The light oil reserves are being depleted and the refining industry has to deal with more bituminous and shale reserves, and the present tendendy is an increasing demand of light products. The objective of this programme is to develop microporous heterogeneous catalysts, with pore sizes larger than currently available commercial cracking catalysts, for the conversion of heavy oil fractions. This should lead to a better utilization of available oil resources.
The new extra-large pore mesoporous MCM-41 materials were a great improvement compared with the restricted pore size of zeolite Y. Solid-state characterisations showed that the new materials are composed of hexagonal arrangements of one-dimensional pore systems with aluminosilicate walls and that they have a specific surface of up to 1000 m2/g. A pore size of 2.5 nm was obtained for MCM-41 by adsorption tests, between three and four times larger than the current zeolite catalysts. In the so-called H form, MCM-41 acts as a solid-state acid. Because of its high thermal stability it can be used as a catalyst component in acid catalysed cracking reactions even at temperatures above 500(C. Catalytic microactivity tests showed that the new materials could crack bulky and very branched molecules, whereas the conventional FCC catalysts were unable to do so.
The development of extremely stable, highly active and selective type materials applied as catalysts in modern refineries has become very important, especially the improved conversion of heavy oil fractions into useful light transportation fuels of high quality. Up to now the Si-rich ultra-stable zeolites with large and medium pore openings have received the most attention, limiting the conversion of heavier oil fractions due to the restricted pore dimensions of the commercial, zeolite-based catalysts. A promising alternative to overcome these limitations could probably be the application of extra large pore zeolite-like materials, such as mimics of VPI-5, MCM or cloverite, novel pillared materials and microporous titanosilicates. In order to activate these systems for acid catalysed conversion of heavy oil fractions the suggested materials must be modified.
The objectives are to synthesize and thoroughly characterize such materials, test for catalytic performance and stability, model reaction pathways and then try to improve the catalyst behaviour by catalyst modification.
The performance of the catalysts will be measured both in terms of producing the desired activity and selectivity and in terms of deactivation profiles. Regeneration procedures for deactivated catalysts will be investigated as well as the working catalyst make-up (i.e. particle size, use of binder, etc.).
The details of surface intermediates formed on these novel catalysts will be investigated using both spectroscopic techniques and theoretical modelling. In particular working catalysts will be monitored by state-of-the-art in situ solid-state NMR techniques which will give information about surface species formed at the active site within the interior of these extra large pore catalysts. The experimental evidence will then be used as a starting point for theoretical modelling of these surface intermediates and refinement of reaction pathways.
Finally, real working catalysts will be produced for pilot plant test studies.
Funding SchemeCSC - Cost-sharing contracts
20097 San Donato Milanese
L69 7ZD Liverpool
M60 1QD Manchester