Synergistic Effect of EtOAc/H₂O Biphasic Solvent and Ru/C Catalyst for Cornstalk Hydrolysis Residue Depolymerization

Abstract

An EtOAc/H2O biphasic solvent–Ru/C coupling biorefinery process was developed to selectively produce aromatics from cornstalk hydrolysis residue (CHR). In this process, CHR was depolymerized in an ethyl acetate (EtOAc)/H2O biphasic solvent system over Ru/C catalyst, which produced aromatics and carbohydrates instantly separated by EtOAc and H2O. Most lignin in CHR was converted to aromatics and nonvolatile fractions, accompanied with partial degradation of cellulose. Optimized results showed that more than 42.7% of aromatics can be obtained under 260 °C for 5 h without external hydrogen pressure. Monophasic and biphasic parallel experimental results show that the strong lignin dissolving ability of the biphasic dissolution/separation system is helpful for aromatics production and separation, which promoted CHR depolymerization over Ru/C. Furthermore, CHR, products, depolymeirzation residue solid (DRS), and catalysts were carefully characterized by gas chromatography (GC-MS), Fourier transform infrared (FT-IR), gel permeation chromatrography (GPC), high-performance liquid chromatrography mass spectrometry (HPLC-MS), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Results demonstrated that the biphasic solvent–Ru/C coupling process can significantly alleviate repolymerization reactions. Based on these analysis results, the catalytic process in biphasic EtOAc/H2O was discussed. This work demonstrates that such a green biphasic catalytic/separation coupling system highlights a promising route for efficient biomass degradation and product separation at mild conditions without external hydrogen pressure.

First insights of SHVO catalyst activity for monomeric phenol production from olive pomace

“…The sums of the yields obtained for 4‐propylguaiacol/syringol in our study were lower than (15 and 28%), in the range of (3.1%) or presumably higher than (the yields were not reported in the respective studies) those of previous works. Nonetheless, as mentioned above, the yields are highly dependent on multiple factors (e.g.…”

“…In similar experiments performed on several types of biomass under nitrogen atmosphere (e.g. 2 < t <6 h, 150 < T < 300 °C), the reported pair ‘phenol yield/catalyst’ was 6.5% (Ru/C), 22% (Ru/C), 13–24% (Ru/C), 15–20% (carbonaceous solid acid catalyst) and 34% (Co‐phen/C) . The monomer yields were highly disperse between studies, and one parameter affecting the most is the nature of the substrate.…”

Metal-alkali catalytic valorization of lignocellulose towards aromatics and small molecular alcohols and acids in a holistic approach

“…Apparently, the biphasic n-butanol/H 2 O provided higher lignin oil and monomer aromatic yields compared to either pure n-butanol or pure H 2 O, which is consistent with deopolymerizatin lignin in ethyl acetate/H 2 O [43][44] , methanol-H 2 O [45][46] and ethanol-H 2 O [44,46] . On the other hand, the molecular weight of aqueous phase product is lower for the reaction in water than in biphasic solvent system (Fig.…”

“…Meanwhile, with the presence of Mg(OH) 2 , lactic acid also produce from the direct decomposition of glycerin, and the decomposition of lactic acid could lead to the production of formic and acetic acids [57,61] . Some of acetic acid and formic acid may also come from the depolymerization of lignin [43][44] .…”

In situ synthesis of biomass-derived Ni/C catalyst by self-reduction for the hydrogenation of levulinic acid to γ-valerolactone

“…To relieve the stress of fossil energy shortage, biomass is regarded as a substitutable resource which has enormous potential [1][2][3][4][5] . It is currently explored for the production of added-value chemicals and alternative fuels through bio-refinery [6][7][8] . Platform molecules, prepared through biomass raw materials, are particularly valuable [9] .…”