Hydrodeoxygenation of Isoeugenol over Carbon-Supported Pt and Pt–Re Catalysts for Production of Renewable Jet Fuel

Abstract

A series of monometallic platinum and bimetallic platinum−rhenium catalysts supported on mesoporous carbon Sibunit, which is a type of mesoporous, microcrystalline carbon, were investigated for hydrodeoxygenation (HDO) of isoeugenol (IE) at 200−300 °C and 30 bar of H 2 , using dodecane as a solvent. Catalytic activity was tested in a batch reactor to screen the catalysts and, for comparison, also in the continuous mode. For batch experiments, complete conversion, and a high yield of the desired product, propylcyclohexane (PCH), were obtained for all bimetallic PtRe/Sibunit in 240 min, with the highest yield of PCH when Pt:Re ratio was 1:1 or 1:3. The results for Pt−Re (1:1) were reproducible, in terms of catalytic activity and reusability of catalysts, which showed no deactivation. Monometallic Pt catalysts displayed low activity. Continuous experiments were performed with PtRe(1:1)/Sibunit at 30 bar H 2 , 0.5 mL/min of the liquid flow, and temperatures between 75 °C and 200 °C. The distribution of products showed deoxygenation at higher temperatures, while at lower temperatures, mainly oxygenated products were formed. XPS results confirmed the presence of ReOx species, where an increase in the platinum loading resulted in a decrease in the fraction of ReOx species and subsequently lower PCH yield.

Bifunctional Pt–Re Catalysts in Hydrodeoxygenation of Isoeugenol as a Model Compound for Renewable Jet Fuel Production

“…Monometallic catalysts displayed the lowest conversion of DH, 65% for Pt/C (entry 1) and 25% for Re/C (entry 2). Such low values are consistent with those reported in the literature for HDO using monometallic catalysts supported on carbon-type materials . Propylcyclohexane yields (PCH Y ) were also the lowest for these catalysts, while Pt/C displayed the highest yield of the hydrogenated intermediate (HYD) among all catalysts (Figure c).…”

“…These results are in accordance with microscopy and EXAFS results. The increase of acid sites for bimetallic catalysts can also help explain the presence of ReOx, which has been found to be important for deoxygenation …”

“…Catalysts used for HDO of biogenic compounds are often bifunctional, as they require a metal for hydrogenation and a solid acid support or a metal oxide with O-vacancies. , Studies on HDO catalysts were initially performed with sulfided NiMo and CoMo supported on Al 2 O 3 and SiO 2 used for hydrodesulfurization (HDS) due to obvious similarities between HDO and HDS . Recently, attention has shifted to non-sulfided monometallic and bimetallic catalysts on a variety of supports, such as different types of carbon (activated carbon, carbon black, Vulcan carbon), Sibunit, metal oxides (TiO 2 , ZrO 2 , CeO 2 ), and nanostructured materials (carbon nanotubes, SBA-15, and MCM-41) . The most studied metals for HDO include Ni, Mo, Co, Pt, Ru, and Pd …”

“…This combination of metals, however, has been scarcely used for HDO of isoeugenol. Our previous study on bimetallic Pt–Re catalysts supported on a mesoporous carbon (Sibunit) demonstrated an increased activity when compared to typical catalysts reported in the literature and used under similar reaction conditions . The previous investigation was limited regarding the effect of Re on isoeugenol HDO, as only three bimetallic catalysts with less variations of Pt and Re loadings were tested.…”

Advances in Upgrading Biomass to Biofuels and Oxygenated Fuel Additives Using Metal Oxide Catalysts

“…Direct hydrodeoxygenation of fats and oils to hydrocarbons, often known as green diesel, is also a very useful process to produce greater yield of better quality oil with higher carbon content. Biomass hydrodeoxygenation can be achieved using a variety of processes, such as hydrotreatment of bio-oils, − hydrogenolysis, pyrolysis, , aqueous-phase reforming, and hydrotreatment of carboxylic acids. Biodiesel is a user end product obtained after mixing with petrodiesel in different ratios.…”