A large number of ehemieal reaetions of importance to the petrochemieal, bulchemical, fine ehemical and pharmaeeutieal industry are based upon eatalrocesses. Over 90% of all chomical conversions involves the use of a suicatalyst in one or more of the production steps. The most common processes involve the reaction between liquid and gaseous reactants in the presence of a sutable, most often a solid. catalyst. Well known reaction classes include hydgenations, hydrations and oxidations. Many of these processes are camed outtehwise in a slurry reactor with a solid catalyst, which is highly dispersed as very small particles in order to enhance the available surface area and to reduce transport limitations as much as possible The need for small catalyst particles then poses problems to the efficient operation of the process. In order to guarantee product quality, to ensure recovery of (expensive) catalyst ial and to reduce environmental effects. the catalyst needs to be removeery low levels by filtration, which is a time consuming, expensive and cumbersome process. In fact, the need to remove the catalyst from the reaetion prot sets a lower size on the size of the catalyst powder practically usable (ut 10-20 Fm). Even so the relatively long residence time in batch processes ean lead to low selectivities with additional eosts and environmental probleising from the subsequent purification steps. The batch slurry processes are also lirnited to relatively small throughput reactions. For the much larger throughput hydroprocessing reactions used in the petroleum industry continuous ration can only be achieved with trickle bed reactors using much larger (1-2m) catalyst particles. Even so the relatively small size of the particles andhe hydrodynamics of the beds usually limits the reactors to co-current operation, which can be disadvantageous, hilst the size of the particles still impose severe mass transfer constraints that limits the use of these reactors toatively slow reactions. The triekle bed reactors are also limited to oxide supports as the required physical form and macrostructure cannot be achievecurrently available carbons even though they frequently give better cataperformance. Thus, the existing three-phase processes presently in use have major disadvantages. In this project we will investigate the potential of a novel synthetic carbon catalyst system to overcome these problems. The carbonin principle be produced in a wide range of physical forrns from small (particles.to large monolithic structures. The key targethis project will be to build into these macroforms a wide variety of macro a meso pore structures which will then allow us to establish the precise impa of macro, meso and micro structure on mass and heat transfer in gas-liquid-solid catalytic reactions and to tailor the structure precisely for the reenvironment required. The flexibility of the carbon systems also allows the srface chemistry in terms of acidity/basicity and hydrophobic/hvdrophilic character to be manipulated. It is anticipated that the ability to control the wettabilit of the surface could be particular critical in aqueous phase air oxon reactions. to bring about changes in surface wetting which can play a crucial role in reactions involving aqueous solutions. These optimised pore and surface structures can then be extended into a range of monolithic structure the channel architecture can be further adjusted to maximise the hvdrc properties. The project will therefore comprise an integrated approach to support development and reactor engineering bringing together three of the fst exponents in liquid phase catalysis reaction engineering and monolithie rctor studies along with a major catalyst producer and and end-user. These support studies will be integrated with detailed studies into aqueous phase dation reactions, and in particular the conversion of cyclohexanol to adipiecid, where the activity and selectivity are expeeted to show a significantendence on the support characteristies, and the hydrogenation of maleic anhydride to butane diol and THF which is know to be sensitive to the oxidation state of the carbon surface. The expected outcomes of the project will be:- 1. Aetailed understanding of the role of miero/meso and macro pore structure on the performance of liquid phase catalytic processes 2. carbon supports wmised pore structures, surface chemistry and physical forms for a range of liquid phase processes (slurry, trickle bed and monolithic) 3. monolithicatalyst supports with optimised channel geometries 4. A detailed undersg of the factors controlling aqueous phase air oxidation reactions and optimised catalysts and supports for the cyclohexanol to adipic acid process 5. Aonstration of the benefits of the new support systems in trickle bed hydrogenation processes.
Funding SchemeCSC - Cost-sharing contracts
3454 PK De Meern
GU3 2AF Guilford Surrey
KT16 3HR Addlestone Surrey
2628 BL Delft