Article pubs.acs.org/IECR
Facile Production of 5‑Hydroxymethyl-2-Furfural from Industrially Supplied Fructose Syrup Using a Wood Powder-Derived Carbon Catalyst in an Ethylene Glycol-Based Solvent Bora Kim,†,§ Churchil A. Antonyraj,† Yong Jin Kim,†,‡ Baekjin Kim,†,‡ Seunghan Shin,†,‡ Sangyong Kim,†,‡ Kwan-Young Lee,§ and Jin Ku Cho*,†,‡ †
Green Process and Materials R&D Group, Korea Institution of Industrial Technology (KITECH), 89 Yangdaegiro-gil, Ipjang-myeon, Cheonan, 331-822 Chungnam, Korea ‡ Department of Green Process and System Engineering, University of Science and Technology (UST), 89 Yangdaegiro-gil, Ipjang-myeon, Cheonan, 331-822 Chungnam, Korea § Department of Chemical and Biological Engineering, Korea University, 5-1 Anam-dong, Seongbuk-ku, Seoul 136-713, Korea ABSTRACT: Petroleum-independent and economically viable production of 5-hydroxymethyl-2-furfural (HMF) from industrially supplied high fructose corn syrup (HFCS) using a wood powder-derived carbonaceous solid acid in an ethylene glycol (EG)-based solvent was developed. EG-based solvents were preferable to the dehydration of HFCS into HMF owing to stabilizing reversible intermediates. In addition, low boiling EG-based solvents were readily removed to isolate HMF. As a parametric study on the dehydration of HFCS into HMF in an EG-based solvent, effects of reaction temperature, initial concentration of fructose, catalyst dosage, and water content on reaction rate and HMF yield were investigated. Sulfonated amorphous carbonaceous materials (∼0.7 mmol of SO3H/g) were prepared from wood powder via incomplete hydrothermal carbonization and then sulfonization, and they were applied to the dehydration of HFCS in glyme, affording HMF in 80% yield. It was also found that a prolonged reaction enabled further conversion of HMF into levulinic acid in a highly selective manner.
1. INTRODUCTION For the past century, oil refineries have been well established, and hence the current organic chemicals ranging from commodity chemicals to fine chemicals mostly depend on petroleum. Recently, rising oil prices and global warming by CO2 have exerted pressure on the petroleum-dependent chemical industry.1 Many efforts are therefore dedicated to replacing irreversible petroleum with renewable and sustainable biomass.2 Biomass-derived carbohydrates regenerated by photosynthesis are the most abundant carbon source on earth. Hexoses from biomass-derived carbohydrates can be dehydrated to give 5-hydroxymethyl-2-furfural (HMF) with all carbon atoms retained. HMF is a versatile platform chemical, leading to valuable chemicals and fuels, thus it was listed as one of the top 10 biobased chemicals by the DOE.3 However, industrial production of HMF is still unaccomplished although a variety of fascinating methods have been explored.4 Many studies have focused on conversion efficiency of biomassderived carbohydrates into HMF, whereas less effort has been devoted to cost-competitive preparation and isolation of HMF. We, therefore, set criteria for economically viable production of HMF as follows: (i) the starting material is readily available and directly used as supplied; (ii) the solvent system is simple, inexpensive, and recyclable; (iii) the catalyt is easily prepared and recyclable. With a mechanistic point of view, ketofuranoses like fructose are beneficial to the selective dehydration into HMF because isomerization from aldehyde at C1 to ketone at C2 is unnecessary. The industrial manufacturing process of fructose has already been well-developed.5 Fructose is produced from © 2014 American Chemical Society
glucose by enzymatic conversion using xylose isomerase, and it is supplied in a syrup form (containing 25 wt% water) called high fructose corn syrup (HFCS). Therefore, a large quantity of HFCS is purchasable in the market, and direct use of HFCS is able to save the cost on the drying process for powdered fructose. In this context, HFCS can be practically evaluated as a reasonable substrate for the economically viable production of HMF. In the dehydration of fructose into HMF, solvent plays a pivotal role. Meanwhile, a choice of solvent is very limited, especially for a single-phase system because fructose is difficult to dissolve in most organic solvents. HMF synthesis from fructose was performed under aqueous conditions in the early stage of research. However, rehydration by excess water inevitably caused low conversion of fructose and subsequent hydrolysis of produced HMF resulting in the formation of a byproduct such as levulinic acid, formic acid, and polymer compounds,6 even in subcritical water with a low dielectric constant.7 To overcome such problems in aqueous systems, biphasic systems using a low boiling extracting solvent were developed with both homogeneous8 and heterogeneous9 catalysis, expecting in situ recovery of HMF produced during the reaction, but partition coefficient of HMF in extraction layer (organic layer) is insufficient because of HMF solubility in a broad of solvents. In addition, the process design of biphasic Received: Revised: Accepted: Published: 4633
January 22, 2014 February 27, 2014 March 3, 2014 March 3, 2014 dx.doi.org/10.1021/ie500303e | Ind. Eng. Chem. Res. 2014, 53, 4633−4641
Industrial & Engineering Chemistry Research
Article
2. MATERIALS AND METHODS 2.1. Materials. High fructose corn syrup 90 (HFCS, containing 90 mol % fructose out of total sugars) and wood powder (pine tree, 50−100 μm in diameter) were supplied by SK Chemicals Co. Ltd. (Korea) and G-Biotech (Korea), respectively. The components of wood used in this experiment are 42.7% of cellulose, 21.9% of hemicelluloses, 31.4% of lignin, and 0.7% of ashes. Zeolite Y (CBV 720, SiO2/Al2O3 mole ratio of 30, surface area of 780 m2/g) and zeolite β (CP811C-300, SiO2/Al2O3 mole ratio of 360, surface area is 620 m2/g) were supplied by Zeolyst International Inc. (USA) in its hydrogen form. Difructofuranose dianhydride was purchased from Wako Chemicals (Japan). Amberlyst-15 (hydrogen form, 4.3 mmol of −SO3H per gram resin), Nafion (hydrogen form), sulfuric acid (H2SO4, 30% free SO3), p-toluenesulfonic acid monohydrate (p-TSA, ≥98.5%), sodium hydrogen sulfate (NaHSO4), 1,4dioxane (anhydrous, 99.8%), ethylene glycol dimethyl ether (monoglyme, anhydrous, 99.5%), diethylene glycol dimethyl ether (diglyme, anhydrous, 99.5%), triethylene glycol dimethyl ether (99%), 1,3-dioxane (97%), tetrahydropyran (anhydrous, 99%), and 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) were purchased from Sigma-Aldrich (USA) and directly used without any further purification. All other general chemicals including ethyl acetate, ethanol, acetone, magnesium sulfate (MgSO4), and sodium hydroxide (NaOH) were obtained from Fisher Scientific (USA) and Samchun Chemicals (Korea). 2.2. Analytical Techniques. Reactions were monitored by HPLC (Agilent 1200 series) equipped with auto sampler (G1329A, Agilent), column temperature controller (G1316A, Agilent), and detector (G1315D for UV and G1362A for RID, Agilent) using ion-exclusion column (Bio-Rad Aminex HPX87H 300 × 7.8 mm) and processed by ChemStation software. HPCL analysis was performed under the following conditions: eluent, 0.01 N H2SO4; flow rate, 0.6 mL/min; column temperature, 45 °C. Synthetic HMF was characterized by HPLC and confirmed by 1H NMR (400 MHz, JNM-AL400, Jeol) processed by Delta program (ver. 4.3.6). The specific surface area was determined on a BET surface analyzer (ASAP2010, Micromeritics) using N2 as the adsorbent at liquid nitrogen temperature (77 K). The surface area was determined by the multipoint BET method using the adsorption data in the relative pressure (P/P0) range of 0−0.25. The powder samples were degassed in air over 12 h at 100 °C prior to analysis. The prepared sulfonated amorphous carbonaceous materials were analyzed by an FT-IR spectrophotometer (Nicolet 6700, Thermo Scientific system, USA). Attenuated total reflectance (ATR) equipment (Smart Miracle, Thermo Electron Corp, USA) was used for sample preparation, and spectra were obtained by averaging 32 scans from 4,000 to 800 cm−1 at 8 cm−1 resolution. The temperature and relative humidity for the analysis were 25 °C and 45%, respectively. The calculated spectra represented the transmittance. XPS measurements were carried out on Therma Scientific K-alpha using monochromatized Al Kα radiation (hν = 1486.6 eV) and processed using Thermo Avantage software. CHNS elemental analysis for sulfonated amorphous carbonaceous materials (AC−SO3H) was conducted using an inductively coupled plasma emission spectrometer (ICP, Shimadzu ICPS-7510). Acid/base titration of AC−SO3H was followed by a previous report.21 AC−SO3H (1 g) was contacted (145 rpm) with 0.1 N NaOH solution (150 mL) overnight at room temperature, and the supernatant
systems is more complicated than that of a single-phase system. In a single-phase system using an organic solvent in the presence of heterogeneous acid catalysts, aprotic polar solvents such as dimethyl sulfoxide (DMSO),10 N,N-dimethylformamide (DMF),11 N,N-dimethylacetamide (DMA),12 N-methyl2-pyrrolidone (NMP),12 and sulfolane13 were mainly attempted, and considerable yields of HMF could be achieved. There is, however, difficulty in removing and recycling them owing to high boiling points. Ionic liquids were also applied to the preparation of HMF from fructose in a successful manner.14 However, ionic liquids are unaffordable for large scale production of commodity chemicals for the time being, and recovery of HMF from ionic liquid is not quite efficient. On the other hand, despite easy removal and reusability, little effort was devoted to a single-phase system using a low boiling organic solvent (
