A continuous hydrothermolytic catalytic reactor system for the production of bio‐crude biofuels

Abstract

This work describes the continuous hydrothermal conversion of free fatty acid and triglyceride-based feedstocks to biofuel mixtures using metal oxide catalysts, supercritical water, and high temperatures ( ≥500 °C) in a fi xed bed reactor. A brief investigation of catalyst type indicated that zirconium dioxide (ZrO 2 ) resulted in a biofuel mixture with similar properties to petroleum fuel products and the catalyst was stable under the supercritical water conditions used. The biofuel product is comprised of alkanes, alkenes, aromatics, and ketones. A wide variety of feedstocks were investigated, as well as the effect of temperature on yield and conversion selectivity to biofuel. The temperature study led to the identifi cation of a set of ideal conditions (515 o C, 3:1 H 2 O:soybean oil mass ratio, ZrO 2 catalyst, 60 s catalyst contact time, 3500 psi) where liquid yield (70%) and selectivity (99%) were maximized as well as making a biofuel product with a useful combination of functionalities. Finally, the biofuel mixture was distilled, fi rst atmospherically and then under vacuum, to give a light fraction and a middle distillate fraction. The fractions were sent for ASTM D4814 or ASTM D975 quality testing to determine the similarities to their petroleum counterparts: gasoline (light distillate) and diesel (middle distillate). The ASTM results were promising as both biofuel distillates have similar properties to their petroleum counterparts, even meeting many of the ASTM testing specifi cations.In the Field: A continuous hydrothermolytic catalytic reactor system CV McNeff et al.In the Field: A continuous hydrothermolytic catalytic reactor system CV McNeff et al.

Hydrothermal catalysis of waste greases into green gasoline, jet, and diesel biofuels in continuous flow supercritical water

“…The full catalytic flow system description and liquid and gas product collection procedures have been previously described, along with a diagram (provided in the SI for convenient access) of the system apparatus components. 29…”

“…The biofuel products produced in this work were studied with the same spectroscopic techniques as described previously, 29 mainly using gas chromatography-mass spectrometry (GCMS), proton nuclear magnetic resonance ( 1 H-NMR), and Fouriertransform infrared (FTIR) analyses. Gas products were analyzed with headspace gas chromatography-mass spectrometry (HS-GCMS) and gas-phase FTIR spectroscopy.…”

“…To demonstrate that the titania catalyst could be regenerated, it was removed from the reactor after it was coked from use in producing biocrude and heated in a stream of oxygen at 400 °C for 3 h, as previously described. 29 The resulting material was re-evaluated for catalytic activity. Figure 7 shows that the resulting GCMS chromatogram of the biocrude produced with the reactivated catalyst was nearly identical to that from fresh titania.…”

“…The novel process described here has been reported previously, 29 but here we describe the production of sufficient fractions of green gasoline, green jet, and green diesel fuel to be used in engine and ASTM fuel test methods. This process offers the opportunity to use non-food, waste BG to produce renewable biofuels compatible with the present infrastructure.…”