Parallel Catalyst Synthesis Protocol for Accelerating Heterogeneous Olefin Polymerization Research

Abstract

The data scientific approach has become an indispensable tool for capturing structure-performance relationships in complex systems, where the quantity and quality of data play a crucial role. In heterogeneous olefin polymerization research, the exhaustive and multi-step nature of Ziegler-Natta catalyst synthesis has long posed a bottleneck in synthetic throughput and data generation. In this contribution, a custom-designed 12-parallel reactor system and a catalyst synthesis protocol were developed to achieve the parallel synthesis of a magnesium ethoxide-based Ziegler-Natta catalyst. The established system, featuring a miniature reaction vessel with magnetically suspended stirring, allows for over a tenfold reduction in synthetic scale while ensuring the consistency and reliability of the synthesis. We demonstrate that the established protocol is highly efficient for the generation of a catalyst library with diverse compositions and physical features, holding promise as a foundation for the data-driven establishment of the structure-performance relationship in heterogeneous olefin polymerization catalysis.

Keywords: Ziegler-Natta catalyst; miniature; morphology; olefin polymerization; parallel synthesis.

Figure 1

Reactor setups for the synthesis of magnesium ethoxide as a catalyst solid precursor: (a) large-scale synthesis, and (b) small-scale parallel synthesis (adapted with permission from ref. [35] Copyright 2017 American Chemical Society). Inserted table lists the codes of MGE used for catalyst preparation. Note that all samples, except for MGE-STD-L, were synthesized using the parallel reactor setup in (b).

Figure 2

Catalyst synthesis setup and procedure: (a) typical procedure for catalyst synthesis; (b) conventional laboratory reactor setup; (c) 30 mL miniature reaction vessel equipped with a suspended magnetic stir bar; (d) SEM image of a catalyst synthesized using the miniature reaction vessel; and (e) SEM image of a catalyst synthesized using the same miniature reaction vessel but with an unsuspended magnetic bar (leading to morphological failure).

Figure 3

Parallel catalyst synthesis protocol: (a) illustration of the entire reactor system and the actual image of the module, and (b) optimized condition for the parallel synthesis of 12 catalysts using a 50 mL reaction vessel.

Figure 4

SEM images of catalysts prepared in parallel under identical conditions.

Figure 5

SEM images of catalyst samples prepared using different sources of MGE samples as a solid precursor. The * symbol indicates the reproduction test.

Figure 6

Pore size distribution of synthesized catalysts analyzed based on the NL-DFT method. V_p and W stand for pore volume and pore width, respectively.

Figure 7

Relationships between catalyst features: (a–c) chemical compositions, (d,e) physical features, and (f–h) interrelationships between chemical compositions and physical features. The correlation coefficients (r) are integrated into their respective plots.

Figure 8

Relationships (a) between the total internal donor content and propylene polymerization activity, and (b) between the OEt content and xylene-insoluble content of resultant polymer.