Mechanistic insight into initiation and chain transfer reaction of CO₂/cyclohexene oxide copolymerization catalyzed by zinccobalt double metal cyanide complex catalysts

Abstract

Although zinccobalt (III) double metal cyanide complex (ZnCo (III) DMCC) catalyst is a highly active and selective catalyst for carbon dioxide (CO2)/cyclohexene oxide (CHO) copolymerization, the structure of the resultant copolymer is poorly understood and the catalytic mechanism is still unclear. Combining the results of kinetic study and electrospray ionization‐mass spectrometry (ESI‐MS) spectra for CO2/CHO copolymerization catalyzed by ZnCo (III) DMCC catalyst, we disclosed that (1) the short ether units were mainly generated at the early stage of the copolymerization, and were hence in the “head” of the copolymer and (2) all resultant PCHCs presented two end hydroxyl (OH) groups. One end OH group came from the initiation of zinchydroxide (ZnOH) bond and the other end OH group was produced by the chain transfer reaction of propagating chain to H2O (or free copolymer). Adding t‐BuOH (CHO: t‐BuOH = 2:1, v/v) to the reaction system led to the production of fully alternating PCHCs and new active site of ZnOt‐Bu, which was proved by the observation of PCHCs with one end Ot‐Bu (and OCOOt‐Bu) group from ESI‐MS and 13C NMR spectra. Moreover, Zn−OH bond in ZnCo (III) DMCC catalyst was also characterized by the combined results from FT‐IR, TGA and elemental analysis. This work provided new evidences that CO2/CHO copolymerization was initiated by metalOH bond. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Power-to-Steel: Reducing CO2 through the Integration of Renewable Energy and Hydrogen into the German Steel Industry

“…Emissions arising from plant construction, fuel procurement and maintenance are not considered. For the calculation of the energy as well as process-related emissions, only CO 2 was included because the greenhouse gas emissions of the relevant energy carriers consist of 98.8% CO 2 and the process emissions of steel manufacturing of CO 2 only [24,25]. Secondly, selected measures and alternative processes that have the potential to reduce CO 2 emissions and incorporate renewable energy into the integrated steelworks are considered.…”

“…Under the condition that the export of electrical power and heat out of the balance area is constant, the lack of COG must be replaced by a substitute like natural gas. [25,35,46] and Section 4.1. All data relating to the production of a ton of pig iron.…”

“…The reference case of the conventional integrated steelworks, which is shown in Figure 7, was defined by the authors with the help of data from Sun 2012, UBA 2014 and Hensmann 2010 [25,35,46] and Section 4.1. The parts considered are the coke oven, sinter plant, blast furnace, a power plant for house requirements and export, as well as heat generation for export.…”

“…Figure 9 also shows energy demand in the year 2008 and CO2 emissions from the year 1990. These values were extrapolated with the help of data from 2012 and the corresponding years [21,25]. Total energy demand has decreased by 8% since 2008 and CO2 emissions by 30% since 1990.…”

CO2 Complexation and Activation by a Trost‐Bis(ProPhenol)Cobalt Complex

“…For this reason, its use as a raw material in industrial processes is being pursued with great interest, frequently inspiring the generation of new catalysts and stimulating research towards a greater understanding of the mechanisms involved in its chemical activation. [1][2][3][4][5][6] For example, cobalt-porphyrin, [7,8] cobalt-salen, [9][10][11] and cobaltbinol [12,13] complexes as well as zinc-cobalt double-metal cyanides [14,15] have been employed in copolymerization reactions involving carbon dioxide as substrate. Several other coupling reactions using CO 2 have recently been reported [16][17][18][19] based on cobalt catalysts.…”