Computational Modelling of Structure
and Catalytic Properties
of Silica-Supported Group VI Transition
Metal Oxide Species
Jarosław Handzlik
Abstract Chromium, molybdenum and tungsten oxides supported on amorphous
silica are catalysts for many reactions, including large-scale industrial processes.
Although these systems have been extensively studied for many years, there are still
a few unresolved issues, concerning mainly the nature of the active sites and mechanisms of their formation. Computational studies, using cluster or periodic models to
represent the catalyst surface, are helpful in interpretation of spectroscopic data and
can provide complementary information about the catalytic process. In this chapter,
such computational works on CrO x /SiO 2 , MoO x /SiO 2 and WO x /SiO 2 systems are
presented. It is seen that coordination environment of the transition metal, determined also by local surface properties, is a key factor influencing catalytic activity
of the surface metal species. This results in complex structure–activity relationships.
While a great progress has been achieved in modelling of these systems, from simple
clusters to advanced periodic slabs, theoretical determination of complex reaction
mechanisms using surface models with representative distribution of metal sites is
still a challenge for computational catalysis.
1 Introduction
Group VI transition metal oxides supported on amorphous silica are effective catalysts for many important reactions, including large-scale industrial processes like
ethene polymerization or alkene metathesis. These ill-defined systems have been
extensively studied for many years using both experimental and theoretical methods. Nevertheless, the structure of the surface chromium, molybdenum and tungsten
oxide species on silica has been a subject under debate for a long time, and sometimes
contradictory conclusions, based on spectroscopic data, were drawn. Moreover, the
nature of the active sites, usually surface organometallic species, as well as the way
J. Handzlik (B)
Faculty of Chemical Engineering and Technology, Cracow University of Technology,
ul. Warszawska 24, 31-155 Kraków, Poland
e-mail: jhandz@pk.edu.pl
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_11
315
and Catalytic Properties
of Silica-Supported Group VI Transition
Metal Oxide Species
Jarosław Handzlik
Abstract Chromium, molybdenum and tungsten oxides supported on amorphous
silica are catalysts for many reactions, including large-scale industrial processes.
Although these systems have been extensively studied for many years, there are still
a few unresolved issues, concerning mainly the nature of the active sites and mechanisms of their formation. Computational studies, using cluster or periodic models to
represent the catalyst surface, are helpful in interpretation of spectroscopic data and
can provide complementary information about the catalytic process. In this chapter,
such computational works on CrO x /SiO 2 , MoO x /SiO 2 and WO x /SiO 2 systems are
presented. It is seen that coordination environment of the transition metal, determined also by local surface properties, is a key factor influencing catalytic activity
of the surface metal species. This results in complex structure–activity relationships.
While a great progress has been achieved in modelling of these systems, from simple
clusters to advanced periodic slabs, theoretical determination of complex reaction
mechanisms using surface models with representative distribution of metal sites is
still a challenge for computational catalysis.
1 Introduction
Group VI transition metal oxides supported on amorphous silica are effective catalysts for many important reactions, including large-scale industrial processes like
ethene polymerization or alkene metathesis. These ill-defined systems have been
extensively studied for many years using both experimental and theoretical methods. Nevertheless, the structure of the surface chromium, molybdenum and tungsten
oxide species on silica has been a subject under debate for a long time, and sometimes
contradictory conclusions, based on spectroscopic data, were drawn. Moreover, the
nature of the active sites, usually surface organometallic species, as well as the way
J. Handzlik (B)
Faculty of Chemical Engineering and Technology, Cracow University of Technology,
ul. Warszawska 24, 31-155 Kraków, Poland
e-mail: jhandz@pk.edu.pl
© Springer Nature Switzerland AG 2019
E. Broclawik et al. (eds.), Transition Metals in Coordination Environments,
Challenges and Advances in Computational Chemistry and Physics 29,
https://doi.org/10.1007/978-3-030-11714-6_11
315