Furfuryl alcohol

Nickel(ii) chloride hexahydrate (NiCl₂·6H₂O), tin(ii) chloride dihydrate (SnCl₂·2H₂O), active carbon (S_BET = 815 m² g⁻¹), MgO, and commercial aluminum hydroxide (c-AlOH) were purchased from WAKO Pure Chemical Industries, Ltd. and used as received unless otherwise stated. g-Al₂O₃ (S_BET = 100 m² g⁻¹) was purchased from Japan Aerosil Co. Furfural (98%), furfuryl alcohol (97%), 2-methylfuran (98%), and tetrahydrofurfuryl alcohol (99%) were purchased from Tokyo Chemical Industry, Ltd. All organic chemical compounds were purified using standard procedures prior to use.⁵⁵

Furfuryl alcohol, 1,2‐PeD, cyclopentanone, and cyclopentanol were purchased from Tokyo Chemical Industry Co. TetrahydroFurfuryl alcohol (THFA), 1,4‐pentanediol (1,4‐PeD), and 2‐methyltetrahydrofuran were purchased from Sigma–Aldrich Co. 1,5‐PeD was purchased from Wako Pure Chemical Industries.
Charcoal‐supported Pd, Pt, Rh, and Ru (5 wt % metal loading; designated Pd/C, Pt/C, Rh/C, and Ru/C, respectively) and alumina‐supported Ru (5 wt % metal loading; designated Ru/Al₂O₃) were purchased from Wako Pure Chemical Industries.
Ruthenium (III) nitrosyl nitrate (Ru(NO)(NO₃)₃) solution in dilute nitric acid was purchased from Sigma–Aldrich Co. Zirconium oxide (ZrO₂) was obtained from Daiichi Kigenso Kagaku Kogyo Co. via the Catalysis Society of Japan (JRC‐ZRO‐7). Magnesium oxide (MgO) was obtained from Ube Industries via the Catalysis Society of Japan (JRC‐MGO‐3 1000 A). Cerium oxide (CeO₂) was obtained from Kanto Chemical Co. Titanium dioxide (TiO₂) was obtained from Degussa (P‐25). Graphite powder was obtained from Timrex (HSAG300). H‐ZSM‐5 powder (SiO₂/Al₂O₃=60) was purchased from JGC Catalysts and Chemicals.

Green coffee beans (C. arabica Sitio Chapada from Brazil and C. robusta from Vietnam) were purchased from Trini Coffee (Goyang, Korea). DL-Malic acid (≥98%), citric acid (≥98%), L-(+)-tartaric acid (≥99.5%), and succinic acid (≥99%) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Green coffee beans and organic acid powder were stored at room temperature.
For the analysis of volatile flavor compounds, C7 − C40 n-alkane standard and a divinylbenzene/Carboxen/Polydimethylsiloxane (50 μm DVB/CAR/PDMS) solid-phase microextraction (SPME) fiber were purchased from Supelco, Inc. (Bellefonte, PA, USA). Hexane, high-performance liquid chromatography (HPLC)-grade water, and HPLC-grade ethyl acetate were purchased from J.T. Baker (Philipsburg, NJ, USA). Sodium chloride (NaCl) was purchased from Samchun (Seoul, Korea). Quinoxaline, 2-methyl pyrazine, 2,5-dimethyl pyrazine, 2,6-dimethyl pyrazine, ethyl pyrazine, 2-ethyl-6-methyl pyrazine, furfural, 2-acetyl furan, furfuryl acetate, 5-methyl furfural, and furfuryl alcohol were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan).
For the analysis of α-DCs, MGO (purity 40%), DA (purity 97%), o-phenylenediamine, and 1-methylpyrazole were purchased from Sigma-Aldrich. GO (purity 39%) was purchased from Tokyo Chemical Industry Co., Ltd. HPLC-grade water and HPLC-grade ethyl acetate were purchased from J.T. Baker.