FUEL
·
2020
·
IF 5.578
Bing Xu,Minghui Tan,Xuemei Wu,Hailun Geng,Faen Song,Qingxiang Ma,Chunhui Luan,Guohui Yang,Yisheng Tan
Dehydroaromatization of propane to high value-added aromatics, especially benzene, toluene and xylene (BTX), has attracted widespread attention. Many works have been done to improve the catalytic performance of gallium loaded HZSM-5 catalysts. However, there were few reports focused on reducing the cracked by-products, such as methane and ethylene, derived from propane cracking reaction on external Brønsted acidic sites of zeolite. Herein, chemical liquid deposition (CLD) method was adopted to passivate the external strong Brønsted acid of Ga/HZSM-5, aiming to increase the most value-added BTX production by suppressing the undesired propane cracking reaction. The content of deposited SiO 2 on the external surface of zeolite was tunable by varying the amount of liquid deposition reagent and duration time of CLD process. The results showed that an appropriate content of SiO 2 on external surface of catalyst was beneficial to disable the external strong Brønsted acid sites. Due to depressing the undesired propane cracking reaction, BTX selectivity of 55% with propane conversion of 49% was achieved on Ga/Z5-4Si catalyst, higher than those of Ga/HZSM-5. Otherwise, prolonging the duration time of CLD process narrowed the micropore mouth size of zeolite, which could enhance the shape selective effect of Ga/ZSM-5 to increase the proportion of para-xylene in total xylene products.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Zhongqiang Tang,Siyuan Zhao,Xiao Zhao,Runze Jin,Jiaofei Wang,Zhuangzhuang Zhang,Haobin Hu,Xinwen Guo,Chengyi Dai,Xiaoxun Ma
The conversion of naphthalene into high value-added intermediate, 2,6-dimethylnaphthalene (2,6-DMN), using methanol as an alkylating agent has been widely studied. However, the low conversion of naphthalene and the easy deactivation of catalysts due to carbon deposition still pose challenges for industrialization. This is attributed mainly to the huge difference in the conversion kinetics of naphthalene and methanol. Herein, we report the first one-step process for the synthesis of 2,6-DMN from naphthalene by direct alkylation with syngas over “ZnAlCrOx&HZSM-5″ bifunctional catalyst. Compared to the traditional alkylation process of naphthalene with methanol, the direct alkylation of naphthalene with syngas not only shortened the process route and improved the reaction balance of syngas to methanol, but also improved the effective utilization rate of CO (29.87 %), naphthalene conversion, and catalyst stability. Results indicated that the alkylation of naphthalene could be improved by appropriately narrowing the spacing between the ZnAlCrOx oxide and HZSM-5. The acid strength and acidity on the external surface of HZSM-5 were modified by P or Si to improve the initial conversion of naphthalene and the selectivity for 2,6-DMN. The difficulty in determining the deactivation point of catalysts with multiple active sites under complex catalytic systems was solved by adopting a strategy of ”improve shortcomings“. The decline of metal activity in this reaction was found to be the main reason for catalyst deactivation. Doping of Ce into ZnAlCrOx helped to improve the stability of the catalyst from 80 h to 120 h.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2019
·
IF 3.021
Zhen-Yi Du,Bin-Bin Zhang,Ting-Sheng Chen,Yuli Betancur,Wen-Ying Li
Isobutanol derived from biomass can serve as a potential renewable candidate for the production of light olefins and aromatics, which are the building blocks to manufacture fuels and chemicals in the petrochemical industry. Dependent upon the product requirements, the product selectivity toward olefins or aromatics can be tuned by adjusting the reaction conditions and the properties of HZSM-5 catalysts. On bare HZSM-5, mild conditions (low temperature, low space time, and low acidity) favored the production of olefins and harsh conditions (high temperature, high space time, and high acidity) were more likely to produce aromatics. Ga was impregnated onto HZSM-5 to enhance the production of aromatics. Unexpectedly, Ga introduction only induced the intertransformation between olefins and aromatics without significantly impacting the selectivity of low-value paraffins. The exchanged Ga sites functioning together with Brønsted acid were identified as active Ga species and strengthened the direct dehydrogenation of C6–C8 olefins. The in situ-generated water from isobutanol dehydration affected the formation of Ga species. This resulted in different promotional effects of Ga on the transformation of isobutanol and isobutene. The reaction pathways were developed on the basis of the catalyst evaluation results, in tandem with an in situ diffuse reflectance infrared Fourier transform spectroscopy study on the intermediates formed during isobutanol transformation. Selectivity of olefins and aromatics from isobutanol transformation can be tuned by adjusting reaction conditions and properties of HZSM-5 catalysts.
研究领域:
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS SURVEYS FROM ASIA
·
2018
·Vol. 22
·期 3
·129-135
·
IF 3.081
Zhang Di,Zhao Yun-Peng,Fan Xing,Liu Zhong-Qiu,Wang Rui-Yu,Wei Xian-Yong
A series of Ni/HZSM-5 catalysts with different Ni-loadings and Si/Al ratios were prepared by incipient wetness impregnation and employed for catalytic hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL). Their physicochemical properties were characterized by X-ray diffraction, nitrogen adsorption–desorption, X-ray photoelectron spectrometer, temperature-programmed desorption of ammonia,transmission electron microscopy, temperature-programmed reduction of hydrogen, and pyridine-adsorbed infrared spectroscopy. The diffraction peaks assigned to Ni phase were not observed, implying that nickel particles were small and had a high dispersion on the supports. The catalysts with a strong acidity and the appropriate ratio of Brönsted (B) acid sites to Lewis (L) acid sites (B/L = 4.9) show an excellent activity and selectivity for the hydrogenation of LA to GVL. High conversion of LA and selectivity towards GVL were achieved over 5 wt% Ni/HZSM-5-50. The maximum GVL yield of 100% over 5 wt% Ni/HZSM-5-50 was obtained under the optimized reaction conditions of 210 °C, 2 h, and 3 MPa initial hydrogen pressure.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED ORGANOMETALLIC CHEMISTRY
·
2019
·Vol. 33
·期 3
·e4745
·
IF 3.259
Yibing Xie,Langlang Wang,Ping Ning,Xueqian Wang,Qi Wang,Yingjie Zhang,Mengyu Wang
A series of Ce modified catalysts were prepared using equivalent-volumetric ultrasonic impregnation method for AsH 3 removal. The performance of catalytic oxidation of AsH 3 under dynamic conditions was studied under different synthesis and reaction conditions. Through screening tests, the optimum catalyst was impregnated by 10 wt.% Ce (CH 3 COO) 3 precursor and subsequently calcinated at 550 °C. When the reaction temperature reached 170 °C, the Ce-HZSM-5 catalyst could maintain an oxidation efficiency of over 90% in 82 hrs. Furthermore, the chemical structure and properties of the catalyst and its catalytic oxidation mechanism with AsH 3 were analyzed using SEM-EDS, BET, XRD, XPS, H 2 -TPR and FT-IR. The results showed that Ce mainly existed on the catalyst surface in the forms of Ce 4+ and Ce 3+ . In the reaction process, the chemisorbed oxygen played a key role in the transformation between the two valence states. AsH 3 was firstly oxidized to elemental As with the participation of lattice oxygen. Then, the elemental As was partially blown into the rear part of the adsorption column along with the air flow and subsequently, de-sublimed on the column wall. Herein, the elemental As remained on the surface of Ce-HZSM-5 catalyst, which would further oxidize to As 2 O 3 . For the recovery of As, Ce-HZSM-5 proved to be a promising catalyst in AsH 3 removal. Highlights The CeO x modified HZSM-5 catalyst was used to catalytic oxidation of AsH 3 . The Ce-HZSM-5 catalyst could maintain over 90% oxidation efficiency in 82 hrs. AsH 3 was catalytic oxidized to elemental As and H 2 O on the catalyst surface and the As can be collected. The As adsorbed on the catalyst surface can be oxidized to As 2 O 3 but cannot be further oxidized to As 2 O 5 .
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2016
·
IF 3.652
Jiajun Zhang,Beatriz Fidalgo,Dekui Shen,Rui Xiao,Sai Gu
This work investigated the decomposition of anisole (methoxyl-based lignin model compound) in a fluidized bed reactor over no catalysts and a series of HZSM-5 zeolite catalysts with different Si/Al atomic ratios. Transmethylation reaction was identified as the initial step of the thermal decomposition of anisole, leading to the prominent production of phenolic compounds. Methyl phenols were identified as the main products, with the yield of o -cresol being higher than that of p-cresol at the temperatures below 600° C. The transmethylation reaction over HZSM-5 zeolite catalyst was found to occur at temperatures 150° C lower than those for non-catalytic reaction, with the yield of the phenolic compounds being promoted by 2.5 times. Production of the main phenolic compounds during the catalytic decomposition of anisole was enhanced to different extents depending on the Si/Al ratio. The highest selectivity of 79 wt.% was achieved over the zeolite catalyst with a Si/Al ratio of 80. The Brønsted acid sites of the catalyst played a significant role in both the preferential formation of phenolic compounds and preservation of the methyl group.
研究领域:
催化化学
·
能源化学
✓ 已验证
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2023
·Vol. 17
·期 4
·404-414
·
IF 4.5
Cheng Junjun,Zhao Yitao,Xu Guohao,Zhang Peng,Zhu Xuedong,Yang Fan
Alkylation of benzene with carbon dioxide and hydrogen to produce toluene and xylene could increase the added-value of surplus benzene as well as relieve environmental problems like green-house effect. In this work, the alkylation benzene with carbon dioxide and hydrogen reaction was proceeded by using the mixture of zinc-zirconium oxide and HZSM-5 as bifunctional catalyst. The equivalent of Zn/Zr = 1 displays the best catalytic performance at 425 °C and 3.0 MPa, and benzene conversion reaches 42.9% with a selectivity of 90% towards toluene and xylene. Moreover, the carbon dioxide conversion achieves 23.3% and the carbon monoxide selectivity is lower than 35%, indicating that more than 50% carbon dioxide has been effectively incorporated into the target product, which is the best result as far as we know. Combined with characterizations, it indicated that the Zn and Zr formed a solid solution under specific conditions (Zn/Zr = 1). The as-formed solid solution not only possesses a high surface area but also provides a large amount of oxygen vacancies. Additionally, the bifunctional catalyst has excellent stabilities that could keep operating without deactivation for at least 80 h. This work provides promising industrial applications for the upgrading of aromatics.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Processes
·
2025
·Vol. 13
·期 5
·1440
·
IF 2.8
Tongtong Zhang,Sijia Wang,Xingyuan Li,Yupeng Du,Jiajun Hu,Shi Jiang,Yu Guo
Room-temperature complete oxidation of formaldehyde (HCHO) is an important orientation of research programs, yet challenges remain. The development of efficient catalysts with high activity and excellent stability is of great significance for such practical application. Inspired by this whole catalytic process, we, therefore, chose HZSM-5 zeolite with abundant acidic sites as catalyst support and lactic acid (LA) as modifier to regulate the properties. The use of LA simultaneously enhances the hydroxyls density and increases the dispersion of Pt nanoparticles, which are better than the reference catalyst prepared via direct wetness impregnation method. Most satisfying of all, the lactic acid-modified HZSM-5-supported Pt catalyst demonstrates a remarkable reaction performance for room-temperature HCHO oxidation at a high concentration HCHO of 80 ppm and a large space velocity of 360,000 mL/g/h (especially with a low Pt loading of 0.5%). In addition, a 120 h test further confirms the favorable stability of the designed catalyst. This pre-modified strategy using organic acid might provide potential approach in the construction of efficient zeolite-supported catalysts.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yan Wang,Kangqi Cao,Wenlong Sun,Xiangxi Lin,Jianwei Wang,Jessica Villarreal,Longzhi Li
Microwave catalytic pyrolysis of lignin is one of emerging technologies for efficiently converting lignin into fuels and chemicals. Molecular sieves (HZSM-5) are widely used as carriers to load metallic components for biomass pyrolysis but often encounter challenges such as high diffusion resistance and insufficient acidity of acidic sites. Traditionally, HZSM-5 is directly modified to enhance the activity of the acidic sites, but this modification is ineffective in improving the metallic components’ activity. Instead, we made nitrogen doping on Fe and then supported on HZSM-5 to construct Fe-N 25 /HZSM-5 catalysts for microwave catalytic pyrolysis of lignin. The N-doped Fe has the effect of “killing two birds with one stone” on enhancing the catalytic activity. The characterization results indicated that N replaced C of the graphitic carbon network to form carbon nitride structure, and further combined with Fe to generate Fe-N bonds, improving the electronegativity of the metallic component. Besides, the loading of N-doped Fe increased the acidity of the catalyst. The utilization of 1.00Fe-N 25 /HZSM-5 obtained the greatest bio-gas yield (35.2 wt%), a hydrogen yield of 27.8 mL/min, bio-oil yield (36.4 wt%) and phenol selectivity of 46.2 %. The likely pathway of microwave catalytic pyrolysis on Fe-N 25 /HZSM-5 was proposed through DFT calculation, using guaiacol as a model compound. The results suggested that N-doped Fe on HZSM-5 8 T tended to break the side-chain methoxy during pyrolysis of guaiacol, with energy barrier of 0.14 eV. This paper provides a promising strategy for modification of microwave pyrolysis catalysts.
研究领域:
能源化学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Hong Hai Wang,Zhi Ling Liu,Yu Cong Song,Hao Li
Hydrodeoxygenation (HDO) is one of the effective methods to upgrade biomass pyrolysis oil, but the development of a low-cost, high-performance HDO catalyst still faces enormous challenges. In this work, a facile and eco-friendly approach is developed to synthesize the Ni2P@hierarchical HZSM-5 catalyst. Structure and acidity of the catalyst can be controlled by simply adjusting the proportions of ammonia solution and the silicon to aluminum ratio, which are closely related to the performance of the catalyst. Experimental results reveal that the Ni2P@hierarchical HZSM-5 catalyst with Si/Al = 85 under NH3·H2O/Ni = 14 exhibits the highest activity of 98% guaiacol conversion, along with a 78.8% yield of cyclohexane (reaction conditions: 300 °C, 3 MPa H2). In addition, the guaiacol reaction network is provided.
研究领域:
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Jundong Xu,Yunfeng Guo,Tingting Huang,Yu Fan
This article proposes a novel decamethonium bromide-assisted method for modulating the size of supported metal nanoparticles in Pd/mesoporous HZSM-5 hydrodesulfurization (HDS) catalysts. The proposed approach significantly promotes the dispersion of supported palladium nanoparticles by bridging and anchoring the palladium precursor onto the surface of mesoporous HZSM-5 as well as restraining the subsequent aggregation of palladium nanoparticles in calcination. The as-prepared catalyst possessed higher 4,6-dimethyldibenzothiophene HDS activity than its counterpart that was prepared via impregnation due to its smaller Pd nanoparticles, higher Pd dispersion and higher content of Pd 0 species. This strategy provides a simple pathway for preparing supported metal nanoparticles with high dispersion.
研究领域:
催化化学
·
材料科学
·
能源化工
✓ 已验证
产品关联
DOI
高影响因子
ChemistrySelect
·
2024
·Vol. 9
·期 22
·e202401172
·
IF 1.9
Miao Mi,Jie Xiong,Suhong Zhang,Yidong Zhang,Xin Chen,Rong Shao,Wei Xu,Jianfei Ding
Graphical Compared to SnCl 2 and HZSM-5, SnCl 2 @HZSM-5 was a mesoporous composite, which had the most amount of total and weak acidity, and the weakest acid strength. More total acid content is beneficial to increase pentaerythritol conversion, and the weak acid can improve the selectivity of PETS, and weak acid strength is beneficial to inhibit the formation of carbon deposits. Therefore, SnCl 2 @HZSM-5 showed the highest pentaerythritol conversion, PETS selectivity and catalytic stability. The mesoporous HZSM-5 and SnCl 2 @HZSM-5 mesoporous composite were prepared by two-step crystallization and wet impregnation method, respectively. The catalytic esterification performances of SnCl 2 , HZSM-5 and SnCl 2 @HZSM-5 were compared. SnCl 2 @HZSM-5 had the most amount of total and weak acidity, and the weakest acid strength. More total acid content was beneficial to increase pentaerythritol conversion, and the weak acid could improve the selectivity of PETS, and weak acid strength was beneficial to inhibit the formation of carbon deposits. Brönsted and Lewis acid sites were present simultaneously on the SnCl 2 @HZSM-5 catalyst. Moreover, some extra Brönsted acid sites were created on the SnCl 2 @HZSM-5 catalyst, because the interaction of SnCl 2 with HZSM-5 may result in the exchange of Sn 2+ with protons. Both acid sites could catalyze the esterification reaction, and the Brönsted acid site was more beneficial to increasing PETS selectivity. Therefore, SnCl 2 @HZSM-5 showed the highest pentaerythritol conversion, PETS selectivity and catalytic stability. The generation of coke and the leaching of Sn were the main cause of catalyst deactivation. Under the optimized process conditions: 105 °C, 4.7 molar ratio of stearic acid and pentaerythritol, 1.2 wt % catalyst amount and 2.5 wt % SnCl 2 loading, after 3 h reaction time, the pentaerythritol conversion, PETS selectivity and yield was 99.3 %, 97.2 % and 96.5 %, respectively.
研究领域:
化学工程
·
催化科学
✓ 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）