Journal of Cleaner Production
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2024
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IF 9.7
Shanshan Shao,Yu Cao,Jiaxin Jiang,Xiaohua Li,Yongbo Yu
In this study, metal-loaded HZSM-5 was prepared with metal ion extracted from the cathode materials of spent lithium batteries (lithium iron phosphate, LFP; lithium nickel-cobalt manganate, NCM) with citric acid for the improved production of light aromatic hydrocarbons by catalytic pyrolysis of rape straw. Because of the dealuminization effect of citric acid on HZSM-5, mesopores were introduced, and the diffusion and conversion of pyrolysis gas over acid sites were improved. After metal loading with acid-leaching solution, the amount of weak and total acids in metal-loaded HZSM-5 increased a lot, which was conducive to the dehydration, deoxygenation, decarbonylation and aromatization of pyrolysis, and the production of monocyclic aromatic hydrocarbons (MAHs). With 0.1 mol/L citric acid for LFP and NCM treatment, the metal-loaded catalyst showed a higher yield of benzene, toluene and xylene (BTX) of 11.10 wt% during catalytic pyrolysis of rape straw. Compared with 0.1-NCM-H5, a higher yield of MAHs was obtained over 0.1-LFP-H5 with a more favorable pore structure and higher amounts of weak and total acid sites. In general, the high-valued utilization of agricultural wastes and spent lithium batteries was realized in this study to produce clean energy.
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高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2019
·
IF 3.774
Yunwu Zheng,Zhen Wang,Can Liu,Lei Tao,Yuanbo Huang,Zhifeng Zheng
By introducing exogenous nitrogen during biomass pyrolysis under nitrogen-rich conditions, high-value nitrogen-containing products, i.e., nitrogen-rich char and oil may be produced. Based on the cogeneration of high-value nitrogen products from biomass, biomass nitrogen-enriched pyrolysis was performed in a fixed bed with different sources and contents of ammonia. The yields, composition and characteristics of the products were investigated. Moreover, the formation mechanism of N-containing species was explored in depth for the pyrolysis and catalytic pyrolysis with HZSM-5 and Zn/HZSM-5 catalysts via elemental analysis, XPS, FTIR and BET. The results showed that ammonia impregnation could promote a Maillard reaction, reduce the content of small aldehydes and ketones, and produce a nitrogen-enriched bio-oil. The contents of N-containing species and phenolic substances in the pyrolysis oil of biomass impregnated with 10% urea reached 15.66% and 56.69%, respectively. Moreover, the nitrogen on the coke surface after pretreatment was mainly composed of C N, C N and N COO functional groups. The bio-char generated abundant pyridinic-N, pyrrolic-N, quaternary-N, and pyridone-N oxides. The presence of urea introduced many alkaline N-containing functional groups on the surface of the bio-char and promoted the transformation of nitrogen from amides and imides to heterocyclic nitrogen with higher thermal stability. Furthermore, Zn was an excellent catalyst for the Maillard reaction, and the Zn/HZSM-5 catalyst had a higher selectivity for aromatic hydrocarbons (96.98% for biomass and 86.48% for urea/biomass) and N-containing heterocyclic compounds, such as indoles (6.16% for biomass and 13.51% for urea/biomass). Additionally, the coke content decreased, and the catalyst deactivation decreased.
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高影响因子
APPLIED CATALYSIS A-GENERAL
·
2022
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IF 5.723
Yitao Zhao,Junjun Cheng,Peng Zhang,Xinhui Liu,Jianguo Zhuang,Yijun Yu,Qichao Zhao,Yuchen Wang,Xuedong Zhu,Fan Yang
Alkylation of benzene with carbon dioxide (CO 2 ) is significant for converting greenhouse gas and surplus benzene into value-added toluene and xylene. Herein, a bifunctional catalyst comprising Zn/Ga oxides and HZSM-5 zeolite was developed to efficiently promote the methylation of benzene with CO 2 and H 2 . This catalytic system exhibited excellent performance at 425 ℃ and 3.0 MPa, through which benzene conversion of 39.1% and total xylene/toluene selectivity of 92.7% have been achieved. Furthermore, the catalysts are carefully characterized; compositions of Zn/Ga oxides and Si/Al ratios of HZSM-5 zeolite are recognized as decisive factors for reaction activity and selectivity respectively. Additionally, primary reaction pathways are explored and testified to provide detailed understanding for the establishment of reaction networks, especially for mechanisms of ethylbenzene evolution. These findings are able to provide more deep insights into the process of benzene alkylation, which further facilitates the emergence of effective catalysts with potential industrial applications.
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高影响因子
BIOMASS & BIOENERGY
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2024
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IF 5.8
Zhenjing Jiang,Wuyu Wang,Xuelai Zhao,Xinghua Zhang,Qi Zhang,Longlong Ma
Production of jet fuel is not only promising but challenging in the field of biomass utilization. Here we proposed a novel route to produce highly branched alkanes with ultra-low freezing point using n-butyraldehyde as feedstock by self-aldol condensation and subsequent hydrodeoxygenation (HDO). The catalyst characterization revealed that the MgO-SiO 2 catalyst played an acid-base synergetic effect role in the self-aldol condensation of n-butyraldehyde using n-butanol as solvent, which obtained C8 oxygenate and C12 oxygenate with yield of 69.3 % and 26.8 % respectively. The medium Brønsted base site of the catalyst captured α-H to promote the formation of enolate from n-butyraldehyde, and the Lewis acid sites promoted the dehydration of intermediate products. DFT simulation showed that n-butanol activated α-C in enolate in aldol condensation, and deactivated the oxygen atoms in enolate by hydrogen bonds to inhibit side reactions. Finally, the obtained condensation products were subjected to HDO reaction over the 5 wt% Pd/C and HZSM-5 catalysts, obtaining the highly branched alkanes with an ultra-low freezing point of -120.7 °C for C8 alkane and -78.7 °C for C12 alkane suitable for bio-jet fuels.
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高影响因子
Catalysis Science & Technology
·
2019
·Vol. 9
·期 15
·3933-3946
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IF 5.726
Ting Wang,Yuebing Xu,Chengming Shi,Feng Jiang,Bing Liu,Xiaohao Liu
Direct conversion of syngas (CO/H2) into aromatics over tandem catalysts via the Fischer–Tropsch synthesis (FTS) route has attracted much attention because of its high one-pass conversion and milder reaction conditions. However, the complicated FTS product composition leads to more difficult mechanistic elucidation of aromatics formation compared to the methanol route. Herein, a series of strategies, such as covering external surface acid sites of HZSM-5 with a layer of inert SiO2, layered loading of an FeMn FTS catalyst and HZSM-5 zeolite in one reactor and two tandem reactors, and model reactions with ethylene and propylene over zeolite in a simulated FTS reaction environment, were applied to unveil the reaction mechanism and related factors affecting aromatic selectivity. It was found that different from the methanol route, the tandem FeMn–HZSM-5 catalyst produced aromatics mainly from the conversion of C5+ FT intermediates rather than light olefins (C2=–C4=). SiO2 coating could remarkably enhance the para-xylene (PX) selectivity due to hindering of its isomerization to major meta- and minor ortho-xylene (MX and OX) on the external surface acid sites of HZSM-5 by releasing the space confinement. The layered loading experiments in one reactor demonstrated that a farther distance from the FTS catalyst to zeolite largely increased the selectivity to BTX (benzene, toluene and xylene) in total aromatics from 48.3% to 68.9% on a carbon molar basis by suppressing the alkylation reaction of benzene and toluene with ethylene due to an obviously lower local ethylene concentration on HZSM-5. FeMn and HZSM-5 with layered loading in two tandem reactors confirmed that light olefins (C2=–C4=) were mainly hydrogenated and isomerized into paraffins. The model reactions with ethylene and propylene in a simulated local FTS reaction environment revealed that the presence of H2O and CO2in situ produced from the FTS reaction played a crucial role in promoting the aromatics formation at obviously lower reaction temperature which resulted from the enhancing acid strength and the driving H transfer to facilitate the cyclization and dehydrogenation reaction. This study provides a clear perspective for the aromatics formation mechanism and the tuning of the aromatic selectivity.
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高影响因子
FUEL
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2022
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IF 8.035
Ming Huang,Liang Zhu,Wenbiao Zhang,Lingjun Zhu,Zhongqing Ma,Dengyu Chen
Co-feeding of waste plastics during biomass catalytic fast pyrolysis can improve remarkably the yield of aromatic hydrocarbons. In this work, the simulated biomass by using its model components of cellulose, xylan, and lignin at different proportions was Co-CFP with LDPE to investigate the synergistic reaction mechanism between biomass and low-density polyethylene (LDPE) over hierarchical HZSM-5. Results showed that biomass and its model components were oxygen-enriched feedstock, while LDPE was the hydrogen-enriched feedstock with H/C eff over 2. The synergistic effect between biomass model components and LDPE was ordered as cellulose and LDPE > xylan and LDPE > lignin and LDPE. Because pyrolysis of cellulose produced higher yield of furans than that of xylan and lignin which acted as the key synergistic compounds in Diels-Alder reaction to form light aromatics. The transfer of hydrogen free radical from the LDPE-derived hydrocarbons to the biomass-derived oxygenates promoted the deoxygenation reaction of oxygenates in hierarchical HZSM-5. Diels-Alder reaction between furans and olefins was the key synergistic reaction which highly improved the yield of hydrocarbon aromatics. In general, the difference of the pyrolysis oxygenated intermediate among the biomass pseudo components resulted in different yields of light aromatics, where cellulose presented highest extent of synergistic reaction to LDPE.
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高影响因子
JOURNAL OF CATALYSIS
·
2026
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IF 6
Yufeng Yang,Shijing Zhang,Jiamei Ma,Jiating Shen,Jiajun Huang,Xianglan Xu,Xiuzhong Fang,Junwei Xu,Xiang Wang
Adopting effective methods to identify clearly the active surface sites is crucial to engineer high-performance catalysts. To develop cost-effective and applicable NH 3 -SCR catalysts, the distribution states of Ag on HZSM-5 support have been identified by XRD and XPS extrapolation methods. As quantified, Ag dispersion on HZSM-5 has a threshold of 0.12 mmol Ag/100 m 2 . Above the threshold, bigger Ag 0 particles with better capability to activate O 2 and NO x molecules can be formed, thus achieving Ag/ZSM-5 catalysts with much better reaction performance below 300 °C. In contrast, below the threshold, Ag is mainly present in the form of highly dispersed nano-clusters/micro-crystallites, and partly as Ag + ions, thus being unfavorable to the reaction at low temperature. DFT calculation has testified that the aggregated Ag 0 particles with bigger sizes (>5 nm) have weaker interfacial interaction with the support, thus showing better capability to activate the reactant molecules. The optimal NH 3 -SCR performance is achieved on 8% Ag/ZSM-5 with a mean Ag size of 8.6 nm and a Ag 0 /Ag + ratio of 1.72, on which 100% NO conversion with a wide window from 250 to 400 °C can be achieved with H 2 assistance. In conclusion, both the Ag particle size and Ag 0 /Ag + ratio are the two main factors determining NH 3 -SCR performance on Ag/ZSM-5 catalysts.
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高影响因子
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