1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 z Catalysis Low-Temperature Direct Catalytic Hydrothermal Conversion of Biomass Cellulose to Light Hydrocarbons over Pt/Zeolite Catalysts Shuhei Ogo,* [a] Yutaro Okuno, [a] Hikaru Sekine, [a] Shota Manabe, [a] Tomohiro Yabe, [a] Ayumu Onda, [b] and Yasushi Sekine [a] Direct catalytic hydrothermal conversion of cellulose to C 3 + C 4 hydrocarbons at a low temperature (443 K) over a Pt/zeolite catalyst without hydrogen or other expensive reagents was investigated. Pt supported on NH 4 + -form ultra-stable Y-type (NH 4 -USY) zeolite catalyst, which showed the highest activity among the tested Pt/zeolite catalysts, has appropriate acidity and a suitable active Pt site. The C 3 + C 4 hydrocarbon yield reached 14.5 C-% during the reaction over the Pt/NH 4 -USY catalyst at 443 K after 72 h of the reaction. Results showed that the acid strength of the zeolite support was an important factor affecting the cellulose decomposition activity. Because of their structural sensitivity, Pt/zeolite catalysts with Pt particles larger than 5 nm, including Pt/NH 4 -USY catalyst, showed higher TOF values than catalysts with Pt particles smaller than 5 nm. Introduction To cope with issues of diminishing fossil fuel resources and global environmental problems, renewable biomass resources are attracting attention as substitutes for fossil resources. Specifically, cellulose presents several important advantages that include large quantities present in the biosphere and there are no competitions with food productions. Nevertheless, cellulose utilization has remained limited because of its robust structure. Some processes use solid catalysts to resolve difficulties related to cellulose conversion into glucose, [1–7] chemical precursors, [8–13] and fuel. [14–16] Reportedly, glucose (and derivatives) can be converted into hydrocarbons using solid catalysts. [15–28] Conversion of sugar alcohols (obtained by hydro- genation of sugars) into light hydrocarbons with hydrogen over Pt/SiO 2 -Al 2 O 3 , [19,20] Pt/zirconium phosphate, [21,22] Pt-ReO x / C, [22] Pt/H-ZSM-5 (H + -form MFI-type zeolite), [10] Ni/H-ZSM-5, [23–26] or Ir-ReO x /SiO 2 reportedly combined with H-ZSM-5. [28] Tomishige et al. also reported that conversion of sorbitol to gasoline- ranged products including hydrocarbons without external hydrogen over Pt-modified Ir-ReO x /SiO 2 catalyst. [29] Recently, the direct conversion of lignocellulose or cellulose into hydro- carbons under hydrogen pressure has been reported. [7,13,16,28] Sels et al. reported that cellulose was converted directly into liquid straight-chain alkanes over Ru/C catalysts at 483 K with hydrogen (5.0 MPa). [30] Murata et al. reported that cellulose can be converted directly into C 2 –C 9 paraffins over Pt/zeolite catalysts (zeolite: H-ZSM-5(23) or H-USY(6.3); the number in parenthesis presents the SiO 2 /Al 2 O 3 ratio) at 673 K with hydro- gen (6.5 MPa). [16] Tomishige et al. reported one-pot conversion of cellulose to n-hexane (C 6 paraffin) over Ir-ReO x /SiO 2 (Re/Ir = 2) catalyst combined with H-ZSM-5(90) zeolite as a co-catalyst in a biphasic reaction system (n-dodecane + H 2 O) under a pressurized hydrogen atmosphere (6.0 MPa). [28,31] In the catalytic system, high-temperature water and/or H-ZSM-5 zeolite pro- mote the hydrolysis of cellulose to glucose via water-soluble oligosaccharides. Then hydrogenation and hydrogenolysis of glucose by the Ir-ReO x /SiO 2 and H-ZSM-5 produce hydro- carbons. This catalytic system was also applicable to the direct hemicellulose conversion into n-pentane. [32] Under these hydro- gen-pressurized conditions, although cellulose conversion and paraffin yields were high, much amounts of hydrogen were consumed. To avoid consumption of much amounts of valuable hydrogen, it was reported that using in situ generated hydro- gen by aqueous phase reforming of sugar alcohols was an effective way. [29] Previous reports described one-pot direct catalytic con- version of cellulose to light hydrocarbons, mainly including the important petrochemical feedstocks of C 3 and C 4 hydrocarbons, over Pt-supported zeolite catalyst at 443 K under hydrothermal conditions without external hydrogen or other expensive reagents. [33,34] Only Pt-supported catalyst showed activity for light hydrocarbon formation among metal (Pt, Pd, Cu, Ni, Co, Fe: 1 wt%)-supported catalysts. The zeolite structure and the state of supported Pt affected the activity and selectivity of the reaction. Especially, the Pt/H-USY(14) zeolite catalysts showed high activity and stability under the reaction conditions. However, the hydrocarbon yield remained low. Therefore, highly active catalyst and optimization of reaction conditions were developed. [a] Dr. S. Ogo, Y. Okuno, H. Sekine, S. Manabe, Dr. T. Yabe, Prof.Dr. Y. Sekine Department of Applied Chemistry Waseda University 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan E-mail: ogo@aoni.waseda.jp [b] Dr. A. Onda Research Laboratory of Hydrothermal Chemistry, Faculty of Science and Technology, Kochi University 2-5-1 Akebonocho, Kochi 780-8520, Japan Supporting information for this article is available on the WWW under https://doi.org/10.1002/slct.201701035 Full Papers DOI: 10.1002/slct.201701035 1 ChemistrySelect 2017, 2,1–6  2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim