MIL-100(Cr)
was synthesized and evacuated under different temperatures
to generate a series of heterogeneous catalysts for ethylene oligomerization.
These catalysts showed moderate catalytic activities for ethylene
oligomerization but high selectivities to low carbon olefins C6, C8,
and C10. Moreover, the oligomer distribution was different depending
on the evacuation temperature. The XPS results showed the reduction
of some CrIII active sites in the MIL-100(Cr) structure
to CrII active sites, which made the catalysts show polymerization
activities. The MIL-100(Cr)-250 catalyst evacuated at 250 °C
exhibited the highest oligomerization and polymerization activities
up to 9.27 × 105 g/(molCr·h) and 0.99 ×
105 g/(molCr·h) respectively. The oligomerization
selectivity to low carbon olefins C6, C8, and C10 was about 99%. The
byproduct polymer from MIL-100(Cr)-250 belonged to linear polyethylene
with ultrahigh molecular weight and broad molecular weight distributions.
This work demonstrated that MOFs containing coordinatively unsaturated
metal sites might be a promising selective catalyst for ethylene slurry
oligomerization.
Supporting information 1. CharacterizationPowder X-ray diffraction (PXRD) measurements were performed using a Rigaku D/MAX-2500 X-ray diffractometer with CuKa radiation. Samples were analyzed over a range of 2θ=1.5-10° using a step scan mode with a step rate of 1°/min. Scanning electron microscopy (SEM) measurements and X-ray electron spectroscopy (EDS)
Highly efficient, cis-selective, stable, recyclable and reusable heterogeneous single-site MOF-supported rhodium catalysts polymerize PA and its derivatives, producing cis-transoidal PPAs and their functional derivatives having a helical configuration or AIE properties.
The correct identification of active species is an important prerequisite to study the mechanism of coordinative polymerization of olefins, which can afford important theoretical guidance for the design and synthesis of new organometallic catalysts and high-performance polyolefin materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.