Scheme1.Depolymerizationo fflexible PU foam by alcoholysis of carbamate and diarylurea groups with diethyleneg lycol. R'OH represents the polyether polyol.
The layered zeolite precursor RUB-36, consisting of ferrierite-type layers, can be transformed into a threedimensional framework through various methods such as topotactic condensation into the CDO topology, or interlayer expansion either in the presence or absence of a silylating agent. However, the plate-like morphology of the micrometer sized crystals hampers the accessibility of the 2D micropore system, in which the channels run parallel to the plates. With the aim of introducing mesoporosity, alkaline treatments were performed on different RUB-36 derived expanded materials, and on RUB-36 itself. The effect on the physicochemical properties was examined using N 2 physisorption, PXRD, SEM and 27 Al MAS NMR while the influence on the catalytic activity was evaluated using esterification and alkylation reactions. After calcination, the purely inorganic, interlayer expanded material could be transformed into a mesopore containing FER-type material by selective removal of the interlayer T-atom followed by the recombination of the layers. In the pre-calcination state, organic moieties -originating from the silylating agent or from the organic structure directing agent (OSDA) -increase the hydrophobicity of the interlayer expanded structure and its stability against the alkaline treatment. In RUB-36, the high OSDA content limited the amount of mesopore formation through alkaline treatment. However, using the appropriate conditions, the subsequent interlayer expansion of alkaline treated RUB-36 also resulted in a mesopore containing interlayer expanded structure.
The
direct incorporation of CO2 into value-added base
chemicals, such as methyl formate (MF), is a grand challenge to chemical
science. In this work, a base-free cascade catalysis system is described
to effectively convert carbon dioxide into MF. In the initial step
a well-established Ru complex (i.e., RuHCl(dppm)2, dppm
= 1,1-bis(diphenylphosphino)methane) is able to hydrogenate CO2 into formic acid, which subsequently undergoes a heterogeneous
acid catalyzed esterification with methanol to selectively produce
MF. Here, the small pore MOF UiO-66, a Zr-terephthalate, is identified
as a promising heterogeneous acid and its Zr6 cluster is
modified to understand the effect of Brønsted/Lewis acidity on
the performance. Moreover, this heterogeneous acid catalyst could
be reused for multiple times without significantly losing its activity.
The Cover Feature shows the depolymerization of a flexible polyurethane foam in diglycerol as a novel, promising alcoholyzing agent. This results in a split‐phase system with the upper phase containing the apolar polyether polyol and the lower phase the excess diglycerol and aromatic products. The recycled polyether polyol is rendered suitable for the production of new flexible polyurethane foam by a single washing step with diglycerol. A first step towards the valorization of the lower phase was also taken by hydrolysis of the newly formed carbamates to toluenediamines. More information can be found in the Full Paper by T. Vanbergen et al.
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