2 research outputs found
Sustainable Hydrogen Production via Sorption Enhanced Reforming of Complex Biorefinery Side Streams in a Fixed Bed Adiabatic Reactor
In this work, sorption
enhanced steam reforming is explored as
a potential solution for the valorization of gaseous streams recovered
from biorefinery hydrogenation processes. The hydrogen content of
such streams limits the hydrocarbon conversion in conventional steam
reforming due to thermodynamic and kinetic constraints. A previously
developed 1D dynamic heterogeneous model of an adiabatic reactor was
thus applied to evaluate the effect of H2 dilution on the
performance indicators of the sorption enhanced reforming process.
The mathematical model analysis highlights that despite of CO2 capture by the sorbent favorably modifies the thermodynamics
of syngas production, H2 dilution worsens the performance
of the sorption enhanced reforming of model H2/CH4 streams with respect to pure CH4. Results show a drop
of 17% for CH4 conversion and a reduction of 15.4% of the
captured CO2 on passing from pure methane to a H2/CH4 feed with a 40/60 molar ratio. However, on increasing
the heat capacity of the bed, by replacing part of the sorbent with
an inert heat carrier, better performances are calculated for the
H2/CH4 feed matching the pure CH4 case. The presence of C2+ hydrocarbons is assessed as well and the
results show a significant improvement in the reformer’s performance;
in the case of a stream composed of H2/CH4/C3H8 with a molar ratio 40/45/15, the total hydrocarbon
conversion grows to 92.8%, CO2 capture ratio to 82.6%,
and H2 purity to 95.6%. The positive effect is associated
with thermal factors that promote the reaction kinetics. Thus, the
suitability of the sorption enhanced reforming technology to H2-rich and C-poor streams is strictly composition dependent;
by cofeeding of C2+ hydrocarbons, the process turns into a remarkable
solution for converting gaseous streams in pure H2
Amides in Bio-oil by Hydrothermal Liquefaction of Organic Wastes: A Mass Spectrometric Study of the Thermochemical Reaction Products of Binary Mixtures of Amino Acids and Fatty Acids
Among biofuels, the bio-oil produced
by hydrothermal liquefaction
of waste biomass can be considered an alternative to fossil fuels
in industry as well as transport and heating compartments. The bio-oil
complex composition is directly dependent upon the specific biomass
used as feedstock and the process used for the chemical conversion.
The coexistence of proteins and lipids can explain, in principle,
the high percentage of fatty acid amides found in the produced bio-oil.
In the present study, the amides in a sample of bio-oil have been
separated by gas chromatography and identified at first on the basis
of their electron impact (EI) mass spectra. To distinguish between <i>N</i>-alkyl isomers, standard amides have been synthesized and
analyzed. Because the most reasonable origin of fatty acid amides
in hydrothermal bio-oils is the condensation reaction between fatty
acids and the decarboxylation products of amino acids, a series of
model experiments have been carried out by reacting hexadecanoic acid,
at high temperature and pressure, with each of the 20 amino acids
constitutive of proteins, looking for the formation of fatty acid
amides. Remarkably, by such experiments, all of the amides present
in the bio-oil have been recognized as hydrothermal coupling compounds
of the decomposition products of amino acids with fatty acids, thus
allowing for their structural elucidation and, also important, confirming
their (bio)Âchemical origin