Catalytic acetoxylation of lactic acid to 2-acetoxypropionic acid, en route to acrylic acid

Article abstract of DOI:10.1039/c4ra12695e

We present an alternative synthetic route to acrylic acid, starting from the platform chemical lactic acid and using heterogeneous catalysis. To improve selectivity, we designed an indirect dehydration reaction that proceeds via acetoxylation of lactic acid to 2-acetoxypropionic acid. This intermediate can then be pyrolized to acrylic acid. Acetic acid is used both as a reagent and a solvent in the first step, and may be recovered in the subsequent pyrolysis step. We tested a range of solid acid catalysts for the acetoxylation step (Y zeolites, sulfated zirconia, ion-exchange resins, sulfonated graphene, and various sulfonated silica gels and mixed oxides). Recycling studies were carried out for the most active catalysts. To enable quantitative analysis using gas chromatography we also developed a reliable silylation derivatization method, which is also reported. These results open opportunities for improving the biorenewable production of acrylic acid.

Full text of DOI:10.1039/c4ra12695e

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: R. Beerthuis, M.
Granollers, D. R. Brown, H. J. Salavagione, G. Rothenberg and R. N. Shiju, RSC Adv., 2014, DOI:
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 7
RSC Advances
View Article Online
DOI: 10.1039/C4RA12695E
143x134mm (150 x 150 DPI)

RSC Advances
Page 2 of 7
View Article Online
DOI: 10.1039/C4RA12695E
RSC Advances
RSCPublishing
ARTICLE
Catalytic acetoxylation of lactic acid to 2-
acetoxypropionic acid, en route to acrylic acid
Cite this: DOI: 10.1039/x0xx00000x
Rolf Beerthuis,1 Marta Granollers,2 D. Robert Brown,2 Horacio J. Salavagione,3
Gadi Rothenberg1 and N. Raveendran Shiju*1
Received 00th xxx 2014,
Accepted 00th xxx 2014
We present an alternative synthetic route to acrylic acid, starting from the platform chemical
lactic acid and using heterogeneous catalysis. To improve selectivity, we designed an indirect
dehydration reaction that proceeds via acetoxylation of lactic acid to 2ꢀacetoxypropionic acid.
This intermediate can then be pyrolized to acrylic acid. Acetic acid is used both as a reagent
and a solvent in the first step, and may be recovered in the subsequent pyrolysis step. We
tested a range of solid acid catalysts for the acetoxylation step (Y zeolites, sulfated zirconia,
ionꢀexchange resins, sulfonated graphene, and various sulfonated silica gels and mixed
oxides). Recycling studies were carried out for the most active catalysts. To enable
quantitative analysis using gas chromatography we also developed a reliable silylation
derivatization method, which is also reported. These results open opportunities for improving
the biorenewable production of acrylic acid.
DOI: 10.1039/x0xx00000x
www.rsc.org/
1. Introduction
Biorenewable production of bulk chemicals receives much
attention in academia and industry. It is considered a must for a
sustainable society. However, most of today’s biorenewable
bulk products are based on biotechnological processes.1, 2 This
creates a barrier for the chemical industry, which, being
conservative, prefers using known and trusted chemical routes
and unit operations. This is well justified from an economic
point of view, since moving to new technologies is riskier.3
Herein, we investigate the biorenewable production of acrylic
acid starting from biosourced lactic acid (LA), yet using a
chemocatalytic route. Our results show that this gives a valid
and promising pathway for making acrylic acid from
biorenewables.
Fig. 1 Acrylic acid and its major end-products.
absorbent polymers (55%) and various acrylic esters (30%, see
Fig. 1). These are incorporated in many useful products,
including diapers and synthetic rubber. In 2012, global acrylic
acid production was 4.5 million metric tons, with a growing
demand of 4% per year.4ꢀ6 It is currently produced through a
twoꢀstep gasꢀphase oxidation of propylene via acrolein.4 This
Acrylic acid (AA) is an important bulk chemical. It is a
versatile intermediate and monomer used for making superꢀ
energy intensive process depends on petrobased propylene, the
cost of which has been volatile recently.7,
8
Several
biotechnological pathways have been proposed as alternatives,
but, none of these are currently commercially viable.9
One attractive possibility is starting from lactic acid,
because it has a C3 carbon skeleton and already contains the
external carboxyl group.10 Today, LA is produced via
1 Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam,
P.O. Box 94157, 1090GD Amsterdam, The Netherlands. E-mail:
n.r.shiju@uva.nl. Web: http://hims.uva.nl/hcsc.
2
Department of Chemical Sciences, University of Huddersfield,
Huddersfield, HD1 3DH, United Kingdom.
3
Departamento de Física de Polímeros, Elastómeros y Aplicaciones
fermentation of starch or glucose, with global production of ca
.
Energéticas, Instituto de Ciencia y Tecnología de Polímeros, CSIC,
c/Juan de la Cierva, 3, 28006 Madrid, Spain.
† Electronic Supplementary Information (ESI) available: [GCꢀMS, 1H
400 ktpa in 2012. We expect this to grow further as processes
using molasses/whey waste and lignocellulosic biomass come
on stream.11ꢀ13
NMR and GC calibration data]. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 2014
J. Name., 2014, 00, 1-7 | 1

Page 3 of 7
ARTICLE
RSC Advances
View Article Online
Journal Name
DOI: 10.1039/C4RA12695E
1
Dehydration of LA to acrylic acid was done both in the more details, including qualitative GCꢀMS and H NMR data,
liquid and vapour phase, using various sulfate14 and phosphate see the ESI.
based catalysts15, 16, inorganic salts17, 18 and various modified
Unless stated otherwise, chemicals were purchased from
Faujasite zeolites.19ꢀ21 The best results were reported by commercial sources and used as received. Acrylic acid, 2ꢀ
Ghantani et al.,22, 23 who obtained 78% yield at full conversion, acetoxypropionic acid, DLꢀlactic acid (90% aqueous solution),
converting a lactic acid feed (25 wt%) over a calcium lactide
(3,6ꢀDimethylꢀ1,4ꢀdioxaneꢀ2,5ꢀdione),
pꢀtolueneꢀ
pyrophosphate catalyst at 375 °C, with a WHSV of 3 hꢀ1.
sulfonic acid monohydrate, sulfanilic acid (99%), sodium nitrite
Generally, decarboxylation of the carbocation intermediate and hydrochloric acid were purchased from Sigma Aldrich.
results in low selectivity.4, 24, 25 One route that can overcome the Graphene powder was purchased from Angstron Materials.
problems involved with the direct dehydration of LA, is the Glucose, activated carbon, acetic acid and concentrated sulfuric
acetic acid esterification to give 2ꢀacetoxypropionic acid (2ꢀ acid (98%) were obtained from VWR International. Amberlyst
APA). Subsequent pyrolysis of 2ꢀAPA is straightforward, with 70 was purchased from Rohm and Hass. Faujasite Y zeolite in
over 95% yield.6, 26 This route was reported previously using the sodium form (nominal Si/Al ratio of 5.1) was purchased
27
homogeneous catalysis.26,
Such catalysts, however, are too from Zeolyst International. Sulfated zirconia was obtained from
expensive for largeꢀscale application. Therefore, we turned to MEL Chemicals. Silica gel 60 Å, 0.105ꢀ0.2 mm (70–150
solid catalysts, which are both cheaper and easier to separate.28
mesh), Nafion NR50, Ammonium heptamolybate, telluric acid,
vanadyl sulfate and niobium oxalate were purchased from Alfaꢀ
Aesar.
2.2. Procedure for Acid-Catalysed Acetoxylation Esterification
In a typical catalytic experiment, LA(aq) (90 wt%, 1.0 g) and a
solid acid catalyst (0.165 g, 5.5 wt% of the total weight of LA
and AcOH) were added to AcOH (2.0 g) in a threeꢀneck roundꢀ
bottom flask equipped with a reflux condenser, under vigorous
stirring at 100 °C and ambient pressure. The initial molar ratio
of LA to AcOH was 1:3.3 and no additional solvent was added.
Substrate conversion and product yield were monitored by GC.
Here, we describe the efficient solid acid catalysed
acetoxylation of LA to 2ꢀAPA. Subsequent pyrolysis can yield
AA in high efficiency, regenerating acetic acid in the process
(eqn (1)). The cyclic elimination of AcOH does not proceed via
a carbocation intermediate, increasing the selectivity to acrylic
acid. We tested a number of solid acid catalysts (Y zeolites,
sulfated zirconia, ionꢀexchange resins, sulfonated graphene, and
various sulfonated silica gels and mixed oxides) and compared
those for activity and reusability. Accordingly, the highest
activity and selectivity were found for various sulfonic based
catalysts. Of those, the ionꢀexchange resins showed the best
recycling results.
Hourly samples of 12,4
µL reaction mixture were diluted to 750
µL with dichloromethane (DCM), and reacted with 250
µL
N,Oꢀbis(trimethylsilyl)trifluoroꢀacetamide (BSTFA) silylating
reagent in a closed glass vial. These were placed in a water bath
at 44 °C for 24 h to obtain full silylation of the analytes, prior to
injection into the GC.
2.3. Procedures for Catalyst Synthesis
Most catalysts were prepared by modifying published
procedures. Nevertheless, since small changes in the synthesis
protocol can cause large effects in catalyst performance,29 we
included the detailed modified procedures in the ESI.
2. Experimental Section
2.1. Materials and Instrumentation
Gas chromatography (GC) analysis was performed on an
Agilent 7820A instrument equipped with a flame ionization
detector (FID), an autosampler (G4513A) and a 30 m × 0.32
mm i.d. VBꢀ1 fused silica capillary column, coated with
Sulfonated graphene can be prepared by in situ29 and ex
situ30 approaches. Here, we chose a twoꢀstep ex situ procedure,
preparing first the diazonium salt of sulfanilic acid and then
coupling it to graphene. Sulfanilic acid (17.4 g, 0.1 mol) was
dispersed in 1M HCl(aq) (750 mL) and maintained at 3–5 °C in
an ice bath. The diazonium salt was then formed by controlled
addition of NaNO2 (7.83 g, 0.11 mol) in aqueous solution (80
mL) for 2 h under magnetic stirring. The solid was filtered and
washed with cold water. The diazonium salt was then dispersed
in a 1:1 water/ethanol solution (360 mL) before adding
graphene (480 mg) at 3–5 °C. Then, a portion of H3PO2(aq) (50
wt%, 180 mL) was added. After 30 min stirring, another
portion of H3PO2(aq) (50 wt%, 180 mL) was added and the
solution was stirred for 1 h. The sulfonated graphene was
filtered, washed with abundant water and dried under vacuum.
dimethylpolysiloxane polymer at 3.00 µm film thickness (VICI
AG International CFSꢀA03032ꢀ300B). The carrier gas was
helium held at 77 kPa head pressure with a split ratio of 20:1.
The split/splitless injection port was held at 200 °C and the
flame ionization detector at 250 °C. For the analysis method,
the GC oven was programmed to start at 90 °C for 2 min, then
to reach 200 °C at 10 °C/min, followed by an increase in
temperature to 280 °C at a rate of 30 °C/min, followed by an
isotherm of 5 min. Under these conditions, the retention times
were 5.7 min for silylated acrylic acid (AAꢀTMS), 10.2 min for
silylated 2ꢀacetoxypropionic acid (2ꢀAPAꢀTMS), 10.5 min for
diꢀsilylated lactic acid (LAꢀTMS) and 11.2 min for lactide. For
2 | J. Name., 2014, 00, 1-7
This journal is © The Royal Society of Chemistry 2014

RSC Advances
Page 4 of 7
View ArticAle ROnTliInCeLE
Journal Name
DOI: 10.1039/C4RA12695E
2.4. Procedure for catalyst re-use.
Generally, alcohols are more readily silylated than carboxylic
acids. However, we observed a lower susceptibility towards the
silylating reagent for LA than for the other analytes. This is
caused by the intramolecular hydrogen bonding that stabilizes
the secondary hydroxyl group. Full conversion was obtained
after 24 h at 44 °C. This method enables accurate GC
calibration, with an R2 value of 0.9975 for seven observations
(for details and calibration graph see the ESI).38ꢀ40
The spent catalysts were separated by centrifugation and
decantation, and recycled by consecutive washing with acetone
(10 mL) and nꢀhexane (10 mL). After the final washing, the
catalysts were transferred in minimal volume of acetone to a
preꢀweighed 3ꢀneck roundꢀbottom flask. It was then dried under
reduced pressure at 40 °C, prior to ovenꢀdrying the catalysts at
110 °C for 1 h. Afterwards, fresh catalyst was added to reꢀ
adjust the weight to 0.165 g.
3.2. Catalyst testing and structure-activity considerations
Various solid acid catalysts were tested for activity in the
acetoxylation reaction. These catalysts are known to be active
in esterification41ꢀ45 and hydrolysis reactions,46, 47 as well as in
the production of acrylic acid from glycerol and acrolein.48
Accordingly, we screened zeolites, commercial ionꢀexchange
resins, (mixed) metalꢀoxides, and sulfonated carbonaceous and
siliceous catalysts. All catalysts were tested using an initial
LA:AcOH molar ratio of 1:3.3, at 100 °C under atmospheric
pressure. Hourly samples were taken to determine LA
conversion and 2ꢀAPA yield (Fig. 2).
A blank experiment in the absence of any catalyst, showed
<5% 2ꢀAPA yield after 5 h. Similarly, a homogeneous control
experiment using concentrated H2SO4 showed stabilization at
chemical equilibrium at around 51% yield. In the batch
reaction, water is not removed and limits higher yields. H2SO4
was used in 0.5 H+ equivalents (22.65 mg), equal to the ionꢀ
exchange capacity of Amberlyst 70 at 5.5 wt%.
3. Results and Discussion
3.1. Analytical Method Development
Analysing hydroxy carboxylic acids by HPLC and GC is
difficult.30ꢀ35 On various commonlyꢀused columns, the direct
analysis of LA by HPLC and GC gives broad and erratic
responses, due to strong interactions with the stationary phases.
Furthermore, analysing the reaction mixture using 1H NMR
spectroscopy showed additional overlapping signals. LA is
known to contain oligomers as a result of selfꢀcondensation.36
Moreover, oligomerization of LA is likely to occur at 100 °C in
the presence of an acid catalyst. These oligomers give NMR
signals of chemical shifts similar to LA and 2ꢀAPA.37 Thus, we
1
could not use H NMR spectroscopy for accurate analysis of
LA, 2ꢀAPA and AA.
Addressing these issues, we developed a simple and reliable
analytical method, which is suitable for use on simple silicaꢀ
based capillary columns. The method is based on silylation
using N,Oꢀbis(trimethylsilyl)trifluoroacetamide (BSTFA).
Next, we evaluated the activity of Faujasite Y zeolites. We
synthesized both microporous and macroporous Y zeolites, but
Fig. 2 Time-resolved yield of 2-APA, for various acid catalysts (colored lines are used to guide the eye; the dotted vertical line at t=3h denotes the point of comparison
between the catalysts for comparing performance). Reaction conditions: LA to AcOH ratio 1:3.3, catalyst 5.5 wt% of total LA and AcOH amount, T = 100 °C.
This journal is © The Royal Society of Chemistry 2014
J. Name., 2014, 00, 1-7 | 3

Page 5 of 7
ARTICLE
RSC Advances
View Article Online
Journal Name
DOI: 10.1039/C4RA12695E
these gave very low 2ꢀAPA yields. Though the zeolites have four were almost equivalent (see dotted vertical line in Fig. 2).
high acidic strength, it seems that the reaction is limited by the The 2ꢀAPA yields at this point varied between 34–37% and
restricted pore size.
selectivity to 2ꢀAPA ranged from 83–90% (Table 1). These
We then turned to commercial ionꢀexchange resins, known results were obtained under standard reaction conditions,
for high activity in acid catalysed reactions, and thermal and without further optimization. As such, optimization of the
mechanical stability. These were Amberlyst 70 (macroporous reaction conditions is expected to surpass 90% selectivity.
sulfuric acid functionalized styrene divinylbenzene copolymer) Combining these results with the pyrolysis of 2ꢀAPA at
and Nafion NR50 (mesoporous sulfonated tetrafluoroethylene elevated temperatures,6, 26 we envisage 80–85 % overall acrylic
based fluoropolymerꢀcopolymer beads). Both catalysts showed acid yield in the continuous flow reaction.
high activity and selectivity to 2ꢀAPA.
Sulfated zirconia (SZ) was previously demonstrated as an
active acid catalyst, with thermal stability and strong acid
sites.42, 45 Two SZ catalysts were prepared by calcination at 450
°C and 650 °C, but both showed low activity. The mixed phase
Mo–V–Te–Nb–O catalyst, known for the conversion of
glycerol to acrolein and AA,48 showed only moderate activity.
Control experiments using pure tellurium oxide or niobium
oxide, known to be active in similar conversions, showed low
activity.49, 50 Moreover, when testing single phase Mo–V–Te–
Nb–O materials,51 reduced activity was observed. This suggests
that the active acid sites form part of the mixed phase catalyst.
Sulfonated graphene showed high activity and selectivity to
2ꢀAPA. However, additional AcOH (ca. 12 mL) was required
to facilitate mixing, as graphene tends to absorb polar solvents.
Control experiments using the same additional amount of
AcOH with Amberlyst 70 as the catalyst showed only minor
Fig. 3. NH3 adsorption microcalorimetry results for various samples. The acid
strength is proportional to the heat of adsorption, and the surface coverage
indicates the concentration of acid sites.
change in the reaction profile compared to the reaction under
NH3 adsorption microcalorimetry was measured on the
typical conditions. We can thus compare directly the results for
samples after activation at 100 °C for 2h (Fig. 3). The results
sulfonated graphene with those for the other catalysts. Sulfonic
show that Amberlyst 70 (Aꢀ70) has a few stronger acid sites
acid functionalized silica gel gave only modest activity.
than the rest of the catalysts. The highest acid strength is similar
Moderate results were also obtained using
pꢀtoluenesulfonic
for sulfonated graphene, ACꢀSO3H and Nafion NR50.
However, sulfonated graphene has the highest concentration of
strong acid sites (i.e., sites with –ꢁHads< 80 kJ mol–1). The
surface coverage values with an adsorption threshold of 80 kJ
mol–1 were 1.22, 0.52, 0.11, 0.91, 0.90 mmol gꢀ1 for sulfonated
graphene, ACꢀSO3H, Nafion NRꢀ50, HY meso and Amberlyst
70, respectively. Other samples showed weaker acidities.
Turnover frequencies (TOFs) were calculated by taking moles
of product, divided by moles of acid sites (from
microcalorimetry) over time (Table 1).
acid functionalized glucose (GluꢀTsOH). Conversely, sulfonic
acid functionalized activated carbon (ACꢀSO3H) showed high
activity and selectivity.
Though esterification is promoted by both Lewis and
Brønsted acids, we think the latter plays a more important role
here. Since we deliberately put –SO3H groups on carbon, their
concentration is high and at a relatively low temperature of 100
°
C, they are likely to have more influence than Lewis acid
sites.52
Table 1 Conversion (X), selectivity (S), yield (Y) and turnover frequency
(TOF) for acetoxylation of LA to 2ꢀAPA, for the four most active catalysts.
3.3. Mechanistic Studies
Generally, esterification is promoted by both Lewis and
Brønsted acids, following the Fischer esterification
mechanism.53 In the acetoxylation reaction, we observed that
increasing the amount of AcOH in the initial reaction mixture
leads to lower conversion and higher selectivity. Accordingly,
the reaction conditions were maintained uniform throughout
(LA:AcOH ratio 1:3.3; 100 °C), to compare catalytic activities
of the various catalysts.
The influence of LA oligomerization was studied by an
induction experiment (Fig. 4, empty circles), where we first ran
the reaction with no catalyst for 5 h, and then added Amberlyst
70. This gave higher 2ꢀAPA yields (cf. the standard conditions,
Fig. 4, full circles), suggesting that the induction period
XLA (%) S2ꢀAPA (%) Y2ꢀAPA (%) TOF (hꢀ1)
Amberlyst 70
Nafion NR50
42
41
44
42
87
90
84
83
37
37
37
34
8
70
15
6
ACꢀSO3H
Sulfonated graphenea
Reaction conditions: LA to AcOH ratio 1:3.3, catalyst 5.5 wt% of total LA
and AcOH amount, T = 100 °C. Samples taken after 3 h. a Additional AcOH
was required to obtain a mixable slurry.
The four most active catalysts were Amberlyst 70, Nafion
NR50, ACꢀSO3H and sulfonated graphene. These catalysts all
contain sulfonic functional groups. After 3h, the yields for all
This journal is © The Royal Society of Chemistry 2014
J. Name., 2014, 00, 1-7 | 4

RSC Advances
Page 6 of 7
View ArticAle ROnTliInCeLE
Journal Name
DOI: 10.1039/C4RA12695E
promotes LA conversion to oligomers, which are more reactive. by fouling or collapse of the support. The second is leaching of
In the industrial synthesis of polylactic acid, LA is first the acid groups, resulting in permanent loss of the catalytic
converted to lactide, which is more active in ringꢀopening activity. In fact, for graphene it was demonstrated that strong
polymerization.54, 55 This a twoꢀstep process – the LA is first
condensed by removing water above 200 °C. Then, the dimer is
cyclized, either thermally, or in the presence of an acid catalyst.
However, when we used lactide as the substrate for
comparison, we saw lower yields of 2ꢀAPA (Fig. 4, square
symbols).
Fig. 5 Yield of 2-APA over multiple recycling steps. Samples taken after 3 h (cf.
dotted vertical line in Fig 2). Reaction conditions: LA:AcOH ratio 1.0:3.3; catalyst
5.5 wt% (w.r.t. the total amount of LA and AcOH); 100 °C.
absorption of chemicals occurs in parallel with the covalent
diazotization, even using long washing procedures.53
Elemental analysis of the fresh and spent Amberlyst 70
samples shows 99% retention of sulfonic groups. This explains
the maintained activity during recycling. Conversely, the spent
Fig. 4 Time-resolved yield of 2-APA. Reaction conditions: LA/lactide to AcOH ratio
1:3.3, 5.5 wt% (w.r.t. the total amount of LA and AcOH) Amberlyst 70, T = 100 °C.
sulfonated graphene catalyst lost 50% of its sulfur. It is difficult
to say the reason, however, it was observed previously that
Negative time denotes the induction period in absence of any catalyst, before
introducing Amberlyst 70 at t=0.
reaction and treatment conditions influence the recyclability of
the resin catalysts.57 Also, the leaching of –SO3H groups is
3.4. Catalyst Recycling Studies
reaction specific. For example, we observed leaching from
We then carried out recycling studies for the four most active
sulfonated silica in hemicellulose depolymerisation,47 while
solid acid catalysts. The influence of different washing solvents
there was no leaching from the same type of catalyst in
for catalyst regeneration was tested using H2O, ethanol,
conversion of furfuryl alcohol into butyl levulinate.58
acetone, toluene and nꢀhexane. For the carbonaceous catalysts,
washing only with polar solvents caused a dramatic loss of
activity, while nonꢀpolar solvents gave only a slight decrease.56
For the ionꢀexchange resins, varying the washing solvent did
not influence the catalytic activity. Polar solvents can remove
organic deposits, as well as weakly bonded acid groups. Nonꢀ
polar solvents may remove carbonaceous residues. Optimal
4. Conclusions
The solidꢀcatalysed acetoxylation of lactic acid is a selective
route to 2ꢀacetoxypropionic acid. Subsequent pyrolysis can give
acrylic acid, whilst simultaneously regenerating acetic acid,
which is also the solvent in the first step. Yields of up to 85%
acrylic acid are expected when both steps are combined.
Various sulfonated ionꢀexchange resins and carbonꢀbased
catalysts show high activity and selectivity, in reacting a 90
wt% lactic acid solution. The recycling studies demonstrate that
the carbonꢀbased catalysts lose their activity due to leaching of
the sulfonic groups, while, the activity of the ionꢀexchange
resins stabilizes after several runs. These resins are good
acetoxylation catalysts, and make this synthetic route a viable
option for biorenewable production of acrylic acid.
recycling results were obtained with subsequent acetone and
hexane washing and consecutive drying.
nꢀ
After regeneration each catalyst, fresh catalyst was added to
maintain the standard weight. The activity of the recycled
catalysts was reꢀcalculated, accounting for the amount of fresh
catalyst added per cycle. Fig. 5 shows the results after reacting
3 h (note that these trends were also observed after 1 h). The
sulfonated graphene and ACꢀSO3H catalysts were less active
after each recycling step. The activity of the Nafion NR50
catalyst decreased after the first and second recycling steps, but
stabilized in further recycling. The Amberlyst 70 catalyst was
stable and remarkably showed slightly increased 2ꢀAPA yield.
This may be due to a more open polymer structure as a result of
resin swelling during the washing procedure.
References
1. T. Willke and K. D. Vorlop, Appl. Microbiol. Biot., 2004, 66, 131ꢀ
142.
2. F. Budde, U.ꢀH. Felcht and H. Frankemölle, Value Creation, Wileyꢀ
We envisage two general pathways for the deactivation of
these sulfonic catalysts. The first is blocking of the active sites,
VCH, Weinheim, 2005.
This journal is © The Royal Society of Chemistry 2014
J. Name., 2014, 00, 1-7 | 5

Page 7 of 7
ARTICLE
RSC Advances
View Article Online
Journal Name
DOI: 10.1039/C4RA12695E
3. Z. Strassberger, S. Tanase and G. Rothenberg, RSC Adv., 2014,
4
,
32. K. R. Kim, M. K. Hahn, A. Zlatkis, E. C. Horning and B. S.
25310ꢀ25318.
Middleditch, J. Chromatogr. A, 1989, 468, 289ꢀ301.
4. K. Weissermel and H.ꢀJ. Arpe, Industrial Organic Chemistry, Wileyꢀ 33. P. G. Brotz and D. M. Schaefer, J. Microbiol. Meth., 1987,
VCH, Weinheim, 2003. 144.
5. I. Chemicals, Acrylic Acid, Acrylate Esters and Superabsorbent 34. D. L. Schooley, F. M. Kubiak and J. V. Evans, J.Chromatogr. Sci.
6, 139ꢀ
,
Polymers,
1985, 23, 385ꢀ390.
http://www.ihs.com/products/chemical/planning/ceh/acrylicꢀacidꢀ
acrylateꢀesters.aspx, Accessed 04ꢀ04ꢀ2014.
35. P. S. Nassos, J. E. Schade, A. D. King and A. E. Stafford, J. Food
Sci., 1984, 49, 671ꢀ674.
6. H. A. Wittcoff, B. G. Reuben and J. S. Plotkin, Industrial Organic 36. D. T. Vu, A. K. Kolah, N. S. Asthana, L. Peereboom, C. T. Lira and
Chemicals, WileyꢀVCH, Weinheim, 2012. D. J. Miller, Fluid Phase Equilibr., 2005, 236, 125ꢀ135.
7. Platts, Global Propylene Price Index, http://www.platts.com/newsꢀ 37. S. Konishi, T. Yokoi, B. Ochiai and T. Endo, Polym. Bull., 2009, 64
feature/2014/petrochemicals/pgpi/propylene, Accessed 04ꢀ04ꢀ2014. 435ꢀ443.
8. ICIS, European propylene, butadiene, prices rise above ethylene. 38. K. Y. Tserng, C. A. Gilfillan and S. C. Kalhan, Anal. Chem., 1984,
,
2010,
http://www.icis.com/blogs/chemicalsꢀandꢀtheꢀ
56, 517ꢀ523.
economy/2010/03/europeanꢀpropyleneꢀandꢀbutadieneꢀpricesꢀriseꢀ
aboveꢀethylene/, Accessed 28ꢀ08ꢀ2013.
39. F. Khabbaz, S. Karlsson and A.ꢀC. Albertsson, J. Appl. Polym. Sci.
2000, 78, 2369ꢀ2378.
,
9. A. J. Straathof, S. Sie, T. Franco and L. M. Wielen, Appl. Microbiol. 40. A. Kamal, J. Microbiol. Biotechn., 2011, 21, 37ꢀ42.
Biot., 2005, 67, 727ꢀ734.
41. B. Zhang, J. Ren, X. Liu, Y. Guo, Y. Guo, G. Lu and Y. Wang,
10. M. Dusselier, P. Van Wouwe, A. Dewaele, E. Makshina and B. F.
Catal. Commun., 2010, 11, 629ꢀ632.
Sels, Energ. Environ. Sci. , 2013,
6
, 1415.
42. A. A. Kiss, A. C. Dimian and G. Rothenberg, Adv. Synth. Catal.
2006, 348, 75ꢀ81.
,
11. Y.ꢀJ. Wee, J.ꢀn. Kim and H.ꢀw. Ryu, Food Technol. Biotechnol.
2006, 44, 163ꢀ172.
,
43. D. Kusdiana and S. Saka, Bioresource Technol., 2004, 91, 289ꢀ295.
12. E. V. RamosꢀFernandez, N. J. Geels, N. R. Shiju and G. Rothenberg, 44. K. Komers, J. Machek and R. Stloukal, Eur. J. Lipid. Sci. Tech.
Green Chem., 2014, 16, 3358ꢀ3363. 2001, 103, 359ꢀ362.
13. F. A. Castillo Martinez, E. M. Balciunas, J. M. Salgado, J. M. 45. K. Saravanan, B. Tyagi and H. C. Bajaj, Catal. Sci. Technol., 2012,
,
,
2
Domínguez González, A. Converti and R. P. D. S. Oliveira, Trends
Food Sci. Tech., 2013, 30, 70ꢀ83.
2512.
46. J. Ji, G. Zhang, H. Chen, S. Wang, G. Zhang, F. Zhang and X. Fan,
Chem. Sci., 2011, , 484.
47. P. Demma Cara, M. Pagliaro, A. Elmekawy, D. R. Brown, P.
Verschuren, N. R. Shiju and G. Rothenberg, Catal. Sci. Technol.
2013, , 2057ꢀ2061.
14. J. Zhang, J. Lin and P. Cen, Can. J. Chem. Eng., 2008, 86, 1047ꢀ
1053.
2
15. US Pat., 1988/4729978, 1988.
,
16. US Pat., 1988/4786756, 1988.
3
17. C. T. Lira and M. P. J., Ind. Eng. Chem. Res., 1993, 32, 2608ꢀ2613.
18. US Pat., 1958/2859240, 1958.
48. J. Deleplanque, J.ꢀL. Dubois, J.ꢀF. Devaux and W. Ueda, Catal.
Today, 2010, 157, 351ꢀ358.
19. P. Sun, D. Yu, K. Fu, M. Gu, Y. Wang, H. Huang and H. Ying, 49. W. D. Pyrz, D. A. Blom, N. R. Shiju, V. V. Guliants, T. Vogt and D.
Catal. Commun., 2009, 10, 1345ꢀ1349. J. Buttrey, Catal. Today, 2009, 142, 320ꢀ328.
20. H. Wang, D. Yu, P. Sun, J. Yan, Y. Wang and H. Huang, Catal. 50. N. R. Shiju, D. R. Brown, K. Wilson and G. Rothenberg, Top. Catal.
,
Commun., 2008,
21. J. Zhang, Y. Zhao, M. Pan, X. Feng, W. Ji and C.ꢀT. Au, ACS Catal.
2011, , 32ꢀ41.
9
, 1799ꢀ1803.
2010, 53, 1217ꢀ1223.
,
51. N. Watanabe and W. Ueda, Ind. Eng. Chem. Res., 2006, 45, 607ꢀ614.
1
52. K. Wilson, D. J. Adams, G. Rothenberg and J. H. Clark, J. Mol.
Catal. A: Chem., 2000, 159, 309ꢀ314.
22. V. C. Ghantani, S. T. Lomate, M. K. Dongare and S. B. Umbarkar,
Green Chem., 2013, 15, 1211.
53. E. Fischer and A. Speier, Ber. Dtsch. Chem. Ges., 1895, 28, 3252ꢀ
3258.
23. V. C. Ghantani, M. K. Dongare and S. B. Umbarkar, RSC Adv., 2014,
4, 33319ꢀ33326.
54. D. Garlotta, J. Polym. Environ., 2001, 9, 63ꢀ84.
24. T. M. Aida, A. Ikarashi, Y. Saito, M. Watanabe, R. L. Smith and K. 55. R. Mehta, V. Kumar, H. Bhunia and S. N. Upadhyay, J. Macromol.
Arai, J. Supercrit. Fluids. , 2009, 50, 257ꢀ264.
25. W. S. L. Mok, M. J. Antal and M. Jones, J. Org. Chem. , 1989, 54
4596ꢀ4602.
Sci., Polym. Rev. , 2005, 45, 325ꢀ349.
,
56. A. Goifman, J. Gun, V. Gitis, A. Kamyshny Jr, O. Lev, J. Donner, H.
Bornick and E. Worch, Applied Catalysis B: Environ., 2004, 54, 225ꢀ
235.
26. WO 2013/036389, 2013.
27. US Pat., 2006/6992209, 2006.
57. E. Andrijanto, E. A. Dawson and D. R. Brown, Appl. Catal. B-
Environ., 2012, 115–116, 261ꢀ268.
28. E.ꢀJ. Ras, S. Maisuls, P. Haesakkers, G.ꢀJ. Gruter and G. Rothenberg,
Adv. Synth. Catal., 2009, 351, 3175ꢀ3185.
58. P. Demma Cara, R. Ciriminna, N. R. Shiju, G. Rothenberg and M.
29. E.ꢀJ. Ras and G. Rothenberg, RSC Adv., 2014,
4, 5963ꢀ5974.
Pagliaro, ChemSusChem, 2014, 7, 835ꢀ840.
30. K. Molever, J. Cosmet. Sci., 2002, 53, 121ꢀ126.
31. M. Staniforth, M. O'Hanlon and T. M. Khong, J. Chromatogr. A
1999, 833, 195ꢀ208.
,
6 | J. Name., 2014, 00, 1-7
This journal is © The Royal Society of Chemistry 2014