11th International Congress On Catalysis - 40th Anniversary, Proceedings of the 11th ICC

964 Pages·1996·27.74 MB·English

by  Joe W. Hightower

xix
PREFACE
It seems highly appropriate that the Eleventh International Congress on Catalysis be held in
Baltimore, USA, less than 200 km from the birthplace of these quadrennial events that began
in Philadelphia in 1956. Planning for this 40th Anniversary Meeting has been coordinated by
Gary L. Hailer, with the support of the Organizing Committee comprised of John N. Armor,
Alexis T. Bell, W. Curtis Conner, Jr., Dady B. Dadyburjor, W. Nicholas Delgass, Sergio
Fuentes, Richard D. Gonzalez, W. Keith Hall, Joe W. Hightower, Enrique Iglesia, Leo E.
Manzer, James Maselli, Daniel E. Resasco, Kathleen C. Taylor, M. Albert Vannice, and
Bohdan Wojciechowski.
The PROCEEDINGS contain 541 papers - 7 plenary lectures and 831 submitted papers
selected for oral presentation. The plenary lectures include five overviews of vital research
areas by highly respected researchers and two overviews of advances in the science and
technology of catalysis made during the last 40 years. The first group explores the forces that
drive innovation in catalysis, constrained geometry in metallocene olefin polymerization,
characterization and design of oxide surfaces, photocatalysis, and factors required in the
molecular design of catalysts. Two others are presented by researchers who attended the first
ICC meeting 40 years ago and who have been substantive contributors to science and
engineering developments that have occurred since then.
The 831 submitted papers were selected in the following manner. From a total of 125
submitted two-page abstracts, 651 were identified by peer review and evaluation of the
Program Committee to be expanded into 10-page (maximum) camera-ready manuscripts.
Submitted manuscripts were then peer-reviewed by at least two experts in the field according
to standards comparable to those used for archival journals. Diversity in country origin was
also considered, and an attempt was made to minimize multiple publications for individual
research groups. Consequently, the 831 papers included herein should be considered as
peer-reviewed publications that represent the worldwide state-of-the-art in catalysis research.
These PROCEEDINGS of the International Congress on Catalysis differ from those published
previously in two important ways. First, the papers were published PRIOR to the meeting for
distribution to all delegates who attended the meeting in Baltimore. Second, none of the
discussion at the meeting is included. With publication costs skyrocketing, we have elected
to abandon the tradition of including the discussion, realizing that in so doing a valuable part
of the meeting will be lost forever to posterity. However, it does have the advantage of
smaller size (only two volumes, < 1,600 pages) which should make the books more attractive
to libraries and other repositories of research literature.
XX
Finally, I would like to thank my co-editor, Nick Delgass, and Gary Heller for assistance in
processing the paper revisions and to specially acknowledge Alex Bell and Enrique Iglesia,
chair and co-chair of the Program Committee, for their excellent and timely management of
the difficult but crucial task of paper selection. I am also grateful to Drs. Huub Manten of
Elsevier Science for the fantastic cooperation the company provided in getting these two
volumes printed. Most important, I wish to thank all the authors of the 541 papers appearing
in these PROCEEDINGS for their diligence in faithfully meeting the exceedingly short
deadlines that were necessary to get the material into print prior to the meeting.
Joe W. Hightower, Editor Houston, TX (USA)
J.W. Hightower, W.N. Delgass, E. Iglesia and A.T. Bell (Eds.)
11th International Congress on Catalysis - 40th Anniversary
Studies in Surface Science and Catalysis, Vol. 101
(cid:14)9 1996 Elsevier Science B.V. All rights reserved.
DRIVING FORCES FOR INNOVATION IN APPLIED CATALYSIS
lan .E Maxwell
Koninklijke/ShelI-Laboratorium, Amsterdam (Shell Research B.V.),
P.O. Box 38000, 1030 ,NB Amsterdam, Netherlands
1. INTRODUCTION
Recent governmental sponsored studies ni both the SU and Europe have
recognized the vital role of catalytic technologies for sustainable economic growth
ni the future. For example, it has been estimated that in developed countries
catalysis contributes directly and indirectly through processes and products to some
20-30% of GDP (Gross National Product). Furthermore, catalytic environmental
technologies such sa automobile exhaust catalysts and the selective catalytic
reduction (SCR) DeNOx systems ni power plants have already significantly
contributed to the reduction of environmentally harmful emissions into the lower
atmosphere.
nI addition, these studies have identified catalysis sa not only being pervasive
but also offering significant scope for further innovative development of new and
improved technologies for environmentally acceptable processes and products ni the
future. The spectrum of process industries which are directly impacted by catalysis
include for example, oil refining, natural gas conversion, petrochemicals, fine
chemicals and pharmaceuticals. Environmental catalytic technologies also play an
important role in emission control systems for power generation, fossil fuel driven
transportation, oil refining and chemical industries.
Catalytic technologies typically embrace a wide range of disciplines such as
heterogeneous and homogeneous catalysis, materials science, process technology,
reactor engineering, separation technology, surface science, computational
chemistry and analytical chemistry (Figure 1). Innovation ni this field si therefore
very often achieved by lateral thinking across these different disciplines. This
presentation will attempt to develop this theme further by means of examples from
recent commercial successes and from this platform provide some guidelines for
multi-disciplinary approaches at the academic and industrial interface to further
enhanced innovation ni catalytic technologies ni the future.
2. OIL REFINING AND NATURAL GAS CONVERSION
The discipline of materials science, for example, has a major impact on
innovation ni catalysis. Developments ni the field of porous solids have led to some
tal
Figure 1. Disciplines of Prime Importance to Catalytic Technologies
new catalytic processes in the refining area based on novel shape selective micro-
porous materials. Two such new processes which have recently been commer-
cialized based on these types of materials include the selective isomerization of n-
butene to iso-butene 1 (MTBE precursor) and iso-dewaxing of lubeoils 2.
Interestingly, both groups of industrial researchers (Shell and Chevron groups,
respectively) involved in these developments combined the disciplines of
computational chemistry, materials science andheterogeneous catalysis to gain an
in-depth understanding of the relationships between the detailed topology of the
micro-porous materials and the shape selective catalytic performance.
In the case of n-butene isomerization it was demonstrated (Figure 2) that the
ideal micro-pore topology led to retardation of the C8 dimer intermediate and that
the catalyst based on the ferrierite structure was close to optimal in this respect 1 .
For selective isodewaxing a one-dimensional pore structure which constrained the
skeletal isomerization transition state and thereby minimized multiple branching
such as the SAPO-1 1 structure was found to meet these criteria. Clearly, these are
ideal systems in which to apply computational chemistry where the reactant and
product molecules are relatively simple and the micro-porous structures are ordered
and known in detail.
Another recent new application of a microporous materials in oil refining is the
use of zeolite beta as a solid acid system for paraffin alkylation 3. This zeolite
based catalyst, which is operated in a slurry phase reactor, also contains small
amounts of Pt or Pd to facilitate catalyst regeneration. Although promising, this
novel solid acid catalyst system, has not as yet been applied commercially.
08
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noitisoP PMT sv tsellams etiloez ring mortsgnA
Figure 2. Comparison of Calculated Diffusional barriers for 2,4,4-trimethyl-3-
pentane (TMP) in Various Zeolites and Molecular Sieves
A non-acidic isomerization catalyst system has unexpectedly emerged from
recent studies by French workers 4 ni the area of Mo-oxycarbides. Although at an
early stage of development, these new materials exhibit high selectivities for the
isomerization of paraffins such as n-heptane. An alternative non-carbenium ion
mechanistic route to achieve isomerization of higher alkanes could potentially
overcome some of the limitations of conventional solid acid based catalyst
systems.
Novel combinations of heterogeneous catalysis, reactor technology and
separation technologies have also led to major innovations. Examples include
catalytic distillation which si now widely applied for the manufacture of MTBE with
other potential applications under development 5. Another example of multi-
disciplinary synergy in this context which was recently commercialised is the so-
called Synsat process 6 developed jointly by the Criterion and Lummus companies
for enhanced deep hydrogenation and desulphurization of diesel fuels. This process
employs a multiple catalyst bed system in a single reactor shell with intermediate
by-product gas removal and optional counter-current gas/liquid flow in the bottom
catalyst bed (Figure 3). Government legislation related to aromatics and sulphur
contents of diesel fuels has become more stringent and global ni recent years such
that the development of improved catalytic hydrotreating processes is most timely.
Catalytic membranes, which combine the disciplines of heterogeneous catalysis,
separation technology, materials science and reactor engineering, which have for
some time held considerable promise now appear to be gradually emerging as viable
technologies. Promising potential applications include propane to aromatics 7 and
catalytic oxidation of methane to synthesis gas using air as the oxidant 8. nI the
former example, Japanese workers 7 applied a Pd-alloy membrane reactor (PMR)
hserF feed ...... i=
rotcaeR
pu-ekaM 2H ~ tsylataC A p/1
ct
2Hpp
delcyceR ~ tsylataC B
ropaV ot
diuqil/ropav
diuqil ~ ~ tsylataC C /noitarapes
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Figure 3. The Synsat Process for Deep Hydrotreating of Diesel Fuels
58
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o
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> 56
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02 04 I ................. 06 I 08 I 1 0O
noisrevnoC fo enaporP %
Cat. Ga-H-ZSM5
K377
Figure 4. Comparison of Propane Aromatization Performances of a Palladium
Membrane Reactor (PMR) and a Conventional Reactor (CR) using a Ga-H-ZSM-5
Catalyst
to shift the equilibrium for the dehydroaromatization of propane. This RMP system
resulted in a significant improvement ni the selectivity towards the desired mixed
aromatic products (Figure 4).
For the partial oxidation of methane a catalytic membrane system under
development by researchers at the Argonne National laboratory 8 effectively
separates oxygen from air which si then passed through the membrane ni an
anionic form to react with methane in the presence of catalyst. High conversion and
selectivity levels to synthesis gas have been claimed, although space velocities
have not yet been published. Such new catalytic processes can potentially reduce
the costs of synthesis gas production and therefore positively impact the overall
economics of natural gas conversion technology.
New developments in the field of ceramic foam monoliths could also potentially
provide new catalytic process technology for the conversion of methane into
synthesis gas. For example, workers at Minnesota University 9 have achieved high
synthesis gas yields at both high temperatures and space velocities using rhodium
supported on a ceramic foam.
3. CHEMICALS
New materials are also finding application ni the area of catalysis related to the
Chemicals industry. For example, microporous 10 materials which have titanium
incorporated into the framework structure (e.g. so-called TS-1) show selective
oxidation behaviour with aqueous hydrogen peroxide as oxidizing agent (Figure 5).
Two processes based on these new catalytic materials have now been developed
and commercialized by ENI. These include the selective oxidation of phenol to
catechol and hydroquinone and the ammoxidation of cyclohexanone to e-
caprolactam.
It was soon recognized that the TS-1 system has limitations particularly due to
the small pore system which imposed restrictions on the molecular size of the
HO HO HrA HOrA
,
HO
R ,R H
HOrA R ,~:::0 +
'R HO
R HON,~
Figure 5. Range of Selective Oxidation Reactions Catalyze by the TS-1 Zeolite
System Using Aqueous H202 sa Oxidizing Agent
reactant molecules. More recently therefore titanium has been incorporated into
larger pore zeolites 11 (e.g. beta and ZSM-48) and even mesoporous structures
such as MCM-41 12. These larger pore materials also enable more bulky
molecules such organic hydroperoxides to be used as oxidising agents. This field
is still growing rapidly and would appear to hold promise for the development of
new and improved heterogeneous catalyst systems for selective oxidation reactions
of value to the chemicals industry.
Base catalysis si another area which has received a recent stimulus from
developments ni materials science and microporous solids ni particular. The Merk
company, for example, has developed a basic catalyst by supporting clusters of
cesium oxide in a zeolite matrix 13 . This catalyst system has been developed to
manufacture 4-methylthiazole from acetone and methylamine.
Heteropolyacids are also beginning to emerge from academic laboratories and
find commercial applications. Showa Denko, for example, claim to have a process
14 for the direct oxidation of ethylene to acetic acid employing a bifunctional
Pt/heteropolyacid catalyst system.
The potential synergies between the disciplines of homogeneous and
heterogeneous catalysis have also long been recognized but progress in the past
has generally been frustrated by intangible technical problems. Particularly
challenging is the goal of immobilizing homogeneous catalyst systems onto solid
supports without incurring catalyst loss by leaching under reaction conditions. A
particularly elegant approach to this problem involves the immobilization of a metal
complex in a thin film of polar solvent (e.g. water) which is adsorbed on a high
surface area hydrophilic support (e.g. silica). Such a system has been successfully
applied in the laboratory 15 to immobilize a homogeneous water soluble chiral
hydrogenation catalyst based on ruthenium (Figure 6). Using this catalyst a high
degree of enantioselectivity was achieved for na important hydrogenation step in
the synthesis of (S)-naproxen na( anti-inflammatory drug).
4. EMISSION CONTROL
Monolithic structures, often based on ceramic materials, are increasingly being
applied in catalysis. The initial major thrust of monoliths was in the area of
automobile exhaust catalyst systems where they are now applied exclusively. The
demand for improved performance of these emission control systems, particularly
under high temperature conditions is driving new developments such as ceramic
foam technologies. Catalytic combustion, particularly for application in gas turbines,
si another emerging field of technology where the developments in monolithic
structures will be of growing importance. The Osaka Gas and Kobe Steel companies
16 have jointly developed a catalytic monolith which operates up to 1300 ~ and
has been tested ni a 160 kW gas turbine. New ceramic materials based on Mn-
substituted hexa-aluminates provide the high temperature stability required of
catalytic monoliths for these demanding applications.
2rA IC
P~ / IC
P/Ru.~
2rA
" (cid:127) (cid:127)
,)aN3OS(PANIB-uR J
= m - NaO~SC,~' -
-
2H ~
H2OC
OeM OeM
)S( - nexorpan
Figure 6. Immobilization of Chiral Ruthenium Hydrogenation Catalyst in a Thin
Hydrophilic Film on a Porous Glass Support
Examples of multi-disciplinary innovation can also be found in the field of
environmental catalysis such as a newly developed catalyst system for exhaust
emission control in lean burn automobiles. Japanese workers 1 7 have successfully
merged the disciplines of catalysis, adsorption and process control to develop a so-
called NOx-Storage-Reduction (NSR) lean burn emission control system. This NSR
catalyst employs barium oxide as an adsorbent which stores NOx as a nitrate under
lean burn conditions. The adsorbent is regenerated in a very short fuel rich cycle
during which the released NOx is reduced to nitrogen over a conventional three-way
catalyst. A process control system ensures for the correct cycle times and
minimizes the effect on motor performance.
5. FUTURE CHALLENGES
The above examples should serve to reinforce the multi-disciplinarity of catalytic
technologies. However, to further exploit the significant potential of catalysis for
innovation and renewal across a broad range of industries multi-discplinary
approaches to problem solving will be vital to success. This ingredient for success
is, in general, recognized within industrial research laboratories where multi-
disciplinary project teams are commonly deployed. However, this approach is
traditionally less common in academic laboratories which generally tend to be more
narrowly focussed in terms of disciplinary skills.
Another element of concern at this interface is the perceived gap between
academic basic research and industrial applied research. The recent trend towards
shorter term goals within industrial research laboratories has further exacerbated
( ) .~
oo
Sectors
Enabling
Multi-sector
Technologies
Emerging
Multi-sector
Technologies
Figure 7. Programme Model for Proposed UK National Institute of Applied Catalysis
this situation whereby discontinuities are perceived to exist between basic and
applied catalysis. Both these factors, which are likely retarding innovation and the
potential synergies between industrial and academic laboratories in the field of
catalysis, have been termed the "innovation gap". nI Europe, particularly in the UK
and the Netherlands, this mismatch has been recognized and some government
supported initiatives are currently in progress.
In the Netherlands, for example, a type of "virtual" organization called NIOK has
been established to foster multi-disciplinary inter-university linkages and to
strengthen the relationships with industry. More recently the UK has also launched
a similar initiative with the intention of forming an organization based on both
"virtual" and "hard core" components involving both academia and industry. This
proposed new UK organization is termed NIAK (National Institute of Applied
Catalysis). This NIAK organizational model is directly aimed at closing what is
perceived to be a substantial "innovation gap" between industry and academia in
the UK. A programme model has been recently developed for NIAC (Figure 7) which
contains three separate components defined as emerging, enabling and sectors. The
emerging and enabling components are envisaged to contain elements of common
interest to all the industrial members whereas the sectorial programmes will be
much more specifically oriented towards the individual needs of each industrial
sector.
Thus, in order to fully realize the potential of catalytic technologies not only will
this require technical innovation in multi-disciplinary teams but also the appropriate
organizational structures which maximize the synergies between academic and
industrial research. The countries which recognize this potential and provide the