FUEL
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2021
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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
·
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
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2021
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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
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2021
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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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APPLIED CLAY SCIENCE
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2021
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IF 5.467
Xinyu Li,Shunyu Han,Dongdong Guan,Nanzhe Jiang,Jingzhe Xu,Sang-Eon Park
The direct synthesis of H-ZSM-5 catalysts from natural aluminosilicate clays is important for the conversion of raw clay resources to high-value-added products. Herein, the solid-like-state conversion was used to directly prepare nano-H-ZSM-5 with uniform morphology and particle size (~300 nm) from leached illite (ISR) as both Si and Al source. Crystallization kinetics indicated that the reactivity of ISR is similar to that of commercially fabricated products and ISR could be rapidly (within 5 h) converted into nano-H-ZSM-5, the crystallinity , morphology, and crystal size of which were strongly affected by the amount of tetrapropylammonium hydroxide (TPAOH). Additionally, the residual Al of ISR uniformly intruded the H-ZSM-5 framework to provide active sites for the methanol-to-aromatics reaction. The catalytic performance stability and BTX selectivity of nano-H-ZSM-5 for this reaction surpassed those of a commercial ZSM-5 catalyst because of the synergistic effect among the specific surface area and volume of micropores , uniform morphology and particle size, and homogeneously distributed acidic sites. This rapid, efficient, and cleaner synthesis reported herein was shown to have no necessity of ion exchange with ammonium salts, to be H-form of ZSM-5 as well as improve the productivity of HZSM-5 catalysts. And consequently, it is expected to reduce the cost of synthesis and provide an opportunity for the comprehensive development and utilization of illite clay resources.
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CHEMOSPHERE
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2020
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IF 5.778
Xingtao Zuo,Cheng Qian,Senlin Ma,Juan Xiong
Sulfonamides (SAs) in the aquatic environment are a serious threat to human health, environmental ecology and water reuse . Natural organic matter and SAs are known to compete for adsorption sites on adsorbent. SAs adsorption by high silica ZSM-5 (HSZSM-5) affected by humic monomers remains unclear. The impact of representative humic monomers (HMs) (caffeic acid (CA) and vanillin (VNL)) on the sorption of SAs by HSZSM-5 at different pH was evaluated for the first time. Fourier transform infrared and X-ray photoelectron spectroscopy were used to obtain the group transformations. The presence of HM did not change the main adsorption mechanism of SAs on pristine and loaded HSZSM-5 (pH-dependent and hydrophobic interaction). Lewis acid-base electron interaction , π-π electron donor-acceptor (EDA), and H-bonding had a positive contribution to the adsorption of SAs by HSZSM-5 after HM coating. However, HM coating and competition reduced the adsorption capacity of HSZSM-5 towards SAs. In co-introduction system of HM and SAs, the reaction between C O in HM and N–H in SAs resulted in SAs and HM co-adsorbed on HSZSM-5. Meanwhile, CA concentration <20 mg/L was in favor of SMX adsorption. The findings give an insight into the interactions among HM and SAs in high silica zeolites adsorption system, thereby improving SAs removal in actual water.
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PubMed
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
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2020
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IF 4.794
Xiaowei Fang,Ze Wang,Wenli Song,Songgeng Li
In this paper the aldol condensation of furfural (C5) with acetone (C3) over Ca/ZSM-5 was studied with lower dosages of water and acetone as compared to previous studies. It was observed that the formation of CaO over the catalyst is critical to catalyst activity and that the reaction may not occur without water. Although higher quantity of water was favorable for the formation of 4-(2-Furyl)-3-buten-2-one (C8), it was inhibitive for the formation of 1,5-bis-(2-furanyl)-1,4-pentadien-3-one (C13). Highest yields of C8 (38.4 mol%) and C13 (60.2 mol%) were obtained with C3-to-C5 mole ratio of 0.8:1, and water content of 29.7 wt%. The deactivated catalyst was further regenerated by re-loading CaO. An intrinsic kinetic model was established whereby the reaction was first-order dependent on the concentration of each reactant. The formation of 4-(2-furyl)-4‑hydroxy‑butan-2-one (C8-OH), and the C8-OH-to-C8 dehydration were essential steps. The reaction of C8-OH with C5 owned the highest activation energy (41.9 kJ/mol), this step was more sensitive to reaction temperature than those of other steps.
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高影响因子
ACS Sustainable Chemistry & Engineering
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2020
·
IF 7.632
Wen Li,Kuncan Wang,Guowu Zhan,Jiale Huang,Qingbiao Li
The chemical transformation of CO2 to value-added chemicals and fuels remains a daunting research challenge, requiring the development of more efficient catalysts. The present work offers highly active integrated nanocatalysts for CO2 hydrogenation to dimethyl ether (DME) through tandem catalysis, that is, Pd/ZnO converts CO2 to methanol, and bio-ZSM-5 further catalyzes methanol dehydration to DME. Notably, the hierarchically porous bio-ZSM-5 with high pore connectivity was prepared by using low-cost rice husk and luffa sponge as biotemplates. The formation of bio-ZSM-5 involved three consecutive steps, including (i) diffusion of precursor species, (ii) confined crystal growth, and (iii) calcination treatment to remove the residual biomass. Interestingly, the obtained bio-ZSM-5 possesses abundant hierarchical porosity, including the intrinsic micropores from ZSM-5 frameworks, the mesopores from intracrystalline void space or pinholes in the intergrown zeolite layers, and the macroscopic channels from the original biomass architecture. It was found that the tetrapropylammonium hydroxide amount and Si/Al ratio were two critical factors affecting the crystallinity and porosity of the bio-ZSM-5. The silicon content in biomass (8.3 wt % in rice husk and 0.016 wt % in luffa sponge) also played a crucial role in the synthesis of bio-ZSM-5. Different spatial configurations of Pd/ZnO and bio-ZSM-5 significantly affected the DME yield, wherein spatial distances between the bio-ZSM-5 and Pd/ZnO components were adjusted by controlling the size of Pd/ZnO or the integration manners. The current results indicated that the closest proximity of the bifunctional catalyst was unfavorable for DME production (selectivity < 3%), because of which low-valent Zn cations from Pd/ZnO could displace the Brønsted acid sites on bio-ZSM-5 by ion exchange, and the powder mixing in the mortar was the best combination configuration of Pd/ZnO and bio-ZSM-5, promoting the CO2 conversion (10.8%) with a DME selectivity of 31% under the reaction of 300 °C and 30 bar. Furthermore, as compared to the traditional ZSM-5 based catalyst, the obtained Pd/ZnO/bio-ZSM-5 bifunctional catalysts showed excellent long-term stability in 60 h on stream with a less amount of coke formed in the spent catalysts.
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高影响因子
CATALYSIS TODAY
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2020
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IF 5.825
Hong Du,Miao Jiang,Xiuyun Ma,Peifang Yan,Z. Conrad Zhang
The rapid consumption of fossil resources and the grim environmental situation encourage the application of renewable and clean energy resources. Conversion of biomass, which is a kind of renewable, CO 2 neutral as well as abundant reserves carbon containing resource, is significantly important. The production of fuels from biomass by means of gasification and Fischer-Tropsch synthesis is one of the most promising routes for industrial applications. The wax-free liquid fuels synthesis directly from H 2 -deficient syngas similar to bio-gas is highly advantageous for reducing investment and operating cost. Thus, the Mn-promoted meso-ZSM-5 supported cobalt catalyst was applied for the production of wax-free liquid fuels by catalytic H 2 -deficient syngas conversion in this study. The performance of the reaction was influenced obviously by Mn content. The cobalt dispersion increased with the addition of Mn, whereas the reduction degree decreased after Mn doping. Then, the balance between the dispersion and reduction degree led to the change in CO uptake followed a volcanic curve. The catalyst with moderate amount of Mn (1 wt%) had the suitable cobalt particle size and the maximum CO uptake. Thus, the highest CO conversion was obtained over Co-1Mn/meso-ZSM-5 catalyst thanks to its maximum exposed active sites. The appropriate amount of Mn addition also resulted in the decreasing of CH 4 selectivity. The highest space time yield of liquid fuels was acquired over the Co-1Mn/meso-ZSM-5 catalyst from H 2 -deficient syngas conversion under the moderate conditions.
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高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2019
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IF 7.65
Qin Zhu,Jiaorong Yan,Qiguang Dai,Qingqing Wu,Yuanpu Cai,Jinyan Wu,Xingyi Wang,Wangcheng Zhan
A unique zeolite catalyst, Fe doped ZSM-5 microsphere assembled by uniform nanorod-like crystals with hierarchical pore structure, was successfully synthesized and applied for the adsorption and degradation of trace chlorobenzene (CB) in the presence of H 2 O 2 . The organic ferric salts as the precursors, ethylene glycol as a chelating/reducing agent and the dynamic two-stage temperature-varied hydrothermal technique, together made the synthesized hierarchical Fe-ZSM-5 nanorods assembled microspheres (FZ-CA-5EG) to be characterized by abundant highly dispersed and valency-controlled framework Fe 3+/2+ species. As a result of these features, the FZ-CA-5EG showed excellent ability of adsorption and degradation efficiency of CB, and enhanced durability due to negligible leaching of framework Fe species. Moreover, the hydroxyl radicals were determined as the main the reactive oxygen species of CB oxidation degradation, and a possible adsorption-oxidation degradation pathway was proposed.
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PubMed
高影响因子
Materials Research Express
·
2019
·Vol. 6
·期 11
·115540
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IF 1.449
Yong Liu,Qiong Luo,Hao Lu,Zhao Wang
The factors influencing the hydrothermal synthesis of ZSM-5 have been investigated in detail, such as silicon source, template, pH, reaction temperature, etc The type of template plays a key role. It is difficult to synthesize ZSM-5 without template or using inorganic template under our research conditions. However, the organic template of tetrapropylammonium bromide (TPABr) or n-butylamine (BTA) is beneficial to the synthesis of HZSM-5. The pH range of 10.79–11.14 is favorable for the synthesis of HZSM-5 zeolite. When temperature is greater than or equal to 160 °C, the synthesis of target zeolites is easy. However, if temperature is ≤140 °C, the synthesized product belongs to amorphous solid. Scanning electron microscopy (SEM) shows that the morphology of HZSM-5 crystal is hexagonal columnar. Fourier transform infrared (FTIR) analysis shows the synthesized product has a good ZSM-5 skeleton structure. The synthetic HZSM-5 zeolite has the BET specific surface area of about 387.326 m2 g−1. The adsorption capacities of the synthesized HZSM-5 for phenol, quinoline and indole can reach up to 43.54 mg g−1, 83.10 mg g−1 and 69.51 mg g−1, respectively.
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Journal of Water Process Engineering
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2022
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IF 7.34
Bo Jiang,Jinzhe Li,Xinyi Chen,Lu Huang,Shan Luo,Ying Xing,Jing Deng,Shuang Song,Feilong Dong
Exploring an environmentally friendly and highly activation catalysts in the advanced oxidation processes (AOPs) basing on sulfate radicals (SO 4 − •) has shown great importance for the remediation of refractory contaminants. Herein, Fe 3 O 4 -wrapped ZSM-5 (Fe 3 O 4 @ZSM-5) was constructed as heterogeneous catalyst to remove ciprofloxacin (CIP) via peroxymonosulfate (PMS) activation, in which performance, kinetics and mechanism insight were investigated in depth. The removal efficiency of CIP reached 90 % by Fe 3 O 4 @ZSM-5 catalysts within 100 min reaction when the initial pH was 3.0. During the reaction, SO 4 − • and HO• were proved to be coexisted in reaction system and SO 4 − • played a critical role in CIP degradation according to the radical quenching experiments and electron paramagnetic resonance (EPR) measurements. Based on the catalyst characterization and Langmuir-Hinshelwood adsorption kinetics analysis, the synthesis of Fe 3 O 4 nanoparticles (NPs) and ZSM-5 accelerated the dispersion process and enhanced adsorption ability of Fe 3 O 4 NPs, which further promoted the local concentration of CIP and PMS on the surface. In addition, the cycling experiments and metal leaching tests demonstrated that Fe 3 O 4 @ZSM-5 catalysts were stable and could be conveniently reused by magnetic separation. In addition, the impacts of coexisting irons (Cl − , SO 4 2− , NO 3 − , HCO 3 − ) confirmed that Fe 3 O 4 @ZSM-5 was still effective in real water. This study demonstrated the promising prospect of Fe 3 O 4 @ZSM-5/PMS system in the application of degradation refractory organic pollutants .
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