Conversion of Glycerol to Hydrocarbon Fuels via Bifunctional Catalysts

Abstract

Utilization of byproduct glycerol improves biodiesel production in terms of both economics and sustainability. Conversion of glycerol to hydrocarbon (GTH) fuels is among the promising options, which provides additional renewable energy besides biodiesel and contributes further to independence from fossil fuels. In the present work, bifunctional catalysts (Pt/H-ZSM-5 and Pd/H-ZSM-5) were selected, prepared, characterized, and tested for GTH conversion. The addition of noble metals enhances aromatics’ yield, and both catalysts convert GTH fuels effectively. On the basis of the experimental observations and prior literature, it is proposed that GTH conversion follows sequential hydrodeoxygenation and aromatization steps. Under optimized conditions, ∼90% glycerol conversion and ∼60% yield of aromatic hydrocarbons were achieved over the Pd/H-ZSM-5 catalyst.

Kinetics of glycerol conversion to hydrocarbon fuels over Pd/H‐ZSM‐5 catalyst

“…As described in our prior work, oxygenates (acrolein, acetol, etc.) were primary products when unsupported H‐ZSM‐5, Pd/SiO 2 (amorphous) and Pt/SiO 2 (amorphous) were used as catalysts, although the use of H‐ZSM‐5 promoted the formation of target products, aromatic hydrocarbon fuels.…”

“…As the same Pd/H‐ZSM‐5 catalyst, as in our prior publication, was used in the present work, results of catalyst characterization, including BET specific surface area, mean pore diameter, Pd metal dispersion (by H 2 O 2 titration), Pd particle size, AEC‐ICP element analysis, NH 3 ‐TPD, transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), and X‐ray powder diffraction (XRD), can be found in that publication and its Supporting Information. Briefly, the high BET surface area (437 m 2 /g) and moderate mean pore diameter (about 0.5 nm) of Pd/H‐ZSM‐5 indicates good accessibility of reactants (e.g., glycerol, acrolein, and olefin gases) over Pd/H‐ZSM‐5 catalysts.…”

“…The experiments were conducted in a continuous fixed‐bed reactor system, described in our prior work . The catalysts were packed in a stainless steel fixed‐bed reactor (with internal diameter 10 mm).…”

“…With its current cheap and ready availability, conversion of glycerol to hydrocarbon (GTH) fuels would increase the economic value of glycerol and provide an additional bioenergy source. In our recent work, bifunctional catalysts (Pt/H‐ZSM‐5 and Pd/H‐ZSM‐5) were selected, prepared, characterized, and tested for GTH conversion. Under optimal conditions, about 90% glycerol conversion and 60% yield of aromatic hydrocarbons were achieved over Pd/H‐ZSM‐5 catalyst.…”

“…For such complex reaction networks, containing a large number of chemical species, lumped kinetic models are typically developed to represent the overall reaction pathways, which can be further used for reactor design and process scale‐up. In the present study, based on our prior work, differential kinetic experiments of GTH conversion are reported, a lumped kinetic model is developed, and reaction mechanism is discussed.…”