Catalysts
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2017
·Vol. 7
·期 1
·21
·
IF 3.082
Yang Han,Bo Wen,Mingyuan Zhu
In this study, we prepared core-shell structured Ni@SiO2catalysts using chemical precipitation and modified Stöber methods. The obtained Ni@SiO2samples exhibited excellent catalysis performances, including high CO conversion of 99.0% and CH4yield of 89.8%. Moreover, Ni@SiO2exhibited excellent catalytic stability during a 100 h lifetime test, which was superior to that of the Ni/SiO2catalyst. The prepared samples were characterized using a series of techniques, and the results indicated that the catalytic performance for syngas methanation reaction of the Ni@SiO2sample was markedly improved owing to its nanoreactor structure. The strong interaction between the Ni core and the SiO2shell effectively restrained the growth of particles, and the deposition of C species.Keywords:syngas methanation;Ni@SiO2;anti-carbon deposition;catalytic stability
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2022
·
IF 4.889
He Han,Anfeng Zhang,Limin Ren,Xiaowa Nie,Min Liu,Yi Liu,Chuan Shi,Hong Yang,Chunshan Song,Xinwen Guo
Shape-selective alkylation of toluene with methanol is one of the most attractive promising synthetic routes to para -xylene. To date, modified ZSM-5 zeolites are considered to be one of the best candidate catalysts for this reaction. Although the para -selectivity could be tuned to approaching 100% by modification of the zeolite and optimization of reaction conditions, at present, there is still a lack of effective means to inhibit the rapid deactivation of the catalysts due to coke formation. In this work, a coke-resistant (Pt + Ni)/ZSM-5 zeolite with excellent stability for shape-selective alkylation of toluene with methanol to para -xylene is developed. The pore structure and acid properties of the zeolite are effectively tuned to ensure high para -selectivity. Meanwhile, the co-existence of Pt and Ni species in this catalyst plays the critical role in inhibiting coke formation, as the two species concurrently impede the formation of olefins, the main coking precursors, via two distinctive mechanisms.
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
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Kai Shi,Yang Deng,Xia An,Xu Wu,Xianmei Xie
This work focused on optimizing the synergistic effect between CeO 2 and Ni in CeO 2 modified Ni/MgAl 2 O 4 . Six catalysts for ethanol steam reforming (ESR), including NiCeMgAl, CeO 2 /NiMgAl, Ni/CeMgAl, Ni-CeO 2 /MgAl 2 O 4 , Ni/CeO 2 /MgAl 2 O 4 and CeO 2 /Ni/MgAl 2 O 4 , were synthesized by sol–gel and/or impregnation methods, which controlled the introduction order of Ce(NO 3 ) 3 . Ni/CeMgAl showed a satisfactory stability with 90.6 % of ethanol conversion after 100 h test, 66.9 % of H 2 concentration in product, and an excellent anti-coking ability with 0.72 mg c /(g cat ·h). The optimal catalytic performance of Ni/CeMgAl benefits from the unique distribution of components, which provides adequate Ni 0 active sites for C-C bonds scission, maintains a stable particle size of metallic Ni, and suppresses the side reactions and carbonization of intermediates on CeO 2 sites. This work illuminates the important of coordinating the ability of Ni and CeO 2 for ESR and presents a new insight into the design of low-cost and high-performance catalysts in practical applications.
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
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Kai Shi,Yin Che,Yang Deng,Xia An,Xianmei Xie,Xu Wu
Bimetallic catalysts with unique geometric and electronic structure exhibit high performance compared to that of monometallic counterparts in the ethanol steam reforming (ESR). Herein, NiCo bimetals supported on CeO 2 doped MgAl 2 O 4 (NiCo/CeMgAl) with different ratio of Ni/Co were prepared for ESR. The synergies between Ni and Co in catalytic activities and ability to anti-coking were focused. The results demonstrate Co atoms trend to segregate toward the surface and are oxidized synchronously, forming the Ni-CoO hybrid surface. The reduced Ni particles are beneficial to maintain a stable catalytic activity for the C-C bonds scission, and the CoO particles formed by segregation and irreversible oxidation of Co 0 are more conducive to activation of H 2 O, the resulting OH promotes the transformation of CH x species, which significantly reduces the selectivity of CH 4 and prevents the formation of filamentous carbon. Controlling Co content and maintaining a stable M/M δ+ are critical to balance the C-C bond scission reaction and the CH 3 * conversion reaction on the NiCo bimetallic catalysts. The optimal catalyst 9Ni1Co/CeMgAl shows the ethanol conversion of 93.9 % at TOS of 100 h, and the average rate of coke formation is 0.50 mg c ·g cat -1 ·h −1 .
研究领域:
化学工程
·
催化
✓ 已验证
产品关联
DOI
高影响因子
Advanced Sustainable Systems
·
2020
·Vol. 4
·期 9
·2000092
·
IF 4.869
Zhe Wang,Yuzhuo Chen,Shanjun Mao,Kejun Wu,Kaichao Zhang,Qichuan Li,Yong Wang
Propane dehydrogenation (PDH) catalyzed by PtSn/Al 2 O 3 is a vital industrial process for producing propylene, a significant building block in the chemical industry. However, coke produced in the process deactivates the catalyst and the energy-intensive regeneration procedures can produce considerable CO 2 emission. In this work, coke on the spent catalysts is analyzed by thermogravimetric-mass spectra, Raman spectra, 1 H solid NMR spectra, and infrared spectra. Several C 3 species, including propyl, propylidene and propylidyne are found on the surface of the PtSn alloy. Several reaction pathways are investigated by density functional theory (DFT) calculations. It is also found that this coke can be hydrogenated to propylene in the PDH process. These results could provide theoretical guidance for optimizing process parameters in industry.
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
CATALYSIS LETTERS
·
2021
·Vol. 152
·期 5
·1372-1385
·
IF 3.186
Qiu Baocheng,Zhang Yakun,Zhang Yi
The rapid deactivation caused by coke deposits is the major obstacle to the ethane aromatization of Zn-based catalysts. We have successfully synthesized a Zn-embedded inside HZSM-5 crystal catalyst (Zn@HZSM-5) by hydrothermal synthesis using preformed Zn/SiO 2 as the only silicone source. Based on various characterization results, including in situ etching XPS, operando DRIFTS, as well as NMR, it is found that Zn(OH) + and [Zn–O–Zn] 2+ species are active sites for ethane aromatization for zinc-based catalysts, and their dynamic transformation significantly changes reaction performance of ethane dehydrogenation. For the Zn/HZSM-5 catalyst, the existence of a large number of [Zn–O–Zn] 2+ species causes higher initial ethane conversion and higher selectivity of aromatics, resulting in a large amount of coke deposits. Moreover, [Zn–O–Zn] 2+ species on the Zn/HZSM-5 catalyst fast transit to Zn(OH) + species and subsequently form the sintered ZnO species, leading to rapid deactivation. For the Zn@HZSM-5 catalyst, the embedded structure contributes to forming more Zn(OH) + species and delays the transformation of the Zn(OH) + species to [Zn–O–Zn] 2+ species, resulting in slowly increased selectivity of aromatics during the reaction. Therefore, the Zn@HZSM-5 catalyst realizes stable ethane conversion with dynamic selectivity. Graphic Abstract
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 PROCESSING TECHNOLOGY
·
2019
·
IF 4.507
Huiying Wang,Zhenning Yang,Jie Liu,Guozhu Li,Xiangwen Zhang
Coking during endothermic hydrocarbon fuel cracking is a key problem that has to be considered. In this study, anti-coking effect was systematically studied by using water, ethanol and HPW as additives on the coatings of CsOH and BaCeO 3 during RP-3 cracking. The morphology, type and amount of coke deposits on the coatings were characterized by means of scanning electron microscopy (SEM), temperature programmed oxidation (TPO) and quantitative carbonization method, respectively. The results show that either the additive or the catalytic coating can effectively remove the coke deposits on the reaction tube. Remarkably, BaCeO 3 coating is more effective in inhibiting the formation of fiber coke compared with CsOH coating，which is conducive to the cracking reaction. The best anti-coking effect is achieved by using 5 wt% ethanol as additive on the BaCeO 3 /HPW coating, and the inhibiting percentage is 97%. In addition, a possible anti-coking mechanism of carbon-steam gasification through BaCeO 3 /HPW coating and ethanol has been proposed.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Li Zhang,Yue Hu,Weibin Xu,Chuande Huang,Yang Su,Ming Tian,Yanyan Zhu,Huimin Gong,Xiaodong Wang
Iron-based oxides are promising oxygen carriers for chemical looping syngas production from methane; however, facile coke formation over reduced metallic Fe0 largely limits the syngas productivity. This work demonstrates that the introduction of Sn promoters into BaFe1–xSnxO3−δ perovskite oxides significantly restrains coke formation and improves the syngas yield to above 19.2 mmol/g with a H2/CO ratio of 2, which is 2.9-fold in comparison to BaFeO3−δ. Characterization results suggest that Sn cations are well-confined in the perovskite matrix by substitution of Fe. The Fe cations serve as main active sites for C–H bond activation with Sn cations as an oxygen reservoir, which donate the neighboring lattice oxygen to active Fe for selective methane oxidation. Besides, an intimate Fe–Sn interaction induces the formation of the FeSn alloy rather than metallic Fe0 under a reducing atmosphere, which restrains methane pyrolysis and notably improves the coke resistance. When Sn loading (x) increases to above 0.6, all Fe cations can be deeply reduced to the metallic state without coke accumulation and oxygen storage capacity reaches as high as ca. 6.5 mmol/g with nearly 100% syngas selectivity, which breaks the “seesaw” effect between oxygen supply and syngas selectivity for traditional iron-based materials. These results provide meaningful guidance for fabricating prospective oxygen carriers or catalysts with better anti-coke property for the chemical looping process or specific catalytic reactions.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2021
·
IF 5.062
Freeman Bwalya Kabwe,Jian Qiang Zhong,Wei Jun Huang,Cun Jun Li,Chun Hui Zhou
Mo, V and W oxides supported on montmorillonite (Mt) have shown good activity in catalytic glycerol oxidehydration. However, these catalysts deactivate rapidly due to coking. Understanding the role of Mo, V and W oxides in coke formation is essential to overcome the coking problem. Herein, individual and combination of Mo, V and W oxides supported on Mt were investigated to reveal the contribution of Mo, V and W oxides to coke formation. Among single metal oxide catalysts, Mo-Mt and W-Mt suffered more from coke formation than V-Mt. A mixture of Mo 5+ and Mo 6+ in the Mo-Mt catalyst hindered full oxidation during the oxidehydration, thus promoting coking. The oxidation of V 4+ to V 5+ helped diminish coke in mixed Mo-V-Mt and W-V-Mt. This work is expected to provide new information for designing high-performance Mo, V and W oxide catalysts with superior coke resistance.
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
Catalysis Science & Technology
·
2019
·Vol. 10
·期 3
·835-843
·
IF 5.726
Yan Zhang,Shide Wu,Xia Xu,Heqing Jiang
Rapid deactivation by coke deposition is the main obstacle of ethane aromatization over Zn/ZSM-5. In this work, using the prepared nanosized Zn/HZSM-5, an almost threefold product yield and significantly improved stability were achieved in comparison with those of the microsized catalyst. XRD and XPS analyses indicated that a higher percentage of reactive [ZnOZn]2+ species was maintained during ethane aromatization over nano-Zn/HZSM-5 than micro-Zn/HZSM-5. In addition, the evolution of carbon deposits over nanosized and microsized Zn/ZSM-5 was investigated during prolonged ethane aromatization reaction using Raman spectroscopy and thermogravimetry measurements. Compared to the microsized catalyst, the nanosized zeolite facilitated the faster escape of light aromatics and the precursors of carbon deposits from the zeolite pores, thus suppressing the accumulation of coke deposits and improving the catalyst stability. Based on the nanosized Zn/HZSM-5, a protocol of isothermal reaction followed by regeneration was developed by periodically removing carbonaceous deposits, and an ∼25–35% product yield was achieved after 10 reaction–regeneration cycles.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
ENERGY
·
2024
·
IF 9
Yuechi Che,Xiaopeng Jia,Yongjie Hu,Jian Li,Zhi Wang,Beibei Yan,Guanyi Chen
Tar catalytic removal is a key issue in biomass gasification , which is suffering from catalyst coking and sintering. Microwave technology is attractive due to the high activity on polar molecules and ability to lower activation energy . In this study, the Co/C derived from metal-organic frameworks (ZIF-67) was developed as a bifunctional microwave catalyst that can strengthen the interaction between microwave and tar catalytic reforming , and enhance the anti-coking and sintering ability. The effects of the temperature, heating method, tar concentration, and catalyst support on model tar conversion rate were investigated. The operating conditions at 700 °C and tar concentration lower than 20 g/m 3 can reach a promising conversion rate over 90.15 % under microwave irradiation . On the one hand, microwave heating groups performed better in conversion rate and coking compared to conventional heating, due to the active species generated from the microwave plasma . On the other hand, Co/C showed better performance in catalytic activity and sintering stability, due to the highly dispersion of cobalt nanoparticles and the confinement effect of carbon nanotubes on the catalyst surface . These findings proposed a novel approach for efficient biomass tar removal under microwave irradiation, and offered a potential tool to further reveal the mechanism in microwave driven tar steam reforming system.
研究领域:
能源与环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2020
·Vol. 10
·期 5
·485
·
IF 3.52
Ming Zhang,Zhen Song,Mengquan Guo,Xiangxiang Li,Yanjun Lin,Lihong Zhang
The effect of reduction atmospheres, H2/N2, C3H8/H2/N2, C3H8and CO, on the structure and propane direct dehydrogenation performance of PtIn/Mg(Al)O/ZnO catalyst derived from ZnO-supported PtIn-hydrotalcite was studied. The physicochemical properties of the as-prepared and used catalytic system were characterized by various characterization methods. The results show that the dehydrogenation performance, especially the stability of the PtIn/Mg(Al)O/ZnO catalyst, was significantly improved along with the change in reduction atmosphere. The highest catalytic activity (51% of propane conversion and 97% propylene selectivity), resistance toward coke deposition, and stability for more than 30 h were achieved with the H2/N2-reduced catalyst. The optimal dehydrogenation performance and coke resistance are mainly related to the high Pt dispersion and In0/In3+molar ratio, strong Pt–In interaction and small metal particle size, depending on the nature of the reduction atmospheres. The reconstruction of meixnerite favors the stability and coke resistance to some extent.Keywords:propane dehydrogenation;reduction atmosphere;coke deposition;meixnerite;PtIn/Mg(Al)O/ZnO
研究领域:
催化
·
化学工程
·
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）