CRYSTENGCOMM
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2021
·Vol. 23
·期 15
·2793-2800
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IF 3.545
Xueshuai Chen,Rongli Jiang,Yu Gao,Zihan Zhou,Xingwen Wang
In this work, nano-ZSM-5 zeolite with superior catalytic properties was synthesized from LAPONITE® as one of the Si sources by a dry gel conversion (DGC) method, and its crystallization mechanism was investigated as well. The properties of ZSM-5(Z-L) synthesized from LAPONITE® as one of the Si sources and ZSM-5(Z-T) synthesized from tetraethylorthosilicate (TEOS) as a single Si source have been compared. The results show that LAPONITE® is an important factor for the formation of nanocrystals with high crystallinity. It can not only act as the Mg and Si source for the zeolite synthesis but also exert a “confined space” effect to control ZSM-5 crystal growth. The Z-L sample with nanosized crystals can shorten the reactant and product diffusion path length, which seriously improves diffusion efficiency and results in longer catalytic stability. This work provides a novel and efficient route for synthesis of nano-ZSM-5 zeolite.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2021
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IF 4.539
Jingyi Liu,Shuhua Han,Yongfeng Hu,Chih-Wen Pao
A highly sensitive and low-cost optical nanosensor of organic-inorganic hybrid material for pesticide ferbam detection was prepared by utilizing a novel organic siloxane precursor obtained from riboflavin-5′-phosphate sodium salt (Rf). A panel of characterizations was carried out to understand the structure, morphology and surface chemistry of the Rf periodic mesoporous organosilica (Rf-PMO) spherical nanosensors. For the Rf-PMO materials, the doped silica nanoparticles exhibit strong fluorescence emission at 520 nm, on account that the greater steric hindrances and the more separated state of π-conjugate planer platforms between Rf molecules embedded within the silica framework can both enhance the fluorescence emission and reduce the self-quenching of fluorescence produced by stacking aggregation of Rf. The electron spin resonance (ESR) spectra prove that the prepared Rf-PMO materials can participate in the redox reaction through electron transfer with the pesticide ferbam. Utilized the reducing reaction mechanism of Rf-PMO, it is applied to detect pesticide ferbam with high sensitivity and selectivity, with the limit of detection (LOD) in aqueous solution as low as 6.97 × 10 −9 M. Moreover, the X-ray absorption near-edge spectroscopy (XANES) of Fe K -edge shows a coordination structure through the interaction between iron ions from ferbam and O and N atoms in Rf-PMO. X-ray photoelectron spectroscopy (XPS) further reveals the redox mechanism. Therefore, the designed and prepared Rf-PMO is potentially valuable to food safety monitoring involving ferbam as the nanosensor, due to its hypersensitivity and selectivity.
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CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Yubo Pan,Yali Zhang,Yaoguo Huang,Yun Jia,Linlin Chen
Cyanide wastewater contains highly toxic contaminants such as free cyanide and metal-cyanide complex, it is necessary to find the appropriate degradation technologies. In this study, a simple and effective photocatalyst with enhanced adsorption and photocatalytic activity was developed. A new composite photocatalyst was successfully prepared by solid-state dispersion (SSD) method, which combined graphene oxide (GO), nano titanium dioxide (nano-TiO 2 ) and silicon-based zeolite (ZSM-5). The techniques of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), N 2 adsorption–desorption test, X-ray diffraction (XRD), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) were used to characterize the samples. The experiments with different content of nano-TiO 2 , different wavelengths of light source, different catalyst dosage, control experiments of different materials, and the determination of pH value and zeta potential were also carried out. The results showed that the 3.0 g/L of GTZ-60 (GO/TiO 2 /ZSM-5 composite photocatalyst with a content of 60 wt% TiO 2 ) has the highest photocatalytic degradation efficiency under ultraviolet wavelength which the degradation efficiency of total cyanide and copper could reach 98.73% and 98.96%, respectively. The degradation of total cyanide followed the pseudo-first-order kinetics. The photoelectric properties of GTZ-60 obviously improved the migration and separation of photogenerated electrons ( e − ) and holes ( h + ), so that high photocatalytic efficiency was obtained. XPS analysis showed that cyanide was finally degraded to carbon oxide and nitrogen oxide. Copper and zinc are removed in the form of copper (Ⅱ) and zinc (Ⅱ).
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2021
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IF 3.764
Hailin Zhao,Bingjing Tang,Jie Tang,Yafeng Cai,Yao Cui,Hao Liu,Li Wang,Yunsong Wang,Wangcheng Zhan,Yanglong Guo,Yun Guo
Catalytic oxidation is believed to be the most efficient method for indoor formaldehyde purification. Herein, we reported that the Pt/Na-ZSM-5 catalyst with low Pt loading (0.16 wt %) prepared by depositing Pt on Na+ ion-exchanged ZSM-5 could completely oxidize 300 ppm formaldehyde in 2.5 vol % H2O at 32 °C and maintain its activity during the 62 h-long stability test. Multiple characterizations revealed that the presence of Na species significantly enhanced formaldehyde adsorption ability and made Pt species tend to exist in the form of metal Pt through electron transfer from Na to Pt, which promoted the activation of oxygen and opened a new efficient formaldehyde oxidation pathway, namely, direct decomposition of formate. The synergistic effects resulted in the TOF of Pt(0.16)/Na-ZSM-5 being about nine times higher than that of Pt(0.50)/ZSM-5. Our study showed that utilizing an alkali metal to tune the surface acidity/basicity of the support and the state of the supported noble metal was a promising way to improve the intrinsic catalytic performance and reduce noble metal usage.
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Journal of Energy Chemistry
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2021
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IF 9.676
Zhiguo Zhu,Xiongjie Gao,Xiuming Wang,Mengdie Yin,Qingyao Wang,Wanzhong Ren,Bo Wang,Hongying Lü,Weiping Liao
The selective aerobic oxidation of biomass-derived 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid (FDCA, a potential renewable substitution of fossil-based terephthalic acid to produce polyethylene 2,5-furandicarboxylate plastic) is an appealing transformation for constructing eco-friendly and sustainable chemical processes. Au supported catalysts have showed encouraging performances for this well-received conversion, whose catalytic behavior was greatly affected by the adopted support derived from the existence of metal-support interactions. Herein, a series of Mg-Beta zeolites were hydrothermally synthesized via developed structural reconstruction, which were employed as basic supports for Au catalysts to construct bifunctional catalysts. The relationship between structure (Au particle size, basicity within zeolites and Au δ+ contents) and FDCA yield was concretely established. The conclusion was made that the utilization of Mg-Beta zeolites with strong basicity as the support could not only improve the FDCA yield but also decrease the amount of additional base. Furthermore, the possible reaction mechanism was also proposed via tracking time-dependent variations of corresponding organics and controlled experiment. This work provides some guidance for rationally designing multifunctional catalysts in the view of integrating metal catalysts with metallosilicate zeolites, which was beneficial to the catalytic upgrading of organic compounds with multiple functional groups.
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ENERGY
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2020
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IF 6.082
Yuchen Ya,Xiaokang Nie,Weiwei Han,Longkai Xiang,Mingyan Gu,Huaqiang Chu
The effects of 2, 5-dimethylfuran (DMF)/ethanol addition on the atomized combustion soot formation characteristics of n-heptane/iso-octane coflow diffusion flames are systemically studied. The changes of soot particles and deposition morphology at different heights in the flame of reference fuel with 15% ethanol (E15) and 15% DMF (DMF15) are analyzed. Results show that the addition of oxygenated fuels can increase the flame heights and decrease the brightness. With the addition of 15% ethanol and DMF, the flame heights are increased by 11.29% and 19.35% respectively, and the brightness of the edge region of the middle section of DMF15 flame is enhanced. At the nozzle, the average temperature of E15 flame increases by 80 K. The high temperature region of E15 flame enlarged and the average temperature difference of different heights is higher than 50 K. As for DMF15, the high temperature region of flame is constant, and the average temperature difference between various heights is smaller than 35 K. For three fuels, the size of the sediment particles formed at the low height above burner (HAB = 20 mm) is large, and the obvious pore structure can be seen at HAB = 60 mm. The addition of oxygenated fuels makes the pore structure distribution regular and the porosity decreases, and DMF15 (porosity = 0.2670) has larger pore structure than E15 (porosity = 0.1557). The oxygenated fuel can inhibit the formation of soot precursors and the agglomeration of soot particles, but the increase of particle size in the middle region of flame is promoted because of the increase of flame height and residence time of soot particles. As a result, the soot particle size of oxygenated fuel is decreased greatly in the oxidation stage, and the soot particle size of DMF15 (40.4%) is decreased more than that of E15 (37.1%). The effect of ethanol and DMF addition on the activation energy of low position soot is not obvious, which is about 130 kJ/mol. In the middle position of the flame, the activation energy of E15 is the highest (159.32 kJ/mol), and the activation energy of DMF15 is the smallest (148 kJ/mol). At the high position, E15 (212.07 kJ/mol) and DMF15 (226.73 kJ/mol) are less than that of DE0 (235.03 kJ/mol) respectively, indicating that the activation energy of the mature soot reduces, which is beneficial to the oxidative removal. Ethanol can dilute the fuel and increase the oxygen concentration in the mixture, while DMF can delay the ignition and prolong the residence time of soot and increase the content of disordered carbon in mature soot particles.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Qi Lu,Yuanzhe Gong,Jianwen Lu,Jian Liu,Yulong Wu
Stearic acid (SA) and hexadecanamide (HA), which are model compounds of algae-based bio-oil, were used to produce aromatics for catalysis by a hierarchical HZSM-5 zeolite under hydrothermal conditions. The results showed that the hierarchical HZSM-5 zeolite was more active than the traditional HZSM-5 parent zeolite. The molar yield of toluene, ethylbenzene, and xylene could reach (1.14 ± 0.05) × 100% (normal weight percentage yield = 40.77 wt %) when the reaction temperature was 400 °C. Moreover, the catalyst was stable and recyclable under hydrothermal conditions. Besides, the addition of acetic acid remarkably improved the deoxygenation (or denitrification) and aromatization efficiencies of the SA and HA mixture by more than 25%. This study provides a feasible approach to the valorization of algal biomass and the production of aromatics.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2020
·
IF 4.551
Chunhui Cheng,Guixian Li,Dong Ji,Yu Zhao,Jianyi Shen
HZSM-5 is a widely used catalyst for the conversion of methanol to aromatics (MTA), but its single micropore system often results in severe diffusion limitations, leading to the decrease of reaction rate and the change of selectivity to aromatics, as well as affecting the carbon deposition and catalyst deactivation . Thus, an ingenious protective desiliconization method with a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide as a desiliconization agent was developed to create hierarchical porous systems without destruction of the main structure of the molecular sieve . Such modification leads to the greatly increased mesoporous volume from 0.12 to 0.38 cm 3 g −1 , and only slightly decreased microporous volume from 0.12 to 0.09 cm 3 g −1 . However, the desiliconization sharply increases the acidity of the catalyst (from 0.248 to 0.341 mmol g −1 for the strong acid sites), which may significantly affect the distribution of aromatics and accelerate the carbon deposition rate . Thus, the deposition of inert SiO 2 on the catalyst surface is subsequently carried out to passivate the surface acidity and adjust the orifice of the catalyst. Accordingly, a hierarchical porous HZSM-5 molecular sieve catalyst (Si@Z5-Na + TP) with suitable acidity is precisely prepared, which exhibits the high selectivity to benzene, toluene and xylenes (BTX) with the excellent anticoking ability in the MTA reaction. The selectivity to BTX in aromatics (63.32%) and the carbon deposition rate (0.91 mg g cat −1 h −1 ) over the Si@Z5-Na + TP catalyst are both much more superior than those over the parent HZSM-5 catalyst (47.5% and 2.23 mg g cat −1 h −1 , respectively).
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2020
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IF 2.627
Huan Li,Yao Zhong,Luxi Wang,Qiang Deng,Jun Wang,Zheling Zeng,Xinxiang Cao,Shuguang Deng
In the dehydration of fructose to 5-hydroxymethyl furfural (HMF), in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF, causing unsatisfactory catalytic activity and selectivity. In this work, a class of benzenesulfonic acid-grafted metal–organic frameworks with strong acidity and hydrophobicity is obtained by the direct sulfonation method using 4-chlorobenzenesulfonic acid as sulfonating agent. The resultant MOFs have a specific surface area of greater than 250 m 2 ·g −1 , acid density above 1.0 mmol·g −1 , and water contact angle up to 129°. The hydrophobic MOF-PhSO 3 H exhibits both higher catalytic activity and selectivity than MOF-SO 3 H in the HMF synthesis due to its better hydrophobicity and olephilicity. Moreover, the catalyst has a high recycled stability. At last, fructose is completely converted, and 98.0% yield of HMF is obtained under 120 °C in a DMSO solvent system. The successful preparation of the hydrophobic acidic MOF provides a novel hydrophobic catalyst for the synthesis of HMF.
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Arabian Journal of Chemistry
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2020
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IF 4.762
Muhammad Sajid,Yuchen Bai,Dehua Liu,Xuebing Zhao
Fructose was converted to 5-hydroxymethylfurfural (HMF), an important biomass-derived platform chemical, under mild conditions (100–130 °C) with several organic acids including p -toluene sulfonic ( p TSA), oxalic, maleic, malonic and succinic acids as the catalysts. The process kinetics was compared considering fructose dehydration to HMF as the objective reaction and condensation of fructose and HMF to humin and rehydration of HMF as the main side reactions. DMSO was found to be the most effective solvent reaction medium to obtain high fructose conversion and HMF yield. Observed kinetic modeling illustrated that the rehydration and condensation of HMF in DMSO actually could be neglected, especially for the oxalic acid catalyzed system. The determined observed activation energy for fructose conversion to HMF and humin in DMSO medium was 33.75 and 24.94 kJ/mol for p TSA catalyzed system, and 96.51 and 78.39 kJ/mol for oxalic acid-catalyzed system, respectively. HMF yields of 90.2% and 84.1% were obtained for p TSA and oxalic acid catalyzed systems, respectively.
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BIORESOURCE TECHNOLOGY
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2020
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IF 7.539
Kai Li,Guan Zhang,Ze-xiang Wang,Bin Hu,Qiang Lu
An efficient process was developed to selectively produce monocyclic aromatic hydrocarbons (MAHs) from ex-situ catalytic fast pyrolysis (CFP) of pine assisted with calcium formate (CF) over bimetal-modified HZSM-5. Mo and another metal (Mg, Ga or Zn) were used to modify the HZSM-5, and the as-synthesized bimetal-modified HZSM-5 catalysts were utilized for both pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale CFP tests with CF as a hydrogen donor to selectively obtain MAHs. The results revealed that the presence of CF and Mg-Mo modified HZSM-5 (0.5Mg1Mo/HZ) exhibited excellent capability for MAHs production with tiny generation of polycyclic aromatic hydrocarbons (PAHs). The maximum MAHs yield attained 12.79 wt% at 650 °C from Py-GC/MS with the CF-to-pine (CF-to-PN) ratio of 3 and catalyst-to-pine (CA-to-PN) ratio of 11, and became 9.67 wt% from lab-scale device with CF-to-PN and CA-to-PN ratios of 0.5 and 4, respectively. In addition, compared with HZSM-5, 0.5Mg1Mo/HZ possessed better anti-deactivation ability.
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PubMed
高影响因子
ANALYTICA CHIMICA ACTA
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2020
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IF 5.977
Kang Luo,Haicheng Chen,Qing Zhou,Zhihong Yan,Zhengquan Su,Kang Li
Calcium fluoride (CaF 2 ) quantum dots have many applications in various fields. But there is no report on fluorescent characteristics of CaF 2 quantum dots (CaF 2 QDs). Here, a synthesis of multiple-color emission CaF 2 QDs by changing the temperature, time and raw ratio is reported, by which the CaF 2 QDs with purple, blue, green, and yellow emission can be obtained, respectively. They were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). On this basis, a novel molecular imprinting ratiometric fluorescence sensor (MIR sensor) had been constructed based on the prepared CaF 2 QDs and CdTe QDs, in which the yellow emission CaF 2 QDs was used as a responsive signal material and the red emission CdTe QDs was served as a reference signal material. And the β-CD and methylacrylic acid (MAA) as bifunctional monomers were used for constructing the specific molecularly imprinted polymers (MIPs) in MIR sensor. This MIR sensor was applied for highly selective and excellent sensitive detection of 5-hydroxymethylfurfural (HMF). Under optimum conditions, it exhibited an excellent linear relationship between the fluorescence intensity ratio (I 599 /I 625 ) and the concentration of HMF in the range of 0.1–6.0 μg/mL with a detection limit of 0.043 μg/mL. Finally, the established HMF-MIR sensor was successfully utilized to detect HMF in honey with satisfactory results. This work provided a reference for the application of the CaF 2 QDs and the detection of the furfural substances.
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PubMed
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