SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Xiaoqing Huang,Haoyu Su,Ping Hu,Yueyuan Ye,Duo Wang
To fully utilized the high value-added phenolic compounds in biomass pyrolysis bio-oils, a heterogeneous extraction method was developed in this study to separate 4-ethylguaiacol, guaiacol, and eugenol from bio-oil one by one. Based on the high selectivity of coordination intermediates generated between Ca 2+ and phenolic compounds with hydroxyl and methoxy groups towards the parent phenol, the reaction intermediate between each of 4-ethylguaiacol, guaiacol, eugenol and Ca 2+ was used as the extracting agents. Influencing parameters investigated were the sequence of extracting three phenolic compounds from the model bio-oil, the optimal extraction conditions, and the Ca 2+ distribution in the original extracting agents at the end of the reaction. The optimal extraction sequence was determined to be 4-ethylguaiacol, eugenol and guaiacol through the evaluation of multiple experiments changing their addition sequence. Under the conditions of 25 °C reaction temperature, 45 min reaction time, and pH value of 7, the extraction efficiency of 4-ethylguaiacol, eugenol and guaiacol from bio-oil reached 60.6 %, 46.1 % and 60.7 %, respectively. Meanwhile, the purity of these three phenolic compounds achieved 62.4 %, 90.0 % and 89.0 %.
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INDUSTRIAL CROPS AND PRODUCTS
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2024
·
IF 5.6
Mengqing Zhou,Xialin Ji,Changzhou Chen,Liangliang Zhang,Jianchun Jiang
Through the utilization of diverse technological processes, lignin could be transformed into a multitude of valuable chemicals and fuels. This transformation not only reduces our dependence on fossil energy but also fosters the promotion of environmental sustainability. In this study, Ce metal was incorporated into the zeolite imidazolium framework-67 (ZIF-67) using the impregnation method to prepare a series of bimetallic catalysts . Using isopropanol solvent as the hydrogen source, guaiacol was effectively converted to cyclohexanol with over 80.0% selectivity over the optimum catalyst at 240 °C, 1.5 MPa N 2 , for 4 hours. The prepared catalysts were subjected to characterization methods such as BET, SEM, XPS , TEM , XRD , H 2 -TPR and NH 3 -TPD. The results of the characterization show that the addition of Ce changed the zeolitic imidazolium ester backbone structure of ZIF-67 and encouraged the emergence of more oxygen vacancies , which strengthened the catalyst hydrodeoxygenation activity and reducibility . Based on the findings of the catalytic performance tests and a retesting, the reaction pathway of the guaiacol hydrodeoxygenation process was suggested.
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CHEMICAL ENGINEERING JOURNAL
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2025
·
IF 13.2
Kai Dong,Di Zhao,Yang Pang,Binghui Liu,Qian Liu,Tong Mu,Chengji Zhao
Developing high-performance bio-based epoxy resin as an alternative to petroleum-derived bisphenol A epoxy resin (DGEBA) for manufacturing recyclable carbon fiber-reinforced polymers (CFRP) presents a formidable challenge. A novel epoxy monomer derived from 4-propyl guaiacol with significantly low viscosity was synthesized via a two-step process, followed by curing with 4,4′-dithiodianiline to yield a bio-based vitrimer featuring only reversible disulfide bonds. In contrast to DGEBA, this vitrimer alleviated concerns regarding the residual presence of bisphenol A and its derivatives while maintaining good thermal and mechanical stabilities. Furthermore, the flexible propyl side chains accelerated chain segment motions and synergistically enhanced the dynamic characteristics of this bio-based vitrimer with dynamic disulfide bonds. It demonstrated a much rapid stress relaxation of 15.8 s at 200 °C, facilitating the complete repair of scratches from epoxy resins and composite materials within 30 min under tiny pressure. The vitrimers could undergo reorganization four times while upholding chemical integrity and was readily achievable for closed-loop recycling. The low viscosity of the epoxy matrix facilitated the molding process of the composites resulting in high performance composites without diluents. The resulted carbon fiber reinforced polymer composite (CFRP) exhibited excellent mechanical characteristics and enabled reprocessing, self-repairing, and high-value, non-invasive fiber recycling. This research expands the dynamic attributes of epoxy vitrimer to CFRP, a pivotal step towards realizing multifunctional bio-based CFRP and facilitating the closed-loop recycling of composite materials.
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JOURNAL OF VINYL & ADDITIVE TECHNOLOGY
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2025
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IF 3.6
Huajun Duan,Ruian Li,Yuan Gao,Jiangtao Geng,Yuan Chen,Ya Li,Weipeng Liu,Huiru Ma
Epoxy resin (EP) is a thermosetting resin of significant commercial value. However, it is afflicted by inherent defects, including flammability and non-self-extinguishing properties. Consequently, it is imperative to modify EP with flame retardant additives. Currently, the majority of flame retardants are characterized by complexity and a cumbersome preparation process, which is not conducive to environmental sustainability. Consequently, there is a growing demand for eco-friendly bio-based flame retardants. In this paper, bio-based reactive flame retardants (HGD) with hydroxymethyl and phenolic hydroxyl groups were prepared in a one-step method by bulk reaction using the bio-based materials 5-hydroxymethylfurfural, guaiacol, and DOPO as raw materials, and were added into EP as co-curing agents to prepare flame retardant epoxy resins (FREPs). Comprehensive evaluation revealed fire safety improvements in HGD-modified EP systems. Specifically, the optimized EP/HGD-7.5 formulation demonstrated reductions in key combustion parameters compared to unmodified EP: 35.7% decrease in peak heat release rate (pHRR), 34.0% reduction in total heat release (THR), 24.3% lower average effective heat of combustion (Av-EHC), and 16.8% suppression of total smoke production (TSP). Meanwhile, the modified composites exhibited concurrent mechanical enhancement. At 7.5% HGD loading, flexural strength and modulus increased by 21.1% and 20.0%, respectively, while tensile performance optimization occurred at 5.0% loading with 20.6% strength improvement and 24.5% modulus elevation. Notably, HGD-modified EP systems maintained superior thermal stability. The glass transition temperature ( T g ) of EP/HGD-7.5 is 154.2°C, exceeding that of EP. This investigation successfully demonstrates a sustainable approach for developing multifunctional epoxy composites with enhanced fire resistance and mechanical performance through bio-based modification.
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Molecular Catalysis
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2025
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IF 4.9
Zong-Pin Fu,Qi-Jie Zhou,Yun-Peng Zhao,Yu-Fa Wu,Fang-Jing Liu,Mei Zhong,Jian Li,Jing Liang,Jing-Pei Cao
The high oxygen content and low calorific value of bio-oil make it unsuitable for direct production of high energy density fuels. To address this issue, the C-O-C, C-O-H, and C-C bonds in the oxygenated compounds of bio-oil can be modified through hydrodeoxygenation (HDO) reaction. In this study, we synthesized a series of efficient Ni-CoOx/Hβ-u catalysts by impregnating Hβ molecular sieve modified with urea under mild conditions. The catalytic HDO performance of these catalysts was evaluated using guaiacol and dealkalized lignin oil as substrates. The results indicate that the Ni-15CoOx/Hβ-u catalyst demonstrated superior activity. The suitable specific surface area and pore volume of the Ni-15CoOx/Hβ-u catalysts, as well as uniformly dispersed metal particles on their surface, increased the number of active sites available for HDO. Additionally, the presence of defective sites on the CoOx surface and acidic sites on the catalyst facilitate the breaking of intermediate C-O bonds (deoxygenation) and dehydration reactions. Utilizing the Ni-15CoOx/Hβ-u catalysts, guaiacol was completely converted to cyclohexane with 100% selectivity (at 180 °C, 1.0 MPa H 2 , 40 min). Furthermore, the phenolic compounds in bio-oil could also be transformed into cycloalkanes via the HDO process. These findings suggest that the Ni-15CoOx/Hβ-u catalyst has the potential to effectively hydrodeoxygenate bio-oil under mild reaction conditions.
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Journal of Environmental Sciences
·
2025
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IF 6.3
Jiayi Wang,Rui Zeng,Jun He,Chengjun Wang
The mechanisms and kinetics of the formation of aqueous secondary organic aerosol ( aq SOA) via photosensitive water-soluble matters (WSM) mediated photo-aging process of dissolved methoxyphenols, using guaiacol (GUA) as a model compound, in sunlit atmospheric aqueous phase were investigated. The occurrences and optical indices of typical photosensitive WSM, including both water-soluble inorganic matter (WSIM) and water-soluble organic matter (WSOM), in aqueous aerosol extracts were characterized and determined by using a variety of instrumental techniques. The results shown that various photosensitive WSIM and WSOM occur in atmospheric aqueous aerosol. The photolysis of WSM can generate abundant reactive oxygen species (ROS) and 3 WSOM*, which play equally important roles in entire GUA transformation process leading to aq SOA formation. Of those, the 3 WSOM* is the predominant contributor for initial GUA transformation due to its high [ 3 WSOM*] ss of 5.35 ± 0.12 × 10 −13 mol/L, generation rate of 3.43 × 10 −7 mol/(L·s), quantum yield of 4.86 %, and the rate constant of reaction with GUA over ∼10 9 L/(mol·s). Meanwhile, the ROS are key reactive species reacting with soluble intermediates of GUA transformation to produce final insoluble substances such as ether and low-volatile phenols, which are major constituents of formed aq SOA in aqueous extracts of aerosols. This work sheds the deeper insights into the mechanisms and kinetics on aq SOA formation via indirect phototransformation of dissolved methoxyphenols in real atmospheric aqueous phase.
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JOURNAL OF CATALYSIS
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2025
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IF 6.5
Xin Han,Shanguang Xu,Fan Zhang,Ruiying Chai,Shanguo Du,Xiuling Jiao,Dairong Chen,Jie Zhang
Modulation of the surface properties on catalyst support for selective hydrogenation with high activity and selectivity is a significant but challenging topic. Herein, we report the promotion of basic sites on MgO surface on the selective hydrodeoxygenation (HDO) of guaiacol to phenol. The results showed that basic MgO support could inhibit the further breaking of C–O bond of generated phenol compared to acidic support, which facilitated the formation of phenol with high selectivity. The catalytic activity of Pt/MgO catalysts was markedly influenced by the concentration and types of basic sites on the catalyst surfaces. The increase in the concentration of basic sites on the catalysts surface led to a linear increase in the conversion of guaiacol, and the selectivity (92 %) of phenol was achieved with >99 % conversion at the conditions of 280 °C and 0.1 MPa H 2 pressure. The characterization of catalysts, combined with the kinetic analysis, demonstrated that the strong basic sites generated by isolated O 2− species on the MgO surface could significantly enhance the adsorption of guaiacol, and improve the dispersion and electronic density of Pt species through the interaction of basic sites and Pt species, thereby further promoting the hydrogen dissociation, which achieved the excellent catalytic performance and stability by the dual active sites of basic sites and Pt sites. This study provides a promising strategy for the design of supported metal catalysts with improved surface basic sites for the selective HDO reactions of oxygenates.
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FUEL
·
2021
·
IF 6.609
Zhipeng Tian,Xuebin Liang,Rongxuan Li,Chao Wang,Jianping Liu,Libin Lei,Riyang Shu,Ying Chen
Catalytic hydrodeoxygenation (HDO) is a popular route to upgrade the pyrolysis lignin-oil that is abundant of phenolic compounds, and the synergistic effect of bimetal enables to improve the catalytic activity significantly. In this work, a series of non-noble metal catalysts are synthesized and their HDO performances of guaiacol are compared. Optimized NiCo/SiO 2 -ZrO 2 catalyst expresses a 100% conversion and a 99.9% selectivity of cyclohexane product, which is higher than those over Ni/SiO 2 -ZrO 2 catalyst. Catalyst characterization results demonstrate that the interaction between Ni and Co promotes the reduction of metal site and the adsorption of hydrogen, which is the crucial factor during HDO process. Besides, the electron transfer from Co to Ni species weakens the C-O bond of substrate intermediate and results in its cleavage to transform cyclohexanol to cyclohexane. This is also the rate determining step in the HDO of guaiacol. Specific kinetic study is conducted to verify the reaction pathway and the structure–activity relationship. The HDO reaction of guaiacol on NiCo/SiO 2 -ZrO 2 fits the first order kinetic model well. The apparent E a of 55.9 kJ·mol −1 is lower than those of the noble metal catalysts reported in previous studies. In addition, the upgrading of raw pyrolysis lignin-oil on this non-noble bimetallic catalyst also achieves a high HDO efficiency, with the hydrocarbon contents increased from 4.2% to 60.6%. The good HDO performance of this cheap and easy-prepared NiCo catalyst proves its promising potential in the upgrading of lignin-oil for the production of hydrocarbon fuels.
研究领域:
能源化学
·
催化科学
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ChemistrySelect
·
2024
·Vol. 9
·期 38
·e202402768
·
IF 1.9
Guangfei Qu,Yun Zhang,Junyan Li,Zhishuncheng Li
Graphical Electrochemically catalyzed ionic liquid technology facilitates lignin cleavage at 230 °C, with vanillin yields reaching 88.54 % at 3 V and guaiacol yields at 48.24 % at 4 V, showcasing enhanced productivity in lignin-derived compounds. Significant attention has been devoted to using biomass as a renewable resource to address the energy crisis and mitigate environmental pollution. Biomass, a potential substitute for fossil fuels, contains a substantial amount of lignin, ranging from 10 % to 25 %. Hence, it is crucial to research lignin depolymerization. In this study, the use of electrochemically catalyzed ionic liquids enabled the cracking of lignin at low temperatures. Specifically, by applying a low voltage at 230 °C, the controlled generation of vanillin and guaiacol was achieved. The concentration of vanillin in the depolymerized lignin reached 88.54 % under 3 V conditions. Similarly, it is presumed that the yield of guaiacol at 4 V is 48.24 %. These findings have significant implications for the targeted management of lignin depolymerization byproducts. Ultimately, this project establishes a framework for the high-value utilization of biomass and provides new perspectives on addressing the energy problem and environmental degradation.
研究领域:
生物质能
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有机化学
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环境科学
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ACS Catalysis
·
2022
·
IF 13.7
Ping He,Qisong Yi,Huawei Geng,Yuanchao Shao,Meng Liu,Zhijie Wu,Wenhao Luo,Yuanshuai Liu,Valentin Valtchev
Liquid-phase hydrodeoxygenation (HDO), catalyzed by metal or metal-acid sites, provides an effective catalytic strategy to remove oxygen-containing functionalities of lignin-derived phenolic compounds on the route to fuels and chemicals. Developing the catalyst with high activity and stability is crucial for such a chemical process but still remains a significant challenge. In this contribution, highly dispersed subnanometric Ru metal clusters (<1.5 nm) encapsulated in the cavities of MWW zeolites, including HMCM-22 and its siliceous analog ITQ-1, have been developed for the HDO of guaiacol, an important lignin-derived phenolic monomer, in an apolar liquid phase under mild conditions (160 °C, 3 MPa H2). We validate the effective encapsulation of Ru metal clusters in ITQ-1 and HMCM-22 zeolite cavities via complementary characterization methods. The detailed reaction pathways of the HDO of guaiacol are depicted by using guaiacol, phenol, and anisole as reactants. The subnanometric Ru metal clusters confined in MWW zeolite thin layers (20–30 nm in thickness) show remarkable enhancement in HDO activity compared to the large metal particles. The close proximity between Ru metal clusters and Brønsted acid sites (BAS) confined in zeolite constraints delivers a synergistic effect, leading to an additional enhancement in catalytic activity as well as product selectivity. The super stability of the ultrafine Ru metal clusters against sintering and leaching after successive catalytic runs is achieved. The well-defined mono- or bifunctional Ru-containing MWW zeolite catalysts enable the fundamental understanding of HDO of lignin-derived phenolic compounds in the apolar liquid phase and also provide a prototype for the design of superior catalysts for other energy-related transformations.
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Journal of Cleaner Production
·
2017
·
IF 5.715
De-Bin Li,Yun-Quan Liu,Yue-Yuan Ye,Shui-Rong Li,Duo Wang
Experiments were conducted to elucidate the mechanism of reaction between guaiacol and Ca(OH) 2 in water based on in situ FT-IR, 1 H NMR, ICP-AES and TGA analyses. Three phases were revealed for this reaction when guaiacol was dropped into the solution of Ca(OH) 2 , and the final molar ratio of guaiacol to Ca 2+ reaches 4. It was found that an acid–base reaction occurs in the first reaction phase. However, the second reaction phase includes not only the acid-base reaction, but also the accompanied coordination reaction between oxygen atom of hydroxyl group in guaiacol and Ca 2+ . The third reaction phase is also the coordination reaction, particularly, the one between the hydrogen atom in guaiacol and Ca 2+ . Based on the mechanism study, a novel circulating precipitation agent was developed and tested for the extraction of phenolic compounds from the simulated wastewater. The result showed that 96.63% guaiacol could be extracted from the simulated wastewater with the novel extraction technology at the optimum reaction conditions.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2017
·Vol. 409
·期 10
·2531-2537
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IF 3.431
Cheng Hao,Wu Shubin,Huang Jinbao,Zhang Xiaohua
Although o -quinonemethide (6-methylene-2,4-cyclohexadien-1-one) has been proposed as a key intermediate in char formation during the pyrolysis of guaiacol (2-methoxyphenol), direct evidence of this (e.g., spectroscopic data) has not yet been provided. Using in situ FTIR spectroscopy, the pyrolysis of guaiacol was investigated from 30 °C to 630 °C at 40 °C/min. The IR profiles showed direct evidence of o -quinonemethide production at about 350 °C, which vanished rapidly at around 420 °C in the vapor phase, indicating char formation. In addition, at 400 °C, salicyl aldehyde was observed, which decomposed slowly at about 500 °C. In combination with the known products of guaiacol pyrolysis, these results allowed the major reaction pathways of guaiacol pyrolysis to be discerned. Density functional theory calculations were performed, and the results were found to be in good agreement with the experimentally obtained IR profiles. These findings provide guidance on how to suppress secondary reactions of guaiacol during lignin pyrolysis.
On-line analysis of pyrolysis process of guaiacol using in situ FTIR
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