Noble metal-free catalytic decarboxylation of oleic acid to n-heptadecane on nickel-based metal-organic frameworks (MOFs)

Article abstract of DOI:10.1039/c7cy00564d

Nickel based metal organic frameworks (Ni-MOFs) were successfully synthesized using new conjugated carboxylic acid linkers. These conjugated carboxylic acid linkers were synthesized using mild Heck coupling that led to the incorporation of functional groups not possible by traditional synthetic methods. Control of linker size allows for porosity tuning of the crystalline network and high surface area, that, in theory, results in the increased accessibility to Ni metal centers for catalysis. The resultant crystalline Ni-MOFs displayed BET areas as high as ～314 m² g^-1. To investigate their catalytic activity for conversion of oleic acid to liquid hydrocarbons, Ni-MOFs were grown on zeolite 5A beads that served as catalytic supports. The resultant catalysts displayed heptadecane selectivity as high as ～77% at mild reaction conditions, one of the highest yields for non-noble metal containing catalysts. The catalytic activity correlated to the concentration of acid sites. A slight decrease in catalytic activity was observed after catalysts recycling.

Full text of DOI:10.1039/c7cy00564d

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ISSN 2044-4753
PAPER
Qingzhu Zhang et al.
Catalytic mechanism of C–F bond cleavage: insights from QM/MM
analysis of fluoroacetate dehalogenase
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Noble metal-free catalytic decarboxylation of oleic acid to n-
heptadecane on nickel-based metal-organic frameworks (MOFs)
L. Yang,a† B. W. McNichols,b† M. Davidson,c B. Schweitzer,a D. A. Gómez-Gualdrón,a B. G. Trewyn,bc
A. Sellinger*bc and M. A. Carreon*ac
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Nickel based metal organic frameworks (Ni-MOFs) were successfully synthesized using new conjugated carboxylic acid
linkers. These conjugated carboxylic acid linkers were synthesized using mild Heck coupling that led to the incorporation of
functional groups not possible by traditional synthetic methods. Control of linker size allows for porosity tuning of the
crystalline network and high surface area, that, in theory, results in the increased accessibility to Ni metal centers for
catalysis. The resultant crystalline Ni-MOFs displayed BET surface areas as high as ∼314 m2/g. To investigate their catalytic
activity for conversion of oleic acid to liquid hydrocarbons, Ni-MOFs were grown on zeolite 5A beads that served as
catalytic supports. The resultant catalysts displayed heptadecane yields as high as ∼77% at mild reaction conditions, one of
the highest yields for non-noble metal containing catalysts. The catalytic activity correlated to the concentration of acid
www.rsc.org/
sites.
A
slight
decrease
in
catalytic
activity
was
observed
after
catalysts
recycling.
performance in comparison to supported, noble metal
catalysts. Another drawback of non-noble bimetallic sulfide
catalysts is the sulfide contamination of resultant products.
Therefore, it is important to design effective non-noble metal
catalysts that display enhanced catalytic conversion of lipid-
based biomass into clean alternative fuel hydrocarbon
feedstock. This could be potentially achieved using metal
organic frameworks (MOFs), that have emerged as a promising
type of highly-tunable (chemically and topologically)13
crystalline microporous material. MOFs combine desirable
properties that make them ideal candidates for catalytic
applications,14 such as uniform microporosity, high surface
area,15 and (increasingly so) high thermal and chemical
stability.16,17 In principle, the metal cations or metal-based-
clusters can act as the catalytic active species, and the ordered
microporous structure can provide the pathway for guest and
product molecules to diffuse with enhanced mass transfer.18-20
Introduction
Low-cost, readily available lipid-based biomass is an attractive
feedstock for catalytic conversion into renewable alternative
fuels. Recent research efforts have focused on converting
triglycerides and fatty acids into linear, paraffinic
hydrocarbons that can be potentially used as precursors for
the production of liquid fuels, lubricants and/or other valuable
petrochemicals.1-6 Decarboxylation is an effective route for the
conversion of carboxylic acids to linear, paraffinic
hydrocarbons. Compared to biodiesel, alternative liquid fuels
produced by catalytic decarboxylation are higher quality and
more stable due to lower content or absence of oxygen.
Decarboxylation of carboxylic acids over various catalysts have
received considerable attention. However, since many of the
catalysts employ noble metals (Pd, Pt, Rh, Ru, Ir, Os) as the
active species to attain good catalytic performance, industrial
application is currently far from feasible due to limitations in
cost and scale-up.7-9 Few reports exist on non-noble metal
catalysts such as nickel bimetallic sulfide phases and other
metal oxides.10-12 Non-noble metal catalysts are significantly
lower cost, but have so far displayed limited catalytic
Herein, we report the synthesis of nickel based metal organic
frameworks (Ni-MOFs) and their improved catalytic activity (as
compared to Pd and Pt) for the decarboxylation reaction of
fatty acids. The synthesized materials include previously non-
synthesized MOFs employing novel carboxylic acid linkers.
Nickel was chosen as the inorganic metal cation due to its
promising catalytic activity for deoxygenation of fatty acids,7
and its low cost (compared to Pd and Pt, the price of Ni is
roughly 2,500X lower), that makes it appealing for
decarboxylation and/or deoxygenation reactions. Supported
nickel catalysts can afford reasonable yields of hydrocarbons in
the catalytic deoxygenation of fatty acids even in the absence
of hydrogen.21,22 Our conjugated carboxylic acid linkers allow
for new MOF structures to be prepared and tested for catalytic
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BM 65 precursor (methyl (E)-4-(3-methoxy-3-oxoprop-1-en-1-yl)
benzoate). Utilizing methyl 4-bromobenzoate (Matrix Scientific
<95%) as the aromatic halide, the procedure followed the
general synthesis described above, but using instead 1.1
equivalents of methyl acrylate, resulting in a white powder
(92% yield) 1H NMR (500 MHz, DMSO-d6) δ 7.93 (s, 2H), 7.84 (s,
2H), 7.68 (d, J = 16.0 Hz, 1H), 6.75 (d, J = 16.0 Hz, 1H), 3.82 (s,
3H), 3.70 (s, 3H).
activity. These Ni-based MOFs were grown on the surface of
zeolite 5A beads to form Ni-MOF membrane/zeolite5A bead
phases, which were then used as catalysts to convert oleic acid
to liquid hydrocarbons.
Experimental methods
All chemicals were used as received without further
purification unless noted. Dichloromethane (DCM, ACS),
anhydrous tetrahydrofuran (THF, ≥99.9%), methyl acrylate
(>99%), N,N-dicyclohexylmethylamine (NCy2Me, 97%) and
anhydrous magnesium sulfate (MgSO4), were obtained from
Sigma-Aldrich. Sodium hydroxide (NaOH, Pearl 97%) was
BM 65 ((E)-4-(2-carboxyvinyl) benzoic acid). The synthesis
followed the general hydrolysis procedure described above,
resulting in a white powder (96% yield) 1H NMR (500 MHz,
DMSO-d6) δ 12.83 (s, 2H), 7.91 (d, J = 7.6 Hz, 2H), 7.77 (d, J =
7.8 Hz, 2H), 7.60 (d, J = 16.1 Hz, 1H), 6.61 (d, J = 16.2 Hz, 1H).
13C NMR (126 MHz, DMSO-D6) δ 167.83, 167.35, 143.17,
138.88, 132.34, 130.25, 128.82, 122.11
obtained
from
Fisher
Scientific.
Bis(tri-tert-
butylphosphine)palladium (Pd[P(t-Bu)3]2, 98%) was obtained
from Strem Chemicals. Hydrochloric acid (HCl, ACS) was
obtained from Macron Fine Chemicals. All glassware was base,
acid, and water washed then oven-dried. 1H and 13C NMR
spectra were obtained on a JEOL ECA 500 liquid-state NMR
spectrometer and data obtained was manipulated in
MestReNova NMR processor software.
O
O
O
Pd(P(tBu)3)2
NCy2Me
THF
O
Br
+
O
O
O
O
70C
overnight
92% yield
methyl (E)-3-(3-methoxy-3-oxoprop-1-en-1-yl)benzoate
Carboxylic linkers synthesis and characterization
O
O
1. KOH
MeOH
Reflux
O
O
General carboxylic acid synthesis. A Schlenk flask under argon
O
O
HO
OH
and equipped with a magnetic stir bar was charged with the
2. H2O
HCl
aromatic
halide,
methyl
acrylate,
N,N-
95% yield
(E)-3-(2-carboxyvinyl)benzoic acid
dicyclohexylmethylamine, Pd[P(t-Bu)3]2 (catalyst used at 1 mol
% level), and THF. The mixture was heated to 70°C for 24 h and
periodically tested via TLC for reaction completion. The crude
product mixture was extracted three times with DCM and
acidic water (5% HCl). The organic layer was dried with MgSO4,
filtered, and the solvent removed using a rotary evaporator.
The resultant crude product was then further purified by flash
chromatography and excess was solvent removed using a
rotary evaporator. The ester precursor was then converted to
the corresponding acid by refluxing for 4 h in a NaOH (x10 mol
equivalents) and methanol solution followed by cooling,
acidification to >2 pH with HCl, then the pure acid product was
collected by vacuum filtration.
Scheme 2. Heck coupling and subsequent ester hydrolysis
leading to the diacid BM 73.
BM 73 precursor (methyl (E)-3-(3-methoxy-3-oxoprop-1-en-1-yl)
benzoate). Utilizing methyl 3-bromobenzoate (Sigma-Aldrich
98%) as the aromatic halide, followed the general synthesis
above with the only change of 1.1 equivalents of methyl
1
acrylate was utilized resulting in a white solid. (92% yield) H
NMR (500 MHz, DMSO-d6) δ 8.16 (s, 1H), 7.95 (dd, J = 21.6, 7.8
Hz, 2H), 7.69 (d, J = 16.1 Hz, 1H), 7.53 (t, J = 7.8 Hz, 1H), 6.67
(d, J = 16.1 Hz, 1H), 3.83 (s, 3H), 3.69 (s, 3H). 13C NMR (126
MHz, DMSO-D6) δ 166.96, 166.30, 143.87, 135.14, 132.98,
131.28, 130.91, 129.94, 129.57, 119.76, 52.82, 52.10, 40.04.
O
Pd(P(tBu)3)2
BM 73 ((E)-3-(2-carboxyvinyl) benzoic acid). The synthesis
followed the general hydrolysis procedure described above
resulting in a white powder. (95% yield) 1H NMR (500 MHz,
DMSO-d6) δ 8.12 (s, 1H), 7.93 (d, J = 4.6 Hz, 2H), 7.62 (d, J =
NCy2Me
THF
Br
O
O
+
O
O
70C
overnight
O
O
92% yield
O
methyl (E)-4-(3-methoxy-3-oxoprop-1-en-1-yl)benzoate 15.5 Hz, 1H), 7.51 (d, J = 10.8 Hz, 1H), 6.55 (d, J = 15.6 Hz, 1H).
13C NMR (126 MHz, DMSO-D6) δ 167.88, 167.42, 143.45,
OH
O
1.MeOH
NaOH
Reflux
135.20, 132.52, 132.06, 131.28, 129.80, 129.52, 120.97, 40.02.
O
O
O
O
Figures S1-S6 show the NMR spectra (1H, 13C)] for BM65 and
BM73 and ester precursors.
2. H2O
HCl
96% yield
OH
O
(E)-4-(2-carboxyvinyl)benzoic acid
Scheme 1. Heck coupling and subsequent ester hydrolysis
Ni-MOF synthesis and characterization
leading to the diacid BM 65.
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All Ni-MOF crystals were prepared via
a solvothermal carbon dioxide, which is the gas atmosphere employed during
approach.23 The employed inorganic source was nickel nitrate the decarboxylation reactions.
hexahydrate (Alfa Aesar, ≥97%) and the employed organic
linkers were BM 65 and BM 73, and, for comparison, the Reaction procedures
conventional BTC linker, benzene-1,3,5-tricarboxylic acid. The
Oleic acid (90%, Alfa Aesar) was used as the model fatty acid
molecule. Before the reaction, the catalysts were pre-activated
in an oven for 3 h at 150 °C. The reactions were conducted in a
100 mL stainless steel, high pressure batch reactor (Parr model
4560). Oleic acid and the catalyst were loaded into the reactor
(mass ratio 1:1). Before the reaction was initiated, the air in
the reactor was removed by flowing CO2, followed by a
pressure increase to 20 bar. Then the reactor was heated to
340 °C under constant stirring, and the temperature was kept
constant during the duration of the reaction. After the
reaction, the catalyst was separated from the product and
washed with n-hexane 3 times, then with methanol 3 times,
and finally heated at 300 °C overnight to remove the
carbonaceous species formed during reaction.
molar ratio of the nickel source to organic linker was kept
constant at 4.08:1. In a typical synthesis, 2.0 g of nickel nitrate
hexahydrate was dissolved in 15 mL of deionized water. In a
separate beaker, 0.3 g of linker was dissolved in a solution
mixture of 7.5 mL deionized water and 7.5 mL ethanol. The
two solutions were combined and the resultant mixture was
stirred thoroughly for 2 h. The mixture was transferred into a
45 mL Teflon-lined stainless steel autoclave and heated at 180
°C for 24 h. Then, the autoclave was cooled down to room
temperature, and the resultant crystals at the bottom of the
autoclave were washed with methanol three times. The
crystals were dried overnight in the oven at 80 °C and used for
subsequent characterization.
Ni-MOF/5A bead catalyst synthesis and characterization
Product analysis
Ni-MOF/zeolite 5A bead catalysts were prepared by
solvothermally growing Ni-MOF on zeolite 5A beads (Grace
Company) as described in our recent studies.24,25 This zeolite
displays LTA topology and has uniform micropores of ~0.5 nm.
A similar Ni/organic linker mixture as described above was
used and transferred into a 45 mL Teflon-lined stainless steel
autoclave containing 5 g of pure zeolite 5A. The autoclave was
then heated at 180 °C for 24 h. The resultant layered 5A beads
were dried overnight at 80 °C. A second layer of Ni-MOF was
applied repeating the procedure described above.
The liquid product was collected and analyzed with a gas
chromatograph (GC, 6980N) equipped with a HP-5 MS column
(with dimensions of 30 m × 250 µm × 0.25 µm) and a 5973N
MSD detector. Before the GC analysis, samples were silylated
with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) (Sigma-
Aldrich, ≥ 99.0%) and kept at 60 °C for 1 h. The sample (0.2 µL)
was injected into the GC column (250 °C, 10.52 psi) with a
100:1 split ratio. The carrier gas was helium with a flow rate of
1.0 mL/min. The following gas chromatograph temperature
program was used for the study: 100 °C for 5 min, 300 °C (1
°C/min for 2 min). The product identification was confirmed
with a gas chromatograph-mass spectrometer (GC-MS).
All samples were characterized by X-ray diffraction (XRD), field
emission scanning electron microscopy with energy dispersive
X-ray spectroscopy (FESEM-EDX), nitrogen sorption (BET),
temperature programmed desorption (TPD), and thermal
gravimetric analysis (TGA). XRD patterns were collected on a
Kristalloflex 800 by Siemens at 25 mA and 30 kV with Cu Kα
radiation. Before measurements, the Ni-MOF/zeolite 5A bead
catalysts were ground by mortar and pestle into very fine
powders. FESEM images were taken on JEOL ISM-7000F using
a field emission gun and an accelerating voltage of 5 kV. N2
isotherms were collected in a Micromeritics Tristar-3000
porosimeter at 77 K using liquid nitrogen as coolant. Before
measurements, the samples were degassed at 180 °C for 6 h
under vacuum. TPD plots were acquired on a Micrometrics
Autochem 2920 instrument. Samples were pretreated under
helium at 120 °C for 1 h and then up to 300 °C for 1 h. The
samples were then exposed to 10 % NH3 gas in He, followed by
a temperature ramp to 100 °C to remove any physisorbed
species. The samples were then ramped at 30 °C min-1 from
120 to 300 °C to obtain the TPD curve. Data was normalized to
sample mass, and integrated using Micrometrics software
suite to obtain the quantity of NH3 adsorbed, which was
equated to acid site density using a 1:1 stoichiometry. TGA
profiles were obtained on a TGA Q50 under a constant flow of
Similar to our previous reports, the decarboxylation
conversion of the oleic acid was estimated from the reduction
in the number of oleic acid carboxylic acid groups during the
reaction.23-25 The amount of carboxylic acid groups remaining
in the products after the reaction was evaluated by quantifying
the acid number (ASTMD974). This acid number can be
estimated with the mass of potassium hydroxide (KOH) in
milligrams that is required to neutralize one gram of chemical
substance. To quantify the acid number, a known amount of
sample was dissolved in a solvent (ethanol and petroleum
ether), then titrated with a solution of sodium hydroxide
(NaOH, 0.1 N) using phenolphthalein as a color indicator.
The acid number was calculated from this equation:
NV
Acid number = 56.1
W
where N=0.1 (N); V=volume of NaOH consumed (mL); W=mass
of the sample (g).
The percent decarboxylation was calculated using the acid
number of oleic acid and acid number of the product using the
following relation: % Decarboxylation = (acid number of oleic
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acid – acid number of the product) / acid number of oleic acid
× 100%.
Figure 1 shows representative SEM images of all synthesized
Ni-MOF crystals. Ni-BM 65 and Ni-BM-73 crystals (Figure
1(b-c)) showed porous sphere-like structures with “raspberry”
morphology, whereas Ni-BTC crystals (Figure 1(a)) showed
Results and Discussion
irregular plate-like morphology with average widths of ∼10 μm
and lengths of varying size over 100 μm. The average size of
Ni-BM 65 crystals (Figure 1(b)) was 9.0 μm. Two different
particle sizes for Ni-BM 73 crystals (Figure 1(c)) were observed:
3.1 μm and 8.3 μm. To confirm the crystalline character of the
synthesized materials, XRD patterns of all prepared Ni-MOFs
were collected and shown in Figure 2. The materials do
present crystallinity, although the varied “sharpness” of the
XRD patterns for the three materials suggest varied degree of
crystallinity. In particular, the relative sharpness of the
patterns suggest that the larger molecule structure of the BM
65 and BM 73 linkers (as compared to BTC) led to overall lower
crystallinity. PXRDs for MOFs based on these two linker
present distinctive peaks at 2θ ∼33 ̊ and ∼36 ̊. Although, it was
not possible to experimentally solve the structure of the MOFs
synthesized here to unequivocally assign the origin of these
peaks, inspection of simulated XRD patterns in over 200 Ni-
MOFs obtained from the computation-ready, experimental
(CoRE) MOF database,26 clearly suggest that these peaks are
indicative of short range features such as Ni-Ni distances
(Figure S7 presents typical arrangements of Ni atoms in CoRE
MOFs).
The CoRE MOFs as a subset of structures identified as MOFs
derived from the Cambridge Structural Database (CSD)27 are a
good representation of MOFs synthesized to date. By
inspecting the linkers and crystallographic structures of the
over 200 Ni-based CoRE MOFs (Table S1), it is clear that Ni-BM
65 and Ni-BM 73 had not been previously synthesized. The
CoRE MOFs, on the other hand, revealed around 15 different
Ni-MOFs that have been synthesized based on the BTC linkers.
Thus, we proceeded to compare simulated XRD pattterns for
these CoRE MOFs with the pattern measured here for Ni-BTC
to determined whether our obtained Ni-BTC had been
previously synthesized and possibly determine the
crystallographic structure (Figure S7). This comparison
Fig. 1. Representative SEM images for Ni-MOF crystals (a) Ni-
BTC MOF; (b) Ni-BM 65 MOF and (c) Ni-BM 73 MOF.
discarded our Ni-BTC having the (3,4)-connected
tbo
topological network of the well-known Cu-BTC MOF,28 or
having a two dimensional structure. The closest match was
obtained with the Ni-BTC MOF synthesized by Prior and
Rosseinsky (CSD code: HUYJUG, see details in SI).29
(c)
(b)
(a)
The possible structures of the synthesized MOFs based on
search of the CORE MOF data base 26 and in silico construction
of MOF model using the ToBaCCo code 30 are described in the
Supporting Information (Figs. S8-S14). Based on the proposed
structures for Ni-BTC and Ni-BM65 (Figs. S9, and S14), a
perfect crystal of these MOFs would have a pore size of 11 Å
and 9 Å respectively (Figs. S11 and S16).
5
10
15
20
25
30
35
40
2 Theta (degree)
Fig. 2 XRD patterns for Ni-MOF crystals (a) Ni-BTC;
To confirm the porosity of the synthesized materials, the
surface areas of all studied Ni-MOFs were estimated applying
(b) Ni-BM 65 and (c) Ni-BM 73.
4 | J. Name., 2012, 00, 1-3
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BET theory to measured N2 isotherms and listed in Table 1. To Ni-MOF layers of 375, 538 and 415 μm thickness, respectively,
be certain of a meaningful comparison of BET areas for the for Ni-BTC, Ni-BM 65 and Ni-BM 73, respectively. XRD
synthesized is MOFs, we guided the BET area calculation with characterization for all catalysts showed the typical structure
four consistency criteria as detailed in ref. 31 (see calculation of zeolite 5A, which crystallizes in the LTA topology. Figures 5
details in Figures S18-S20).31 The BET areas ranged from 12 to (c-h) specifically confirm that the crystalline structure of
303 m2/g, with Ni-BTC presenting the lowest BET area. Given zeolite 5A was preserved after Ni-MOF deposition and
the pressumed small pore size of the three synthesized MOFs, recycling, indicating structural stability of the 5A bead
the BET area correlates well with pore volume (Figure S23) as supports.
expected.31 The lower observed experimental surface areas as
compared to simulated surface areas may be related to the
lower crystallinity of the samples and/or non optimal MOF
activation conditions. The thermal stability of the synthesized
MOFs was determined via TGA. As shown in Figure 3, it is
confirmed that the Ni-MOF crystals are thermally stable up to
(at least) 360 °C.
Table 1. BET area of studied Ni-MOFs
MOF Sample
Ni-BTC
BET area (m2/g) Pore volume (cm3/g)
12
0.02
0.45
0.89
Ni-BM 65
Ni-BM 73
175
303
100
80
60
40
20
0
Ni-BM 65 MOF
Ni-BTC MOF
Ni-BM 73 MOF
Fig. 4 SEM images for Ni-MOF/zeolite 5A bead catalysts (a) Ni-
BTC MOF/zeolite 5A; (b) Ni-BM 65 MOF/zeolite 5A and (c) Ni-
BM 73 MOF/zeolite 5A.
100 200 300 400 500 600 700 800
Temperature (degree C)
Fig. 3 TGA profiles for the studied Ni-MOF crystals.
(h)
(g)
(f)
After the described characterization of the MOFs was
completed, we proceeded to grow the resultant Ni-MOFs on
the surface of zeolite 5A beads, and to evaluate their catalytic
ability to decarboxylate oleic acid into liquid hydrocarbons.
Zeolite 5A is an aluminosilicate medium-pore-size molecular
sieve with acidic sites that is commercially available at a
relatively low cost. It is well known that acidic supports play an
important role in the decarboxylation reaction to obtain
improved heptadecane selectivities.32,33 In addition, as
compared to powders, beads are much easier to recycle and
can be fully recovered, and are therefore more amenable for
potential scale-up in catalytic applications.
(e)
(d)
(c)
(b)
(a)
5
10
15
20
25
30
35
40
2 Theta (degree)
Fig. 5 XRD patterns for catalysts (a) fresh zeolite 5A; (b) spent
zeolite 5A; (c) fresh Ni-BTC MOF/zeolite 5A; (d) spent Ni-BTC
MOF/zeolite 5A; (e) fresh Ni-BM 65 MOF/zeolite 5A; (f) spent
Ni-BM 65 MOF/zeolite 5A; (g) fresh Ni-BM 73 MOF/zeolite 5A
and (h) spent Ni-BM 73 MOF/zeolite 5A.
Figure
4 shows representative SEM images of the Ni-
MOF/zeolite 5A bead catalysts. The images show continuous
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conditions. The observed liquid product distribution for all the
The catalysts shown in Figure 4 were evaluated for the studied catalysts is summarized in Table 2. To clearly
decarboxylation of oleic acid to liquid hydrocarbons. High appreciate the role of the Ni-MOF catalysts, it is important to
conversion was observed (as high as 90% for decarboxylation) note that pure zeolite 5A beads provided heptadecane yields
for all catalysts employed (fresh and spent) under the reaction of only ~14%. Indeed, mainly short chain hydrocarbons (C7-C12)
Table 2 Liquid product distribution for all studied catalysts
Hydrocarbon distribution (%)
Catalysts
% DeCOx
Octadecane
8.18
Heptadecane
13.91
Hexadecane
2.12
Pentadecane Tetradecane
zeolite 5A
91.3
3.56
3.17
2.75
0.95
fresh Ni-BTC MOF/zeolite 91.2
1.64
70.11
2.21
5A
spent Ni-BTC MOF/zeolite 90.0
3.18
2.57
1.79
2.22
2.64
49.37
76.74
56.19
71.97
52.92
2.16
1.48
1.43
1.58
1.53
3.68
2.80
3.03
2.65
3.16
2.06
0.89
1.20
1.06
1.44
5A
fresh Ni-BM 65 MOF/zeolite 92.2
5A
spent
MOF/zeolite 5A
fresh Ni-
MOF/zeolite 5A
spent Ni-
Ni-
BM
BM
BM
65 90.4
73 90.3
73 90.1
MOF/zeolite 5A
Hydrocarbon distribution (%)
Catalysts
Tridecane
3.84
Dodecane Undecane Decane Nonane Octane Heptane Unknown
zeolite 5A
7.43
2.25
9.16
2.81
9.90
2.30
11.36
4.24
12.91
4.67
11.79
3.04
3.06
1.22
fresh Ni-BTC MOF/zeolite 1.39
5A
spent Ni-BTC MOF/zeolite 3.05
4.19
1.67
2.50
2.28
3.45
5.27
2.30
3.54
3.03
4.42
5.65
2.06
4.06
2.40
4.99
7.03
2.48
7.51
3.39
7.08
7.84
2.85
9.20
4.07
8.13
5.31
1.92
6.83
2.65
6.41
1.21
1.03
1.21
1.12
1.74
5A
fresh Ni-BM 65 MOF/zeolite 1.21
5A
spent
MOF/zeolite 5A
fresh Ni-
MOF/zeolite 5A
spent Ni-
MOF/zeolite 5A
Ni-
BM
BM
BM
65 1.50
73 1.58
73 209
Table 3 BET areas and pore volumes for fresh and spent Ni-MOF/zeolite 5A bead catalysts
Catalysts
BET area (m2/g)
Pore volume (cm3/g) Micropore volume (cm3/g)
Zeolite 5A
549
188
139
264
0.28
0.20
0.19
0.24
0.18
0.15
0.14
0.220
0.032
0.024
0.083
0.047
0.050
0.033
fresh Ni-BTC MOF/zeolite 5A
spent Ni-BTC MOF/zeolite 5A
fresh Ni-BM 65 MOF/zeolite 5A
spent Ni- BM 65 MOF/zeolite 5A 170
fresh Ni- BM 73 MOF/zeolite 5A 164
spent Ni- BM 73 MOF/zeolite 5A 129
were observed in the presence of pure zeolite 5A beads, which the liquid product included branched paraffins formed by
are generated through cracking of oleic acid and/or long chain isomerization of the initially formed heptadecane, and lower
hydrocarbons.34,35 Furthermore, the selectivity to heptadecane molecular weight hydrocarbons (mostly C7-C16 paraffins)
increased when zeolite 5A beads were coated with the Ni- formed by cracking of the heptadecane. The observed
MOFs, with the highest selectivity to n-heptadecane obtained products were: octadecane, heptadecane, dodecane,
with the Ni-BM 65/zeolite 5A catalyst. Other components in undecane, decane, nonane, octane, and heptane. A decrease
6 | J. Name., 2012, 00, 1-3
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of selectivity to n-heptadecane was observed for the spent
View Article Online
DOI: 10.1039/C7CY00564D
ARTICLE
catalysts (Table 2) likely the result of surface carbon deposited Table 4 The Ni content for all studied Ni-MOF/zeolite 5A bead
on the catalysts thus lowering subsequent activity. TGA catalysts
analysis indicates that indeed the amount of carbon present in
the spent catalysts is higher as compared to the fresh
catalysts. This observation is consistent with decreases in pore
volume for all studied catalysts (Table 3) which may prevent
access of oleic acid into the active sites. The Ni content of fresh
and spent Ni-MOF/zeolite 5A bead catalysts were estimated by
EDX. Importantly, the EDX results confirmed that there was
negligible Ni leaching for all recycled spent catalysts after
decarboxylation reactions (Table 4). The color of the final MOF
on bead catalyst in all cases (for fresh and spent catalysts) is
green, suggesting Ni2+ oxidation state.
Averaged Ni content
(wt%)
Catalysts
fresh Ni-BTC MOF/zeolite 5A
spent Ni-BTC MOF/zeolite 5A
fresh Ni-BM 65 MOF/zeolite 5A
27.49±1.46
27.07±2.73
27.67±2.79
spent Ni- BM 65 MOF/zeolite 5A 27.23±1.55
fresh Ni- BM 73 MOF/zeolite 5A 28.21±2.94
spent Ni- BM 73 MOF/zeolite 5A 27.20±2.06
The acid sites on the as-prepared and spent MOF/zeolite 5A
catalysts are summarized in Table 5. Fresh catalyst exhibited
significantly higher acidity than the corresponding spent
catalyst. Post-catalysis samples show approximately a 50%
decrease in acid site content, except for Ni-BM 73 MOF/zeolite
5A, which shows negligible change. Ni-BM 73 also shows a
reduction in the temperature of the peak desorption. The
higher temperature desorption peak observed for Ni-BM73 is
likely associated to free carboxylic acids of the linker that have
not crystalized into the MOF framework due to the asymmetry
of the linker.36
Table 5 Summary of acid site density data from TPD of NH3
post catalysis
Tmax Acid site density
Catalysts
(°C)
(μmol/g)
zeolite 5A
255 1451
213 952
206 494
205 1382
fresh Ni-BTC MOF/zeolite 5A
spent Ni-BTC MOF/zeolite 5A
fresh Ni-BM 65 MOF/zeolite 5A
spent Ni- BM 65 MOF/zeolite 5A 196 423
fresh Ni- BM 73 MOF/zeolite 5A 300 456
spent Ni- BM 73 MOF/zeolite 5A 196 441
The desorption temperature of ammonia suggest somewhat
higher Lewis acidity for Ni BTC than for Ni BM65. This is
consistent with DFT-calculated charges of Ni in the nodes of
the proposed structures for Ni BTC (Ni = + 0.95) and for Ni BM
65 (Ni = +0.56, + 0.73) as shown in Fig. S17
Table 6 Comparison of the catalytic conversion of oleic acid to heptadecane through different catalystsa
Mass
ratio of
Heptadecane
Conversion
(%)
Entry Catalyst
Reaction conditions
metal to
selectivity
(%)
Ref
oleic
acid
1
Activated carbon
T=370 °C, t=3 h
-
80±4
88.1
100.0
93.0
81.9
85.7
98
7±1
6.1
1
2
Co0.5Mo0.5
T=300 °C, t=3 h
1:40
5
3
5CoAl
T=330 °C, P=50 bar, LHSV=2 h-1
T=330 °C, P=50 bar, LHSV=2 h-1
T=320 °C
-
47.0
25.5
76.0
75.5
6.93
11
9
4
5NiAl
-
9
5
Sulfide Mo/P/Al2O3
Sulfide NiW/Al2O3
MgO-Al2O3
-
10
6
T=340 °C
-
10
7
T=400 °C
1:42
1:40
-
11
8
Ce0.6Zr0.4O2
T=300 °C, t=6 h
94.6
-
12
9
Mo/Zeol
T=360 °C, P=20 bar, t=1 h
T=300 °C, t=6 h
19
37
10
11
12
13
14
15
16
17
SnAlMg-2
1:75
1:21505
1:4.7
1:44
-
71.1
-
3.7
38
Ni/Al2O3
T=360 °C, P=20 bar, t=0.75 h
T=290 °C, P=30 bar, t=6 h
4 h in super-critical water
T=370±2 °C, P=241 bar
T=380 °C, P=71.5 bar, LHSV=0.45 h-1
T=280 °C, P=30 bar, t=6 h
T=340 °C, P=20 bar, t=2 h
10
39
Fe-MSN
100
97.3
99.4±0.5
99.9
100
91.1
12
40
NiWC/Al-SBA-15
Activated carbon
Mo2N/γ-Al2O3
Ni/ZnO-Al2O3
Ni-BM 65 MOF/zeolite 5A
5.2
41
80.6±4
12
42
-
43
1:100
1:33
95.1
76.7
44
this study
aOnly the best catalytic performance of each reference is shown in Table 6. Note: in entries 8, 9, 11, 12, 15 and 16, hydrogen is
used.
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The high aptitude towards selective oleic acid decarboxylation hydrogen (we employed CO2,
a
lower cost renewable
to heptadecane of these structurally disordered MOFs does feedstock), that has higher potential as a viable commercial
not correlate with the density of sites. The zeolite 5A support process. The benefit of using CO2 gas atmosphere was
shows comparable acidity with Ni-BTC and Ni-BM 65, but reported in our previous research.25
minimal heptadecane yield. Therefore, Ni must play a key role
in the catalytic decarboxylation of oleic acid. Interestingly,
Conclusions
heptadecane yield scaled with micropore volume. As we move
from BTC to BM 73 to BM 65 the length of the linker increases
leading to progressively larger micropore volumes. Larger
linkers can facilitate mass transport of the substrate and the
product increasing observed yield.
We have demonstrated the successful synthesis of nickel
based metal organic frameworks (Ni-MOFs) employing novel
carboxylic acid linkers. Furthermore, the deposition of these
MOFs on zeolite 5A beads was illustrated and shown to
produce catalytically active materials for the conversion of
oleic acid into liquid hydrocarbons. The resultant Ni-
MOF/zeolite 5A bead catalysts displayed heptadecane
We ran a reaction with a homogeneous catalyst consisting of
Nickel nitrate hexahydrate and BM-65 MOF linker (reaction
conditions: T=340 °C, P=20 bar, CO2 atmosphere, t=2 h) and
mass ratio of catalyst to oleic acid 1:1. The conversion was
~94%, with much lower selectivity to heptadecane (47.7%).
These results suggest that indeed the presence of a MOF
structure (and porosity) is needed to observe higher
heptadecane selectivities (Table 6).
selectivity as high as
∼77%. All of the studied catalysts
displayed a loss in catalytic activity after recycling. This is likely
due to surface carbon that deposited during the reaction,
resulting in the loss of surface area and pore volume. Our
efforts demonstrate that it is possible to obtain effective
catalytic decarboxylation of fatty acid with non-noble metal-
based catalysts. Indeed, to the best of our knowledge the
catalytic performance of Ni-BM 65 MOF/zeolite 5A bead
catalyst is superior to all non-noble metal state-of-the-art
catalysts at mild reaction conditions. We also show that the
use of CO2 during reaction may lead to a more viable and cost
effective route to catalytically convert fatty acid methyl esters
into alternative liquid fuels. We envision the presented work
will encourage synthesis and study of MOFs based on earth-
abundant metals for catalytic applications.
In addition, we evaluated the catalytic activity of Ni-BM 65
MOF powders. The Ni-MOF powders displayed good catalytic
ability (~90% conversion and ~73% heptadecane selectivity).
This performance was slightly lower than the Ni-BM 65
MOF/zeolite 5A (entry 17 on Table 6). We have demonstrated
32,23
24
previously that acid supports
including 5A zeolite
help
to improve heptadecane selectivities. Therefore, both Ni- BM
65 MOF and zeolite 5A play an important role as active sites
for the decarboxylation of oleic acid to heptadecane. Further
studies are needed to elucidate the specific role of each of
them for this particular reaction. It is important to mention
that only ~50% of the Ni-BM 65 powders were recovered after
reaction, while 100% of the Ni-BM 65 MOF/zeolite 5A was
recovered after reaction.
Acknowledgements
This research was supported by the Renewable Energy
Materials Research Science and Engineering Center (REMRSEC)
under Award Number DMR-0820518, and by startup funds
from Colorado School of Mines (CSM). B.W.M. respectfully
acknowledges the sponsorship and support of the United
States Air Force Institute of Technology.
Table
6 compares the state-of-the-art non-noble metal
catalysts that have been employed specifically for the catalytic
conversion of oleic acid to heptadecane.1,5,9,10-12,37-44 Sulfide
Mo/P and NiW supported on Al2O3 had similar catalytic
performance
(76% selectivity to heptadecane) as Ni-BM 65
MOF/zeolite 5A bead catalyst.10 However, the use of sulfur
based catalysts may result in sulfide contamination leading to
serious environmental issues. Activated carbon shows high
selectivity to heptadecane 80%). However, to achieve this the
pressure as high as 241 bar and temperature of 370 °C are
needed.42 Ni supported on ZnO and Al2O3 has displayed
heptadecane selectivities higher than 95%, but the reaction
requires higher pressure and longer reaction times (30 bar and
6 hours).44 Importantly, in our study we did not employ
References
1
2
3
J. Fu, F. Shi, L. T. Thompsom Jr., X Lu and P. E. Savage, ACS
Catal., 2011, , 227.
1
S. De, B. Saha and R. Luque, Bioresour. Technol., 2015, 178
,
108.
D. R. Vardon, B. K. Sharma, H. Jaramillo, DW Kim, JK Choe, P.
N. Ciesielski and T. T. Strathmann, Green Chem., 2014, 16
,
1507.
K. Hengst, M. Arend, R. Pfützenreuter and W. F. Hoelderich,
Appl. Catal., B, 2015, 174-175, 383.
4
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 8
Please do not adjust margins

Please do not adjust margins
Catalysis Science & Technology
Page 9 of 10
Journal Name
View Article Online
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ARTICLE
5
JO Shim, DW Jeong, WJ Jang, KW Jeon, SH Kim, BH Jeon, HS 34 R. Černý, M. Kubů and D. Kubička, Catal. Today, 2013, 204,
Roh, JG Na, YK Oh, SS Han and CH Ko, Catal. Commun., 2015,
67, 16.
R. C. Striebich, C. E. Smart, T. S. Gunasekera, S. S. Mueller, E.
46.
35 N Ma, W. Tandar and P. E. Savage, J. Supercrit. Fluids, 2015,
102, 73.
6
M. Strobel, B. W. McNichols and O. N. Ruiz, Int. Biodeterior. 36 X Wei, YM Wang, R. Bergsträßer, S. Kundu and M. Muhler,
Biodefradation, 2014, 93, 33. Appl. Surf. Sci., 2007, 254, 247.
M. Snåre, I. Kubičková, P. Mäki-Arvela, K. Eränen and D. Y. 37 O. B. Ayodele, H. U. Farouk, J. Mohammed, Y. Uemura and
Murzin, Ind. Eng. Chem. Res., 2006, 45, 5708. W. M. A. W. Daud, J Taiwan Inst Chem Eng, 2015, 50, 142.
A. S. Berenblyum, R. S. Shamsiev, T. A. Podoplelova and V. Y. 38 DS Tong, CH Zhou, MY Li, MY Li, WH Yu, J. Beltramini, CX Lin
Danyushevsky, Russ. J. Phys. Chem. A, 2012, 86, 1199. and ZP Xu, Applied Clay Science, 2010, 48, 569.
A. Srifa, K. Faungnawakij, V. Itthibenchapong and S. 39 O. B. Ayodele, K. C. Lethesh, Z. Gholami and Y. Uemura,
Assabumrungrat, Chem. Eng. J, 2015, 278, 249. Journal of Energy Chemistry, 2016, 25, 158.
10 T. Szarvas, Z. Eller, T. Kasza, T. Ollár, P. Tétényi and J. 40 K. Kandel, J. W. Anderegg, N. C. Nelson, U. Chaudhary and I.
Hancsók, Appl. Catal., B, 2015, 165, 245. I. Slowing, J. Catal., 2014, 314, 142.
11 JG Na, BE Yi, JN Kim, KB Yi, SY Park, JH Park, JN Kim and CH 41 B. A. Alwan, S. O. Salley and K. Y. Simon Ng, Appl. Catal., A,
Ko, Catal. Today, 2010, 156, 44. 2015, 498, 32.
7
8
9
12 JO Shim, DW Jeong, WJ Jang, KW Jeon, BH Jeon, SY Cho, HS 42 S. Popov and S. Kumar, Energy Fuels, 2015, 29, 3377.
Roh, JG Na, CH Ko, YK Oh and SS Han, Renewable Energy, 43 J. Monnier, H. Sulimma, A. Dalai and G. Caravaggio, Appl.
2014, 65, 36.
13 D. A. Gómez-Gualdrón, Y. J. Colón, X Zhang, T. C. Wang, YS 44 GC Li, F Zhang, L Chen, CH Zhang, H Huang and XB, Li,
Chen, J. T. Hupp, T. Yildirim, O. K. Farha, J Zhang and R. Q. ChemCatChem, 2015, , 2646.
Snurr, Enery Environ. Sci., 2016, , 3279.
14 J. Gascon, A. Corma, F. Kapteijn and F. X. Llabrés I Xamena,
ACS Catal., 2014, , 361.
Catal., A, 2010, 382, 176.
7
9
4
15 O. K. Farha, I. Eryazici, NC Jeong, B. G. Hauser, C. E. Wilmer,
A. A. Sarjeant, R. Q. Snurr, S. T. Nguyen, A. Özgür Yazaydın
and J. T. Hupp, J. Am. Chem. Soc., 2012, 134, 15016.
16 J. H. Cavka, S. Jakobsen, U. Olsbye, N. Guillou, C. Lamberti,
S.Bordiga and K. P. Lillerud, J. Am. Chem. Soc., 2008, 130,
13850.
17 J. E. Mondloch, W. Bury, D. Fairen-Jimenez, S. Kwon, E. J.
DeMarco, M. H. Westom, A. A. Sarjeant, S. T. Nguyen, P. C.
Stair, R. Q. Snurr, O. K. Farha and J. T. Hupp, J. Am. Chem.
Soc., 2013, 135, 10294.
18 K. S. Park, Z. Ni, A. P. Côté, J. Y. Choi, R. Huang, F. J. Uribe-
Romo, H. K. Chae, M. O'Keeffe and O. M. Yaghi, PNAS, 2006,
103, 10186.
19 G. Férey, Chem. Soc. Rev., 2008, 37, 191.
20 L. MacGillivray, Metal Organic Framework: Design and
Application, John Wiley & Sons. Inc., 2010.
21 R. W. Gosselink, S. A. W. Hollak, SW Chang, J. van Haveren, K.
P. de Jong, J. H. Bitter and D. S. van Es, ChemsusChem, 2013,
6, 1576.
22 JH Wu, JJ Shi, J Fu, J.A. Leidl, ZY Hou and XY Lu, Sci. Rep.,
2016, DOI: 10.1038/srep27820.
23 L Yang, G. L. Ruess and M. A. Carreon, Catal. Sci. Technol.,
2015,
24 LQ Yang, K. L. Tate, J. B. Jasinski and M. A. Carreon, ACS
Catal., 2015, , 6497.
5, 2777.
5
25 LQ Yang and M. A. Carreon, J. Chem. Technol. Biotechnol.,
2017, 92, 52.
26 Y. G. Chung, J. Camp, M. Haranczyk, B. J. Sikora, W. Bury, V.
Krungleviciute, T. Yildirim, O. K. Farha, D. S. Sholl and R. Q.
Snurr, Chem. Mater., 2014, 26, 6185.
27 The
Cambridge
https://www.ccdc.cam.ac.uk/
Structural
Database
(CSD)
28 SS Chui, S. M. Lo, J. P Charmant, A. G. Orpen and I. D.
Williams, Science, 1999, 283, 1148.
29 T. J. Prior and M. J. Rosseinsky, Inorg. Chem., 2003, 42, 1564.
30 D.A.Gomez-Gualdron, Y.J.Colon,
X. Zhang, T.C. Wang, Y.S. Chen, J.T. Hupp, T. Yildirim, O. K.
Farha, J. Zhang, R.Q. Snurr,Energy Environ. Sci. 2016, 9, 3279.
31 D. A. Gómez-Gualdrón, P. Z. Moghadam, J. T. Hupp, O. K.
Farha and R. Q. Snurr, J. Am. Chem. Soc., 2016, 138, 215.
32 M. Ahmadi, E. E. Macias, J. B. Jasinski, P. Ratnasamy and M.
A. Carreon, J. Mol. Catal. A: Chem., 2014, 386, 14.
33 M. Ahmadi, A. Nambo, J. B. Jasinski, P. Ratnasamy and M. A.
Carreon, Catal. Sci. Technol., 2015, 5, 380.
This journal is © The Royal Society of Chemistry 20xx
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Herein we demonstrate novel free-noble metal catalytic systems based on Ni MOFs that can
effectively convert oleic acid into heptadecane.