JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
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2022
·Vol. 97
·期 7
·1900-1908
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IF 3.709
Yanjie Wu,Huiping Zhang,Ying Yan
BACKGROUND Cu-ZSM-5 was prepared on paper-like sintered stainless steel fibers (PSSF) by ion-exchange method for the catalytic wet peroxide oxidation (CWPO) of phenol in a fixed bed reactor. The prepared Cu-ZSM-5/PSSF catalyst was characterized by scanning electron microscope (SEM), Brunner−Emmet−Teller (BET), X-ray diffraction (XRD), Fourier Transform InfraRed (FT-IR), Ultraviolet–visiblespectroscopy (UV–vis) and X-ray photoelectron spectroscopy (XPS). RESULTS The XRD results showed that the ZSM-5 membrane was loaded well over PSSF with good crystallinity, even after the process of ion-exchange. The UV–vis inferred that isolated copper was the predominant species over ZSM-5 pores of the catalyst. Then, the effects of different catalyst bed heights, reaction temperatures, and feed flow rates on catalytic performance were investigated to obtain optimum reaction conditions. CONCLUSIONS Finally, the catalytic reaction kinetics analysis over Cu-ZSM-5/PSSF catalyst were carried out with the Power-rate Law Kinetic model. The experimental results showed that the reaction order was the first-order reaction, and the activation energy of the oxidation reaction was Ea = 72.9 kJ/mol. The initial oxidation rate equation (−r A0 = 5.36 × 10 8 e −72 994/RT C A ) was obtained for phenol degradation using Cu-ZSM-5/PSSF catalyst. © 2022 Society of Chemical Industry (SCI).
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高影响因子
Applied Sciences-Basel
·
2022
·Vol. 12
·期 8
·3769
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IF 2.838
Wei Ma,Dong Ye,Haining Wang
Herein, a series of Co-Fe mixed oxide modified ZSM-5 adsorbents were synthesized using the ultrasonic-assisted impregnation method for the capture of elemental mercury. In comparison with other samples, Co4Fe1-ZSM-5 produced a relatively better performance, with the removal efficiency of around 96.6% Hg0and the adsorption capacity of around 901.63 ug/mg Hg0achieved at 120 °C. The interaction between CoOxand FeOximproved the reducibility of oxygen species, thus promoting the oxidation of Hg0. Among a variety of other gas components, O2and NO exerted a positive effect on Hg0, which improved its removal to a certain extent. By contrast, SO2caused an adverse effect on the capture of Hg0, which could be reversed to some degree by the introduction of 5% O2. After five cycles, the mercury removal efficiency of Co4Fe1-ZSM-5 remained above 90%, suggesting excellent recyclability. Finally, XPS analysis was conducted to reveal that Mars–Maessen mechanisms are dominant in the process of mercury adsorption.Keywords:Hg0adsorption;ZSM-5;cobalt oxide;iron oxide;regeneration
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CHEMICAL ENGINEERING SCIENCE
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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.
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CHEMOSPHERE
·
2022
·
IF 8.943
Guohua Li,Xianjin Qi,Nina Yang,Xiaoxu Duan,Aimin Zhang
Molecular sieves have also been used for arsenic adsorption in recent years because of their special structure. In order to solve the problem of arsenic pollution in drinking water and/or industrial wastewater , ZSM-5/Fe adsorbent was prepared by loading iron on ZSM-5 molecular sieve. It is also used as an excellent adsorbent for removing arsenic and other heavy metal ions from industrial wastewater. At room temperature, the concentration of arsenic was reduced from 100 mg/L to 0.006 mg/L after the solution pH was adjusted to the range of weak acid to weak base (4–10) and 0.5 g of ZSM-5/Fe adsorbent was added for reacting 2 h. The adsorption capacity reached 40.00 mg/g, the adsorption efficiency reached 99.99%, reaching the national standard of drinking water. Adsorption thermodynamics, kinetics and isotherms showed that the adsorption mechanism of arsenic is heterogeneous nucleation adsorption (including electrostatic attraction and chemical precipitation). Moreover, ZSM-5/Fe adsorbent can adjust pH spontaneously by using non-skeleton Si–Al phase to achieve effective adsorption from weak acid to weak base. At the same time, ZSM-5/Fe adsorbent showed good reusability and stability in five cycles. This study provides an important idea for the application of ZSM-5 molecular sieve in many fields and the efficient removal of arsenic from drinking water and industrial wastewater.
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PubMed
高影响因子
Processes
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2022
·Vol. 10
·期 10
·1970
·
IF 3.352
Xuan Zhou,Hongling Pan,Shuixiang Xie,Guotao Li,Zhicai Du,Xiang Wang,Yan Luo
The aim of this research is to design and synthesize an efficient catalyst to enhance high value-added products, such as aromatic hydrocarbons and phenols, from the catalytic fast pyrolysis (CFP) of different types of forestry and agricultural residues. All three biomasses (rape straw, wheat straw, and bamboo powder) had no aromatic production via thermal pyrolysis alone; however, the aromatic selectivity and monocyclic aromatic selectivity were largely enhanced using ZSM-5, with suitable silica-alumina ratios and Ni loadings. Specifically, for rape straw, the optimum catalyst was 15 wt.% Ni/ZSM-5 (silica-aluminum ratios = 85), and the selectivity of aromatic hydrocarbons was achieved at 39%, of which 71% were monocyclic aromatic hydrocarbons. For wheat straw, the optimum catalyst was 10 wt.% Ni/ZSM-5 (silica-aluminum ratios = 18), and the selectivity of aromatic hydrocarbons was 67%, of which 55% were monocyclic aromatic hydrocarbons. For bamboo powder, the optimum catalyst was 10 wt.% Ni/ZSM-5 (silica-aluminum ratios = 18), and the selectivity of aromatic hydrocarbons was achieved at 21%, of which 80% were monocyclic aromatic hydrocarbons. Meanwhile, biomass types have significant effects on the pyrolyzed product distribution due to their different components. Cellulose and hemicellulose promoted the production of aromatic hydrocarbons, while lignin enhanced the production of phenols. The promotion of phenol by Ni was better and more efficient than that by the molecular sieve.Keywords:catalytic fast pyrolysis;forestry and agricultural residues;Ni/ZSM-5;aromatic hydrocarbons;phenols;Py-GC/MS
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MICROPOROUS AND MESOPOROUS MATERIALS
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2022
·
IF 5.876
Haochen Qi,Chuang Xing,Weiguo Huang,Mingquan Li,Yujia Jiang,Xu Sun,Heyang Liu,Peng Lu,Jiangang Chen,Shuyao Chen
Fischer-Tropsch (FT) synthesis as a strongly exothermic reaction has diffusely manufactured clean fuels from syngas. However, it is difficult to obtain the concentrated product distributions. Here, we design ZSM-5 encapsulated cobalt particles on the thermal conductivity of the SiC matrix. The Co@NaZSM-5/SiC capsule catalyst with hierarchical structure is ingeniously assembled through a solvent-free synthesis route. Due to the joint functions of acidic zeolite , SiC thermal conductivity and macropores, the olefin selectivity enhances to 32.3% on the Co@NaZSM-5/SiC catalyst. Moreover, the ratio of O 5-11 /C 5-11 approaches 49.1% suggesting the elevated middle olefin proportion. The H + ion-exchanged Co@HZSM-5/SiC capsule catalyst shows a high isoparaffin selectivity of 27.3%, since the olefin isomerization reaction is accelerated over strong acid sites. Besides, Co 2 C phase is readily formed during the FT reaction, which is an activity center for olefin synthesis. The capsule catalyst with the proper acidity, thermal conductivity, and hierarchical structure is a promising prospect for tuning production distribution in FT reaction.
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APPLIED CATALYSIS A-GENERAL
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2022
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IF 5.723
Ge Yang,Xi Yan,Yan Chen,Xiao-Jing Guo,Wan-Zhong Lang,Ya-Jun Guo
In recent years, Ga-based catalysts attract much attention in propane dehydrogenation (PDH) reaction due to environmental friendliness and low cost. Nevertheless, it is still challenging to obtain high selectivity of propylene under harsh reaction conditions. In this work, the supported catalysts (Ga- x Mg/ZSM-5) were prepared with the sequential impregnation method and applied in the PDH reaction. The results show that MgO as an additive reduces the acidity of the catalysts, promotes the dispersion of Ga 2 O 3 and improves the selectivity of propylene. As a result, the average particle size of the Ga/ZSM-5 catalyst is larger (4.5 nm), and the initial propylene selectivity is only 71.0 %. In contrast, the optimal Ga-0.7Mg/ZSM-5 catalyst shows the smallest particle size (2.4 nm) and the highest propylene selectivity of 90.8 %. In comparison with the previous GaO x catalysts in literatures, the Ga-0.7Mg/ZSM-5 catalyst exhibits a superior production rate of propylene ( r C 3 H 6 ) based on either catalyst weight or Ga 2 O 3 weight.
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高影响因子
FUEL
·
2022
·
IF 8.035
Fuwei Li,Xiaofeng Wang,Hengshuo Gu,Hongbing Fu,Asad Ali,Hongfei Lin,Zhixia Li
Minimizing the catalyst cost is critical to achieving long-term economic feasibility for obtaining bio-chemicals directly from biomass. In the present study, low cost ZSM-5 was synthesized via hydrothermal crystallization of the activated aluminosilicate gel without adding any organic ammonium templates and additional seed crystals . The activation process promoted the depolymerization of the silica-alumina species and the formation of active pasty gel containing nucleation precursors, consequently accelerating the subsequent crystallization reaction. The addition of eucalyptus sawdust (ES) in the synthesis process increased the BET (Brunauer-Emmett-Teller) surface area and acidity of the resultant zeolites . The ES-mediated ZSM-5 (AGZ-10) achieved a higher benzene, toluene, ethylbenzene and xylene (BTEX) carbon yield (18.9 %) from co-cracking of ES and waste plastics (WP) (ES/WP mass ratio at 1:1) at 500 °C and exhibited better synergistic effect and anti-coking ability compared to the commercial ZSM-5. The results provide an efficient synthetic strategy to produce low-cost zeolites, and a promising technique to effectively utilize biomass and plastic wastes.
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高影响因子
FUEL
·
2021
·
IF 6.609
Tao Pan,Sida Ge,Mengnan Yu,Yana Ju,Ran Zhang,Pei Wu,Kuanyu Zhou,Zhijie Wu
Zn modified ZSM-5 zeolite supported Ni bifunctional catalysts were prepared by in-situ hydrothermal synthesis (Zn-Ni-ZSM-5), co-impregnation method (Zn-Ni/ZSM-5) as well as combining in-situ hydrothermal synthesis of Zn-ZSM-5 and sequential impregnation of Ni (Ni/Zn-ZSM-5) and used for the selective converting olefin to aromatics applicable for FCC gasoline hydro-upgrading. The Lewis (L) acid sites generated by ZnOH + species and hydrogenation active sites from Ni 0 species were varied with preparation method, in which their locations at the external surface or micropores of zeolite changed the acid properties of catalysts. Comparing to the Zn-Ni/ZSM-5 from the co-impregnation method, direct in-situ hydrothermal method could incorporate Zn and Ni species within zeolite, which makes the strong interaction between the metal species and the framework Al to form medium-strong L acids (ZnOH + /NiOH + ). This leads to the decrease of ratio of Brønsted acid sites to L acid sites (B/L) from 0.40 to 0.12 and the difficulty in reducing of Ni cations to Ni 0 from 57% to 30% Ni 0 percent. Ni/Zn-ZSM-5 sample prepared by incorporating Zn species into micropores and sequential depositing Ni species at the external surface of zeolite possesses a low B/L ratio similar to Zn-Ni-ZSM-5 (0.20 versus 0.12) but a much higher Ni 0 percent (52% versus 30%). Zn-Ni-ZSM-5 shows closer intimacy between Zn and Ni species comparing to Zn-Ni/ZSM-5 and Ni/Zn-ZSM-5. For the 1-hexene aromatization, the formed iso -alkene at acid sites was quickly saturated to iso -alkanes by the adjacent Ni 0 particles over Ni-Zn-ZSM-5 catalyst in hydrogen steam. However, the location of aromatization active sites (ZnOH + , L acid sites) in micropores and hydrogenation active sites (Ni 0 species) on external surface of Ni/Zn-ZSM-5 makes the tandem conversion of n-alkene → iso -alkene → aromatics, rather than the n-alkene → iso -alkene → iso -alkane. Thus, Zn-Ni-ZSM-5 with close intimacy of ZnOH + and Ni 0 particles shows a high iso -alkane selectivity (27.9% iC 4 + ), while Ni/Zn-ZSM-5 exhibits a high aromatics selectivity (39.6 %) in the conversion of 1-hexene in hydrogen steam. Similar results have also found in the conversion of n-heptane. Here, the control of the intimacy of Zn and Ni in ZSM-5 zeolites has been realized to be a good protocol to adjust the selective conversion of olefins/alkanes to aromatics versus iso -alkanes.
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高影响因子
ACS Sustainable Chemistry & Engineering
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2021
·
IF 8.198
Wen Li,Kuncan Wang,Guowu Zhan,Jiale Huang,Qingbiao Li
Transformation of CO2 with the help of green hydrogen (prepared from renewable energy) into valuable light olefins (C2=–C4=) is a promising route for utilizing the carbon resource in CO2. Currently, most of the reported bifunctional catalysts for CO2 hydrogenation to light olefins follow a methanol-mediated route that adopts SAPO-34 as the zeolite component. Although ZSM-5 has been widely used in the methanol to propylene process using fixed bed reactors due to high shape-selective property and long lifetime, ZSM-5-based bifunctional catalysts have seldomly been used for CO2 hydrogenation to light olefins. Herein, we proposed a novel synthetic strategy for bio-ZSM-5 with mild acid strength and relatively low acid density using the natural rice husk as a template. The bio-ZSM-5 was integrated with ZnZrOx solid solution nanoparticles, and the derived ZnZrOx&bio-ZSM-5 catalysts exhibited a high C2=–C4= selectivity of 64.4% and total C2–C4 selectivity of 94.5%, but relatively low CH4 selectivity (5.5%) and aromatic selectivity (<1%). The post-modified ZnZrOx&bio-ZSM-5 catalysts further enhanced the catalytic stability with less coke deposition and regulated the ethylene to propylene ratio in light olefin distribution. Furthermore, *CHxO was found to be the key intermediate formed on the ZnZrOx surface and was transferred to the Brønsted acid sites in the bio-ZSM-5 for the subsequent conversion to light olefins, as confirmed by in situ DRIFTS and chemical trapping mass spectrometry.
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高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xiao Zhao,Xuan Shi,Zhongshun Chen,Long Xu,Chengyi Dai,Yazhou Zhang,Xinwen Guo,Dongyuan Yang,Xiaoxun Ma
A series of ZnO-ZrO 2 solid solutions with different Zn contents were synthesized by the urea co-precipitation method, which were coupled with H-ZSM-5 zeolite to form bifunctional catalysts. As a new benzene alkylation reagent, syngas was used instead of methanol to realize the efficient conversion of syngas and benzene into toluene and xylene. A suitable ratio of ZnO-ZrO 2 led to the significant improvement in the catalytic performance, and a suitable amount of acid helped to increase the selectivity of toluene/xylene and reduce the selectivity of the by-products ethylbenzene and C 9 + aromatics. The highest benzene conversion of 89.2% and toluene/xylene selectivity of 88.7% were achieved over 10% ZnO-ZrO 2 &H-ZSM-5 (Si/Al = 23) at a pressure of 3 MPa and a temperature of 450 °C. In addition, the effect of the zeolite framework structure on product distribution was examined. Similar to the molecular dynamics of aromatic hydrocarbons , H-ZSM-5 zeolites comprise 10-membered-ring pores, which are beneficial to the activation of benzene; hence, the conversion of benzene is higher. H-ZSM-35 and H-MOR zeolites exhibited small eight-membered-ring channels, which were not conducive to the passage of benzene; hence, the by-product ethylbenzene exhibits a higher selectivity. The distance between the active centers of the bifunctional catalysts was the main factor affecting the catalytic performance, and the powder mixing method was more conducive to the conversion of syngas and benzene.
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高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Yi Yang,Huiqi Zhu,Xuhui Xu,Lulu Bao,Yinuo Wang,Haowen Lin,Chenyang Zheng
Eutrophication caused by excessive phosphate has become a global environmental issue that urgently needs to be solved due to its destructive effect on the ecosystem and adverse effect on human health. In this study, a novel lanthanum carbonate-grafted ZSM-5 zeolite (LC-ZSM-5) was developed to effectively achieve highly selective phosphate removal from wastewater. The LC-ZSM-5 adsorbent shows high adsorption capacity (highest at over 45 mg-PO 4 3- /g) in the pH range of 3–6 with a fast adsorption rate (reaching 80% of the maximum adsorption capacity within 150 min and equilibrium at 350 min). High stability can be observed with less than 0.3 mg/L La leakage during the adsorption process . Four kinetic models are used to describe the adsorption process. The pseudo second order model and the Elovich model are found to fit the data best with a high correlation coefficient (r 2 = 0.99), showing that the adsorption process is influenced simultaneously by the phosphate concentration and interaction between adsorbent and adsorbate. The change of curve slope from 4.0 to 0.89 and intercept from 0.76 to 27.6 in intra-particle model indicates that the adsorption process is controlled by a combination of intra-particle diffusion and film surface diffusion . The maximum phosphate adsorption capacity calculated from the Langmuir model is 47.7 mg-PO 4 3- /g, and the adsorption isotherm data are fitted well by the Freundlich model (r 2 = 0.95) and the Koble-Corrigan model (r 2 = 0.95), suggesting that the phosphate adsorption process is dominated by nonregular multilayer adsorption with the coexistence of monolayer adsorption. The ionic strength and co-existing anions have little impact on the adsorption capacity of LC-ZSM-5, proving the adsorption selectivity of phosphate onto LC-ZSM-5. Characterization results show that spindle-like lanthanum carbonate particles are fabricated on ZSM-5. Combining the adsorption process and the characterization, it can be derived that phosphate is adsorbed by LC-ZSM-5 mainly through electric attraction and ligand exchange. Our study demonstrates the great potential application value of LC-ZSM-5 in commonly seen phosphate-containing wastewater.
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高影响因子
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