Batches of 1 kg of VAlO(3) & BiMo(4) Understanding the role of shaping in the preparation of heterogeneous catalysts: graphite as tableting agent Víctor G. Baldovino-Medranoa,*, Minh Thang Leb, E. Bruneelc, Isabel Van Driesschec, B. Farina, Eric M. Gaigneauxa,* aUniversité catholique de Louvain, Institute of Condensed Matter and Nanosciences - IMCN, Division « MOlecules, Solids and reactiviTy – MOST », Croix du Sud 2, box L7.05.17, B-1348 Louvain-la-Neuve, Belgium bDepartment of Petrochemistry, Hanoi University of Technology, Dai Co Viet Street 1, Hanoi, Vietnam cDepartment of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium *vigabalme@gmail.com / eric.gaigneaux@uclouvain.be Objective Conclusions Graphite as tableting agent of VAlO and BiMo: Acts as a lubricant for the process: It forms a layer between the tablets and the die of the tableting machine which is necessary for continuous production. Is an effective binding agent: It increases the mechanical resistance to compression of the tablets Affects surface area (SABET) as follows: Positive for non-porous BiMo (increase in SABET) Negative for mesoporous VAlO (decrease in SABET) Modifies the catalytic performance: It favored ODHP for calcined VAlO  Good guy It disfavored catalytic performance for non-calcined VAlO and BiMo  Necessary evil To analyze the role of graphite as a shaping agent for vanadium-aluminium mixed (hydr)oxides (VAlO) and bismuth molybdates (BiMo)  VAlO and BiMo are Selective oxidation catalysts. Catalyst shaping is Context Necessary in industry Seldom studied in catalysis science(1) Commonly done by Tableting Graphite as additive is a “necessary evil”(2) poorly understood Experimental Catalyst preparation Catalytic tests Characterization Analysis of reaction products: On-line GC TCD and FID detectors to quantify the reaction products: O2, C3H8, C3H6, C3H4O and COx. Expression of the results Intrinsic conversion and yield Xj = molar conversion Yj = molar yield j = C3H8 or C3H6 w = catalyst mass (g) SABET = BET surface area (m2×g-1) Performed in every stage of the process: Before and after tableting For fresh and spent catalysts 500 mm > Dp ≥ 350 mm, VAlO-xG-NC/C 400 mm > Dp ≥ 250 mm, BiMo-xG-NC Grinding & Sieving + Batches of 1 kg of VAlO(3) & BiMo(4) Sieved to particles size ≤ 100 mm Graphite (G) x = 0, 1, 3, 7 wt.% 4h VAlO-xG-NC VAlO-xG-C Method: co-precipitation VAlO (hydroxide) BiMo (oxides) Mechanical strength for tablets Axial tensile strength (σZ) Instron 5566 machine Physisorption (N2 & Kr) at 77K Surface Area (SBET) & Porosity Micromeritics Tristar and ASAP 2010 Textural properties SEM Microscopy JSM-35 C, JEOL Chemical state XPS SSI-X-probe spectrometer Crystallinity XRD D8 Brüker Advanced diffractometer Molecular structure Raman InVia apparatus from Renishaw Oxidative dehydrogenation of propane (ODHP) for VAlO-xG-NC/C Nomenclature VAlO-xG-NC BiMo-xG-NC NC = non calcined Gas Flow: 40 mL/min C3H8/O2/N2= 10/15/75 (vol %) T = 748 K Propylene oxidation to acrolein for BiMo-xG-NC Mixing “Rolling bottle” Tableting Hand operated machine Tablets L = 2.3 mm ϕ = 5.1 mm Gas Flow: 59 mL/min C3H6/O2/N2= 2.5/2.5/95 (vol %) T = 698 K Patm Fixed-bed continuous reactor Results & Discussion Effect of graphite on the tableting process Effect on the mechanical resistance and SABET Chemical state of the catalysts A continuous process for tableting of VAlO and BiMo was not possible without graphite + Graphite VAlO-xG-NC Graphite was a lubricant that formed a shiny layer on the rim of the tablets BiMo-xG-NC Upon calcination: VAlO-xG-C tablets cracked due to water release not to graphite burning Graphite was evenly distributed within the catalyst particles SEM image of BiMo-xG-NC particles 1 wt.% Graphite was enough to boost the mechanical resistance of the catalysts SABET increased for BiMo  non-porous material SABET decreased for VAlO  mesoporous material  Changes in surface area can be associated to pore widening during tableting Surface area of VAlO-xG-NC and BiMo-xG-NC catalysts Mechanical resistance of VAlO-xG-NC and BiMo-xG-NC BiMo-xG-NC XPS C 1s spectra for VAlO-xG-NC/C (fresh & spent) BiMo-xG-NC Except for the presence of the graphite, C-C component, no apparent changes in the chemical state of the catalysts (VAlO-xG-NC/C & BiMo-xG-NC) was observed Graphite effect on the catalysts structure Effect on the catalytic performance XRD analysis of BiMo-xG-NC (fresh & spent) Raman spectra of VAlO-xG-NC/C Catalytic performance of VAlO-xG-NC/C in ODPH Graphite band The structure of VAlO-NC/C was modified by calcination but not by the presence of graphite For calcined VAlO-xG-C graphite was a promoter No variation in the XRD pattern of BiMo No variation in the XRD pattern of BiMo-xG-NC Catalytic performance of VAlO-xG-NC in ODHP Catalytic performance of VAlO-xG-C in ODHP Conclusion Graphite did not induce molecular level effects on the structure of the catalysts Graphite had a negative effect on non-calcined catalysts; VAlO-xG-NC and BiMo-xG-NC Acknowledgements Authors acknowledge the financial support of Fonds Speciaux de Recherche (UCL), the Marie Curie Actions of the EU-FP7 and the “DGTRE, Région Wallonne”, project “DEPOLAIR” Convention No. 1217556. M.T. Le thanks the Vietnam National foundation for Science and Technology (NAFOSTED) for funding (Project No104.03-2011.16) Calcination of VAlO-xG-NC could have caused the formation of oxygen functional groups favorable to ODHP References Catalytic performance of BiMo-xG-NC in propylene oxidation to acrolein (1) S. Mitchell, N.-L. Michels, J. Pérez-Ramírez, Chem. Soc. Rev. 42, 6094 (2013) (2) A.B. Stiles, T.A. Koch, in Chemical Industries, Catalyst Manufacture 2nd ed., Marcel Dekker (1995) pp. 87-88 (3) V.G. Baldovino-Medrano, B. Farin, E.M. Gaigneaux, ACS Catalysis 2, 322 (2012) (4) V.G. Baldovino-Medrano, M.T. Le, I. Van Driessche, E. Bruneel, E.M. Gaigneaux, Ind. Eng. Chem. Res. 50, 5467 (2011)