Bulk chemicals such as ethylene glycol (EG) can be industrially synthesized from either ethylene or syngas, but the latter undergoes a bottleneck reaction and requires high hydrogen pressures. We show that fullerene (exemplified by C
60
) can act as an electron buffer for a copper-silica catalyst (Cu/SiO
2
). Hydrogenation of dimethyl oxalate over a C
60
-Cu/SiO
2
catalyst at ambient pressure and temperatures of 180° to 190°C had an EG yield of up to 98 ± 1%. In a kilogram-scale reaction, no deactivation of the catalyst was seen after 1000 hours. This mild route for the final step toward EG can be combined with the already-industrialized ambient reaction from syngas to the intermediate of dimethyl oxalate.
Carboncones, a special family of all-carbon allotropes, are predicted to have unique properties that distinguish them from fullerenes, carbon nanotubes, and graphenes. Owing to the absence of methods to synthesize atomically well-defined carboncones, however, experimental insight into the nature of pure carboncones has been inaccessible. Herein, we describe a facile synthesis of an atomically well-defined carboncone[1,2] (C70H20) and its soluble penta-mesityl derivative. Identified by x-ray crystallography, the carbon skeleton is a carboncone with the largest possible apex angle. Much of the structural strain is overcome in the final step of converting the bowl-shaped precursor into the rigid carboncone under mild reaction conditions. This work provides a research opportunity for investigations of atomically precise single-layered carboncones having even higher cone walls and/or smaller apex angles.
Knowledge on the initial and intermediate pyrolysis products
of
biomass is essential for the mechanistic investigation of biomass
pyrolysis and further optimization of upgrading processes. The conventional
method can only detect the final products, which do not resemble the
initial or intermediate pyrolysis products. Here, we introduce a direct
orifice sampling combined with atmospheric pressure photoionization
mass spectrometry (APPI-MS) for in situ online analysis of the evolved
volatile initial products from the pyrolysis of biomass. Pyrolysis
experiments of both dimeric model compound (guaiacylglycerol-β-guaiacyl
ether, GGGE) and poplar wood were carried out to validate the generality
of the method. Generally, secondary reactions can be reduced by shortening
the distance between the sample and sampling orifice. Large molecular-weight
initial products up to trimers were detected during the pyrolysis
of poplar wood, and no initial products larger than trimers were detected.
It is inferred that in situ APPI immediately after sample extraction
ensures efficient and effective product detection. Furthermore, the
present work offers a promising feasible method for online tracing
of reaction intermediates not only in pyrolysis but also in various
reactive processes (e.g., catalytic reaction, oxidation) under operando
conditions.
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