Soft Matter
·
2015
·Vol. 11
·期 14
·2885-2892
·
IF 4.029
Dashuang Fan,Peizhu Zheng,Yuanming Ma,Tianxiang Yin,Jihua Zhao,Weiguo Shen
The concentration-dependent enthalpies of mixing for water/sodium bis(2-ethylhexyl)-sulfosuccinate (AOT)/n-alkane microemulsions with different water contents ω0 and chain lengths n of n-alkane were determined by isothermal titration microcalorimetry (ITC) and flow-mixing microcalorimetry at 298.15 K and used to calculate the interaction enthalpies (−ΔHC) between the droplets. It was found that −ΔHC increased with ω0, and changed from negative to positive at about ω0 = 10. The investigation of the dependence of −ΔHC on n revealed that the values of −ΔHC were negative and had a minimum for ω0 = 5; while they were positive and had a maximum for ω0 = 15. These phenomena were discussed based on the competition of the overlapping contribution of the surfactant tails between two neighbouring droplets and the penetration contribution of the solvent molecules into the surfactant tails. These results indicated the important role of entropy in the stability of the microemulsion systems.
研究领域:
化学
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2012
·
IF 1.693
Xianjie Gong,Yongsheng Guo,Juan Xiao,Yuzhong Yang,Wenjun Fang
Densities, viscosities, and refractive indices are investigated for binary mixtures of 1,2,3,4-tetrahydronaphthalene with several n-alkanes, namely, octane, nonane, and decane, at different temperatures (293.15 K, 298.15 K, 303.15 K, and 313.15 K) and atmospheric pressure. The values of density (ρ) of the compounds were used to compute excess molar volume (VmE) of the solution. The refractive indices of these binary systems were also determined over the whole concentration range at 293.15 K and 303.15 K.
研究领域:
物理化学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Guanhua Xing,Siyang Liu,Qingxin Guan,Wei Li
This paper focused on the isomerization and cracking of n -alkanes to synthesize bio-jet fuel. A series of SAPO-11 supports with different Si/Al molar ratio (0.2, 0.4, 0.6) were prepared, characterized, and evaluated by the hydroisomerization on hydrodeoxygenation product of castor oil. As a result, a Ni-Mo/SAPO-11(0.4) catalyst with hollow tubular structure and moderate acidic strength exhibited optimum conversion (97.2%) and jet fuel selectivity (81.6%) in the reaction. Subsequently, Ni-Mo/SAPO-11(0.4) was selected to carry out further experiments on studying the hydroisomerization and hydrocracking of long chain n -alkanes. The results show that increasing temperature may promote hydroisomerization and hydrocracking. Temperature is more favorable for the reaction with the length of the carbon chain decreasing, no matter conversion, hydrocracking degree or isomerization tendency. The product selectivity of different n -alkanes is associated with the carbon number. In reaction to n -C 18 , Ni-Mo/SAPO(0.4) surpassed the other two catalysts in the conversion and i/n ratio at 623 K which is the optimum temperature.
研究领域:
催化化学
·
能源科学
✓ 已验证
DOI
高影响因子
JOURNAL OF POROUS MATERIALS
·
2015
·Vol. 22
·期 5
·1195-1203
·
IF 1.108
Wu Qigang,Xu Rong,Li Jing,Zhang Qi,Zhong Jing,Huang Weiqiu,Gu Xuehong
The compact ZIF-69 membranes have been prepared by seeded growth method for the recovery of gasoline vapor which is a major challenge in the petrochemical industry. The membrane performances for separating N 2 /n-alkane mixtures at various operating conditions (e.g. trans-membrane pressure difference, operating temperature, feed concentration, and stage cut) were systematically investigated. The highest separation factor was 2.60 with the corresponding permeance of 5.02 × 10 −8 mol/(m 2 s Pa) for the N 2 /n-C 6 H 14 model mixtures. Moreover, the effects of n-alkane components (n-C 5 H 12 , n-C 6 H 14 , and n-C 7 H 16 ) on the separation performances were studied, and the separation factors followed α (N 2 /n-C 7 H 16 ) > α (N 2 /n-C 6 H 14 ) > α (N 2 /n-C 5 H 12 ), due to the different adsorption capacities of n-alkanes on ZIF-69 materials. The present work demonstrates that the ZIF-69 membrane is a highly promising candidate for the application in gasoline vapor recovery.
研究领域:
材料科学
·
化学工程
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Optoelectronics
·
2017
·Vol. 10
·期 2
·132-137
·
IF 0
Jiang Chen,Zhan Honglei,Zhao Kun,Fu Cheng
The terahertz (THz) time-domain spectroscopy technique was used to characterize the cooling process of solid n -alkanes. The THz waveforms of n -octadecane, n -nonadecane, n -eicosane, n -heneicosane, n -docosane, and n -pentacosane were obtained with the cooling time using the aforementioned noncontact optical method. The peak values of the THz signal were found to be related to the cooling temperature of n -alkanes. The THz wave was sensitive to the size and structure of particles in the liquid; therefore, the crystallization process of n -alkanes was monitored. An empirical equation based on signal attenuation was proposed to quantitatively distinguish the content change of structural order in the samples. Results present a new noncontact optical approach for characterizing wax crystallization via THz time-domain spectroscopy.
研究领域:
化学
·
物理学
✓ 已验证
DOI
TALANTA
·
2018
·
IF 4.244
Wenjin Wang,Zhi Li,Shuaihua Zhang,Xiumin Yang,Chun Wang,Zhi Wang
A novel nanoporous carbon (NPC) was constructed by utilizing the porous aromatic framework-6 (PAF-6) as both the template and carbon source along with KOH as a chemical activator. The newly-synthesized PAF-6 derived nanoporous carbon (PAF-6-NPC) was then employed as a solid-phase microextraction (SPME) fiber coating. Coupled with gas chromatography-flame ionization detection, the PAF-6-NPC fiber-based SPME method exhibited large enhancement factors, low limits of detection, good linearity and acceptable repeatability for the determination of some n -alkanes in various water and soil samples. The method recoveries for the n -alkanes were in the range of 89.5–102.9% for water and 86.0–104.5% for soil samples, respectively. The PAF-6-NPC coated fiber showed no obvious decrease of the extraction efficiency for the analytes after 100 replicate extractions. The PAF-6-NPC fiber-based SPME method was successfully applied for the determination of n -alkanes in water and soil samples.
研究领域:
分析化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Small Methods
·
2019
·Vol. 3
·期 5
·1800510
·
IF 0
Dongxu Wang,Jiancong Liu,Xusheng Cheng,Xin Kang,Aiping Wu,Chungui Tian,Honggang Fu
The significant increase of catalytic efficiency while remaining low Pt usage is constantly pursued, but remains a challenge. Here, a “vacuum-assisted” (VA) process toward Pt clusters dispersed on SAPO-11 (S-11) is shown for a high-effective hydroisomerization of n -C 16 . The VA can make effective trapping of the Pt precursor on S-11 due to intensive capillary action, being conductive to stabilize and disperse Pt cluster (≈1 nm) on S-11 (V-Pt/S-11) for promoting synergy of Pt sites and acid sites on S-11. The test indicates excellent catalytic activity and stability of trace Pt clusters (0.15 wt%, even lower, 0.035 wt%) on S-11 (≈94.4% isomer selectivity at 94.3% conversion), much superior to I-0.15 wt% Pt/S-11 from traditional impregnation routes (≈88% selectivity at 90% conversion) and ever reported catalysts. The V-Pt/S-11 is also superior for the hydroisomerization of catalytic diesel oil with a decrease of freezing point up to 40 °C after hydroisomerization. The superior performance is attributed to the exposure of high acid density due to little coverage of Pt cluster on S-11, high dispersion of Pt leading to form more metal–acid bifunctional sites, and enhanced (de)hydrogenation ability of Pt clusters. All of them can promote the effective synergy of metal sites (Pt) and acid sites.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
THERMOCHIMICA ACTA
·
2015
·
IF 2.184
Xiaolin Qiu,Lixin Lu,Ju Wang,Guoyi Tang,Guolin Song
Microencapsulation of n -octadecane or paraffin with poly(lauryl methacrylate) (PLMA) shell was performed by a suspension-like polymerization. The polymer shell was crosslinked by pentaerythritol tetraacrylate (PETRA). The surface morphologies of microcapsules were investigated by scanning electron microscopy (SEM). Phase change properties, thermal reliabilities and thermal stabilities of microcapsules were determined by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The n -octadecane microcapsule exhibits higher melting enthalpy (118.0 J g −1 ) and crystallization enthalpy (108.3 J g −1 ) compared with the paraffin microcapsule. The thermal resistant temperatures were enhanced by more than 25 °C when n -alkanes were microencapsulated by PLMA. The PCM contents of microcapsules decreased by less than 4 wt% and 6 wt% after 500 and 1000 thermal cycles, respectively. Heat-up experiments indicated that microcapsule-treated foams exhibited upgraded thermal regulation capacities. Consequently, microencapsulated n -octadecane or paraffin with PLMA as shell possesses good potentials for heat storage and thermal regulation.
研究领域:
材料科学
·
热能工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
·
2023
·
IF 13.1
Bing Ma,Jingqing Tian,Xueling Lang,Shutao Lei,Bolong Li,Chen Zhao
Ultra-long n -alkanes are highly valuable in both scientific research and as major constituents of specialty high-melting-point waxes. Unlike conventional methods (e.g., Fischer–Tropsch (FT), ethylene oligomerization, and polyethylene cracking) typically resulting in wide n -alkane distributions, the elaborate design strategy presented herein allows the direct synthesis of pure, long n -alkanes using a modular splicing method with acetone, furfural, and fatty acid anhydrides or acyl chlorides as bio-blocks. The herein approach is based on a simple four-step catalytic reaction scheme involving C–C chain elongation and C–O bond activation. The synthesized pure n -alkanes had a carbon chain length as high as C 49 (total yield of 49%). The synthesis approach also allows to selectively prepare n -alkanes with even and odd carbon numbers ranging from C 15 to C 49 . This process represents a great breakthrough in the synthesis of long-chain pure n -alkanes, surpassing the carbon number limitations reported in previous methodologies.
研究领域:
有机化学
·
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2020
·
IF 5.578
Lei Chen,Guangci Li,Mingjie Zhang,Da Wang,Shuangju Li,Chuanhui Zhang,Xuebing Li,Keng H. Chung
Catalytic deoxygenation of fatty acids to alkanes is an ideal route to produce biodiesel with high heating value . However, traditional transition-metal sulfide and noble metal catalysts are sulfide-contaminated, high cost, or easily poisoned. To overcome the above issues, this work developed a non-noble and sulfide-free reduced transition-metal composite Ni x Nb y O z , which was effective to selectively hydrogenate stearic acid , a typical fatty acid model compound, to diesel-range alkanes. By using a simple slurry method, reduced Ni x Nb y O z catalysts have been successfully prepared with an outstanding catalytic performance. The results showed that catalyst Ni 0.5 Nb 0.5 O z effectively converted stearic acid to n -alkanes with nearly 100% conversion and >99% n -alkanes selectivity at mild conditions (513 K and 3.5 MPa of H 2 pressure). Appropriate Nb species improved the dispersion of Ni species, which may supply more hydrogenation active sites. Two possible reaction routes of stearic acid were proposed, and the hydrogenolysis of stearyl stearate was confirmed as the rate-determining step based on the kinetics experiments. Because of moderate acidity of Nb species, the ratio of C 17 /C 18 alkane was not markedly affected by reaction conditions when the conversion of stearic acid was higher than 99%. Moreover, catalyst Ni 0.5 Nb 0.5 O z showed a high recycle ability and compatibility for other long-chain fatty acids, demonstrating that catalyst Ni 0.5 Nb 0.5 O z is a promising green catalyst for producing biodiesel from fatty acids.
研究领域:
催化化学
·
能源化学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Jinhui Song,Tianfu Zhang,Mengjiao Xing,Junfeng Zhou,Lu Tang,Jiaxin Xie,Zimin Peng,Wenyao Gu,Jianyu Tang,Suyao Liu,Tong Chang,Yi Liu,Yiwen Fang
With the potential application of biomass-derived feedstock upgradation to sustainable aviation fuels, it is essential to enhance the hydroisomerization performance of ZSM-22 zeolite while improving its resistance to residual oxygen-containing compounds. As the defect sites in the ZSM-22 zeolite, the abundant Si-OH groups are closely related to the catalytic performance and stability, serving as the main attack sites for the generated water. In this work, liquid-mediated defect-healing treatment is performed to heal Si-OH to Si-O-Si, leading to the enhancement of the crystallinity and pore connectivity without affecting the Si/Al, micropore volume, and morphology and preventing the micropores blockage and dealumination caused by conventional silylation and silication procedures. The outcome of the declined Si-OH groups is the reduction of the Lewis acid site without altering the Brønsted acidity. In the n-dodecane hydroisomerization, the catalyst obtained by the liquid-mediated defect-healing treatment route shows an increased conversion and isomer yield compared to the parent and healed catalysts prepared by other healing methods. This is mainly due to enhanced confinement of the micropore void, resulting in decreased apparent activation energy and reduced yield to multi-branched isomers prone to cracking. Furthermore, the healed catalyst exhibits improved resistance and structure stability in the hydroisomerization of feedstocks containing butanol. The work provides a prospective application of ZSM-22 zeolite in the hydroisomerization for complex and severe reactants through the essential Si-OH healing method.
研究领域:
催化化学
·
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2011
·
IF 2.089
Lingling Zhang,Yongsheng Guo,Juan Xiao,Xianjie Gong,Wenjun Fang
Densities and viscosities were determined over the whole composition range for the binary mixtures of exo-tetrahydrodicyclopentadiene with n-nonane, n-dodecane, or n-tridecane at different temperatures (293.15, 298.15, 303.15, and 313.15) K and atmospheric pressure. The excess molar volumes VmE for the mixtures were calculated from the experimental data. The refractive index and surface tension of the systems were also measured for temperatures of (293.15 and 303.15) K.
研究领域:
物理化学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）