shows high catalytic activity towards condensation reactionThe experimental results indicate that the basicity of sup-ported KF can be significantly increased by a proper choiceof support In KFAl

2O3fly ash catalysts KF reacts with

alumina of fly ash and forms potassium hexafluoroaluminate


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()

Benzaldehyde4-Methoxybenzaldehyde

(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200

Temperature (∘C)Benzaldehyde4-Methoxybenzaldehyde

(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3

Conversion ()Yield ()

Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()

Conversion of benzaldehydeConversion of 4-methoxybenzaldehyde

(e)

Figure 5 Conversion () of benzaldehyde and 4-methoxybenzaldehyde with KFAl2O3fly ash catalyst at (a) different pretreatment

temperature (b) different reaction temperature (c) different time (d) different reaction cycles and (e) different molar ratios of benzaldehydeand 4-methoxybenzaldehyde


and hydroxide as the major phase which increases withincrease in calcination temperature from 473K to 673Kresponsible for enhancement of reactivity of catalyst Alongwith these species bidentate carbonate species exist on thesurface of KFAl

2O3fly ash673 catalyst which is formed by

the formation of K2CO3 The KFAl

2O3fly ash catalysts

were found active for condensation of benzaldehyde and4-methoxybenzaldehyde with 21015840-hydroxyacetophenone inwhich KFAl

2O3fly ash pretreated at 673K gave higher

conversion of benzaldehyde (87) with 91 yield of 21015840-hydroxychalcone and 4-methoxybenzaldehyde (93) with93 yield of 4-methoxy-21015840-hydroxychalcone Experimentalresults also indicate that the basicity generated over onlyKFfly ash catalyst was not sufficient to get higher yieldof condensation products but when fly ash was chemicallyactivated by loading alumina through precipitation usingaluminium nitrate as precursor KFAl

2O3fly ash catalyst

has shown increased catalytic activity for the same reactionThe conversion (83 and 89) of benzaldehyde and 4-methoxybenzaldehyde in KFAl

2O3fly ash catalytic system

was comparable to the only KFAl2O3system (conversion

61 and 59) however the cost of the KFAl2O3fly ash

is lower than the KFAl2O3 due to the replacement of 120572-

alumina support by aluminafly ash support Fly ash alreadyhas 17 wt alumina and by chemically activating it withaluminium nitrate the alumina content was increased upto 37wt which is found to be responsible for generatingsufficient basic sites to catalyze the Claisen-Schmidt conden-sationThis catalyst may further be explored for several otherorganic transformations

Recycling experiments showed that the catalyst is verystable up to three cycles A composite material which cancombine the advantages of fly ash alumina and KF canexpand the catalytic capabilities of the material especially inapplications as strong base catalysts for industrially importantreactions

Conflict of Interests

The prepared KFAl2O3fly ash catalyst is novel and cost

effective The cost of the KFAl2O3fly ash is lower than the

commercially available KFAl2O3 due to the replacement 120572-

alumina support by aluminafly ash support Fly ash alreadyhas 17 wt alumina and by chemically activating it withaluminium nitrate (cheaper than pure alumina) the aluminacontent was increased up to 37wt which is found to beresponsible for generating sufficient basic sites to catalyze theClaisen-Schmidt condensation So the prepared catalyst mayfurther be used for several other organic transformations incost effective wayWe have used the 120572-alumina for comparingthe catalytic activity of the prepared catalyst There is nodirect relationship with the commercial identity Chem Ltd

Acknowledgments

XRD and TGA support was provided by Dharmsinh DesaiUniversity Nadiad Gujarat and TEM was performed atUGC-DAE Consortium for Scientific Research Indore Fly

ash Mission Department of Science and Technology NewDelhi India provided the financial support through researchProject no FAUDST600(23)2009-10 sanctioned to thecorresponding author

References

[1] N Ohtani Y Inoue A Nomoto and S Ohta ldquoPolystyrene-supported ammonium fluoride as a catalyst for several base-catalyzed reactionsrdquo Reactive Polymers vol 24 no 1 pp 73ndash781994

[2] L M Weinstock J M Stevenson S A Tomellin et alldquoCharacterization of the actual catalytic agent in potassiumfluoride on activated alumina systemsrdquo Tetrahedron Letters vol27 no 33 pp 3845ndash3848 1986

[3] C V A Duke J M Miller J H Clark and A P Kybett ldquoAcomparison of the adsorption of KF and NH4F onto silica gelrdquoSpectrochimica Acta A vol 46 no 9 pp 1381ndash1389 1990

[4] H Kabashima H Tsuji T Shibuya and H Hattori ldquoMichaeladdition of nitromethane to 120572120573-unsaturated carbonyl com-pounds over solid base catalystsrdquo Journal of Molecular CatalysisA vol 155 no 1-2 pp 23ndash29 2000

[5] H Handa T Baba H Sugisawa and Y Ono ldquoHighly efficientself-condensation of benzaldehyde to benzyl benzoate over KF-loaded aluminardquo Journal of Molecular Catalysis A vol 134 no1ndash3 pp 171ndash177 1998

[6] M Verziu M Florea S Simon et al ldquoTransesterification ofvegetable oils on basic large mesoporous alumina supportedalkaline fluorides-Evidences of the nature of the active site andcatalytic performancesrdquo Journal of Catalysis vol 263 no 1 pp56ndash66 2009

[7] K Tanabe M Misono Y Ono and H Hattori New Solid Acidsand Base Kodansha-Elsevier Tokyo Japan 1989

[8] H Hattori ldquoSolid base catalysts generation of basic sites andapplication to organic synthesisrdquo Applied Catalysis A vol 222no 1-2 pp 247ndash259 2001

[9] T Baba A Kato H Takahashi et al ldquoMetathesis of silylalkynesand cross-metathesis of silylalkyne and 1-alkyne over solid-basecatalystsrdquo Journal of Catalysis vol 176 no 2 pp 488ndash494 1998

[10] H Kabashima H Tsuji S Nakata Y Tanaka and H HattorildquoActivity for base-catalyzed reactions and characterizationofalumina-supported KF catalystsrdquo Applied Catalysis A vol 194-195 pp 227ndash240 2000

[11] S J Won C T Liu L T Tsao et al ldquoSynthetic chalconesas potential anti-inflammatory and cancer chemopreventiveagentsrdquo European Journal of Medicinal Chemistry vol 40 no1 pp 103ndash112 2005

[12] S Alam and S Mostahar ldquoStudies of antimicrobial activityof two synthetic 210158404101584061015840-trioxygenated flavonesrdquo Journal ofApplied Sciences vol 5 no 2 pp 327ndash333 2005

[13] J B Daskiewicz F Depeint L Viornery et al ldquoEffects offlavonoids on cell proliferation and caspase activation in ahuman colonic cell line HT29 an SAR studyrdquo Journal ofMedicinal Chemistry vol 48 no 8 pp 2790ndash2804 2005

[14] S Abello D V Shankar and J P Ramırez ldquoStability reuti-lization and scalability of activated hydrotalcites in aldolcondensationrdquoApplied Catalysis A vol 342 no 1-2 pp 119ndash1252008

[15] A Dhakshinamoorthy M Alvaro and H Garcia ldquoClaisen-schmidt condensation catalyzed bymetal-organic frameworksrdquo


Advanced Synthesis and Catalysis vol 352 no 4 pp 711ndash7172010

[16] A Corma and S Iborra ldquoOptimization of alkaline earth metaloxide and hydroxide catalysts for base-catalyzed reactionsrdquoAdvances in Catalysis vol 49 pp 239ndash302 2006

[17] B M Choudary K V S Ranganath J Yadav and M LakshmiKantam ldquoSynthesis of flavanones using nanocrystalline MgOrdquoTetrahedron Letters vol 46 no 8 pp 1369ndash1371 2005

[18] M J Climent A Corma S Iborra K Epping and A VeltyldquoIncreasing the basicity and catalytic activity of hydrotalcites bydifferent synthesis proceduresrdquo Journal of Catalysis vol 225 no2 pp 316ndash326 2004

[19] D J Macquarrie R Nazih and S Sebti ldquoKfnatural phosphateas an efficient catalyst for synthesis of 21015840-hydroxychalcones andflavanonesrdquo Green Chemistry vol 4 no 1 pp 56ndash59 2002

[20] C Khatri D Jain and A Rani ldquoFly ash-supported ceriumtriflate as an active recyclable solid acid catalyst for Friedel-Crafts acylation reactionrdquo Fuel vol 89 no 12 pp 3853ndash38592010

[21] C Khatri M K Mishra and A Rani ldquoSynthesis and char-acterization of fly ash supported sulfated zirconia catalyst forbenzylation reactionsrdquo Fuel Processing Technology vol 91 no10 pp 1288ndash1295 2010

[22] CKhatri andA Rani ldquoSynthesis of a nano-crystalline solid acidcatalyst from fly ash and its catalytic performancerdquo Fuel vol 87no 13-14 pp 2886ndash2892 2008


[24] D Jain C Khatri and A Rani ldquoSynthesis and characterizationof novel solid base catalyst from fly ashrdquo Fuel vol 90 no 6 pp2083ndash2088 2011

[25] D Jain C Khatri and A Rani ldquoMgO enriched coal fly ash ashighly active heterogeneous base catalyst for Claisen-Schmidtcondensation reactionrdquo Journal of the American Chemical Soci-ety vol 1 no 2 pp 37ndash49 2011

[26] D JainMMishra andA Rani ldquoSynthesis and characterizationof novel aminopropylated fly ash catalyst and its beneficialapplication in base catalyzed Knoevenagel condensation reac-tionrdquo Fuel Processing Technology vol 95 pp 119ndash126 2012

[27] JMClacensDGenuit LDelmotte et al ldquoEffect of the supporton the basic and catalytic properties of KFrdquo Journal of Catalysisvol 221 no 2 pp 483ndash490 2004


[29] CV ADuke and JMMiuer ldquo19FmasNMRand FTIR analysisof the adsorption of alkali metal fluorides onto aluminardquoJournal of Molecular Catalysis vol 62 no 2 pp 233ndash242 1990


[31] A Corma V Fornes R M Martin-Aranda H Garcia and JPrimo ldquoZeolites as base catalysts condensation of aldehydeswith derivatives of malonic estersrdquoApplied Catalysis vol 59 no1 pp 237ndash248 1990

[32] M Larpess A Camboda D Bronel J Rodriguesz and P Gen-este ldquoCharacterization of basicity in alkaline cesium-exchangedX zeolites post-synthetically modified by impregnation a TPDstudy using carbon dioxide as a probe moleculerdquo MicroporousMaterials vol 1 no 5 pp 343ndash351 1993

[33] M J Climent A Corma S Iborra and J Primo ldquoBase catalysisfor fine chemicals production claisen-schmidt condensation onzeolites and hydrotalcites for the production of chalcones andflavanones of pharmaceutical interestrdquo Journal of Catalysis vol151 no 1 pp 60ndash66 1995

[34] T D Tran H Park G F Ecker and K M Thai ldquo21015840-hydroxychalcone analogues synthesis and structure-PGE2inhibitory activity relationshiprdquo in Proceedings of the 12th Inter-national Electronic Conference on Synthetic Organic Chemistry(ECSOC rsquo08) November 2008

Submit your manuscripts athttpwwwhindawicom

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2013


Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom


Analytical ChemistryVolume 2013

ISRN Chromatography


Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawi Publishing Corporation httpwwwhindawicom Volume 2013

The Scientific World Journal


Bioinorganic Chemistry and Applications


Journal of

SPECTROSCOPY

ISRN Analytical Chemistry


ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013


Advances in

Physical Chemistry

ISRN Physical Chemistry


SpectroscopyInternational Journal of


ISRN Inorganic Chemistry



Journal of

Chemistry


Inorganic Chemistry International Journal of


International Journal ofPhotoenergy


Analytical Methods in Chemistry

Journal of

Volume 2013

ISRN Organic Chemistry



CatalystsJournal of


called chalcones which display a wide spectrum of biolog-ical activities including antioxidant antibacterial antileish-manial anticancer antiangiogenic anti-infective and anti-inflammatory activities [11ndash13] Traditionally the Claisen-Schmidt condensation is carried out using alkaline hydrox-ides or sodium ethoxide [14] The use of basic solids such aszeolites [15] alkali metal and oxides supported on alkalineearth oxide [16]MgO [17] calcined hydrotalcites [18] and KF[19] has received much attention over the last years as poten-tial catalysts for Claisen-Schmidt condensations Using solidcatalysts instead of stoichiometric amounts of soluble strongbases the overall atom efficiency of reactions is improvedprocesses are simplified the turn overnumber of the catalystis increased the volume of waste is significantly reduced andproduct workup becomes easier if necessary at all Typicallyorganic bases immobilized on different supports have beenused as catalytic materials Progress has predominately beenlimited because of leaching of the active material from thevarious types of support used

Fly ash (SiO2 Al2O3 Fe2O3 CaO and MgO) by appro-

priate activation has been converted into solid acids and solidbases H

2SO4treated fly ash has been used as Bronsted acid

catalyst for synthesis of aspirin and oil of wintergreen assolid support for loading of cerium triflate and sulphatedzirconia [20ndash22] for synthesis of 34-dimethoxyacetophenone(antineoplastic) and diphenylmethane In recent yearsfly ash treated with CaO NaOH MgO and aminopropyltrimethoxysilane has also been used as solid base catalysts invarious condensation reactions [23ndash26] In the present workwe attempted to introduce a novel solid base catalyst fromchemically activated fly ash by loading KF followed by ther-mal activation at different temperatures As received fly ash(silica 58) was chemically activated to increase alumina andwas thought to be used for supporting potassium fluorideThe use of fly ash as support not only reduced the cost ofthe catalyst it also showed high basicity and catalytic activ-ity for benzaldehyde and 4-methoxybenzaldehyde with 21015840-hydroxyacetophenone to produce 21015840-hydroxychalcone and 4-methoxy-21015840-hydroxychalcone in a single step liquid phaseand solvent free reaction conditions with high yield (gt90)and purity We also examined the changes in bulk andsurface structures of KFAl

2O3-fly ash catalysts pretreated at

different temperatures by XRD FTIR SEM-EDX and TEMto elucidate catalytically active sites formed by chemical andthermal treatment of fly ash

2 Experimental

21 Material Fly ash (Class F type with SiO2and Al

2O3gt

70) used as solid support for the solid base was collectedfrom Kota Thermal Power Plant (Rajasthan India) 120572-Alumina potassium fluoride (KF) aluminium nitrate(Al(NO

3)3sdot9H2O) (NH

4)2CO3 NH

4OH benzaldehyde

(99) 4-methoxybenzaldehyde (98) and 21015840-hydroxyaceto-phenone (99) were purchased from S D Fine Chem LtdIndia

22 Catalyst Preparation The three catalysts KFflyash KFAl

2O3fly ash and KFAl

2O3

were prepared by

using aqueous solution of potassium fluoride for wetimpregnation of fly ash alumina enriched fly ash and120572-alumina respectively All three catalysts were calcinedat different temperatures (473K 673K and 873K) andprepared by the following method

221 KFFly Ash Catalyst As received fly ash was preheatedfor 3 h at 900∘C under static conditions 10 g of thermallyactivated fly ash was added into a glass reactor containingaqueous solution of 0166 g potassium fluoride (10 wt)Thereactor was equipped with a reflux condenser and a magneticstirrer bar The slurry was refluxed at 110∘C for 24 h thenfiltered and washed to eliminate excess KF on the fly ashsurface

222 KFAl2O3Fly Ash Catalyst

Step 1 An aqueous solution of 009mol of Al(NO3)3sdot3H2O

was added into thermally activated fly ash with constant stir-ring Solution of 016mol of (NH

4)2CO3was added dropwise

in the above solution and the pH was maintained close to80 by the addition of appropriate amounts of NH

4OH (35

aqueous ammonia solution) The resulting gel-like slurrywas washed with deionized water until pH = 7 Then theprecipitate was dried at 373K in air for approximately 12 hThe resulting solid was calcined at 673K for 4 h under staticconditions

Step 2 The chemically activated fly ash was heated at 400∘Cfor 4 h prior to its introduction in a glass reactor containingaqueous solution of 0166 g potassium fluoride (10 wt) Thereactor was equipped with a reflux condenser and a magneticstirrer bar The slurry was refluxed at 110∘C for 24 h thenfiltered and washed to eliminate any excess KF on the fly ashsurface

223 KFAl2O3Catalyst 10 g of alumina milled to a fine

powder was added into deionized water containing desiredamount of KF (0166 g for 10wt loading) Thereafter theresulting solid products of all three catalysts were furtherdried at 110∘C for 24 h and calcined at three different temper-atures 473K 673K and 873K for 2 h

23 Characterization The samples were characterized byFourier transform infrared spectroscopy (FTIR) powder X-ray diffraction study (XRD) BET surface area analysis scan-ning electron microscopy (SEM) and transmission electronmicroscopy (TEM)The loading of KF on the chemically acti-vated fly ash was confirmed by FTIR study using FTIR spec-trophotometer (IRPrestige-21 Shimadzu) having a DiffuseReflectance Scanning technique by mixing the sample withdried KBr (in 120wt ratio) in the range of 400ndash4000 cmminus1with a resolution of 4 cmminus1 X-ray diffraction studies werecarried out by using X-ray diffractometer (Philips Xrsquopert)with monochromatic CuK

120572radiation (120582 = 154056 A) in a 2120579

range of 5 to 65∘ The detailed imaging information about themorphology and surface texture of the sample was providedby SEM-EDX (Philips XL30 ESEM TMP) The loading of KF






gas





2O3fly ash and KFAl

2O3)



2O3fly ash




2O3fly







2O3fly




3AlF6by





loaded spheres










procedure


2CO3+ 2H2O (2)




3AlF6+ K2O (3)

3K2O + 3CO

2997888rarr 3K

2CO3 (4)




O O

O

OH OH

CH3

+


KFAl2O3fly ash

(a)

(b)

OCH3

OCH3

O

O

OHOH O

CH3


+KFAl2O3fly ash







KFfly ash473K 23 17 47 567673K 27 18 48 569873K 22 13 48 568

KFAl2O3fly ash473K 85 113 92 524673K 91 121 94 519873K 81 117 93 520

KFAl2O3

473K 208 196 127 469673K 221 208 129 442873K 188 177 172 463




3AlF6is


2O3catalyst



2O3fly
















Tran

smitt

ance

()

4000 3000 2000 1000


(a)

(b)

(c)

(d)

(e)

(f)

(g)



2O3fly



20 40 60 80 1000

200400

2120579

Inte

nsity

(a)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(b)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(c)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(d)





(a)

(b)


ash673 catalyst



2O3fly ash873




2and H

2O





2O3fly



(a) (b)








2O3fly ash catalyst



120573) 735minus770 (m 7H



3) 120575 ppm 1295 (s 1H 21015840-OH) 788minus796 (d

1H 119869 = 152 Hz H120573) 787minus791 (d 1H 119869 = 74Hz H61015840)



4 Conclusion



2O3fly ash catalyst





0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()


(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200


(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3


Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()


(e)











2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of






gas





2O3fly ash and KFAl

2O3)



2O3fly ash




2O3fly







2O3fly




3AlF6by





loaded spheres










procedure


2CO3+ 2H2O (2)




3AlF6+ K2O (3)

3K2O + 3CO

2997888rarr 3K

2CO3 (4)




O O

O

OH OH

CH3

+


KFAl2O3fly ash

(a)

(b)

OCH3

OCH3

O

O

OHOH O

CH3


+KFAl2O3fly ash







KFfly ash473K 23 17 47 567673K 27 18 48 569873K 22 13 48 568

KFAl2O3fly ash473K 85 113 92 524673K 91 121 94 519873K 81 117 93 520

KFAl2O3

473K 208 196 127 469673K 221 208 129 442873K 188 177 172 463




3AlF6is


2O3catalyst



2O3fly
















Tran

smitt

ance

()

4000 3000 2000 1000


(a)

(b)

(c)

(d)

(e)

(f)

(g)



2O3fly



20 40 60 80 1000

200400

2120579

Inte

nsity

(a)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(b)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(c)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(d)





(a)

(b)


ash673 catalyst



2O3fly ash873




2and H

2O





2O3fly



(a) (b)








2O3fly ash catalyst



120573) 735minus770 (m 7H



3) 120575 ppm 1295 (s 1H 21015840-OH) 788minus796 (d

1H 119869 = 152 Hz H120573) 787minus791 (d 1H 119869 = 74Hz H61015840)



4 Conclusion



2O3fly ash catalyst





0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()


(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200


(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3


Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()


(e)











2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of


O O

O

OH OH

CH3

+


KFAl2O3fly ash

(a)

(b)

OCH3

OCH3

O

O

OHOH O

CH3


+KFAl2O3fly ash







KFfly ash473K 23 17 47 567673K 27 18 48 569873K 22 13 48 568

KFAl2O3fly ash473K 85 113 92 524673K 91 121 94 519873K 81 117 93 520

KFAl2O3

473K 208 196 127 469673K 221 208 129 442873K 188 177 172 463




3AlF6is


2O3catalyst



2O3fly
















Tran

smitt

ance

()

4000 3000 2000 1000


(a)

(b)

(c)

(d)

(e)

(f)

(g)



2O3fly



20 40 60 80 1000

200400

2120579

Inte

nsity

(a)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(b)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(c)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(d)





(a)

(b)


ash673 catalyst



2O3fly ash873




2and H

2O





2O3fly



(a) (b)








2O3fly ash catalyst



120573) 735minus770 (m 7H



3) 120575 ppm 1295 (s 1H 21015840-OH) 788minus796 (d

1H 119869 = 152 Hz H120573) 787minus791 (d 1H 119869 = 74Hz H61015840)



4 Conclusion



2O3fly ash catalyst





0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()


(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200


(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3


Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()


(e)











2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of


Tran

smitt

ance

()

4000 3000 2000 1000


(a)

(b)

(c)

(d)

(e)

(f)

(g)



2O3fly



20 40 60 80 1000

200400

2120579

Inte

nsity

(a)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(b)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(c)

600

20 40 60 80 1000

200400

2120579

Inte

nsity

(d)





(a)

(b)


ash673 catalyst



2O3fly ash873




2and H

2O





2O3fly



(a) (b)








2O3fly ash catalyst



120573) 735minus770 (m 7H



3) 120575 ppm 1295 (s 1H 21015840-OH) 788minus796 (d

1H 119869 = 152 Hz H120573) 787minus791 (d 1H 119869 = 74Hz H61015840)



4 Conclusion



2O3fly ash catalyst





0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()


(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200


(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3


Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()


(e)











2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of


(a) (b)








2O3fly ash catalyst



120573) 735minus770 (m 7H



3) 120575 ppm 1295 (s 1H 21015840-OH) 788minus796 (d

1H 119869 = 152 Hz H120573) 787minus791 (d 1H 119869 = 74Hz H61015840)



4 Conclusion



2O3fly ash catalyst





0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()


(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200


(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3


Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()


(e)











2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000Temperature (K)

Con

vers

ion

()


(a)

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

()

0 50 100 150 200


(b)

Time (h)0 5 10

0102030405060708090

100

Con

vers

ion

()


(c)

0102030405060708090

100

0 1 2 3


Con

vers

ion

()

Number of cycles

(d)

2 1 1 1 1 2

Con

vers

ion

() a

nd y

ield

()

Molar ratio

0

10

20

30

40

50

60

70

80

90

100

1 4

Yield ()Yield ()


(e)











2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of









2O3fly ash catalyst













Acknowledgments



References














































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of































ISRN Chromatography







Journal of

SPECTROSCOPY






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




CatalystsJournal of

surface modification of fly ash for active catalysis

Documents