KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2016
·Vol. 33
·期 7
·2097-2106
·
IF 1.408
Bai Ting,Zhang Xin,Liu Xiling,Chen Tengfei,Fan Wentao
A series of HZSM-5 catalysts were synthesized by different methods. The physicochemical properties of the HZSM-5 catalysts were characterized by XRD, SEM, N2 isothermal adsorption-desorption, NH3-TPD, Py-IR and TGA, respectively. The results indicated that different preparation conditions lead to different morphologies, textures and the distribution of acid sites. The nanosized HZSM-5 catalysts exhibited better catalytic reactivity and coke capacity than the micro-sized HZSM-5 because nanosized HZSM-5 had larger specific surface area, higher pore volume, more exposed channels and more accessible acid sites. The large particles of NZ-3 in a reasonable range and the smooth surface were conducive to product diffusion; therefore, NZ-3 exhibited higher specific propylene yield and stability than the other nanosized catalysts. The moderate density and distribution of acid sites on NZ-3 also favored the formation of propylene.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
Nanomaterials
·
2025
·Vol. 15
·期 10
·751
·
IF 4.3
Jian Li,Laizhi Sun,Derun Hua,Xinning Lu,Dandan Yang,Zhiying Wu
Gallium-modified Zeolite Socony Mobil-5 (ZSM-5) zeolites were synthesized using wetness impregnation and hydrothermal synthesis methods. The structural and acidic properties of the zeolites were characterized through an analytical instrument, which demonstrated that Gallium-modified HZSM-5 zeolites retain the Mobil five instructure (MFI) framework structure, but exhibit a reduction in Brønsted acid sites and a decrease in micropore size. The catalytic performance of these zeolites in the pyrolysis of cellulose biomass and polyethylene was tested. Compared with HZSM-5, Ga-modified HZSM-5 zeolites considerably increased monoaromatic yields while reducing alkanes production. In particular, gallium-impregnated HZSM-5 increased the monoaromatic yield from 37.6% for ZSM-5 to 43.2%, while hydrothermal synthesized Ga-HMFI reduced polyaromatic and alkane yields from 6.6% and 24.6% for HZSM-5 to 2.9% and 11.4%, respectively. These results indicated that Ga-modified HZSM-5 zeolites can improve the synergy between cellulose-derived oxygenates and polyethylene-derived olefins, enhancing the yield of petrochemical hydrocarbons compared to that predicted by theoretical calculations.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Molecular Catalysis
·
2017
·
IF 0
Shuang Chu,Li’na Yang,Xingcui Guo,Linlin Dong,Xiufang Chen,Yaru Li,Xindong Mu
The catalytic behavior of a series of MFI catalysts with different Si/Al ratio (25–300) in the direct aqueous-phase hydrolysis of α-cellulose was studied. The effects ultrasonic pretreatment time, ZnCl 2 content, zeolite pore structure and acid-basic properties on catalyst activity and products distribution were systematically investigated. The results indicated that HZSM-5 with lower Si/Al ratio was beneficial for production of glucose and LA from α-cellulose. Ultrasonic pretreatment could decrease the degree of crystallinity and polymerization of α-cellulose, enhance the accessibility of acid sites and ZnCl 2 to the loosened amorphous regions of α-cellulose in water, and improve the hydrolysis efficiency of α-cellulose. The desilicated ZSM-5 (HZSM-5-DS(0.2)) showed much higher catalytic activities as compared to commercial ZSM-5 and α-cellulose conversion reached 76.5% over HZSM-5-DS(0.2) at 200 °C. Catalytic conversion of α-cellulose consisted of at least three important parallel reactions under the present hydrothermal conditions and a plausible pathway was proposed. Effective control of these reactions would be helpful to further maximize the target product yield during the catalytic conversion of α-cellulose.
研究领域:
化学工程
·
生物质转化
✓ 已验证
DOI
SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Boxuan Yang,Zheng Zhang,Chen Tian,Wenjing Yuan,Zhongqiu Hua,Shurui Fan,Yi Wu,Xuemin Tian
Gas sensors based on Pd-loaded SnO 2 were prepared with printed zeolite films on the top of the sensor layer to enhance selective response to methane. As expected, Pd-loaded SnO 2 has a sensitive response to CH 4 and VOCs, such as ethanol and acetone vapors. Pt catalyst was dispersed onto the surface to promote the catalytic activity of zeolite. According to the catalytic characterizations, it was indicated that interfered gases, CO and ethanol were catalytically oxidized into CO 2 and water vapor. Whereas the catalytic combustion of methane is a negligible and sensitive response to the interested analyte was significantly promoted. Thus, the selective response to CH 4 was greatly improved even in a mixture of CO and VOCs. Based on the power-law response to oxygen, it was found that the resistive responses of all sensors were highly oxygen-dependent, suggesting that oxygen adsorbates on the surface were involved in the sensing process and no difference with zeolite coated sensors. Thus, it can be concluded that zeolite films printed onto the sensing layer surface serve as a catalytic filter and responsible for the enhanced sensitive and selective response of methane.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2022
·
IF 3.656
Jiale Zhu,Siyan Yan,Guohao Xu,Xuedong Zhu,Fan Yang
A variety of HZSM-5 zeolites with different b-axis thicknesses and SiO 2 /Al 2 O 3 were fabricated by simply modifying urea content and Al source feeding in the initial gel, respectively. Multiple characterization technologies including XRD , SEM, N 2 adsorption-desorption, NH 3 -TPD and Py-IR were employed to investigate physicochemical properties of these samples and the possible crystallization mechanism was proposed that adsorption of urea molecules on (010) facet was the key factor for fabricating thin-sheet HZSM-5 zeolites. The results of hexane cracking reaction revealed that the selectivities of light olefins reached 46.5% when controlling b-axis thickness to 340 nm, exceeding the control sample by 12.2%. Furthermore, the effect of SiO 2 /Al 2 O 3 under this b-axis thickness was also investigated and concluded that keeping SiO 2 /Al 2 O 3 to 200 could exhibit the optimum catalytic performance with the conversion of 95.5% and light olefins selectivities of 56.7%. The reaction conditions were optimized to be 600 °C at the N 2 flow rate of 25 mL/min and WHSV of 3 h −1 to arouse the best performance. Under this condition, the distribution of ethene and propene was quite close to that of thermodynamic equilibrium. Based on these results, the primary and secondary products were uncovered, and further the reaction pathway of hexane cracking was disclosed. This new strategy to synthesize sheet-like catalysts for enhancing the catalytic properties in hexane cracking also laid a solid foundation for the study of the catalysts on light oil cracking in industry.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Yang Shen,Chunjiang Liu,Cunhao Cui,Hairong Ren,Mingming Gu,Haoran Liu,Zhongyue Zhou,Fei Qi
Lignin catalytic pyrolysis presents a promising and sustainable approach to producing aromatic molecules. Herein, we investigated the effect of modified zeolite with copper (Cu/HZSM-5) catalyst on efficiently pyrolyzed kraft lignin into aromatic hydrocarbons (AHs) production, especially mononuclear aromatic hydrocarbons (MAHs). Time-of-flight mass spectrometry (TOF-MS) was employed to compare the volatile product profiles of lignin during catalytic pyrolysis. The highest yield of MAHs reached 70.59 mg/g based on dry lignin at 550 °C, accounting for 70.23% among lignin pyrolysis products, compared to the pristine HZSM-5 zeolite catalytic system with MAHs yield of only 54.31 mg/g and of 40.34% in products. At 550 °C and 60 s residence time, the 5% Cu/HZSM-5 catalyst demonstrated the best performance compared to all other catalysts in terms of selectively producing MAHs. The results are ascribed to the enhancement of decarboxylation and aromatization processes by the doping of copper. This work demonstrates a cost-effective pathway that potentially converts kraft lignin into aromatic hydrocarbon production at a phenomenally high selectivity, providing a concept for industrial application toward biomass utilization and high value-added production.
研究领域:
生物质能
·
催化化学
·
可再生资源
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Jianfei Luo,Langlang Wang,Yibing Xie,Ping Ning,Yiran Xiong,Hang Zhang,Yixing Ma,Shao Zhang,Xueqian Wang
Existing processes for transforming arsine (AsH 3 ) into toxic arsenic oxides (As x O y ) through catalytic oxidation do not meet economic requirements. In contrast, the catalytic decomposition method stands out due to its ability to both remove AsH 3 and obtain elemental arsenic (As 0 ) as a valuable product. A series of blank molecular sieves (HZSM-5, 13X, MCM-41, and TS-1) was applied to the catalytic decomposition performance of AsH 3 . At a catalytic decomposition temperature of 100 ℃, the HZSM-5 zeolite exhibited exceptional performance, achieving a D 90% value (the duration for which the AsH 3 removal efficiency remained above 90 %) exceeding 40 h. Moreover, up to 83.1 % of the product was As 0 . Comprehensive characterization revealed that the surface of the HZSM-5 zeolite contained a large number of strong acid sites, which played a key role in As 0 generation. In situ diffuse reflectance infrared spectroscopy further revealed the activation behavior of O 2 at the Brønsted acid sites on HZSM-5. To assess its suitability in industrial applications, the AsH 3 removal performance of the HZSM-5 molecular sieve was investigated in the presence of actual gas components (CO, H 2 S, PH 3 ). This study provides new ideas for the effective catalytic decomposition of AsH 3 and the recovery of valuable products in industry.
CAS / MDL:
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Yingshu Liu,Haiyang Tao,Xiong Yang,Xiaoyong Wu,Jinjuan Li,Chuanzhao Zhang,Ralph T. Yang,Ziyi Li
Adsorption is a promising technology for capturing nitrogen oxides (NO x ) from humid flue gases , for which as the preferred NO x adsorbent, zeolite with an appropriate silica to alumina (Si/Al) ratio provides the key step for success in practical applications. In this work, the effects of Si/Al ratio, temperature, relative humidity (RH), and feed gas (NO x -H 2 O(g)–CO 2 –O 2 -N 2 ) compositions on NO x sorption behavior on HZSM-5 zeolites were systematically investigated, based on a series of characterizations, fixed-bed adsorption and temperature programmed desorption (TPD) tests. The low-silica HZSM-5(25) showed the best performance (326.6 μmol/g and 39.2 μmol/g at dry and 90%RH) as compared to others with higher Si/Al ratios at each RH, in which the roll-up effect was positively correlated with the Si/Al ratios and humidity. O 2 enhanced NO x adsorption and reached an optimal adsorption capacity at the concentration of 14%, while CO 2 had little effect on NO x adsorption. The decrease in temperature increased NO x adsorption capacity on HZSM-5(25), benefitting from NO 2 physisorption as well as satisfactory NO oxidation within the active adsorbent structure. The facile thermal desorption of NO x and significant NO–NO 2 conversion on HZSM-5(25) was exhibited by bimodal TPD peaks at 343–353K and 533–543K respective for NO and NO 2 , in contrast to those on Silicalite-1. A potential “water-resistant” strategy via the enhancement of NO x adsorption competitiveness was revealed, providing a theoretical guideline for NO x adsorbent screening in industrial applications.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2019
·
IF 3.774
Xiaohua Li,Wenbin Dong,Jin Zhang,Shanshan Shao,Yixi Cai
The Fe-, Co-, Cu-loaded HZSM-5 zeolites were prepared via impregnation method. The upgrading by catalyst on biomass pyrolysis vapors was conducted over modified zeolites to investigate their catalytic upgrading performance and anti-coking performance. The Brønsted acid sites amount on Cu-,Co-loaded HZSM-5 decreased sharply, while that of Lewis both increased. The yield of liquid fraction and refined bio-oil over metal loaded ZSM-5 catalysts decreased, while that of char almost kept constant. The physical property of refined bio-oil was promoted in terms of pH value, dynamic viscosity and higher heating value (HHV). FT-IR analysis revealed that the chemical structure of refined bio-oil obtained over Fe-, Co-, Cu-loaded HZSM-5 zeolites was highly similar. The yield of monocyclic aromatic and aliphatic hydrocarbon over Fe-,Co-loaded HZSM-5 were boosted by around 2.5 times compared with original ZSM-5 zeolites. Data analysis revealed that Cu/HZSM-5 presented the worst deoxygenation ability. The anti-coking capability of Fe/HZSM-5 was obviously better, i.e., the coke content showed an approximate decrease of 38%. Thus, this study provided an efficient Fe/HZSM-5 catalysts for preparation of bio-oil derived from catalytic upgrading of biomass pyrolysis vapor.
研究领域:
能源与燃料
·
催化化学
✓ 已验证
DOI
高影响因子
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
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2019
·Vol. 9
·期 15
·3933-3946
·
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.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2023
·
IF 16.5
Changcheng Wei,Wenna Zhang,Kuo Yang,Xiu Bai,Shutao Xu,Jinzhe Li,Zhongmin Liu
ABSTRACT The most promising method to eliminate CO 2 is to find large-scale and value-added applications of CO 2 as a carbon resource. However, the utilization of CO 2 as feedstock for basic chemicals has long been a great challenge owing to its high thermodynamic stability. Herein, we report the coupling conversion of CO 2 with light alkanes over the HZSM-5 zeolite with much higher aromatic selectivity than light alkanes as the only reactant. A CO 2 conversion of 17.5% and n -butane conversion of 100% with aromatic selectivity of 80% could be achieved by the coupling reaction at the CO 2 to n -butane ratio of 0.475, in which CO 2 not only acted as an agent for balancing hydrogen in the reaction but also partly (~25%) incorporated into the aromatic products. Methyl-substituted lactones (MLTOs) and methyl-substituted cycloalkenones (MCEOs) were identified as key intermediates during the coupling reaction. 13 C isotope labeling experiments, 13 C solid-state NMR, in-situ diffuse reflectance infrared Fourier transform spectroscopy, and density functional theory (DFT)calculations revealed that CO 2 could react with carbonium ions generated from alkane cracking to form MLTOs, which could further get converted into MCEOs, thus generating aromatic compounds . This coupling reaction provides guidance for the direct utilization of CO 2 to produce value-added chemicals with the simultaneous transformation of light alkanes.
研究领域:
化学工程
·
环境科学
·
材料科学
✓ 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）