Environmentally Benign Bioderived Carbon Microspheres-Supported

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Environmentally Benign Bio-derived Carbon Microspheres-supported Molybdena Nanoparticles as Catalyst for the Epoxidation Reaction Dhananjay S. Doke, Shubhangi Bhalchandra Umbarkar, Manoj B. Gawande, Radek Zboril, and Ankush V. Biradar ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b02229 • Publication Date (Web): 18 Nov 2016 Downloaded from http://pubs.acs.org on November 20, 2016

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ACS Sustainable Chemistry & Engineering

Environmentally Benign Bio-derived Carbon Microspheressupported Molybdena Nanoparticles as Catalyst for the Epoxidation Reaction Dhananjay S. Doke,# Shubhangi B. Umbarkar,#‡ Manoj B. Gawande,§ Radek Zboril,§ Ankush V. Biradar$ # ‡* $

Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemical Research Institute, Bhavnagar-364002, Gujarat, India. # Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, Maharashtra, India. ‡ Academy of Scientific and Innovative Research, ACSIR, Anusandhan Bhawan, New Delhi-110 001, India. § Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic. Corresponding author’s E-mail: [email protected]

ABSTRACT: A one-pot synthesis of molybdenum oxide nanoparticles (NPs) supported on bio-derived carbon microspheres

is reported. The catalyst was synthesized by the low temperature hydrothermal (LTH) method using D-glucose and bagasse as the carbon source. The carbonization of bagasse resulted in the formation of non-uniform carbon microspheres while glucose resulted in uniform carbon spheres. SEM and STEM elemental mapping show the uniform distribution of molybdenum oxide NPs over the carbon microspheres. XPS spectroscopy confirmed that molybdenum was in Mo6+ oxidation state. The 1% MoO3 supported on carbon microspheres derived from D-glucose showed excellent catalytic activity up to 100% olefin conversion with 100% epoxide selectivity using organic tert-Butyl hydroperoxide as an oxidant. The catalyst was successfully used up to five cycles without losing substantial activity and selectivity. KEYWORDS: Carbon microspheres• Hydrothermal synthesis• Epoxidation• TBHP• Heterogeneous catalysis

Introduction Carbon-based materials have long been known for their versatile applications such as adsorbent, rubber enrichment, fuel-blending, or pigments.1 Recently, carbonaceous materials have attracted more attention in various types of applications such as adsorbents, gas storage, electrode, carbon fuel cells, and catalyst supports.2–3 The aforementioned carbon was synthesized by carbonization method using petroleum coke and wood under controlled air.4 Lately, different morphologies of carbon have been reported using different methods including, for instance, laser ablation,5 hydrothermal carbonization,6 or high-voltage arc.7 Amongst the various synthetic methodologies employed, hydrothermal synthesis merits the one-pot synthesis of metal oxides/carbon having distinctive nano/micro assembly. Several reports appear in the literature concerning the synthesis of different structures or morphologies of carbon such as carbon sphere,8 and hollow carbon sphere,9–10 by low temperature hydrothermal (LTH) synthesis using readily available sugars (glucose). Furthermore, there are reports on utilization of biomass (e.g., nut shells, wood and peat) for the synthesis of different types of carbons. This biomass consists of high amount of cellulose and hemicellulose. Therefore, they can be used as a raw material for carbon synthesis. Bagasse (BA) from sugarcane can be another very useful bio-derived carbon source, which is produced annually in large quantities as a waste material by sugar mills. Generally, this bagasse is burned for the generation of steam for electricity production. However, during this

process, a large amount of carbon is released into the atmosphere, which adds to the increase in atmospheric carbon dioxide. Hence, possible use of this cellulosic material for carbon synthesis could be an interesting value addition. To this end, some efforts have been made to utilize BA as a raw material for the synthesis of carbon by physical activation and carbonization.11 Various carbon-supported metal oxides were used as catalysts for different organic transformations.12 Among these, carbon-supported molybdena catalysts represent a special class owing to their catalytic applications in Fischer-Tropsch synthesis,13 alkane isomerisation,14 hydrodesulfurization,15 higher alcohol synthesis,16 Fridel-Crafts alkylation,17 etc. For instance, Radovic et al.13 have used carbon-supported molybdena catalysts for hydrodesulfurization and Fischer-Tropsch synthesis. Del Gallo et al.14 have used MoO3-carbon for selective isomerization of nbutane. Zdražil and co-workers15 have synthesized MoO3 supported on carbon and used it for hydrodesulfurization activity. Shoja and co-workers16 synthesized alkalized MoO3 nano catalyst supported on carbon nanotubes (CNTs) for higher alcohol synthesis in a fixed bed micro-reactor. Also, carbon microspheres supported molybdena was used for Friedel-Crafts alkylation reaction.17 Hong et al.18 have reported hydrodeoxygenation of maize oil by using molybdenum supported on reduced graphene oxide, activated charcoal, graphite and fullerenes. Very few reports are available dealing with the utilization of molybdena supported on carbon catalysts for the epoxidation of

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olefins. Goto et al.19 have reported epoxidation of olefin using molybdena supported on activated carbon and tert-Butyl hydroperoxide (TBHP) as an oxidant with 95% conversion and epoxide as the sole product. However, the recyclability of the catalyst was not studied. Chen and co-workers20 have reported the epoxidation of olefin using magnetic γ-Fe2O3@C@MoO3 core-shell catalyst. Despite an excellent catalytic activity as well as recyclability (97.3% conv. and 99.9% sel.), they have used complicated synthesis procedures, high MoO3 loading (37.8%) and hazardous chemicals like HNO3. In another report, Hyeon et al.21 carried out olefin epoxidation by employing magnetically separable mesoporous molybdena silica microspheres. They obtained a 99% cyclooctene-oxide yield in 5 h. Recently, we utilized molybdena supported on oxide supports synthesized by the “resin burn method” for olefin epoxidation.22 The MoO3/SiO2 catalyst showed high activity in terms of >90% conversion, 96% selectivity and recyclability. A large amount of research is being carried for the synthesis of high yield of epoxides which are used as synthons for the synthesis of a wide variety of chemicals such as drugs, agrochemicals and food additives.23–24 Herein, we report synthesis and catalytic activity of molybdenum oxide NPs supported on bioderived carbon microspheres. The carbon microspheres (CMs) were synthesized using different precursors in one-step hydrothermal synthesis and used olefin epoxidation reactions.

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product tries to minimize the pressure by forming a spherical shape.26 The other possibility for the formation of CM is direct self-condensation and decarboxylation of cellulose and hemicellulose under the reaction conditions. The phase purity and crystallinity of synthesized catalysts were analyzed by powder X-ray diffraction. The Bragg’s diffraction patterns of the CMs and the MoO3/CMs catalyst showed sharp diffraction peak at 25° which corresponds to the (002) plane of the graphitic carbon framework (Figure 1A-a-c).27 Whereas, a broad peak observed in the case of MoO3 NP supported on Dglucose derived carbon clearly indicates that the CMs are amorphous in nature (Figure 1A-d-e). The 10A-MoO3/BCMs (10 wt%, MoO3/CMs prepared from bagasse and ammonium heptamolybdate) (ESI S1†) showed sharp Bragg reflections at 2θ = 23.4 (110), 26.2 (040) and 36.2° (060), which are characteristic peaks of the α-MoO3 orthorhombic phase having crystalline nature (Figure 1A-f, JCPDS No. 05-0508).28 Other samples containing 1% MoO3 NPs supported on CMs did not show any diffraction peaks of molybdena due to its lower percentage (Figure 1A-b-e).

Results and Discussion A series of molybdenum oxide supported carbon microspheres (MoO3/CMs) were synthesized by one-pot hydrothermal carbonization using different carbon sources and molybdena precursors (Scheme 1). Figure 1. A) p-XRD patterns of the (a) BCM; (b) 1AMoO3/BCMs; (c) 1S-MoO3/BCMs; (d) 1S-MoO3/GCMs; (e) 1AMoO3/GCMs; (f) 10A-MoO3/BCMs and B) FT-IR spectra of (a) 1A-MoO3/BCMs; (b) 1A-MoO3/GCMs; (c) 10A-MoO3/BCMs; (d) 1S-MoO3/GCMs and (e) 1S-MoO3/BCMs. Scheme 1. Schematic for synthesis of MoO3/CMs from bioderived carbon precursors. Different carbon sources such as bagasse (BA) or D-glucose (DG), oxalic acid (OA) and molybdena precursor’s, i.e., NH4Mo7O26·4H2O (AHM) or Na2MoO4·2H2O (SM) were dissolved in distilled water, and packed in an autoclave. The carbonization was carried out for 12 h by keeping the autoclave in the furnace at 180 °C under static conditions. The reaction occurred between the finely powdered BA, DG and OA at the reaction temperature. For convenience purpose the respective catalysts were named as BCM-carbon spheres synthesized from bagasse, GCMS-carbon spheres synthesized from glucose, 1AMoO3/BCMs- used 1% NH4Mo7O26·4H2O supported on BCMs, 1S-MoO3/BCMs- used 1% Na2MoO4·2H2O supported on BCMs, 1S-MoO3/GCMs- used 1% Na2MoO4·2H2O supported on GCMs, 1A-MoO3/GCMs- used 1% NH4Mo7O26·4H2O supported on GCMs and 10A-MoO3/BCMs used 10% NH4Mo7O26·4H2O supported on BCMs. The hydrothermal treatment of finely milled fibers of BA/DG led to the formation of CMs. The CMs were formed through two possible pathways. First, the hemicellulose in BA undergoes hydrolysis, which is catalyzed by a strong dicarboxylic acid, i.e., oxalic acid (OA)25 to yield glucose before further dehydration yielding 5-(hydroxymethyl)furfural (5-HMF). 5-HMF is further condensed and polymerized to form solid carbon with -OH, -C=O and -COOH groups on the carbon surface. Also, owing to the auto-generated high pressure, the polymerized

The FTIR analysis (Figure 1B and for full range spectra see S2†) of all the samples showed distinct vibrational bands of C=C, C=O, C-H stretching. The bands at 1702 and 1613 cm−1 can be attributed to C=O and C=C, respectively.29-31 The bands at approximately 2900 and 3300–3700 cm-1 corresponded to stretching vibrations of aliphatic C-H and O-H, respectively (see ESI S2†).32-33 The intensities of the hydroxyl or carboxyl groups are weaker in DG carbon as compared to BA carbon, thereby disclosing dehydration reaction which was more prominent in DG carbon as compared to bagasse carbon. The new band appearance at 1613 and 1510 cm−1 conforms the increased aromatization of carbon. After completion of glucose carbonization reaction, the band intensity at 1702 cm−1 (C=O) and the wide band at approximately 3000–3700 cm−1 (O–H) (Figure 1B-b and d) disappeared because of oxygen removal from parent carbon. The band intensity increased at 1613 cm−1 due to the more aromatic carbon (C=C) in the carbon framework. These data reveal an increase in the aromatization as the reaction temperature rises, which is typical for a carbonization process.33 Due to low concentration of molybdenum on the catalyst surface, its FT-IR adsorption peaks appeared in very low intensity (Figure S2). The characteristic absorption band at 970 cm−1 for the terminal Mo=O bond and the peaks at 902 and 801 cm−1 are attributed to the Mo–O–Mo vibrations of Mo6+, which indicates the presence of MoO3 nanoparticles on the carbon support. Other stretching bands not appeared prominently due to most of molybdenum might be buried in the carbon framework.34


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The surface area and pore diameter of the synthesized carbon microspheres was determined by Brunauer–Emmett–Teller (BET) using N2 adsorption (ESI Fig. S3†). The surface area of 1A-MoO3/GCMs was found to be 46.3 m2/g with average pore diameter 16.4 nm, whereas 10A-MoO3/GCMs sample showed 5 m2/g with pore diameter 30.91 nm. The porous material formed due to the evolution of ammonia from the AHM. TEM image of 1S-MoO3/BCMs (prepared from sodium molybdate precursor) disclosed that carbonization of bagasse results into non-uniform size CMs having MoO3 nanoparticles of size 5-10 nm uniformly distributed over CMs (Figure 2A, and B). The reason for appearance of separate molybdena nanoparticles was due to the weak interactions among sodium molybdate and BCMs matrix. SEM elemental mapping of the same sample shows uniform distribution of all the metals over the carbon microspheres (Figure S4(b)†).

MoO3/GCMs. Elemental analysis results were found to be in agreement with EDAX analysis (Figure 3 E).

Figure 3. STEM image of 1A-MoO3/GCMs showing (A) Mo atoms; (B) oxygen atom; (C) overall dispersion of Mo, oxygen and carbon of 1A-MoO3/GCMs; (D) HAADF image of 1AMoO3/GCMs and (E) STEM-EDS of 1A-MoO3/GCMs.

Figure 2. (A-B) HRTEM micrographs of 1S-MoO3/BCMs; (C) SEM elemental mapping of 1S-MoO3/BCMs; (D-E) HRTEM micrographs of 1A-MoO3/GCMs; (F) SEM elemental mapping of 1AMoO3/GCMs. The yellow colour represents molybdenum, the green colour oxygen and the red colour carbon. Furthermore, ICP-OES analysis showed 9.79 × 10-2 mmoles/g molybdenum content. This result also corresponds with SEM (including elemental mapping) and EDAX analysis of other BA carbon based materials is shown in Figure. S4 to S6†. MoO3/BCMs showed a non-uniform structure, as it is in the case of 1A-MoO3/BCMs and 10A-MoO3/BCMs (prepared from ammonium heptamolybdate (AHM) precursor). The reason for the formation of non-uniformly sized particles in the case of BA carbon is that BA being composed of large polymeric units of monosaccharides and the presence of ammonia which is released from AHM that inhibits the growth of uniform carbon microspheres. The CMs synthesized from the DG are monodispersed and spherical in shape. The average particle size of the MoO3 nanoparticle was 4.2 nm for the 1A-MoO3/GCMs and 4.16 nm for 1SMoO3/GCMs catalysts (see TEM and SEM including elemental analysis and average particle size of MoO3/GCMs; ESI, Figure S4, S7, 8-10†). No separate MoO3 NPs were observed for AHM supported on GCMs due to being embedded in the carbon matrix. Elemental mapping of various components is displayed in Figure 2 (C-F). STEM analysis of 1A-MoO3/GCMs is shown in Figure 3 and the results confirm the presence of Mo atoms (red color) on the surface of carbon spheres (green color). Oxygen atoms (blue color) are homogeneously present on bagasse carbon sample. The STEM result further corroborates the distribution of molybdena NPs within the material (Figure 3 C). Figure 3 D shows the high angle annular dark field (HAADF) STEM image of 1A-

XPS analysis was carried out to obtain the chemical and electronic state of molybdena on CMs. XPS spectra of 1AMoO3/GCMs are shown in Figure 4. XPS spectra of all other samples are given in S10-13†. XPS analysis of molybdena supported on CMs showed peaks at 232.6 eV and 235.6 eV due to Mo3d5/2 and Mo3d3/2, respectively (Figure 4B). Peak fitting of C1s shows multiple signals between 284.6 and 288.1 eV, which arises from C=C, CHx, C-C, -C-OR, -C=O, and -COOH groups, (ESI S16 C †).35-36 Also, the association of oxygen to carbon was validated by the O1s spectrum, in which multiple signals appeared at 531.7 and 533.0 eV.36 These results correspond with those obtained from the FTIR revealing the presence of both aromatic and aliphatic carbon functional groups.

Figure 4. XPS spectra of (A) 1A-MOO3/GCMs, (B) Mo present in 1-MoO3/GCMs; (C) carbon present 1A-MoO3/GCMs, (D) oxygen present in 1A-MoO3/GCMs. Catalyst activity The catalytic activity of the synthesized catalyst was evaluated for olefin epoxidation (Scheme 2). The model reaction was carried out with cyclooctene using different catalysts with TBHP as an oxidant at 80 °C.



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Scheme 2. Cyclooctene epoxidation reaction. Initially, the reaction was carried out without catalyst or active metal-loaded catalyst to test the catalytic properties of the only CMs. It gave only 12% conversion, which could be attributed to the auto catalysis by the oxidant.37 When 10A-MoO3/BCMs was used as the catalyst, 90% of the substrate was converted with 100% selectivity for the corresponding epoxide within 3 h (Table 1, entry 3). 1A-MoO3/BCMs gave only 22% conversion with 69% selectivity for the epoxide, because of the non-uniform size and shape of the former (Figure S4-A†). 1S-MoO3/BMCs were more catalytically active despite of the non-uniform size and shape of the support. This may be attributed to the uniform distribution of molybdenum nanoparticles of 0.5-10 nm size over the carbon surface (Figure S7†). Table 1. Results of cyclooctene epoxidation using different MoO3 wt% supported on different carbon spheres.a Entry

Catalysts

% Conv.

1.

Without catalyst

12

% epoxide Sel. 100

Rate Constant, k (mol-1s-1) 0.0076

2.

CMs

12

100

0.0076

3.

10A-MoO3/BCMs

90

100

0.5000

4.

1A-MoO3/BCMs

22

69

0.0157

5.

1S-MoO3/BCMs

72

100

0.1429

6.

1S-MoO3/GCMs

60

100

0.0833

7.

1A-MoO3/GCMs

80 100 0.2222 100* 100 a Reaction conditions: Cyclooctene: 2.5 mmol; oxidant: 5.5 M TBHP in decane (2.5 mmol); catalyst: 10 wt% of substrate (0.019 mM of MoO3); solvent: 1,2-dichloroethane: 6 g; chlorobenzene (internal standard): 15 mmol; time: 2 h; *3 h, temperature: 80 °C. A cyclooctene conversion of 72% was obtained with 100% selectivity for the epoxide. 1S-MoO3/GCMs catalyst showed 60% cyclooctene conversion and 100% epoxide selectivity. Among other catalysts, 1A-MoO3/GCMs showed a maximum catalytic activity of 100% cyclooctene conversion and 100% epoxide selectivity. The turnover frequency (TOF) was found to be as high as 515 h-1. 1A-MoO3/GCMs had a uniform size and shape; therefore molybdena was more available for olefin epoxidation. The catalytic activity of molybdena supported on GCMs was superior to that of BA-derived catalysts. This may be due to the greater amorphous nature of the GCMs and the well-dispersed molybdena embedded in the GCM matrix compared to BCM. Also, the molybdena precursor AHM interacts more favourably with D-glucose or BA compared to SMA during the hydrothermal treatment. Thus, catalytic materials using AHM as the molybdena precursor gave better catalytic results. The progress of the reaction was monitored by periodically withdrawing the samples and injecting them into a gas chromatograph. The time versus conversion and selectivity curve for the aforementioned reaction showed linear increase in conversion with constant epoxide selectivity (Figure S14†).

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Then, the best catalyst (1A-MoO3/GCMs) was chosen to study the wider applicability for different substrates. The epoxidation of substrate like cyclohexene having more ring strain was also successfully converted into an epoxide (~100%) product (Table 2, entry 1) with a little longer reaction time (0.0185 mol-1s1 ). Both cyclooctene and two double bond containing alkenes converted efficiently. Alkenes with two double bond took a longer reaction time along with less selectivity towards the second bond epoxidation, i.e., 58% and 48% selectivity for the 1,2-epoxide and 5,6-diepoxide, respectively (Table 2, entry 3). On the contrary, styrene, did not show promising results under identical reaction conditions (Table 2, entry 4), as it gave 48% styrene conversion with only 44% epoxide selectivity which may be attributed to extra stability of styrene which may further cleave the double bond to yield benzaldehyde and miscibility of styrene in give reaction condition was very less. Also, less reactive molecules like n-hexene, 3-butene-2-ol and 3-butene-1-ol were also converted to epoxide in high reaction rate (0.2222 mol-1s-1) to selectively epoxide as product. An industrially important fragrance molecule, limonene also gave high epoxide selectivity. Table 2. Oxidation of various olefins catalyzed by 1AMoO3/GCMs using organic TBHP as an oxidant.a Entry Substrate Time % % Epox- Rate Constant, (h) Conv. ide Sel. k (mol-1s-1) 2

25

100

13

100

100

2

80

100

3

100

100

2

27

100

13

98

58*

2

13

43

13

48

44

2 12 2 12

45 90 47 86

85 87 100 100

2

48

100

12

78

100

2

53

85

12

96

86#

1.

0.0185

0.2222

2. 0.0205

3. 0.0083

4.

5. 6.

0.0455 0.0493 0.0513

7. 0.0626

8.

a

Reaction conditions. Substrate: 2.5 mmol; solvent: 1, 2dichloroethane 6 g.; TBHP- 2.5 mmol; catalyst 1A-MoO3/GCMs 10 wt% of substrate; chlorobenzene (internal standard): 15 mmol; reaction temperature: 80 °C; *The remaining products were 1,2, and 5,6-diepoxides. #The remaining products were 1,2, and 9,10diepoxides. The obtained data revealed that 1A-MoO3/GCMs is one of the best among the reported catalysts based on molybdena supported on carbon, with higher catalytic activity in terms of conversion and selectivity.


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The best catalyst, i.e., 1A-MoO3/GCMs was used under optimized reaction conditions to test for the catalyst reusability by stopping the epoxidation reaction of cyclooctene at lower substrate conversion (~80%). After each reaction cycle, the catalyst was separated by filtration from the reaction mixture and washed with 1,2-dichloroethane. There was no considerable decrease in the conversion and selectivity for epoxide even after five cycles (Figure 5). The GCM matrix embedding active MoO3 nanoparticles was responsible for the superior catalytic activity of 1AMoO3/GCMs (see HRTEM and STEM images in Figure 2 and 3).

B. To synthesize the 1A-MoO3/BCMs catalyst, the abovementioned procedure was followed with NH4Mo7O26·4H2O (0.03 g) instead. C. To synthesize the 1S-MoO3/BCMs catalyst the abovementioned procedure was followed with Na2MoO4·2H2O (0.03 g) instead. D. To synthesize the 1S-MoO3/GCMs catalyst the abovementioned procedure was followed but with D-glucose (3 g) and Na2MoO4·2H2O (0.03 g). E. To synthesize the 1A-MoO3/GCMs catalyst the abovementioned procedure was followed but with NH4Mo7O26·4H2O (0.03 g). F. Catalyst characterization: All the catalysts were characterized by various physicochemical techniques and details of instruments and methods are given in Supporting Information S1. G. Typical reaction procedure: The liquid phase catalytic epoxidation reaction was carried out in a 25 mL two necked roundbottom flask equipped with a magnetic stirrer and immersed in a thermostat oil bath. The flask was charged with olefin (2.5 mmol), oxidant (2.5 mmol) 5.5 M TBHP in decane, catalyst loadings were taken as 10 wt% of the substrate and dichloroethane (6 g) was used as a solvent and chlorobenzene (15 mmol) internal standard. The samples were withdrawn periodically and analyzed on Agilent 7890B gas chromatograph equipped with a HP-5 column coated with 5% phenyl 95% dimethylpolysiloxane (60 m length, 0.25 mm diameter and 0.25 µm film thicknesses) and a flame ionization detector.

Figure 5. Recycle study of 1-MoO3/GCMs catalyst. Conclusions To conclude, we have used a simple environmentally benign bottom-up route for the synthesis of molybdenum oxide nanoparticles supported on bio-derived carbon microspheres through the hydrothermal carbonization of bagasse and D-glucose as carbon precursors. The carbon spheres were formed by using a hydrolysis and condensation route catalyzed by oxalic acid. The bagasse source led to non-uniform carbon spheres, whereas glucose yielded uniformly shaped carbon spheres. SEM and STEM elemental mapping proved the uniform distribution of MoO3 nanoparticles (0.5-10 nm) over the carbon spheres. TEM analysis showed MoO3 nanoparticles 5-10 nm in size and uniformly distributed over BCMs. In comparison, no separate molybdena nanoparticles were observed in the case of GCMs as they were embedded in GCM matrix. 1A-MoO3/GCMs gave the best results in terms of catalytic activity and selectivity for olefin epoxidation. Recycle studies showed that this catalyst could be reused for up to five cycles without any loss of catalytic activity. Experimental Section All the reagents including ammonium heptamolybdate (AHM) (S. D. Fine chemical India) and sodium molybdate (Molychem India ltd.), cyclooctene, cyclohexene, D-glucose and 5.5 M TBHP in decane (Aldrich India), oxalic acid (Ranchem, India), ethanol (cymprangludt BV) and bagasse of sugarcane (from local sugar mills, India) were purchased and used without further purification. A. In a typical synthesis, 150 mL Teflon coated closed pressure reactor was charged with finely powered 3 g bagasse, 1 g oxalic acid, 0.3 g ammonium heptamolybdate and 100 mL deionised water. Subsequently, autoclave was kept in furnace for 12 h at 180 °C. After completion of reaction, the reactor was cooled to room temperature and reaction mixture was filtered through Whatman filter paper. The residue was washed with water and ethanol– water mixture (1:1). The final solid was dried at room temperature. The product was abbreviated as 10A-MoO3/BCMs.

ASSOCIATED CONTENT Supporting Information Details on the preparation of the samples, complete description of the XPS, SEM, TEM, STEM characterization tools and detailed catalytic results are available in Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org.”

AUTHOR INFORMATION Corresponding Author Dr. A. V. Biradar; Email: [email protected]

Present Addresses $

Inorganic Material and Catalysis Division, CSIR-Central Salt and Marine Chemical Research Institute, Bhavnagar 364002, Gujarat, India. ‡ Academy of Scientific and Innovative Research, ACSIR, Anusandhan Bhawan, New Delhi-110 001, India. Notes The authors

declare

no

competing

financial

interest.

ACKNOWLEDGMENT AVB acknowledges the Director CSIR-NCL for providing QHS, in-house project MLP 028026 and SERB (DST) Government of India for fast tract project no SERB/F/6598/2013-14. Authors are thankful to Dr A. Das Director, CSMCRI Bhavnagar for kind approval to carry out this work and Dr S. Neogi, for BET surface area measurements and Ondrej Tomanec for HRTEM images. CSIR-CSMCRI Communication No. 141/2016.

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Environmentally Benign Bio-derived Carbon Microspheressupported Molybdena Nanoparticles as Catalyst for the Epoxidation Reaction Dhananjay S. Doke, Shubhangi B. Umbarkar, Manoj B. Gawande, Radek Zboril, Ankush V. Biradar Synopsis: Abundantly available bagasse and D-glucose were directly used as carbon source for catalyst synthesis by using low temperature hydrothermal method



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Environmentally Benign Bioderived Carbon Microspheres-Supported

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