Isomerization and Selective Hydrogenation of Propyne: Screening of Metal-Organic Frameworks Modified by Atomic Layer Deposition

Article abstract of DOI:10.1021/jacs.0c08641

Various metal oxide clusters upward of 8 atoms (Cu, Cd, Co, Fe, Ga, Mn, Mo, Ni, Sn, W, Zn, In, and Al) were incorporated into the pores of the metal-organic framework (MOF) NU-1000 via atomic layer deposition (ALD) and tested via high-throughput screening

Full text of DOI:10.1021/jacs.0c08641

pubs.acs.org/JACS
Article
Isomerization and Selective Hydrogenation of Propyne: Screening
of Metal−Organic Frameworks Modified by Atomic Layer Deposition
Ryan A. Hackler,$ Riddhish Pandharkar,$ Magali S. Ferrandon, In Soo Kim, Nicolaas A. Vermeulen,
Leighanne C. Gallington, Karena W. Chapman, Omar K. Farha, Christopher J. Cramer, Joachim Sauer,*
Laura Gagliardi,* Alex B. F. Martinson,* and Massimiliano Delferro*
Cite This: https://dx.doi.org/10.1021/jacs.0c08641
Read Online
sı
*
Metrics & More
Article Recommendations
Supporting Information
ACCESS
ABSTRACT: Various metal oxide clusters upward of 8 atoms
(Cu, Cd, Co, Fe, Ga, Mn, Mo, Ni, Sn, W, Zn, In, and Al) were
incorporated into the pores of the metal−organic framework
(MOF) NU-1000 via atomic layer deposition (ALD) and tested
via high-throughput screening for catalytic isomerization and
selective hydrogenation of propyne. Cu and Co were found to be
the most active for propyne hydrogenation to propylene, and
synergistic bimetallic combinations of Co and Zn, along with
standalone Zn and Cd, were established as the most active for
conversion to the isomerized product, propadiene. The combina-
tion of Co and Zn in NU-1000 diminished the propensity for full
hydrogenation to propane as well as coking compared to its individual components. This study highlights the potential for high-
throughput screening to survey monometallic and bimetallic cluster combinations that best affect the efficient transformation of
small molecules, while discerning mechanistic differences in isomerization and hydrogenation by different metals.
alkanes.10−12 MOFs are crystalline porous materials comprised
INTRODUCTION
■
of a metal node and organic linker molecules with accessible
Selective hydrocarbon catalysis is vital for the production of
functional groups within the pores.13 The well-defined
fuels and chemical intermediates needed in various indus-
structure and porosity of MOFs mean this unique class of
tries.1,2 Selective alkyne hydrogenation, for example, is
materials is well-equipped to act as a scaffold for catalytically
necessary in alkene polymerization processes to avoid both
active and uniform metal clusters. Metal nanoparticles and
poisoning of the catalyst by alkyne impurities and full
clusters possess unique catalytic properties due to their size,14
hydrogenation to low-value alkane products.3 Generally, the
so any synthetic approach that can produce uniform active
alkyne impurities in the olefin feed competitively bind to the
sites on a viable support proves invaluable for producing
active sites of the catalyst, preventing adsorption and
selective catalysts and studying the mechanisms behind the
polymerization of the alkene.4,5 Isomers like the corresponding
active sites. MOFs can behave as selective hydrocarbon
allene usually require partial hydrogenation in polymerization
transformation catalysts when coupled with a developed and
catalysis as well, as the diene also acts as a potent poison.
thorough understanding of how to deposit metal clusters.
Selective conversion of alkynes to the diene isomer, however,
In this study, NU-1000 was chosen as the MOF to support
can produce other important chemical intermediates needed
the various metal oxide species. NU-1000 is a zirconium based
en route to various classes of pharmaceuticals such as
MOF with [Zr6(μ3-O)4(μ3-OH)4(OH)4(OH2)4]8+ nodes and
steroids.6,7 In the case of selective alkyne isomerization, base-
tetratopic 1,3,6,8-tetrakis(p-benzoate)pyrene linkers (Figure
mediated homogeneous and heterogeneous catalysis has only
1).15 Hydroxyl (−OH) and aquo (−OH2) groups reside at the
been shown to exhibit up to 15% selectivity for simple
Zr node within 31 Å sized pores and allow for the
allenes.8,9 Generally, this is due to simple alkynes being
incorporation of various metals through postsynthetic
thermodynamically more favorable than their isomers. The
isomerization mechanism involves either a carbocation or
carboanion intermediate depending on how protons are
Received: August 11, 2020
abstracted via the active site.
Recent investigations into the use of metal−organic
frameworks (MOFs) as tunable supports for single-site metal
catalysts have shown great promise for the selective trans-
formation of a multitude of hydrocarbons, including light
https://dx.doi.org/10.1021/jacs.0c08641
© XXXX American Chemical Society
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX
A

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
then suspended in 13 mL of DMF, and 0.5 mL of 8 M HCl was added
to this mixture to acid-activate the zirconium node. This mixture was
heated in an oven at 100 °C for 24 h. After being cooled to room
temperature, the supernatant was removed by centrifuge, and the
material was washed twice with fresh DMF. Subsequently, the solid
materials were washed twice with acetone and soaked in acetone for
an additional 12 h. Then the acetone was removed by centrifugation,
and the solid was briefly dried in an oven at 80 °C. The solid material
was activated on a SmartVacPrep station (Micromeritics) under
dynamic vacuum at 120 °C until an outgassing rate of ≤0.002 mmHg
min−1 was reached.
Atomic Layer Deposition in Metal−Organic Frameworks
(AIM). Hydration of NU-1000 was conducted using a modified
procedure described previously.26 In each AIM experiment, 10−60
mg of NU-1000 powder was heated to 115 °C under a rough vacuum
with a continuous flow of 20 sccm nitrogen (N2) resulting in 0.4 Torr
base pressure−standard “purge” conditions. After 10 min of purge
conditions to remove any physisorbed water, the powder was
reproducibly hydroxylated and hydrated with a 60 s exposure to
water vapor using a pulse sequence of t1-t2-t3 (pulse−exposure−
purge), where t1 = 1 s, t2 = 59 s, t3 = 60 s. Subsequently, the powder
was purged for 5 min again to remove physisorbed water and obtain a
reproducible − OH and − OH2 population.
After the sample preparation procedure outlined above, exposure to
a variety of volatile organometallic precursors afforded the metal-
modified MOFs tested for catalysis. A complete list of the ALD
procedures used can be found in the SI. In one example, Co-AIM was
performed by introducing dicarbonyl(cyclopentadienyl) cobalt(I)
(Strem Chemicals, min. 95%) into the reaction chamber using the
pulse sequence as for water, but with standard pulse times of t1 = 0.75
s, t2 = 59.25 s, and t3 = 60 s. Following 80 repeated exposures of
CpCo(CO)2, which constitute a single ALD half-cycle, the sample
was left to purge for an additional 5 min to ensure a complete removal
of any excess precursor and/or reaction byproducts within the pores
of NU-1000. The powder was subjected to 60 doses of water vapor
according to the previous dosing schedule but with shorter pulse
length (0.1 s) in order to minimize the effects of MOF heating
expected from the strongly exothermic heat of reaction.27 The metal
loading of each resulting AIM is summarized below in Table 1. The
production of the A-B AIMs (i.e., Co−Co AIM, Co−Zn AIM, Zn−
Co AIM, and Zn−Zn AIM) was achieved by performing a single ALD
cycle each of A-AIM followed by B-AIM.
High-Throughput Catalyst Testing. Selective hydrogenation of
propyne was performed in a 16 fixed bed reaction system (Flowrence,
Avantium). Typically, 5 mg of as-prepared catalyst was diluted with
50 mg nonporous silica gel (Davisil 230−400 mesh) and loaded into a
quartz reactor (inner diameter = 2 mm, outer diameter = 3 mm,
length = 300 mm). The silica diluent showed no catalytic activity in
control experiments. Reactions were performed between 50 and 300
°C at a heating rate of 5 °C/min and pressure ranged from 1 to 10
atm. All gases were purchased from Airgas. 2% propyne in Ar was
used with 3.5% H2 in Ar for selective hydrogenation experiments. N2
(ultrahigh purity (UHP)) was sometimes added to keep a constant
gas hourly space velocity (GHSV) and was also used to sweep gas to
the gas chromatograph (GC) after reaction. He (UHP) was used as
the standard for GC. Flow rates of 5.3 mL/min of 2% propyne in Ar,
3.1 mL/min of 3.5% H2 in Ar, and 1 mL/min He were used per
reactor giving a propyne/H2 ratio of 1 and a GHSV of 3015 h−1.
Additional experiments were conducted at flow rates of 2.8 mL/min
of 2% propyne in Ar, 3.1 mL/min of 3.5% H2 in Ar, 2.5 mL/min N2,
and 1 mL/min He per reactor giving a propyne/H2 ratio of 2 and a
GHSV of 3015 h−1.
Figure 1. Reaction scheme for selective propyne isomerization and
hydrogenation to alkenes via AIM catalysts, with the idealized AIM
structure shown to the left. Metal ions (denoted M) attached onto the
Zr6 oxide node include Cu, Cd, Co, Fe, Ga, Mn, Mo, Ni, Sn, W, Zn,
In, and Al.
modification.16 These modifications can be undertaken
through atomic layer deposition (ALD): a vapor-phase
technique used to synthesize thin films, nanoparticles, and
single atom catalysts of various compositions on a myriad of
supports.17 Metalation of MOFs via reaction with volatile
metalorganics or ALD in MOFs (AIM) has been leveraged for
the construction of hydrocarbon catalysts for hydrogenation of
ethylene and m-nitrophenol, oxidative dehydrogenation of
propane, and dehydration of ethanol.18−22 The promise of
AIM catalysts lies in the potential to synthesize small metal
clusters of various compositions with precision in the size and
nature of the cluster. Metal clusters can range in size from one
to several atoms within a single pore. The size of the pore also
allows for enhanced selectivity of the reactant for trans-
formation.23
In this work, various metals including Cu,24,25 Cd,25 Co,25
Fe,25 Ga,25 Mn,25 Mo,25 Ni,19 Sn,25 W,25 Zn,16,25 In,25 and
Al21,25 were incorporated into NU-1000 using methods
described previously and fully characterized. The postsyntheti-
cally modified MOFs were monitored at various temperatures
(50−300 °C) for propyne hydrogenation to propylene via
high-throughput screening. Simultaneously, the isomerization
product was observed under hydrogenation conditions.
Bimetallic combinations of Co−Zn and Zn−Co were also
explored for any synergistic effects. Thermogravimetric and
metal loading analyses were performed to provide insight into
the active site environment. Isomerization and hydrogenation
pathways for Cu and Zn AIMs were then determined, and their
energies were calculated via density functional theory (DFT).
This work showcases a comprehensive suite of AIM catalysts
and explores their activity and selectivity for propyne
transformation.
EXPERIMENTAL SECTION
■
Synthesis of NU-1000. ZrOCl2·8H2O (97 mg, 0.30 mmol) and
benzoic acid (2.70 g, 22 mmol) were mixed in 8 mL of DMF (in a 6-
dram vial) and dissolved using sonication. The clear solution was
incubated in an oven at 80 °C for 1h. After being cooled to room
temperature, 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy, 40
mg, 0.06 mmol) was added to this solution and the mixture was
sonicated for 10 min. The yellow suspension was heated in an oven at
100 °C for 18 h. After being cooled to room temperature, a yellow
NU-1000 precipitate was collected by centrifugation (7800 rpm, 5
min) and washed with fresh DMF twice. As synthesizedNU-1000 was
The effluent of each reactor was analyzed sequentially by a gas
chromatograph (7890B, Agilent Technologies), equipped with a
Table 1. Metal Atoms Per Zr6 Node for Each Single-Cycle AIM as Determined by ICP-OES25
Metal
Cu
4.5
Cd
3.3
Co
2.8
Fe
Ga
4.2
Mn
7.3
Mo
4.5
Ni
Sn
W
Zn
4.2
In
Al
Loading (metal atoms/node)
3.4
3.3
4.7
5.0
4.3
7.0
B
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
thermal conductivity detector (TCD) and 2 flame ionization
detectors (FID). The gas products identified were acetylene, ethylene,
ethane, propadiene, propylene, and propane from the reactions as
follows
frequencies below 50 cm−1 to 50 cm−1 when calculating the
vibrational partition function. All thermodynamic quantities were
calculated at 1.0 atm pressure and 1 M concentrations for all
reactants. We performed single point calculations using two hybrid
functionals, M0638 and B3LYP39, for select reaction pathways.
Dispersion corrections using the D3(BJ)40 method were added to
the B3LYP but not to the M06 and M06-L functionals, as these have
long-range dispersion terms built-in the functional.38,41 Figures S24−
S26 show that the relative electronic energies for M06-L, M06 and
B3LYP-D3(BJ) show similar trends.
A cluster model (Figure S1) was obtained by extracting one node,
[Zr6(μ3-O)4(μ3−OH)4(OH)4(OH2)4]8+, from a Zr-NU-1000 crystal
structure optimized with periodic boundary conditions.42 The node
was capped with formate anions that replace the linkers, [Zr6(μ3-
O)4(μ3−OH)4(OH)4(OH2)4](HCOO)8, and the positions of the
carbon atoms of the linker were kept frozen to model the constraints
by the MOF framework. The model of the catalyst was obtained by
adding the metal (+2) cation on one face of the node, [M Zr6(μ3-
O)5(μ3−OH)3(OH)5(OH2)3](HCOO)8. The water molecule and
the μ-hydroxy groups on the face of the cluster with the metal atom
were deprotonated to maintain neutrality of the cluster. This
deprotonation is part of the ALD mechanism of the synthesis of
the catalyst, based on previous work,19 and does not affect the free
energies of the catalytic reactions. The other three faces of the node
were dehydrated by removing 3 water molecules, and 3 terminal
hydroxyls, and 3 μ-oxo protons, [M Zr6(μ3-O)8(OH)2](HCOO)8.
The doublet and singlet spin states were considered for Cu2+(d9)
and Zn2+(d10), respectively. The optimized structures, single point
energies, and thermodynamic quantities for each structure are
reported in the SI.
Isomerization: C3H4(g)(propyne) → C3H4(g)(propadiene)
ΔHr = 3.8 2.1 kJ/mol
Acetylene Formation: C3H4(g)(propyne) + H2(g)
→ C2H2(g)(acetylene) + CH4(g)
Complete Hydrogenation: C3H4(g)(propyne) + 2H2(g)
→ C3H8(g)(propane) ΔHr = −289.2 kJ/mol
ΔHr = −33.6 kJ/mol
C2H2(g)(acetylene) + 2H2(g) → C2H6(g)(ethane)
ΔHr = −310.5 kJ/mol
PartialHydrogenation: C3H4(g)(propyne) + H2(g)
→ C3H6(g)(propene)
ΔHr = −165 kJ/mol
C2H2(g)(acetylene) + H2(g) → C2H4(g)(ethene)
ΔHr = −174.2 kJ/mol
Initially, the catalysts were not pretreated; however, for the durability
experiments, the catalysts were pretreated in 3.5% H2 in Ar at 200 °C
for 2 h.
PXRD of Metalated NU-1000 Samples. Powder X-ray
diffraction (PXRD) patterns were taken on a Bruker Advance D8
Powder X-ray diffractometer with Ni-filtered Cu Kα radiation
operating at 40 kV and 40 mA. The scan range was between 2°
and 20° with 0.01° steps at a collection speed of 1 s/step.
ICP-OES of Metalated NU-1000 Samples. The number of
metal atoms per Zr6 node was confirmed using a ThermoFisher
Scientific iCAP 7200 inductively coupled plasma-optical emission
spectrometry (ICP-OES) system; ∼1 mg of metalated NU-1000 was
dissolved using 1 mL Piranha solution (3:1 99.999% sulfuric acid to
30 wt % hydrogen peroxide solution) in a 25 mL volumetric flask
followed by a gentle sonication. Caution: since Piranha solution
(H2SO4/30% H2O2, 7:3) reacts violently with many organic
compounds, extreme care must be taken when handling it. Once
metalated NU-1000 was fully dissolved, 24 mL of RO water was
added for ICP-OES measurements.
Thermogravimetric Analysis (TGA) of Metalated NU-1000
samples. TGA of around 5 mg of sample was performed using a
Discovery (TA Instruments) under a flow of N2 of 10 mL/min at a
heating rate of 5 °C/min from room temperature to 300 °C, followed
by 1 h at 300 °C.
Difference Envelope Density (DED) Analysis. X-ray powder
diffraction data were collected at beamline 11-ID-B of the Advanced
Photon Source at Argonne National Laboratory using high energy X-
rays (λ = 0.2114 Å). The detector geometry was calibrated and X-ray
scattering images were reduced to one-dimensional diffraction data
within GSAS-II.28 The peak intensities in the diffraction data were
quantified via Le Bail whole-pattern fitting29 based on the reported
structural model for NU-1000 (csq topology, P6/mmm, a ∼ 40 Å, c ∼
17 Å). Structure envelopes were generated using the intensities of
low-index reflections.30,31 DEDs were then obtained via subtraction of
the envelope for pristine NU-1000 from the envelope for ALD
modified NU-1000 as described previously.32,33
RESULTS AND DISCUSSION
■
An initial survey of ALD-prepared metal-modified MOFs
determined the most viable catalysts for selective propyne
conversion to propadiene and propylene. NU-1000 was
exposed to the appropriate ALD precursor to append Cu,
Cd, Co, Fe, Ga, Mo, Ni, Sn, W, Mn, Zn, In, and Al to the
zirconium node. The synthesis, structure, and electronic
structure of the resulting metal cluster for many AIMs has
already been established in previous literature, including Al,21
Co,20 Cu,24 In,26 Ni,19 and Zn.25,33 Techniques such as
difference envelope density (DED) analyses have elucidated
the location of metal clusters such as Co, whereas pair
distribution function (PDF) analyses have evaluated changes
to the local metal cluster environment, such as MOF node
distortions. Scanning electron microscopy (SEM), energy-
dispersive X-ray spectroscopy (EDX), transmission electron
microscopy (TEM), and X-ray photoelectron spectroscopy
(XPS) were also conducted on these catalysts to provide full
structural detail after ALD modification. Previously unpub-
lished DED analysis of the In, Ni, and Mn AIMs are also
provided in the SI. These combined results show metal cluster
formation primarily in the ∼8 Å channels and little to no node
distortion. All the catalysts previously studied included
multiple metal atoms per zirconium node (ranging from 2−
8), and only the most reactive of ALD precursors (e.g., AlMe3)
resulted in a degradation of crystallinity in the MOF.
Precursors were chosen for the catalysts herein such that no
degradation in crystallinity was observed within one ALD
cycle.
Computational Details. Geometry optimizations and frequency
calculations were performed using the M06-L local density func-
tional34 and an automatic density fitting on the ultrafine grid in
Gaussian 09 software package.35 The Def2-SVP basis was used for the
C, H, O atoms and Def2-TZVP basis for the transition metals (Cu,
Zn, Zr).36 The SDD pseudopotential was used for the Zr atoms in the
node.37 Vibrational frequency calculations were performed for each
optimized structure to verify the nature of each stationary point and
to calculate thermochemical quantities at 300 °C after setting up all
Two sequential cycles of Mn (Mn−Mn), Zn (Zn−Zn), Co
(Co−Co) or sequential cycles of Co and Zn (Co−Zn and Zn−
Co) were also implemented to afford additional local metal
environments. The sequencing of metal deposition appears to
have a small effect on the loading of heterobimetallic AIMs.
For example, Co−Zn contained 1.65 Co/Zr6 node and 3.82
C
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
Figure 2. Propyne conversion (A) and propadiene yield (B) for various AIMs as a function of reaction temperature.
Zn/Zr6 node, whereas Zn−Co contained 0.57 Co/Zr6 node
and 3.58 Zn/Zr6 node. This is likely due to minute differences
in the viable −OH sites of Zn clusters compared to Co clusters
during nucleation. The highest selectivity to propadiene, given
a 9.4 mL/min flow rate and 9.1 wt % catalyst loading at 300
°C, was found within Cd- and Zn-modified NU-1000 after a
run time of ∼39 and ∼43 h, respectively. Maximum
propadiene yields just prior to the end of the temperature
sweep at 250 °C came from Cd-, Zn-, as well as Co-loaded
MOFs (Figure 2). These metals were found to rise significantly
beyond the diene yield of bare NU-1000, which is likely giving
a small background isomerization due to either Zr interaction
or thermodynamic equilibrium. Increasing the reaction
temperature to 300 °C showed further increases in propadiene
yield for Co, Fe, Zn, and In. It should be noted, however, that
the Co-AIM selectivity to propadiene at 300 °C is comparable
to that of the unmodified NU-1000 (Figure S2). A small drop
in conversion for Cd from 250 to 300 °C coincides with an
increase (albeit small) in acetylene production, which may
indicate either a degradation in the MOF structure or cluster
sintering when heating up to 300 °C.
While many of the metals tested catalyze the isomerization
of propyne to propadiene, Cd and Zn were found to be the
most effective. The efficacy of Cd- and Zn-modified NU-1000
for isomerization compared to the other catalysts may be due
to the basic character of the metal oxide sites and their ability
to instigate a 1,3-hydrogen shift for alkynes,43 assuming the
mechanism is similar across most AIMs. Previous isomer-
ization literature has shown basic metal oxides to abstract and
shuttle the methyl H to the terminal alkyne in accordance with
their basicity.8,44 Calculations discussed later point to this
mechanism in the Zn-AIM. It should be noted that
isomerization occurs in the absence of hydrogen as well.
Preliminary experiments with Co, Cu, Cd, In, and Zn AIMs
without H2 and at low propyne conversions (<20%) show up
to 100% selectivity to the isomer from 50 to 250 °C, as there
are few competing mechanisms other than oligomerization.
Obviously, these conditions yield no hydrogenation products.
Selective partial hydrogenation to propylene was also
observed to varying extents (Figures S3−S4). The Cu-
modified NU-1000 overwhelmingly produced more propylene
than any other AIM (98.3% yield, 98.3% selectivity). This is
unsurprising, however, as Cu has been well-known to catalyze
the selective hydrogenation of propyne to propylene.45 The
Cu-AIM, however, compares favorably in yield and selectivity
to other Cu catalysts (e.g., Cu@SiO2) from the literature.45,46
The only active metal catalysts for propylene above 250 °C
were Zn, Co, and Ni. Propylene selectivity decreased upon
metalation for almost all other AIM catalysts compared to bare
NU-1000. It should be noted that conversion of propyne for all
metal catalysts under these conditions either remained around
the same level as NU-1000 or rose above the bare MOF when
T ≥ 200 °C.
Full hydrogenation to propane was most prevalent in Zn-
containing NU-1000 (Figures S5−S6), although the Zn-AIM
exhibits the highest propyne conversion at lower temperatures
when compared to other catalysts. At 150 °C, for example, Zn-
AIM exhibited 12.5% propyne conversion compared to the
6.1% conversion for NU-1000. A decrease in propane yield
from single exposures of metal precursors to double exposures
results in a drop in propane yield (see Zn−Zn- and Mn−Mn-
modified NU-1000 in Figure S5), even though propyne
conversions did not change significantly. It is possible an
increase in metal sites decreases the propensity for full
hydrogenation while increasing the propensity for another
reaction, such as partial hydrogenation or isomerization. An
increase in the isomerization reaction can be seen in Mn−Mn,
whereas Zn−Zn results in a small increase in partial
hydrogenation when compared their single-dose counterparts.
To understand the difference in selectivity between different
metal ions, computations were performed on the two extreme
cases, namely, Zn2+ and Cu2+ deposited catalysts, that show the
highest and the lowest selectivity, respectively, for isomer-
ization among the first-row transition metals at 300 °C. These
metals were also chosen as comparative models for hydro-
genation due to their difference in performance. A single metal
atom model was used despite characterization showing
multiple metal atoms due to the preference metal ions have
to occupy different faces of the Zr node in computational
models, as highlighted in Li et al.19
First, the mechanism for hydrogenation would involve the
splitting of the H2 being flown over the catalyst. Different
metal ions could promote either homolytic or heterolytic
splitting of H2 (Figure 3) and thus might have different
mechanisms for the reaction. Table 2 shows the computed
reaction enthalpies and free energies per H2 molecule for the
two different reactions.
While in the heterolytic splitting reaction 1 the oxidation
state of the metal does not change, in reaction 2, the addition
of a hydrogen atom arising from the homolytic splitting leads
to a reduction of the metal from a +II oxidation state to +I as
the electron is accepted by the metal ion and the proton bonds
D
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
Previous proposed mechanisms for hydrogenation of
unsaturated hydrocarbons on AIM catalysts deposited in
NU-1000 were based on a heterolytic splitting of H2 with the
formation of a metal hydride (H1) as shown in Scheme 1.19
This is obtained by heterolytic splitting of a hydrogen molecule
over the dehydrated catalyst structure shown in Figure 3.
The adsorption of propyne is followed by the transfer of the
hydride to the terminal carbon forming a metal−carbon bond
(H3A/B). The hydride can then either transfer to the β-carbon
and the metal can form a bond with the terminal carbon (path
A) or the other way around (path B). Another hydrogen
molecule then adsorbs on the metal (H4A/B) and splits
heterolytically forming back the metal hydride, while the
proton attacks the β-carbon to form propene (H5). The
relative Gibbs free energies for this hydrogenation mechanism
for both Cu and Zn are reported in Table 3. The Gibbs free
Figure 3. Reaction scheme for two possible hydrogen splitting
pathways as reaction 1 and reaction 2.
Table 2. Reaction Enthalpies and Gibbs Free Energies (in
Parentheses) Per Hydrogen Molecule (kcal/mol) for
Dissociation over Cu and Zn as Calculated Per the Scheme
Shown in Figure 3
Metal
Reaction 1
Reaction 2
Cu
Zn
−15.9 (1.6)
−20.1 (−5.2)
−72.4 (−51.2)
24.3 (34.6)
Table 3. Relative Gibbs Free Energies (kcal/mol)
Calculated at 300 °C for Both Hydrogenation Pathways
Shown in Figure 5 for Cu and Zn
to the μ-oxo. Whereas Cu prefers the +I oxidation state with
the d10 electron configuration, Zn has the stable d10
configuration in the + II oxidation state. This is reflected in
the reaction energies in Table 2. This suggests the resting state
of the Cu catalysts will more likely have the copper in the more
stable +1 oxidation state under H2. In contrast, for Zn2+,
heterolytic H2 splitting is energetically much more favorable.
Throughout the reaction pathways for Zn, the overall spin state
remains a singlet while for the Cu, the doublet and singlet spin
states are considered, respectively, for intermediates with
formal Cu2+ and Cu1+ oxidation states.
TS-
TS-
H1
0.0
H2
9.1
23A/B
H3A/B H4A/B 45A/B
H5
Cu (path
A)
Cu (path
B)
Zn (path
A)
Zn (path
B)
18.7
23.2
41.1
38.0
−17.8
−17.2
−12.3
−15.3
−7.8
−7.2
−3.0
−3.0
14.1
13.5
32.5
30.4
−11.9
0.0
0.0
0.0
9.1
12.3
12.3
−11.9
−13.3
−13.3
Thermogravimetric analysis (TGA) of the catalysts
suggested presence of water in the system for the Zn catalyst
around this temperature (Figures S7−S11). The model thus
includes one water molecule bound to Zn that is involved in
the mechanism for isomerization. However, the water molecule
does not bind to the zinc hydride and is thus not included in
hydrogenation. Optimized structures of clusters with water
bound to the bare metal and to the metal hydride, albeit
weakly, are shown in Figure S12 Neither the hydrogenation
nor isomerization mechanism proposed for Cu involves this
water molecule as the TGA of the Cu catalyst showed the last
peak at around 230 °C, which is approximately when the
catalyst starts to exhibit the higher selectivity toward
hydrogenation.
energy barrier for Cu (path A) is 36.6 kcal/mol, and that for
Zn (pathway B) is 53.3 kcal/mol (see Figure S13). A possible
rationale for TS23 in pathways A and B having different
relative energies is the extent to which the C−C−C bond angle
in propyne deviates from the 180° starting point. As seen in
Figure S27, the TS23A undergoes smaller distortion in Cu
while for the Zn catalyst, the TS23B has a smaller bending of
the angle compared to that of their other counterpart.
In the hydrogenation mechanism proposed in Scheme 1, the
formal oxidation state of the metal does not change as the
hydrogen splits heterolytically. The hydrogenation mechanism
involving homolytic splitting of H2 through which the reaction
may undergo for Cu is shown in Scheme 2.
Scheme 1. Reaction Mechanism for Hydrogenation Involving the Heterolytic Splitting of Dihydrogen
E
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
a
Scheme 2. Reaction Mechanism for Hydrogenation Involving the Homolytic Splitting of Dihydrogen
a
The relative free energies in kcal/mol calculated for reactions over Cu are noted along with the intermediates.
Scheme 3. Isomerization Mechanisms Involving Zn2+ (Left) and Cu1+ (Right) along with Their Respective Relative Free
Energies (kcal/mol) Calculated at 300 °C
The first addition of the hydrogen atom to H’2 leads to the
reduction of copper (H’3) as it accepts the incoming electron
while the proton bonds to the μ-oxo. The subsequent addition
of the other hydrogen atom on the adsorbed propyne results in
the formation of a metal−carbon bond. This changes the
formal oxidation state of the metal to +II in the intermediate
H’4A/B. Like in Scheme 1, both possibilities of the metal−
carbon in H’4A/B were studied as paths A and B. The
hydrogenation process is then completed as the proton of the
μ-hydroxy is abstracted (TS-45) to form propene. The relative
free energies for both the pathways are noted alongside each
intermediate in Scheme 2. The Gibbs free energy barrier is
31.3 kcal/mol for the hydrogenation showing that this pathway
is preferred over the one involving heterolytic splitting of H2.
The isomerization mechanism for Zn in Scheme 3 involve a
heterolytic splitting of a water molecule over Zn forming a
metal-hydroxy bond. The hydroxy group then acts as a shuttle
for the proton between the methyl group and the terminal
carbon for the 1,3-hydrogen shift. The Gibbs free energy
barrier for Zn in this mechanism was found to be 34.2 kcal/
mol. When compared to the free energy of activation for
hydrogenation, which is 53.3 kcal/mol, this explains the
selectivity of Zn toward the isomerization product. This
mechanism was also studied for Cu2+ (see SI for details). But
as previously established, the Cu catalyst will have the Cu in a
+ I oxidation state and thus a mechanism involving Cu+ must
be considered here.
This mechanism for isomerization does not cycle through
the + I/+II oxidation state of the Cu. This is along similar lines
as the mechanism reported for Zn. But since there is no
heterolytic splitting of water over the metal ion, the mechanism
goes through opening of the metal ion− terminal hydroxy
bond. This hydroxy group then acts as the shuttle for the
proton. Unlike the previous isomerization mechanism
however, this migration is stepwise. The hydroxy shuttles the
proton only between the α and the β carbons. The product is
formed after a 2,3-hydrogen shift which is the rate determining
step of the reaction. The reaction energies reported in Scheme
3 show the free energy of activation to be 52.1 kcal/mol for the
isomerization over a Cu+ species.
To identify synergistic effects between multiple proximal
catalytic metal sites, as well as determine the effect of reaction
conditions, variable pressure and time studies were conducted
on Co and Zn bimetallic combinations. In the pressure studies,
F
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
Figure 4. Propadiene yield (A) and selectivity (B) for Co- and Zn-modified MOFs as a function of reaction pressure.
Figure 5. Propylene yield (A) and selectivity (B) for Co- and Zn-modified MOFs as a function of reaction vessel pressure.
the incorporation of Co into Zn-modified NU-1000 showed
high yields and selectivity toward propadiene compared to
monometallic Co-modified NU-1000. The Co−Zn and Zn−
Co MOFs also exhibited low propylene yields and selectivity
compared to the standalone Co-AIM (Figures 4 and 5). These
bimetallic modified MOFs also exhibited lower propane yields,
compared to those of the standalone Zn-AIM (Figure S6), as
well as decreased either the extent of coking or the production
of other unidentified products compared to the Co-AIM (see
carbon balance in SI). These results suggest a synergistic effect
for the isomerization of propyne by Co- and Zn-modified NU-
1000 where the creation of side products (propylene, propane,
coke) is mitigated through bimetallic sites that inhibit the
hydrogenation and coking pathways. Increasing the reaction
pressure beyond 5 atm does, however, result in a slight
decrease in propadiene yield and selectivity while increasing
the yield and selectivity of propylene and propane. It is
possible that an abundance of hydrogen shifts the equilibrium
away from isomerization and toward hydrogenation if the
metal oxide cannot effectively shuttle H from the methyl group
to the terminal alkyne. Additionally, this does not appear to
influence the extent of coking via changes in reaction pressure,
if there is any coking at all. This may be due to the coking
mechanism being dependent on the formation of radicals.47
The difference in propadiene yield between Zn−Co- and Co−
Zn-modified NU-1000 may be due to which metal atoms
occupy the exterior of the cluster, as the amount of Co and Zn
atoms is approximately the same for both MOFs (Figure S14
for ICP data). The AIM with secondary exposure to Zn (i.e.,
Co−Zn MOF) has a higher propadiene yield and selectivity,
which coincides with the high propadiene activity of the
standalone Zn-modified MOF.
Co- and Zn-MOFs were also monitored for ∼24 h at various
temperatures to evaluate deactivation and overall changes in
catalytic behavior (Figures S15, S16). For conversion to
propadiene, many of the Co-containing MOFs (i.e., Co−Co at
250 °C and Co at 300 °C) showed an increase in activity and
selectivity as the reaction progressed toward 24 h, indicative of
an induction period. The induction period is likely due to the
reduction of Co by the hydrogen feed gas at the beginning of
the reaction. By contrast, a slight deactivation can be seen well
after 16 h in some Zn-containing MOFs, most noticeably with
Zn−Co at 250 °C and Zn−Zn at 250 °C catalysts. The
deactivation does not appear to be due to blocking of the
active Zn sites by coke, however, as the carbon balance stays
relatively the same and high throughout the experiment
(Figures S17−S19). Zn and Co−Zn MOFs at 300 °C required
little to no induction period nor deactivation while providing
sizable yields and high selectivity, and thus appear to be the
most effective catalysts for propyne isomerization to
propadiene.
Powder XRD of the Zn and Co bimetallic combinations
show the crystalline structure of NU-1000 remains intact for
Zn−Co, Co−Zn, and Zn−Zn samples, while Co−Co appears
G
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
to lose its ordered crystalline structure after deposition (Figure
S20). The ICP-derived loading of Co−Co is consistent with
degradation of the MOF framework, as the number of Co
metal atoms per Zr6 node (>20 atoms) was measured to be
much larger than what is controllably achieved (Figure S14).
Other AIM-modified MOFs exhibited <7 metal atoms on each
node, as previously observed for well-controlled reactions with
NU-1000 nodes. It is possible that a collapse in MOF structure
occurs during the second exposure of NU-1000 to the Co
precursor. This change in structure may also be responsible for
the significant decrease in propyne conversion between single
and double exposure Co AIMs (Figure S21). It is unclear as to
why double Co precursor exposures causes a degradation in
structure, although follow-up experiments are planned.
United States; orcid.org/0000-0001-5227-1396;
Email: gagliard@umn.edu
Alex B. F. Martinson − Materials Science Division, Argonne
National Laboratory, Lemont, Illinois 60439, United States;
orcid.org/0000-0003-3916-1672; Email: martinson@
anl.gov
Massimiliano Delferro − Chemical Sciences and Engineering
Division, Argonne National Laboratory, Lemont, Illinois
60439, United States; orcid.org/0000-0002-4443-165X;
Email: delferro@anl.gov
Authors
Ryan A. Hackler − Chemical Sciences and Engineering
Division, Argonne National Laboratory, Lemont, Illinois
60439, United States; orcid.org/0000-0003-4698-6074
Riddhish Pandharkar − Department of Chemistry, Chemical
Theory Center, and Supercomputing Institute, University of
Minnesota-Twin Cities, Minneapolis, Minnesota 55455,
United States
Magali S. Ferrandon − Chemical Sciences and Engineering
Division, Argonne National Laboratory, Lemont, Illinois
60439, United States
In Soo Kim − Materials Science Division, Argonne National
Laboratory, Lemont, Illinois 60439, United States;
Nanophotonics Research Center, Korea Institute of Science
and Technology (KIST), Seoul 02792, Republic of Korea
Nicolaas A. Vermeulen − Department of Chemistry,
Northwestern University, Evanston, Illinois 60208, United
States
Leighanne C. Gallington − X-ray Science Division, Argonne
National Laboratory, Lemont, Illinois 60439, United States;
orcid.org/0000-0002-0383-7522
Karena W. Chapman − Department of Chemistry, Stony
Brook University, Stony Brook, New York 11764, United
States; orcid.org/0000-0002-8725-5633
Omar K. Farha − Department of Chemistry, Northwestern
University, Evanston, Illinois 60208, United States;
orcid.org/0000-0002-9904-9845
Christopher J. Cramer − Department of Chemistry, Chemical
Theory Center, and Supercomputing Institute, University of
Minnesota-Twin Cities, Minneapolis, Minnesota 55455,
United States; orcid.org/0000-0001-5048-1859
CONCLUSIONS
■
The survey of metalations for MOFs conducted herein show
multiple avenues for biasing a reaction system toward a certain
product while also allowing for a reduction in undesirable
products through synergistic effects. Certain metals, such as
Zn, Cd, and In, exhibited a high selectivity toward the propyne
isomer under H2 while showing a smaller affinity toward partial
hydrogenation and no oligomerization. Other metals, such as
Cu and Co, showed a larger affinity toward partial hydro-
genation. While full hydrogenation was limited for all metals,
further reductions in propane production were found with
particular metal combinations. For example, a combination of
Co with Zn resulted in a reduction of propane across all
experimental parameters surveyed when compared to the
standalone metals with as much as a 78% reduction in propane
yield. The incorporation of Zn into Co-AIMs also reduced
coking and oligomerization: undesirable side reactions that can
reduce the efficacy of alkyne and alkene transformation
catalysts. The preference for isomerization vs partial hydro-
genation in the case of Zn and Cu lies in their respective
preferences for heterolytic vs homolytic H2 cleavage and H
shuttling mechanism between 1,3- or 2,3-hydrogen shift, with
the latter being more costly energetically. Isomerization was
found to be more energetically favorable than partial
hydrogenation in Zn-AIM by 19.1 kcal/mol, whereas partial
hydrogenation was more favorable in Cu-AIM when compared
to isomerization by 20.8 kcal/mol. These results highlight the
potential for high-throughput testing and extensive metal
surveying when looking at solutions for extensive reaction
systems.
Complete contact information is available at:
https://pubs.acs.org/10.1021/jacs.0c08641
Author Contributions
$These authors contributed equally
ASSOCIATED CONTENT
■
sı
* Supporting Information
Notes
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/jacs.0c08641.
The authors declare no competing financial interest.
Synthesis and characterization of Zn-AIM, Co-AIM, Cd-
AIM, Cu-AIM, Fe-AIM, Ga-AIM, Mn-AIM, Mo-AIM,
Ni-AIM, Sn-AIM, W-AIM, In-AIM, and Al-AIM (PDF)
ACKNOWLEDGMENTS
■
This work was supported as part of the Inorganometallic
Catalyst Design Center, an Energy Frontier Research Center
funded by the U.S. Department of Energy, Office of Science,
Basic Energy Sciences under Award No. DE-SC0012702. J.S.
acknowledges support by Deutsche Forschungsgemeinschaft
(DFG, German Research Foundation) within project
430942176. This work also used the Advanced Photon Source,
a U.S. Department of Energy (DOE) Office of Science User
Facility operated for the DOE Office of Science by Argonne
National Laboratory under Contract No. DE-AC02-
06CH11357.
AUTHOR INFORMATION
Corresponding Authors
■
Joachim Sauer − Institut für Chemie, Humboldt-Universität
zu Berlin, 10099 Berlin, Germany; orcid.org/0000-0001-
6798-6212; Email: js@chemie.hu-berlin.de
Laura Gagliardi − Department of Chemistry, Chemical Theory
Center, and Supercomputing Institute, University of
Minnesota-Twin Cities, Minneapolis, Minnesota 55455,
H
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
K. Sintering-Resistant Single-Site Nickel Catalyst Supported by Metal-
Organic Framework. J. Am. Chem. Soc. 2016, 138 (6), 1977−82.
(20) Li, Z. Y.; Peters, A. W.; Bernales, V.; Ortuno, M. A.; Schweitzer,
N. M.; DeStefano, M. R.; Gallington, L. C.; Platero-Prats, A. E.;
Chapman, K. W.; Cramer, C. J.; Gagliardi, L.; Hupp, J. T.; Farha, O.
K. Metal-Organic Framework Supported Cobalt Catalysts for the
Oxidative Dehydrogenation of Propane at Low Temperature. ACS
Cent. Sci. 2017, 3 (1), 31−38.
(21) Rimoldi, M.; Bernales, V.; Borycz, J.; Vjunov, A.; Gallington, L.
C.; Platero-Prats, A. E.; Kim, I. S.; Fulton, J. L.; Martinson, A. B. F.;
Lercher, J. A.; Chapman, K. W.; Cramer, C. J.; Gagliardi, L.; Hupp, J.
T.; Farha, O. K. Atomic Layer Deposition in a Metal-Organic
Framework: Synthesis, Characterization, and Performance of a Solid
Acid. Chem. Mater. 2017, 29 (3), 1058−1068.
(22) Peters, A. W.; Li, Z.; Farha, O. K.; Hupp, J. T. Atomically
Precise Growth of Catalytically Active Cobalt Sulfide on Flat Surfaces
and within a Metal-Organic Framework via Atomic Layer Deposition.
ACS Nano 2015, 9, 8484−8490.
(23) Zhang, X.; Huang, Z.; Ferrandon, M.; Yang, D.; Robison, L.; Li,
P.; Wang, T. C.; Delferro, M.; Farha, O. K. Catalytic Chemoselective
Functionalization of Methane in a Metal-Organic Framework. Nat.
Catal. 2018, 1, 356−362.
(24) Platero-Prats, A. E.; Li, Z.; Gallington, L. C.; Peters, A. W.;
Hupp, J. T.; Farha, O. K.; Chapman, K. W. Addressing the
characterisation challenge to understand catalysis in MOFs: the case
of nanoscale Cu supported in NU-1000. Faraday Discuss. 2017, 201,
337−350.
(25) Kim, I. S.; Ahn, S.; Vermeulen, N. A.; Webber, T. E.;
Gallington, L. C.; Chapman, K. W.; Penn, R. L.; Hupp, J. T.; Farha,
O. K.; Notestein, J. M.; Martinson, A. B. F. The Synthesis Science of
Targeted Vapor-Phase Metal-Organic Framework Postmodification. J.
Am. Chem. Soc. 2020, 142 (1), 242−250.
(26) Kim, I. S.; Borycz, J.; Platero-Prats, A. E.; Tussupbayev, S.;
Wang, T. C.; Farha, O. K.; Hupp, J. T.; Gagliardi, L.; Chapman, K.
W.; Cramer, C. J.; Martinson, A. B. F. Targeted Single-Site MOF
Node Modification: Trivalent Metal Loading via Atomic Layer
Deposition. Chem. Mater. 2015, 27 (13), 4772−4778.
REFERENCES
■
(1) Burch, R.; Hayes, M. J. C-H bond activation in hydrocarbon
oxidation on solid catalysts. J. Mol. Catal. A: Chem. 1995, 100 (1−3),
13−33.
(2) Zaera, F. Surface chemistry of hydrocarbon fragments on
transition metals: towards understanding catalytic processes. Catal.
Lett. 2003, 91 (1−2), 1−10.
(3) Studt, F.; Abild-Pedersen, F.; Bligaard, T.; Sorensen, R. Z.;
Christensen, C. H.; Norskov, J. K. Identification of non-precious
metal alloy catalysts for selective hydrogenation of acetylene. Science
2008, 320 (5881), 1320−1322.
(4) Tysoe, W. T.; Nyberg, G. L.; Lambert, R. M. Low-Temperature
Catalytic Chemistry of the Pd(111) Surface - Benzene and Ethylene
from Acetylene. J. Chem. Soc., Chem. Commun. 1983, No. 11, 623−
625.
(5) Molnar, A.; Sarkany, A.; Varga, M. Hydrogenation of carbon-
carbon multiple bonds: chemo-, regio- and stereo-selectivity. J. Mol.
Catal. A: Chem. 2001, 173 (1−2), 185−221.
(6) Hoffmann-Roder, A.; Krause, N. Synthesis and properties of
allenic natural products and pharmaceuticals. Angew. Chem., Int. Ed.
2004, 43 (10), 1196−216.
(7) Zimmer, R.; Dinesh, C. U.; Nandanan, E.; Khan, F. A.
Palladium-catalyzed reactions of allenes. Chem. Rev. 2000, 100 (8),
3067−126.
(8) Hashmi, A. S. K., Synthesis of Allenes by Isomerization
Reactions. In Modern Allene Chemistry, Krause, N.; Hashmi, A. S. K.,
Eds. Wiley-VCH Verlag GmbH & Co: 2004.
(9) Parmentier, J. H.; Peer, H. G.; Schutte, L. The Isomerization of
Propyne into Propadiene Over a Silica Catalyst. J. Catal. 1971, 22,
213−218.
(10) Vermeulen, N. A.; Karagiaridi, O.; Sarjeant, A. A.; Stern, C. L.;
Hupp, J. T.; Farha, O. K.; Stoddart, J. F. Aromatizing olefin metathesis
by ligand isolation inside a metal-organic framework. J. Am. Chem. Soc.
2013, 135 (40), 14916−14919.
(11) Syed, Z. H.; Sha, F.; Zhang, X.; Kaphan, D. M.; Delferro, M.;
Farha, O. K. Metal-Organic Framework Nodes as a Supporting
Platform for Tailoring the Activity of Metal Catalysts. ACS Catal.
2020, 10, 11556.
(27) Lownsbury, J. M.; Gladden, J. A.; Campbell, C. T.; Kim, I. S.;
Martinson, A. B. F. Direct Measurements of Half-Cycle Reaction
Heats during Atomic Layer Deposition by Calorimetry. Chem. Mater.
2017, 29 (20), 8566−8577.
(12) Cui, Y. J.; Li, B.; He, H. J.; Zhou, W.; Chen, B. L.; Qian, G. D.
Metal-Organic Frameworks as Platforms for Functional Materials. Acc.
Chem. Res. 2016, 49 (3), 483−493.
(28) Toby, B. H.; Von Dreele, R. B. GSAS-II: the genesis of a
modern open-source all purpose crystallography software package. J.
Appl. Crystallogr. 2013, 46 (2), 544−549.
(13) Lee, J.; Farha, O. K.; Roberts, J.; Scheidt, K. A.; Nguyen, S. T.;
Hupp, J. T. Metal-organic framework materials as catalysts. Chem. Soc.
Rev. 2009, 38 (5), 1450−1459.
̌
̌
̌
(29) Petrícek, V.; Dusek, M.; Palatinus, L. Z. Crystallographic
Computing System JANA2006: General features. Z. Kristallogr. -
Cryst. Mater. 2014, 229, 345−352.
(14) Liu, L.; Corma, A. Metal Catalysts for Heterogeneous Catalysis:
From Single Atoms to Nanoclusters and Nanoparticles. Chem. Rev.
2018, 118 (10), 4981−5079.
(30) Yakovenko, A. A.; Reibenspies, J. H.; Bhuvanesh, N.; Zhou, H.-
C. Generation and applications of structure envelopes for porous
metal-organic frameworks. J. Appl. Crystallogr. 2013, 46 (2), 346−353.
(31) McCusker, L. B.; Baerlocher, C. Using electron microscopy to
complement X-ray powder diffraction data to solve complex crystal
structures. Chem. Commun. 2009, 1439−1451.
(15) Deria, P.; Mondloch, J. E.; Tylianakis, E.; Ghosh, P.; Bury, W.;
Snurr, R. Q.; Hupp, J. T.; Farha, O. K. Perfluoroalkane
Functionalization of NU-1000 via Solvent-Assisted Ligand Incorpo-
ration: Synthesis and CO2 Adsoprtion Studies. J. Am. Chem. Soc.
2013, 135, 16801−16804.
(16) Mondloch, J. E.; Bury, W.; Fairen-Jimenez, D.; Kwon, S.;
DeMarco, E. J.; Weston, M. H.; Sarjeant, A. A.; Nguyen, S. T.; Stair,
P. C.; Snurr, R. Q.; Farha, O. K.; Hupp, J. T. Vapor-phase metalation
by atomic layer deposition in a metal-organic framework. J. Am. Chem.
Soc. 2013, 135 (28), 10294−10297.
(17) George, S. M. Atomic layer deposition: an overview. Chem. Rev.
2010, 110 (1), 111−31.
(18) Kim, I. S.; Li, Z.; Zheng, J.; Platero-Prats, A. E.; Mavrandonakis,
A.; Pellizzeri, S.; Ferrandon, M.; Vjunov, A.; Gallington, L. C.;
Webber, T. E.; Vermeulen, N. A.; Penn, R. L.; Getman, R. B.; Cramer,
C. J.; Chapman, K. W.; Camaioni, D. M.; Fulton, J. L.; Lercher, J. A.;
Farha, O. K.; Hupp, J. T.; Martinson, A. B. F. Sinter-Resistant
Platinum Catalyst Supported by Metal-Organic Framework. Angew.
Chem., Int. Ed. 2018, 57 (4), 909−913.
(19) Li, Z.; Schweitzer, N. M.; League, A. B.; Bernales, V.; Peters, A.
W.; Getsoian, A. B.; Wang, T. C.; Miller, J. T.; Vjunov, A.; Fulton, J.
L.; Lercher, J. A.; Cramer, C. J.; Gagliardi, L.; Hupp, J. T.; Farha, O.
(32) Yakovenko, A. A.; Wei, Z.; Wriedt, M.; Li, J.-R.; Halder, G. J.;
Zhou, H.-C. Study of guest molecules in metal-organic frameworks by
powder X-ray diffraction: analysis of difference envelope density.
Cryst. Growth Des. 2014, 14, 5397−5407.
(33) Gallington, L. C.; Kim, I. S.; Liu, W. G.; Yakovenko, A. A.;
Platero-Prats, A. E.; Li, Z.; Wang, T. C.; Hupp, J. T.; Farha, O. K.;
Truhlar, D. G.; Martinson, A. B. F.; Chapman, K. W. Regioselective
Atomic Layer Deposition in Metal-Organic Frameworks Directed by
Dispersion Interactions. J. Am. Chem. Soc. 2016, 138 (41), 13513−
13516.
(34) Zhao, Y.; Truhlar, D. G. A new local density functional for
main-group thermochemistry, transition metal bonding, thermochem-
ical kinetics, and noncovalent interactions. J. Chem. Phys. 2006, 125
(19), 194101.
(35) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
I
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX

Journal of the American Chemical Society
pubs.acs.org/JACS
Article
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonneberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.;
Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.;
Montgomery, J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd,
J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.;
Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S.
S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J.
E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.;
Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.;
Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A.
D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.
Gaussian 09, Revision B.01. Gaussian 09, Revision B.01, Gaussian,
Inc., Wallingford CT, 2009.
(36) Weigend, F.; Ahlrichs, R. Balanced basis sets of split valence,
triple zeta valence and quadruple zeta valence quality for H to Rn:
Design and assessment of accuracy. Phys. Chem. Chem. Phys. 2005, 7
(18), 3297−305.
̈
(37) Andrae, D.; Haußermann, U.; Dolg, M.; Stoll, H.; Preuß, H.
Energy-adjusted ab initio pseudopotentials for the second and third
row transition elements. Theoretica Chimica Acta 1990, 77, 123−141.
(38) Zhao, Y.; Truhlar, D. G. The M06 suite of density functionals
for main group thermochemistry, thermochemical kinetics, non-
covalent interactions, excited states, and transition elements: two new
functionals and systematic testing of four M06-class functionals and
12 other function. Theor. Chem. Acc. 2008, 120 (1−3), 215−241.
(39) Becke, A. D. Density-functional thermochemistry. III. The role
of exact exchange. J. Chem. Phys. 1993, 98 (7), 5648−5652.
(40) Grimme, S.; Ehrlich, S.; Goerigk, L. Effect of the damping
function in dispersion corrected density functional theory. J. Comput.
Chem. 2011, 32 (7), 1456−1465.
(41) Zhao, Y.; Truhlar, D. G. A new local density functional for
main-group thermochemistry, transition metal bonding, thermochem-
ical kinetics, and noncovalent interactions. J. Chem. Phys. 2006, 125
(19), 194101−194101.
(42) Planas, N.; Mondloch, J. E.; Tussupbayev, S.; Borycz, J.;
Gagliardi, L.; Hupp, J. T.; Farha, O. K.; Cramer, C. J. Defining the
Proton Tpology of the Zr6-Based Metal-Organic Framework NU-
1000. J. Phys. Chem. Lett. 2014, 5, 3716−3723.
(43) Vitkovskaya, N. M.; Kobychev, V. B.; Trofimov, A. B.;
Trofimov, B. A. Multiple bond migration with participation of a
protophilic agent 1. An ab initio quantum-chemical study of 1,3-
hydrogen shift in propene and propyne with participation of
hydroxide ion. Russ. Chem. Bull. 1997, 46, 1677−1682.
(44) Hackler, L.; Konya, Z.; Kiricsi, I. Transformation of propyne to
propadiene over various solid catalysts of different acid-base character.
React. Kinet. Catal. Lett. 2001, 74 (2), 363−370.
(45) Bridier, B.; Lopez, N.; Perez-Ramirez, J. Partial hydrogenation
of propyne over copper-based catalysts and comparison with nickel-
based analogues. J. Catal. 2010, 269 (1), 80−92.
(46) Wehrli, J.T.; Thomas, D.J.; Wainwright, M.S.; Trimm, D.L.;
Cant, N.W. Selective Hydrogenation of Propyne over an Ion-
Exchanged Copper on Silica Catalyst. Appl. Catal. 1990, 66 (1),
199−208.
(47) Wauters, S.; Marin, G. B. Kinetic Modeling of Coke Formation
during Steam Cracking. Ind. Eng. Chem. Res. 2002, 41, 2379−2391.
J
https://dx.doi.org/10.1021/jacs.0c08641
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX