2 research outputs found
Single-Pot Reductive Rearrangement of Furfural to Cyclopentanone over Silica-Supported Pd Catalysts
Direct
one-pot hydrogenation of furfural (FFR) to cyclopentanone
(CPO) was investigated over different silica-supported Pd catalysts.
Among these, 4% Pd on fumed silica (4%Pd/f-SiO2) showed
remarkable results, achieving almost 98% furfural (FFR) conversion
with ∼89% selectivity and 87% yield to cyclopentanone at 165
°C and 500 psig H2 pressure. More interestingly, the
fumed-silica-supported catalyst tuned the selectivity toward the rearrangement
product, i.e., cyclopentanone, whereas all of the other supports were
found to give ring hydrogenation as well as side chain hydrogenation
products due to their parent Brönsted acidity and specific
support properties. X-ray diffraction data revealed the presence of
different phases of the face-centered cubic lattice of metallic Pd
along with lowest crystallite size of 15.6 nm in the case of the silica-supported
Pd catalyst. However, Pd particle size was found to be in the range
of 5–13 nm with even dispersion over the silica support, confirmed
by high-resolution transmission electron microscopy analysis. While
studying the effect of reaction parameters, it was observed that lower
temperature gave low furfural conversion of 58% with only 51% CPO
selectivity. Similarly, higher H2 pressure lowered CPO
selectivity with subsequent increase in 2-methyl furan and ring hydrogenation
product 2-methyl furan and 2-methyl tetrahydrofuran. Thus, as per
the requirement, the product selectivity can be tuned by varying the
type of support and/or the reaction parameters suitably. With the
help of several control experiments and the characterization data,
a plausible reaction pathway was proposed for the selective formation
of cyclopentanone
Tandem Synthesis of Glycidol via Transesterification of Glycerol with DMC over Ba-Mixed Metal Oxide Catalysts
Glycerol carbonate
(GC) and glycidol (GD) are commercial products
possible from glycerol transformation, which has become a subject
of great importance. Among several basic catalysts screened in this
work, BaO showed the highest glycerol conversion of 71% with almost
complete selectivity to GC. A tandem synthesis of GD with a selectivity
as high as 80% with 98% glycerol conversion could be achieved with
mixed oxides of Ba and lanthanides (La and Ce) prepared by the coprecipitation
method. Although BaO alone showed the highest basicity as measured
by CO<sub>2</sub> TPD, tuning of basicity by incorporation of CeO<sub>2</sub> resulted in the formation of GD. Incorporation of Ba into
the ceria matrix induced oxygen vacancies in the cerium oxide material.
The presence of u″/v″ doublets at 888.7 and 903.2 eV,
respectively, in XPS of the Ba–Ce sample also confirmed the
oxygen vacancies in the lattice. In this tandem approach to GD, the
subsequent decarboxylation of initially formed GC was due to the presence
of a CeO<sub>2</sub> lattice with defects, which is known to be the
best for CO<sub>2</sub> adsorption. Increase in both catalyst loading
and temperature showed a dramatic enhancement in GD selectivity. A
plausible reaction pathway for the transesterification of glycerol
with DMC to give GC followed by its decarboxylation to GD is also
proposed based on the structural characterization and activity studies