Future Development of Catalysis

7/27/2019 Future Development of Catalysis

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Future Development of Catalysis

Homogeneous catalysis

There is a need for correlation of structure, dynamicalrearrangements, transition states and reaction intermediates of

enzyme, heterogeneous and homogeneous catalytic systems through

investigations of the same reactions under similar experimental

conditions.

For example, correlations exist between metalloenzyme and heterogeneous transition metal catalytic

processes in the areas of alkane hydroxylation and dehydrogenation, olefin epoxidation, and nit rogen fixation,

despite the fact that heterogeneous catalysts typically operate under high temperature and sometimes high

pressure conditions, while enzymes catalyze similar transformations under ambient conditions.

Potentially acting between these extremes are synthetic metal complexes that mimic the metalloenzyme active

sites and catalyze reactions under relatively mild conditions.

New strategies of catalyst synthesis must be developed to establishmolecular control over the structure, location and promoter

distribution of catalysts. Molecular characterization of the working

catalysts can provide the crucial experimental information on

structural details and can lead to identification of elementary

reaction steps.

In the case of basic chemicals the chances for new catalyticprocesses are small, but they are better for higher value chemicals

such as fine and specialty chemicals. Pharmaceuticals and

agrochemicals are two areas where homogeneous catalysts have

advantages. Complex molecules can often be synthesized in single-

step onepot reactions with the aid of transition metals. This sector

has many potential points of overlap with biotechnology, especially

enzyme catalysis.


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Heterogeneous Catalysis

There is a demand in modern in-situ techniques for catalystinvestigation such as:

In-situ techniques for chemical analysis of catalyst surfaces with atomic resolution under actual operating

conditions; there is achieved time resolution that is shorter than turnover times

Techniques for rapid evaluation of both catalyst structure and adsorbate structure under reaction conditions;

the dynamic rearrangement of the catalytically active surface should be correlated with catalytic performance

in practice

Predictive techniques for guiding and accelerating the development of catalysts for specific applications.

Two main areas of future catalyst development can be expected: Improvement of existing processes: increasing the yield and selectivity, energy savings in the production

processes

Development of new processes: use of other raw materials with the aid of new catalysts.

Use of Other, Cheaper Raw Materials

Efforts are being made worldwide to produce valuable chemicalsfrom lower alkanes such as methane, ethane, propane, and butane

instead of the olefins that are currently used.

Natural gas, the main component of which is methane, is ofparticular interest as a raw material.

The activation of higher alkanes is also being intensivelyinvestigated. An example is the oxidative dehydrogenation of

ethane, propane, and isobutane to the corresponding alkenes and

oligomeric products.

A major challenge for catalyst research is the oxidative coupling ofmethanol to produce ethylene glycol.

Catalytic oxidations of hydrocarbons have relatively lowselectivities. Reactions with interesting perspectives are the direct

oxidation of propylene to propylene oxide, of benzene to phenol,

and of propane to isopropanol and acetone.


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Another challenge for the future is the exploitation of new rawmaterials and energy sources.

Other examples for a better utilization of alternative and renewable

feedstocks are:

Development of catalysts for depolymerizing mixed polymers Development of catalysts for the selective synthesis of chemicals

from CO and CO2

Development of catalysts for the conversion of cellulose andcarbohydrates to chemicals

Improve existing processes by reducing the levels of CO2 producedas a byproduct

Better strategies for catalysts development

There is great need for research on the behavior of catalyst surfacesthat consist of several components. The fundamental knowledgerequired, for example, to improve the selectivity of catalysts is also

lacking.

Studies of reaction intermediates and transition states that arecarried out at low pressures using model systems should be

correlated with studies of reaction intermediates during catalytic

reactions.

Interesting areas for investigations are the catalytic conversion ofchiral molecules and high temperature, short residence time

processes involving free radicals that include pyrolysis and catalytic

combustion.


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New strategies of catalyst synthesis must be developed to establishmolecular control over the structure, location and promoter

distribution of catalysts to achieve high selectivity.

A key current limitation in the discovery of new zeolites is the lackof fundamental understanding of the zeolite nucleation and

crystallization process. Therefore, correlations between structure-

directing templates and the resulting zeolite material have to be

achieved.

The principle technologies recommended for catalyst research and

development are:

New catalyst design:

Combined experimental mechanistic understanding, and improved

computational modeling of catalytic processes.

Computer aided, nanostructural fabrication of active sites producing

economically viable catalyst structures

High-throughput synthesis and testing of catalysts:

Identification of high-throughput methods for synthesizing catalysts

Development of high-throughput analytical techniques for evaluatingcatalyst performance

Development of reaction protocols for rapid screening of large numbers

of catalyst simultaneously at elevated pressure

The zeolites have major potential, and it is expected that especiallythe pentasils and the metal-doped zeolites will achieve wider

application in organic syntheses.

Another promising class of compounds are the heteropolyacids.Depending on the reaction conditions, they can act according tothree basic mechanisms: as normal surface catalysts, with

involvement of the entire volume, or as pseudo-liquid phase

catalysts.

Other catalysts for acid/base reactions will also increase inimportance.


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Future Development of Catalysis