INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Kezhen Qian,Wenmin Tian,Zixu Yang,Jing Xu,Huihua Pan,Lijie Yin,Dezhen Chen
The catalytic upcycling of end-of-life polyethylene by using hierarchical zeolites has garnered attention. Fine-tuning these zeolites’ micromesoporous structure and acidity is crucial for process efficiency, which requires a comprehensive understanding of their impact on polyethylene cracking. The impact of the mesoporosity and acidity of aggregated hierarchical HZSM-5 zeolites on high-density polyethylene (HDPE) vapor cracking was studied. The results indicated that the hierarchical structure enhanced accessibility to internal acid sites, facilitating monomolecular cracking and aromatization. Intercrystalline mesopores additionally heightened the alkylated aromatic yields. The Si/Al ratio shows a positive correlation toward the C5+ aliphatic hydrocarbon cracking, which boosts the formation of C2–C4 olefins and BTEX (benzene, toluene, ethylbenzene, and xylene). However, the presence of mesopores also yielded more heavy aromatics, thus increasing the risk of coking. The role of acid sites spatial distribution was investigated by poisoning the acid sites in micropores via pre-coking. The results indicated that the cracking of HDPE vapor occurred on the external acid of the zeolite, followed by the subsequent C5+ aliphatic hydrocarbon cracking on the mesopore and micropore to form aromatics and C1–C4 products. The formation of BTEX mainly occurred in the micropore, while the heavier aromatics and other alkylated benzenes were formed in the mesopore. The results of this study highlighted the importance of a proper hierarchical structure and acid site distribution in zeolites for effective and stable polyolefin cracking.
研究领域:
化学工程
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Yunwu Zheng,Jida Wang,Can Liu,Yi Lu,Xu Lin,Wenbin Li,Zhifeng Zheng
The main objective of the present work is to investigate the influence of nickel to cerium ratio on hydrogen exchanged Zeolite Socony Mobil-5 (HZSM-5) towards the catalytic upgrading of pine derived oxygenated pyrolysis vapours into aromatic hydrocarbon and phenol in pyrolysis oil via ex-situ fixed bed reactor . The presence of CeO 2 could change electron density of Ni, promote the reduction of Ni species, accelerate the transfer of carbon species, and suppress the production of carbon deposits (17.53%–25.11%) compared with the parent HZSM-5 catalyst (28.95%); it also improved the hydrodeoxygenation ability of all xNiyCe/HZSM-5(nickel and cerium bimetal modified HZSM-5) catalysts, resulting increases in noncondensable gas content (from 31.46% to 52.99%–65.53%). Ni to Ce ratio of 1:1 and 1:2 produced highest aromatic hydrocarbon (32.14%) and phenols (55.51%) relative peak areas. The acid center of HZSM-5 and the metal acid center of the Ni:Ce = 1:1 catalyst obviously fine-tuned the formation of coke; and promoted hydrocarbon production. Moreover, high Ni content promoted alkylation of benzene at C6–C9 and increased C10 + PAHs relative peak area; high Ce content promoted the formation of olefin and Increasing the cleavage of C–O bonds and promoted hydrogenation or dehydrogenation , reduced polycyclic aromatic hydrocarbons and coke yield, and increased phenols and alkylphenols selectivity.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
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2022
·
IF 11.072
Yibing Xie,Mengyu Wang,Xueqian Wang,Langlang Wang,Ping Ning,Yixing Ma,Jichang Lu,Rui Cao,Yu Xue
The traditional way for arsine (AsH 3 ) removal from the reducing exhaust gas by catalytic oxidation undershot the expect goal in pollutant emission control. This laboratory scale work used magnetic field to improve the chemical environment of AsH 3 catalytic oxidation over magnetic response catalyst Fe/HZSM-5. After introducing external magnetic field at a magnetic field intensity of 0.1 T, the catalytic performance of Fe/HZSM-5 for AsH 3 removal was improved by 52%, and the turnover frequency (TOF) value increased from 4.65 × 10 −3 s −1 to 5.73 × 10 −3 s −1 . The structure–activity relationship of the catalyst in the presence of magnetic field was investigated. The characterization results showed that Fe is mainly anchored onto the surface of Fe/HZSM-5 catalyst through an oxygen bridge, while a small proportion of Fe exists in the form of iron oxides . The Fe species and surface labile oxygen (O − ) in the aluminum tetrahedra are the magnetic active sites of Fe/HZSM-5, magnetic field promotes the reaction by increasing the activity of them. It was discovered that paramagnetic O − increased by 50% in the presence of magnetic field compared with that in its absence. Therefore, a magnetic-field-assisted oxygen cycling process is proposed. In terms of the stability of catalyst, formation of more amorphous oxidized arsenic after reaction in the presence of magnetic field reduced the toxicity to the strong acid sites of the catalyst, and the holding time of excellent AsH 3 removal efficiency was prolonged from 23 h to 35 h. These results provide new insights into magnetic-field-assisted zeolite catalysis.
研究领域:
环境科学
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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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2018
·
IF 3.468
Changsong Hu,Huiyan Zhang,Rui Xiao
In order to inhibit the coke formation on the external surface of HZSM-5 during catalytic fast pyrolysis (CFP) of biomass, core-shell structured HZSM-5@silicalite-1 zeolite catalysts were hydrothermally synthesized through the growth of silicalite-1 along the surface of a commercial HZSM-5. The catalyst characterization results indicate that silicalite-1 outer shell layer was successfully formed on the HZSM-5 core particles. Silicalite-1 coating was proved to be effective to reduce the external acidity as well as keep the internal acidity and channel patency of core HZSM-5 by catalytic probe reactions. The catalytic performances of HZSM-5@silicalite-1 samples in CFP of biomass were investigated using a bench-scale continuous feeding two-stage fluidized-bed/fixed-bed combination reactor. The results show that the productions of olefins and BTX were promoted (especially BTX), while the formations of catalyst coke and PAHs were significantly inhibited after silicalite-1 coating.
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
APPLIED CATALYSIS B-ENVIRONMENTAL
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2023
·
IF 22.1
Jieyi Liu,Junde Wei,Xiao Feng,Mingxia Song,Song Shi,Sibao Liu,Guozhu Liu
Hydrodeoxygenation (HDO) is one of the effective methods for upcycling polycarbonate (PC) plastic waste, but the development of low-cost, high-performance HDO catalysts still faces great challenges. In this work, we report that a bifunctional Ni/HZSM-5 catalyst can directly upgrade PC plastic wastes into sustainable aviation fuel ranged cycloalkanes in high yields (99.3 %) with 81.2 % yield of C 15 dicycloalkane under mild reaction conditions (190 °C, 4 MPa H 2 ). Controlled reactions of PC and probe molecules demonstrated the conversion of PC into C 15 dicycloalkanes involves PC depolymerization by direct cleavage of C-O bonds adjacent to benzene ring and ester group, forming C 15 aromatics and C 15 monophenols at the metal sites, followed by hydrogenation of C 15 aromatics rings on metallic Ni sites and HDO of C 15 monophenols on metal-acid dual sites parallel to generate C 15 dicycloalkane. The C-C cracking mainly occurred on the tertiary carbon adjacent to the benzene ring on acidic sites of HZSM-5, thus forming C 6 ∼C 9 monocyclic alkanes. The realization of this process can be attributed to the cooperation between metal sites and acid centers on Ni/HZSM-5. Besides, the metal-acid balance (MAB) in Ni/HZSM-5 significantly affected the HDO activity and product distribution. 20Ni/HZSM-5(200) with suitable MAB showed good HDO activity and excellent selectivity to C 15 dicycloalkane. In addition, the obtained catalyst was also capable of converting common real PC plastics wastes (CD disk, DVD disk and PC sheet) into cycloalkanes with the yield up to 98 % and exhibited excellent stability. This approach to construct inexpensive bifunctional catalysts highlights an efficient and reliable route for HDO of PC to sustainable aviation fuel, providing a new avenue towards a circular economy.
研究领域:
化学工程
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催化材料
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Jinsong Luo,Tianci Xiao,Wu Wen,Jun Bao,Chengyuan Liu,Yang Pan
The pursuit for higher light olefin selectivity and extended catalyst lifetime has been a hot topic in the methanol-to-olefins (MTO) process. The incorporation of Ca in HZSM-5 (Ca-modified HZSM-5) could exhibit outstanding catalytic stability and high C3+ olefins yield. In this work, synchrotron radiation photoionization mass spectrometry was applied to study the lifetime enhancement mechanism of Ca-modified HZSM-5. It is interesting to note that the mechanism differs in the cases of different Ca-loading. Under low Ca-loading, the main reason for lifetime enhancement is the modification of acid sites, which limited hydrogen transfer reactions and subsequent coking process. While higher Ca-loading would introduce CaO species over HZSM-5, which showed prominent activity for HCHO elimination. The decomposition of HCHO would suppress the HCHO-mediated aromatic formation pathway during the MTO process, therefore alleviating the coking process. Moreover, the elimination mechanism of HCHO over CaO was investigated using in situ IR measurements. This study provides some additional insights into the role of acid sites and CaO during the Ca-modified HZSM-5 catalyzed MTO process.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2016
·Vol. 19
·期 4
·2961-2973
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IF 4.449
Shiyou Xing,Pengmei Lv,Jiayan Wang,Junying Fu,Pei Fan,Lingmei Yang,Gaixiu Yang,Zhenhong Yuan,Yong Chen
For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8–25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6–C8 olefins over the catalysts' Brønsted acid sites; these underwent Diels–Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6–C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Brønsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
研究领域:
能源化学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Yiheng Wu,Yangping Lv,Ruipu Wang,Lixia Bao,Zhongdong Zhang,Dejun Shi,Anlv Zhang,Yaoyuan Zhang,Qi Liu,Qin Wu,Daxin Shi,Kangcheng Chen,Guiyuan Jiang,Hansheng Li
The aromatization of light alkane is an important process for increasing the aromatic production and utilization efficiency of light alkane resources simultaneously. Herein, Ga-modified HZSM-5 catalysts were prepared and investigated by a series of characterization techniques such as X-ray diffraction, nuclear magnetic resonance spectroscopy, transmission electron microscopy, N2 adsorption–desorption, and NH3 temperature-programmed desorption to study their physicochemical properties. The catalytic performance in propane aromatization was also tested. Importantly, the structure–activity relationship, reaction pathway, and coke formation mechanism in propane aromatization were systematically explored. It was found that different Ga introduction methods would affect the amounts of Brønsted and Lewis acid sites, and Ga-HZSM-5 prepared by the hydrothermal method exhibited higher amounts of Brønsted and Lewis acid sites but a lower B/L ratio. As a result, Ga-HZSM-5 showed higher propane conversion and benzene, toluene, and xylene yield compared with that of Ga2O3/HZSM-5. The propane aromatization reaction pathway indicated that propane dehydrogenation to propene was a crucial step for aromatic formation. The increase of the Lewis acid density in Ga-HZSM-5 can effectively improve the dehydrogenation rate and promote the aromatization reaction. Furthermore, the formation of coke species was studied by thermogravimetry–mass spectrometry and Raman approaches, the results of which indicated that the graphitization degree of coke formed over spent Ga-HZSM-5 is lower, resulting in enhanced anticoking stability.
研究领域:
催化
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化学工程
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材料科学
✓ 已验证
DOI
PubMed
高影响因子
BIORESOURCE TECHNOLOGY
·
2015
·
IF 4.494
Bo Zhang,Zhaoping Zhong,Paul Chen,Roger Ruan
Chemical vapor deposition with tetra-ethyl-orthosilicate as the modifier was applied to deposit the external acid sites of HZSM-5, and the modified HZSM-5 samples were used for the microwave-assisted catalytic fast pyrolysis (MACFP) of biomass for bio-oil production. The experimental results showed that the external acid sites of HZSM-5 decreased significantly when SiO 2 deposited amount increased from 0% to 5.9%. For product distribution, the coke yield decreased, the oil fraction yield decreased at first and then increased, and the yields of water and gas first increased and then decreased over the range of SiO 2 deposited amount studied. For chemical compositions in oil fraction, the relative contents of aliphatic hydrocarbons, aromatic hydrocarbons and oxygen-containing aromatic compounds first increased to maximum values and then decreased, while the relative content of oxygen-containing aliphatic compounds first decreased and then increased with increasing SiO 2 deposited amount.
研究领域:
能源与燃料化学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 106
·104398-104406
·
IF 3.289
Cong Zhang,Jingbo Qi,Jing Xing,Si-Fu Tang,Liang Song,Yuanyuan Sun,Chuanhui Zhang,Hongchuan Xin,Xuebing Li
Aqueous phase catalytic upgrading of lignin monomers to hydrocarbons via hydrodeoxygenation (HDO) has been explored using a combination of Pd/C and HZSM-5 catalysts under 2 MPa of H2 (ambient temperature). Model monomers with varying numbers of methoxy groups, including phenol, anisole, guaiacol and 2,6-dimethoxy-phenol, were chosen as lignin model compounds. Mechanistic studies revealed cascade and parallel reaction pathways via hydrogenation and dehydration (hydrolysis) processes, which were catalyzed by Pd/C and HZSM-5, respectively. Hydrogenation was preferred at lower temperature, whereas higher temperature was favorable for the removal of oxygen-containing functional groups. The effect of methoxy groups on the HDO of these monomers was also investigated systematically. Basically, the conversion of multi-substituted monomers was tougher than that of mono-substituted ones, due to steric constraint and the inhibition of the electron-donating hydroxyl group. The selectivities to cyclohexane from phenol and anisole were improved significantly by increasing the temperature to 413 K. However, cyclohexanone was preferably produced over cyclohexane when using model compounds with multi-substituents (guaiacol and 2,6-dimethoxy-phenol), even at temperatures above 513 K. Comparative experiments were also conducted on the HDO of 1,2-cyclohexanediol with or without the presence of phenol, which clearly suggested that the further HDO of guaiacol and 2,6-dimethoxy-phenol was inhibited, probably due to the strong interactions between cyclohexanediol molecules and Brønsted acid sites.
研究领域:
化学工程
·
催化反应
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2016
·
IF 4.509
Jie Su,Yue Liu,Weiyuan Yao,Zhongbiao Wu
In this paper, three kinds of HZSM-5-supported transition metal (Cr, Fe, and Cu) oxide catalysts were prepared by the wet impregnation method, and their stability performances for catalytic combustion of dichloromethane (DCM) were investigated. Different behaviors were observed for these three catalysts during a 300 min catalytic reaction running at 320 °C. It was found that the Cr–O/HZSM-5 catalyst showed good catalytic stability, while both Fe–O/HZSM-5 and Cu–O/HZSM-5 suffered obvious deactivation. Characterizations using XRD, BET, XPS, O2-TG, O2-TP-MS, NH3–IR, and temperature-programmed surface reaction (TPSR) techniques were then carried out to disclose the deactivation mechanisms. The results revealed that the main cause of the deactivation over the Fe–O/HZSM-5 catalyst was coke formation, which could be mainly attributed to its lower deep oxidation capacity of the intermediate products, i.e., the methoxy groups, and it could also be obtained that the Cu–O/HZSM-5 catalyst was severely poisoned by chlorine species owing to the formation of stable Cu(OH)Cl species. Based on the results above, it could be concluded that the close proximity and synergy between acidic sites and active oxygen species were crucial to avoid coke deposition during the chlorinated volatile organic compound catalytic oxidation process.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2024
·
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.
研究领域:
能源与环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）