ENERGY & FUELS
·
2024
·
IF 5.2
Xin Huang,Guangchuan Tang,Lei Tang,Chuan Ma,Yunlin Shao,Jingyu Ran
Bio-based platform chemicals are of great significance to future green fine and commodity chemicals. This study reports the performances and mechanisms of solvothermal dehydration of levoglucosan (LGA), the main precursor from noncatalytic pyrolysis of cellulose with a yield up to 80 wt %, to levoglucosenone (LGO) using cesium heteropolyacid salts at the catalyst in DMSO solvent. Catalyst characterizations revealed that cesium was well doped in the cubic of heteropolyacids, and the cesium doping ratio substantially influenced the catalytic performances toward LGO. LGO yield first increased and then decreased with the increase of cesium doping ratios, which is consistent with the change trends of pore structures and Brønsted/Lewis acid site ratios of the cesium heteropolyacid salts. LGO was obtained with the maximum yield at 41.2% over Cs2H2SiW12O40 compared to 39.2% over Cs2.5H0.5PW12O40. The catalyst can be regenerated by calcination without losing its catalytic performances. In addition, density functional theory calculation was used to reveal the mechanism for LGO formation, and the rate-determining step was the first step of the dehydration reaction with the energy barrier of 166 kJ/mol.
研究领域:
化学工程
·
可再生资源与环境科学
✓ 已验证
DOI
高影响因子
Journal of Biobased Materials and Bioenergy
·
2014
·Vol. 8
·期 4
·437-443
·
IF 0.586
Wang Wenju,Ren Junli,Li Huiling,Peng Feng,Sun Runcang,Liu Shijie
A feasible and environmental-friendly approach was developed for the dehydration of xylose into furfural using AlCl3-dominant catalysts in a homogeneous DMSO/H2O system. Results showed that the paired chlorides (AlCl3/KCl) in the molar fraction (χAlCl3
)
of 0.6 displayed the better catalytic performance than the single AlCl3 and the other paired chlorides. The influences of catalyst amount, reaction temperatures as well as xylose concentration on the dehydration of xylose into furfural were studied. The effects of co-solvents (DMF,
DMI, DMAC and NMP) on the production of furfural were also investigated. DMSO exhibited the better enhancement effect and the desirable DMSO/water volume ratio was 5:5, indicating DMSO could efficiently suppress the side reaction and enhance the selectivity. The maximum furfural yield of 43.6%
with xylose conversion of 97.9% and the selectivity of 44.6% was achieved at 170°C for 2 h with a total catalyst/xylose molar ratio of 0.5 at the solid to liquid ratio of 1:10.
研究领域:
化学工程
·
生物质转化
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2024
·
IF 3.7
Dechang Cheng,Zhihong Ma,Ziyang Liu,Xiaohui Liu,Tao Liu,Weizhen Sun,Ling Zhao
Isosorbide is a novel bio-based material, derived as a secondary dehydration product of sorbitol. This work focuses on the kinetics of sulfuric acid-catalyzed dehydration of sorbitol under conditions of non-constant volume. Herein, the effects of stirring rate, catalyst dosage, reaction temperature, and reaction time on the dehydration reaction of sorbitol were investigated. The yield of isosorbide up to 77.13% was obtained after 1.5 hours of reaction time under conditions of 2 kPa, 1.0% (mass) catalyst dosage, and 413.15 K. Based on the sorbitol dehydration reaction mechanism and a simplified reaction network, a kinetic model was developed in this work. A good agreement was accomplished between kinetic modeling and experiments between 393.15 and 423.15 K. The fitting results indicate that side reactions with higher activation energy are more affected by reaction temperatures, and the main side reaction that influences the selectivity of isosorbide is the oligomerization reaction among the primary dehydration products of sorbitol. The model fitting of the catalyst amounts effect shows that the effective concentration of sulfuric acid would be reduced with the increase of dosage due to the molecular agglomeration effect. Hopefully, the kinetic experiments and modeling results obtained in this work will be helpful to the design and optimization of the industrial sorbitol dehydration process.
研究领域:
化学工程
·
生物化工
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Meng Chen,Wei Lu,Hejun Zhu,Leifeng Gong,Ziang Zhao,Yunjie Ding
Linear α-olefins (C8–C12 α-olefin, LAOs) are acknowledged as high-value-added chemicals in both lubricant production and the polyolefin industry. An alternative route to the synthesis of high-purity LAOs is the dehydration of linear long-chain n-alcohols, whereas elevating the activity and selectivity of catalysts remains a challenge. Herein, we presented that on using sodium-modified γ-Al2O3 as the catalyst, a high selectivity (up to 96.87%) to 1-decene was achieved, and an optimized experimental condition (329 °C and 0.25 h–1) was found using the response surface method. Characterization results including X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), pyrolysis (Py)-IR, NH3-temperature-programmed desorption (TPD), and CO2-TPD showed that a suitable ratio (∼0.4 wt %) of sodium impregnation could inhibit the strong acid sites of the catalyst, and sodium impregnation led to the formation of additional base sites, which accounted for the synergistic effect with other acid sites to promote further conversion of ethers to olefins. This work is of significance for the synthesis of LAOs from long-chain n-alcohols.
研究领域:
催化化学
·
材料科学
·
石油化工
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2014
·
IF 2.235
Yuyuan Deng,Qin Zhang,Huachuan Zhang,Chengxi Zhang,Wenhu Wang,Yi Gu
To study oxazine ring formation in benzoxazine synthesis from phenol, primary amine and formaldehyde, reactions between 2-phenylaminomethylphenol (Mannich base) and formaldehyde in homogeneous dioxane/water solution are researched. Reaction orders, rate constants at different temperatures, and activation energy are calculated, the process of reaction is proposed, and the influence of acid and base is discussed. The reaction can occur at low temperature and generate the product 3,4-dihydro-2H-3-phenyl-1,3-benzoxazine. No intermediate 2-(N-hydroxymethyl-N-phenylamino)methylphenols are observed. The concentration of a Mannich base has little effect on the reaction rate, while the reaction is first-order to formaldehyde. Based on chemical properties of formaldehyde in aqueous solution, the reaction process includes the following three steps: degradation of poly(oxymethylene) glycols to methylene glycol, dehydration of methylene glycol to formaldehyde molecule, and the reaction between a Mannich base and formaldehyde molecule to benzoxazine. Dehydration of methylene glycols to formaldehyde molecules is the rate-controlling step.
研究领域:
有机化学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2014
·
IF 3.309
Huiling Li,Aojie Deng,Junli Ren,Changyu Liu,Wenju Wang,Feng Peng,Runcang Sun
One of the most promising strategies for furfural production is to extract continually the target product from the aqueous solution utilizing organic solvents. With the aim to develop an ecologically viable catalytic pathway for furfural production without the addition of mineral acids, we presented a modified biphasic system using a solid acid (SO 4 2− /TiO 2 -ZrO 2 /La 3+ ) as catalyst for producing furfural from xylose. Different kinds of aprotic organic solvents (DMSO, DMF and DMI) in water phase and 2-butanol in organic phase (MIBK) were investigated as reaction media. Furfural yield and xylose conversion efficiency were dependent on the amounts of aprotic organic solvents and 2-butanol, the solid/liquid ratio, and the volume ratio of the organic phase and the aqueous phase as well as the reaction temperature and time. As a result, DMI showed the best performance on improving furfural yield during the furfural production. 3563.3 μmol of furfural/g of xylose with 97.9% xylose conversion efficiency was obtained after 12 h at 180 °C when the volume ratios of water to DMI and MIBK to 2-butanol were 8:2 and 7:3, respectively.
研究领域:
生物化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
SYNTHETIC COMMUNICATIONS
·
2024
·
IF 1.8
Xiaoyun Ma,Xiaoyan Wan,Jun Zhao
A method for the preparation of nitriles from primary amides using trichloroacetonitrile and a catalytic amount of cupric acetate is described. Using this method, amides including aromatic amides, aromatic heterocyclic amides and aliphatic amides were converted into the corresponding nitriles in moderate to good yields. Trichloroacetonitrile reacted with amide in the presence of cupric acetate to form trichloroacetamide, which has been isolated and confirmed.
研究领域:
有机化学
·
合成化学
✓ 已验证
DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2015
·
IF 4.494
Zhiping Xu,Wenzhi Li,Zhijie Du,Hao Wu,Hasan Jameel,Hou-min Chang,Longlong Ma
A novel solid acid catalyst was prepared by the copolymerization of p-toluenesulfonic acid and paraformaldehyde and then characterized by FT-IR, TG/DTG, HRTEM and N 2 -BET. Furfural was successfully produced by the dehydration of xylose and xylan using the novel catalyst in γ-valerolactone. This investigation focused on effects of various reaction conditions including solvent, acid catalyst, reaction temperature, residence time, water concentration, xylose loading and catalyst dosage on the dehydration of xylose to furfural. It was found that the solid catalyst displayed extremely high activity for furfural production. 80.4% furfural yield with 98.8% xylose conversion was achieved at 170 °C for 10 min. The catalyst could be recycled at least five times without significant loss of activity. Furthermore, 83.5% furfural yield and 19.5% HMF yield were obtained from raw corn stalk under more severe conditions (190 °C for 100 min).
研究领域:
化学工程
·
生物质能
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Biomass Conversion and Biorefinery
·
2021
·Vol. 13
·期 9
·7895-7907
·
IF 4.987
Xia Qi,Peng Hong,Zhang Yu,Fu Guiming,Liu Yuhuan,Xiao Zhihong,Huang Lingling,Bi Haoran
Exploring environmental-friendly routine for efficient furfural production from lignocellulosic biomass is meaningful. Here, bamboo hemicellulose (BH) and xylose were used to produce furfural under microwave irradiation in a biphasic medium, in which 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO 4 ) served as the reaction phase and catalyst, whereas 1,4-dioxane served as the extraction phase. The effects of retention time, temperature, [Bmim]HSO 4 dosage, and water addition on the furfural yield were evaluated. Results showed the highest total furfural yields of xylose and BH could reach 55.65 mol% and 68.37 mol%, respectively, which were further enhanced to 63.87 mol% and 85.69 mol%, respectively, by adding a small amount of water. The kinetic analysis showed the dehydration rate constant of the formed xylose from BH to furfural was almost twice that of directly using xylose as substrate. Compared with the hydrolysis of BH to xylose, the dehydration of xylose to furfural required higher activation energy. The activation energy of consuming furfural to form by-products was higher than 73 kJ/mol. The recycled [Bmim]HSO 4 performed great reusability, and a small amount of ethanol residue could enhance the total furfural yields of xylose and BH, up to 73.48 mol% and 88.28 mol%, respectively.
研究领域:
生物化学
·
可再生资源工程
✓ 已验证
产品关联
DOI
高影响因子
CELLULOSE
·
2020
·Vol. 27
·期 17
·9825-9838
·
IF 4.21
Cao Qi,Ye Tian,Li Wenhui,Chen Jiao,Lu Yanyu,Gan Haifeng,Wu Hongli,Cao Fei,Wei Ping,Ouyang Pingkai
The dehydration of cellulose in polar aprotic solvents produces high-value anhydro-sugars, opening up a new avenue for the utilization of cellulose. However, there are still some problems that need to be solved. Herein, we selected some carbohydrates (e.g. cellulose, starch, cellobiose, maltose, methyl-β-D-glucopyranoside and methyl-α-D-glucopyranoside) to examine the influence of different glycosidic bonds and substituents on the preparation of levoglucosan (LGA). The results of LGA yields, reaction rate constants and activation energies from different saccharides show that β-glycosidic bond is more vulnerable to break, forming LGA more easily. The activation energies of the latter 4 carbohydrates are 89.9, 104.2, 93.3, 113.6 kJ/mol, respectively. The strength of acid affects the dehydration process of cellulose greatly. These acids whose p K a values are between − 3 and − 2, including p -toluenesulfonic acid, methanesulfonic acid, and sulfuric acid, can achieve the best yields of LGA and levoglucosenone (LGO). Accordingly, those acids with higher p K a value have no catalytic activity, whereas the rate of cellulose degradation using lower p K a valued acids as catalyst is too fast to be efficiently monitored and carbonization is severe. The side reaction of cellulose hydrolysis and the formation of byproducts including 5-hydroxymethylfurfural (HMF) and furfural (FF) could be suppressed effectively through the addition of phosphorus pentoxide as water absorbent into the reaction system. The molar concentration ratio of LGO and (HMF + FF + Glucose) reached 12.04, which is 105% higher than those without water absorbent. This ratio can reach 21.38 in LGA dehydration into LGO process when phosphorus pentoxide was added.
研究领域:
生物化学
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2015
·
IF 7.435
Jinxu Xi,Qineng Xia,Yi Shao,Daqian Ding,Panpan Yang,Xiaohui Liu,Guanzhong Lu,Yanqin Wang
Liquid bio-fuels derived from renewable biomass are of great importance on the potential substitution for the diminishing fossil fuels. Aqueous-phase process of sugar and sugar-derived molecules can be used to produce a range of alkanes and oxygenates. In this work, Pt/NbOPO 4 multifunctional catalyst was used in the alkane production by the hydrodeoxygenation of sorbitol in aqueous solution. The results indicated that Pt/NbOPO 4 catalyst showed the highest activity with 60% yield of C6 and C5 alkanes at 250 °C and 4 MPa H 2 among a series of catalysts. The reaction pathway showed that this process included dehydration, hydrogenolysis and CC bond cleavage. Isosorbide is the product of dehydration reaction and also an important intermediate in this process, which undergoes ring opening and following hydrogenolysis to form C6 hexane. The activation energy of sorbitol dehydration and isosorbide hydrogenolysis was calculated, that is 72.7 kJ/mol and 147.6 kJ/mol, respectively, over Pt/NbOPO 4 catalyst, much lower than those over Pt/ZrP and Pt/H-Beta catalysts, which would be attributed to the strong and high acid amount of NbOPO 4 as well as the promotion effect of NbO x for CO bond cleavage. The above results also showed that isosorbide hydrogenolysis is the rate-determine step. More importantly, Pt/NbOPO 4 catalyst was very stable, there was nearly no decrease of sorbitol conversion and no change of products distribution after working in a fixed bed reactor for 100 h. Therefore, Pt/NbOPO 4 is an efficient and stable catalyst for hexane production from sorbitol in aqueous media.
研究领域:
能源科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2014
·Vol. 32
·期 5
·434-442
·
IF 1.04
Changhua Song,Hui Liu,Yuan Li,Shuai Ge,Hongwei Wang,Wenshuai Zhu,Yonghui Chang,Changri Han,Huaming Li
A series of metal-Al 2 O 3 catalysts were prepared simply by the conventional impregnation with Al 2 O 3 and metal chlorides, which were applied to the dehydration of fructose to 5-hydroxymethylfurfural (HMF). An agreeable HMF yield of 93.1% was achieved from fructose at mild conditions (100°C and 40 min) when employing Cr(III)-Al 2 O 3 as catalyst in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The Cr(III)-Al 2 O 3 catalyst was characterized via XRD, DRS and Raman spectra and the results clarified the interaction between the Cr(III) and the alumina support. Meanwhile, the reaction solvents ([Bmim]Cl) collected after 1 st reaction run and 5 th reaction run were analyzed by ICP-OES and LC-ITMS and the results confirmed that no Cr(III) ion was dropped off from the alumina support during the fructose dehydration. Notably, Cr(III)-Al 2 O 3 catalyst had an excellent catalytic performance for glucose and sucrose and the HMF yields were reached to 73.7% and 84.1% at 120°C for 60 min, respectively. Furthermore, the system of Cr(III)-Al 2 O 3 and [Bmim]Cl exhibited a constant stability and activity at 100°C for 40 min and a favorable HMF yield was maintained after ten recycles.
研究领域:
化学工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）