Advantages of an Emulsion‐Produced Ziegler‐Natta Catalyst Over a Conventional Ziegler‐Natta Catalyst

Abstract

Summary: Self‐supported and MgCl2‐supported Ziegler‐Natta catalysts, produced by two catalyst synthesis methods are compared. Borealis Polymers OY (Finland), who supplied the catalysts, developed the catalyst synthesis methods. The first method (Method One) is based on an emulsion system and consists of an in situ single step preparation. The second method (Method Two) consists mainly of two steps: formation of the catalyst carrier particles, and their subsequent impregnation with the active material. The results showed that Method One produced catalysts of compact, spherical particles with good intra‐particle homogeneity and a narrow particle size distribution. On the other hand, Method Two produced catalyst particles whose properties depended directly on that of the catalyst carrier: they were spherical but very porous, with a broad particle size distribution. Polymer particles produced with the two catalyst systems are perfect replicas of the catalyst particles. Fines formed either during catalyst preparation or during polymerization were observed only with the catalyst prepared using Method Two. The particles of the catalysts produced using Methods One and Two had similar activities, independent of the initial particle size. Fragmentation of catalyst particles was very fast for both catalyst systems and was only observed to be 100% completed using the catalyst produced with Method One. Studies of the thermal properties showed that the catalyst prepared using Method One produced poly(propylene) of higher crystallinity and with a narrower melting peak.SEM images of polymer particles produced by (A) Method One and (B) Method Two.magnified imageSEM images of polymer particles produced by (A) Method One and (B) Method Two.

Evaluation of the Initial Stages of Gas‐Phase Ethylene Polymerizations with a SiO2‐Supported Ziegler–Natta Catalyst

“…Microscopy has been used by several research groups for in situ monitoring of homopolymerizations and copolymerizations reactions in the gas phase, mainly because of the non-destructive feature of this technique. [33] Recently, Abboud et al [34][35][36] employed videomicroscopy to follow the polymer particles melting obtained from heterogeneous catalysts. Laser scanning confocal fluorescence microscopy is also available for online monitoring of olefin polymerization.…”

Uma revisão sobre polimerização de olefinas usando catalisadores Ziegler-Natta heterogêneos

“…novo método para observação em linha das partículas poliméricas em crescimento, baseado na combinação de imagens de infravermelho e microscopia ótica, com a finalidade de acompanhar in situ a evolução da temperatura da superfície da partícula. Dada a sua natureza não destrutiva, técnicas de acompanhamento in situ baseadas em imagens tomadas com auxílio de um microscópio ótico são hoje empregadas por diversos grupos de pesquisa para acompanhamento de reações de homopolimerização e copolimerização em fase gasosa [84][85][86][87] . Recentemente, Xalter [88] e Xalter and Mülhaupt [89] empregaram uma técnica de espalhamento de luz (Focused Beam Reflectance Measurement -FBRM) acoplada à microscopia ótica para o monitoramento em linha do crescimento de partículas de polietileno, permitindo a determinação da distribuição do tamanho de partículas em polimerizações em lama conduzidas com catalisadores heterogêneos suportados em sílica e cloreto de magnésio.…”

Polymerization on Molecular Catalysts

“…A detailed insight also in particle growth and fragmentation processes is available by a new innovative tool: video microscopy [198,215,216,218,[221][222][223][224][225][226]. This technique, first applied by Reichert and coworkers [227], permits the simultaneous detection of the individual behavior of a large number of catalyst particles in gas-phase polymerization.…”