Thursday Plenary Lecture: 2019 Award for Excellence in Natural Gas Conversion

We are pleased to welcome Dr. Unni Olsbye, Professor, University of Oslo, as the recepient of the 2019 Award for Excellence in Natural Gas Conversion and the speaker for the Thursday Plenary Lecture!

Natural Gas Conversion in Microporous Catalysts; Zeotypes and Metal Organic Frameworks

Since the first Natural Gas Conversion Symposium in Auckland, New Zealand, in 1987, the natural gas conversion area has evolved from a prospective field of intensive research efforts, to a mature field with major industrial implementation. In recent years, ethane-rich shale gas offered opportunities to successfully refurbish industrial naphta crackers into ethane crackers, which concomitantly intensified the search for alternative routes to propene and butene production.

This lecture will focus on two such routes that are currently under study in our group; the methanol to olefins (MTO) reaction, and the ethene oligomerization reaction. Both reactions are catalyzed by Brønsted acid sites in zeotype materials (including zeolites), and ethene oligomerization is further promoted by Ni sites ion-exchanged onto the lattice.

During the past decade, significant progress was made in the fundamental understanding of zeotype-catalyzed processes, owing to a combination of mechanistic studies, synthesis of materials with systematically modified properties (pore and cavity diameter, crystal size and morphology, acid-site strength, density and distribution) and improved operando and ex situ characterization techniques [1].

Considering the MTO reaction, the mechanism of alkene conversion to (poly-)aromatic compounds, and furthermore; the site selectivity of zeotype catalysts, is currently a hot topic. The first part of the lecture will be dedicated to recent advances in this research field [2]. 

The second part of the lecture will focus on the ethene oligomerization reaction. Industrial processes are currently carried out over homogeneous Ni-complex catalysts, and many studies addressed Ni-containing zeotypes as potential heterogeneous analogues [3]. An alternative approach, metal organic frameworks (MOFs), offers the possibility of anchoring Ni to an organic entity, similar to those found in commercial, homogeneous catalysts [4]. As one of a few examples where MOF catalysts are used to convert gas phase molecules, current insight in Ni-MOFs versus Ni-zeolites as ethene oligomerization catalysts will be presented.

A long-term goal of our research activity is to develop guiding principles for tailoring microporous catalysts towards selective applications. Experimental determination of intrinsic kinetic parameters is a prerequisite of this approach. However, it is a daunting task to obtain experimental data for individual reactions in zeotypes, due to the plethora of reactions that may take place simultaneously inside the porous network. For this reason, we are currently exploring the use of the Temporal Analysis of Products (TAP) technique to measure intrinsic kinetics of zeotype-catalyzed reactions [5]. This unique apparatus operates under vacuum conditions, and favors monomolecular interaction with surface sites. The status and prospects of such studies will be addressed in the final part of the lecture.

References

[1] Olsbye et al. Angew. Chemie Int. Ed., 2012, 51, 5810; Chem. Soc. Rev. 2015, 44, 7155; Ilias and Bhan, ACS Catalysis, 2013, 3, 18; Yarulina et al. Nature Catal. 2018, 1, 2398; Gounder and Iglesia, Acc. Chem. Res. 2012, 45, 229; Sarazen et al. J. Catal. 2016, 344, 553.

[2] Martinez-Espin et al.; J. Catal., 2017, 349, 136; Cat.Sci.Technol. 2017, 7, 2700; ACS Catalysis, 2017, 7, 5173; Yarulina et al, Nature Chemistry, 2018, 10, 809; Morten et al. ChemPhysChem. 2018, 19, 484.

[3] Hulea ACS Catalysis, 2018, 8, 3263; Brogaard and Olsbye ACS Catalysis 2016, 6, 1205.

[4] Canivet, JACS 2013, 135, 4195; Metzger JACS, 2017, 139, 757; Liu JACS, 2018, 140, 11174; Kømurcu et al (in preparation).

[5] Brogaard et al J. Catal., 2014, 314, 159; Redekop et al. (in preparation).

See the full list of plenary speakers here.