Catalytic Hydrodeoxygenation of High Carbon Furylmethanes to Renewable Jet‐fuel Ranged Alkanes over a Rhenium‐Modified Iridium Catalyst

Abstract

Renewable jet-fuel-range alkanes are synthesized by hydrodeoxygenation of lignocellulose-derived high-carbon furylmethanes over ReO -modified Ir/SiO catalysts under mild reaction conditions. Ir-ReO /SiO with a Re/Ir molar ratio of 2:1 exhibits the best performance, achieving a combined alkanes yield of 82-99 % from C -C furylmethanes. The catalyst can be regenerated in three consecutive cycles with only about 12 % loss in the combined alkanes yield. Mechanistically, the furan moieties of furylmethanes undergo simultaneous ring saturation and ring opening to form a mixture of complex oxygenates consisting of saturated furan rings, mono-keto groups, and mono-hydroxy groups. Then, these oxygenates undergo a cascade of hydrogenolysis reactions to alkanes. The high activity of Ir-ReO /SiO arises from a synergy between Ir and ReO , whereby the acidic sites of partially reduced ReO activate the C-O bonds of the saturated furans and alcoholic groups while the Ir sites are responsible for hydrogenation with H .

Selective Hydrodeoxygenation of Vegetable Oils and Waste Cooking Oils to Green Diesel Using a Silica-Supported Ir-ReO x Bimetallic Catalyst

“…The conversion of stearic acid and the yields of C 18 alkaneincreasedwith an increase in Re/Ir molarr atio, indicating ah ighera mount of Re is beneficial to the HDO activity,w hich is consistent with previous studies of Ir-ReO x /SiO 2 catalyzed cellulose [36] and high carbon furylmethanes [39] HDO. The conversion of stearic acid and the yields of C 18 alkaneincreasedwith an increase in Re/Ir molarr atio, indicating ah ighera mount of Re is beneficial to the HDO activity,w hich is consistent with previous studies of Ir-ReO x /SiO 2 catalyzed cellulose [36] and high carbon furylmethanes [39] HDO.…”

“…[39] The results suggest lower reaction temperature and higherhydrogen pressure are beneficial for the selective production of the C 18 alkane. The conversion of stearic acida nd the yield of C 18 alkane increasea st he reaction temperature is increasedf rom 413 to 453 K( entries 1, 3, and 5).…”

“…[63] Pure stearic acid conversion gives two main products,1 -octadecanol and n-octadecane, and at race amount of n-heptadecane (Figure 2a). [39] However,t he peaks for Re are absent in Ir-ReO x /SiO 2 (Re/Ir = 3), suggesting that the Re species could be highly dispersed in the presence of Ir and that the high dispersityi st he reason for the enhanced performance of the bimetallic catalyst. The hydrogenolysis rate of 1-octadecanols peeds up after complete con-version of stearic acid.…”

“…[39] First, Ir/SiO 2 was prepared by impregnating Ir on SiO 2 (Fuji Silysia G-6, which was precalcined in air at 973 Kf or 1h at ah eating rate of 10 Kmin À1 ,B runauer-Emmett-Teller (BET) surface area 535 m 2 g À1 )b yu sing an aqueous solution of H 2 IrCl 6 (Sigma-Aldrich). [39] First, Ir/SiO 2 was prepared by impregnating Ir on SiO 2 (Fuji Silysia G-6, which was precalcined in air at 973 Kf or 1h at ah eating rate of 10 Kmin À1 ,B runauer-Emmett-Teller (BET) surface area 535 m 2 g À1 )b yu sing an aqueous solution of H 2 IrCl 6 (Sigma-Aldrich).…”

“…[66] The analysiss uggestsa significant portion of Re is partially reducedt oR e 2 + ,R e 4 + ,a nd Re 6 + (27 %, 17 %, and 4%,r espectively), which is consistent with our prior report of the Ir-ReO x /SiO 2 -catalyzed HDO of high-carbon furylmethanes. [39] Based on the reactionp erformance and characterization of the catalyst, we propose ac oncerted catalysis by Ir and highly dispersed ReO x (Scheme 2). However,the amountofmetallic Re (Re 0 )i st he same in the fresh and spent catalysts.…”