Browsing by Author "Li, Yongdan"
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Item A 98.2% energy efficiency Li-O2 battery using a LaNi-0.5Co0.5O3 perovskite cathode with extremely fast oxygen reduction and evolution kinetics(Elsevier Science, 2023-01-15) Qiu, Qianyuan; Pan, Zheng-Ze; Yao, Penghui; Yuan, Jiashu; Xia, Chun; Zhao, Yicheng; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; University of Waterloo; Tianjin UniversityRechargeable lithium-oxygen (Li-O2) batteries have been regarded as a promising energy storage device, but its practical use is impeded by its low energy efficiency. Herein, a bi-functional catalytic perovskite LaNi0.5Co0.5O3 (LNCO) is employed as the cathode of an efficient Li-O2 battery with a molten nitrate salt electrolyte at 160 °C. It displays a stable low charge–discharge overpotential 50 mV with a high energy efficiency (EE) 98.2 % at 0.1 mA cm−2 for over 100 cycles. The excellent performance is attributed to the extremely fast oxygen reduction and evolution kinetics on the surface of LNCO. The discharge product is Li2O with a porous and fluffy morphology which facilitates the transfer of oxygen and other intermediate species. It is noted that Li2O as a discharge product enables a theoretical specific energy density of 5200 Wh kg−1, which is superior to the Li2O2 as product giving 3500 Wh kg−1 for those ambient temperature Li-O2 batteries.Item A-site ordered double perovskite with in situ exsolved core-shell nanoparticles as anode for solid oxide fuel cells(AMERICAN CHEMICAL SOCIETY, 2019-02-20) Hou, Nianjun; Yao, Tongtong; Li, Ping; Yao, Xueli; Gan, Tian; Fan, Lijun; Wang, Jun; Zhi, Xiaojing; Zhao, Yicheng; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityA highly active anode material for solid oxide fuel cells resistant to carbon deposition is developed. Co-Fe co-doped La 0.5 Ba 0.5 MnO 3- with a cubic-hexagonal heterogeneous stucture is synthesized through the Pechini method. An A-site ordered double perovskite with Co 0.94 Fe 0.06 alloy-oxide core-shell nanoparticles on its surface is formed after reduction. The phase transition and the exsolution of the nanoparticles are investigated with X-ray diffraction, thermogravimetric analysis, and high-resolution transmission electron microscope. The exsolved nanoparticles with the layered double-perovskite supporter show a high catalytic activity. A single cell with that anode and a 300 μm thick La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 electrolyte layer exhibits maximum power densities of 1479 and 503 mW cm -2 at 850 °C with wet hydrogen and wet methane fuels, respectively. Moreover, the single cell fed with wet methane exhibits a stable power output at 850 °C for 200 h, demonstrating a high resistance to carbon deposition of the anode due to the strong anchor of the exsolved nanoparticles on the perovskite parent. The oxide shell also preserves the metal particles from coking.Item Achieve a high electrochemical oxidation activity by a self-assembled cermet composite anode with low Ni content for solid oxide fuel cells(Springer, 2023-10) Wu, Bingxue; Zhang, Jian; Yang, Zhi; Lu, Xuanlin; Zhao, Xin; Liu, Wen; Chen, Jiaxuan; Zhao, Yicheng; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityNi-based cermets are the most widely used anode materials for solid oxide fuel cells. Reducing the content of Ni is beneficial to anode stability but usually unfavorable for the catalytic activity. In this study, Ni-Ce0.8Sm0.2O2-δ anode with a low Ni content is synthesized through a polymer-directed evaporation-induced self-assembly strategy. Ni distributes evenly in the anode, resulting in an enlarged triple-phase boundary region and improved reactivity of lattice oxygen in the oxide phase. The anode containing 5 wt.% Ni possesses the highest amounts of oxygen vacancies and Ce3+/Ce4+ redox pairs that facilitates the charge transfer process, which is one of the rate-determining steps of anode reaction. Consequently, that anode shows the lowest polarization resistance of 0.014 Ω cm2 at 700 °C, much lower than those of other Ni-based anodes prepared through conventional techniques such as impregnation and solid-mixing. With that anode, a single cell supported by a 480-μm-thick Ce0.8Sm0.2O2-δ electrolyte layer exhibits the maximum power density of 270 mW cm−2 at 700 °C. The anode also shows a promising stability.Item Acid-Treated RuO2/Co3O4 Nanostructures for Acidic Oxygen Evolution Reaction Electrocatalysis(American Chemical Society, 2024-04-26) Huang, Xinhui; Lee, Carmen; Li, Yongdan; Xu, Junhua; Liu, Daobin; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Chinese Academy of Sciences; Nanyang Technological University; University of Science and Technology of ChinaRuO2 is widely used as an acidic electrocatalyst to achieve high catalytic activity, but the severe leaching and scarcity of the Ru element restrict application on a large scale. Strategies such as designing nanostructures and adjusting metals’ electronic properties to regulate the adsorption of reaction intermediates can be used for the design and preparation of catalysts. Herein, we designed an acid-treated RuO2/Co3O4 nanostructure electrocatalyst with low Ru content and an intimate heterogeneous interface to disrupt the trade-off relationship between stability and activity. The resulting acid-treated RuO2/Co3O4 displayed an overpotential of 152 mV in a 0.5 M H2SO4 electrolyte, greatly exceeding that of commercial RuO2 (221 mV). Despite continuous operation for 150 h, it still exhibited good stability with a degradation rate of 0.67 mV·h-1. Multiple characterization analyses revealed that an electron transfer occurs from Ruoct to Cooct(III) sites through the mutual O atoms in acid-treated RuO2/Co3O4, which is further strengthened by the presence of oxygen vacancies. The oxygen vacancy and heterogeneous interface synergistically regulate electronic dispersion, optimize the adsorption of the oxygen intermediates (*OOH), and improve the reaction kinetics of the oxygen evolution reaction (OER). This work brings to light the significance of oxygen vacancies for modulating the electronic structure of RuO2 nanoparticles and enhancing stability on Co3O4 support, thus highlighting the use of nanostructure and interfacial engineering to achieve better acidic OER catalyst design.Item An all organic redox flow battery with high cell voltage(ROYAL SOC CHEMISTRY, 2019-01-01) Huo, Yongjie; Xing, Xueqi; Zhang, Cuijuan; Wang, Xiang; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityAn all organic redox flow battery with 4,4′-dimethylbenzophenone (44DMBP) anolyte and 2,5-di-tert-butyl-1,4-dimethoxybenzene (DBB) catholyte shows a high open circuit voltage of 2.97 V, and average coulombic efficiency of 72% over 95 cycles at a current density of 1 mA cm -2 .Item Amorphous Co[sbnd]Mn binary oxides loaded on porous carbon nanosheet as bifunctional electrocatalysts for rechargeable zinc-air battery(Elsevier BV, 2023-08-15) Zhao, Linzhe; Li, Yongdan; Zhang, Cuijuan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityRechargeable zinc-air battery (RZAB) is very promising for large-scale energy storage whereas is impeded by the sluggish oxygen reduction/evolution reactions (ORR/OER). Developing high-performance yet cost-effective ORR/OER bifunctional catalysts is critical to accelerating its market penetration. Here, amorphous Co[sbnd]Mn binary oxides loaded on porous carbon nanosheets are prepared by a facile photochemical metal- organic deposition method. The evolution of composition, microstructure, ORR/OER performance with the calcination temperature is systematically investigated. The amorphous CoMn2Ox supported on carbon nanosheets shows higher ORR/OER bifunctional electrochemical performance in terms of activity and stability. The resultant RZAB with the amorphous CoMn2Ox on carbon nanosheets as air electrode delivers a peak power density of 89.6 mW cm−2 and maintains stable operation for ∼500 cycles at 10 mA cm−2. The ORR/OER bifunctional performance is closely associated with the microstructure, oxidation states of Co/Mn species and their corresponding proportions. Although there is great room to performance enhancement, this work sheds light on the development of high-performance and cheap ORR/OER bifunctional catalysts for rechargeable metal-air batteries by engineering the crystallinity of the metal oxides.Item Amorphous cobalt-cerium binary metal oxides as high performance electrocatalyst for oxygen evolution reaction(Academic Press Inc., 2020-04) Pan, Lili; Wang, Qingqing; Li, Yongdan; Zhang, Cuijuan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin University; State Key Laboratory of Chemical EngineeringThe amorphous Co-Ce binary metal oxides Co1-yCeyOx prepared by the photochemical metal–organic deposition (PMOD) method is developed as high performance electrocatalysts for oxygen evolution reaction (OER). The influence of Ce content on the OER activity is investigated in terms of geometric and electronic factors. Ce can remarkably enhance the OER activity of CoOx due to the synergistic effect of surface area, Co3+ content, and metal-OH bond strength when the content of Ce is less than 60%. Co0.9Ce0.1Ox supported on fluorine-doped tin oxide (FTO) coated glass substrate shows overpotential of 320 (2) mV at 10 mA cm−2 in 1 M KOH solution. The OER mechanism exploration reveals that the rate determining step changes with the Ce content due to the variation of metal-OH bond strength. This work sheds light on the design of high-performance yet cost-effective OER catalysts.Item Amorphous Nickel Oxides Supported on Carbon Nanosheets as High-Performance Catalysts for Electrochemical Synthesis of Hydrogen Peroxide(AMERICAN CHEMICAL SOCIETY, 2022-05-20) Wu, Zekun; Wang, Tianzuo; Zou, Ji Jun; Li, Yongdan; Zhang, Cuijuan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityThe development of high-performance yet cost-effective catalysts for electrochemical synthesis of H2O2 is a great challenge. Here, the amorphous nickel oxide NiOx supported on carbon nanosheets was prepared by the photochemical metal organic deposition method. The evolution of the crystalline structure, microstructure, and 2-electron oxygen reduction reaction (2e-ORR) activity in 0.1 M KOH was systematically investigated. The results reveal that the amorphous NiOx is highly efficient and selective toward 2e-ORR with an onset potential of 0.76 V versus reversible hydrogen electrode (RHE), 91% selectivity, and an electron transfer number of ∼2.2 over a wide potential range of 0.15-0.60 V versus RHE, which is outstanding among the metal oxide-based catalysts for 2e-ORR. Such a performance is closely associated with the mesoporous structure of the carbon nanosheets. Furthermore, the appropriate bonding strength of Ni-OH derived from the amorphous nature is crucial for the high selectivity. The theoretical calculation reveals that the *OOH intermediate prefers to adsorb on the amorphous NiOx-C by the end-on mode, facilitating the 2e-ORR process. The present amorphous NiOx loaded on carbon nanosheets can be promising electrocatalysts for synthesizing H2O2 after the stability issues are well addressed.Item Anthraquinone-based electroactive ionic species as stable multi-redox anode active materials for high-performance nonaqueous redox flow batteries(ROYAL SOC CHEMISTRY, 2021-10-14) Zhen, Yihan; Zhang, Cuijuan; Yuan, Jiashu; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityAnthraquinone (AQ)-based materials are promising active materials for aqueous redox flow batteries (ARFBs) owing to their fast kinetics and reversible two-electron redox reactions, but their application in non-aqueous RFBs (NARFBs) is limited by the low solubility and inferior stability of the charged species in aprotic solvents. Here, three AQ-based electroactive ionic species are purposely designed for NARFBs by incorporating the acetamide group and tetraalkylammonium ionic group into the anthraquinone structure and pairing with hydrophobic counter anions. Both experimental and theoretical calculation results show improved solubility and stability. A two-electron transfer redox flow battery with a mixed-reactant electrolyte delivers impressive cycling performance with an average coulombic efficiency of 96.8%, energy efficiency of 82.4%, and overall discharge capacity retention of 86.0% over 200 cycles (99.93% capacity retention per cycle) at 10 mA cm(-2). Furthermore, the battery exhibits robust rate capability to bear the current fluctuation.Item BaO-modified finger-like nickel-based anode for enhanced performance and durability of direct carbon solid oxide fuel cells(Elsevier BV, 2024-07-15) Li, Lin; Xie, Yujiao; Han, Tingting; Zhang, Jinjin; Yu, Fangyong; Li, Gen; Sunarso, Jaka; Yang, Naitao; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Shandong University of Technology; Swinburne University of TechnologyDirect carbon solid oxide fuel cells (DC-SOFCs) are hopeful high-temperature energy conversion devices with all-solid-state structure, high efficiency, and low emission. The anode catalytic activity is a direct limiting factor in the electrochemical performance of DC-SOFCs. Here, we successfully fabricated a finger-like Ni-based anode/electrolyte in one step, followed by infiltrating BaO within the anode, which significantly improved the anodic reaction and DC-SOFC performance. At 850 °C, the BaO/Ni-YSZ anode-supported DC-SOFC gave the optimal output of 505 and 825 mW cm−2 powering by activated carbon and hydrogen, respectively, which were significantly superior to those of the cell with traditional Ni-YSZ anode. Moreover, DC-SOFC with BaO/Ni-YSZ anode exhibited more stable operation for 20.9 h under 100 mA at 850 °C, giving a relatively high fuel utilization of 23.4 %. These excellent performances can be partially attributed to the smaller particle sizes and more grain boundaries of the BaO/Ni-YSZ anode due to the BaO infiltration, which effectively enhanced the ionic conductivity and mechanical strength of the anode. More importantly, density functional theory simulation revealed that the infiltrated BaO in the Ni-YSZ anode enhanced the adsorption ability of Ni sites for carbon monoxide and oxygen ions, which led to the increased differential charge densities and the reduction in the energy barrier of electrochemical oxidation reaction, thus effectively improving DC-SOFC performance and conversion efficiency.Item Base-free selective conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over a CoOx-CeO2 catalyst(ELSEVIER SCIENCE BV, 2021-05-01) Jin, Mengmeng; Yu, Linhao; Chen, Hong; Ma, Xueli; Cui, Kai; Wen, Zhe; Ma, Zewei; Sang, Yushuai; Chen, Mengmeng; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering TianjinCe oxide-based catalysts with different molar ratio of Co/Ce (denoted as CoCe-x, x represents the Co to Ce ratio) were examined as the catalyst of 5-hydroxymethylfurfural (5-HMF) oxidation to 2,5-furandicarboxylic acid (FDCA). The Co to Ce ratio, catalyst amount and reaction temperature all have remarkable effects on yield and selectivity. Complete conversion of 5-HMF with 86.3% selectivity of FDCA has been achieved over the CoCe-0.15 catalyst at 130 °C with 0.6 MPa O2 pressure (gauge) for 4 h. The good performance is attributed to the high specific surface area and the high oxygen vacancy concentration to promote the mobility and adsorption of oxygen species. In addition, the CoCe-0.15 catalyst is reused for five times without significant activity loss. Finally, the reaction mechanism over the CoCe-0.15 catalyst under base-free condition is discussed. 5-HMF is oxidized by the lattice oxygen via Mars-van Krevelen mechanism with the redox of Ce4+/Ce3+ and Co3+/Co2+, and the lattice oxygen is replenished by adsorbing and activating O2 molecules.Item Black TiO2-supported copper nanoparticles for efficient photocatalytic N-formylation of N-methylaniline with CO2(Elsevier BV, 2023-05) Yuan, Shibo; Bai, Peng; He, Yi; Chen, Jiafa; Zhao, Yicheng; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityPhotocatalytic N-formylation of amines with CO2 is a promising strategy to convert CO2 into value-added chemicals sustainably. In this work, a black TiO2-supported Cu photocatalyst is prepared through a solvothermal method for the N-formylation of N-methylaniline with NaBH4 as the reducing agent. Cu nanoparticles and oxygen vacancies are formed on the surface of the photocatalyst after reduction with H2, which decreases the band-gap energy and promotes the separation of photogenerated electrons and holes, thereby improving the photocatalytic activity remarkably. A 100 % conversion is achieved after 9 h radiation, and the yield of N-methylformanilide reaches 81 %. Both the amount of NaBH4 and the pressure of CO2 show important influences on the activity and selectivity of the photocatalytic process, and the carbon and hydrogen in the aldehyde group are from CO2 and NaBH4, respectively. The photocatalyst also shows promising cycling durability.Item Bulk phase charge transfer in focus – And in sequential along with surface steps(ELSEVIER SCIENCE BV, 2021-03-15) Pan, Zhengze; Li, Yongdan; Zhao, Yicheng; Zhang, Cuijuan; Chen, Hong; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityIn recent decades, catalysis has witnessed increasing interests in many catalytic reactions with bulk phase and interface charge transfer steps as a distinguished feature. Here, the charge can be cations, anions, electrons or holes. Research into both bulk phase and interface charge transfer has changed our understanding and in-focus design of catalysts and reactors, due to the clear difference in kinetics from those classical catalytic reactions, where only surface steps are concerned. This perspective selects several types of representative reactions and discusses the challenges and opportunities to innovations in catalytic technologies from the viewpoint of recognizing and accelerating the key step of the charge transfer at interface or in the catalyst bulk phase, as well as incorporating the surface steps into the overall kinetics.Item Catalysis and chemistry of lignin depolymerization in alcohol solvents - A review(ELSEVIER SCIENCE BV, 2023-01-15) Sang, Yushuai; Chen, Hong; Khalifeh, Mohamad; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityThe second-generation biofuel strategy aims to fully utilize lignocellulose, which is the major component of the plant cell wall and the most abundant form of renewable organic resources. Among three major components of lignocellulose, i.e. cellulose, hemicellulose and lignin, lignin has been the least utilized one up to now. Nevertheless, lignin depolymerization (LD) to produce aromatic chemicals and fuels has been intensely explored in the recent decade. Alcohols have been the mostly employed solvents in LD reaction, and are also involved into the LD reaction. This review provides an overview of the catalysis and chemistry of LD reaction in alcohols, especially in methanol, ethanol and isopropanol. The recent advances are firstly summarized, and then the roles of alcohol in LD reaction are outlined. The alcohol self-conversions are firstly discussed, and then the roles of alcohol are discussed in four subtopics: supplying hydrogen, depolymerizing lignin, hindering repolymerization and affecting monomer structure. Alcohol and alcohol-derived intermediates provide active hydrogen for reductive catalytic LD reaction carried out without hydrogen input, effectively break ether linkages but not C-C linkages in lignin, and also react with active intermediates and monomers, suppressing the repolymerization side reactions. In addition, alcohol also inhibits the hydrogenation of benzene rings and involves in the formation of products, affecting the structure of monomers. With these understandings, the challenges and opportunities of LD are proposed.Item Catalyst design for enzymatic hydrolysis lignin conversion into biofuels(2023-10-10) Agyingi, Cedric; Gong, Hanzhang; Yang, Mingze; Kemian tekniikan korkeakoulu; Li, YongdanEnzymatic hydrolysis lignin (EHL) obtained as a waste from the 2G-bioethanol process is currently underutilized by burning for energy. Its conversion to biofuels contributes to the drive towards sustainable fuels and improve the biorefinery economy. Studies on effective catalytic conversion of different types of lignin to biofuels are hampered by the complex nature of the lignin molecule and complexity on the sources of lignin. This thesis aims to design catalysts to completely transform EHL via direct catalytic solvolysis, using a fuel compatible solvent to biofuels. Two important reactions, hydrodeoxygenation (HDO) to remove O functionalities and C-C coupling alkylation are studied for EHL depolymerisation and product upgrade. Catalysts were prepared by impregnation and deposition methods, their activities tested and compared with some commercially obtained catalysts. Catalyst characterization was used to study the structures and functionalities of the prepared catalysts and propose catalyst active species. For HDO, highest total monomer yield of 16.6 wt% was obtained for the bimetallic Pd2.5IMNiDP/SiO2 catalyst. Catalyst characterization showed well dispersed nanosized metal particles for this catalyst. The metal particles are proposed as the active sites, dissociating molecular hydrogen to hydrogen radicals which break the C-O bonds. In the alkylation part, highest guaiacol conversion 99.6% and 2,6-ditertbutyl-4-ethylphenol yield of 54.8% were obtained with a 10%WO3/HY-500 catalyst. W5+ and W4+ were present in the used catalyst but not in the fresh catalyst which showed only W6+. W5+ is proposed as the active site, as W6+ is reduced in situ by hydrogen produced from alcohol conversion to olefin.Item Catalytic Conversion of Enzymatic Hydrolysis Lignin into Cycloalkanes over a Gamma-Alumina Supported Nickel Molybdenum Alloy Catalyst(ELSEVIER SCI LTD, 2021-03) Liu, Qingfeng; Bai, Yunfei; Chen, Hong; Chen, Mengmeng; Sang, Yushuai; Wu, Kai; Ma, Zewei; Ma, Yiming; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityThe efficient depolymerization and hydrodeoxygenation of enzymatic hydrolysis lignin are achieved in cyclohexane solvents over a gamma-alumina supported nickel molybdenum alloy catalyst in a single step. Under initial 3 MPa hydrogen at 320 °C, the highest overall cycloalkane yield of 104.4 mg/g enzymatic hydrolysis lignin with 44.4 wt% selectivity of ethyl-cyclohexane was obtained. The reaction atmosphere and temperature have significant effects on enzymatic hydrolysis lignin conversion, product type and distribution. The conversion of enzymatic hydrolysis lignin was also investigated over different nickel and molybdenum-based catalysts, and the gamma-alumina supported nickel molybdenum alloy catalyst exhibited the highest activity among those catalysts. To reveal the reaction pathways of alkylphenol hydrodeoxygenation, 4-ethylphenol was tested as a model compound. Complete conversion of 4-ethylphenol into cycloalkanes was achieved. A two-step mechanism of 4-ethylphenol dihydroxylation - hydrogenation is proposed, in which the benzene ring saturation is deemed as the rate-determining step.Item Catalytic conversion of Kraft lignin into platform chemicals in supercritical ethanol over a Mo(OCH2CH3)x/NaCl catalyst(ELSEVIER SCIENCE BV, 2023-01-15) Liu, Qingfeng; Sang, Yushuai; Bai, Yunfei; Wu, Kai; Ma, Zewei; Chen, Mengmeng; Ma, Yiming; Chen, Hong; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityA Mo(OCH2CH3)x/NaCl catalyst showed high efficiency in supercritical ethanol without adding H2 in the conversion of Kraft lignin to chemicals, including C6 alcohols, C8-C10 esters, benzyl alcohols and arenes. Control experiments were done with MoCl5, NaOC2H5 and the physical mixture of them. The Mo(OCH2CH3)x/NaCl catalyst exhibited superior activity among the samples examined. The overall yield increased as the reaction temperature increased from 260 to 300 °C. The yield of aromatic compounds achieved 303mg/g lignin over the Mo(OCH2CH3)x/NaCl catalyst at 300oC for 6h. MoCl5 and NaOC2H5 forms Mo(OCH2CH3)x in the catalyst preparation, which behaves as the active species in Kraft lignin conversion. The primary aromatics formed from the catalytic lignin depolymerization steps may undergo secondary reactions to form the final products.Item Catalytic depolymerization of a lignin-rich corncob residue into aromatics in supercritical ethanol over an alumina-supported nimo alloy catalyst(AMERICAN CHEMICAL SOCIETY, 2019-09-19) Bai, Yunfei; Cui, Kai; Sang, Yushuai; Wu, Kai; Yan, Fei; Mai, Fuhang; Ma, Zewei; Wen, Zhe; Chen, Hong; Chen, Mengmeng; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering TianjinA one-pot process for the depolymerization of lignin-rich corncob residue (LRCR) is investigated in supercritical ethanol over an alumina-supported NiMo (NiMo/Al) alloy catalyst. The LRCR, as a major byproduct in the corncob enzymatic hydrolysis process, was completely liquefied and effectively transformed into aromatic compounds without the formation of tar or char under optimal reaction conditions. The reaction temperature, time, solvent, and initial hydrogen pressure have significant effects on the depolymerization of LRCR. The highest overall aromatic yield of 255.4 mg/g of LRCR with 57.9 wt % alkylphenols (e.g., 4-ethylphenol, 2,5-diethylphenol, and 2,6-diisopropylphenol) was achieved with an initial 27.6 bar (gauge) of hydrogen in supercritical ethanol at 320 °C for 7.5 h. The depolymerization of LRCR is also examined over Ni/γ-Al2O3, Mo/γ-Al2O3, and the physical mixture of these two catalysts. The NiMo/Al alloy catalyst exhibits much higher activity than that of other catalysts, and a synergistic effect between Ni and Mo active species is proposed. Furthermore, X-ray powder diffraction results show that the Mo1.24Ni0.76 alloy is expected to be an important active species for the depolymerization reaction.Item Catalytic Ethanolysis of Enzymatic Hydrolysis Lignin over an Unsupported Nickel Catalyst : The Effect of Reaction Conditions(AMERICAN CHEMICAL SOCIETY, 2021-01-07) Sang, Yushuai; Wu, Kai; Liu, Qingfeng; Bai, Yunfei; Chen, Hong; Li, Yongdan; Tianjin University; Department of Chemical and Metallurgical EngineeringThe effect of reaction conditions on ethanolysis of enzymatic hydrolysis lignin (EHL) with an unsupported nickel catalyst, that is, Ni(220H), was investigated. The two-dimensional heteronuclear single quantum coherence-nuclear magnetic resonance (2D-HSQC NMR) analysis of liquid products revealed that both the ether and C-C linkages in EHL were cleaved during the reaction and the ether linkages were completely cleaved under mild reaction conditions, while the cleavage of C-C linkages needed harsh reaction conditions. At 280 °C under 2 MPa H2 within 6 h, the highest aromatic monomer yield of 28.5 wt % was achieved. Further increasing the reaction temperature to 300 °C or decreasing the initial hydrogen pressure to 0 MPa was conducive to the repolymerization reaction. The ortho-alkyl phenol monomers originated from the alkyl free radicals produced from ethanol. Under 0 MPa H2, the hydrogenation of -HCCH- in side chains was inefficient, and hence, the decarboxylation and alkenyl elimination reactions of side chains were favorable.Item Catalytic ethanolysis of microcrystalline cellulose over a sulfonated hydrothermal carbon catalyst(ELSEVIER SCIENCE BV, 2020-09-15) Wen, Zhe; Ma, Zewei; Mai, Fuhang; Yan, Fei; Yu, Linhao; Jin, Meng; Sang, Yushuai; Bai, Yunfei; Cui, Kai; Wu, Kai; Chen, Mengmeng; Chen, Hong; Li, Yongdan; Department of Chemical and Metallurgical Engineering; Industrial chemistry; Tianjin UniversityThe catalytic ethanolysis of microcrystalline cellulose in supercritical ethanol is examined over a sulfonated hydrothermal carbon catalyst (SHTC). SHTC is amorphous carbon containing −OH, −COOH and −SO3H groups with total acidity of 7.15 mmol/g and −SO3H acidity of 1.72 mmol/g. SHTC shows high catalytic activity towards the ethanolysis of cellulose in supercritical ethanol. Complete conversion of microcrystalline cellulose with high yields of ethyl levulinate and ethyl glucoside is obtained. The reaction temperature, time and catalyst amount have significant effects on the catalytic performances of SHTC. Appropriate reaction time and less catalyst amount are favorable for the production of ethyl glucoside, while prolonged reaction time and appropriate catalyst amount favor the production of ethyl levulinate. The highest yield of ethyl glucoside as 420.9 mg/g cellulose is obtained over 0.1 g SHTC at 245 ºC for 1 h. The highest yield of ethyl levulinate as 817.6 mg/g cellulose is achieved over 0.3 g SHTC at 245 ºC for 1 h. SHTC shows good stability in the recycle experiments with slight loss of catalytic activity.