P omo ing e ec o Sn on suppo ed Ni ca alys du ing s eam
e o ming o glyce ol
L. F. Bobadilla,†* F. Rome o-Sa ia, M. A. Cen eno and J. A. Od iozola
Depa amen o de Química Ino gánica e Ins i u o de Ciencia de Ma e iales de Se illa
(ICMSE). Cen o mix o CSIC - Uni e sidad de Se illa, 49 A . Amé ico Vespucio, 41092
Se illa (Spain)
† Cu en add ess: Ins i u o de Tecnología Química (ITQ). Cen o mix o CSIC-
Uni e sidad Poli écnica de Valencia, s/n A . de los na anjos, 46022 Valencia (Spain)
* Co esponding au ho : [email p o ec ed]
Abs ac :
The p omo ing e ec o Sn on he ca aly ic pe o mance o suppo ed Ni ca alys in he
eac ion o glyce ol s eam e o ming was s udied. The physico-chemical p ope ies o
he p epa ed samples we e in es iga ed by X- ay luo escence (XRF), BET su ace a ea,
in si u X- ay di ac ion (XRD), lase Raman spec oscopy, X- ay pho oelec on
spec oscopy (XPS), scanning elec on mic oscopy (SEM) and empe a u e
p og ammed oxida ion (TPO) echniques. The cha ac e iza ion esul s o he samples
a e educ ion ea men (in he same condi ions han he ac i a ion be o e ca aly ic
ac i i y measu emen s) e ealed he o ma ion o Ni-Sn alloy. The Sn-doped ca alys
exhibi ed a high ac i i y and i was demons a ed ha he Sn addi ion inc ease he
ca alys s abili y and du abili y by dec easing he coke deposi ion.
Keywo ds: Hyd ogen p oduc ion; Sn addi ion; Coke deposi ion
1. In oduc ion
Du ing he las decades impo an e o s a e ongoing o educe ossil uel
dependency and g eenhouse gas emissions. Among he di e en possibili ies o ind a
iable op ion, he use o hyd ogen as an ene gy ca ie is conside ed o be an in e es ing
al e na i e o he u u e and could ha e a c ucial ole in educing a mosphe ic
pollu ion. Biomass is conside ed as one o he mos a ac i e enewable sou ce o
hyd ogen p oduc ion and nume ous s udies a e being di ec ed owa d he de elopmen
o no el echnologies o p oduce hyd ogen om biomass [1-4]. S eam e o ming o
glyce ol is an impo an app oach o hyd ogen p oduc ion om biomass. Glyce ol is
he main by-p oduc gene a ed in he biodiesel p oduc ion. Biodiesel is one enewable
bio uel ob ained by ca aly ic ans-es e i ica ion o iglyce ides wi h me hanol [5].
Abou 10 w .% o glyce ol can be p oduced du ing he con e sion o ege able oils in o
biodiesel. The use o glyce ol o hyd ogen gene a ion is a e y ad an ageous op ion
since i s use would dec ease he p ice o biodiesel making i mo e compe i i e [6].
The o e all eac ion o glyce ol s eam e o ming is gi en by he ollowing equa ion:
C3H8O3 + 3H2O → 3CO2 + 7H2 (1)
which can be exp essed as a combina ion o glyce ol decomposi ion (2) and he wa e -
gas shi eac ion (3):
C3H8O3 → 3CO + 4H2 (2)
CO + H2O ↔ CO2 + H2 (3)
Theo e ically, a maximum o 7 moles o H2 pe mol o glyce ol can be p oduced,
al hough his a io depends on he eac ion condi ions such as empe a u e, p essu e and
s eam- o-glyce ol s eam a io.
Al hough he glyce ol s eam e o ming p ocess is e y a ac i e and i could be
de eloped on an indus ial-scale, i has some challenges ha mus o be o e come in
o de o accomplish i s e ec i e comme cializa ion. Fo example, he p ocess is an
endo he mic eac ion and equi es high empe a u es inc easing he ope a ion cos s.
Besides, he ca alys deac i a ion by coke deposi ion is also an issue since i a ec s
hyd ogen yield and long e m ope a ion. Wi h he aim o o e coming hese challenges,
he de elopmen o ac i e, s able and inexpensi e ca aly ic ma e ials is manda o y.
Ca alys s con aining g oup 8-10 me als such as Ni [7-12], Co [13-16], P [17-21], Ru
[22-24], Rh [25], Pd [26] o I [27] on di e en oxides ha e been la gely in es iga ed as
ac i e ca alys s o glyce ol s eam e o ming. Ni-suppo ed is one o he mos p omising
ac i e me als o such an applica ion because o i s high ac i i y, low cos and wide
a ailabili y. Howe e , Ni-based ca alys s su e deac i a ion by coke deposi ion on he
ca alys su ace ha block ac i e si es and a ou side eac ions. Deac i a ion o nickel-
based ca alys s by sin e ing o nickel c ys alli es is ano he impo an d awback.
P omo ing nickel ca alys s wi h a second me al has been p o en o be one o he mos
p omising app oach o ob ain mo e s able and op imal ca alys s [28]. Bime allic
ca alys s comp ising Sn as a Ni p omo e ha e been p o ed o ou pe o m Ni
monome allic ca alys in s eam e o ming p ocesses [29]. The coke deposi ion can be
ma kedly educed by using Sn-doped ca alys s in he s eam e o ming eac ion o
gene a e hyd ogen om hyd oca bons. Sn alloyed wi h nickel p e en s he o ma ion o
nickel a om ensembles, which a e he esponsible o he coke o ma ion, and a oids he
di usion o ca bon o o m la ge coke agglome a es [30]. The e o e, NiSn-based
ca alys s ha e he po en ial o dec ease he ca alys deac i a ion caused by coking
main aining i s high speci ic ac i i y. Sn-doped Ni ca alys s ha e been epo ed o
aqueous phase e o ming [31, 32] and me hane s eam e o ming [33] whe e he
o ma ion NixSny alloys play a key ole o inhibi coke deposi ion. Pengpanich e al.
[34] epo ed a clea example o his posi i e e ec in he pa ial oxida ion o iso-
oc ane. These au ho s ound ha he addi ion o small amoun s o in dec eased by mo e
han 50% he o ma ion o ca bon deposi s wi hou changes in he con e sion. This
enhancemen was asc ibed o he abili y o Sn o educe he g ow h o ca bon ilamen
by e a ding ca bon solubili y in he Ni pa icles [28]. Mo eo e , Saadi e al. [35] ha e
demons a ed, using densi y unc ional heo y (DFT) calcula ions, he abili y o Ni-Sn o
inhibi g aphi e o ma ion du ing s eam e o ming eac ions. They demons a ed ha he
p esence o Sn inc eases he C-C bond o ma ion ba ie .
We ha e in es iga ed p e iously he e ec o he na u e o he suppo (acidi y,
basici y and edox p ope ies) in he ca aly ic pe o mance o Sn-doped Ni ca alys s
du ing he s eam e o ming o alcohols [36-38]. The objec i e o he p esen wo k is o
in es iga e he e ec o in on he ca aly ic pe o mance o Ni-suppo ed ca alys s in
e ms o ac i i y, selec i i y and du abili y in he s eam e o ming o glyce ol.
2. Expe imen al
2.1. Ca alys s p epa a ion
The alumina suppo was ob ained by ball milling sphe ical alumina pelle s (SASOL,
1.78 mm diame e ), by using a PM4 Re sch ins umen pa icle sizes in 7 – 8 μm ange
we e achie ed. A monome allic Ni-based ca alys was p epa ed by imp egna ing he
alumina wi h an aqueous solu ion o all he ino ganic p ecu so s wi h he desi ed
concen a ions o ce ium (III) ni a e hexahyd a e (Sigma-Ald ich), magnesium ni a e
hexahyd a e (Sigma-Ald ich), and nickel (II) ni a e hexahyd a e (Sigma-Ald ich). Then,
he sample was d ied o e nigh a 100ºC and calcined a 700ºC o 12 h in lowing ai
using a hea ing a e o 10 C min-1 o ob ain 20 w .%Ni, 12 w .%CeO2, 8 w .%MgO, and
60 w .%Al2O3. The bime allic NiSn ca alys was p epa ed ollowing he same p ocedu e
bu subs i u ing a ac ion o he nickel sal by he adequa e amoun o anhyd ous in
chlo ide (Fluka) in o de o ob ain 17 w .%Ni, 3 w .%Sn, 12 w .%CeO2, 8 w .%MgO,
and 60 w .%Al2O3. The esul ing ca alys s we e labelled as Ni/CeMgAl and Ni-
Sn/CeMgAl, espec i ely.
2.2. Ma e ials cha ac e iza ion
The chemical composi ion o he samples was de e mined by X- ay luo escence
(XRF) spec oscopy in a Panaly ical AXIOS PW4400 sequen ial spec ome e wi h Rh
ube as sou ce o adia ion. The analysis we e ca ied ou on o p essed wa e s
con aining 6 w .% o wax. The ex u al p ope ies (BET su ace, po e size and po e
olume) we e s udied by ni ogen physical adso p ion-deso p ion iso he ms a 77 K
wi h Mic ome i ics ASAP 2010 equipmen . Be o e each measu emen , he samples
we e ou gassed o 2 h a 150ºC in acuum o emo e he adso bed impu i ies. X- ay
di ac ion (XRD) analysis was pe o med on a Siemens D-500 di ac ome e using Cu
Kα adia ion (40 mA, 40 kV) and a posi ion-sensi i e de ec o using a s ep size o 0.05º
and a s ep ime o 1 s. The educibili y o he ca alys s was in es iga ed by in si u XRD
analysis using a high empe a u e came a An on Paa HTK 1200 coupled wi h an X´Pe
P o Philips di ac ome e . The sys em was equipped wi h X´Cele a o de ec o wi h a
s ep o 0.05º and an equi alen ime acquisi ion o 30 s. The di ac og ams we e
eco ded in he 25 – 900ºC empe a u e ange unde a low o 100 mL min-1 (5% H2 in
A ). Su ace cha ac e iza ion was ca ied ou by X- ay pho oelec on mic oscopy (XPS)
on a Leybold-He aeus spec ome e (LHS-10/20), wo king wi h a cons an pass ene gy
o 50 eV and acuum o 5 x 10-9 To . The sys em was equipped wi h an EA-200 MCD
hemisphe ical elec on analyse wi h a dual X- ay sou ce wo king wi h Al Kα adia ion
(1486.6 eV) a 120 W and 30 mA. Binding ene gies we e e e enced o he spu ious C
(1s) signal a 284.6 eV and he a omic composi ion was es ima ed by he elemen al
sensi i i y ac o o each a om. Be o e each analysis, he sample was educed in an
ex e nal ube u nace o 1 h a 750ºC unde a o al low o 100 mL min-1 (50% H2 in
N2). Then, he sample was cooled down o oom empe a u e and placed in he
p echambe o he XPS spec ome e . The mo phology o he ca alys s was e alua ed by
SEM using a JEOL 5400 ins umen equipped wi h an Ene gy Dispe si e X- ay
Spec ome e (OXFORD LINK TETRA 1128-231).
Raman spec a we e eco ded in a dispe si e Ho i a Jobin Y on LabRam HR800
Con ocal Raman mic oscope wi h a g een lase (532.05 nm) wo king a 5 mV powe
and using a 600 g oo es/mm g a ing. The mic oscope used a 50x objec i e wi h
con ocal pinhole o 1000 μm. The Raman spec ome e was calib a ed using a silicon
wa e . The empe a u e-p og ammed oxida ion (TPO) was ca ied ou in a U-shaped
eac o unde a o al low o 50 mL min-1 (5% O2 in He) om oom empe a u e o
900ºC wi h hea ing a e o 10 ºC min-1. The o med p oduc s we e analysed by mass
spec ome y (MS) in a P ei e acuum mass spec ome e .
2.3. Ca aly ic pe o mance
The glyce ol s eam e o ming eac ion was e alua ed as a unc ion o ime o
pe iods o 4, 12 and 24 h in iso he mal condi ions a 750ºC, wi h a s eam- o-ca bon
mola a io o 4 and 100000 mL g-1 h-1 space eloci y. P io o eac ion, he samples
we e p essed, c ushed, and sie ed o achie e pa icles in he 100-200 μm ange. In each
un, 100 mg o sample was dilu ed wi h he same amoun o c ushed qua z sie ed o
he same pa icle size and placed in o he eac o be ween wo qua z wool plugs. The
ca alys s we e ac i a ed unde a o al low o 100 mL min-1 (50% H2 in N2) a 750ºC o
1 h. The expe imen s we e ca ied ou a a mosphe ic p essu e in a comme cial
Mic oac i i y Re e ence Reac o made by PiD Eng&Tech using a Has elloy C-276
ubula eac o wi h 9 mm in e nal diame e . Gas p oduc s we e analysed on-line using a
mic oGC (Va ian 4900) equipped wi h Po apak Q and Molecula Sie e – 5A columns.
A he eac o ou le a Pel ie liquid coole was i ed allowing he analysis o
condensable p oduc s by HPLC (Va ian 356-LC) equipped wi h a e ac i e index
de ec o and a Hi-Plex H column wi h milli-Q wa e as eluen .
3. Resul s and discussion
3.1. Ca alys s cha ac e iza ion

Table 1 shows he chemical composi ions and ex u al p ope ies (BET su ace, po e
size and po e olume) o he p epa ed ca alys s. Fo compa ison, he suppo was also
measu ed. The expe imen al composi ions o all samples we e close o he nominal ones
con i ming he e ec i eness o he imp egna ion me hod employed o p epa e he
ca alys s. The pa en suppo p esen s supe io BET su ace a ea, which dec eases a e
Ni o Ni-Sn addi ion caused by he inco po a ion o me al pa icles in o he po es o he
suppo .
Figu e 1 shows he XRD pa e ns eco ded o he p epa ed ca alys s. The di ac ion
peaks a 2θ = 28.8º, 33.3º, 47.7º and 56.6º can be assigned o he (111), (200), (220) and
(311) planes o he cubic luo i e phase cha ac e is ic o ce ium oxide (JCPDS 34-
0394). I can also be obse ed he di ac ion lines co esponding o he MgAl2O4 spinel
phase (JCPDS 21-1152). As desc ibed in a p e ious wo k [38] he p esence o nickel
induces he ans o ma ion o he MgAl2O4 spinel s uc u e in o a con inuous MgNi
spinel laye al hough only a pa o nickel pa ially subs i u e Mg in he MgAl2O4 phase
o ming a new NixMgyAl2O4 phase. Di ac ion peaks cha ac e is ic o nickel oxide
(JCPDS 71-1179) we e obse ed a 37º and 43º. The e o e, i can be es ablished ha a
ac ion o Ni is well dispe sed as NiO pa icles wi h mode a e in e ac ion wi h he
suppo and ano he po ion o Ni is inco po a ed wi hin he non-s oichiome ic spinel-
like phase NixMgyAl2O4 [8] wi h s ong me al-suppo in e ac ion. XRD peaks
associa ed o Sn phases we e no obse ed in he Ni-Sn/CeMgAl ca alys likely due o
i s high dispe sion.
In o de o analyse he e olu ion and he changes in he c ys alline phases p oduced
unde educ i e condi ions, in si u X- ay di ac ion analyses we e pe o med.
Reduc ion was ca ied ou in an a mosphe e o hyd ogen dilu ed in A . The ob ained X-
ay di ac og ams as a unc ion o empe a u e a e shown in Fig. 2. In bo h cases, he
s uc u al modi ica ions a e only app eciable in he high empe a u e ange (700-900
ºC). Fo he Ni/CeMgAl ca alys , he NixMgyAl2O4 and NiO phases a e educed o
me allic nickel (JDPDS 45-1027), whe eas he educ ion o he NiSn/CeMgAl ca alys
leads o he o ma ion o NixSny alloys coexis ing wi h me allic Ni pa icles. I is known
ha nickel can be comple ely alloyed wi h in o ming Ni3Sn, Ni3Sn2 and/o Ni3Sn4
in e me allic compounds depending o he Ni/Sn mola a io [39]. In ou case, he
cha ac e is ic peaks o he Ni3Sn alloy (JCPDS 35-062) we e e idenced al hough he
p esence o o he NixSny in e me allic compounds canno be uled ou . In bo h cases,
me allic nickel was also p esen a e educ ion a 700 ºC. A u he inc ease o he
empe a u e o 900 ºC led o an inc ease o he Ni di ac ion lines, which indica e a
sin e ing o he nickel pa icles.
Su ace analysis measu emen s by XPS we e pe o med o e Ni/CeMgAl and Ni-
Sn/CeMgAl ca alys s o in es iga e he chemical su ace p ope ies and oxida ion s a es
o bo h me als. P io o XPS analysis, esh ca alys s we e educed o 1 h a 750ºC
unde lowing hyd ogen dilu ed in ine o ge in o ma ion abou he chemical s a e o
he ac i a ed ca alys s. Ni 2p and Sn 3d XPS spec a a e shown in Fig. 3. Bo h
Ni/CeMgAl and Ni-Sn/CeMgAl ca alys s exhibi ed wo decon olu ed Ni2p3/2 co e-le el
peaks wi h he co esponding sa elli e peaks posi ioned o ~6 eV, espec i ely; he peak
a 856 eV can be assigned o nickel alumina e phase, while ha he peak a 853 eV was
a ibu ed o me allic nickel [40, 41]. I was obse ed ha he ela i e amoun o nickel
species inco po a ed in he non-s oichiome ic spinel-like phase NixMgyAl2O4 is simila
in bo h ca alys s while ha he ela i e quan i y o me allic nickel is sligh ly supe io in
he Ni/CeMgAl ca alys s. This obse a ion is cohe en wi h he chemical composi ion o
he ca alys s sugges ing ha he addi ional nickel in he Ni/CeMgAl ca alys is highly
dispe sed o e he suppo as nickel oxide c ys alli es. F om he XPS esul s, i is
e iden ha only he c ys alline nickel oxide was educed and he nickel wi h s ong
in e ac ion wi h he suppo equi es highe empe a u es. Bo h Ni/CeMgAl and Ni-
Sn/CeMgAl ca alys s exhibi ed iden ical amoun o nickel alumina e species s ongly
bound o he suppo which we e no educed unde ou condi ions a 750ºC. The
educ ion o Ni2+ ions inco po a ed non-s oichiome ically in e ahed al o oc ahed al
si es o spinel phases equi es empe a u es as high as 800-850 ºC [42].
The Sn 3d egion spec a o he Ni-Sn/CeMgAl ca alys is shown in Fig. 3. The peak
a 485 eV can be assigned o Sn0 species while ha he highe binding ene gy Sn 3d5/2
peak a 487 eV is a ibu able o in oxides (Sn2+ o Sn4+) [32]. The educed species o
in is p obably a Ni-Sn alloy. Disc imina ing be ween Sn2+ and Sn4+ wi h XPS is
complica ed, bu he p esence o his species indica es ha he educ ion o in was no
comple e, and oxidized species a e exis en e en a e educ ion a 750 ºC, in ag eemen
wi h p e ious esul s on alumina-suppo ed ca alys s [43]. Alumina in e ac s s ongly
wi h he in and hinde s he edu ion o SnO [44]. The e e o e, XPS analysis o he Ni-
Sn/CeMgAl a e educ ion a 750ºC indica es he p esence o Ni and Sn sepa a e
phases. The ongoing educ ion o Ni and Sn can be concu en wi h he o ma ion o a
Ni-Sn alloy, howe e his alloys a e indis inguishable by XPS om educed Ni su aces
[32]. Consequen ly, i can be p oposed ha he Ni-Sn ca alys a e ac i a ion may be
ep esen ed by he o ma ion o bime allic pa icles wi h a cen al co e o nickel
su ounded by an ou e laye ich in in (Fig. 3). Du ing he educ ion phase, a pa o Sn
a oms mig a e o he me allic nickel pa icles su ace o o m a Sn laye ha is pa ially
educed o ming a Ni-Sn alloy co e ing he su ace o Ni pa icles. As can be obse ed
in Table 2, he su ace Ni/Sn de e mined by XPS was lowe han he bulk one
sugges ing ha Sn is loca ed mainly in he su ace laye s o he ca alys . Simila
obse a ions we e ound by o he au ho s in he li e a u e [34, 45].
3.2. Ac i i y measu emen s
The ca alys pe o mances we e es ed o he hyd ogen p oduc ion in he glyce ol
s eam e o ming. Figu e 4 shows he speci ic ac i i y o bo h Ni/CeMgAl and Ni-
Sn/CeMgAl ca alys s. I is no ewo hy ha he ca aly ic beha iou was di e en in bo h
cases. The ac i i y o Ni/CeMgAl ca alys was ound o be highe han ha o he Sn-
p omo ed one and, appa en ly, e y s able o he i s 12 hou s. Once his pe iod is
eached he ca aly ic ac i i y d as ically dec eases sugges ing a as deac i a ion
p ocess. The pa ial subs i u ion o Ni by Sn in he NiSn/CeMgAl ca alys educes he
ca aly ic ac i i y bu no ably enhances he s abili y o he ca alys . As can be obse ed,
a e an ini ial s abiliza ion pe iod o he i s 4 hou s, he ca aly ic ac i i y emains
s able. The obse ed ac i i y loss upon in addi ion migh be due o he ac ha he
nickel ac i e si es o he glyce ol s eam e o ming a e co e ed by Sn species as
con i med by XPS analysis. The Sn-en iched su ace p e en s he adso p ion o he
glyce ol molecules on he me allic nickel su ace and he subsequen e o ming
eac ions. Simila obse a ions we e ea ly epo ed in he li e a u e o he
NiSn/Ce0.75Z 0.25O2 [34] and P Sn/C [46] sys ems.
The same gaseous p oduc s we e de ec ed in bo h ca alys s (H2, CO, CO2, CH4 and
C2H4, Figu e 5), al hough wi h a di e en p oduc dis ibu ion. Condensable p oduc s
such as oxygena ed compounds we e no de ec ed a his eac ion empe a u e in good
ag eemen wi h p e ious esul s [36]. Hyd ogen was he main componen in bo h
ca alys s and emained in a ian du ing all ime-on-s eam. I can be no iced ha du ing
he i s 12 hou s, he Ni/CeMgAl ca alys p oduced he maximum hyd ogen mola
ac ion possible (70%) acco ding o he s oichiome y o he eac ion (1). A e 12 h o
eac ion changes in he mola composi ion we e obse ed. F om he e, he p oduc ion o
CO2 dec eases along wi h he inc ease o CO, CH4 and C2H4. Mo eo e , he change o
selec i i y appea s when ac i i y loss is obse ed. Fo he Ni-Sn/CeMgAl ca alys , an
inc ease o CO and dec ease o CO2 s a ed om he beginning o he eac ion while
ha CH4 and C2H4 we e p oduced con inuously.
The di e ences obse ed in bo h cases would be associa ed o he ca aly ic p ocesses
in ol ed in he glyce ol decomposi ion p ocess. The o e all eac ion o glyce ol s eam
e o ming (1) may be iewed as he combina ion o he glyce ol decomposi ion (2) and
he wa e gas shi (WGS) eac ion (3). Fu he mo e, i may also be accompanied by
o he he modynamically easible eac ions ha include:
2C3H8O3 (g) + H2 (g) ↔ 3CH4 (g) + 3CO (g) + 3H2O (g) (4)
CO (g) + 3H2 (g) ↔ CH4 (g) + H2O (g) (5)
CO2 (g) + 4H2 (g) ↔ CH4 (g) + 2H2O (g) (6)
CO2 (g) + CH4 (g) ↔ 2CO (g) + 2H2 (g) (7)
C(s) + H2O (g) → CO (g) + H2 (g) (8)
C(s) + CO2 (g) ↔ 2CO (g) (9)
C(s) + 2H2 (g) ↔ CH4 (g) (10)
The ini ial gas p oduc s dis ibu ion o Ni/CeMgAl ca alys indica es ha he WGS
eac ion was p edominan in he i s 12 h. This is consis en wi h a p oduc ion o
hyd ogen close o he equilib ium alue. A e 12 h o eac ion me hane and e hylene
a e p oduced. A aque e al. [13] sugges ed ha he o ma ion o me hane p oceeds
h ough ca bon monoxide me hana ion (5) while e hylene would be o igina ed by
hyd ogena ion/dehyd a ion o ca bonyl in e media es species. Cheng e al. [47]
p oposed, howe e , ha me hane is p oduced om he hyd ogenolysis o glyce ol (4)
uling ou he me hana ion eac ion as pa h o me hane p oduc ion. The s able
p oduc ion o me hane o Ni-Sn/CeMgAl ca alys sugges s ha me hane could be
o igina ed p edominan ly om he glyce ol hyd ogena ion and he ca bon
hyd ogena ion (10). Indeed, he s eam gasi ica ion o ca bon (8) and he Boudoua d
eac ion (9) may also accoun o he inc eased s abili y o Ni-Sn ca alys educing he
deposi ion o ca bonaceous species while he p oduc ion o CO and H2 keeps cons an .
CO o ma ion on Sn is he a ou ed eac ion om CO2 decomposi ion, especially o
[25] Chiodo V, F eni S, Gal agno A, Mondello N, F us e i F. Ca aly ic ea u es o Rh
and Ni suppo ed ca alys s in he s eam e o ming o glyce ol o p oduce hyd ogen.
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TABLES AND FIGURES
Table 1. Chemical composi ion and ex u al p ope ies o he p epa ed ca alys s
w .% composi iona
a .% composi ion
SBET
(m2 g-1)
Al2O3
MgO
CeO2
Ni
Sn
Ni
Sn
Ni/Sn
CeMgAl
77.9
(78)
9.6
(10)
12.5
(12)
-
-
-
-
-
106
Ni/CeMgAl
63.6
(60)
6.6
(7)
11.1
(12)
18.7
(20)
-
27.5
-
-
89
Ni-Sn/CeMgAl
60.1
(60)
6.8
(7)
11.9
(12)
17.3
(17)
3.7
(3)
25.6
2.7
9.4
86
a Nominal alues in pa en hesis
Table 2. Su ace composi ion ob ained by XPS analysis o he educed and spen
ca alys s
a .% composi ion
a
Al
Mg
Ce
O
Ni
Sn
C
Ni/Sn
Ni/CeMgAl educed
18.7
5.1
2.0
69.5
4.6
(27.5)
-
-
Ni/CeMgAl spen
-
-
0.15
4.35
-
-
95.5
Ni-Sn/CeMgAl educed
17.8
6.1
2.0
69.2
3.7
(25.6)
1.1
(2.7)
-
3.4
(9.4)
Ni-Sn/CeMgAl spen
3.5
2.1
0.4
21.7
0.5
0.1
71.8
5.0
a Bulk alues in pa en hesis
Fig. 1 XRD pa e ns o he p epa ed ca alys s
Fig. 2 In si u XRD pa e ns in educ i e a mosphe e o he p epa ed ca alys s: (a)
Ni/CeMgAl and (b) Ni-Sn/CeMgAl

Fig. 3 XPS spec a in he Ni 2p and Sn 3d le el and pic o ial ep esen a ion o educed
ca alys
Fig. 4 Ca aly ic ac i i y as a unc ion o ime o glyce ol s eam e o ming a 750ºC o
he p epa ed ca alys s
Fig. 5 P oduc dis ibu ion in glyce ol s eam e o ming a 750ºC o he s udied
ca alys s
Fig. 6 SEM mic og aph o he esh and used ca alys s, a e 4 h and 24 h on s eam in
glyce ol s eam e o ming a 750 ºC