The
decarboxylation of brown grease (BG) to green diesel hydrocarbons
over a 5 wt % Pd/C catalyst was investigated in semibatch and batch
reactors. Catalytic deoxygenation of BG under H2–Ar
occurs primarily via decarboxylation with the liquid products of primarily n-heptadecane and n-pentadecane. A 90%
conversion of BG in a semibatch mode was obtained in 7 h. In contrast,
in a batch reaction the conversion was roughly 40% in the same reaction
time. However, by pretreating the “as received” BG with
H2, the conversion in a batch reactor was increased 1.4-fold;
and when the H2 to BG ratio was increased to 3/1 (mol/mol),
the conversion was further improved. A complete conversion of BG into
green diesel via decarboxylation is possible over 5% Pd/C catalyst
at 300 °C and 1.5 MPa. This study demonstrates the feasibility
of obtaining valuable green diesel biofuel from waste oil.
The
hydrocracking of distillers dried grains with solubles (DDGS)
corn oil over bimetallic carbide catalysts was explored for green
diesel production. A catalyst composed of nickel–tungsten (Ni–W)
carbide supported on Al-SBA-15 was designed based on the ability of
nickel to adsorb and activate hydrogen and the potential of tungsten
for hydrogenation reactions. Four different Ni–W ratios (1:9,
1:1, 2:1, and 9:1) were prepared by the impregnation method to study
the effect of metal ratio on the catalyst structure, activity, and
selectivity. Catalyst activity was evaluated in a fixed bed reactor
at 400 °C and 650 psi (4.48 MPa) with a hydrogen flow rate of
30 mL min–1 and DDGS corn oil flow rate of
0.08 mL min–1. The catalysts showed significant
differences in activity and selectivity, with the catalyst having
a Ni–W ratio of 9:1 achieving 100% conversion of corn oil and
100% selectivity to diesel for 2 days. Results indicate that by minimizing
metal alloy formation and enhancement of the metal dispersion leads
to higher activity, selectivity, and durability of the catalysts.
A dendrimer-encapsulated nanoparticle (DENP) method was employed to
minimize alloy formation and increase the metal dispersion on the
support. The catalysts prepared by the DENP method showed activity
greater than that of the catalyst prepared by the impregnation method
for the hydrocracking of DDGS corn oil.
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