World Biodiesel Congress and Expo Novel perovskite type hydroxides and their oxide derivatives as solid acid-base catalysts for biodiesel synthesis and byproduct glycerol transformations Dr. Ganapati Shanbhag Materials Science Department Poornaprajna Institute of Scientific Research Devanahalli, Bengaluru, INDIA

Outline of the talk Introduction Catalyst preparation Catalyst characterization Previous literature Transesterification of vegetable oil Fuel properties of synthesized biodiesel Reusability studies Glycerol transformations to valuable chemicals Transesterification of glycerol with methyl acetate Carbonylation of glycerol with urea Summary and conclusions

Advantage of using Biodiesel Does not produce explosive vapors. Has a relatively high flash point (close to 1500C). Transportation, handling and storage are safer than with conventional Diesel . Due to the presence of oxygen, amount of carbon monoxide (CO) and unburnt hydrocarbons in the exhaust is reduced. The important aspect of the biodiesel is that it gives comparatively more milage and less smoke when used, making it eco friendly.

Advantage of using solid catalyst

Matal hydroxystannate Compounds name as Burtite. Layered hydroxides. Metal atoms are octahedrally coordinated with oxygen atoms to form Sn(OH)6 and Ca(OH)6 polyhedra. Polyhedra share ‘‘O’’ corners to build the structural framework. Synthesized by co-precipitation method. “Ca2+“ replaced with Mg, Zn, Sr to form respective stannates.

Metal hydroxystannate Preparation Ca2+ Aq. NaOH till pH 14 Stirred at Room Temp CaSn(OH)6 Sn4+ Co-precipitation CaSn(OH)6 ZnSn(OH)6 MgSn(OH)6 SrSn(OH)6 S. Sandesh, A.B. Halgeri, G. V. Shanbhag, RSC Advances, 2014, 4, 974-977

CaSn(OH)6 FT-IR PXRD TGA SEM

Transesterification of Vagetable oil and glycerol

KF loaded nano-y-alumina Research on Biodiesel synthesis OIL SOURCE CATALYST TEMP MeOH: OIL CATALYST (WT %) Oil conversion (%) Cotton seed oil KF/MgLa 65 12:1 5 98 Jatropha Mg/Zr Soyabean oil KF/ZnO 90 10:1 3 87 Pongamia oil Mg-Al 6:1 2 Sunflower Oil KF loaded nano-y-alumina 15:1 Sunflower oil Cao 60 13:1 1 Tallow seed oil KF/CaO 96 La/CaO 20:1 94 Canola oil KOH loaded on Alumina 89 Mg-Al hydrotalcites 8 67 Sunflower oil & waste cooking oil CaO 80 92/84 Egg shells (CaO) 95 72 KF/Zn(Al)O 97 CaO /Li2CO3 6 99

Catalytic activity of different catalysts Calcined temp (°C) Basicity (HI) µmol/g a =nile blue b =phenolphthalein Conversion (%) Biodiesel Yield (%) CaSn(OH)6 150 7a/22b 96 94 MgSn(OH)6 11a/23b 92 90 CaSn oxide (600) 600 3a/18b 88 87 ZnSn(OH)6 33b 72 70 SrSn(OH)6 3a/15b 65 63 KF/CaO 5a/24b 90.3 89 HTc (Mg/Al) 200 26 b 86 84 Ca(OH)2 19b 82 48 CaO 850 18b 74.2 MgO 13b 70.8 68 Reaction conditions: Oil: MeOH= 1:10, Catalyst amount = 3 wt%, Temperature = 65 °C, Time = 3 h. Basicity- indicator method G. V. Shanbhag et al, Applied Catalysis A, 523, 2016, 1-10

Transesterification of edible and non edible oil with CaSn(OH)6 catalyst Before esterification (AV) After esterification (AV) Reaction Time (h) Conversion (%) Sunflower 0.2 - 3 96 WCO 1.5 4 97 Honge 7.5 1.3 9 92.8 Simaraouba 8.5 0.78 14 94.6 Jatropha 14.3 0.99 11 95.8 Reaction conditions: Oil: MeOH= 1 : 10, Catalyst amount = 3 wt%, Temperature = 65 °C.

Fuel properties of synthesized Biodiesel SF WCO Honge Simarouba Jathropha BIS IS15607 ASTM D6751 DIN EN14214 Specific gravity @ 20 °C, kgm-3 0.81 0.88 0.875 0.885 0.86-0.9 - Viscosity @ 40 °C, mm2s-1 2.85 4.25 4.18 4.75 4.62 4.77 2.5-6.0 1.9-6.0 3.5-5.0 Flash point, °C 52 165 118 174 178 180 >120 >130 Fire point, °C 170 128 182 194 189 Ash content, % 0.01 0.012 0.011 <0.02 *Measurements at Reva University, Bangalore

Reusability test of CaSn(OH)6 Reaction conditions: Oil: MeOH= 1 : 10, Catalyst amount = 3 wt%, Temperature = 65 °C.

Transesterification of glycerol with methylacetate Catalysts Glycerol conversion (mol %) Selectivity to Diacetin (mol%) Selectivity to Monoacetin (mol%) CaSn(OH)6 78.2 32.6 67.3 MgSn(OH)6 65.4 33.8 66.1 CaSn-Oxide (600°C) 56.6 22.8 77.1 ZnSn(OH)6 40.0 37.5 62.5 SrSn(OH)6 25.2 30.2 70.1 KF/CaO 69.0 32.9 65.3 HTc (Mg/Al) 68.5 13.5 86.1 Ca(OH)2 52.1 12.9 87.1 CaO 47.2 9.60 90.2 MgO - 99.8 Reaction conditions: Glycerol: methyl acetate=1:10, Catalysts amount = 7 wt %, Temperature = 30 °C, Time = 2 h

Carbonylation of glycerol using urea to produce glycerol carbonate 15 Biomass Glycerol carbonate is formed when two adjacent hydroxyl groups of glycerol undergo condensation with urea .

Uses of Glycerol carbonate

Glycerol conversion (mol%) Glycerol carbonate selectivity (mol%) Catalytic activity of different catalysts Catalyst Glycerol conversion (mol%) Glycerol carbonate selectivity (mol%) Blank 0.1 99.9 ZnSn(OH)6 98 99.6 ZnSn oxide 64 99.2 CaSn(OH)6 90.5 92 MgSn(OH)6 86 98.8 ZnO 30.6 SnO2 30.2 99.4 Sn(OH)4 46.8 MgO 12.6 99 CaO 20.2 HTc (Mg/Al) 10 HTc (Zn/Al) 65 99.5 Reaction conditions: Glycerol: Urea; 1:1; Catalyst weight = 5 wt% temperature = 165 °C, N2 bubbling, Time = 5 h. S. Sandesh, A.B. Halgeri, G. V. Shanbhag, RSC Advances, 2014, 4, 974-977

Comparison with the literature Catalyst Temp (°C) Reaction time (h) Glycerol conv (%) carbonate (%) Selectivity Yield SW21 140 4 52.1 95.3 49.7 Sn-beta 145 5 70.0 37.0 25.9 Zr-P 3 80.0 100 Au/Fe2O3 150 48.0 38.4 2.5% Au/Nb2O5 66.0 32.0 21.1 Sm0.66TPA 49.5 85.4 42.3 Zn1TPA 69.2 99.4 68.8 ZnSn(OH)6 165 98.0 99.6 97.6 La2O3 68.9 98.1 67.6

Carbonylation reaction of glycerol with urea

Catalyst reusability XRD pattern of recycled catalyst

Zinc-tin composite oxide The presence of Mm+On- ion pairs in metal oxides, it is found to exhibit acid-base properties. The lattice oxygen present on the metal oxide surface are considered to act as Lewis basic sites. Metal oxides containing more than one phase is said to be Composite metal oxides. Composite metal oxides are more active than the individual oxides due to its co- operative effect.

Catalyst preparation methods Co-precipitation Evaporation Solid state P. Manjunathan, R. Ravishankar, G. V. Shanbhag, ChemCatChem, 2016, 8, 631-639

XRD patterns of Zn-Sn composite oxide 23 Zn/Sn mole ratio of 2 Zn/Sn mole ratio of 1 Formation of ZnO, SnO2 and little spinel Zn2SnO4 with SS and Evp Spinel Zn2SnO4 with Co-precipitation method, due to dehydroxylation of metal hydroxides

XRD patterns of Zn-Sn composite oxide 24 Effect of different calcination temperature Zn/Sn mole ratio from 1 to 3

Physico-chemical properties of catalysts Calcination Temp (°C) SBET [a] (m2/g) Pore volume [b] (cm3/g) Pore size [c] (nm) Acidity (µmol NH3/g)d Basicity (µmol CO2/g) e Total active sites (µmol/g)f ZnO 600 18.9 0.022 4.6 60 12 72 SnO2 16.6 0.066 15.8 30 4 34 Zn2SnO4 40 0.15 3.7 160 20 180 Zn1Sn-CoPre 13.3 0.056 17 235 52 287 Zn2Sn-CoPre 15.2 0.049 12.6 268 61 329 Zn3Sn-CoPre 16.9 0.046 10.9 256 48 304 Zn1Sn-SS 8.9 0.055 24.7 216 38 254 Zn2Sn-SS 9.2 0.050 22.7 223 45 Zn1Sn-Evp 31.5 0.132 16.7 181 35 Zn2Sn-Evp 33.2 0.130 16.5 210 258 [a] BET surface area, [b] Total pore volume, [c] Average BET pore diameter [d] NH3-TPD, [e] CO2-TPD, [f] sum of acidity and basicity

Total active sites (µmol/g)f Physico-chemical properties of catalysts Catalyst Calcination Temp (°C) SBET [a] (m2/g) Pore volume [b] (cm3/g) Pore size [c] (nm) Acidity (µmol NH3/g)d Basicity (µmol CO2/g) e Total active sites (µmol/g)f Zn2Sn-CoPre 500 25 0.052 8.4 207 30 237 600 15.2 0.049 12.6 268 61 329 700 14.1 0.047 13.2 240 53 293 800 6 0.024 16.3 155 27 182 1000 3 0.007 9.3 100 7 107 [a] BET surface area, [b] Total pore volume, [c] Average BET pore diameter [d] NH3-TPD, [e] CO2-TPD, [f] sum of acidity and basicity

PS= Particle size, APS = Average particle size SEM images of Zn-Sn composite oxides Zn1Sn-Evp Zn1Sn-SS Zn1Sn-CoPre PS= 2 to 30 µm (APS = 8.3 µm) PS= 0.4 to 1.6 µm (APS = 0.8 µm) PS= 0.5 to 4 µm (APS = 1.6 µm) Zn2Sn-CoPre Zn3Sn-CoPre Zn2Sn-CoPre PS= 0.8 to 2.5 µm (APS = 1.6 µm) PS= 0.9 to 2.5 µm (APS = 1.7 µm) PS= Particle size, APS = Average particle size

TEM and HR-TEM images of Zn2Sn-CoPre-600 28 TEM and HR-TEM images of Zn2Sn-CoPre-600: (a) and (b) TEM image; (c) HR-TEM of cubic particles; (d) TEM image of secondary particles; (e) HR-TEM of green circled portion of image (d); (f) HR-TEM of yellow circled portion of image (d). Zn2SnO4 (311) (220) (110) (110) e f (100) SnO2 ZnO

Carbonylation of glycerol using urea to produce glycerol carbonate

Catalytic activity studies Catalyst Total active sites (µmol/g) Glycerol conversion (wt%) Glycerol carbonate selectivity (wt%) Glycerol carbonate yield (wt%) Blank - 32 95.8 30.6 ZnO 72 66.4 98.1 65.1 SnO2 34 39.6 99 39.2 Zn2SnO4 180 50 96 48 Zn1Sn-CoPre-600 287 88 99.2 87.3 Zn1Sn-SS-600 254 79.5 99.4 79 Zn1Sn-Evp-600 216 76.1 75.5 Reaction conditions: Glycerol = 2 g, Urea = 1.31 g, catalyst = 0.33 g, temperature = 155 °C, time = 4h, under N2 bubbling

Catalytic activity studies Catalyst Total active sites (µmol/g) Glycerol conversion (wt%) Glycerol carbonate selectivity (wt%) Glycerol carbonate yield (wt%) Zn1Sn-CoPre-600 287 88 99.2 87.3 Zn2Sn-CoPre-600 329 96 99.6 95.6 Zn3Sn-CoPre-600 304 90.7 98.7 89.5 Zn2Sn-SS-600 268 84 83.3 Zn2Sn-Evp-600 258 80 99 79.2 Reaction conditions: Glycerol = 2 g, Urea = 1.31 g, catalyst = 0.33 g, temperature = 155 °C, time = 4h, under N2 bubbling

Effect of calcination temperature of most active Zn2Sn-CoPre catalyst on catalytic activity Reaction conditions: Glycerol = 2 g, Urea = 1.31 g, catalyst = 0.33 g, temperature = 155 °C, time = 4h, under N2 bubbling

Reusability studies of Zn2Sn-CoPre-600 catalyst Reaction conditions: Glycerol = 4 g, Urea = 2.62 g, temperature = 155 °C, catalyst = 0.66 g, time = 4 h, under N2 bubbling

Characterization of spent Zn2Sn-CoPre-600 composite oxide catalyst 34 XRD pattern of fresh and spent catalysts

Summary and Conclusions Metal hydroxystannates were applied as solid base catalysts for the first time. CaSn(OH)6 showed 96 % biodiesel yield for sunflower oil, higher compared to other solid catalysts. CaSn(OH)6 was highly active, reusable catalyst for biodiesel synthesis. Metal hydroxyl stannates showed good performance for transesterification of glycerol with methyl acetate. ZnSn(OH)6 showed high glycerol conversion of 98 % with 99 % glycerol carbonate selectivity and also showed good reusability. Zinc-Tin composite oxide catalysts were synthesized by three different methods viz., co-precipitation, solid state and evaporation and evaluated for the synthesis of glycerol carbonate. Zn-Sn composite oxide prepared from co-precipitation showed excellent catalytic performance compared to other methods. The superior catalytic performance of ZnSn-CoPre catalyst is mainly attributed to the presence of high amount of acidic and basic sites.

Contributors Dr. Vijaykumar Dr. Swetha S. Mr. Manjunathan Materials Science Dept

Thanks for your attention ! I thank the Organisers & Thanks for your attention ! 37