PROCEEDINGS OF THE COMBUSTION INSTITUTE
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2016
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IF 4.12
Erwei Leng,Yang Wang,Xun Gong,Biao Zhang,Yang Zhang,Minghou Xu
The influence of KCl and CaCl 2 on the primary reactions of cellulose pyrolysis is studied using a wire-mesh reactor from 250 °C to 600 °C, focusing on the reaction intermediates. A pre- column derivatization with benzoyl chloride prior to HPLC analysis is applied for the quantification of anhydro-sugars (levoglucosan, cellobiosan, maltosan) from pyrolysis. At low temperatures, the additions of inorganics salts, especially CaCl 2 , weakens hydrogen bonds, resulting in high yields of levoglucosan and cellobiosan from the cleavage of glycosidic bonds rather than from dehydration reactions . At elevated temperatures, dehydration reactions in the sugar units are mainly responsible for the destruction of sugar rings followed by the scission of pyran rings, leading to the weight-loss of CaCl 2 -loaded cellulose in the form of low molecular weight organic species. Meanwhile, accumulated unsaturated structures suppress the cleavage of glycosidic bonds, leading to the formation of char. However, KCl appears to catalyze the cleavage of glycosidic bonds or the scission of pyran rings directly, which perhaps occurs through a homolytic mechanism, leading to low molecular weight species. Furthermore, maltosan is shown to be a secondary product and is catalyzed by KCl and CaCl 2 indirectly through the repolymerization of levoglucosan in the solid phase. A modified mechanism is also proposed regarding cellulose pyrolysis and the primary catalysis of KCl and CaCl 2 .
研究领域:
化学工程
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能源科学
✓ 已验证
DOI
高影响因子
COMBUSTION AND FLAME
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2019
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IF 4.12
Bin Hu,Qiang Lu,Zhen-Xi Zhang,Yu-Ting Wu,Kai Li,Chang-Qing Dong,Yong-Ping Yang
The fast pyrolysis mechanism of xylose , xylobiose and xylan was investigated with combined fast pyrolysis experiments and quantum chemistry calculations. The results indicate that acyclic d -xylose is an important intermediate for the formation of the major pyrolytic products in xylose pyrolysis, i.e., 1,4-anhydro- d -xylopyranose (ADX), furfural (FF) and hydroxyacetaldehyde (HAA). ADX derives from the successive cyclization of d -xylose which is the only source for ADX formation. 3-Deoxy-xylose is the most important intermediate for FF formation. HAA results from the C C bond scission by retro-aldol and cyclic Grob fragment. In addition, the five-membered intermediate derived from the ring-contraction reaction can transform into FF with high selectivity. The dehydrated xylose is also another source for HAA formation. The fast pyrolysis mechanism of xylobiose is similar to that of xylose, and thus similar pyrolytic product distribution can be obtained from them. However, the pyrolytic products of xylan differ significantly from those of xylose and xylobiose, which is ascribed to its high degree of polymerization and the branches in it.
研究领域:
化学工程
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生物质能
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2021
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IF 5.541
Jianjun Xiao,Minjiao Yang,Qingfeng Che,Yingquan Chen,Xu Chen,Haiping Yang,Pietro Bartocci,Francesco Fantozzi,Hanping Chen
The effect of potassium in biomass on the catalytic activity of ZSM-5 zeolite in the fast pyrolysis of biomass was investigated using 2-methylfuran (2-MF) as the typical model compound. The mechanism of action of potassium was explored in detail, along with the physicochemical properties of ZSM-5, including crystallinity, pore structure, and surface acidity. The physicochemical properties of ZSM-5 deteriorated to varying degrees after being tainted with different potassium sources (KOH, K 2 CO 3 , KAc, and KCl). Compared with neutral KCl and strong alkali KOH, K 2 CO 3 , and KAc, with weaker alkalinity but larger crystal structure, exerted a larger influence on ZSM-5. Changes in ZSM-5 tainted with K 2 CO 3 were the greatest, and crystallinity, surface area, acidity, and the corresponding yields of valuable aromatic hydrocarbons and gas products, all declined significantly, compared with raw ZSM-5. When the amount of K(CO 3 2− ) on ZSM-5 was less than 0.5 wt%, only minor (<10 %) changes were observed in crystallinity and surface area, but total acidity decreased by over 30 percent. The conversion of 2-MF was increased using ZSM-5 tainted with less than 0.5 wt% K(CO 3 2- ) and less liquid oxygenated compounds and more CO 2 were produced. Appropriate total acidity, adjusted by a tiny amount of K 2 CO 3 , could promote deoxygenation to CO 2. However, the decarbonylation reaction was inhibited, causing a negative effect on monocyclic aromatic hydrocarbons, which was attributed to the large-scale loss of both acidity and physical structure of ZSM-5 caused by more than 1.0 wt% K(CO 3 2- ).
研究领域:
化学工程
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
BIORESOURCE TECHNOLOGY
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2011
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IF 4.365
Xian-wei Sui,Zhi Wang,Bing Liao,Ying Zhang,Qing-xiang Guo
Fast pyrolysis of bagasse pretreated by sulfuric acid was conducted in a fixed bed reactor to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The liquid yield and LGO yield were studied at temperatures from 240 to 350 °C and sulfuric acid loadings from 0.92 to 7.10 wt.%. An optimal LGO yield of 7.58 wt.% was obtained at 270 °C with a sulfuric acid pretreatment concentration of 0.05 M (corresponding to 4.28 wt.% sulfuric acid loading). For comparison, microcrystalline cellulose pretreated by 0.05 M sulfuric acid solution was pyrolyzed at temperature from 270 °C to 320 °C, and bagasse loaded with 3–5 wt.% phosphoric acid was pyrolyzed at temperature from 270 °C to 350 °C. The highest yield of LGO from bagasse was 30% higher than that from microcrystalline cellulose, and treatment with sulfuric acid allowed a 21% higher yield than treatment with phosphoric acid.
研究领域:
生物化学工程
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可再生资源利用
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Energy Chemistry
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2019
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IF 5.162
Bin Hu,Qiang Lu,Yu-ting Wu,Wen-luan Xie,Min-shu Cui,Ji Liu,Chang-qing Dong,Yong-ping Yang
The catalytic fast pyrolysis of cellulose impregnated with phosphoric acid (H 3 PO 4 ) offers a promising method for the selective production of levoglucosenone (LGO), a valuable anhydrosugar product. However, the fundamental mechanism for selective LGO formation is unclear. Herein, quantum chemistry calculations and catalytic fast pyrolysis experiments were performed to reveal the formation mechanism of LGO in H 3 PO 4 -catalyzed cellulose pyrolysis. H 3 PO 4 significantly decreased the energy barriers of the pyrolytic reactions and altered the competitiveness of the LGO formation pathways, promoting LGO formation. Through different pathways in the non-catalytic and H 3 PO 4 -catalyzed conditions, LGO is mainly produced from the primary decomposition of glucose units of cellulose and secondary conversion of levoglucosan. The major catalytic formation pathways of LGO comprise similar reactions, with dehydration at the 3-OH + 2-H site as the rate-determining step. Importantly, secondary conversion of 1,4;3,6-dianhydro-α- d -glucopyranose is not feasible for LGO formation, in contrast to previous reports. In addition, a high degree of polymerization is beneficial for the selectivity of LGO formation in the catalytic process, because the glycosidic bond is important for the formation of the bicyclic structure (1,5- and 1,6-acetal rings).
研究领域:
化学工程
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生物质能
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量子化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
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2022
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IF 8.129
Anbang Xu,Xin Huang,Guangchuan Tang,Lei Tang,Changlei Qin,Zhongqing Yang,Jingyu Ran
Levoglucosenone (LGO) has shown a promising potential in the application of the sustainable chemistry. In this work, alkali metal-doped phosphotungstic acids, M 2.5 H 0.5 PW 12 O 40 (M = Li, Na, K, Rb and Cs), were synthesized and employed for catalytic fast pyrolysis of cellulose to selectively produce LGO. The results show that levoglucosan , the main precursor of LGO, was produced with a yield of 33.5 wt% by non-catalytic pyrolysis of cellulose, while LGO by catalytic fast pyrolysis of cellulose is mainly regulated by the strong/weak acid sites of the M 2.5 H 0.5 PW 12 O 40 . Increasing the atomic radius of the alkali metals from Li to Cs doping to phosphotungstic acid led to an increase of LGO yield, attaining to 15.6 wt% at 300 °C over Cs 2.5 H 0.5 PW 12 O 40 due to a high strong/weak acid site ratio. In addition, LGO yield was further enhanced to 19.2 wt% over (NH 4 ) 2 HPO 4 modified Cs 2.5 H 0.5 PW 12 O 40 as a result of an increase of moderate strong acid sites. This study provides a potential method for LGO production by catalytic pyrolysis of cellulose.
研究领域:
化学工程
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可再生资源利用
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
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2024
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IF 7.4
Zhaoying Li,Jinfu Lyu,Hao Qi,Daokuan Liang,Xiaofeng Li,Haoxi Ben,Lianghuan Wei,Qirong Yang
The large-scale blooming of Enteromorpha prolifera (EP) results in "green tide," triggering significant environmental issues . However, EP as algal biomass can be converted to syngas through fast pyrolysis . This research investigates the fast pyrolysis of modeled compounds of EP for syngas production . Rhamnose (Rha), glucuronic acid (GlcA), aspartic acid (Asp), glutamic acid (Glu), and alanine (Ala) are used as the model compounds. This study employs experiments and simulations on fast pyrolysis processes . The results reveal that polysaccharide sulfate (PS) undergoes various reactions, including glycosidic bond cleavage, pyran ring opening, dehydration, and C-C bond cleavage. Simultaneously, amino acids experience dehydration, deamination, decarboxylation , and decarboxylation reactions. Fast co-pyrolysis of modeled compounds of EP, the monosaccharides and uronic acid molecules produced by PS pyrolysis also attack each other with amino acid molecules to produce other substances. The pyrolysis gas obtained from the model compounds of PS exhibits the highest CO content. Notably, amino acids possess a superior capability to produce H 2 compared with PS. With the fast co-pyrolysis of EP model compounds, the CO 2 content increases while the CO content decreases. This study provides a theoretical basis for the fast pyrolysis of EP to produce syngas.
研究领域:
环境科学
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能源科学
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生物化学
✓ 已验证
DOI
高影响因子
FUEL
·
2020
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IF 5.578
Yuhan Yang,Hongyun Hu,Fu Yang,Hua Tang,Huan Liu,Baojun Yi,Xian Li,Hong Yao
This study, for the first time, investigated the volatiles emission and thermochemical conversion mechanism of bio-waste during pyrolysis in molten salts (NaNO 3 -KNO 3 -NaNO 2 ) at 300 °C. Cations of molten salts acted as catalysts while anions participated in the pyrolysis reaction. Compared with salt-free pyrolysis, more bio-waste was decomposed in molten salts, to produce more than 14 times the mass of gaseous products and twice the mass of liquid products. Furthermore, the thermochemical conversion behavior of typical biomass constituents, i.e. cellulose, hemicellulose and lignin, was also distinguished. The results suggested that lignin was most easily pyrolyzed to form numerous liquid acids, some nitrated aromatic compounds and more CO, H 2 . In contrast, the decomposition of cellulose was certainly restricted while more significant effects of anions were found in hemicellulose cracking by generating nitrogen-containing heterocyclic rings and amines. Besides, interactions among different biomass constituents were confirmed to affect the generation of bio-waste pyrolysis products.
研究领域:
能源与环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2022
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IF 5.876
Kongyan Yang,Feng Zhou,Huixia Ma,Chuntao Liu,Fangwei Ma,Guang Wu
A series of nanocrystalline ZSM-5 zeolites with abundant intercrystalline mesopores was fabricated by a hydrothermal crystallization method without any mesopore template. The ZSM-5 zeolite was characterized by XRD , XRF , N 2 adsorption, NMR, SEM, TEM and NH 3 -TPD and used for the catalytic fast pyrolysis (CFP) of cellulose . The external surface area of the nanocrystalline ZSM-5 zeolite reached 146.6 m 2 /g, larger than the external surface area of conventional ZSM-5 (57.9 m 2 /g). The product yields of the CFP reaction were studied over different Si/Al ratios of nanocrystalline ZSM-5, and the aromatic yield of nanocrystalline ZSM-5 was generally higher than the aromatic yield of conventional ZSM-5. The relationship between the surface area, acid amounts and product yields was established by drawing a linear fitting curve. The results show that both pore structure and acidity have important effects on aromatic yield and coke yield. Aromatics are generated in micropores, and the increase in external surface area caused by reducing the particle size improves the pyrolysis of cellulose to generate bio-oil vapours, which further diffuse into micropores to generate aromatics.
研究领域:
化学工程
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Bin Hu,Wen-luan Xie,Yu-ting Wu,Ji Liu,Shan-wei Ma,Ti-peng Wang,Shu Zheng,Qiang Lu
Furfural (FF) is a promising platform compound that can be selectively produced by the fast pyrolysis of xylan-based biomass in the presence of zinc chloride (ZnCl 2 ). Whereas, the catalytic effect of ZnCl 2 and the FF formation mechanism remain uncovered. The present work aims to give a deep insight into the formation mechanism of FF under the catalysis of ZnCl 2 by combining quantum chemistry calculations and fast pyrolysis experiments. Density functional theory (DFT) calculations and fast pyrolysis experiments were conducted with xylose as the model compound. ZnCl 2 affects the pyrolysis reactions through the binding of Zn atom and O atom of xylose initially, with manifest electron exchange between Zn and O. The activation free energies of the pyrolysis reactions can be decreased when ZnCl 2 stays at the reaction center of the transition states. Both ring-opening and 1,2-dehydration can be promoted by ZnCl 2 , whereas ring-contraction is hindered by ZnCl 2 because ZnCl 2 is away from the reaction center of the ring-contraction. Due to the distinct influence of ZnCl 2 on different reactions, the rate-determining steps in some of the possible FF formation pathways are changed. Hence, the competitiveness of these pathways is altered to a great degree, which should be responsible for the selective production of FF. Xylose tends to generate FF through the acyclic d -xylose decomposition channel due to the catalysis of ZnCl 2 . The most favorable FF generation pathway involves the successive cyclization, 1,2-dehydration between 2-OH and 1-H, electrocyclic dehydration, and 1,2-dehydration between 4-OH and 5-H following the formation of a d -xylulose intermediate.
研究领域:
化学工程
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催化反应机制
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2024
·
IF 5.6
Xin Su,Guosheng Li,Chao Fan,Tingting Zhou,Jing Liu,Beibei Yan,Yang Zhang,Guanyi Chen,Jingang Yao
Herein, the SAPO-31 produced phenol-rich bio-oil from Arundo donax (AD) via catalytic fast pyrolysis (CFP) in a fixed bed. Effective variables including type of catalyst, temperature, weight hourly space velocity (WHSV) and N 2 flow rate (Nfr) were evaluated to enhance the CFP. The results showed that SAPO-31 demonstrated selectivity of 80.28 % towards naphtha-range compounds and 33.57 % towards phenolic compounds (PCs) within the naphtha range at 500 °C, Nfr of 300 mL min −1 and WHSV of 1 h −1 , contrasting sharply with those of control groups (50.82 % and 14.40 %, respectively), HZSM-5 (67.66 % and 5.51 %, respectively) and Hβ (61.10 % and 25.50 %, respectively). Moreover, SAPO-31 gave the highest bio-oil yielded (26.97 wt%) compared to that of the control group (22.45 wt%), Hβ (22.21 wt%) and HZSM-5 (21.42 wt%). These results indicate that the SAPO-31 self-synthesized exhibits promising capabilities in producing phenol-rich naphtha-range compounds via the CFP of AD.
研究领域:
能源植物学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2024
·
IF 5.8
Ji Liu,Hao Fu,Bin Hu,Guan-zheng Zhou,Shou-gang Wei,Zhen-xi Zhang,Qiang Lu
Pyrolysis, a promising thermochemical conversion technique, can convert lignocellulosic biomass into various value-added products. Herein, the selective production of 1,4:3,6-dianhydro-α- d -glucopyranose (DGP) was achieved through fast pyrolysis of cellulose based on oxalic acid-assisted torrefaction (OAT) pretreatment. The mixture of cellulose and oxalic acid first underwent torrefaction, followed by fast pyrolysis to yield DGP. Simultaneously, the air atmosphere was considered to facilitate the formation of esterification intermediates, thereby promoting the formation of DGP. The effects of torrefaction temperature, oxalic acid amount, as well as pyrolysis temperature were carefully explored for DGP production. A yield of 9.6 wt% and a selectivity of 57.5 % for DGP were achieved from the micro-scale pyrolysis of cellulose under the optimized conditions. In lab-scale tests, the DGP yield reached 12.5 wt% from cellulose. The OAT-based pyrolysis was confirmed to be applicable to the waste cellulose-rich materials, with a DGP yield of 8.2 wt% from waste cotton and 6.0 wt% from spent paper in lab-scale experiments. Additionally, the OAT-based pyrolysis also showed the potential for poly-generation of DGP and formic acid at different stages.
研究领域:
能源与燃料化学
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生物质转化技术
✓ 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）