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Compact reactor and carbon supported catalyst system for multiphase air oxidation

Deliverables

MAST's primary target in this project has been to complete the development of the nanoporous synthetic carbon beads that were originally produced on a gram scale in an earlier EU sponsored project and the their structural optimisation. During this project the the production of the polymer beads has moved through lab scale 1kg to 50kg/day batch pilot plant production to a continuous pilot scale unit capable of 2-3 tonnes day. The carbonisation and activation has also moved from small laboratory batch scale processing to a continuous rotary kiln capable of processing >100Kg/day of feed polymer. These have provided the basis for the design of the full-scale production plant that we expect to have in operation within 18-24 months. Whilst the project has been targeted specifically at catalyts support applications, where the materials have shown unique properties, they have also been evaluated in other projects for use in biomedical and adsorbent applications. The overall studies have established that a significant market does exist for these materials that has underpinned our plans for the installation of the full-scale commercial facility. It is our intention that this will be constructed in the UK and will at that stage be the largest synthetic carbon production plant in the world. publications 1)Structural characteristics of activated carbons and ibuprofen adsorption affected by bovine serum albumin, Melillo M, Gun'ko VM, Tennison SR, Mikhalovska LI, Phillips GJ, Davies JG, Lyoyd AW, Kozynchenko OP, Malik DJ, Streat M, Mikhalovsky SV, LANGMUIR 20 (7): 2837-2851 MAR 30 2004 2)The effect of protein binding on ibuprofen adsorption to activated carbons, Melillo M, Phillips GJ, Davies JG, Lloyd AW, Tennison SR, Kozynchenko OP, Mikhalovsky SV CARBON 42 (3): 565-571 2004 3)Assessing the in vitro biocompatibility of a novel carbon device for the treatment of sepsis " Biomaterials, In Press, Corrected Proof, Available online 20 June 2005, Susan R. Sandeman, Carol A. Howell, Gary J. Phillips, Andrew W. Lloyd, J. Graham Davies, Sergey V. Mikhalovsky, Steve R. Tennison, Andrew P. Rawlinson, Oleksandr P. Kozynchenko, Hannah L.H. Owen et al. conferences 1)Middle Molecule Adsorption from Ultrafiltrate for Use in Critical Care Medicine. European Society for Biomaterials, 2001. K.A. Scorgie1, J.G. Davies1, S.V. Mikhalovsky1, A.W. Lloyd1, M.K. Street2, C. Kingswood2 & G.J. Phillips1. 1School of Pharmacy & Biomolecular Sciences, Cockcroft Building, University of Brighton, Lewes Road, Brighton, BN2 4GJ, U.K 2Royal Sussex County Hospital, Eastern Road, Brighton, UK. 2) 2nd Defence Nanotechnology Meeting, London, 2003, Development of nano engineered adsorbents for novel group and personnel protection applications, S Tennison1, M Smith2, B Crittenden3, 1) MAST carbon Ltd, 2) CBDE, Porton Down, 3) Bath University, Department of Chemical Engineering 3) International Carbon Conference, 2003, Adsorption of Lipopolysaccharide (LPS) by Polymer-Based Pyrolysed Carbons and Resins C. Howell1, S. Sandeman1, G. Phillips1, A. Lloyd1, S. Mikhalovsky1, J.G. Davies1, M. Murphy1, M. Melillo1, L. Barnes1, S. Tennison2, J. Courtney3. 1School of Pharmacy and Biomolecular Sciences, University of Brighton, 2Mast Carbon Ltd, Surrey, 3Bioengineering Unit, University of Strathclyde 4)International Carbon Conference, 2004, Application of carbon adsorbents in renal failure treatment, M.Melillo1, G.J.Phillips1, J.G.Davies1, A.W.Lloyd1, S.R.Tennison2, O.P.Kozynchenko2, S.V.Mikhalovsky1, 1 School of Pharmacy and Biomolecular Sciences, University of Brighton, Lewis Road BN2 4GJ, Brighton UK, 2 MAST Carbon Ltd., Henley Park, Guildford, Surrey, GU3 2AF UK
Experiments are performed in a structured packed bed reactor that has been developed for the selective oxidation of organic liquids to produce pharmaceutical products. Molecular oxygen is used as the oxidant, providing a cleaner processing route, than in established methods. The structured assembly consists of an integrated heat exchange system, a gas/liquid mixing zone, and provision for reactant injection. To illustrate the application, the selective oxidation of benzyl alcohol to benzaldehyde was studied. In the first phase of work, experiments are performed with a Ru/Al2O3 catalyst. This enabled the operating characteristics of the reacting system to be established. In the second phase, experiments were performed on a Pt/C catalyst that was selected by the project partners to act as the reference catalyst for the multi channel reactor experiments. 1ST PHASE: The reactor consisted of parallel reaction channels (10 cm long and square shaped) that were packed with Ru/Al2O3 (0.9 %wt Ru) catalyst particles. From experiments in three different sizes of channel: 2 mm x 2 mm, 3 mm x 3 mm, and 5 mm x 5 mm (at P = 8 bar, T = 388 K, with a liquid and gas flows L = 3.2 kg m-2 s-1, G = 1.35 x 10-2 kg m-2 s-1), it was shown that in a short 10 cm length of channel, a product yield up to ca. 29 % (with minimum 99.5 % selectivity) could be obtained. Conversions were highest in the 3 x 3 mm channel. From the experiments with the reactor mounted both in horizontal and vertical planes, it was shown that gravitational influences are minor. The choice of solvent was shown to affect the yield of benzaldehyde. The highest yield was with toluene; the application of dioxane/water mixture (70/30 by vol.) and N-methyl pyrrolidone (NMP) not only decreased the yield by factor 2, but NMP also caused deactivation of the catalyst. Hydrodynamic characteristics of the system were evaluated to establish pressure drop, effectiveness of gas/liquid mixing, and to confirm the nature of the gas-liquid flow regime. Operating the reactor at: 8 bar, 388 K, with a liquid flow L = 3.2 kg m-2 s-1 and gas flows G > 2.5 x 10-2 kg m-2 s-1; it was shown that even in a short 10 cm length of channel, a product yield of up to 55% (with 99.7% selectivity) could be obtained. Although the adiabatic temperature rise at 55% yield is estimated to be ca. 180 K, the reactor was shown to operate isothermally, due to the efficient removal of heat through the integrated micro heat exchange system. It was concluded that this structured design of a reactor showed considerable promise for the development of cleaner oxidation processes. Conversions up to 25% per 10 cm bed length were measured, giving TOF = 800 h-1, which is close to that reported in the literature for the same catalyst. By controlling the point of injection of oxygen into the reactor an increase in the yield of benzaldehyde formation was achieved. 2ND PHASE: Experiments were then performed using a Pt/C catalyst (3% Pt by weight) and pure dioxane or dioxane/water mixtures as solvents. In spite of the two-fold increase in the rate of oxidation (as the flowrate of oxygen was changed) a similar behaviour was observed. Faster kinetics, and therefore faster release of energy did not influence the temperature profile in the reactor (isothermal operation was maintained due to effective heat transfer). Despite higher rates of reaction the process soon became limited by chemical kinetics and not by mass transfer. Based on the results of these experiments a pilot scale reactor has been constructed consisting of 192 channels, with total length of catalytic bed equal 0.5 m. This has the capacity to produce 2 kg h-1 of product (aldehyde). Publications D.V. Bavykin, A.A. Lapkin, S.T. Kolaczkowski, P.K. Plucinski, Selective oxidation of alcohols in a continuous multifunctional reactor: ruthenium oxide catalysed oxidation of benzyl alcohol, Applied Catalysis, 288, 175-184 (2005). P.K. Plucinski, D.V. Bavykin, S.T. Kolaczkowski, A.A. Lapkin, Application of a structured multifunctional reactor for the oxidation of a liquid organic feedstock, Catalysis Today, 105 479 483 (2005). D.V. Bavykin, S.T. Kolaczkowski, A.A. Lapkin, P.K. Plucinski, Compact multichannel reactor for liquid phase oxidation of organic feedstocks, Proceedings of 7th World Congress of Chemical Engineering, IchemE, 2005. D.V. Bavykin, A.A. Lapkin, P.K. Plucinski, J.M. Friedrich, F.C. Walsh, TiO2 nanotube supported ruthenium (III) hydrated oxide: A highly active catalyst for selective oxidation of alcohols with oxygen, Journal of Catalysis, 235, 10-17 (2005). P.K. Plucinski, D.V. Bavykin, S.T. Kolaczkowski, A.A. Lapkin, Liquid phase oxidation of organic feedstock in a compact multichannel reactor, Ind. Eng. Chem. Res., 44, 9683-9690 (2005).

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