supplementary materials for · 1/10/2020 · acetate (0.1 m), followed by stirring at 80 °c for 4...
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science.sciencemag.org/content/367/6474/193/suppl/DC1
Supplementary Materials for
Hydrophobic zeolite modification for in situ peroxide formation
in methane oxidation to methanol
Zhu Jin, Liang Wang*, Erik Zuidema, Kartick Mondal, Ming Zhang, Jian Zhang,
Chengtao Wang, Xiangju Meng, Hengquan Yang, Carl Mesters, Feng-Shou Xiao*
*Corresponding author. Email: [email protected] (L.W.); [email protected] (F.-S.X.)
Published 10 January 2020, Science 367, 193 (2020)
DOI: 10.1126/science.aaw1108
This PDF file includes:
Materials and Methods
Figs. S1 to S51
Tables S1 to S7
References
1
Materials and Methods
Materials. All reagents were commercially obtained without purification. Tetraethyl orthosilicate
(TEOS), sodium borohydride, ammonium acetate, ethanol, methanol and polyvinyl pyrrolidone
(PVP) were obtained from the Aladdin Chemical Reagent Company. Tetrapropylammonium
hydroxide (TPAOH, ca. 12.6 %) and boehmite (AlOOH) were supplied by Changling Catalyst
Company. Sodium hydroxide and acetone were obtained from Sinopharm Chemical Reagent Co.,
Ltd. Ammonia solution (25-28 %) was obtained from Shanghai Lingfeng Chemical Reagent Co.,
Ltd. Hexadecyltrimethoxysilane, trimethoxyphenylsilane, trimethoxy(propyl)silane, and 3,3,3-
(trifluoromethyl)trimethoxysilane were obtained from Aladdin Chemical Reagent Company.
Chlorauric acid and palladium chloride were obtained from Zhejiang Metallurgical Research
Institute.
Synthesis of AuPd@SiO2. As a typical run for the synthesis bimetallic Au-Pd nanoparticle colloid,
1.111 g of PVP was dissolved within 100 mL of aqueous HAuCl4 and Na2PdCl4 solution (molar
ratio of Au and Pd at 1:1, containing 32.46 mg of Au, 17.53 mg of Pd) at 0 °C and stirred for 0.5 h.
Then, 10 mL of newly made NaBH4 (0.1 M) aqueous solution was added. After stirring for another
2 h, the bimetallic AuPd nanoparticle colloid was dialyzed for 2 days to remove Na+ and Cl- ions.
To synthesize SiO2 encapsulated bimetallic AuPd nanoparticles (AuPd@SiO2), 80 mL of
ethanol and 6 mL of ammonia solution were added into the as-prepared AuPd nanoparticle colloid
under stirring for 0.5 h. Then, 3.47 g of TEOS was added into the mixture and stirred at room
temperature for 8 h. The mixture was distilled under vacuum to remove the solvent at 60 °C and
dried at 100 °C for 12 h to obtain the AuPd@SiO2 sample.
Synthesis of AuPd@ZSM-5. The ZSM-5 fixed AuPd nanoparticles were synthesized under solvent-
free conditions using as-synthesized 1 g of AuPd@SiO2, 0.027 g of boehmite, and 0.833 g of
TPAOH (40 wt%) as raw materials. After grinding the raw materials in mortar for 10 minutes, the
mixture was transferred into an autoclave to crystallize at 180 °C for 3 days. After washing with
distilled water for several times at room temperature, drying at 100 °C and calcining at 550 °C for
4 h, the AuPd@ZSM-5 with atomic Si/Al ratio at 30 was finally obtained. The other samples with
different Si/Al ratio was synthesized by changing the amount of boehmite in the precursors. If there
is no special notification, the AuPd@ZSM-5 is the sample with Si/Al ratio at 30.
Synthesis of AuPd@ZSM-5-R. The AuPd@ZSM-5-R zeolite crystals were synthesized by a post-
silylation method. As a typical run for the synthesis of AuPd@ZSM-5-C16, 0.5 g of the
AuPd@ZSM-5 was dried at 150 °C under vacuum and then dispersed in 10 mL of anhydrous toluene
by sonication at room temperature. Then, 0.433 g of hexadecyltrimethoxysilane was dissolved
within 20 mL of anhydrous toluene and the zeolite suspension was added to the solution under
stirring. The mixture was stirred for 24 h at 500 rpm at room temperature. After filtrating, washing
with ethanol, drying at 100 °C for overnight, the AuPd@ZSM-5-C16 was obtained. The
AuPd@ZSM-5-C3 and -C6 were synthesized according to similar procedures except for using
trimethoxy(propyl)silane (0.496 g) and trimethoxyphenylsilane (0.667 g) as precursors. If there is
no special notification, the AuPd@ZSM-5-R are the samples with Si/Al ratio at 30.
Synthesis of ZSM-5 zeolite. As a typical run, 0.052 g of NaAlO2, 3 mL of TPAOH (40 wt%), and 3.5
2
mL of TEOS were dissolved in 11.28 g of water. After stirring for 30 min at room temperature, the
mixture was transferred into an autoclave and hydrothermally treated at 180 °C for 2 days. After
filtrating, washing with water, and calcining to remove the template at 550 °C for 4 h in air, the Na-
form ZSM-5 zeolite was obtained. An ion-exchange process was performed to obtain the H-form
ZSM-5. Typically, 1 g of Na-form ZSM-5 zeolite was dispersed within in 50 mL of ammonium
acetate (0.1 M), followed by stirring at 80 °C for 4 h. Then the solid powder was collected by
filtrating, washing with water, and drying at 100 °C. The aforementioned ion-exchange procedures
were repeated to obtain the H-form ZSM-5 zeolite.
Synthesis of AuPd/ZSM-5. The AuPd/ZSM-5 was synthesized by traditional impregnation method.
As a typical run, 1 g of ZSM-5 zeolite was added into 5.6 g of aqueous solution containing HAuCl4
(32.46 mg of Au) and Na2PdCl4 (17.53 mg of Pd). Then the mixture was treated under ultrasonic at
room temperature for 1 h, following by grinding the mixture at 70-80 °C to remove the water. The
obtained powder was dried at 100 °C for 6 h and calcined at 400 °C for 3 h in air, the AuPd/ZSM-5
was finally obtained.
Synthesis of AuPd/ZSM-5-R. The AuPd/ZSM-5-R samples were synthesized by the post-silylation
method. The procedures are the same as those in the treatment of AuPd@ZSM-5, excepting for
using AuPd/ZSM-5 as the precursor.
Synthesis of AuPd@SiO2-C16. As a typical run, 0.5 g of the AuPd@SiO2 was dried at 150 °C under
vacuum and then dispersed in 10 mL of anhydrous toluene under sonication at room temperature.
0.433 g of hexadecyltrimethoxysilane was dissolved within 20 mL of anhydrous toluene and the
suspension was added to the liquor under stirring. The mixture was stirred for 24 h at 500 rpm at
room temperature. After filtrating, washing with ethanol, and drying at 100 °C for overnight, the
AuPd@ SiO2-C16 was finally obtained.
Characterizations. X-ray diffraction (XRD) data were collected on a Rigaku D/MAX 2550
diffractometer with Cu Kα (λ=1.5418 Å). The step size was 0.02°, and the scanning speed was
20°/min. Si/Al ratios and the amount of Au and Pd elements were determined by inductively coupled
plasma (ICP) analysis (Perkin-Elmer 3300DV). Nitrogen sorption isotherms were measured using
a Micromeritics ASAP2020 system. Transmission electronmicroscopy (TEM), scanning
transmission electron microscopy (STEM), and energy dispersivespectrometer (EDS) were
performed on a JEM-2100F electron microscopy (JEOL, Japan) with an acceleration voltage of 200
kV. In the STEM and EDS characterizations, the sample was loaded on a Cu mesh with carbon film.
Thermogravimetric curves (TG) were performed on a SDT Q600 Simultaneous DSC-TGA in
flowing air with heating rate of 10 °C/min. FT-IR spectra were recorded with a Bruker Vector 22.
The contact angle of water droplets on the solid surface were measured on an Optical Contact Angle
Meter (SL200KB). The 1H→29Si CP/MAS NMR experiment was performed on a Bruker Avance
III 600 solid-state spectrometer equipped with a magnetic field strength of 14.1 T using a 4 mm
double resonance MAS probe with a spinning rate of 10 kHz. The 1H rf field power for 90° pulse,
contact pulse were 50 kHz, and the 29Si rf field power during contact pulse was 60 kHz. The
spectrum was acquired with a 2 s recycle delay, 2400 scans, and a contact time of 3 ms. Chemical
shift was referenced to kaolinite at -91.5 ppm. The 29Si decoupling MAS NMR experiment was
3
performed on a Bruker Avance III-600 solid-state spectrometer at 119.2 MHz, using a 4 mm double
resonance MAS probe with a spinning rate of 6 kHz, 500 scans, and a recycle delay of 4s. The 29Si
decoupling MAS NMR chemical shifts were referenced to kaolinite (-91.5 ppm). The solution 1H
NMR was recorded on a Bruker Avance-400 spectrometer with a spinning rate of 12kHz, 32 scans,
and a recycle delay of 5 s. Chemical shifts are expressed in ppm using D2O (99%D) as a solvent
and a deuterated chloroform (99.9% D) insert. Typically, 0.6 mL of liquor after reaction was mixed
with 0.1 mL of D2O to prepare a solution for NMR measurement. The signal of protons from the
solvent H2O is much higher than that from the products. Therefore, all 1H NMR spectra were
recorded using a pre-saturation solvent suppression technique to suppress the dominant H2O signal.
The water adsorption isotherms were obtained on 3H-2000PW Multi-station Gravimetry Vapor
Sorption Analyzer using gravimetric comparable to volumetric method, vacuum degree at 2.00
g·cm-3, upper limit of test pressure at 3.169 kPa, constant temperature bath at 25 °C, and water as
adsorbate (M=18).
NMR experiments were performed on a Bruker Ascend-500 spectrometer at a resonance
frequency of 202.63 MHz for 31P, with a 4 mm triple-resonance MAS probe at a spinning rate of 10
kHz. 31P MAS NMR spectra with high power proton decoupling were recorded using a π/2 pulse
length of 4.1 μs and a recycle delay of 30 s. The chemical shift of 31P was referenced to 1 M aqueous
H3PO4. Prior to the adsorption of the probe molecules, the acid samples were placed in glass tubes
and connected to a vacuum line for dehydration. The temperature was gradually increased at a rate
of 1 °C min-1, and the samples were kept at a final temperature of 180 °C and a pressure below 10-
3 Pa over a period of 10 h and were then cooled. After the samples cooled to ambient temperature,
a known amount of trimethylphosphine (TMP) was introduced into the samples. The activated
samples were frozen by liquid N2, followed by elimination of the physisorbed probe molecules by
evacuation at room temperature for 10 min. Finally, the sample tubes were flame-sealed. The
preparation of the TMP adsorbed sample was performed according to the method proposed by the
previous work (47).
Catalyst tests. The oxidation of methane with H2 and O2 was carried out in a stainless-steel autoclave
containing a Teflon liner vessel with a total volume of 30 mL. As a typical run, the water solvent
(10 mL) and solid catalyst (27 mg) were mixed in the autoclave. Then the autoclave was heated to
the reaction temperature by an oil bath (the temperature was measured via a thermometer in the oil
bath), followed by introducing the feed gas containing 3.3% H2, 6.6% O2, 1.6% CH4, and 61.7% Ar,
and 26.8% He and maintaining the pressure at 3.0 MPa (the pressure was measured at reaction
temperature). The reaction occurred under vigorously stirring at 1200 rpm. After reaction, the
autoclave was cooled in an ice bath to <5 °C. The autoclave was directly connected into a gaseous
chromatograph (GC) containing a thermal conductivity detector (TCD) with a TDX-1 column for
analyzing the gaseous composition. The detection limit for CO2 using GC with TCD is at 2500
mv·ml/mg. After the reaction, the reactor was cooled in ice bath for 30 min, then the autoclave was
connected to the GC-TCD to analyze the gas composition. Before analysis, we used the gas in
autoclave to sweep the GC lines for 20 s. The conversion of methane, selectivity to CO2, were
calculated according to the following equations:
𝑚𝑜𝑙𝑚𝑒𝑡ℎ𝑎𝑛𝑒 =𝑚𝑜𝑙𝐴𝑟
𝐴𝑟𝑒𝑎𝑝𝑒𝑎𝑘 𝑜𝑓 𝐴𝑟 𝑖𝑛 𝑇𝐶𝐷× 𝑓(𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟) × 𝐴𝑟𝑒𝑎𝑝𝑒𝑎𝑘 𝑜𝑓 𝑚𝑒𝑡ℎ𝑎𝑛𝑒 𝑖𝑛 𝑇𝐶𝐷
4
𝐶𝑜𝑛𝑣𝑒𝑟𝑠𝑖𝑜𝑛 =𝑚𝑜𝑙𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑚𝑒𝑡ℎ𝑎𝑛𝑒 − 𝑚𝑜𝑙𝑚𝑒𝑡ℎ𝑎𝑛𝑒 𝑎𝑓𝑡𝑒𝑟 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛
𝑚𝑜𝑙𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑚𝑒𝑡ℎ𝑎𝑛𝑒× 100%
After analyzing the gaseous phase, the solid catalyst was separated from the liquor and the liquor
was analyzed by GC containing a flame ionization detector (FID) with a DV-17 column with 1-
butanol as internal standard. The methane conversion, methanol selectivity, and productivities were
calculated via the following equations:
𝑌𝑖𝑒𝑙𝑑 =𝑚𝑜𝑙𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝑚𝑒𝑡ℎ𝑎𝑛𝑜𝑙
𝑚𝑜𝑙𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑚𝑒𝑡ℎ𝑎𝑛𝑒× 100%
𝑆𝑒𝑙𝑒𝑐𝑡𝑖𝑣𝑖𝑡𝑦 =𝑌𝑖𝑒𝑙𝑑
𝐶𝑜𝑛𝑣𝑒𝑟𝑠𝑖𝑜𝑛× 100%
The productivity of methanol was calculated via the equation in the following:
𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦 [𝑚𝑚𝑜𝑙/(𝑔 × ℎ)] =𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝑚𝑒𝑡ℎ𝑎𝑛𝑜𝑙 (𝑚𝑚𝑜𝑙)
𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐴𝑢𝑃𝑑 (𝑔) × 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 (ℎ)
The concentration of methanol and other products in the liquid was also quantified by 1H NMR
(Bruker Avance-400). The measurement was calibrated by using CDCl3 as internal standard.
Typically, 0.6 mL of liquor after reaction was mixed with 0.1 mL of D2O to prepare a solution for
NMR measurement. The signal of protons from the solvent H2O is much stronger than that from the
products. Therefore, all 1H NMR spectra were recorded using a pre-saturation solvent suppression
technique to suppress the dominant H2O signal. The products of methanol, formic acid, and methyl
peroxide were quantified by comparing the peak area of product and internal standard in 1H NMR.
The oxidation of methane with H2O2 was carried out in a stainless-steel autoclave containing
a Teflon liner vessel with a total volume of 30 mL. As a typical run, the water solvent (10 mL), H2O2
(0.1 M), and solid catalyst (27 mg) were mixed in the autoclave. Then the autoclave was heated to
the reaction temperature by an oil bath (the temperature was measured via a thermometer in the oil
bath), followed by introducing the feed gas containing 10% O2, 2.5% CH4, and 47.5% Ar, and 40%
He and maintaining the pressure at 3.0 MPa (the pressure was measured at reaction temperature).
The reaction occurred under vigorously stirring at 1200 rpm. After reaction, the autoclave was
cooled in an ice bath to <5 °C. The autoclave was directed connected into a gaseous chromatograph
(GC) containing a thermal conductivity detector (TCD) with a TDX-1 column for analyzing the
gaseous composition. Then, the solid catalyst was separated from the liquor and the liquor was
analyzed by GC containing a flame ionization detector (FID) with a DV-17 column with 1-butanol
as internal standard.
The synthesis of H2O2 from H2 and O2 was carried out in a stainless-steel autoclave containing
a Teflon liner vessel with a total volume of 30 mL. As a typical run, 5.6 g of methanol, 4.4 g of H2O,
and 10 mg of solid catalyst were mixed in the autoclave. Then the autoclave was cooled to the
reaction temperature by an ice-water bath, followed by introducing the feed gas containing 5% H2,
10% O2, 45% Ar, and 40% He and maintaining the pressure at 4.0 MPa (the pressure was measured
at reaction temperature). The reaction occurred under vigorously stirring at 1200 rpm. After reaction,
5
the autoclave was directly connected into a gaseous chromatograph (GC) containing a thermal
conductivity detector (TCD) with a TDX-1 column for analyzing the gaseous composition. Then,
the solid catalyst was separated from the liquor and the liquor was analyzed by titrating aliquots of
the final solution after reaction with acidified Ce(SO4)2 (0.01 M) in the presence of Ferroin indicator.
Catalyst recycle test. In order to study the reusability of the catalyst, the solid catalyst was separated
by centrifugation after each reaction run. After drying at 80 °C for 5 h in vacuum, the catalyst was
reused in the next run.
Capacity measurement for static adsorption of water. Before the measurement, the samples were
dried at 200 °C to remove the adsorbed water. As a typical run, 0.2 g of the as-dried sample was
placed on a dish within a desiccator containing 5 g of water at the bottom. Then the desiccator was
degassed into vacuum (0.1 bar) and heated to 80 °C in an oven. After static treatment for 6 h, the
desiccator was cooled down to room temperature and the weight of the solid sample was measured.
The weight change before and after the adsorption treatment was calculated and regarded to be the
water adsorption capacity of the sample, which is calculated according the equation in the following:
𝐴𝑑𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 =𝑚𝑎𝑓𝑡𝑒𝑟 𝑎𝑑𝑠𝑜𝑝𝑟𝑡𝑖𝑜𝑛 − 𝑚𝑏𝑒𝑓𝑜𝑟𝑒 𝑎𝑑𝑠𝑜𝑝𝑟𝑡𝑖𝑜𝑛
𝑚𝑏𝑒𝑓𝑜𝑟𝑒 𝑎𝑑𝑠𝑜𝑝𝑟𝑡𝑖𝑜𝑛× 100%
Adsorption of methane in a fixed-bed tube. A quartz tube with length at 400 mm and diameter at 6
mm was employed. In the tests, 0.1 g of zeolite samples (60 mesh) and 0.2 g of quartz sand (60
mesh) were mixed and localized within the middle of the tube with catalyst feed height at ~2 cm.
More quartz sand and silica wool were employed to fix the catalyst bed and avoid its movement in
the gas flow. The methane (90 ppm in Ar) was introduced at a flow rate of 20 sccm. The
concentration of methane in the emission gas was analyzed by a GC with a TCD. To investigate the
water tolerance, the wet Ar (Ar flowing through water at 30 °C) was used as carrier gas.
Competitive adsorption of methane and methanol in a fixed-bed tube. As a typical run, 0.2 g of
zeolite samples (60 mesh) and 0.4 g of quartz sand (60 mesh) were mixed and localized within the
middle of the quartz tube (length at 400 mm and diameter at 6 mm) with feed height at ~4 cm. More
quartz sand and silica wool were employed to fix the sample bed to avoid the movement in the gas
flow. In testing the competitive adsorption, the methane and methanol (1% CH4 in He flowing
through a methanol liquor in an ice bath < 5 °C) were introduced at 1.0 sccm. The concentration of
methane and methanol in the emission gas was analyzed by a GC with FID. To investigate the
adsorption of methanol without methane, the pure He without methane was used as carrier gas
following the similar procedures in the competitive adsorption test.
6
Figure S1. Procedures for the synthesis of AuPd@zeolite-R.
R
AuPd@SiO2
Crystallization
AuPd@zeolite
AuPd@zeolite-R
R
R
R
R
R
R
zeolite
AuPd nanoparticle
7
Figure S2. SEM images of (A) ZSM-5, (B) AuPd@ZSM-5, and (C) AuPd@ZSM-5-C16. The
diameters of the zeolite crystals with 400-600 nm for these samples.
A
B
C
8
Figure S3. XRD patterns of (A) ZSM-5, (B) AuPd@ZSM-5, and (C) AuPd@ZSM-5-C16. All the
samples have typical peaks assigned to the MFI zeolite structure.
A
B
C
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
9
Figure S4. N2 sorption isotherms of (a) ZSM-5, (b) AuPd@ZSM-5, and (c) AuPd@ZSM-5-C16.
Note: The ZSM-5, AuPd@ZSM-5, and AuPd@ZSM-5-C16 samples exhibited I-type N2-sorption
curves, assigning to typical microporous structures. The ZSM-5 zeolite showed surface area at 445
m2/g. When the AuPd nanoparticles were fixed with the zeolite crystals, the resulted AuPd@ZSM-
5 had surface area at 384 m2/g. The post-silylation treatment maintained the zeolite framework and
open microporosity, as confirmed by the high surface area of AuPd@ZSM-5-C16 at 361 m2/g.
0.0 0.2 0.4 0.6 0.8 1.0
(c)
(b)
Qu
anti
ty a
bso
rbed
(cm
3/g
)
Relative pressure (P/P0)
(a)
10
Figure S5. (A) STEM image and corresponding element maps of (B) Si, (C) Au, and (D) Pd in
AuPd@ZSM-5-C16 sample. The Au and Pd element distributions are highly constant with each other,
indicating that the AuPd nanoparticle is the AuPd alloy.
A B
C D
11
Figure S6. Procedures for the section tomography TEM characterization.
AuPd@ZSM-5-C16 sample
Embedded
in resin
AuPd@ZSM-5-C16 sample
embedded in resin
Cut with
diamond knife
Sample was cut into slice with
thickness less than 100 nm
Tomogram section view of the sample
Dispersed in water
resin resin
12
Figure S7. (A) (a) 29Si NMR CP cross polarization spectrum of AuPd@ZSM-5-C16 and 29Si NMR
decoupling spectrum of (b) AuPd@ZSM-5 and (c) AuPd@ZSM-5-C16. (B) The structure of the
organosilane modified the zeolite surface. Multiple layers of organosilane must be presented on the
surface of zeolite crystals from the hydrolysis method. In the enlarged view, only one Si-C16 was
shown for clearly understanding the structure.
Note: In the 29Si NMR spectroscopy, it is observed that the Q2/Q3 signals are enhanced after
modifying the organosilanes, which might be due to the formation of new Si species, as shown in
figs. S7A-b and -c. Considering the general decoupling program of 29Si MAS NMR was difficult to
detect the Si-C signal, we showed the CP cross polarization spectrum of AuPd@ZSM-5-C16 (fig.
S7A-a), giving the T2 and T3 groups at -58 and -68 ppm, respectively. These signals are reasonably
assigned to the Si-C on the AuPd@ZSM-5-C16. By quantifying the signals of various Si species, the
molar ratio of organosilane to total amount of Si on the AuPd@ZSM-5-C16 is ~30.0%, which is
comparable to ~25.6% obtained from TG analysis (48).
-112
-106
（a）
（b）
（c）
0 -50 -100 -150 -200
ppm29Si Chemical Shift (ppm)
B
(a)
(b)
(c)Hydrophobic zone
A B
13
Figure S8. 13C NMR of (a) AuPd@ZSM-5 and (b) AuPd@ZSM-5-C16.
Note: The AuPd@ZSM-5 exhibited undetectable signals in the spectrum, suggesting the lack of
carbon species. In contrast, the AuPd@ZSM-5-C16 shows the signals at 33, 31, 24, and 14 ppm,
which are reasonably assigned to the presence of -C16 group (49).
(a)
(b)
(a)
(b)
14
Figure S9. IR spectra of AuPd@ZSM-5 and AuPd@ZSM-5-C16.
Note: Compared with AuPd@ZSM-5, the AuPd@ZSM-5-C16 gave additional peaks at 2924, 2850,
and 1460 cm-1, which are assigned to the stretching vibration of hydrocarbons species (2924 and
2850 cm-1), bending vibration of methylene (1460 cm-1) (49), confirming the successful
modification of organic groups onto the zeolite crystals by the post silylation. These data are in good
agreement with the results of solid-state NMR characterization.
3600 3000 2000 1600 1200 800 400
14602850
AuPd@ZSM-5-C16
Tra
nsm
itta
nce
Wave number (cm-1
)
AuPd@ZSM-5
2924
15
Figure S10. TG-DTA analysis of AuPd@ZSM-5-C16. The sample exhibited a significant weight
loss at 300-500 °C, due to the combustion of organic groups. The amount of organic groups was
measured at 11.5 wt% (7.0% + 4.5%) by the TG analysis, suggesting the molar ratio of organosilane
to total amount of Si at 25.6%.
0 100 200 300 400 500 600 700 80070
80
90
100
110
4.5 %
7.0 %0.5 %
464.2 C
361.8 C
247.3 C
49.6 C
4.1 %
Wei
ght
(%)
Temperature (C)
-0.4
-0.2
0.0
0.2
0.4
0.6
Tem
per
ature
dif
fere
nce
(C
/mg)
16
Figure S11. The STEM images and EDS elemental maps of the AuPd@ZSM-5-F.
Note: The NMR, IR, and TG analysis could efficiently characterize the existence of organosilanes,
but they failed to present the location/distribution of organic groups. In this case, the energy
dispersive spectrometer (EDS) seems to be powerful to observe the organic group distribution, but
it failed to characterize the carbon element because the support with carbon film was used in the
electronic microscopic characterization.
In order to overcome the aforementioned issues, we synthesized the organosilane-modified
zeolite samples using trimethoxy(3,3,3-trifluoropropyl)silane, which contains F element, benefiting
the EDS characterization to observe the distribution of organic species. This sample was denoted as
AuPd@ZSM-5-F. fig. S11 shows STEM images and the corresponding Si and F elemental maps of
the AuPd@ZSM-5-F, where the distribution of F element is in good agreement with the distribution
of Si, suggesting that the organic groups are uniformly distributed on the zeolite matrix rather than
on the individual silica species. Furthermore, we performed the tomographic section view of the
sample, which was performed by cutting the zeolite crystals into slices (fig. S6) to measure the F
element inside of zeolite crystals. In this case, we cannot observe the F signal (fig. S12), indicating
that the F element is indeed modified on the external surface of zeolite crystals.
Au Pd
Si F
17
Figure S12. The section tomography of STEM graphs and EDS elemental maps of AuPd@ZSM-5-
F slices.
Au Pd
Si F
18
Figure S13. (A) XRD pattern and (B) SEM image of Au@ZSM-5.
A
B
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
19
Figure S14. (A) XRD pattern and (B) SEM image of Pd@ZSM-5.
A
B
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
20
Figure S15. (A) XRD pattern and (B) SEM image of AuPd@ZSM-5-Me.
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
A
B
21
Figure S16. IR spectra of AuPd@ZSM-5 and AuPd@ZSM-5-Me.
Note: Compared with AuPd@ZSM-5, the AuPd@ZSM-5-Me gave additional peaks at 2938, 2861,
1394, and 955 cm-1, which are assigned to the stretching vibration of -CH3 (2938 and 2861 cm-1)
bending vibration of -CH3 (1394 cm-1) (49), confirming the successful modification of organic
groups onto the zeolite crystals by the post silylation.
4000 3600 3200 2800 2000 1600 1200 800 400
955139428612938
AuPd@ZSM-5
AuPd@ZSM-5-Me
Tra
nsm
itta
nce
Wave number (cm-1
)
22
Figure S17. (A) XRD pattern and (B) SEM image of AuPd@ZSM-5-C3.
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
A
B
23
Figure S18. IR spectra of AuPd@ZSM-5 and AuPd@ZSM-5-C3.
Note: Compared with AuPd@ZSM-5, the AuPd@ZSM-5-C3 gave additional peaks at 2933, 2851,
and 1387 cm-1, which are assigned to the stretching vibration of -CH3 (2933 cm-1) and -CH2- groups
(2851 cm-1), bending vibration of -CH3 (1387 cm-1) (49), confirming the successful modification of
organic groups onto the zeolite crystals by the post silylation.
4000 3600 3200 2800 2000 1600 1200 800 400
138728512933
AuPd@ZSM-5-C3
AuPd@ZSM-5
Tra
nsm
itta
nce
Wave number (cm-1
)
24
Figure S19. TG-DTA analysis of AuPd@ZSM-5-C3. The sample gave an obvious weight loss at
280-460 °C, due to the combustion of organic group.
0 100 200 300 400 500 600 700 80070
80
90
100
110
461.4 C
313.1 C
57.3 C
4.0 %
3.8 %
4.6 %
Wei
gh
t (%
)
Temperature (C)
-0.3
-0.2
-0.1
0.0
0.1
Tem
per
atu
re d
iffe
ren
ce (C
/mg)
25
Figure S20. Tomogram-section TEM images of AuPd@ZSM-5-C3 in randomly selected areas.
The AuPd nanoparticles appeared in the region of zeolite, confirming the successful fixation of
them within zeolite crystals.
A
B
26
Figure S21. (A) XRD pattern and (B) SEM image of AuPd@ZSM-5-C6.
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
B
A
27
Figure S22. IR spectrum of AuPd@ZSM-5-C6.
Note: Compared with AuPd@ZSM-5, the AuPd@ZSM-5-C6 gave additional peaks at 1640 and 932
cm-1, which are assigned to the framework of benzene ring (1640 and 932 cm-1) (49), confirming
the successful modification of organic groups onto the zeolite crystals by the post silylation.
3600 3000 2000 1600 1200 800 400
9321640
Tra
nsm
itta
nce
Wave number (cm-1)
28
Figure S23. TG-DTA analysis of AuPd@ZSM-5-C6. The sample gave an obvious weight loss at
280-460 °C, due to the burning of organic groups.
0 100 200 300 400 500 600 700 80070
80
90
100
110
515.4 C
358.9 C
3.5 %
6.1 %
11.0 %
Wei
gh
t (%
)
Temperature (C)
61.1 C
-0.4
-0.2
0.0
0.2
0.4
Tem
per
atu
re d
iffe
ren
ce (C
/mg)
29
Figure S24. Tomogram-section TEM image of AuPd@ZSM-5-C6. The yellow circles highlighted
the AuPd nanoparticles. This image confirms that the AuPd nanoparticles are indeed fixed within
the zeolite crystals.
30
Figure S25. (A) XRD pattern and (B) SEM image of AuPd/ZSM-5.
5 10 15 20 25 30 35 40
Inte
nsi
ty
2 Theta (degree)
A
B
31
Figure S26. N2 sorption isotherms of AuPd/ZSM-5. The N2-sorption isotherms exhibited type-I
curves, assigning to the microporous zeolite structure.
0.0 0.2 0.4 0.6 0.8 1.0
0
20
40
60
80
100
120
140
Quan
tity
abso
rbed
(cm
3/g
)
Relative pressure (P/P0)
32
Figure S27. TG-DTA curves of AuPd/ZSM-5.
0 100 200 300 400 500 600 700 80070
80
90
100
110
270.7 C
4.2 %
13.3 %
59.6 C
Wei
gh
t (%
)
Temperature (C)
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
Tem
per
atu
re d
iffe
ren
ce (C
/mg)
33
Figure S28. 1H NMR spectra of the standard methanol solutions with (A) 64, (B) 20, and (C) 10
µmol of methanol.
A
B
C
9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5
Inte
nsi
ty
12C
H3O
H
(δ=
3.2
ppm
)
13C
H3O
H
(δ=
3.1
ppm
)
13C
H3O
OH
(δ=
3.7
ppm
)
H2O
(δ=
4.7
ppm
)
CH
Cl 3
(δ=
8.1
ppm
)
HC
OO
H
(δ=
8.4
ppm
)
ppm
Inte
nsi
ty
12C
H3O
H
(δ=
3.2
ppm
)
13C
H3O
H
(δ=
3.1
ppm
)
13C
H3O
OH
(δ=
3.7
ppm
)
H2O
(δ=
4.7
ppm
)
CH
Cl 3
(δ=
8.1
ppm
)
HC
OO
H
(δ=
8.4
ppm
)
ppm9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5
ppm
Reviewer-Only Figure 5A
Inte
nsi
ty
12C
H3O
H
(δ=
3.2
ppm
)
13C
H3O
H
(δ=
3.1
ppm
)
13C
H3O
OH
(δ=
3.7
ppm
)
H2O
(δ=
4.7
ppm
)
CH
Cl 3
(δ=
8.1
ppm
)
HC
OO
H
(δ=
8.4
ppm
)
ppm9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0
ppm
34
20 30 40 50 60 70 80 900
5
10
15
20
25
Pro
d.
(mm
ol
gA
uP
d
-1h
-1)
0
20
40
60
80
100
Temperature (C)
Conv.
(%)
Figure S29. Data showing the dependences of methane conversion and methanol productivity on
reaction temperature in the methane oxidation over AuPd@ZSM-5-C16 catalyst. Reaction conditions:
10 mL of water, 30 min, 70 °C, 27 mg of catalyst, feed gas at 3.0 MPa of 3.3% H2/6.6% O2/1.6%
CH4/61.7% Ar/26.8% He, and 1200 rpm.
Note: When the reaction was performed at 90 °C, the over-oxidation occurred to form CO2 as by-
product, giving relatively low methanol productivity. Decreasing the reaction temperature to 70 °C
gives remarkably enhanced methanol productivity. In contrast, the reaction at 50 and 20 °C gives
much lower methanol productivity because of the low methane conversion. Therefore, the reactions
were performed at 70 °C for the catalytic investigations. Conv., methane conversion; Prod.,
methanol productivity.
35
Figure S30. Data characterizing the (A) hydrogen peroxide synthesis and (B) methane oxidation
using H2O2 over the AuPd@ZSM-5 and ZSM-5 samples. Reaction conditions for hydrogen peroxide
synthesis: 5.6 g of methanol, 4.4 g of water, 30 min, 0 °C, 27 mg of catalyst, 3.0 MPa of feed gas
containing 3.3% H2/6.6% O2/30% Ar/60% He, 1200 rpm. After reaction, the solid catalysts were
washed with cold methanol/tetrahydrofuran (~0 °C) for collecting all the H2O2 product. Reaction
conditions for methane oxidation: 10 mL of water, 30 min, 70 °C, 27 mg of catalyst, 0.1 M of H2O2,
3.0 MPa of feed gas containing 10% O2/2.5% CH4/47.5% Ar/40% He, 1200 rpm.
The ZSM-5 without AuPd species failed to catalyze the hydrogen peroxide synthesis from H2
and O2, and methane oxidation using H2O2, which confirms that AuPd species are necessary for the
reactions.
0
20
40
60
80
ZSM-5
AuPd@ZSM-5
HCOOH
CH3OH
0
1
2
3
4
5
CH
3O
H P
rod
. (m
mo
l g
Au
Pd
-1 h
-1)
CH
4 C
on
v.
(%)
0
30
60
90
120
ZSM-5
AuPd@ZSM-5
H2O
2 P
rod.
(mm
ol
gA
uP
d
-1 h
-1)
A B
36
Figure S31. Turnover frequencies (TOFs) and turnover numbers (TONs) of AuPd@ZSM-5-C16 and
AuPd@ZSM-5 catalysts. The values were calculated from the average methane transformation rate
in the beginning 10 min.
Note: The AuPd@ZSM-5-C16 catalyst gives the TON and TOF at 14.6 and 87.6 h-1, respectively.
These data showed clearly that this is catalytic phenomenon. Under the equivalent reaction
conditions, the AuPd@ZSM-5 catalyst gives the TON and TOF at 3.1 and 18.5 h-1, which are much
lower than those over the AuPd@ZSM-5-C16.
0
20
40
60
80
100
AuPd@ZSM-5
AuPd@ZSM-5-C 16
TO
F (
h-1
)
0
5
10
15
20
25
30
TO
N
37
Figure S32. GC curve analyzing the (A) gas and (B) liquor in the autoclave after reaction over the
AuPd@ZSM-5-C16 catalyst, and (C) gas in the autoclave after reaction over the AuPd/ZSM-5
catalyst. The reaction conditions are the same as those in Fig. 2B with reaction time at 30 min.
Butanol was added into the liquor after reaction as an internal standard.
Note: Our GC workstation (ZHIDA-2010) shows the area of two overlapped peaks that represents
the total amount of the two species. Following this principle, we divided the partially overlapped
peaks by a boundary that localized in the middle of the peaks, as presented in inset of fig. S32A.
In addition, the molar ratio of Ar and O2 in the feed gas is 9.35. After the reaction, this value
Sig
nal
Time (min)
Sig
nal
Time (min)
H2 methane
Ar
O2
methane
methanol
butanol
A
B
Sig
nal
Time (min)
C
H2
Ar
O2 methane
CO2
Ar
O2
38
could even higher because O2 was consumed in the reaction process. Therefore, the influence of O2
to the surface area of Ar (internal standard) is negligible in calculating the conversion of methane.
Following the aforementioned methods, the carbon balance values over the AuPd@ZSM-5-C16
catalyst are always over 94%.
The O2 and H2 are still remained after the reaction for 30 min (fig. S32A), giving H2, O2, and Ar
ratios at 0.046 H2/0.092 O2/0.862 Ar, as confirmed by the GC-TCD analysis. The peak of H2 is weak
because the high correction factor of H2. In addition, the over-oxidation of methanol occurred as a
dominant reaction after 30 min, which also suggests the existence of enough H2 and O2 in the reactor.
39
Figure S33. 1H NMR analysis of the products after reaction for 30 min over the AuPd@ZSM-5-C16
catalyst.
Note: The 1H NMR analysis confirms the formation of methanol and formic acid after the oxidation
of methane. Notably, the methyl peroxide appeared as a product, but it is undetectable in the GC
analysis, because methyl peroxide easily transforms into methanol in the GC at high temperature.
Therefore, the methanol productivities analyzed by GC should include the production of both
methanol and methyl peroxide.
Inte
nsi
ty
12C
H3O
H
(δ=
3.2
ppm
)
13C
H3O
H
(δ=
3.1
ppm
)
13C
H3O
OH
(δ=
3.7
ppm
)
H2O
(δ=
4.7
ppm
)
CH
Cl 3
(δ=
8.1
ppm
)
HC
OO
H
(δ=
8.4
ppm
)
ppm8.8 8.4 8.0 7.6 7.2 6.8 6.4 6.0 5.6 5.2 4.8 4.4 4.0 3.6 3.2 2.8
ppm
40
Figure S34. The detected methanol products in the water solvent and trapped in the zeolite crystals
in the AuPd@ZSM-5-C16 catalyzed methane oxidation for different time. The reaction conditions
are the same to those in Fig. 2. The methanol dissolved in the water are analyzed after separating
the solid catalysts, and the methanol tapped in the zeolite crystals was extracted via washing with
cold water/tetrahydrofuran mixture.
0
20
40
60
80
100
120
30 min15 min10 min
in zeolite
in solution
CH
3O
H P
rod
. (m
mo
l g
Au
Pd
-1h
-1)
0
20
40
60
80
100
CH
3O
H S
el. (
%)
41
Figure S35. Dependences of methane and methanol adsorption percentage on time over various
catalysts. Feed gas of methane and methanol over conventional (A) AuPd@ZSM-5 and (B)
AuPd@ZSM-5-C16 catalysts. (C) Feed gas of methanol over AuPd@ZSM-5-C16 catalyst. C0 is the
0 20 40 60 80 100 120 140
0
20
40
60
80
100
adsorption of methanol
adsorption of methane
Adsorption time (min)
c/c
0 (
%)
0 30 60 90 120 150 180
0
20
40
60
80
100
adsorption of methanol
Adsorption time (min)
c/c
0 (
%)
0 20 40 60 80 100 120 140 160 180-60
-40
-20
0
20
40
60
80
100
Adsorption time (min)
c/c
0 (
%)
adsorption of methane
adsorption of methanol
A
B
C
42
concentration of methane or methanol in the feed gas. △C = C0-Ce, where Ce is the concentration
of methane or methanol in the emission gas. The test method is shown in the experimental details.
Note: As shown in fig. S35A, the AuPd@ZSM-5 adsorbs both methane and methanol in the
beginning of the test. After 20 min, the methane adsorption was decreased with enhanced methanol
adsorption capacity. These data confirm that AuPd@ZSM-5 benefit the adsorption of methanol
because of the hydrophilic feature. Interestingly, the hydrophobic sheath efficiently changes the
adsorption behavior of AuPd@ZSM-5 in the competitive adsorption of methane and methanol. The
AuPd@ZSM-5-C16 solely adsorbs methane rather than methanol under the equivalent test
conditions, giving very slight methanol adsorption efficacy in the beginning of the test (fig. S35B,
0-30 min). Even testing for long period (>100 min), the methane adsorption efficacy still maintains
at △C/C0 at ~47%. Simultaneously, the methanol adsorption efficacy appeared at ~60% (△C/C0),
which maintains such value even for long test time. In contrast, in the methanol adsorption test over
AuPd@ZSM-5-C16 without methane, the adsorption efficacy appears to be 100% (fig. S35C). These
data confirm that AuPd@ZSM-5-C16 benefit the adsorption of methane rather than methanol in the
competitive adsorption test. Such results make us to propose that the zeolite are enriched with
methane under the reaction conditions with abundant methane, accelerating the fast desorption of
methanol to avoid over oxidation, while might explain the high selectivity of methanol in methane
oxidation.
43
Figure S36. Dependences of methanol oxidation on reaction time. Reaction conditions: 10 mL of
water, 70 °C, 27 mg of catalyst, 60 µmol of methanol, feed gas at 3.0 MPa of 3.3% H2/6.6% O2/63.3%
Ar/26.8% He, and 1200 rpm.
Note: As mentioned in the discussion of table S6, the oxidations of methane and methanol occur as
competitive reactions because of their competitive sorption behavior. The methanol with low
concentration could efficiently diffuse out of the zeolite crystals under competitive sorption with
methane, which avoids the over-oxidation of methanol on the AuPd nanoparticles. When the
methanol concentration is relatively high, it is easily over-oxidized into formic acid and CO2, which
might explain the superior selectivity of the AuPd@ZSM-5-C16 catalyst in the beginning 30 min.
In addition, we emphasized that such feature is reasonably assigned to the molecular-fence
ability of the AuPd@ZSM-5-C16 catalyst, because the AuPd/ZSM-5 catalyst appears by-product of
CO2 in the beginning of the reaction by over-oxidation of methanol product. These results also
indicate that the methanol diffusion is important for the over oxidation. We performed kinetic
investigation on the oxidation of methanol with H2 and O2 at concentrations commiserate with what
it is formed after 30 min in the general reaction over the AuPd@ZSM-5-C16 catalyst (without
methane). Because the methanol feed was added into the water solution, it is relatively difficult to
access to the AuPd nanoparticles in the beginning of the reaction, giving the reaction rate at 6.06
molMeOH molAuPd-1 h-1 (red line in fig. S36). After reaction for 30 min, the reaction rate increases to
9.84 molMeOH molAuPd-1 h-1 because more methanol is accessible to the AuPd sites within zeolite
crystals (blue line in fig. S36).
10 20 30 40 500
10
20
30
40
50
Conv
ersi
on o
f m
ethan
ol
(%)
Reaction time (min)
44
Figure S37. Dependences of the methane conversion, methanol selectivity, methanol productivity,
and H2O2 concentration on reaction time over AuPd@ZSM-5-C3. Reaction conditions: 10 mL of
water, 70 °C, 27 mg of catalyst, feed gas at 3.0 MPa of 3.3% H2/6.6 % O2/1.6 % CH4/61.7% Ar/26.8%
He, and 1200 rpm.
0
5
10
15
20
25
30
0
20
40
60
80
100
CH
3O
H S
el. (%
)
CH
4 C
onv. (%
)
0 10 20 30 40 50 60 70 800
20
40
60
80
0.0
0.5
1.0
1.5
2.0
H2O
2(m
mol
L-1)
CH
3O
H P
rod. (m
mol
gA
uP
d
-1 h
-1)
Time (min)
45
Figure S38. Data showing the dependences of (A) methane conversion and (B) methanol selectivity
on time at different reaction temperatures in the AuPd@ZSM-5-C16 catalyzed methane oxidation.
Reaction conditions: 10 mL of water, 27 mg of catalyst, 3.0 MPa of feed gas containing 3.3% H2/6.6%
O2/1.6% CH4/61.7% Ar/26.8% He, stirring rate at 1200 rpm.
Note: Higher reaction temperatures lead to faster conversion of methane. As shown in Figure S38A,
the methane conversion increased remarkably in the beginning of the reaction, reaching to 10.9%
in 40 min at 50 °C; the reaction at 70 °C was faster to give the methane conversion of 17.3% in 30
min, which further reached to 18.8% in 40 min; when the reaction temperature was 110 °C, the
methane conversion reached as high as 21.3% in 30 min.
Figure S38B shows the dependences of methanol selectivity on time in the reactions. For the
reaction temperatures at 50-90 °C, the best methanol selectivity appeared in 20-30 min, and then
decreased remarkably because the overoxidation became a dominant reaction. Notably, the reaction
at 90 °C showed higher methanol selectivity than those at 50 and 70 °C in the beginning 10 min,
which might be due to higher temperature that benefits the fast methanol formation and escape from
the zeolite crystals. After the beginning 10 min, the methanol selectivity at 90 °C increased slowly,
because the methanol over-oxidation occurred as confirmed by the significantly detectable formic
acid in the liquor. The maximized methanol selectivity appeared at 73.4% in the beginning 30 min
at 90 °C. For the reaction at 70 °C, the best methanol selectivity was 92.0%, which confirms the
optimized conditions for methane oxidation and methanol diffusion to minimize the methanol over-
oxidation in the beginning 30 min. When the reaction was at 110 °C, the methanol selectivity was
always lower than 15% during the reaction process with abundant formic acid and CO2 products
(formic acid sel. at 53% CO2 sel. at 20% at 30 min), suggesting the over oxidation as dominant
reaction at high temperature.
Prolonging the reaction time (e.g. over 140 min) caused the methanol selectivity to extremely
low value in all the reactions. For example, the reaction at 70 °C gave the methanol selectivity at
92% in 30 min, and subsequently decreased to about 20% for reaction at 170 min. For the reaction
temperature at 90 °C, similar trend was also observed, giving methanol selectivity deceased from
72% in 30 min to 5.8% in 140 min, because of the tendency for methanol over-oxidation at higher
temperatures. For these reactions at 50-90 °C, the methanol selectivity could not drop down to the
negligible values even after reaction for a long time, which might be resulted from that the hydrogen
peroxide was consumed in the long reaction period (undetectable H2O2 in the reactions at 50-90 °C
after 140 min). When the reaction was performed at higher temperature of 110 °C, the methanol
A B
0 20 40 60 80 100 120 140 160 1800
4
8
12
16
20
24
50 C
70 C
90 C
110 C
CH
4 C
on
v.
(%)
Time (min)
0 20 40 60 80 100 120 140 1600
20
40
60
80
100 50 C
70 C
90 C
110 C
CH
3O
H S
el. (%
)
Time (min)
46
selectivity was low and easily over-oxidized to the negligible value in a short time (90 min).
One would expect to see the continued conversion of methane after the methanol overoxidation
period. Actually, the methane conversions were increased very slightly in the long-period reaction
(Figure S38A), which might be due to the lack of hydrogen peroxide or H2/O2 after the methanol
over-oxidation period (70 °C, 140 min, undetectable H2O2, H2 amount is very low).
47
Figure S39. Water-droplet contact angles of various catalysts.
Note: In the investigation on zeolite wettability, the hydrophobic concept has worked on the well-
known TS-1 zeolite, but it is completely different from the hydrophobic sheath on the AuPd@ZSM-
5-R catalyst.
The hydrophobicity of TS-1 originates from the lack of Brønsted sites and the decreased defects
(silanol groups) on the zeolite framework, giving to hydrophobic zeolite framework (including both
the hydrophobic surface and hydrophobic channels within the zeolite crystal). Notably, the
hydrophobicity of TS-1, which is still weak compared with the hydrophobic materials with organic
groups (water-droplet contact angles higher than 99°), balances the diffusion of both H2O2 and
organic molecules to accelerate the organic substrate oxidation. This feature has little to do with a
fence.
In contrast, the AuPd@ZSM-5-R catalysts have hydrophilic framework but modified surface
with much stronger hydrophobicity (water-droplet contact angles at 99-115°) than the TS-1 zeolite.
Such sheath with strong hydrophobicity allows the bidirectional diffusion of methane, hydrogen,
oxygen, and methanol, but acts as a fence to hinder the escape of H2O2 when it is formed on the
AuPd nanoparticles within the zeolite crystals.
99° 112° 115°
33° 114° 33° 34°
AuPd@ZSM-5-C3 AuPd@ZSM-5-C6 AuPd@ZSM-5-C16
AuPd@ZSM-5 AuPd/ZSM-5-C16 Au@ZSM-5 Pd@ZSM-5
48
Figure S40. Data showing the (A) static water adsorption capacity measurement and (B) water
adsorption isotherms over various catalysts. The circles and squares show the adsorption and
desorption data, respectively.
Note: The hydrophobicity on AuPd@ZSM-5-C3, -C6, and -C16 catalysts might influence the
diffusion of hydrophilic molecules, such as H2O2. In order to confirm this exception, we investigated
the static adsorption tests using water to model the hydrophilic molecule (fig. S40A). As expected,
the AuPd@ZSM-5 gives water adsorption capacity at 134 mg/g, in agreement with the previous
values because of the hydrophilic zeolite micropores. However, the AuPd@ZSM-5-C3, -C6, and -
C16 exhibited poor water adsorption capacity at 10-20 mg/g under the equivalent adsorption
conditions. In addition, we also showed the water vapor adsorption isotherms of AuPd@ZSM-5 and
AuPd@ZSM-5-C16 samples. As shown in fig. S40B, the AuPd@ZSM-5 could efficiently adsorb
water, while the AuPd@ZSM-5-C16 adsorbed much less water under the equivalent P/P0. These data
indicate that the hydrophobic sheath hinders the diffusion of water molecule, which is very similar
to those reported previously (50). On the other hand, the methanol molecules could diffuse through
the hydrophobic sheath because of the amphiphilic feature of light alcohols such as methanol (50).
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
20
40
60
80
100
120
AuPd@ZSM-5-C16
AuPd@ZSM-5
Adso
rpti
on c
apac
ity
(m
g/g
)
P/P0
0
20
40
60
80
100
120
140
AuPd/ZSM-5-C 16
AuPd/ZSM-5
AuPd@ZSM-5-C 6
AuPd@ZSM-5-C 3
AuPd@ZSM-5-C 16
Adso
rpti
on c
apac
ity (
mg
/g)
AuPd@ZSM-5
A
B
49
Figure S41. Water adsorption isotherms on AuPd@zeolite samples with different Si/Al ratios. The
circles and squares show the adsorption and desorption data, respectively.
Note: Generally, when the water molecules diffuse into the zeolite micropores, they favor to be
adsorbed on the Brønsted acid sites and the silanol groups according to the results reported by
Lercher and co-workers (51). However, on the AuPd@ZSM-5-R catalysts, the water molecules are
difficult to diffuse into the internal zeolite crystals in the water adsorption tests because of the
hydrophobic organic sheath.
We normalized the concentration of Brønsted acid sites with the water adsorption capacity. In
the tests, we synthesized the zeolite catalysts with different atomic Si/Al ratios at 30, 60, 100,
and >500 [denoted as AuPd@ZSM-5 (x), where x stands for the atomic Si/Al ratio in the synthesis
gels; the siliceous sample with Si/Al ratio higher than 500 is denoted as AuPd@S-1] to adjust the
amount of Brønsted acid sites. Figure S41 shows the water sorption isotherms of these samples,
where the water adsorption capacity follows the order of AuPd@ZSM-5 (30) > AuPd@ZSM-5 (60) >
AuPd@ZSM-5 (100) > AuPd@S-1, giving the adsorbed amounts at 108, 86, 79, and 65 mg/g,
respectively. These data confirm that more Brønsted acids raised the water adsorption capacity.
Notably, the AuPd@S-1 with siliceous support (undetectable Brønsted acid sites) still exhibited
good performance for water adsorption, which should be owing to the silanol groups in the zeolite
framework (51). However, after modifying these zeolite samples with C16 organosilane, their water
adsorption capacities are all less than 14 mg/g (Figure S42). Figure S43 presented the water
adsorption capacity normalized to the concentration of Brønsted acid sites on the AuPd@ZSM-5
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
20
40
60
80
100
120
AuPd@ZSM-5 (60)
Wat
er c
apac
ity
(m
g/g
)
P/P0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
20
40
60
80
100
120
AuPd@ZSM-5 (30)
Wat
er c
apac
ity
(m
g/g
)
P/P0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
20
40
60
80
100
120
AuPd@ZSM-5 (100)
Wat
er c
apac
ity
(m
g/g
)
P/P0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
20
40
60
80
100
120
AuPd@S-1
Wat
er c
apac
ity
(m
g/g
)
P/P0
50
and AuPd@ZSM-5-C16 samples, where the modified samples always exhibited remarkably
decreased water capacities, compared to the organosilane-free samples. These results confirm the
reduced water sorption on the modified samples is mainly due to the organic sheath hindering the
water access to the internal zeolite, rather than the factor of the amount of Brønsted acid sites.
51
Figure S42. Water adsorption isotherms on the AuPd@zeolite-C16 samples with different Si/Al
ratios. The circles and squares show the adsorption and desorption data, respectively.
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
3
6
9
12
15
18
AuPd@ZSM-5-C16
(30)
Wat
er c
apac
ity
(m
g/g
)
P/P0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
3
6
9
12
15
18
AuPd@ZSM-5-C16
(60)
Wat
er c
apac
ity
(m
g/g
)
P/P0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
3
6
9
12
15
18
AuPd@ZSM-5-C16
(100)
Wat
er c
apac
ity
(m
g/g
)
P/P0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80
3
6
9
12
15
18
AuPd@S-1-C16
Wat
er c
apac
ity
(m
g/g
)
P/P0
52
Figure S43. Dependences of water adsorption capacity on the concentration of Brønsted acid sites
over AuPd@ZSM-5 and AuPd@ZSM-5-C16 samples.
0.00 0.04 0.08 0.12 0.16 0.200
20
40
60
80
100
120
Si/Al > 500
Si/Al = 100
Si/Al = 60
Si/Al = 30
Adso
rpti
on c
apac
ity (
mg/g
)
Bronsted acid sites (mmol/g)
AuPd@ZSM-5
AuPd@ZSM-5-C16
53
Samples
Amount of TMP (mg/g)
Brønsted acid Lewis acid Si-OH
AuPd@ZSM-5 12.9 0.53 7.11
AuPd@ZSM-5-C16 11.3 0.39 4.13
Figure S44. 31P MAS NMR spectra of TMP (trialkylphosphine) adsorbed on the (a) AuPd@ZSM-
5-C16 and (b) AuPd@ZSM-5 samples. The samples with atomic Si/Al ratio at 30 were used. The
table shows the amounts of adsorbed TMP on different sites of AuPd@ZSM-5-C16 and
AuPd@ZSM-5 samples.
Note: Because it is generally known that the Brønsted acid sites and the silanol groups in the zeolite
crystals are sensitive to the water adsorption capacities, we performed the 31P MAS NMR
characterization of the AuPd@ZSM-5 (30) samples before and after the organosilane modification
by using TMP as probe molecule (52). As shown in Figure S44, both samples showed the peaks at
5 and -5 ppm assigned to the TMP adsorbed on Brønsted acid sites, the peaks at -48 ppm assigned
to the Lewis acid sites, and -62 ppm assigned to the physical TMP adsorption on silanol groups.
Notably, the organosilane modification slightly influence the Brønsted acid density, as revealed by
very similar signals at 5 and -5 ppm. The adsorbed TMP on the Brønsted acid sites were calculated
to be 11.3 and 12.5 mg/g, respectively. These similar values confirm only less than 10% of the
Brønsted acid sites were eliminated by the organosilane modification. In addition, the signal of
silanol group (-62 ppm) was reduced after the medication, showing 40% of the silanol group was
eliminated.
On the basis of these data, we conclude that the modification could influence the surface
Brønsted acid sites and silanol groups, which is not enough to cause a significant drop of water
adsorption from 108.0 mg/g on the AuPd@ZSM-5 to 13.9 mg/g on the AuPd@ZSM-5-C16. We
suggest that the organic sheath acts as molecular fence to hinder the diffusion of water into the
zeolite crystals, where the water molecules are difficult to access the internal Brønsted acids and
silanol groups within zeolited crystals. As a result, they give low water adsorption capacity. These
results further confirm the molecule-fence effect to hinder the hydrophilic water molecule diffusion.
54
Figure S45. Scheme and data showing the distribution of H2O2 synthesized from H2 and O2 in the
reactor. The table represents the data in Fig. 3A in the main text. Reaction conditions in the H2O2
synthesis: 5.6 g of MeOH, 4.4 g of H2O, 30 min, ~0 °C, 10 mg of catalyst, 4.0 MPa of feed gas
with 5% H2/10% O2/45% Ar/40% He, and 1200 rpm.
Catalyst H2O2 in water
(µmol)
H2O2 in zeolite
(µmol)
H2 Conv.
(%)
Distribution feature
AuPd@ZSM-5-C16 12.8 78.3 9.2 ~86% in zeolite
AuPd@ZSM-5-C3 18.7 68.4 9.3 ~78% in zeolite
AuPd@ZSM-5 97.9 8.1 10.8 ~92% in solvent
H2O2
H2O2
H2O2
H2O2H2O2
H2O2
H2O2
H2O2H2O2
H2O2
H2O2H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2 H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2
H2O2H2O2
~92% in water~18% in zeolite
>78% in zeolite<22% in water
AuPd@ZSM-5-C3 or –C16
AuPd@ZSM-5
Water solvent
55
Figure S46. Data showing the H2O2 productivity from H2 and O2 over H- and Na-form
AuPd@ZSM-5, AuPd@ZSM-5-C16 catalysts. Reaction conditions: 5.6 g of methanol, 4.4 g of H2O,
10 mg of solid catalyst, feed gas containing 5% H2, 10% O2, 45% Ar, and 40% He, 4.0 MPa, 0 °C.
After reaction, the H2O2 product within the zeolite crystals were extracted by the cold THF at 0 °C.
0
20
40
60
80
100
120
140
160
AuPd@ZSM-5-C 16
AuPd@ZSM-5
(Na fo
rm)
AuPd@ZSM-5
(H fo
rm)
H2O
2 P
rod
. (m
mol
gA
uP
d
-1 h
-1)
56
Figure S47. Fenton reaction using the as-synthesized H2O2 from H2 and O2. (a) The rhodamine B
solution of 1mM rhodamine B in 5 mL of water, (b and c) the Fenton reaction using as-synthesized
H2O2 over (b) AuPd@ZSM-5-C16 and (c) AuPd@ZSM-5. Reaction conditions for the H2O2
synthesis: 5 g of H2O, 30 min, 0 °C, 10 mg of catalyst, 4.0 MPa of feed gas with 5% H2/10% O2/45%
Ar/40% He, and 1200 rpm. After reaction, the solid catalyst was separated. 1mM rhodamine B of
added into the aforementioned liquor. After stirring for 2 min at room temperature, 1 mmol of FeCl2
was added to start the Fenton reaction.
Note: After the Fenton reaction with H2O2 synthesized over AuPd@ZSM-5 catalyst, the rhodamine
B was totally decomposed, which means that there were abundant H2O2 in the liquor. When the
liquor over AuPd@ZSM-5-C16 was used, the color changed very slightly compared with the fresh
rhodamine B solution, demonstrating the insufficient H2O2 in the liquor.
57
Figure S48. Dependences of methane concentration in the emission gas on time in the methane
adsorption tests over various samples. The methane adsorption capacities are inserted in the figures.
Note: We measured the adsorption efficacy of the AuPd@ZSM-5 and AuPd@ZSM-5-C16 in a fixed
bed reactor with continuous flow of methane, where the methane concentration in the emission gas
was detected. The changes of methane concentration in the emission gas are very similar over the
AuPd@ZSM-5-C16 and AuPd@ZSM-5 samples. These data confirm that methane can be easily
adsorbed into both samples with adsorption capacities at 0.47 and 0.38 mmol/g, respectively. When
water was injected into the feed gas during the tests, the methane concentration in the emission gas
over the AuPd@ZSM-5 was enhanced, giving remarkably reduced methane adsorption capacity at
0.16 mmol/g. This result confirms the methane adsorption was hindered in the competitive
adsorption with water. In contrast, the AuPd@ZSM-5-C16 exhibited very similar curves and
capacities with and without water injection, supporting that the organic sheath hindered the water
adsorption in the zeolite crystals.
0 50 100 150 200 250 300
0
20
40
60
80
100
CH
4 c
on
cen
trat
ion
(p
pm
)
Adsorption time (min)
AuPd@ZSM-5-C16
A
0 50 100 150 200 250 300
0
20
40
60
80
100
Water
AuPd@ZSM-5-C16
CH
4 c
once
ntr
atio
n (
ppm
)
Time (min)
0 50 100 150 200 250 300
0
20
40
60
80
100
AuPd@ZSM-5
CH
4 c
on
cen
trat
ion
(p
pm
)
Time (min)
B
0 50 100 150 200
0
20
40
60
80
100
AuPd@ZSM-5
CH
4 c
once
ntr
atio
n (
ppm
)
Time (min)
Water
C D
0.47 mmol/g 0.45 mmol/g
0.38 mmol/g 0.16 mmol/g
58
Figure S49. Scheme showing the molecular diffusions in the methane oxidation process. The
thickness of the arrows represents the diffusion amount.
Note: The reaction proceeds multiple reaction and diffusion steps: (I) the H2 and O2 diffuse through
the hydrophobic sheath and react on the AuPd nanoparticles to form H2O2 (or peroxide species),
which is trapped within the zeolite crystals because of the hydrophobic sheath hinders its escape;
(II) the methane molecules diffuse through the hydrophobic sheath and access to the AuPd
nanoparticle surface; (III) the methane was oxidized by the H2O2 (or peroxide species) to form
methanol. In the beginning of the reaction, the slight amount of methanol was formed and most
methanol was trapped within the zeolite crystals, giving to a low methanol amount in the water
solution; (IV) more methane molecules diffuse into the zeolite crystals to occupy the micropores,
and the methanol product rapidly diffuses through the hydrophobic fence into the water solution
because of the methane-methanol competitive adsorption.
H2 + O2
H2O2H2O2
CH4
H2O2
CH4
H2O2
CH4
H2O2
H2O2
H2O2
CH3OH
H2O2
H2O2
CH4
H2O2
CH4
CH4
CH3OH
H2O2
H2O2
H2O2
H2O2
H2O2
CH4
H2O2
CH4
H2O2
CH4
CH4
CH4
CH3OH
H2O2
CH4
CH4
CH4
CH3OH
Hydrophobic sheath
Zeolite containing AuPd nanoparticles
（I） （II）
（IV） （III）CH3OH
CH3OH
CH3OH
CH3OH
CH4
CH4
CH4
59
0
20
40
60
80
Blank
AuPd/ZSM-5-C 16
AuPd@ZSM-5
AuPd@ZSM-5-C 16
AuPd@ZSM-5-C 6
AuPd@ZSM-5-C 3
CH3OH
HCOOH
Pro
d.
(mm
ol
gA
uP
d
-1 h
-1)
0
1
2
3
4
5
CH
4 C
on
v.
(%)
Figure S50. Data characterizing the methane oxidation with H2O2 over various catalysts. Reaction
conditions: 10 mL of water, 30 min, 70 °C, 0.1 M of H2O2, 27 mg of catalyst, 3.0 MPa of 10%
O2/2.5% CH4/47.5% Ar/40% He, and 1200 rpm.
60
Figure S51. Recycle tests of the AuPd@ZSM-5-C16 for CH4 selective oxidation. After each reaction
run, the catalyst was dried at 100 ºC for 4 h. Conv., methane conversion; pink column, methanol
productivity; blue column, formic acid productivity.
0 1 2 3 4 5 6 7 8 9 10 110
20
40
60
80
100
120
140
160
Runs
0
2
4
6
8
10
12
14
16
18
Co
nv
. (%
)
Pro
d.
(mm
ol
gA
uP
d
-1h
-1)
61
Table S1. NMR analysis of the standard methanol solutions.
Entry Methanol in the feed
(µmol)
Methanol analyzed by NMR
(µmol)
The NMR spectra in
fig. S28
1 10 9.1 C
2 20 18.7 B
3 64 59.2 A
Table S2. GC-FID analysis of the standard methanol solutions.
Entry Methanol in the feed
(µmol)
Methanol analyzed by GC-
FID (µmol)
1 10 11.0
2 30 30.5
3 40 39.3
4 64 61.1
Note: We systemically compared the data analyzed by GC and NMR by using a series of standard
methanol solutions. For the methanol amount of 10, 20, and 64 µmol in the standard methanol
solutions, it is obtained the methanol amount at 9.1, 18.7, and 59.2 µmol by NMR analysis (fig. S28
and table S1). By analyzing the standard methanol solutions containing 10, 30, 40, and 64 µmol
with GC-FID technique, the obtained results are 11.0, 30.5, 39.3, and 61.1 µmol (table S2). These
data support that both GC-FID and 1H NMR could effectively analyze the reaction products.
62
Table S3. Methanol productivity over the AuPd@ZSM-5-C16, AuPd@ZSM-5, and AuPd/ZSM-5
catalysts.
Catalyst Conditions Dispersion
(%)*
Methanol
productivity
(mmol gAuPd-1 h-1)†
AuPd@ZSM-5-C16 0.03 H2/ 0.06 O2/ 0.016
CH4/0.62 Ar/0.28 He,
70 °C, 30 min
14.2 645.1
AuPd@ZSM-5 15.6 210.9
AuPd/ZSM-5 27.3 17.7
* (molar ratio of accessible metal sites to the total amount of metal, measured by H2 pulsed sorption
tests.
† calculated on the basis of accessible AuPd sites.
Note: If there is no special note in this manuscript, the methanol productivities were calculated on
the basis of total amount of AuPd in the reaction system.
In order to provide more information about the reaction, table S3 presents the dispersion degrees
of various catalysts and the corresponding methanol productivities on the basis of accessible metal
sites. Lower AuPd dispersion values over the AuPd@ZSM-5-C16 and AuPd@ZSM-5 than that over
the AuPd/ZSM-5 is due to the zeolite fixed structure, where the zeolite framework partially blocked
the surface of metal sites. However, the AuPd@ZSM-5-C16 still exhibited higher methanol yield
than the AuPd/ZSM-5 catalyst although the later one is more accessible, confirming the important
role of zeolite fixed structure.
63
Table S4. Catalytic data of different catalysts.
Entry Catalyst Conditions CH3OH
amount
(µmol)
Prod.
(mmol gAuPd-1 h-1)
Ref.
1 AuPd@ZSM-5 0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
23.0 32.9 This work
2 AuPd/ZSM-5 0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
7.1 10.1 This work
3 AuPd@ZSM-5-
C3
0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
59.2 84.6 This work
4 AuPd@ZSM-5-
C6
0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
60.8 86.9 This work
5 AuPd@ZSM-5-
C16
0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
64.1 91.6 This work
6 AuPd/TiO2 0.009 H2/ 0.002
O2/ 0.76
CH4/0.22 N2
1.3 10.5 3
7 AuPd/TiO2 0.009NADH/
0.002 O2/ 0.76
CH4/0.22 N2
4.5 35.9 3
8 AuPd colloid 30 bar CH4
50 µmolH2O2
5 bar O2
7.6 11.8 2
9 AuPd@SiO2 0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
trace trace This work
10 AuPd@SiO2-
C16
0.03 H2/ 0.06
O2/ 0.016
CH4/0.62
Ar/0.28 He
trace trace This work
64
Note: In entry 7, the NADH is reduced nicotinamide adenine dinucleotide (NAD). The AuPd
nanoparticles fixed within amorphous silica (AuPd@SiO2) and further functionalized with
hydrophobic organosilane (AuPd@SiO2-C16) exhibited trace amount of methanol product (entry 10),
confirming the importance of zeolite crystals for the efficient oxidation of methane.
65
Table S5. Data showing the carbon balances before and after the reaction in the AuPd@ZSM-5-C16
catalyzed methane oxidation.
Reaction conditions: 10 mL of water, 70 °C, 27 mg of catalyst, feed gas at 3.0 MPa containing 3.3%
H2/6.6% O2/1.6% CH4/61.7% Ar/26.8% He, 1200 rpm.
* [(the total amount of carbon after reaction)/(amount of methane before reaction)]*100%
† After each reaction, the catalyst was washed with THF to collect all the methanol and formic acid
within the zeolite crystals.
Note: Table S5 shows the product distributions and carbon balance values in the methane oxidation
on the AuPd@ZSM-5-C16 catalyst. In the beginning of the reaction, the carbon balance value was
lower than 96% because partial methanol product was trapped within the zeolite crystals. If the
tapped methanol was extracted by tetrahydrofuran, the carbon balance value reached to 98.5%. After
reaction for 30 min, the methanol, formic acid, and methyl peroxide species were detected in the
products, giving the carbon balance value at >99%. When the reaction was performed for longer
reaction time, the methanol was overoxidized to formic acid and carbon dioxide, which are
detectable in the liquid and gaseous phase, respectively. Even in the deep oxidation run (reaction
for 140 min to minimize the methanol selectivity with CO2 as dominant product), the carbon balance
value was at 94%. These carbon balances were lower than 100% because a slight amount of products
trapped within the zeolite crystals and/or formation of some other undetectable products.
Entry Before
reaction
Reaction
time
(min)
After reaction Carbon
balance
(%)* CH4
(µmol)
CH4
(µmol)
CH3OH
(µmol)
HCOOH
(µmol)
CO2
(µmol)
CH3OOH
(µmol)
1 400 0 400.0 trace trace trace trace >99
2 400 15 364.4 19.6 <1.0 trace trace 96.0
3† 400 15 364.4 27.8 2.0 trace trace 98.5
4 400 30 330.8 63.7 3.6 trace trace >99
5 400 70 322.8 47.6 8.9 6.1 3.1 97.1
6 400 140 322.0 20.4 13.3 14.7 5.4 94.0
66
Table S6. The catalytic results in the feed gas of H2, O2, and methane with different methanol
concentration over the AuPd@ZSM-5-C16 catalyst.
Entry Methanol in the feed
(µmol)
Methane conv. (%) Methanol after reaction (µmol)
1 0 17.3 64
2 5 16.8 67
3 15 15.4 69
4 60 10.1 73
Reaction conditions: 10 mL of water, 30 min, 70 °C, 27 mg of AuPd@ZSM-5-C16, feed gas at 3.0
MPa of 3.3% H2/6.6% O2/1.6% CH4/61.7% Ar/26.8% He, and 1200 rpm.
Note:
It is well known that methanol is more active than methane in the oxidation. In the beginning of
the reaction within 30 min, the methane-methanol competitive sorption benefits the methanol
desorption to avoid the methanol over-oxidation. When the methanol concentration in the reaction
system was high enough (e.g. after reaction for 30 min), the peroxide species favors to react with
methanol rather than methane.
In order to confirm this viewpoint, we performed the reaction with both methane and methanol
at concentrations commiserate with what they are formed after 30 min in the reaction of this
manuscript. After reaction for 30 min, the conversion of methane was at 10.1%, which is much
lower than that in the general run (17.3%) without methanol in the feed (entries 1 and 4 in table S6).
In this case, the methanol amount in the reactor after the reaction is 73 µmol, increasing by 13 µmol
compared with 60 µmol in the feed. However, such value (13 µmol) is much less than the amount
of converted methane, demonstrating the over-oxidation indeed occurred in the mixture of methane
and methanol.
In addition, we also performed similar reactions with different methanol concentration in the
feeds containing H2, O2, and methane. Table S6 presents the change in methane and methanol
amount in the reactor before and after the reaction at 70 °C for 30 min. With low concentration of
methanol in the feed, it is observed that the oxidation of methane into methanol is a dominant
reaction. In contrast, when relatively high concentration of methanol exists in the feeds, the over-
oxidation of methanol is a major reaction with detectable CO2 in the gaseous products.
In sum, all these data confirm that the methanol amount in the reaction system remarkably
influence the reaction pathways. After 30 min, the methanol concentration is high enough to start
the over-oxidation, which strongly hindered the methane oxidation in some extent.
67
Table S7. Data showing the distribution of H2O2 in methane oxidation process.
Reaction conditions: 10 mL of water, 30 min, 70 °C, catalyst 27 mg, feed gas at 3.0 MPa of 3.3%
H2/6.6% O2 /1.6% CH4/61.7% Ar/26.8% He, and 1200 rpm.
Note: On the basis of the zeolite pore volume and enriched amount of H2O2, the H2O2 concentration
in the zeolite crystal is calculated to be 0.46 mol/L (occupying about 41% of the nanoporous
volume), which is ~15,000 fold of the H2O2 concentration (29.3 μmol/L) in the water solvent,
confirming the superior effect of molecular fence in H2O2 enrichment.
Catalyst H2O2 in water
(µmol)
H2O2 in zeolite
(µmol)
H2 Conv.
(%)
Distribution feature
AuPd@ZSM-5-C16 7.7 36.1 13.7 ~82% in zeolite
AuPd@ZSM-5-C3 9.0 32.0 13.3 ~76% in zeolite
AuPd@ZSM-5 58.3 9.8 14.8 ~86% in solvent
References and Notes
1. R. A. Periana, D. J. Taube, S. Gamble, H. Taube, T. Satoh, H. Fujii, Platinum catalysts for
the high-yield oxidation of methane to a methanol derivative. Science 280, 560–564
(1998). doi:10.1126/science.280.5363.560 Medline
2. N. Agarwal, S. J. Freakley, R. U. McVicker, S. M. Althahban, N. Dimitratos, Q. He, D. J.
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