INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
·
IF 3.764
Yujing Chen,Jipeng Meng,Di Bai,Chuang Li,Xiao Chen,Changhai Liang
Pt/xFe/ZSM-23 catalysts with various Fe contents were prepared to explore the influence of extra-framework Fe (EF-Fe) on the n-hexadecane (n-C16) hydroisomerization performance. UV–vis and 57Fe Mössbauer spectroscopic results suggest that the Fe species composition was significantly different under various Fe contents, with (HO–Fe(III)–O–Fe(III)–OH) and [Fe(OH)2]+ as the main Fe species at low Fe content (<1.98 wt %), whereas the Fe2O3 clusters/particles as the dominant ones at high Fe content (>1.98 wt %). Moreover, the concentration of Brønsted acid sites and Pt dispersion could be controlled by tailoring the Fe content. Correspondingly, the hydroisomerization performance of n-C16 over Pt/xFe/ZSM-23 catalysts was dramatically changed with various Fe contents. The Pt/1.98Fe/ZSM-23 catalyst with 1.98 wt % EF-Fe content exhibited considerably excellent hydroisomerization performance, and both n-C16 conversion and selectivity to iso-hexadecane (i-C16) could reach over 80 wt % when the reaction temperature was 310 °C.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Haoqiang Sheng,Xiaobin Huang,Yuan Ji,Zhengchuang Zhao,Wenbin Hu,Junming Chen,Zemin Ji,Xiangzhao Wang,Hong Liu
Soot is carbonaceous particulate produced by incomplete combustion of hydrocarbon fuel, reducing the efficiency of energy utilization and affecting the environment and people’s health adversely. Naphthenic hydrocarbons are essential components in diesel and kerosene, generating great quantities polycyclic aromatic hydrocarbons (PAHs) and subsequently soot particles in the combustion process at high temperature. In this study, a new strategy of cycloalkane combustion at low temperature is developed to reduce the formation of the PAH soot-precursors in the combustion process to decrease soot emission. Borane-dimethyl sulfide (BDMS) and n- hexadecane were employed to promote the low-temperature ignition of cycloalkanes and the reduction of soot emission. By adding of 5% BDMS, the ignition temperature of hybrid fuel 10 (10 vol% n- hexadecane, 90 vol% cyclohexane) decreased drastically from 570 °C to 213 °C and PAH formation was reduced by 87%. In the flame development stage of the combustion process, the flame of BDMS/hybrid fuel 10 appears green in color and is larger than the blue flame in the stage of flame reduction, indicating the complete combustion of cycloalkane fuels. By this strategy of low-temperature combustion, the generation of PAH during combustion of cyclohexane decreases, thereby reducing the generation of soot and improving hydrocarbon fuels utilization.
研究领域:
燃烧工程
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Xiaojun Dai,Yan Cheng,Qiang Wei,Meng Si,Yasong Zhou
In order to prepare non-noble metal supported hydroisomerization catalyst with high catalytic performance, this work first proposed a novel three-stage crystallization method to synthesize small-crystal and hierarchical SAPO-11 molecular sieve, and prepared the corresponding NiWS supported catalyst for the hydroisomerization of n-hexadecane. The physicochemical properties of the small-crystal and hierarchical SAPO-11 molecular sieve and the NiWS supported catalyst were analyzed via a series of characterization methods. It was found that the crystal size of SAPO-11-S was reduced to 21.8 nm and the particle size was reduced to 70–140 nm. SAPO-11-S was superior to SAPO-11-C in pore properties and acidity. The reason for the increase of the number of medium-strong B acid sites in SAPO-11-S was investigated by 29 Si MAS NMR characterization, and the formation mechanism of SAPO-11-S was proposed by tracking and analyzing the crystallization process of SAPO-11-S. The decrease of crystal size of SAPO-11 molecular sieve effectively improved the sulfidation degree of active metals and the dispersion degree of the active phase of the catalyst, and promoted more active phases to form “type II active phase”. Compared with NiW/SAPO-11-C, NiW/SAPO-11-S showed higher catalytic activity and isomerization selectivity, and the maximum i-hexadecane yield of NiW/SAPO-11-S was 44.77% higher than that of NiW/SAPO-11-C.
研究领域:
催化
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化学工程
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材料科学
✓ 已验证
DOI
高影响因子
Materials
·
2022
·Vol. 15
·期 10
·3708
·
IF 3.748
Luxi Yang,Linchuan Dai,Lu Ye,Rui Yang,Yangcheng Lu
In this study, a strategy based on microfluidic method is developed toward a facile fabrication of phase change material microcapsules with uniform and controllable particle size as well as high encapsulation ratio and thermal stability. N-hexadecane, as a phase change material, was successfully encapsulated by a hybrid shell of poly (methyl methacrylate) and polyurea. The fabrication process includes the following three steps: (1) Formation of oil-in-water droplets with uniform micron size in the microfluidic chip; (2) formation of the first polyurea shell to encapsulate droplets by fast interfacial polymerization when the droplets pass through the coiled transport microchannel; and (3) completion of free radical polymerization of methyl methacrylate inside the microspheres by heating to form the hybrid microcapsule shell. The average size, encapsulation ratio, and phase change enthalpy of microcapsules changed by varying the flow rate of the dispersion phase and raw material composition. The highest melting enthalpy of 222.6 J g−1and encapsulation ratio of 94.5% of the microcapsule were obtained when the flow rates of the continuous and dispersion fluids were 600 μL min−1and 24 μL min−1, respectively. It is shown that the phase change material microcapsules were stable after 50 heating/cooling cycles.Keywords:phase change materials;microencapsulation;microfluidics;thermal energy storage
研究领域:
材料科学
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热能工程
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2024
·
IF 6.7
Xiaojun Dai,Yan Cheng,Tingting Liu,Lingjuan Mao
The application of non-noble metal supported catalysts in the hydroisomerization of long-chain n-alkanes is a novel field, and there is currently not any research available on the deactivation process of these catalysts. We investigated into the deactivation mechanism of NiWS/SAPO-11 catalyst in the hydroisomerization of n-hexadecane in this work for the first time. Specifically, coke deposition behavior and active phase migration were investigated. The reduction of catalytic efficiency of the catalyst was partially aided by the decrease in specific surface area, pore volume, and acid density. From the perspective of the active phase, the clusters of NiWS active phase migrated as the reaction time increased, mostly resulting in an increase in both the stacking number and the length of active phase slabs. The migration of active phase increased the distance between active phase clusters and metal sites, and decreased the utilization ratio of active metal atoms. From the perspective of coke deposition, the coke formed on the catalyst includes soft coke and hard coke. The formation and evolution of coke on the catalyst were investigated. The soft coke (aliphatic compounds) progressively transformed into hard coke (polycyclic aromatic hydrocarbons and graphite-like), and the coke gradually migrated from the external surface of the catalyst to the pore channels as the reaction time increased. It is expected to provide theoretical basis and reference value for the deactivation research and design of non-noble metal supported hydroisomerization catalyst.
研究领域:
催化
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化学工程
·
石油化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2025
·Vol. 13
·期 36
·30599-30617
·
IF 9.5
Xiaojun Dai,Tingting Liu,Lingjuan Mao,Zixuan Lv
In this work, a SAPO-11 molecular sieve was successfully synthesized via an alcohol–water solvent vapor-induced self-assembly conversion method for the first time. Compared with the conventional hydrothermal crystallization method, the alcohol–water solvent vapor-induced self-assembly conversion method used the induction of alcohol–water solvent steam to drive the solid nucleation and crystallization of the SAPO-11 molecular sieve xerogel precursor. SAPO-11 molecular sieves synthesized by the two methods were used as supports and loaded with NiWS active phase to prepare n-hexadecane hydroisomerization catalysts. The effects of the alcohol–water solvent vapor-induced self-assembly conversion method on the physicochemical properties of SAPO-11 were studied. Compared with the conventional hydrothermal crystallization method, the alcohol–water solvent vapor-induced crystallization method improved the pore structure and acidity of SAPO-11, promoted the dispersion of silicon species in SAPO-11, and inhibited Ostwald ripening during the formation of SAPO-11. The crystallization process of SAPO-11 synthesized via the alcohol–water solvent vapor-induced self-assembly conversion method was thoroughly investigated, and the mechanism of the crystallization was discussed. When SAPO-11 synthesized via alcohol–water solvent vapor-induced self-assembly conversion method was used as the support, the MSI of the catalyst weakened and the dispersion and stacking number of the sulfided active phase and the sulfidation degree of the active metals improved. The catalytic results of n-hexadecane hydroisomerization showed that SAPO-11 synthesized via the alcohol–water solvent vapor-induced self-assembly conversion method-based catalyst had higher catalytic activity and target product selectivity than the conventional SAPO-11-based catalyst. The catalytic kinetics of the catalysts were investigated in depth. The results showed that the metal site-acid site synergistic catalytic mechanism of SAPO-11 synthesized using the alcohol–water solvent vapor-induced self-assembly conversion method-based catalyst was better than that of the conventional SAPO-11-based catalyst. When SAPO-11 synthesized via the alcohol–water solvent vapor-induced self-assembly conversion method was used as the support, the hydroisomerization reaction path priority and hydroisomerization depth of the n-hexadecane hydroconversion over the catalyst improved and deactivation resistance was optimized. The approach is expected to provide a new route and reference for the synthesis of high-performance SAPO-11 molecular sieves and the design of high-efficiency hydroisomerization catalysts.
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Xiaojun Dai,Yan Cheng,Meng Si,Qiang Wei,Dongdong Chen,Wenbin Huang,Yasong Zhou
A series of SAPO-11 molecular sieves were synthesized in the concentrated gel system by reducing the water content in the synthesis system. With SAPO-11 molecular sieves as supports, NiW-supported catalysts were prepared for the hydroisomerization of n-hexadecane. SAPO-11 molecular sieves and catalysts were characterized by XRD, SEM, N 2 adsorption–desorption, NH 3 -TPD, Py-IR, HRTEM and XPS. The results showed that reducing the water content in the synthesis system could increase the mesoporous volume of SAPO-11 molecular sieve and improve the acidity of SAPO-11. For the corresponding catalysts, using SAPO-11 synthesized in concentrated gel system as the support weakened the interaction between the active phase and the support, and increased the dispersion and stacking number of the active phase, which effectively improved the catalytic performance of the catalyst. The yield of i-hexadecane of the catalyst NiW/45W-SA corresponding to SAPO-11 synthesized in conventional water content system was 28.14%, while that of the catalyst NiW/5W-SA corresponding to SAPO-11 synthesized in concentrated gel system was 52.24%. According to the distribution of isomers, it is inferred that hydroisomerization of n-hexadecane over NiW/SAPO-11 follows the pore-mouth mechanism.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Frontiers in Chemistry
·
2022
·
IF 5.545
Dai Xiaojun,Cheng Yan,Si Meng,Wei Qiang,Zhou Yasong
The complexation-excessive impregnation modification method, which was original in this study, and the ion-exchange method and the in situ modification method were used to synthesize Ni-modified SAPO-11 molecular sieves. With the Ni-modified SAPO-11 samples as support, the corresponding NiWS-supported catalysts for the hydroisomerization of n-hexadecane were prepared. The effects of Ni-modification on SAPO-11 characteristics and the active phase were studied. The structure, morphology, and acidity of SAPO-11, as well as the interaction between active metals and support, the morphology, dispersibility, and stacking number of the active phase, were all changed by Ni-modification methods. The complexation-excessive impregnation modification method deleted a portion of Al from SAPO-11 molecular sieves while simultaneously integrating Ni into the skeletal structure of the surface layer of SAPO-11 molecular sieves, considerably enhancing the acidity of SAPO-11 molecular sieves. Furthermore, during dealumination, ethylenediaminetetraacetic acid generated more mesoporous structures and increased the mesoporous volume of SAPO-11 molecular sieves. Because the complexation-excessive impregnation modification method increased the amount of Ni in the surface framework of the SAPO-11 molecular sieve, it has weakened the interaction between the active phase and the support, improved the properties of the active phase, and greatly improved the hydroisomerization performance of NiW/NiSAPO-11. The yield of i-hexadecane of NiW/NiSAPO-11 increased by 39.3% when compared to NiW/NiSAPO-11. It presented a realistic approach for increasing the acidity of SAPO-11, reducing the interaction between active metals and support, and improving the active phase stacking problem.
研究领域:
催化
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化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2018
·
IF 1.712
Xiaoqiang Jia,Yun He,Lei Huang,Dawei Jiang,Wenyu Lu
The high-molecular weight polycyclic aromatic hydrocarbons (PAHs) pyrene and typical long chain alkane n -hexadecane are both difficult to degrade. In this study, n -hexadecane and pyrene degrading strain Rhodococcus sp. T1 was isolated from oil contaminated soil. Strain T1 could remove 90.81% n -hexadecane (2 vol%) and 42.79% pyrene (200 mg·L − 1 ) as a single carbon within 5 days, respectively. Comparatively, the degradation of pyrene increased to 60.63%, but the degradation of n -hexadecane decreased to 87.55% when these compounds were mixed. Additionally, identification and analysis of degradation metabolites of Rhodococcus sp. T1 in the above experiments showed that there were significant changes in alanine, methylamine, citric acid and heptadecanoic acid between sole and dual substrate degradation. The optimal conditions for degradation were then determined based on analysis of the pH, salinity, additional nutrient sources and liquid surface activity. Under the optimal conditions of pH 7.0, 35 °C, 0.5% NaCl, 5 mg·L − 1 of yeast extract and 90 mg·L − 1 of surfactant, the degradation increased in single or dual carbon sources. To our knowledge, this is the first study to discuss metabolite changes in Rhodococcus sp. T1 using sole substrate and dual substrate to enhance the long-chain alkanes and PAHs degradation potential.
研究领域:
环境微生物学
·
生物修复
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers in Chemistry
·
2021
·
IF 5.221
Dai Xiaojun,Cheng Yan,Si Meng,Wei Qiang,Zhao Luyuan,Wang Xiaohan,Huang Wenbin,Liu Haoran,Zhou Yasong
SAPO-11 molecular sieves were modified with different Ni contents by the in situ modification method. The Ni-modified SAPO-11 molecular sieves were used as the supports to prepare the corresponding NiW-supported catalysts for the hydroisomerization of n-hexadecane. The Ni-modified SAPO-11 and the corresponding NiW-supported catalysts were characterized by X-ray diffraction, scanning electron microscopy, N2 adsorption–desorption, NH3-temperature-programmed desorption, pyridine adsorbed infrared, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The results showed that Ni in situ modification preserved the crystal structure of SAPO-11; increased the BET specific surface area, mesopore volume, and medium and strong Brønsted acid amount of SAPO-11; and increased the stacking number of the active phase of the catalysts. 3Ni-SAPO-11 possessed the largest BET specific surface area, mesopore volume, and medium and strong Brønsted acid amount. NiW/3Ni-SAPO-11 possessed the highest dispersion of the active phase and the highest sulfidation degree of the active metals. The results of the hydroisomerization of n-hexadecane showed that Ni in situ modification improved the catalytic activity and selectivity of the catalysts for the hydroisomerization of n-hexadecane to varying degrees. Especially, NiW/3Ni-SAPO-11 had the highest catalytic activity and isomer selectivity, and the maximum yield of isomeric hexadecane could reach 71.18%.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2023
·
IF 5.3
Xiaojun Dai,Yan Cheng,Tingting Liu,Lingjuan Mao,Qiang Wei,Yasong Zhou
SAPO-11 molecular sieves with different crystal sizes and particle sizes, especially nanosized small-crystal SAPO-11 molecular sieves, were successfully synthesized, and the corresponding NiWS-supported catalysts were prepared for the hydroisomerization of n-hexadecane. XRD, SEM, N2 adsorption–desorption, Py-IR, and HRTEM were used to analyze the effects of crystal size and particle size of the supports on their physicochemical properties, active phase properties, and catalytic performance of the catalysts. Through reaction evaluation and analysis of isomeric products, the effects of the size change of the support on the hydroisomerization performance of the catalyst and the hydroisomerization depth of n-hexadecane were determined. Through comprehensive analysis of the cracking products, it was determined that secondary cracking occurred when the conversion of n-hexadecane on the NiW/SAPO-11-S catalyst reached about 42.7%, and the secondary isomerization occurred when the conversion of n-hexadecane reached about 80%. The hydroisomerization reaction network of n-hexadecane over the NiWS/SAPO-11 catalyst was studied emphatically, and it was found for the first time that the secondary cracking of n-hexadecane during hydroisomerization followed the C3-β-scission mechanism.
研究领域:
化学工程
·
催化
·
材料科学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Chengdong Guan,Zihan Li,Lijun Zhu,Daohong Xia
Oily wastewater caused by the traditional oil spills and the increment of emerging lipid (such as biodiesel) pollution endangers human and nature seriously. Herein, we conceive a novel β-cyclodextrin-threated interface demulsification structural strategy to assemble superhydrophilic aramid nanofibers (ANFs) membranes for surfactant-stabilized oil-in-water emulsion separation. Aim to modify the monomers, p-Phenylenediamine (PPD) molecules were covered by β-cyclodextrin (β-CD) to form inclusion compounds. Different poly (p-phthaloyl-p-phenylenediamine) with poly-pseudorotaxane structure (β-CD@PPTA) was obtained by low-temperature solution polycondensation by adjusting the proportion of modified monomers. The corresponding β-CD@ANFs membrane was successfully fabricated by non-solvent induced phase separation. The effect of β-CD@PPD monomers on the structure, element content, surface wettability, separation performances and durability of the modified membrane were investigated systematically. The modified membranes had the superhydrophilicity and underwater superoleophobicity characteristics. The flux and oil rejection of membrane both raised with the increased added proportion of β-CD@PPD monomers. The well-designed membrane exhibited tween 60 stabilized N-hexadecane-in-water emulsion permeances over 126.59 ± 5.35 L/m 2 h with separation efficiency above 99.73%. More significantly, the membrane had long-term demulsification performance and ideal purification effect on the separation of biodiesel wastewater, showing forceful prospect in removing lipid oil pollutants from the oil-in-water emulsions. The membrane prepared by poly-pseudorotaxane modification could better serve the development of oil-in-water separation field.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）