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Professor John Dennis

Professor John Dennis

Professor in Chemical Reaction Engineering

University of Cambridge,
Department of Chemical Engineering and Biotechnology,
Pembroke Street

Cambridge CB2 3RA
Office Phone: 01223 334787

Biography:

Degrees

1981                M.Eng. (Hons), First Class Chemical Engineering Tripos, University of Cambridge

1985                Ph.D Department of Chemical Engineering, University of Cambridge.

1993                M.B.A., Distinction, City University.

Posts Held

1984-1989       University Lecturer, Department of Chemical Engineering, University of Cambridge.

1986                C.Eng., Member of the Institution of Chemical Engineers (MIChemE).

1989-1999       Consultant Chemical Engineer (Partner: Davidson Dennis Consulting).

1996-1999       Visiting Professor, University College London.

1999-2002       Research Facilitator, Dept. of Chemical Engineering, University of Cambridge.

2002-2004       University Lecturer, Dept. of Chemical Engineering, University of Cambridge.

2004-               Fellow, Selwyn College, Cambridge.

2004-               Fellow of the Institution of Chemical Engineers (FIChemE).

2004-2008       University Senior Lecturer, Dept. of Chemical Engineering, U. of Cambridge.

2004-               College Lecturer, DoS in Chem. Engineering and IB Engineering, Selwyn College.

2008-               Reader in Chemical Reaction Engineering, U. Cambridge

 

Research Experience

Dr. Dennis was a Lecturer in the Department of Chemical Engineering from 1984 to 1989 having previously been an undergraduate and PhD student there. During this period he published on the control of sulphur emissions from fluidised bed combustors and on the problems of gas combustion in fluidised beds. He left Cambridge to become an engineering consultant in 1989 specialising in the solution of difficult process or economic problems, with areas of technical interest including heat and mass transfer in reactors, combustion, and fluidised bed reactions. He has had close involvement with collaborative research involving academia and industry. He is a member of the EPSRC's Peer Review College. He returned to the University and was a University Lecturer from October, 2002, Senior Lecturer from October, 2004 and has been Reader in Chemical Reaction Engineering since October, 2008. Recent areas of research include the fluidised bed gasification of biomass, fundamental studies of fluidised bed hydrodynamics using MRI, discrete element modelling of fluidised beds, clean coal technology using hydrogasification followed by combined reforming and shift with in situ CO2 removal, novel fluidising techniques for processing fuels with a high content of volatile matter, chemical looping combustion, scale-down of the Fischer Tropsch reaction, the production of transport fuels from algae and LCA studies of biofuels. He has published 100 papers on combustion, combustion-related topics and the physics of fluidisation.

Research themes

Bioenergy:
  • Gasification of lignocellulosic biomass
  • Generation of pure hydrogen from biomass gasification
  • Conversion of biomass to transport fuels via gasification and Fischer Tropsch conversion
  • Upstream and down stream processing of algae for transport fuels
Hydrocarbon Recovery:
  • Chemical looping combustion of solid fuels
  • Use of Ca-based sorbents for the separation of CO2 from flue gases
  • Enhancement of the water-gas shift reaction in the presence of Ca-based sorbents
Carbon Capture, Storage & Use:
  • Chemical looping combustion of solid fuels
  • Use of Ca-based sorbents for the separation of CO2 from flue gases
  • Enhancement of the water-gas shift reaction in the presence of Ca-based sorbents
Sustainable Chemical Conversions:
  • Chemical looping approaches for CO2 removal
  • LCA studies of biofuel systems
  • Scale-down of Fischer-Tropsch
  • New sorbents for CO2 removal
Resource Dynamics:

Resource constraints arising from future scenarios for biofuel use

Research Interests

There is urgency to design (a) radically-new processes utilising solid fossil-fuels for electricity, whilst capturing CO2 efficiently, and (b) sustainable processes for liquid biofuels. My Research Group emphasises fundamental principles, in three themes:

1)  Innovative combustion and gasification of fossil and renewable fuels, with separation of pure CO2 without energy penalty.

2)  Physics of granular flows. Processes in (1) depend on efficient gas-solid reactions and solids flow. We use innovative combinations of new (e.g. Magnetic Resonance Imaging, MRI) and existing (e.g. Particle Image Velocimetry) techniques, underpinned by theoretical approaches (e.g. Discrete Element Modelling, DEM).

3)  Sustainable transport biofuels embraces system-level studies of sustainability, innovative processing of algae and new approaches to Fischer-Tropsch (FT).

1. Innovative combustion and gasification. In basic chemical-looping (CL), gaseous fuel is combusted and the normally-expensive separation of CO2 from nitrogen in air is achieved without penalty38 using a solid oxide “oxygen-carrier”. CL with solid fuels is difficult because fuel and carrier cannot be separated during carrier regeneration: we have published,38,39 and demonstrated,83,85,86,90 a suitable technique and have developed carriers durable for many cycles of operation.64,73,87,94,95 Some are sufficiently reactive to oxidise hydrocarbons at low temperatures. We have extended CL using iron oxides to produce clean hydrogen from biomass, uncontaminated with COx and suitable for fuel cells. Being far less scale-dependent than natural-gas reforming, it is ideal for local hydrogen production71 and the structured-oxides are durable, even when reduced to iron-metal.82,83,87,93

Gasifying coal to CO and H2 allows efficient CO2 capture by the shift equilibrium, (i) CO(g)+H2O(g)=CO2(g)+H2(g), in contact with solid CaO, (ii) CaO(s)+ CO2(g)=CaCO3(s), which removes CO2, moving (i) to maximise H2. Heating CaCO3 releases the CO2 for sequestration. The capacity of CaO from natural minerals falls markedly with number of forward/reverse steps in (ii).36,54 We have created synthetic sorbents63 which, uniquely, increase in CO2-capacity as CO2 concentration increases, and do not decay in capacity.67,76In situ reaction/X-ray diffraction and STEM are being used to give fundamental insights into better sorbents (with Profs. Redfern and Midgley). Other work81 has shown that CaO catalyses reaction (i), a discovery complicating design for reactions (i) and (ii).

2. Physics of granular flows. With Prof. Gladden, we have applied ultra-rapid MRI to observe fluidised beds internally.33,35,40,43,47,48-50,55-59 Studies included: dispersion of solids in real-time,33,55 rise velocities of bubbles and slugs40, splitting and coalescence of bubbles40, time-averaged bulk motion of particles,35 jetting at distributors,35,48,78,98 voidage and granular temperature in real-time.47,58,88 These studies have settled some long-standing controversies, e.g. the rise velocity of a bubble in a continuously-bubbling bed equals that of a single bubble rising alone.40 It is clear when gas issues from the distributor as a stream of bubbles or a jet.48,78,98 For scale-up, we are conducting a comparison of MRI with ECT (with Prof. Fan, Ohio) on fast fluidisation. A major target is to image gas in fluidised beds with MR.40 Laser investigations (acetone-PLIF) have given interesting insights into fluidised-bed freeboard mixing.66,77 We have been able to validate DEM with MR.59,80 Planned research will compare MR with X-ray tomography (UCL) and PEPT ( Birmingham).

3. Sustainable transport biofuels. Life-cycle analyses of biofuels have established important benchmarks,70,84,92,97e.g. algal growth using closed reactors is unlikely ever to be carbon-neutral.92 Other work is examining resource constraints in the future use of biofuels, as part of a University consortium. We are part of the Algal Bioenergy Consortium (http://www.plantsci.cam.ac.uk/Smith/abc.html), working on the upstream and downstream processing of algae for liquid biofuels and other products..89,96 With FT, the objective is scale-down to produce fuels from local biomass: multi-scale approaches will be central, e.g., by a unique capability to compare results with a similar reactor constructed for MR-imaging of reactions.

Keywords

  • Chemistry

Key Publications

 

1.       DENNIS, J. S., HAYHURST, A.N. & MACKLEY, I.G. (1983). The combustion of propane in a fluidised bed. Proc. Comb. Inst., 29, 1205-1212.

2.       DENNIS, J. S. & HAYHURST, A. N. (1984). The effect of pressure on the kinetics and extent of sulphation of calcareous materials. Instn. Chem. Engnrs. Symp. Ser. No. 87, 61-68.

3.       DENNIS, J. S. & HAYHURST, A. N. (1984). The effect of temperature on the kinetics and extent of SO2 uptake by calcareous materials during the fluidised bed combustion of coal. Proc. Comb. Inst., 20, 1347-1354.

4.       DENNIS, J. S. & HAYHURST, A. N. (1986). A simplified analytical model for the rate of reaction of SO2 with limestone particles. Chem. Engng. Sci., 41, 25-36.

5.       DENNIS, J. S. & FIELDES, R. B. (1986). Simplified model for the rate of sulphation of limestone particles. Chem. Engng. Res. Des., 64, 279-287.

6.       DENNIS, J. S. & HAYHURST, A. N. (1987). The effect of CO2 on the kinetics and extent of calcination of limestone and dolomite particles in fluidised beds. Chem. Engng. Sci., 42, 2361-2372.

7.       DENNIS, J. S. & HAYHURST, A. N. (1987). The calcination of limestone particles in fluidised beds. Proceedings of FLUIDISATION V, Lyngby, Denmark, 563-570.

8.       DENNIS, J. S. & HAYHURST, A. N. (1988). The formation of SO3 in a fluidised bed. Comb. & Flame, 72, 241-258.

9.       DENNIS, J. S. & HAYHURST, A. N. (1988). A model for the continuous desulphurisation of a fluidised bed combustor using limestones, dolomites or related solid sorbents. J. Inst. Energy, 61, 98-109.

10.   DENNIS, J. S. & HAYHURST, A. N. (1989). Alternative sorbents for flue-gas desulphurisation, especially in fluidised bed combustors. J. Inst. Energy, 62, 202-207.

11.   DENNIS, J. S., FAWKNER, R.D. & KLUTH, P.P. (1990). Bubble formation at orifices in pulsed, flowing liquids. Trans. IChemE. Part A., 68, 71-73.

12.   DENNIS, J. S. & HAYHURST, A. N.(1990). Mechanism of the sulphation of calcined limestone particles in combustion gases. Chem. Engng. Sci., 45, 1175-1187.

13.   DENNIS, J. S. & HYDE, A. R. (1989). Gas hold-up and bubble sizes in a filamentous fermentation broth. Advances in Biochemical Engineering, The Institution of Chemical Engineers, pp. 29-43.

14.   HARRISON, S. T., CHASE, H. A. & DENNIS, J. S. (1990). The effect of culture history on the disruption of Alcaligenes eutrophus by high pressure homogenisation. Separations for Biotechnology 2, proceedings of the 2nd International Symposium on Separations for Biotechnology, University of Reading, 10th - 13th September, 1990.

15.   DENNIS, J. S. (1990). Bioprocessing equipment. Engineering, 230, 38-39.

16.   HARRISON, S. T., DENNIS, J. S. & CHASE, H.A. (1991). Combined chemical and mechanical processes for the disruption of bacteria. Bioseparation, 2, 95-105.

17.   HARRISON, S. T., CHASE, H. A. & DENNIS, J. S. (1991). The lysis of gram-negative Alcaligenes eutrophus by enzymes from Cytophaga. Biotechnology Techniques, 5, 115-120.

18.   DENNIS, J.S. (1994). Developments in the isolation of proteins - introduction. J. Chemical Technology and Biotechnology., 59, 105-105.

19.   RAM, K., VICKROY, T.B., LAMB, K.A., SLATER, N.K.H., DENNIS, J.S. & DUFFY, L.E. (2000). Mixing in process vessels used in biopharmaceutical manufacturing. Biotechnology Progress, 16, 244-247.

20.   DENNIS, J.S. & HAYHURST, A.N. (2002). Fundamental studies of the kinetics and extent of the reaction of SOx with calcium-based sorbents in fluidised bed reactors. Keynote paper presented at the CREST International Symposium on Advanced DESOx Process, 6-7th December, The University of Tokyo, Tokyo.

21.   WHITE, C., DENNIS, J.S. & GADD, G.M. (2003). A mathematical process model for cadmium precipitation by sulphate-reducing bacterial biofilms. Biodegradation, 14, 139-151.

22.   HARRIS, A.T., SCOTT, S.A., DENNIS, J.S., HAYHURST, A.N. & DAVIDSON, J.F. (2003). The gasification of sewage sludge in bubbling fluidised beds. Proceedings of FBC17; 17th International Conference on Fluidized Bed Combustion, Jacksonville, Florida, 2003, ASME, Paper No. 70.

23.   SCOTT, S.A., HARRIS, A.T., DENNIS, J.S., HAYHURST, A.N. & DAVIDSON, J.F. (2003). Gasification of biomass: the consequences of equilibrium. Proceedings of FBC17; 17th International Conference on Fluidized Bed Combustion, Jacksonville, Florida, 2003 ASME, Paper No. 72.

24.   SCOTT, S.A., DAVIDSON, J.F., DENNIS, J.S., FENNELL, P.S. & HAYHURST, A.N. (2005). The rate of gasification by CO2 chars from waste.  Proc. Comb. Inst., 30, 2151-2159.

25.   SCOTT, S.A., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2004). Heat transfer to a single sphere immersed in beds of particles supplied by gas at rates above and below minimum fluidisation. Ind. Eng. Chem. Res., 43, 5632-5644.

26.   HARRIS, A.T., SCOTT, S.A., DENNIS, J.S., HAYHURST, A.N. & DAVIDSON, J.F. (2004). Combustion of sewage sludge in bubbling fluidised beds. Proceedings of Fluidization XI, Ischia, Italy, May, 2004, Engineering Conferences Internation, Brooklyn, NY11201. Paper EE1.

27.   REES, A.C., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2005). A comparison between the rise velocities of inert spheres in slugging and bubbling beds, fluidised by air at ambient conditions. Chem. Eng. Sci., 60, 1143-1153.

28.   DENNIS, J.S., LAMBERT, R.J., MILNE, A.J., SCOTT, S.A. & HAYHURST, A.N. (2005). The kinetics of combustion of chars derived from sewage sludge. Fuel, 84, 117-126.

29.   REES, A.C., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2005). The rise and combustion of particles of sewage sludge and petroleum coke in a slugging fluidized bed. Proceedings of 18th International Conference on Fluidized Bed Combustion, 373-384.

30.   FENNELL, P.S., HAYHURST, A.N., DENNIS, J.S., KADCHHA, S., & LEE, H-Y (2005). The kinetics of oxidation of chars from three different coals, as measured in fluidized beds. Proceedings of 18th International Conference on Fluidized Bed Combustion, 881-894.

31.   SCOTT, S.A., DENNIS, J.S., DAVIDSON, J.F. & HAYHURST, A.N. (2006). Thermogravimetric measurements of the kinetics of pyrolysis of dried sewage sludge. Fuel, 85, 1248-1253.

32.   SCOTT, S.A., DENNIS, J.S., DAVIDSON, J.F. & HAYHURST, A.N. (2006). An algorithm for determining the kinetics of devolatilisation of complex solid fuels from thermogravimetric experiments. Chem. Eng. Sci., 61, 2339-2348.

33.   FENNELL, P.S., DAVIDSON, J.F., DENNIS, J.S., GLADDEN, L.F., HAYHURST, A.N., MANTLE, M.D., MÜLLER, C.R., REES, A.C., SCOTT, S.A. & SEDERMAN A.J. (2005). A study of the mixing of solids in gas-fluidized beds, using ultra-fast MRI. Chem. Eng. Sci., 60, 2085-2088.

34.   FENNELL, P.S., DENNIS, J.S. & HAYHURST, A.N. (2006). The production of nanoparticles of MgO, BaO and A12O3 in a premixed flame and its relation to a flame’s structure. 5th International Seminar on Flame Structure, The Siberian Academy of Sciences, Novosibirsk, July, 2005. Combustion, Explosion, and Shock Waves, 42, 642-648.

35.   REES, A.C., DAVIDSON, J.F. DENNIS, J.S., FENNELL, P.S GLADDEN, L.F. HAYHURST, A.N. MANTLE, M.D.  MÜLLER, C.R.  & SEDERMAN A.J. (2006). The nature of the flow just above the distributor of a gas-fluidized bed, using Magnetic Resonance Imaging. Chem. Eng. Sci., 61, 6002–6015.

36.   FENNELL, P. S., PACCIANI, R., DAVIDSON, J. F., DENNIS, J.S. & HAYHURST, A. N. (2006). The Use of Limestone Particles for the Capture of CO2: Its Initial Reactivity and Loss of Reactivity after Repeated Cycles of Calcination and Carbonation. Proceedings of FBC19, May 21 – 24, 2006. Paper No. 59. ISBN 3-200-00645-5.

37.   SCOTT S.A., DAVIDSON J.F., DENNIS J.S. & HAYHURST A.N. (2007). The devolatilisation of a large particle of a complex fuel (sewage sludge) in a fluidised bed. Chem. Eng. Sci., 62, 584-598.

38.   DENNIS, J.S., SCOTT, S.A. & HAYHURST, A.N. (2006). In situ gasification of coal using steam with chemical looping: a technique for isolating CO2 from burning a solid fuel. J. Energy Institute, 79, 187-190.

39.   DENNIS, J.S., SCOTT, S.A. & HAYHURST, A.N. (2006). In situ gasification of a solid fuel and CO2 using chemical looping. A.I.ChE.J., 52, 3325-3328.

40.   MÜLLER, C. R., DAVIDSON, J. F., DENNIS, J. S., FENNELL, P.S., GLADDEN, L. F., HAYHURST, A. N., MANTLE, M. D., REES, A.C. & SEDERMAN, A.J. (2006). Real time measurement of bubbling phenomena in a 3-D gas-fluidized bed using ultra fast Magnetic Resonance Imaging. Physical Review Letters, 96, 15404-1 to 15404-4.

41.   FENNELL, P.S., DENNIS, J.S. & HAYHURST, A.N. (2006). The size distributions of nanoparticles of the oxides of Mg, Ba and Al in flames: their measurement and dependence on the concentrations of free radicals in the flame. Proc. Comb. Inst., 31 (2007), 1939-1945.

42.   DENNIS, J.S., SCOTT, S.A. & HAYHURST, A.N. (2006). The combustion of large particles of char in bubbling fluidised beds: the dependence of Sherwood number and the rate of burning on particle diameter. Comb. & Flame, 147, 185-194.

43.   MÜLLER, C.R., DAVIDSON, J.F., DENNIS, J.S., FENNELL, P.S., GLADDEN, L.F., HAYHURST, A.N., MANTLE, M.D., REES, A.C. & SEDERMAN, A.J. (2007). Rise velocity of bubbles and slugs in gas-fluidised beds: ultra-fast Magnetic Resonance Imaging. Chem. Eng. Sci., 62, 82-93.

44.   FENNELL, P.S., KADCHHA, S., LEE, H-Y, DENNIS, J.S. & HAYHURST, A.N. (2007). The measurement of the rate of burning of different coal chars in an electrically heated fluidised bed of sand. Chem. Eng. Sci., 62, 608-618.

45.   REES, A.C., DAVIDSON, J.F., DENNIS, J.S., & HAYHURST, A.N., (2005). The combustion and gasification of sewage sludge and waste materials in a slugging gas-fluidized bed. Proceedings of the 7th World Congress of Chemical Engineering, Glasgow, UK, 84633.

46.   REES, A.C., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2006). The rise of buoyant fuel particles in a slugging gas-fluidised combustor. Chem. Eng. Res. Des., 84 (A4), 319-327.

47.   MÜLLER, C.R., DAVIDSON, J.F., DENNIS, J.S., FENNELL, P.S., GLADDEN,  L.F., HAYHURST, A.N.  MANTLE, M.D., REES, A.C., & SEDERMAN, A.J. (2006). The rise of bubbles and slugs in gas-fluidized beds using Ultra-fast Magnetic Resonance Imaging. Fifth World Congress on Particle Technology 2006, Orlando, FL, USA. Paper 242a., 10 pp.

48.   MÜLLER, C.R., REES, A.C., MANTLE, M.D., SEDERMAN, A.J., DAVIDSON, J.F., DENNIS, J.S., FENNELL, P.S., GLADDEN,  L.F., & HAYHURST, A.N. (2006). Investigation of the formation of jets in a three-dimensional gas-fluidized bed using Magnetic Resonance Imaging. Fifth World Congress on Particle Technology 2006, Orlando, FL, USA. Paper 236a, 11 pp.

49.   MÜLLER, C. R., DAVIDSON, J. F., DENNIS & HAYHURST, A. N. (2007). A study of the motion and eruption of a bubble at the surface of a two-dimensional fluidised bed using particle image velocimetry (PIV). Ind. Eng. Chem. Res., 46, 1642-1652.

50.   MÜLLER, C.R., HOLLAND, D.J., DAVIDSON, J.F., DENNIS, J.S., GLADDEN, L.F., HAYHURST, A.N.  MANTLE, M.D., REES, A.C., & SEDERMAN, A.J. (2007). Rapid two-dimensional imaging of bubbles and slugs in a three-dimensional, gas-solid, two-phase flow system using ultrafast magnetic resonance. Physical Review E, 75 (2), Art No 020302 Part 1.

51.   FENNELL, P.S., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A. N. (2007). Regeneration of sintered limestone sorbents for the sequestration of CO2 from combustion and other systems. J. Energy Institute, 80, 116-119.

52.   DAVIES, N.H., DENNIS, J.S. & HAYHURST, A. N. (2007). Reaction between calcium oxide and hydrogen sulphide and also its modelling for a fluidised bed coal gasifier. J. Energy Institute, 80, 65-72.

53.   HARDING, K.G., DENNIS, J.S., VON BLOTTNITZ, H. & HARRISON, S.T.L. (2007). Environmental analysis of plastic production processes: Comparing petroleum-based polypropylene and polyethylene with biologically-based poly-beta-hydroxybutyric acid using life cycle analysis. J. Biotechnology, 130, 57-66.

54.   FENNELL, P. S., PACCIANI, R., DAVIDSON, J. F., DENNIS, J.S. & HAYHURST, A. N. (2007). The effects of repeated cycles of calcination and carbonation on a variety of different limestones, as measured in a hot fluidized bed of sand. Energy & Fuels, 21, 2072-2081.

55.   HOLLAND, D.J., MÜLLER, C.R., DAVIDSON, J.F., DENNIS, J.S., GLADDEN, L.F., HAYHURST, A.N.  MANTLE, M.D., & SEDERMAN, A.J. (2007). Time-of-flight variant to image mixing of granular media in a 3D fluidized bed. J. Magnetic Resonance, 187, 199-204.

56.   MÜLLER, C.R., DAVIDSON, J.F., DENNIS, J.S., FENNELL, P.S., GLADDEN, L.F., HAYHURST, A.N.  MANTLE, M.D., REES, A.C., & SEDERMAN, A.J. (2007). Oscillations in gas-fluidized beds: Ultra-fast magnetic resonance imaging and pressure sensor measurements. Powder Technology, 177, 87-98.

57.   HOLLAND, D.J., FENNELL, P.S., MÜLLER, C.R., DENNIS, J.S., GLADDEN, L.F. & SEDERMAN, A.J. (2007). In situ measurement of dynamic mixing in gas-solid fluidized beds using magnetic resonance. Paper presented at Fluidization XII, Harrison Springs, Canada, 13-17 May, 2007.

58.   HOLLAND, D.J., MÜLLER, C.R., DENNIS, J.S., GLADDEN, L.F. & SEDERMAN, A.J. (2008). Spatially resolved measurement of anisotropic granular temperature in gas-fluidised beds. Powder Technology, 182, 171-181.

59.   MÜLLER, C.R., HOLLAND, D.J., SCOTT, S.A., DAVIDSON, J.F., DENNIS, J.S., HAYHURST, A.N., GLADDEN, L.F. & SEDERMAN, A.J. (2007). Experimental validation of a discrete element model code by means of magnetic resonance using a fluidized bed as a test case. Paper presented at 6th International Conference on Multi-Phase Flow (ICMF 2007), Leipzig, 9th-13th July.

60.   REES, A.C., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2007). The apparent viscosity of the particulate phase of bubbling gas-fluidised beds: a comparison of the falling or rising sphere technique with other methods. Trans. I. Chem. E. A, 85, 1341-1347.

61.   FENNELL, P.S., DENNIS, J.S. & HAYHURST, A.N. (2007). The sampling of nanoparticles of MgO formed when doping an oxygen-rich flame with magnesium. The measurement of the concentrations and size distributions of these nanoparticles. Comb. Flame, 151, 560-572.

62.   MÜLLER, C.R., HOLLAND, D.J., SEDERMAN, A.J. SCOTT, S.A., DENNIS, J.S. & GLADDEN, L.F. (2008). Granular temperature: Comparison of magnetic resonance measurements with discrete element model simulations, Powder Technology 184, 241-253.

63.   PACCIANI, R., MÜLLER, C.R. DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2008). Synthetic Ca-based solid sorbents suitable for capturing CO2 in a fluidized bed, Canadian Journal of Chemical Engineering, 86, 356-366, 2008.

64.   CHUANG, S.Y., DENNIS, J.S., HAYHURST, A.N. & SCOTT, S.A. (2008). Development and performance of Cu-based oxygen carriers for chemical-looping combustion. Comb. Flame, 154, 109-121.

65.   HARDING, K.G., DENNIS, J.S., VON BLOTTNITZ, H. & HARRISON, S.T.L. (2008). A life cycle comparison between inorganic and biological catalysts for the production of biodiesel. J. Cleaner Production, 16, 1368-1378.

66.   HARTUNG, G., MÜLLER, C.R., HULT, J., KAMINSKI, C.F. & DENNIS, J.S. (2008). Laser diagnostic investigation of the bubble eruption patterns in the free board of fluidized beds. Part 1: Optimized Acetone PLIF measurements, Industrial & Engineering Chemistry Research, 47, 5686-5697.

67.   PACCIANI, R., MÜLLER, C.R., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2008). How does the concentration of CO2 affect its uptake by a synthetic Ca-based solid sorbent?, AIChE Journal, 54, 3308-3311.

68.   BOHN, C.D., MÜLLER, C.R., CLEETON, J.P.E., DENNIS, J.S. & SCOTT, S.A. (2008). Production of very pure hydrogen with simultaneous capture of carbon dioxide using the redox reactions of iron oxides in packed beds, Industrial & Engineering Chemistry Research 47, 7623-7630.

69.   IVES, M. MUNDY, R.C., FENNELL, P., DAVIDSON, J.F., HAYHURST, A.N., DENNIS, J.S. & SCOTT, S.A. (2008). Comparison of different natural sorbents for removing CO2 from combustion gases, as studied in a bench-scale fluidized bed. Energy & Fuels, 22, 3852-3857.

70.   STEPHENSON, A.L., DENNIS, J.S. & SCOTT, S.A. (2008). Improving the sustainability of the production of biodiesel from oilseed rape in the UK. Process Safety and Environmental Protection, 86, 427-440.

71.   CLEETON, J.P.E., BOHN, C.D. MÜLLER, C.R., DENNIS, J.S. & SCOTT, S.A. (2009). Clean hydrogen production and electricity from coal via chemical-looping: identifying a suitable operating regime, International Journal of Hydrogen Energy, 34, 1-12.

72.   HOLLAND, D.J., MARASHDEH, Q., MÜLLER, C.R., WANG, F., DENNIS, J.S., FAN, L.-S. & GLADDEN, L.F. (2009). Comparison of ECVT and MR measurements of voidage in a gas-fluidized bed, Industrial & Engineering Chemistry Research, 48, 172-181.

73.   CHUANG, S.Y., DENNIS, J.S., HAYHURST, A.N. & SCOTT, S.A. (2009). Kinetics of the chemical looping oxidation of CO by a co-precipitated mixture of CuO and Al2O3. Proc. Combustion Institute, 32, 2633-2640.

74.   FENNELL, P.S., DENNIS, J.S. & HAYHURST, A.N. (2009). The order with respect to oxygen and the activation energy for the burning of anthracitic char in oxygen in a fluidised bed, as measured using a rapid analyser for CO and CO2. Proc. Combustion Institute, 32, 2051-2058.

75.   TIGHE, C.J., DENNIS, J.S., HAYHURST, A.N. & TWIGG, M.V. (2009). The reactions of NO with diesel soot, fullerene, carbon nanotubes and activated carbons doped with transition metals. Proc. Combustion Institute, 32, 1989-1996.

76.   DENNIS, J.S. & PACCIANI, R. (2009). The rate and extent of uptake of CO2 by a synthetic, Ca-containing sorbent. Chem. Eng. Sci., 64, 2147-2157.

77.   MÜLLER, C.R., HARTUNG, G., DAVIDSON, J.F., HULT, J., KAMINSKI, C.F. & DENNIS, J.S. (2009). Laser diagnostic investigation of the bubble eruption patterns in the free board of fluidized beds. Part 2: Simultaneous acetone PLIF and stereoscopic PIV measurements, AIChE Journal, 55, 1369-1382.

78.   MÜLLER, C.R., HOLLAND, D.J., DAVIDSON, J.F., DENNIS, J.S., GLADDEN, L.F., HAYHURST, A.N., MANTLE, M.D. & SEDERMAN, A.J. (2009). Geometrical and hydrodynamical study of gas jets in packed and fluidized beds using Magnetic Resonance. Canadian Journal of Chemical Engineering, 87, 517-525.

79.   PACCIANI, R., MÜLLER, C.R., DAVIDSON, J.F., DENNIS, J.S. & HAYHURST, A.N. (2009). Performance of a novel synthetic Ca-based sorbent suitable for desulphurising flue gases in a fluidised bed. Industrial & Engineering Chemistry Research, 48, 7016-7024.

80.   MÜLLER, C.R., SCOTT, S.A., HOLLAND, D.J., CLARKE, B.C., SEDERMAN, A.J., DENNIS, J.S. & GLADDEN, L.F. (2009) Validation of a discrete element model using magnetic resonance measurement. Particuology, 7, 297-306.

81.   MÜLLER, C.R., PACCIANI, R., SCOTT, S.A., BOHN, C.D. & DENNIS, J.S. (2009). Investigation of the enhanced water-gas shift reaction using natural and synthetic sorbents for the capture of CO2. Industrial & Engineering Chemistry Research 48, 10284-10291.

82.   BOHN, C.D., CLEETON, J.P.E., MÜLLER, C.R., DAVIDSON, J.F., HAYHURST, A.N., SCOTT, S.A. & DENNIS, J.S. (2009). The kinetics of the reduction of iron oxide by carbon monoxide mixed with carbon dioxide. AIChE Journal, 56, 1016-1029.

83.   DENNIS, J.S. (2009). Chemical looping combustion: one answer to sequestering carbon dioxide. Invited lecture, ECM 2009: Fourth European Combustion Meeting, Vienna, April, 2009 (Paper: http://www.combustion.org.uk/ECM_2009/P999505.pdf).

84.   STEPHENSON, A.L., VON BLOTTNITZ, H., BRENT, A.C., DENNIS, J.S. & SCOTT, S.A. (2010). Global warming potential and fossil-energy requirements of biodiesel production scenarios in South Africa. Energy & Fuels, 24, 2489-2499.

85.   DENNIS, J.S. & SCOTT, S.A. (2010). In situ gasification of a lignite coal and CO2 separation using chemical looping with a Cu-based oxygen carrier. Fuel, 89, 1623-1640.

86.   DENNIS, J.S., MÜLLER, C.R., & SCOTT, S.A. (2010). In situ gasification and CO2 separation using chemical looping with a Cu-based oxygen carrier: performance with bituminous coals. Fuel, 89, 2353-2364.

87.   KIERZKOWSKA, A.M., BOHN, C.D., SCOTT, S.A., CLEETON, J.P., DENNIS, J.S. & MÜLLER, C.R., (2010). Development of oxygen carriers for chemical looping using sol-gel. Industrial & Engineering Chemistry Research 49, 5383-5391.

88.   HOLLAND, D.J., MÜLLER, C.R., DENNIS, J.S., GLADDEN, L.F. & DAVIDSON, J.F. (2010). Magnetic resonance studies of fluidisation regimes. Industrial & Engineering Chemistry Research 49, 5891-5899.

89.   SCOTT, S.A., DAVEY, M.P., DENNIS, J.S., HORST, I., HOWE, C.J., LEA-SMITH, D,J. & SMITH, A. (2010). Biodiesel from algae: challenges and prospects. Current Opinion in Biotechnology, 21, 277-286.

90.   BROWN, T.A., DENNIS, J.S., SCOTT, S.A., DAVIDSON, J.F. & HAYHURST, A.N. (2010). Gasification and chemical looping combustion of lignite char in a fluidised bed of iron oxide. Energy & Fuels, 24, 3034-3048.

91.   SULTAN, D.S., MÜLLER, C.R. & DENNIS, J.S. (2010). Capture of CO2 using sorbents of calcium magnesium acetate (CMA). Energy & Fuels, 24, 3687-3697.

92.   STEPHENSON, A.L., KAZAMIA, E., DENNIS, J.S., HOWE, C.J., SCOTT, S.A. & SMITH, A. (2010). Life cycle assessment of potential algal biodiesel production in the United Kingdom: a comparison of raceways and air-lift tubular reactors. Energy & Fuels, 24, 4062-4077.

93.   BOHN, C.D., CLEETON, J.P.E., MÜLLER, C.R., CHUANG, S.Y., SCOTT, S.A. & DENNIS, J.S. (2010). Stabilising iron oxide used in cycles of reduction and oxidation for hydrogen production. Energy & Fuels, 24, 4025-4033.

94.   CHUANG, S.Y., DENNIS, J.S., HAYHURST, A.N. & SCOTT, S.A. (2010). Kinetics of the oxidation of a co-precipitated mixture of Cu and Al2O3 by O2 for chemical looping combustion. Energy & Fuels, 24, 3917-3927.

95.   CHUANG, S.Y., DENNIS, J.S., HAYHURST, A.N. & SCOTT, S.A. (2010). Kinetics of the chemical looping oxidation of H2 by a co-precipitated mixture of CuO and Al2O3. Chemical Engineering Research & Design, doi: 10.1016/j.cherd.2010.08.003.

96.   STEPHENSON, A.L., DENNIS, J.S., HOWE, C.J., SCOTT, S.A. & SMITH, A. (2010). Influence of the nitrogen-limitation regime on the production by Chlorella vulgaris of lipid for biodiesel feedstocks. Biofuels, 1, 47-58.

97.   STEPHENSON, A.L., DUPREE, P., SCOTT, S.A. & DENNIS, J.S. (2010). The environmental and economic sustainability of potential bioethanol from willow in the UK. Bioresource Technology, 101, 9612-9623.

98.   PORE, M., HOLLAND, D.J., CHANDRASEKERA, T.C., MUELLER, C.R., SEDERMAN, A.J., DENNIS, J.S., GLADDEN, L.F. & DAVIDSON, J.F. (2010). Magnetic resonance studies of a gas-solids fluidized bed: jet-jet and jet-wall interactions. Particuology, doi: 10.1016/j.partic.2010.07.015.