Synthesis and performance evaluation of silica-supported copper chromite catalyst for glycerol dehydration to acetol

Article abstract of DOI:10.1007/s12039-019-1662-1

Abstract: Sol-gel technique was used to prepare silica-supported copper chromite catalyst from acid hydrolysis of sodium silicate. The catalyst was characterized by BET surface area, FESEM, XRD, H₂-TPR and pyridine adsorption by FTIR. The catalyst was activated in a hydrogen atmosphere based on H₂-TPR result. The surface acidity of the catalyst was evaluated by NH₃-TPD and pyridine adsorption. XRD result of reduced catalyst showed the presence of Cu⁰, Cu¹⁺ and Cr₂O₃ in the catalyst. Glycerol dehydration was carried out at different temperature (180?°C to 240?°C) from aqueous glycerol solution with the reduced catalyst in a batch reactor. The glycerol conversion was reached 100% with maximum acetol selectivity of 70% for highest Copper chromite loaded (40?wt%) on silica at 220?°C in atmospheric pressure. The distilled liquid product was analyzed by high-performance liquid chromatography. Oxidized catalyst and spent catalyst showed lower glycerol conversion with low acetol selectivity than the reduced form of the catalyst. This is due to the cuprous ion in the reduced form of the catalyst, which acts as Lewis acid sites in glycerol dehydration. Graphic abstract: Glycerol dehydration to acetol with reduced form of silica-supported copper chromite catalyst is reported. The reduced form of copper chromite (cuprous oxide) on silica surface acts as a lewis acid in glycerol dehydration. Cuprous oxide coordinates with terminal hydroxyl group of glycerol and forms low energy six-membered transition state in the dehydration reactions.[Figure not available: see fulltext.].

Full text of DOI:10.1007/s12039-019-1662-1

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
Ó In di an Aca dem y of Sc i en c es
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REGULAR ARTICLE
Synthesis and performance evaluation of silica-supported copper
chromite catalyst for glycerol dehydration to acetol
*
S BAS U, A K SE N
an d M MUKH ERJE E
De p ar t m en t of Ch e m ic al En gi nee ri ng, B ir la In s ti t ut e of Tech nol ogy Mes r a, R anchi , J har kha nd, In di a
E- ma i l: ak hi ls e n@ bi tm es r a. ac .in ; ak h il s e n@ yahoo .c o. i n
MS r ecei v ed 1 0 M ay 2 01 9 ; r ev i s ed 1 6 J un e 2 0 1 9; accep t ed 3 0 J u n e 2 0 1 9
Abstract. S o l- g el te c hn iq ue w as u s ed t o pr epare s i li ca- s upp ort ed cop per chr om i t e cat al ys t fr om a ci d
h y d ro lys i s of s od i um s il ic at e. Th e cat al ys t was cha r act eri ze d by B ET s ur face are a, F ES EM , XR D, H - TP R
2
a n d py r i di ne ad s or pt ion by F TI R . Th e cat al ys t was act i va t ed i n a hyd rog en at m os p her e bas e d on H - TP R
2
re s u l t. Th e s ur f ace ac i di ty of th e ca tal ys t was eva l uat ed by NH -TP D and pyr i di ne ads o rpt io n. XR D r es u l t o f
3
0
re d u ce d ca tal ys t s ho w ed th e pr es e nce o f C u , C u and C r O i n t he cat al ys t . Gl yce r ol deh ydr ati o n wa s
1 ?
2
3
c ar ri e d ou t at di f fe re nt te m per at ur e (1 80 °C t o 240 °C ) fr om aqu eou s gl yc ero l s ol ut i on wi t h t he r ed uc e d
c at a l ys t in a ba tc h r eac tor . Th e gl yc ero l con ver s i on was rea ched 100 % wi t h m ax i m um acet ol s el ec ti v i t y o f
7
0 % f or hi gh es t Co pp er ch ro m i te lo a d ed (4 0 wt % ) on s i li c a at 220 °C i n at m os p her ic pr es s ur e. Th e d is t i l le d
l i q u id pr o du c t w as an al yze d by hi gh- per for ma nc e l iq ui d chr om at ogr aphy . Ox i di zed cat al ys t and s p en t c at -
a ly s t s ho w ed lo w er gl yc er ol co nv er s i o n wi t h l ow acet ol s el ect i vi ty t han t he red uc ed fo rm of t he cat al y st . T h i s
i s d u e to th e cu pr ou s io n in th e r ed uced fo rm of t he cat al ys t , wh ich act s as Lew is aci d s i te s i n g ly c e ro l
d e hy d r at io n.
Keywords. G lyc er ol ; co pp er ch ro m i t e; acet ol ; pyr i din e-F TI R; H -TP R ; XR D.
2
1
. Introduction
gl yc er ol to ot he r va lu e- a dde d c om mod ity pr od uc ts a r e
m ai nly ba se d on pr oc e sse s li ke he te r oge ne ous c a ta ly-
si s of hy dr oge nol ysi s, de hyd ra t ion, e the r ific a ti on,
B i o d ie s e l h a s s h own po t en ti a ls t o ac t as t he sup ple -
m e nt o f fo s s il di e sel si n ce i t i s a r ene wab le a nd
e n v ir o n me n t -fr i en dl y so ur ce of en er gy . Bu t t he m aj or
o b s tr u c tio n to u s e bi o di es el i s t he hi g h co st of pr o-
d u c ti o n . Bi o d ie se l si g ni fic an t ly r edu ce s e ngi ne
e m is s io n s s u c h a s su l fu r di o xi de ( 10 0%) , u nbur n ed
h y dr o ca rb o n s (6 8 %) an d p ol yc yc li c ar om at ic hyd r o-
2
c ar bo n s (8 0 – 9 0 % ). To p ro du ce 9 kg of b iod ie se l,
3– 5
6
e tc .
Ma r io a nd P ag lia r o sum m ar i ze twe n ty- tw o
di ff e r en t pos sib le wa ys to c onve r t gl yc er ol in to va lue -
a dde d pr od uct s li ke pol yhy dr oxyl al ka noa te s, c itr i-
c ac id , hy dr oge n, 2’ 2- di me thy l-1’ 3- di oxol an - 4-m e thy-
la c et a te , m onog lyc e ri de , e tc .
1
Gly ce r ol de hyd ra t ion pr im a r ily r es ult s in two dif -
f er e nt pr od uct s. One is a cr ol e in, a nd th e o the r is
hyd r oxya c et one ( HA) or a ce to l whi ch c an be f ur the r
c onve r te d in to 1,2 a nd 1,3 -p ro pa ne dio l thr oug h
a b o u t 1 k g o f c ru de gl y ce ro l i s f or med as a b y- pr odu ct .
M o s t o f th e b io d i es el p ro du cer s r efin e g ly ce ro l f or sa le
a s a c o mm o d it y i n t he gl y ce ro l ma rk et . Se ve ra l st ep s
7
,8
hyd r oge na tio n. Ac et ol pl ay s a ve r y im por t an t r ole in
or ga ni c syn the si s a nd in te rm e dia t es . Als o, it is us e d in
(
a c id a n d a lk a l i tr ea tm en t f ol l owed by di s ti l l ati on) a re
u s e d to p u ri fy g ly ce ro l f ro m t he cr ud e so l uti on to
0 – 8 5 % g ly c e ro l . Fu rt h er pu r ifi cat i on t o pr o du ce pur e
9
in dust ri es li ke f ood , dy es a nd a ddi tiv es. The p r ic e of
8
a ce to l is hi gh a nd it is pr od uce d in dust ri al l y f r om
pe tr ol eu m r es our c es . C ru de pe tr ol eu m r es er ve s a r e
de pl et ing da y by da y a nd he nc e a bi o- ba se d so ur c e of
a ce to l is a n ob viou s c hoi ce of r es ea r c h. I n th e lit er a -
tu re , se ve r al tr a nsi tio n m et al c at al yst s ha ve be e n te s te d
f or gl yc er ol de hyd ra t ion. C oppe r is we ll kno wn f or the
lo wer a bil ity to c le av e th e C -C bon ds of a glyc e r ol
m ole c ule , r es ult ing in und es ir a ble de gr a da tio n pr od-
g l y ce ro l in c r e as e s t he ov er al l pr i ce , wh ic h i s n ot c ost -
e ffe c ti v e. Ho we v er , an i nc re as e i n t he pr o du ct ion of
b i o di e s e l is e x p e c te d t o r edu ce t he p ri ce o f g lyc e r ol,
a n d a ls o , th e g ly c er ol co nv er si o n t o o th er co nsu me r
p ro d u c ts is mu c h mo re de si r ab le . Th e sp ec tr um of
g l y ce ro l u ti li z a tio n ha s al s o g ro wn su ch t ha t pr e se ntl y
i t ha s o v e r 1 5 0 0 kn o wn en d u ses . Th e co nv er si on of
1
0
1 1
uc ts . Hua ng et al., ha ve pr e pa re d si lic a - suppor t ed
*
F o r co rr e sp on den ce

8
2
Pa g e 2 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
C u O c a ta ly s t b y g el p rec i pi ta t io n t ec hn iq ue du e to 2. Experimental
s t ro n g c o p p e r/s u p por t i nt er ac t io n, an d t hi s c at al yst
2
.1 Materials
p ro v e s to b e mu c h mo re ac t iv e. Th ey ha ve re por t ed
t h a t th e c o n v e rs io n of g ly ce ro l i s 7 3%. Th i s i s du e to
h i g h c o p p e r d is p e rs io n an d sm al l me ta l pa rt i cl e si ze .
Ki m et al., h a ve us ed ch ro mi um t o p ro mo te th e
a ct i v ity o f c o p p e r. Th ey ha ve d one co -p r eci p it a ti on of
c h ro mi u m wi th co pp er wh ic h dr am at ic al l y i nc r ea se s
t h e a c ti v ity o f g ly ce ro l, co nv er t s 87 % to 1,2 -
p ro p a n e d io l wi th 8 4% se l ect i vi t y. Be cau se of th e
Gl yce r ol (A R gr ade) was pur ch as ed fr om (N ic e c he mi c a l
P vt . Lt d. ) fo r deh ydra t i on s t ud i es . Ace to l (S i gm a- A l dr i c h)
was us ed as a ref eren ce fo r HP LC cal i brat i on. S od i um si l -
i cat e (N a S i O . 9H O, Lob a C he m i e), P ol yvi nyl a lc o ho l
1
2
2
3
2
(P VA , Mol . wt . 850 00–1 2 400 0, S . D. F i ne C hem . L td . )
wer e us ed fo r s i li ca s upp ort p rep arat i o ns . P hen ol ( A R
gr ade) was us ed t o i ncre as e t he por os i ty of t he s i li ca ma t r ix .
s y n e rg is ti c e ffe c t o f Cu an d Cr t he ac t iv i ty of c oppe r The act i ve com p ound cop per chr om i te (C uO . Cu Cr O ) wa s
c h ro mi te c a ta ly s t i s h ig he r t ha n an i nd iv i du al c at a- pur ch as ed fr om S p ect ro ch em In di a.
2
4
1
3 ,1 4
l y s t .
i t y b ut is e a s il y s in t er ed . I n t he ca t al ys t, ch ro miu m a ct s
Co p p e r i nc re as es t he i nt r in si c ca t al yst a ct iv-
1
5
a s a s ta b i lis e r to re du ce t he si n te ri n g r at e. Sa to et al.,
2.2 Catalyst preparation
h a v e s h o wn th a t ba si c su pp or t ( M gO, Ca O, ZnO)
e ffe c ti v el y s h o ws l ow ac et ol se l ect i vi t y b ut a ci dic
s u p p o rt (S iO , A l O , Zr O , F e O ) ef f ect i ve ly pr o-
Si li ca s upport ed copper chrom it e cat al ys t was prepare d f ro m
aci d hydrolysis of s odium s il icate (Na Si O ) b y s ol -g el
2
3
2
2
3
2
2
3
2 3
t echnique. P ol yvinyl alcohol (PVA) was added as a sta bi-
l izer t o get regul ar particle s izes . A s mall quant it y of p he no l
was added t o i ncreas e t he poros it y i n t he s ili ca mat ri x.
During hydrolysi s s toichi om et ri c amount of copper, chr omit e
was added t o incorporate i nt o the s il ica m at ri x. A t yp ic al
react ion s chem e was as foll ows. 2 gm of PVA was disso lv ed
m o t e s a c et o l s e le ct i ve ly . Co pp er ch ro mi te i s o ne of th e
e ffi c ie n t c a ta ly s t s f or co nv er t in g gl y ce ro l to a ce -
1
6 , 1 7
t o l .
s p e c ie s in th e c u b ic sp i na l f or m i s v ery i mpo r ta nt f or a
In a d d it io n, t he l ow ox i da ti on st a te o f c oppe r
1
8
c at a ly t ic a p p li c a ti o n. Vas i li ad ou an d Le mo nid ou
h a v e u s e d c o p p e r su pp or t ed on me so po ro us si li c a f or i n 100 m L of dis ti ll ed wat er and the requi red quant it y o f
g l y ce ro l h y d ro g e n ol y si s r eac t io n. Th ey o bse rv e d th at s odium s ili cate s ol ut ion was added to i t. The m ixtu re was
s t ro n g d e a c tiv a ti o n f or t hi s ca t al ys t i s d ue t o c oppe r heated t ill 60 °C , under agi tated condi ti on usi ng mag ne ti c
s ti rrer and 10 gm of phenol was added i nt o t he m ixtu re . 2 N
p a rti c le s in t e rin g an d st r on gl y ad so rb ed ca rb on a ce ou s
HCl s olution was added dropwis e i nt o t he m ixture in h ea ti ng
d e p o s it in th e me so po ro us st r uc tu re s. Dep en di ng on
and s ti rring condi ti on t o m ake the s ol ut ion aci di c. T he
t h e c a ta ly s t a n d th e o per at i ng co nd i ti on s, t he r ea c ti on
addit ion of aci d was conti nued up t o i ni tiati on of clo ud f or -
o f g ly c e ro l h y d ro gen ol y si s p ro cee ds t hr ou gh two
9
,1 9 , 2 0
m at ion. Then des ired amount of copper chromi te p owde r
(pass through 75 m icron m es h s ize) was added i nt o t he
m e ch a n i s ms .
I n o ne of t he me ch an is m , de hy-
d ra ti o n o f g ly c e ro l t o f or m ac et ol on ac i d si te s wa s
fo l l o we d b y h y d r og ena t io n st e p o n me ta l si de s.
An o t h e r me c h a n is m i s wh er e de hy dr og en a tion of
g ly c er ol t o gl yc er al d e hy de s o ve r b as i c s i te wa s f ol -
s ol ut ion. The pH of the mi xt ure was adjust ed t o 1–2 b y t he
addit ion of 2 N HCl s oluti on t il l t he end. The hea tin g a nd
s ti rring were conti nued for another 2 h. The reacti on mix tu re
was l eft for 24 h. Then t he preci pi tate was fi lte re d a nd
l o w e d b y d e h y d rat i on t o ac et ol an d fin al l y hyd r o- was hed wit h dis ti ll ed wat er s everal t imes unt il t he rem ov al o f
g e n a tio n to p ro p yl en e g ly co l. Si n ce hy d ro ge na tio n free aci d. The preci pi tate was dri ed in an air oven at 1 00 °C
re q u ire s h ig h h yd r og en pr es su re so si d e re a ct ion unti l const ant wei ght. Then it was grounded and cal ci ne d i n a
m uffle furnace at 500 °C for 4 h. The cat al ys t was act iv at ed
i n a t ubular furnace at 350 °C f o r 4 h i n a h y d r o g e n a tm o -
s phere. The yield of t he blank s il ica was 10 g for t he t yp ic al
com posi ti ons and t he l oading l evel was cal culated based o n
t he atomic wei ght % of copper as per m ol ecular f or mu la
o c c u rs to fo rm s e ve ra l by - pr od uc ts i nc lu di n g e thy le ne
g l y co l, la c t ic a c id , p ro pi on ic ac i d, et c .
9, 21 ,22
I n th i s s tu d y , a c et ol p ro du ct io n was o pt im ize d wit h
t h e h e lp o f s il ic a -su pp o rted co pp er ch ro mi te ca ta ly st.
Th e c a ta ly s t wa s sy nt h es iz ed f ro m ac i d h ydr ol ysis of
s o d iu m s il ic a te . T he ac t iv e co mp on en t co pp er c hr o-
m i te wa s a d d e d du r in g t he sy nt h es is of si l i ca . The
c at a ly s t wa s a c t iv at ed i n a hy d ro gen at m osph er e
b e fo re g ly c e ro l d eh yd ra t io n. Th e ca t al ys t wa s c ha r-
a ct e riz e d b y BE T su r fa ce ar ea , FE SEM , XRD, TGA,
H - TP R, NH -T PD, py r id in e FT IR. Th e r eac t i on wa s
(
(
CuO. CuCr O ) provi ded by the s uppl ier to m ai nt ai n t he
2 4
Cu:Si O ) mass rat io. The com posi ti on of t he diffe re nt c at-
2
alyst s ys tem and nom encl at ure were given i n Table 1.
2.3 Characterization of catalyst
2
3
c ar ri e d o u t wi th d if fe re nt ca t al yt ic sy st e m b y va r yin g Ni t roge n ads o rpt io n -d es orpt i o n i s ot her m s m eas ur ed a t 7 7 K
re a ct io n c o n d it io n s. Ba se d on t he r eac t io n pr od uct s a wi t h a m ul t ip o i nt m et hod us i n g Qu a nt ach rom e No va t ou c h
s ur face are a and a po re s i ze ana ly zer . The cat al ys t sa m p le s
wer e deg as s ed at 2 00 °C fo r 4 h und er vac uum .
m e c h a n is m h a v e be en p ro po sed f or g et ti n g hi gh
s e l e ct iv it y o f a c eto l .

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
Table 1. Co m po s it io ns an d no m en cl at ure of t he cat al ys t .
P age 3 of 15 82
C u : S i O 2
Mas s rat i o
Se ri a l N o.
S od iu m s il ic at e ( g)
C opper C hro m i te (g )
No me nc l at ure
1
2
3
4
5
47
–
0: 10
1: 9
2: 8
3: 7
4: 6
S i O 2
42 .6
37 .8
33 .1
28 .4
2. 4
4. 8
7. 4
9. 8
S i C uC r1 0
S i C uC r2 0
S i C uC r3 0
S i C uC r4 0
T h e i m ag e s o f su r fac e m or ph ol og y an d th e ele m ent al i n t he s ys t em . Ther m al t reat m e nt was per for me d a nd t he
m app i n g o f t h e c at al ys t w er e de te rm in ed by F iel d E mi s s i on t em per at ure ro s e fr om 50 °C t o 750 °C a t 1 0 °/ m in . In o rd er t o
S ca n n i n g El e c t ro n Mi cr os co py ( FE SEM ) us i ng S ig m a 300 det er m i ne t he aci di t y of t he cat al ys t fr om NH -TP D p ro fil e s‘
3
wi t h EDA X (A m et ek ) at di f f er ent m ag ni fi cat ion lev el. The are as und er t he cur ves wer e i nt egr at ed by Gau s s i an d e co n-
p o wd e r wa s g o l d -c oa te d be fo r e F ES EM s tu d ie s and el e- vol ut i on of t he pea ks and am ou nt of aci di t y was exp re s se d i n
m ent a l m ap p i n g .
X- ra y d i ffr ac t i on ( XR D) pa tt er ns of ca tal ys ts wer e
m i cro m ol es per gr am of t he cat al ys t .
To det er m in e t he nat ur e of aci d and s t reng th of a ci d si t e s
o b tai n e d a t ro o m te m per at ur e us i n g a Ri ga ku , J apa n pyr i din e ads o r bed F TIR was don e (S hi m ad zu Co r pn . ,
Di f f ra c t o m et e r (S m ar t Lab , 9 kW ) eq ui pp ed w ith a ver ti c al J apa n ; IR -P r es t i ge 21) . B efor e rec o rd in g ana l y si s, a ll
g o n i o m et e r. Th e sc an s w er e co ll ect e d in th e ran ge of red uced cat al ys t s am pl e s and pyr i di ne wer e t ak en i n a
2
h = 1 0 – 8 0
u s i n g
co pp er
( Cu K a1
r ad ia ti on , s epa rat e P e t ri di s h , and kep t i n a vac uum ove n (5 00 mm
k = 1 .5 4 0 5 6 n m , 4 5 K V an d 2 00 m A ) at th e s ca nn in g s pee d Hg ) ove rn i ght t o rea ch equ il i bri um . B efor e ana l y si s, t he
o f 0. 0 5 °(2 h)/ s . Th e di f fr ac t og r am s of th e ex pe r im en t wer e s am pl e s wer e t aken out fr om vac uum ove n and t he sp e c-
co mp a re d wi t h t h e I CD D po w der di f fr a ct io n fi le dat a bas e .
Th e t h er ma l s t a bi li ti es of th e ca t al ys ts w er e de t erm i ned
b y t h er m o g ra v im e t r ic an al ys is ( TG A ) us i ng a S HI MA DZU
t rum s wer e rec orde d i n DR S m ode .
t h er m o g ra v im e t ri c an al yze r D TG 60 m od e l. Th e cat al ys t 2.4 Catalytic performance evaluation
s amp l e wa s h e at e d in a pl at inu m pa n f ro m r oo m tem p era-
t u re t o 8 0 0 °C a t a h ea tin g r ate of 10 °C/ m in un de r ni t roge n Deh yd rat i on of gl ycer ol was car r i ed out i n a s t ai nles s st e e l
at mo s p h e re.
bat ch rea ct or of 500 m L cap aci ty (A m a r Equ ipm e n t , I nd i a)
Te m p e ra tu r e p ro gr am m ed r edu c ti on ( H - TP R) of s i li ca- equ ip p ed wi t h an el ect ri cal t em per at ure con tr ol l er a nd a
2
s u pp o r t ed c o pp e r ch ro m i te ca tal ys t w as pe rf o rm ed i n m ech ani cal s t ir rer . Th e rea ct ion was car ri e d out at v ar i ou s
Qu a n ta c h ro me C h em Be t P ul s u r ch em is o rp t io n fl o w ana - t em per at ure s at at m os p her ic p res s u re. 20% aqu eou s g ly c -
l y zer e q ui p p e d wi t h th er m al co nd uc ti vi ty de te ct or (TC D) . ero l s ol ut i on was fed i nt o t he rea ct or ves s e l and 1 g r ed uc e d
2
4
Th e re d u ct i o n e x pe r im e nt w as ca rr ie d ou t in a U- s hape d cat al ys t was add ed i nt o t he rea c t or. The gl yc e ro l a nd
q u ar tz re a ct o r . Ex ac tly 0. 1 g of po w der e d s am pl e was cat al ys t m i xt ure was agi t at ed at a s pee d of 700 r pm t o
p l ace d i n t h e re a ct o r . P ri or to th e r edu ct ion , th e ca ta ly s t was cre at e a s l urr y rea ct ion m i xt ure. The di s t il l ed pr od uc t wa s
p r e-t re a t e d t o 2 0 0 °C at th e he at ing r ate of 10 °C /m i n i n con den s ed by pas s i ng t he vap our t hro ugh a wat er co nd e n se r
h el iu m g a s flo w o f 80 m L/m i n. A ft er 30 m in at 200 °C t he i n wh ich chi l l ed wat er at 10 °C was ci rcu l at ed. I ni t i al
cat a l y s t wa s c o ol e d do w n to r oo m te m per at ur e in Hel i um fr act io n (f rom ro om t em per at ur e t o 100 °C ) of t he d is t i l le d
(
He) a tm o s p h e re. Fo r r edu c ti on , a r edu ci ng ga s ( 5% H i n pr oduc t was di s car d ed as i t i s con s ide red t hat t he d eh y-
2
Ar ) wa s u s ed a t t h e fl ow r at e of 80 m L/m i n. Th e tem p era- dr ati o n rea ct ion s t art s abo ve 100 °C . The di s t il l ed p ro d uc t
t u re wa s g ra d u al l y in cr ea s ed f ro m am b ie nt te m per at ur e t o was col l ect e d aft er rea chi n g t he des i re d t emp e r a tu r e
7
5 0 °C a t t h e h e at i ng r ate of 10 °C/ m in . H co ns um pt i on (1 80 °C , 200 °C , 220 °C , 240 °C ) and ana ly zed by HP LC
2
wa s m o n i t o re d b y th e th er m al co nd uc ti vi ty de te ct o r (TC D) (h ig h-pr es s ur e l iq ui d chr om at ogr aph y) . The rea cti o n wa s
co nt i n u o u s l y .
con ti nu e d up t o 3 h at t he rea c t io n t em per at ure . Th e d is -
To d e te rm i n e t h e nu m b er of ac id s it es of th e cat al ys t ‘ t il l ed pr oduc t s wer e col l ec t ed, s eal ed and s t ored for a na l y-
am mo n i a (N H ) t em p er at ur e- pr og r am m ed de s or pt io n (TP D ) s i s . The res i du e i n t he rea ct or was col l ec t ed and a ft e r
3
wa s p e rfo rm e d i n t he ab ov e in s tr u m en t. Be f or e ca rr yi ng out wei gh i ng i t was was h ed wi t h m et han ol fo ll owe d b y fil t r a-
t h e TP D e x pe r i m en t of th e ca tal ys t, ab ou t 0. 1 g of s am pl e was t io n and ai r dr yi ng t o s epa rat e t he s pen t cat al ys t .
p r e- tr e at e d i n He l iu m fl ow ( 80 m L/ m in ) at 20 0 °C a t hea ti ng
r at e 1 0 °/ m in fo r t h e 30 m in . A ft er co ol in g th e ca tal ys t i n a
2.5 HPLC analysis of distillates
h el i u m a tm o s p h e re t o 40 °C th e he li um am m o ni a ga s m i xt ure
(
5 % NH – 9 5 % He ) fl ow w as s ta r ted an d co nt in ued up t o
3
To qua nt if y t he pr oduc t s obt ai ned fr om t he ca t a ly t i c
deh ydr at i on of gl yc ero l hi gh- per for ma nc e l i qu i d
3 0 mi n . Th e n p u re h el iu m ga s fl o w w as s ta rt ed at ro om
t emp e r a tu r e fo r 3 0 m in to r em ov e an y am m o nia ga s pr es ent

8
2
Pa g e 4 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
2
5
11,2 7
18
V as ilia d u et al., h ave rep ort ed that th e
ch r o ma t o g ra p h y (H PL C) f ro m w ate rs w as us e d. The ma tr ix.
HP L C s y s t e m wa s eq ui pp ed w ith tw o pu m p s ( wa t ers 515
a ctiv ity of the highl y d ispe r sed c oppe r in a me sopor ous
s i l i ca-bas ed ca ta l ys t fo r t h e h yd rog eno l y si s o f gl yc er o l
r e duc e s due t o the st r on g a ds or pt io n of c a r bo nac eo u s
m a te r i a l i nsi de t he p or e st ruc t ur e .
HP L C p u m p ) a n d U V/ V is d et ect or ( w at er 24 87 dua l k
ab s or b a n ce d e te c to r ). A ce to ni tr il e an d w ate r m ix tu re wer e
u s ed a s t h e m o b i le ph as e at th e vo lu m e r ati o 40: 60 i n
i so cr at i c m o d e . Th e fl o w r ate of th e m ob il e pha s e was
fi x ed a t 0 .1 m L/ mi n. C- 1 8 co lu m n w as us e d i n t hi s
2
6
3.1 b Field emission scanning electron microscope
(
s tu d y. Th e i n j ec t io n vo lu m e w as 20 lL. Th e ter m s of
co nv e r s i o n a n d s el e ct ivi t y w er e de fi ned by th e f o ll owi ng
ex pr es s i o n .
FESEM): F ES EM m ic ro gr ap hs of th e c oppe r
c hr om ite sa m ple s a t 25 K m ag nifi c at ion a re s hown
in F igu re 1 . C at al yst s a re go ld- c oa te d f or F ES EM
st udie s. The im a ge s sho w th at th e pow der s c a ta lys ts
a re ir r e gul ar in sha pe a nd S iC uCr 4 0 c at a lys t is
di ff e r en t f r om ot he rs . Thi s m ay be due to th e high er
lo ad ing of c oppe r c hr om ite whe r e th e pr op orti on of
si lic a r ed uc es in th e si lic a m at ri x, whi ch r es ults in a
r ed uc tio n of th e pr ob abi lit y of c onde ns at ion be tw e en
si lic a po wder s.
G lyc e r ol co nv e r sio n %
I nit i al m as s of gl y ce ro l a nd c at a ly st À R e sid u e a ft er re act ion
¼
In i ti a l ma ss o f g ly c er o l
 1 00
ð1 Þ
Th e s el e ct i v i ty o f th e pr o du c ts ( ace to l, ac eta lde h yd e and
acet i c a ci d , e tc .) was ca l cu la ted ba s ed on th e f or mu la:
Ma s s of s pe cif ic pr o du c t
3.1 c EDX
(energy
dispersive
X-ray
P r od u c t s el e ct i v it y % ¼
 100
Ma s s of al l li qu id pr o du c ts
spectroscopy): Figure 2 i s t he elem en tal m apping of
Si Cu Cr 2 0, Si C uCr 30 a nd Si Cu Cr 4 0. Th i s s ho w s c o pp e r
and ch ro mi um at oms are e venl y di st r ib ut ed t hr ou gho ut
t he si l ic a m a t rix . Ta b l e 3 is t he E D X a nal ysi s of si l ic a-
supp or t ed c oppe r c hr omi t e ca t al yst . The a to m ic pe r cen t
o f co p per and ch romi um is in creas i n g o rd er a s t he
dopin g le ve l inc re a ses in the sil ica suppor t. ED X s tudy is
m a in l y t he s u rfa c e c o nc e n tra t i on o f at om s, whi c h a re
re s po ns ibl e fo r c a t a lyt i c p urpo se s . As ex pe c t e d 40 wt %
s amp le s sh o w th e h ig h es t co n te nt o f c op pe r a nd
c hr om ium. Al l t he s a m pl e s c ont a in sod iu m i on whi ch
is c om m on for pr e c ip it a t e d si l ic a sa m pl es. K i na ge
ð2 Þ
3
. Results and Discussion
Si l i c a -s u p p o rt e d c op pe r ch ro mi te ca t al ys t ar e p r epa r e d
b y a c id h y d ro ly s i s o f so di u m si l i cat e an d c oppe r
c h ro mi te is a d d e d d ur in g t he pr ep ar at i on o f si l ic a . The
p re c ip i ta te d ma t e ri a l i s was he d an d dr i ed i n a ir ove n
fo l l o we d b y c a lc in a ti on at 50 0 °C f or 4 h i n a m uf fle
fu r na c e . T h e p ro p er t ie s of t he sy nt h es iz ed ca t al yst a re
e v a lu a t e d b y BE T sp ec ifi c su r fa ce ar ea , F ES EM,
XR D, T GA, H -T PR, NH - TPD an d p yr id in e F TI R.
2
8
et al., ha s re por t ed t ha t 5 wt % of sod ium lo a de d in
me ta l oxi de gr eatly e nha nc es the ac etol selec tivi ty in
g ly cero l con vers i on .
2
3
3
3
. 1 Catalyst characterization results
3.1 d Powder X-ray diffraction (XRD): Fi gur e 3
sho ws th e XR D di ff r a ct ion of c al ci ne d s ilic a -
. 1 a BET surface area: T he su rf ac e a r ea a nd por e sup por te d c oppe r c hr om ite c at al yst . A br oa d a nd
volume of s ilic a- s upp ort ed cop p e r c h r o mite a r e g iv e n in di ff us e pe a k is ob ser ve d a t 20° in lo wer lo ad ing c oppe r
Ta b l e 2. T h e s u r fa ce a r ea a n d p o r e v o l u me a r e h i g h es t c hr om ite a s c om pa re d to hi ghe r on es. Thi s pe a k is
f o r 3 0 wt% co p pe r c hr o m ite co n tain in g s ilica f ollo w ed a ttr i bute d to S iO . Thi s is due to th e di ff r a ct ion of the
2
by S iC uCr 40. T he BJ H p o re d i am et er is si m il a r fo r a mo rp hous na tu re of th e si lic a . The st ro ng c ry st a lline
3 0 w t% a nd 4 0 w t % s a mp le . L ite r a tur e r e p or te d t ha t t he pe a k of si lic a is obs er ve d a t 2 h = 31. 9 ( I C DD #
c at alys t pr ep a re d b y pr ec ip it a tio n g el tec h ni qu e i s 89 -1 666) a t a lo wer le ve l of lo ad ing whi ch r e duc e s
2
9
stable d ue to st ron g i nt eracti on wit h t he silica a t hi ghe r c at al yst lo ad ing. The c al ci ne d sa mpl es
Table 2. Su rf ac e ar ea an d po r e vo lu m e of s il ic a- s uppo r t ed cop per chr om i t e.
2
B ET s ur f ace ar ea ( m /g )
2
BJ H S ur f ace are a (m / g)
3
P ore vol um e V (cm / g)
S amp l e
P ore di am et er D ( nm )
p
p
S iC u C r1 0
S iC u C r2 0
S iC u C r3 0
S iC u C r4 0
35 .9 9
76 .5 4
14 4. 91
96 .3 2
16. 36
43. 14
106 . 52
65. 71
0. 088
0. 36
0. 53
0. 45
3. 6
3. 6
14. 2
14. 3

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
P age 5 of 15 82
Figure 1. FE SEM im a ges of ( A) S iCu Cr 10 , (B ) S i CuC r2 0, (C ) S i CuC r3 0 and (D ) S i CuC r4 0 cat al ys t at 2 5 K
m agn i fi c a ti o n .
s h o w p e a k s a t 3 5 . 5 an d 3 7.5 wh ic h ar e t he mi x tur e of
t h e mo n o c lin i c s tr uc tu re o f Cu O ( ICDD# 89 -5 8 99) a nd
t e tr a g o n a l s p in e l st r uc tu re of Cu Cr O ( ICDD#2 1-
3 3
P lya sov a et al., ha s r ep or te d th at th e c oppe r
0
c hr om ite r ed uc es in to th e C u a nd C u a nd Cr O in
?1
2
3
2
4
a hyd r oge n a tm osph er e. The c ry sta ll ite si ze of the
C uCr O , C uO, C u O, C r O a nd C u a re c al cu l at ed by
f ull - width a t ha lf m ax im um ( FW HM ) f r om th e va lue s
30 ,3 1
0
8 7 4 ) in wh i ch sp i ne l p ro po rt io n i s mo re .
The
2
4
2
2 3
t e tr a g o n a l s p in e l s t ru ct ur e o f co pp er ch ro mi te c ont ai ns
c o p p e r a n d c h ro mi um at o ms pl a ced on t he t et r ah ed ra l
of di ff r a ct ion pe a ks, r es pe ct ive ly by S ch er r e r e qua tion ,
K k
32
a n d o c ta h e d ra l s p ac es .
L ¼
whe r e L is th e c ry sta ll ite si ze , K is the
bC os h
Fi g u re 4 s h o ws t he XRD d if fr ac t io n of t he r ed uc ed
fo r m o f s il ic a -s up p or t ed co pp er ch ro mi te c at al yst .
Af t e r re d u c ti o n , th e di f fr ac t io n pe ak ch an ge s po siti on
i n d i c a tin g th e c h a ng e i n co mp os it i on s. I n t he r ed uc ed
s a mp le , th e mo n o cl i ni c st r uc tu re of Cu O an d te tr a go-
n a l s p in a l Cu C r O st r uc tu re r edu ce s an d a ne w pha se
S ch er r e r c onst an t ( 0.89 ), k is th e wa ve le ngt h o f r a di-
a tio n in r ad ia nt, h is th e B ra gg s di ff r a ct ion a ngle , b is
th e F W HM. The c ry sta ll ite si ze s of c al ci n ed a nd
r ed uc ed c at al yst s a re ta bu la te d in Ta ble 4 a nd T ab le 5 .
The di ff r a ct ion pe a ks f or r ed uc ed S iC uCr 1 0 s am ple
is ve r y we ak du e to th e lo w a mo unt of c oppe r c hr om ite
pr e se nt in th e si lic a m at ri x a nd is not sho wn in the
r ed uc ed c at al yst .
2
4
fo r me t a lli c c u b ic Cu ( 2h = 43 .4 an d 5 0.1 ) ( I CDD#
8
7
3
9 -2 8 3 8 ), c u b ic C u O ( 2h = 36 .4 an d 65 .2 5) (I C DD#
2
8 -2 0 7 6 ) a n d rh omb oh ed ra l Cr O ( 2h = 24 .4 a nd
2
3
3 . 5 ) (IC DD# 8 4 -1 61 6) ar e o bse rv ed . Th e pos sib le
3
.1 e Thermo gravimetric analysis (TGA): F igur e 5
re a c ti o n s c h e me i s as f ol l ows
is th e TGA c ur ve of si lic a - supp or te d c oppe r c hr om ite
c at al yst . 10 wt% a nd 20 wt% c oppe r c hr om ite loa de d
sa m ple s sho ws ne a rl y 10 wt% of we igh t lo ss be low
H2
C u O:Cu C r O À! Cu þ Cu O þ Cr O þ H O
2
4
2
2
3
2

8
2
Pa g e 6 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
Figure 2. El e m en t al m ap pi ng of A ) S iCu Cr 20 , B) S i CuC r3 0 , C ) S i CuC r4 0 and D) EDX of S i CuC r4 0 cat al ys t i n FE SE M .
Table 3. EDX a na l ys i s of co pp er ch ro m ite con tai ni ng
s il i c a.
A tom i c W ei gh t %
S amp l e
C u
Cr
S i
O
Na
S iC u C r1 0
S iC u C r2 0
S iC u C r3 0
S iC u C r4 0
0 .3 7
1 .6 2
3 .3 8
5 .5 1
0. 34
2. 70
5. 77
9. 60
23 .8 3
23 .0 2
18 .2 7
15 .5 5
6 0. 37
6 0. 11
5 8. 23
5 4. 94
9. 42
8. 55
6. 79
8. 60
1
0 0 °C. T h is is d u e t o ad so rb ed mo is t ur e by t he si lic a
s a mp le s . S iC u Cr 40 sa mp le d oes no t sh ow a ny
m o i s tu re a d s o rp ti o n as t he si l i ca pr o po rt io n i s le ss in
t h e s a mp le a n d t he sa mp le sh ows a l ow am oun t of
3
4
Figure 3. XR D pat t ern s of cal ci ned cat al ys t s at d if f er e nt
l oadi ng . (X ) Mon oc l in ic C uO, ( O) Tet rag ona l s pi nal Cu Cr 2 -
O , ( d) S i li ca.
4
we ig h t lo s s (n e a rl y 4 wt %) up t o 7 00 °C. The
re s id u e a t 7 0 0 °C i s h ig he st f or 4 0 wt % l oa di n g a nd it
re d u c e s a s th e lo a di ng d ecr ea se s. Th i s i s ex pe c te d a s
t h e c o p p e r c h ro mi te i s st a bl e at hi g h t emp er at ur e a nd 3.1 f Hydrogen temperature programmed reduction
t h e we ig h t lo s s ta k es p la ce f ro m t he co nd en sa ti on of (H -TPR): De hydr a ti on of gl yc er ol ta ke s p la c e in
2
t h e s il ic a ma t rix .
th e pr e se nc e of a n a ci dic c at al yst . Li te ra tu r e r e por te d

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
P age 7 of 15 82
Figure 4. XR D pa tt er ns of r edu ce d ca tal ys t s at di ff er ent
l o adi n g . (c ) C u b ic Cu , ( y) Rh em bo he dr al Cr O , ( z) C ub i c
Cu O, (d) Si l i c a .
2
Figure 5. TGA cur ve fo r s i li c a-s u ppor te d cop pe r c hr o-
m i te cat al ys t .
2
3
ob ser ve d. I n th e c as e of S iC uCr 4 0, th e hydr og en
c onsu mp tion st ar t ed a bove 250 °C wit h a pe a k va lue
t h a t c o p p e r c h rom it e i s an ef f ect i ve ca t al yst f or
g l y ce ro l d e h y d rat i on . Pr e- r edu ce d co pp e r- ba s ed
c at a ly s t is a n in di sp en sa bl e p art of t he gl yc er ol
h y d ro g e n o ly s is . To ha ve h ig h ac t iv i ty , r educ t ion
c o n d it io n s wo u l d ha ve a g rea t i nfl uen ce o n ca ta ly tic
p e rfo rm an c e . T h e TP R p at te rn s of t he c al ci ne d
c at a ly s t s a re s h own i n Fi g ur e 6 . No pe a k is
o b s e rv e d fo r 1 0 wt % l oa di ng ca t al ys t ( Si Cu Cr 10 )
b u t fo r 2 0 wt % l oa de d sa mp le ( Si CuC r2 0) sho ws
h u mp a b o v e 2 5 0 °C an d i s co nt i nu ed t o 550 °C
t e m p e ra tu r e . T h a t me an s so me am ou nt of h ydr og en
h a s b e e n c o n s u med ab ov e 2 50 °C. Si mi l arl y, f or
Si C u Cu 3 0 c a ta ly s t, t he hy d ro gen co ns um pt io n st ar t ed
a b o v e 2 5 0 °C a n d a b ro ad p eak ne ar 45 0 °C i s
s t
of 320 °C f or 1 pe a k a nd 500 °C f or th e s ec on d
pe a k. The di ff e r en t pe a k pos iti on m ay be due to the
si ze of th e C uO spe c ie s in th e m at ri x. The s ur f ac e
C uO is m or e e as ily r ed uc ibl e th an th e bul k . X RD
a na lys is of 30 wt% a nd 40 wt% sa m ple ( Ta bl e 5 )
0
1?
sup por ts th e f or ma t ion of C u , C u a nd C r O . The
2
3
2?
c ha nge of c at al yti c pha se C u to C u ha s a gr e a t
?1
in flu enc e on gl yc er ol de hyd ra t ion.
3
5
Luo et al., pr op ose d th at th e m et al lic c op pe r is
pr im a r ily r es pons ibl e f or th e a ct iva ti on of hydr o-
?
ge na ti on whi le C u is f or de hyd ra t ion due to its
3
6 – 3 8
pr e se nc e of Le wis a ci d si te s.
Te n da m a nd
Table 4. Cr y st al li te s iz e ca lcu lat ed fr om XR D dat a fo r cal ci ned cat al ys t .
Cu O ( nm )
C uC r O (n m )
2 4
Sa m p le
2 h = 35 .6 2 h = 53 .6 4 2 h = 56. 44
2 h = 37. 5 2 h = 42. 2 2 h = 64. 72
Si C u Cr 10
Si C u Cr 20
Si C u Cr 30
Si C u Cr 40
12 .7 8
16 .4 4
22 .4 1
23 .4 4
-
12. 03
8. 83
9. 09
–
16. 83
19. 55
14. 48
15. 96
–
25 .6 1
16 .6 1
14 .2 4
10. 8
20. 45
24. 54
7. 74
7. 35
8. 07
10. 03
Table 5. Cr y st al li ze s iz e ca lcu l at ed fr om XR D dat a fo r red uc ed cat al ys t .
Cu ( nm ) C u O (n m )
C r O (n m )
2 3
2
Sa m p le
2 h = 43 .4
2 h = 50 .1
2 h = 36. 4
2 h = 65. 25
2 h = 24. 4
2 h = 33. 5
Si C u Cr 20
Si C u Cr 30
Si C u Cr 40
17 .2 4
13 .5 8
12 .8
–
23
23 .5 4
14. 99
17. 03
16. 94
1. 01
5. 38
3. 7
5. 35
3. 3
8. 96
37. 06
33. 36
20. 12

8
2
Pa g e 8 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
Te mp er a tu re pr og ra m me d de sor pt ion ) is c ar ri e d out
( Fi gur e 7) . I t in ve stig at es th e a mo unt of a ci d si te s a nd
th e st re ng th of a ci d di str ib utio n. I n th e NH - TP D
3
e xpe r im en t, a mm oni a is a dsor be d on a ci d s ite s of
c at al yst due to it s ba si c na tu re . The m a ximum
te m pe ra t ur e in te m pe ra t ur e ve r sus TC D si gn al plot
gi ve s in fo rm a ti on of a ci dit y of th e c at al yst a nd a r e a
und er th e de sor pt ion pe a k in dic a te s a ci dic st re ngth of
4
0
th e c at al yst . The r e a re th re e r an ge s of a m monia
2
2
de sor pt ion pe a k: we ak , in te rm e dia t e a nd st ro ng. I t is
sa id th at if th e a re a und er th e de sor pt ion c ur ve is la r ge
th en a ci d si te s of th e c at al yst is hi ghe r in th at r e gion.
S tr e ngth of th e sol id a ci d si te s wit hin TP D pr o fil e c a n
be c la ssi fie d by NH de sor pt ion te m pe ra t ur e r a nge s
3
f r om 100 –20 0 °C a s we ak ‘ 25 0–400 °C a s m ode r a te
a nd 40 0–650 °C a s st ro ng.
Figure 6. Te m p e ra tu r e P ro gr am m ed Re du cti on (TP R )
p r ofi le fo r s i l ic a -s u p po r ted co pp er ch ro m ite ca tal ys t .
The S iC uCr 2 0 sho wed a pe a k a t 12 0 °C in di ca t ing
-
1
th e pr e se nc e of we ak a ci d si te s ( 164 lm ol.g ) . This
r an ge of pe a k c or r esp onds to we ak a ci d si te s f or a
3
9
Ha n e fe ld h a v e di s cu sse d t he de hy dr at i on me c ha nism
o f v ic i n a l a lc o h o l ( Sch eme 1 ) . A Br on st ed ac id wil l
h e l p in th e e li min at io n of se co nd ar y al c oh ol whi ch is
s u b s e q u e n tl y d e hy dr at e d t o ac ro l ei n ( Sche m e 2) .
Le w is a c id mo r e ea si l y co or di n at es wi th pr im a r y
a l co h o l wh i ch is e as i ly ac ce ss ib le by t he ca t al yst si te s.
Th is wi ll le a d to t he f or mat i on o f h ydr o xy ac e to ne
4
0
sur f a ce hy dr oxyl gr ou p. The c onc e ntr a ti on of the s e
si te s is not im por t an t c at al yti ca l ly. W hi le S iC uC r 30
doe s not sho w a ny di sti nc t pe a k bu t a hu mp a t 150 °C
-
1
n d
in th e lo w r eg ion wit h a ci dit y 12 7 lm ol.g a nd 2
pe a k a t 32 0 °C in th e m ode r at e r eg ion wit h s ur f ac e
-1
a ci dit y 234 lm ol.g . Thi s pe a k is c los el y r el a te d to
sur f a ce a ci d pr op er ti es . S iC uCr 4 0 sho ws a br oa d pe a k
a t 58 3 °C but it st ar t s a bove 15 0 °C . The c umul at ive
1
8
(
H A ) o r a c et o l. V asi l i ado u et al., h ave men tio ne d
a b o u t th e s tr o n g a ds or pt i on of g ly ce ro l o n co ppe r via
i t s te rm in a l C- O bo n d, an d t he f act t ha t i t is not
a ffe c te d b y th e p res en ce o r ab se nc e of so l ve nt . B as ed
-1
sur f a ce a ci dit y f or S iC uCr 4 0 is 12 50 lmol .g .
Hig he r sur f a ce a ci dit y f or th e c at al yst is ve r y muc h
in flu ent ia l f or c at al yz ing th e gl yc er ol de hyd ra tion to
a ce to l. The na tu re of th e sur f a ce a ci dit y B ro ns te d/or
o n t h e a b o v e d is c u s si on we ar e p ro po si ng t ha t Cu O i s
2
t h e a c ti v e fo rm of t he ca t al ys t, wh ic h ac t s as Le wis
a ci d , a n d wi ll p ro d uce ac et ol i n gl y ce ro l de hyd ra t ion
re a c ti o n . He n c e , we ha ve d eci d ed t o r edu ce t h e c at a-
l y s t a t 3 5 0 °C fo r t he 4 h i n h ydr o gen at mo sp he r e.
Le wis a ci d si te s is not di sti nc t f r om th e NH - TP D
3
st udie s. Thi s m ay be du e to th e dr y st at e a dsor p tion of
NH ga s on c at al yst sur f a ce a t a hi ghe r te m pe r a tur e .
3
To ge t m or e in fo rm a ti on a bout a ci dic si te s, pyr idi ne
a dsor pt ion st udy by F TI R is c ar r ie d ou t.
3
(
. 1 g Ammonia temperature programmed desorption
NH -TPD): De h yd r at io n of g ly ce ro l i s gr e at ly
3
3.1 h Pyridine adsorption by FTIR: The nat ur e of
i n flu e n c e d b y a c id ic ca t al ys t/ su pp or t. To de te r mi ne
t h e a c id i c p ro p e rtie s of ca t al ys t t owa rd s t he f or ma t ion
o f a d e h y d ra ti on pr o du ct , NH - TPD ( Amm onia
a ci dic B rø nste d/ Le wis si te s of S ili ca sup por te d c oppe r
c hr om ite is c ha ra c te r iz e d by P yr idi ne a dsor be d F TI R
3
Scheme 1. Re act io n m ech ani s m on cat al ys t s ur face.

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
P age 9 of 15 82
Scheme 2. Re act io n s che me fo r deh ydr at i on o f gl ycer ol .
Figure 8. P y ri di ne IR s pec tr a of red uc ed s i li ca- s up po r te d
cop per chr om i t e cat al ys t wi t h di ff erent l oad i ng.
Ac id- c a ta lyz e d de hyd ra t ion of gl yc er ol ta ke s pla c e
in two wa ys. S ec on da ry a lc oho l de hyd ra t ion pr oc e e ds
via a r el a tiv el y st ab le in te rm e dia t e se c onda r y c a r bo-
c at ion , whi ch is ki ne tic a lly c ont ro lle d. The pr im ar y
a lc oho l de hyd ra t ion via Le wis a ci d m ec ha ni sm le a ds
to th e f or ma t ion of a ce to l, whi ch is th e th e r mody-
na m ic al ly a m or e st ab le pr od uct . The f r ee e ne r gy
c ha nge in th e de hyd ra t ion r ea c ti on of gl yc e r ol to
Figure 7. NH -T e m pe ra tu re P ro gr am m ed de s or pt i on pr o-
3
fi le fo r re d u c e d s i l ic a-s up po r ted co pp er ch ro m ite cat al ys t .
s p e c tra a n d a re s ho wn i n Fi g ur e 8 . I n t he c as e of
Si C u Cr2 0 a n d S i CuCr 3 0 ca t al ys t, no di s ti n gui she d
p e a k s a re o b s e rv ed wh er eas Si Cu Cr 40 ha s sho wn
m a ny s tr o n g p e ak s. Th at me an s t ha t t he c at al yst
s u rfa c e is a c id i c i n n at ur e d ue t o wh ic h i t ad sor be d
p y ri di n e v a p o u r. Th e Py ri d in e ad so rb ed I R ba nds ne a r
3- hy dr oxyp ro pyl via se c onda r y a lc oho l is - 70.2 kJ /mol
whe r ea s pr im a r y a lc oho l de hyd ra t ion to a ce tol is -
4 4
87. 4 kJ/ mo le .
-
1
-1
1
s i t e a n d th e b a n d at 1 480 cm i nd ic at es bo t h Le wis
6 0 5 c m a n d 1 4 5 4 cm ar e as si g ne d t o Le wi s a ci d
-1
3.2 Catalyst activity test
41 ,42
a n d Br ø n s te d a c i d si t e.
Th e ex i st en ce of hi gh
Le w is a c id s it e on Si Cu Cr 40 co mp ar ed t o Si CuC r 30 Ma ny r ea c ti ons a re ha ppe ni ng si mul ta ne ous ly s uc h a s
a n d S iC u Cr2 0 s e ems t o i nfl uen ce t he co nv ers ion of de hyd ra t ion, de gr a da tio n, pol ym er i za ti on, de hydr o-
g l y ce ro l a n d a ls o t he p ro du ct d is tr i bu ti on . A Br øns te d ge na ti on, e tc . ( Sc he m e 3 ) . The ty pe of re a c tion
a ci d wi ll h e lp i n el i mi na ti n g se co nd ar y a lc oho l de pe nds on m an y f ac t or s suc h a s ty pe of ca ta ly st,
wh e re a s a L ew is ac i d mo re ea si l y co or di n ate s to a r ea c ti on te m pe ra t ur e, c onc e ntr a ti on of c at al yst, c on-
43
p ri m a ry a lc o h o l th e re by wea ke ni ng t he C- O. I n f ac t , c en tr a tio n of gl yc er ol , st ir r ing spe e d, e tc . To m inim iz e
p ri m a ry a lc o h o l i s mo re r eac t iv e t ha n se con da ry th e e ff e c ts, we ha ve st udie d r ea c ti ons wit h the s am e
a l co h o l if a n o n -ac i di c co nd i ti on i s ap pl i ed .
in str um e nt wit h c onst an t st ir r ing spe e d.

8
2
Pa g e 1 0 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
Scheme 3. Re act i ons of gl ycer ol i nt o di ff erent pr oduc t .
I n th e g ly c e ro l de hy dr at i on r eac t io n, f ou r ca t eg or ie s
o f re a c ti o n s a re f or med si mu l ta ne ou sly . One is
o l i g o me ri za t i o n , w hi ch l ea ds t o n on- v ol at il e p r oduc ts .
Se co n d is d e h y d rat i on , an d t he ot h er s ar e t hr ee c ar bo n
45
a t om c o n ta in i n g p ro du ct s. Th e t hi r d i s t he d eg ra da -
t i o n p ro d u c t wh ic h i s l es s t ha n 3 C at o ms c ar bo n
4
6
c o mp o u n d s li k e ac et al d eh yd e, ac et i c ac i d, et c . The
fo u rt h c a te g o ry pr o du ct s ar e t he h ydr o gen and wa te r
wh i ch d o n o t c o nt a in ca rb on at o m i n t he ir mo le c ula r
4
7 ,4 8
s t ru c tu re .
Am on g al l t he p ro du ct s, o ne of th e
d e h y d ra ti on p ro d u ct i s ac et ol ( di st i ll ed p ro du ct) whi ch
i s o u r p ri me c o nc er n an d i s us ed as a r ef er en ce in
a n a ly s i s .
De h y d ra ti o n is an en do t he rmi c p ro ces s an d pr o-
c eed s mo r e ra p id ly at a h ig he r t emp er at u re . Gly ce r ol
d e h y d ra ti on wi th si l i ca- su pp o rt e d co pp er c hr om ite
c at a ly s t is s tu d i e d o ver t hr ee di f fe re nt ca t al ys t sa m ple
a t 2 2 0 °C. T h e rea ct i on i s ca rr i ed o ut wi th 2 0 vol %
a q ue o u s s o lu t io n o f gl y ce ro l wi th 1 gr am of re duc e d
c at al y s t s a mp le fo r t he d ur at io n of 3 h . Fi g ur e 9 is th e
p e rc e n ta g e o f g ly ce ro l co nv er si o n an d pe r ce nt ag e
Figure 9. S cre e ni ng of di ff erent s i li ca- s uppo r t ed c op pe r
chr om i t e cat al ys t . R eact io n con di t io ns : Gl yce rol : Wa te r
2
0: 80 (v ol %/ vol % ), R e act i on t em per atu re 220 °C , Ca t al y st
am ou n t 1 g and R eact io n dur at i on 3 h.
The a ce to l se le c tiv ity in cr e a se s a nd is hi gh es t f or
s e l ec ti v ity o f d is t i ll e d pr o du ct f or d if fe re nt si lic a - S iC uCr 4 0 whi ch is ne a r 70 %. Thi s is e xpe c te d a s the
s u p p o rte d c o p p e r ch ro mi te ca t al ys t. Her e HP LC lo ad ing of a ct ive c om poun ds ( co ppe r c hr om ite ) into
t e ch n iq u e is u s e d t o de t er mi ne t he p ro du ct com po si- si lic a m at ri x in cr e a se s m or e a ci dic si te s ge ne ra te d on
t i o n s . Ac e to l p ro d uct i on i s t he ma in pr o du ct t ar ge t of th e c at al yst sur f a ce whi ch a re r es pons ibl e f or c a ta lytic
4
9
o u r o b je c ti v e . H enc e p ro du ct ch ar ac te ri z ati on is de hyd ra t ion. The se le c tiv ity of a ce ta l de hyde is
c o mp ar ed wi th re f er enc e t o ac et ol y ie ld . Th e r es ult s a lm ost si mi la r f or th e th re e c at al yst sys te m a nd is
a re s h o wn fo r th r ee ca t al ys t sy st e m as n o d ist ill e d be lo w 5%. B ut a not he r c om poun d se le c tiv ity ( by-
p ro d u c t is o b ta i n e d f or Si Cu Cr 10 . Th i s ma y b e du e to pr od uct s) is hi ghe st f or S iC uCr 2 0 whi ch is ne a r ly 70%
t h e a b s e n c e o f a c t iv e si t es o f t he ca t al ys t. G lyc e ro l a nd lo wes t f or S iC uCr 4 0 whi ch is ne a rl y 25%. The
c o n v e rs io n is h ig h es t r eac he d 10 0 % f or Si CuC r 40 lo wer c ont en t of a ce to l se le c tiv ity a nd f or ma tio n of
c at a ly s t a n d is lo wes t f or Si Cu Cr 30 ca t al ys t. I n th e by- p ro duc ts wit h S iC uCr 2 0 a nd S iC uCr 3 0 sa m pl es a r e
c as e o f 3 0 wt % ca t al ys t mo re vi s co us r esi d ue is le f t due to it s lo w c ont en t of a ci dic si te s ( 164 a nd
-
1
a ft er re a c ti o n s wh i ch ma y be o li go me ri c pr o du ct s due 234 lm ol.g r es pe ct ive ly ) in NH - TP D a nd abs e nc e
3
t o wh i ch g ly c e ro l co nv er si o n i nt o d is ti l l ed pr od uct of B ro nste d a nd/ or Le wis a ci d si te s in th e p yr idine
re d u c e s .
a dsor be d F TI R a na lys is. At lo wer lo ad ing, by- pr odu ct s

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
P age 11 of 15 82
Figure 10. Ef fe c t of r eac ti on te m per at ur e o n Si C uC r40
cat a l y s t .
Figure 11. Eff e ct of cat al ys t am o unt on S iC uC r4 0
cat al ys t .
a re fo rm e d in h ig h e r am ou nt s be ca us e si l i ca sup por t is
n o t fu l ly c o v e re d by t he co pp er ch ro mi te . W he n c op- a re use d a nd th e r ea c ti on is c ont inue d up to 3 h in a ll
p e r c h ro mi te lo a d i ng i nc re as es , by - pr od uc ts de c re a se , c as es . I t is obs er ve d th at th e c onve r si on of glyc e r ol
a n d a s a re s u lt, ma in p ro du ct ac et ol se l e ct ivit y in cr e a se d f r om 76 to 100 % wit h a n in cr e a se in ca ta ly st
i n c r e as e s . In lo w er l oa di ng , t he r edu ci b il i ty of th e we igh t f r om 0.5 to 1.5 g. The se le c tiv ity of a c e tol
c at a ly s t a ls o p la y s a k ey r ol e i n pr o du ct se l ect i vit y a nd in iti al ly in cr e a se d f r om 56 to 70% f or a n in cr ea s e in
g l y ce ro l c o n v e rs io n. I n g ly ce ro l de hy dr at i on , hi ghe r c at al yst we igh t f r om 0.5 to 1 g, bu t a ft e r tha t, it
a ci d i c s it e s o f o u r sy nt h es iz ed ca t al ys ts ar e f ou nd to be r ed uc es to 63% f or 1.5 gm of c at al yst lo ad in g. The
a c ru c i a l p a rt o f pr o du ct se l ect i vi t y. So Si CuC r 40 is de c re a se in a ce to l pr od uct m ay be du e to th e f or ma tio n
fo u n d to b e th e b e st ca t al ys t f or g ly ce ro l de hyd ra t ion. of si de pr od uct s a t hi ghe r c at al yst lo ad in g. The
in cr e a se in gl yc er ol c onve r si on wit h in cr e a si ng
3
. 2 a Effect of reaction temperature on catalyst
c at al yst lo ad ing c oul d be du e to th e m or e a va ila ble
a ct ive si te s on th e c at al yst sur f a ce f or th e glyc e r ol
de hyd ra t ion, whi ch le a ds to e xc es s de hyd ra tio n to
f or m a ce to l a nd lo wer de gr a de d pr od uct s.
activity: F ig u re 10 sh ows t he ef f ect of r ea c ti on
t e m p e ra tu r e o n c a t al ys t ac t iv i ty wi th Si Cu Cr 4 0 in 20
v o l % g ly c e ro l s o l ut i on wi th 1 gr am r edu ce d c at al yst
4
fo r 3 h in th e ra n ge of t emp er at u re 18 0 –24 0 °C .
A t 1 8 0 °C g ly c e r ol co nv er si o n i s 47 % an d i t r ea c he s 3.2 c Effect of substrate ratio on catalyst
i t s m a x im u m (1 0 0 %) ab ov e 22 0 °C. At 2 20 °C gl yc - activity: The e ff e c t of gl yc er ol c onc e ntr a tions on
e ro l c o n v e rs io n a n d ac et ol se l ect i vi t y r eac he s a m ax - th e c onve r si on of gl yc er ol a nd se le c tiv ity pat te r n is
i m u m o f 7 0 % wi th an i nc re as e i n t emp er at u re . B ut a t st udie d in th e r an ge of 10 –40 vo l% gl yc er ol w ith 1 g
2
4 0 °C, a c et o l s e l ect i vi t y dr o ps dr as t ic al l y f ro m 70 % S iC uCr 4 0 c at al yst a t 22 0 °C f or 3 h a nd th e r es ults a r e
t o 24 .2 % d u e to an i nc re as e f or mat i on o f by- p ro d- sho wn in F igu re 12.
5
0
u c t s. T h is te s t in di ca t es t ha t at a hi g he r t emp e ra t ur e
c at al y s t fa v o u rs C- C b ond cl e ava ge an d o xi d at ion is
c ar ri e d o u t in s t e ad of de hy dr at i on . Th i s co ul d be
The c onve r si on of gl yc er ol r em a ins c onsta nt a t
00 % whi le th e se le c tiv ity of a ce to l in cr e a se d f r om 62
1
to 69 % wit h th e in cr e a se in gl yc er ol c onc e nt r at ion
f r om 10 –20 vo l%. I nte r e sti ngl y, a ce to l se le c tivit y
de c re a se d f r om 70 to 35. 46% a t 40 vo l % glyc e r ol
sol uti on. Ac et ol se le c tiv ity de c re a se s a s un de si re d
r ea c ti on pr od uct m ay f or m a t hi gh c onc e ntr at ion of
gl yc er ol a que ous sol uti on. Ac co rd ing to F igu re 12, the
hi ghe st se le c tiv ity of a ce to l is ob ta ine d a t 20 vol% of
gl yc er ol c onc e ntr a ti on whi ch is f oun d to be the opti -
m um gl yc er ol c onc e ntr a ti on.
9,5 1
p ro mo te d b y th e a ct i ve p has es o f t he ca t al ys t.
The
m a j o r b y -p ro d u c ts f or med ar e ac et al d eh yd e du e to
C -C b o n d c le a v a ge of g ly ce ro l an d ox i da tio n of
a cet a ld e h y d e le a d s t o f or m ac et i c ac i d f or ma t ion.
Th u s , th e h ig h t emp er at u re i s o nl y f avo ur a ble f or
a cet o l o x id a t io n b y Si Cu Cr 40 ca t al ys t.
3
. 2 b Effect of catalyst amount on catalyst
activity: T h e e ff ect o f ca t al ys t l oa di ng on th e
d e hy d ra t io n re a c t io n i s st u di ed i n t he r ange of
0 . 5 – 1 .5 g c a ta ly s t at 22 0 °C an d t he r esu lt s a re
p re s e n te d in F ig u r e 11. 20 vo l % gl y ce ro l so lu tio ns
3.2 d Effect of reaction time on catalyst
activity: The e ff e c t of th e r ea c ti on ti me on c a ta lys t
a ct ivi ty is st udie d wit h opt im iz e d te m pe r a tur e

8
2
Pa g e 1 2 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
Figure 12. Ef fe c t of s ub s tr ate r ati o on S iCu Cr 40 cat al ys t .
Figure 14. XR D o f red uced and s pen t cat al y st o f
S i CuC r4 0 cat al ys t . (c) C u, (y ) C r O , (z) C ubi c Cu O,
2
3
2
(
d) s i li ca.
Figure 13. Pe rc e n ta ge pr o du c t s el ect ivi t y of pr oduct s
af t er 6 0 m i n i n t er v al up to 3 h r eac tio n ti m e.
Figure 15. R a m an s pec t ro s copy of red uced and sp e nt
S i CuC r4 0 cat al y s t .
(
2 2 0 °C) fo r 2 0 v ol % gl y ce ro l co nc en tr at i o n wit h
o p t i mi ze d (1 g m) ca t al ys t an d t he r esu l ts ar e sho wn in
Fi g u re 1 3. S a mp le s ar e co l le ct ed af t er 6 0 mi n in te rv al
a n d a re a n a ly s e d by HPL C. Th e f ra ct io ns ar e col le c te d
a ft e r re a c h in g th e d esi r ed r eac t io n t emp er at ur e . The
fir s t fra c t io n (6 0 mi n) sh ows t he hi g he st a ce to l
s e l e ct iv it y (6 5 %) wh ic h r edu ce s t o 35 % in th e
s e co n d fra c t io n an d 1 7% i n t he l as t f ra ct io n. Ac et ic
a ci d s e le c ti v ity is l es s t ha n 5 % an d i s ab se nt i n th e la st
fr a c tio n . In th e s ec on d f ra ct io n ac et al d eh yd e sho ws
gl yc er ol c onve r si on de c re a se s f r om 100 % to 93.3%
whe r ea s th e m ai n pr od uct a ce to l se le c tiv ity a ls o
de c re a se s f r om 70 % to 19. 4%, r es pe ct ive ly . T he s up-
po rt S iO in c at al yst S iC uCr 4 0 is th er m al ly st a ble but
2
a ct ive C u ha s a te nd en cy to lo se or a ggl om er a te a f te r
e ac h c at al yti c te st . Thi s m ay be th e r ea so n be hind the
de c re a se in th e a ce to l se le c tiv ity of th e glyc e r ol
de hyd ra t ion. The se fi ndi ngs in dic a te th at a ll ca ta ly sts
a re hy dr othe r ma l ly st ab le a nd no c oke f or ma tio n
oc c ur s in th e r eu se d c at al yst ba se d on XRD a nd
R am a n spe c tr os cop y.
5
2
2
8 % s e le c ti v ity .
3
. 3 Recycle of the catalyst
At th e e nd of th e r ea c ti on, a ll th e c at al ys ts a r e
r ec ov er e d, fi lte r e d a nd wa she d wit h m et ha nol a nd dr ie d
in a va c uum ov en un til c onst an t we igh t. XR D a na lys e s
Fi n a ll y , th e c a ta ly st ( Si CuC r4 0) st a bi l it y i s ev a lua te d
u n d e r o p ti mu m c on di t io ns . Th e ex pe ri me nt sh ows th at

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
P age 13 of 15 82
o f t he s p e n t a n d re du ce d Si Cu Cr 40 ca t al ys t ar e sh own in Acknowledgement
Fi g u re 1 4. XR D pa t te rn sh ows t ha t Cu O ( 2h = 36. 4)
t h e a c ti v e c o mp o u nd i s ab se nt i n sp en t ca t al ys t th ro ugh
m e t a lli c Cu (2 h = 4 3.4 an d 50 .1 ) i s st i l l pr es en t. As th e
2
The aut h or s gr at efu ll y ack now l edge t he s t at e o f t he a rt
t es t ing fac il i ty at C ent r al In s tr um en t at ion F aci l i t y o f Bi r l a
In s ti t ut e of Te chn ol ogy Mes r a.
a ct i v e c o mp o u n d Cu O i s ab se nt , t hi s wi ll l os e it s c at -
2
a l yt ic b e h a v io u r. Th e ca t al ys t sh ou l d be r egen er a te d
a ft er e a ch re a c ti o n . I n Fi g ur e 15 Ra man sp ec tr os copy References
s h o ws th a t th e r e is no co ke f or mat i on on t he c at al yst
1
2
3
4
. Ko ng P S , Kh eir edd in e M, Moh d W and Wa n A 2 01 6
C on ver s io n of cru de and pur e gl ycer ol i nt o der iv at i v e s:
A fea s ib il i ty eva l uat i on Renew. Sustain. Energy Rev. 63
s u rfa c e a fte r d e h y dr at i on r eac t io n.
T h e o x id i s e d c a t al ys t ( Si CuC r4 0) i s u sed f or gl yc -
e ro l d e h y d ra ti on an d i t gi v es 2 3.3 % ac et ol pr od uct ion
wi t h g ly c e ro l c o nv er si o n of 62 %. Al l t he ab ove di s-
5
3 3
. Meh e r L C , Dh a rm ag add a V S S and Nai k S N 2 00 6
Op t i m iz ati on of al kal i -c at al yzed t rans e s t eri fi ca t i on o f
Pongamia pinnata oi l fo r pr oduc t io n of bi o di e s e l
Bioresour. Technol. 97 139 2
. Xi ao Z, Li C , Xi u J , Wa ng X, Wi l l i am s C T an d L ia n g
C 201 2 C he m i cal In s igh ts i nt o t he rea ct ion pat hwa y s o f
g l ycer ol hyd rog eno ly s i s ove r C u – C r cat al ys t s J. Mol.
Catal. A Chem. 365 24
. Yu e C J , Gan M M, Gu L P and Zh uan g Y F 2 01 4
In s i tu s ynt hes i zed nan o- cop per ove r ZS M-5 f or t he
cat al yt ic deh ydra t i on of gl ycer ol und er m i ld co nd i t io n s
J. Taiwan Inst. Chem. Eng. 45 144 3
. Mag a r S , Kam b l e S , Moh an raj G T, J ana S K an d Ro d e
C 201 7 S ol i d-aci d -ca ta lyz e d et her ifi cat i on of g ly c e ro l
t o pot en ti al fu el add it i ves Energy Fuels 31 122 7
. B e hr A 200 8 The fu t ur e of gl ycer ol . New us age s f or a
v ers a ti l e raw m at er i al . B y Mar i o P agl i aro and Mi c h el e
R os s i ChemSusChem 1 6 5 3
1
?
c u s s io n s u p p o rts t he f un ct io ns of Cu
5
p ro d u c ti o n .
i n a ce to l
3
4
. Conclusions
Si l i c a -s u p p o rt e d co pp er ch ro mi te ca t al ys t we r e syn -
t h e si s e d b y a c id h ydr o ly si s o f so di u m si l i cat e. The
B ET s u rfa c e a re a f or t he sy nt h es iz ed ca t al ys t is m ax -
i m u m fo r S iC u Cr 30 f ol l owed by Si Cu Cr 40 . T he e le -
m e nt a l ma p p in g s h ows ev en di s tr i bu ti on of co ppe r a nd
c h ro mi u m th r o u g h ou t t he ca t al ys t. EDX r esu l t sho wed
t h e in c r e as i n g a to mic pe rc en t age of co pp er and c hr o-
m i u m wi th a n in c re as in g am ou nt of l oa di ng. XR D
s p e c tra o f c a lc in e d ca t al ys t sh owe d t he t et r ag ona l
s p i na l s tr u c tu re o f Cu Cr O an d mo no cl i ni c C uO.
5
6
7
8
. P a gl i aro M, C ir im i nn a R , Ki m ura H, R os s i M an d De l la
P i na C 200 7 F rom gl yc ero l t o val ue- adde d pr od u c t s
Angew. Chem. Int. Ed. 46 443 4
2
4
XR D s p e c tra o f red uc ed ca t al ys t sh owe d t he pr e se nc e
0
o f C u , C u a n d Cr O . Th e r edu ci n g t empe r a tur e
?1
2
3
. S u t hagar K, S h ant hi
K
and S e l vam
P
2 01 8
wa s 3 5 0 °C d e te r mi ned b y H - TPR an al y si s whe r e
2
Hy dr oge nol ys i s of gl ycer ol ov er s i li c a-s u ppor te d c op -
p er- nano c at al ys t : Eff e ct of pr eci pi t at ing -ag e nt a nd
cop per m et al -l oadi ng Mol. Catal. 458 307
. Das ari M A, Ki at s i mk ul P P , S u t te rl in W R and Su p pe s
G J 200 5 Low -pre s s ure hyd rog eno ly s i s of gl yc er o l t o
p ro pyl ene gl yc ol Appl. Catal. A Gen. 281 225
?
2
?1
C u io n c o n v e rte d t o Cu i on . Th e h ig he st a mo unt
-1
o f a c id i c s it e s ( 12 50 lmo l. g ) was ob t ai ne d f or
S i C u Cr4 0 ) 4 0 wt % ca t al ys t i n NH - TPD st udie s.
9
(
3
Py rid i n e a d s o rp ti o n FT IR sh owe d st r on g Le wi s a ci d
s i t e s fo r re d u c e d ca t al ys ts . Cu pr ou s ox i de wh i ch a ct s
a s L ew is a c id s it e s on ca t al ys t su r fa ce was r espo nsi ble
fo r h ig h a c et o l s el e ct iv it y i n gl y ce ro l de hyd ra t ion.
Gl y ce ro l d e h y d rat i on was ca rr i ed ou t wi th f our di f-
fe re n t c a ta ly s t s at di f fe re nt t emp er at u re s. The opt i-
m i z e d re a c ti o n te mp er at u re was 22 0 °C f or 3 h wit h 1
g m c a ta ly s t a n d 2 0 v ol % aq ue ou s gl y ce ro l so l u tio n f or
1
0. Li ang C , Ma Z and Di ng L 2 009 t em pl at e pr epa r at i o n
of hi ghl y act i ve and s el ect i ve C u– C r cat al y st s wi t h
hi gh s ur face are a fo r gl yc ero l hyd rog eno l ys i s Catal.
Lett. 130 169
11. Hu ang Z, C ui F , Kan g H, C hen J , Zhan g X and Xi a C
200 8 Hi ghl y di s per s ed s i li c a-s u ppor te d c op pe r
nan opar t i cl es pr epa red by p rec ip it at io n –G el Me t ho d: A
S i m ple but Effi ci ent and S t abl e C at aly s t fo r G ly c er o l
Hy drog en ol ys i s Chem. Mater. 20 509 0
3
h . S iC u Cr4 0 s h owe d t he h ig he st ac et ol se l e ct ivit y
(
7 0 %) a n d n e a rly 10 0 % gl y ce ro l co nv er si o n. The 12. Ki m N D, Oh S , J oo J B , J ung K S and Yi J 201 0 T he
pr om ot io n eff ect of C r on cop per cat a ly s t i n
XR D a n a ly s i s o f t he sp en t ca t al ys t sh owe d t he pr e s-
?
1
hyd roge nol ys i s of gl ycer ol t o pr opyl ene gl yc o l Top.
Catal. 53 517
e n c e o f c o p p e r me ta l bu t t he ab se nc e o f Cu io n
i n d i c a te s th e lo s s of ac t iv i ty af t er t he r eac t ion . The
c al c in e d S iC u Cr4 0 ca t al ys t ( ox id is ed f or m) sho wed
2
6
1
3. R ode C V, Gh alw adka r A A, Man e R B , Hen g ne A M,
J adk ar S T and B ir adar N S 201 0 S el e c ti v e
hyd roge nol ys i s of gl ycer ol t o 1, 2-p r opa ned i ol : Co m-
par is o n of bat ch and con t i nuou s pr oce s s op er a ti o ns
Org. Process Res. Dev. 14 138 5
3 . 3 % a c et o l s e le ct iv it y an d l ow g ly ce ro l co nve r si on
2 %. S p e n t S iC u Cr 40 ca t al ys t al s o sh owe d l ow a ce to l
s e l ec ti v ity (1 9 . 4 %) wi th 93 .3 % g ly ce ro l co nv e rs ion.
He n c e , c u p ro u s i on i s t he r eas on f or h ig h a ce to l
s e l ec ti v ity fo r g ly c er ol co nv er si o n.
1
4. P ant al eo G, Li ot ta L F , Ven ezi a A M, Deg ane l l o G,
Ezzo E M, El Kh erbaw i M A and At i a H 200 9 Su p po r t
eff ect on t he s t ruct ur e and C O oxi da ti on act i vi t y o f Cu -

8
2
Pa g e 1 4 o f 1 5
J. Chem. Sci. (2 019) 1 31: 82
C r m i x ed o x i d e s ov er A l O an d S iO Mater. Chem.
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2
3
2
Phys. 114 6 0 4
1
1
1
Yo k o t a M 2 0 0 8 V ap or - ph as e r eac tio n of po lyo ls ove r
c o pp e r c at a ly s t s Appl. Catal. A Gen. 347 18 6
6 . C h iu C -W , Da sa ri M A , S up pes G J an d S ut ter l in W R
201 2 Et hano l deh ydro gena t io n t o et hyl acet at e by u si n g
cop per and cop per chr om i te cat al ys t s Chem. Eng. J.
179 209
2
re a ct i v e d i s ti l l at ion AIChE J. 52 35 43
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C uC r O nan opa rt i cl es : S ynt he s i s , cha ract eri za ti o n a nd
2 4
7 . B ra g a T P, Pi n h ei r o A N , Tei xe ir a C V an d V alen ti ni A
0 0 9 De h y d ro g en at ion of et hy lbe nz en e in th e p res en ce
t hei r m or phol ogi cal and s i ze eff ect s on t he ca t a ly t i c
t herm a l dec om po s i ti on o f am m on ium per c hl or at e Solid
State Sci. 37 72
2
o f C O 2 u s i n g a ca tal ys t s yn t he s ize d by po l ym er i c
p re cu r s o r m et h o d Appl. Catal. A Gen. 366 19 3
8 . Va s il i a d o u E S an d Lem o ni do u A A 20 11 I nv es t ig at ing
t h e p e rfo rm a n ce an d de act i va ti on be ha vio ur of s i li ca-
s u p p o rt e d c o pp e r ca tal ys ts in gl yc er ol hy d r ogen ol ys i s
Appl. Catal. A Gen. 396 1 7 7
33. Kh as in A A, Yu r’ev a T M, P l yas ova L M, Ku s t ov a G
N, J obi c H, Iv anov A, C he s al ov Y A, Zai kov sk i i V I ,
Kh as in A V, Dav ydov a L P and P arm on V N 2 00 8
Mec hani s t ic fea tu r es of red uct io n of cop per c hr om i t e
and s t at e of abs o r bed hyd rog en i n t he s t ruc t u re o f
red uced cop per chr om i te Russ. J. Gen. Chem. 78 2 20 3
1
1
9 . M i y az awa T, Ku su no ki Y , K un im or i K an d To m i s hi ge
K 2 0 0 6 Gl y c er ol co nv er s io n in th e aq ue ou s s ol u t io n 34. Kaw am ot o A M, P ard ini L C and R ezend e L C 2 00 4
u n d er h y d ro g e n o ve r Ru /C ? an io n- ex ch an ge res i n and
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0 . C h am i n an d J , D jak ov i tc h LA , G all ez ot P , Mar io n P , 35. Luo M- F, Zho ng Y- J , Yu a n X- X and Zhen g X- M 1 99 7
S ynt hes i s of cop per chr om i t e cat al ys t Aerosp. Sci.
Technol. 8 591
2
2
2
Pi n e l C a n d R o s ier C 2 00 4 G lyc er ol hy dr o g en o ly s i s on
h e te ro g e n eo u s ca tal y s ts Green Chem. 6 35 9
TP R and TP D s t ud i es of C uOC eO cat al ys t s f or l ow
2
t em per atu re C O oxi da ti on Appl. Catal. A Gen. 162 1 21
1 . Li K T, Li J Y an d Li H H 20 17 Co n ve rs i on of gl yc ero l 36. Xi ao Z, Wa ng X, Xi u J , Wa ng Y, Wi l l ia m s C T a nd
0
Li ang C 201 4 S yne rg et i c eff ect bet we e n C u an d Cu
?
t o l ac t i c a ci d o ve r Cu – Zn –A l an d Cu –C r ca ta ly s ts i n
a lk a l i n e s o l u t i o n J. Taiwan Inst. Chem. Eng. 79 74
2 . Su p r u n W , Lu tec ki M, H abe r T an d P app H 200 9
i n t he C u-C r cat al ys t s fo r hyd roge nol ys i s of g ly c e ro l
Catal. Today 234 200
Ac i d ic c at a ly s ts f or th e de hy dr at io n of gl ycer ol : 37. B raga T P , Es s aye m N and Val en ti ni A 201 7 Co r re -
Ac t iv i t y a n d d e act iv at ion J. Mol. Catal. A Chem. 309 l at ion bet we e n t he bas i ci t y of C u-Mx Oy- Al O ( -
2
3
7
1
M = B a, Mg, K or La) oxi de and t he c at a ly t i c
per for ma nc e i n t he gl ycer ol con ver s i on fr om a ds or p -
t io n m i croc al or im et r y cha ract eri zat i on J. Therm. Anal.
Calorim. 129 65
2
3 . Sh r ee V a n d Se n A K 20 18 S tu dy of th er m al an d fl am e
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2
4 . M an e R B a n d Ro d e C V 20 12 Co n ti nu ou s de hyd r at i on 38. C e´ l eri er S , Mor is s e t S , B a t onne au- gen er I, B e l i n T ,
a n d h y d ro g e n ol ys i s of gl yc er ol o ve r no n- c hr om iu m
c o pp e r c at a ly s t: Lab or a to r y- s c al e pr o ce s s s tu di es Org.
Process. Res. Dev. 16 10 43
Yo unes K and B at io t- dupe yr at C 201 8 G ly c er o l
deh ydra t i on t o hyd rox yac eto ne i n gas pha s e ove r c op -
per s upp or t ed on m ag nes i um ox i de(h ydro xi de)fl uo r i de
cat al ys t s Appl. Catal. A Gen. 557 135
2
2
2
5 . R ak s a p h o rt S, P eng pa n ic h S an d H un so m M 201 4
Pr o d u ct s Di s t ri bu tio n of gl yc er ol hy dr o g en ol y s i s ove r 39. Tend am J and Han efe ld U 201 1 R enew abl e che mi c al s:
s u p p o rt e d c o c ata ly s ts in a li qu id ph as e Kinet. Catal. 55
5 6
6 . Ha o S, Pe n g W , Zh ao N an d X iao F 201 0 40. R odr ´ı gue z- Go nz a´ l ez L, Her m es F , B ert m er M, Ro d r ´ı -
Deh ydro x yl at i on of gl ycer ol and pol yo ls Chem-
4
SusChem 4 1 017
Hy d ro g e n o l y s is of gl yc er ol to 1, 2- pr op an ed i ol cat -
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Tech. Biotech. 85 14 99
7 . Va n k u d ot h K, G utt a N , V eli s oj u V K , Mut yal a S ,
gue z-C as t el l o´ n E, J i m e´ nez -L o´ pez A and S i m on U 2 00 7
The aci d pr ope rt i es of H- ZS M-5 as s t udi ed b y NH 3 -
TP D and 27A l- M AS -N MR s pec tr os copy Appl. Catal.
A Gen. 328 174
4
1 2 4 0
2 3
Ay t a m H P a n d A ku la V 20 17 Cu Cr O de ri ve d by t he 41. Kr is h na V, Nar es h G, Ku ma r V V, S ark ari R , Pa d ma s ri
2
4
s o l -g e l m et h o d as a h ig hl y ac t iv e an d s el ec tiv e cat al ys t
fo r t h e c o nv e rs i on of gl yc er ol to 2, 6- di m et hy lp yrazi ne:
A b e ni g n a n d ec o- f ri en dly pr o ces s Catal. Sci. Technol.
A H and Ven ugo pal A 201 6 S ynt he s i s of 2, 6 -d im et h yl -
pyr azi ne by deh ydro cyc l iz ati o n o f aqu eou s gl yce ro l a nd
1, 2-p ropa n edi am i ne o ver C uC r O cat al ys t : R a t io na l i za -
t io n of act i ve s i te s by pyr i din e and fo rm i c aci d a ds or b ed
IR s t udi es Appl. Catal. B Environ. 193 58
7
8 . Ki n a g e A K, U par e P P , K as in a th an P , H wa ng Y K and
3 3 9 9
2
2
C h an g J S 2 0 1 0 S ele cti ve co nv er s i on of gl y c ero l t o 42. S t o sˇ i c´ D, B enni c i S , S i rot i n S , S t el m ach ow sk i P,
a ce t o l o v er s o d i um - d ope d m et al ox id e ca tal ys ts Catal.
Commun. 11 6 20
C out uri e r J L, Du bo i s J L, Tra ve rt A and Aur o ux A
201 4 Ex am i nat i on of aci d- bas e pr ope rt i es o f so l i d
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226 167
9 . Zh a n g B , Hu i S , Zh ang S , J i Y , Li W an d F a ng D 201 2
Ef fec t o f c o pp e r lo ad in g on te xt ur e, s tr u ct ur e and cat -
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Gas Chem. 21 56 3
0 . M o b in i S, M es h ka ni F an d Re zae i M 20 17 S u rfa ct ant -
201 0 Gas - pha s e deh ydr at i on of gl ycer ol t o a cr ol e i n
cat al ys ed by caes i um het er opo l y s al t Appl. Catal.
A Gen. 378 11
3
a ss i s t e d h y d ro th er m al s yn th es i s of Cu Cr O4 s pi n el
2

J. Chem. Sci. (2 0 1 9 ) 13 1: 82
P age 15 of 15 82
4
4 . Ni m lo s M R , Bl an ks by S J , Q ian X , H i m m el M E and
J o h n s on D K 2 00 6 Me ch an is m s of gl yc er ol deh ydra -
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50. Man e R B , Yam a guchi A, Mal awa dkar A, S h i ra i M a nd
R ode C V 201 3 Act i ve s i te s i n m odi fi ed cop pe r c at a -
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4
5 . M ar t in A a n d Ri ch t er M 20 11 O lig o m er iz ati on of gl yc-
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4
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4
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4
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4