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Presented by M. G. PRAKASH National Centre for Catalysis Research

Nickel based bimetallic catalysts supported on titania for selective hydrogenation of cinnamaldehyde. Presented by M. G. PRAKASH National Centre for Catalysis Research Indian Institute of Technology, Madras. Introduction

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Presented by M. G. PRAKASH National Centre for Catalysis Research

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  1. Nickel based bimetallic catalysts supported on titania for selective hydrogenation of cinnamaldehyde Presented by M. G. PRAKASH National Centre for Catalysis Research Indian Institute of Technology, Madras

  2. Introduction • Bimetallic catalysts - composed of two metal elements in either alloy or intermetallic • form often develop as materials of new category with catalytic properties different • from monometallic catalysts. • Generally bimetallic alloys in particular , is an import subject for a number of • technological reasons some of which are • (1) Catalyst Chemistry (2) Electrochemistry (3) Metal-Metal Interfaces (4) Microelectronic • Fabrication etc. • The following aspect of an alloy surface should be examined , • The chemical composition of an alloy surface • The surface structure factor • The electronic structure and geometric factors

  3. Fig A hypothetical situation of (100) surfaces of an alloy XY with the fcc structure (a) Pure X (b) 50 % X , 50 % Y , ordered (C) 50 % X, 50% Y with Clustering of Y (d)75% X,25 % Y Nieuwenhuys, The chemical physics of Solid Surface Amsterdam 1993, 6 185-22

  4. Schematic illustration of producing crown jewels structure X.Liu, D. Wang and Y.Li Nano Today(2012) ,7 448-466

  5. Objectives • To prepare Nickel Nano particles by using green chemistry via glucose as reducing agent, supported on P25 . • Preparation of bi-metallic Ni-Cu/TiO2, Ni-Ag/TiO2 and Ni-Au/TiO2 catalysts. • Optimization of the reduction conditions for the prepared catalysts. • Studying the Physico-chemical properties of the catalyst samples using various techniques like XRD, TPR, TEM etc. • Studying the catalytic activity of the reduced catalysts using model reactions, liquid phase hydrogenation of cinnamaldehyde. • Identifying the reaction products using GC. • Establishing correlations between the activity, stability and selectivity of the catalysts and their Physico-chemical properties .

  6. Reaction scheme Olefinic group Carbonyl group G = 118 KJ/mol G = 80.71KJ/mol Desired rex Desired product undesired rex undesired rex G = 37.79 KJ/mol G = 0.49KJ/mol CAL=cinnamaldehyde, COL=cinnamyl alcohol, HCAL= hydrocinnamaldehyde, HCOL=hydrocinnamyl alcohol

  7. Aim and scope of the work Experimental approach • To prepare, characterize and test performance of following catalysts • Influence of preparation Methods (Bimetallic catalysts) • Direct Impregnation Method • Urea Deposition method • Impregnation of stabilzed Ni Nano particles • (a)hydrazine hydrate (b) glucose (green chemistry)

  8. Preparation of Bimetallic Cataslyst 0.03 moles of Nickel acetate + 0.03 moles of Cu or Ag or Au + 40 ml of D-glucose solution (0.1 M) Stirred for 30 min at RT 10ml of liq.ammonia solution Refluxed for 5 h at 80⁰ C The solution was changed black colour 1g of TiO2 ( P25) Stirred for 2 h at 80⁰ C Cooled , centrifuged and dried at 60⁰ C

  9. M .Vaseema,N.Tripathya G. Khangbandb Y.Hahn*aRSC Adv., 2013, 3, 9698–9704

  10. Fig .1 shows the XRD patterns of (a) Ni/P25 (b) Ni-Cu/P25 (c)Ni-Ag/P25 (d)Ni-Au/P25

  11. Fig .2 shows the TPR profile of (a) Ni/P25 (b)Ni-Cu/P25 (c)Ni-Ag/P25 (d)Ni-Au/P25

  12. Fig .3 shows the TEM Images are (a) Ni/P25 (b)Ni-Cu/P25 (c)Ni-Ag/P25 (d)Ni-Au/P25

  13. Fig.4Hydrogenation of cinnamaldehyde on Ni/P25 ,Ni-Cu/P25,Ni-Ag/P25and Ni-Au/P25 conversion and selectivity. Reaction temperature 373 K ,Time 1 h ,catalyst 150 mg, cinnamaldehyde 1.2 g reactant.

  14. Table.1. Hydrogenation of cinnamaldehyde on Ni and Ni based bimetallic catalysts on TiO2 supports at different temperatures

  15. Calibration of GC Mixture of reactant and products HCOL HCAL COL Reactant

  16. Concept of Lewis sites C=O bond activation by electropositive Fe on Pt surface Ref: Richard, J. Ockelford, A. Giroir-Fendler, and P. Gallezot, Catal.Lett., 3,53 (1989).

  17. Summary • Conculsion • Ni-Au/P25,Ni-Cu/P25 & Ni-Ag/P25 bimetallic systems are showing more activity and selectivity, but when compared to monometallic Ni/P25. • The strong interaction between Ni and Cu or Ag or Au was demonstrated to the main reason for the enhanced catalytic activity of catalysts. • The Electronic structure of the surface Ni atoms was modified upon the addition of Cu or Ag or Au ,so reducibility of nickel increased. • Improved the activity can be also ascribed to the high dispersion of Cu or Ag or Au on nickel nanoparticles of the bimetallic catalysts.

  18. HYDRGENOLYSIS OF BIO-MASS DERIVED POLYOLS TO VALUE ADDED CHEMICALS R.Vijaya Shanthi,S.Sivasanker National Centre for Catalysis Research, I I T – M, Chennai.

  19. Introduction • One of the most attractive routes of biomass utilization is its direct conversion to valuable organic compounds which gets more and more attention an ever . • An effective process for the biomass utilization is hydrogenolysis of polyalcohols derived from biomass. • Hydrogenolysis has a great potential in the conversion of biomass-derived polyols, such as sugars or sugar alcohols.

  20. Present work • We had earlier reported studies on Ni, Pt and Ru supported on the basic support, NaY for sorbitol hydrogenolysis. (Topics in Catalysis (2012) 55:897–907.) • As a part of our investigations on the influence of the support on the performance of supported metal catalysts we have now carried out hydrogenolysis of glucose & glycerol over unconventional support, viz. Hydroxyapatite • Materials based on Ca10(PO4)6(OH)2 (hydroxyapatite, HAP) have attracted tremendous interest because of high stability at high temperatures and least soluble in aqueous medium which will be very useful for reactions involving aqueous medium . • Taking into account environmental and economical considerations, the handling of hydroxyapatite used as a catalyst presents many advantages such as to easier separation,recovery from the reaction mixture and thus, enhanced recycling possibilities, which are now well established in fine organic synthesis. • HAP has recently received much attention in view of its potential usefulness as adsorbent and most importantly as catalyst in solid/gas reactions.

  21. The various products obtainable by hydrogenolysis of glucose Crystalline structure of hydroxyapatite

  22. Synthesis of HAP & preparation of catalysts 7.927g of (NH4)2HPO4 in 250ml solution( at a pH>12 (60–70 ml NH4OH) )+ 23.63 g of Ca(NO3)2 .4H2O in 150ml solution stirred at room temperature refluxed for 4 h Filtered, dried for 12 h at 120 °C Calcined in air at 600 °C for 4 h Support HAP Impregnation method- (Ni -6 wt.%;Pt-1 wt.%;Ru-1 wt.%) dried for 12 h at 120 °C Calcined in air at 600 °C for 4 h Reduced in H2 for 4 h at 400 °C (prior to use) 6%Ni/HAP;1%Pt/HAP;1%Ru/HAP Catalyst

  23. Characterization of HAP & the catalysts Physicochemical property XRD patterns TEM images - The crystals are rod-like in shape & the particles are of approximately 20–40 nm in diameter with 40–60 nm in length.

  24. Glycerol hydrogenolysis over metal loaded HAP Effect of temperature – 12%Ni/HAP Effect of catalysts Conditions: 15% glycerol in water; press.: 60 bar; time: 6 h; stirring speed: 300rpm; G= glycerol; PD = 1,2-propanediol & EG = ethylene glycol; A-absence of base; B-presence of base

  25. Effect of solvent– 12%Ni/HAP Recyclability – 12%Ni/HAP The presence of base enhances the conversion & selectivity

  26. Glucose hydrogenolysis over metal loaded Hap Conditions: 15% glucose in water; cat.: 0.2 g; temp.: 140 °C; press.: 60 bar; time: 6 h; stirring speed: 1000 rpm; S = Sorbitol; G= glycerol; PD = 1,2-propanediol & EG = ethylene glycol; trihydric(except glycerol) and higher alcohols; monohydric alcohols and :others (methanol,ethanol&butanol); Ca(OH)2 , 0.25g. Order of activity: (A) Ni/Hap > Ru/Hap > Pt/Hap (in absence of Ca(OH2). (B) Ni/Hap > Ru/Hap > Pt/Hap (in presence of Ca(OH2).

  27. Effect of reaction parameters – 6%Ni/HAP Catalyst amount Temperature Effect of catalysts Effect of run duration – 6%Ni/HAP • Temp - 140 °C; • Catalyst - 0.2g • Run duration – 6 h Optimum conditions

  28. Recyclability – 6%Ni/HAP (A) in the absence of Ca (OH)2and (B) in the presence of Ca(OH)2 Conditions: Temp., 140 °C; pressure, 60 bars; run duration, 6 h; catalyst, 0.2g; sorbitol, 15 g; water, 85 g; Ca(OH)2 , 0.25g. The presence of base enhances the conversion & selectivity marginally

  29. Conclusion The influence of the support on Hydrogenolysis of glycerol & glucose was investigated over HAP metal supported catalysts. The loading of the metals was: Ni, 6%; Cu, 6 %; Ru 1 %; and Pt, 1 %. Ni/HAP & Ni/Hap were found to be the most active and selective (for glycols) amongst all the catalysts. The influences of temperature, catalyst loading and reusability on sorbitol conversion and selectivity were investigated with 6%Ni/HAP catalyst. The influence of the addition of the base Ca(OH)2 on conversion and product yields is also influenced the conversion and selectivity of both glycerol & glucose.

  30. THANK YOU

  31. A general observation is that the reaction proceeds better in a basic medium, typically, in the presence of Ca(OH)2. Mechanism of the hydrogenolysis of sorbitol in the presence of a base

  32. Photocatalytic reduction of Carbon dioxide over Strontium titanate surfaces V. Jeyalakshmi, K. R. Krishnamurthy & B. Viswanathan NCCR, IIT Madras

  33. Utilization of CO2 - A global endeavor • Global demand for energy to set to increase by 50 % by 2030 • Fossil fuels continue to be the major source of energy

  34. Utilization of CO2 - A global endeavor • Increase in CO2 emission levels- a matter of concern • Increase in earth’s average surface temp. - 0.6K in the last century • Green house effect, changes in weather patterns CO2 management - A challenging task

  35. Processes for CO2 conversion Chemical Photo-chemical Bio-chemical Photo bio-chemical Radio-chemical Electro-chemical Photo electro-chemical Photo bio-electrochemical (MA Scibioh & B.Viswanathan Proc.Ind.Natl. Sci.Acad.70A,407,2004)

  36. Photo catalytic reduction of CO2 with H2O Process & catalyst • Splitting of water to yield hydrogen • Reductive conversion of CO2to hydrocarbons • Both steps proceeding via photo catalysis. • Bi-functional catalyst design to include components that are • active for both functionalities • suitable for activation with the most abundant visible light Challenges for practical application • Maximization of hydrocarbons formation • Selectivity towards narrow range hydrocarbons

  37. Choice of catalysts- Guiding principles Valence band top energy level to be suitable for splitting of water Conduction band bottom energy level to be more negative with respect to reduction potential of CO2 VB & CB potentials for selected semi-conductors relative to the energy levels for CO2 redox couples in water (T.Inoue, A.Fujishima,S.Konishi & K.Honda, Nature,277,637,1979)

  38. SrTiO3, Sr3Ti2O7 &Sr4Ti3O10 • SrTiO3, as one of the most promising photocatalysts, is now used in various practical applications. • In these materials , slabs of SrTiO3 are cut parallel to the idealised cubic perovskite (100) planes and stacked together , each slab being slightly displaced from the process. Kudo et al. Chem. Soc. Rev., 38(2009) 253

  39. CO2 Photo reduction on Strontium titanate surface The large band gap sizes of early transition-metal oxides (>3.0eV) restrict their photocatalytic activities to ultraviolet wavelengths.

  40. Modified Strontium titanate catalysts • Non metal doping (N doping) • Metal doping (Fe doping) • (a) the charge carrier recombination time is largely influenced by the presence of iron cations, (b) presence of iron induces a batho-chromic effect, and (c) iron doped photocatalyst is efficient in several important photocatalytic reduction and oxidation reaction • STO:N, Fe. Will exhibit high photocatalytic activities under vis illumination, which is due to the decrease in the oxygen vacancies because co doping maintains the charge balance.

  41. Synthesis of SrTiO3 Polymerized complex method gives fine and well-crystalline powders with a high surface area at relatively low calcination temperature and short calcination time compared with a conventional solid state method. Kudo et al. Chem. Soc. Rev., 38(2009) 253–278

  42. Preparation of Strontium titanate Ethylene glycol : Methanol(1:2). 2 mole of C16H36O4Ti was added. 0.5mole of Citric acid + 3mole of Sr(NO3)2 + 2mole of Urea/Thiourea or 3% Fe2O3 added to the mixture . The solution was stirred at 130°C for 20 hrs. The resulting polymerized complex gel was pyrolyzed at 350 °C Precursor was calcined at 900°C for 2 h. N,S/Sr3Ti2O7 or Fe2O3/Sr3Ti2O7 Methanol, Ethylene glycol , citric acid should be in the molar ratio of 1:2:0.5. H.Jeong et al. International Journal of Hydrogen Energy 31 (2006)1142 – 1146

  43. XRD pattern for SrTiO3 The shift indicates that a part of Iron at least is homogeneously doped into the SrTiO3 lattice. Ionic radii of six-coordinated Fe3+ (0.62A˚) are almost the same as Ti4+ ion (0.61A˚).

  44. XRD pattern for Sr3Ti2O7 The shift indicates that a part of Iron at least is homogeneously doped into the Sr3Ti2O7 lattice. Ionic radii of six-coordinated Fe3+ (0.62A˚) are almost the same as Ti4+ ion (0.61A˚).

  45. XRD pattern for Sr4Ti3O10 The shift indicates that a part of Iron at least is homogeneously doped into the Sr4Ti3O10 lattice. Ionic radii of six-coordinated Fe3+ (0.62A˚) are almost the same as Ti4+ ion (0.61A˚).

  46. DR spectra for the catalysts

  47. Photo luminescence spectra of the catalysts Co doping increases exciton life time.

  48. SEM Image SrTiO3 Sr3Ti2O7 Sr4Ti3O10 Fe NS Sr4Ti3O10 Fe NS SrTiO3 Fe NS Sr3Ti2O7

  49. Reaction & Analysis • Reactor volume - 650 ml • Reaction medium - 400 ml of 0.2 N aqueous NaOH. • Temperature- 298K • Catalyst loaded - 0.4g. Dispersed in the medium with continuous agitation-400 rpm • CO2 was bubbled for 30 min. • pH of the medium- Reduced to 8.0 after saturation with CO2 from the initial value 13.0 • Reaction medium was irradiated through a 5cm dia. quartz window. • Light source-High pressure Hg lamp-UV-Vis radiation -300-700 nm • 77W power • The products were analyzed using Perkin Elmer Clarus 500 Gas chromatograph - Poroplot Q, 30 m, at 150ºC with FID for analysis of hydrocarbons and Mol.Sieve 5A column for H2 & O2 analysis • Gas (0.2 ml) and liquid (1 µl) phase samples were withdrawn every two hours from the reactor and injected into the GC.

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