INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
·
IF 4.326
Lian Duan,Chi Ma,Fengyan Lou,Jiabin Yin,Le Sang,Jisong Zhang
External mass transfer performance of micropacked bed reactors (μPBRs) with Pd/Al2O3/nickel foam catalysts is investigated by the hydrogenation of α-methylstyrene (AMS). The external mass transfer limitation region for AMS hydrogenation can be determined by means of the apparent activation energy and internal effectiveness factor. Parametric studies for external mass transfer are conducted by varying temperatures, operating pressures, liquid viscosities, gas and liquid superficial velocities, and pore diameters of foam packing. The external volumetric mass transfer coefficients [(ka)OV] of μPBRs with the Pd/Al2O3/nickel foam range from 0.06 to 0.71 s–1. An empirical correlation of (ka)OV is developed. Based on the gas–liquid–solid process analysis, the external mass transfer of μPBRs with the Pd/Al2O3/nickel foam is limited by liquid–solid mass transfer under the experimental conditions. Moreover, μPBRs with the Pd/Al2O3/nickel foam exhibit the best energy efficiency in comparison with that of other multiphase reactors.
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高影响因子
Catalysts
·
2022
·Vol. 12
·期 7
·716
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IF 4.501
Xinbo Zhu,Xiqiang Wu,Jin Liu,Jianbin Luo,Zhengda Yang,Ye Jiang,Geng Chen
In this work, soot oxidation was conducted over a series of Mn-X/γ-Al2O3(M = Ce, Co and Cu) binary catalysts in a dielectric barrier discharge reactor. The soot conversion in the plasma–catalytic system was in the order of Mn/γ-Al2O3(57.7%) > Mn-Co/γ-Al2O3(53.9%) > Mn-Ce/γ-Al2O3(51.6%) > Mn-Cu/γ-Al2O3(47.7%) during the 30 min soot oxidation process at 14 W and 150 °C. Meanwhile, the doping of Ce, Co and Cu slightly improved the CO2selectivity of the process by 4.7% to 10.3% compared to soot oxidation over Mn/γ-Al2O3.It is worth to note that the order of CO2selectivity was in the opposite order with soot oxidation rate. The effects of discharge power, oxygen content in the carrier gas and reaction temperature on plasma–catalytic soot oxidation was systematically analyzed. The catalyst characterizations, including N2adsorption–desorption, X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction by H2and temperature-programmed desorption of O2,were conducted to illustrate the reaction mechanisms of plasma–catalytic soot oxidation and reaction pathways.Keywords:plasma–catalysis;soot oxidation;manganese-based oxides;transition metal;binary catalyst
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ACS Applied Nano Materials
·
2022
·
IF 6.14
Yujia Yuan,Zhongliang Huang,Siyuan Hu,Dongren Cai,Guowu Zhan
In the field of catalysis, nanoreactors with spatially restricted effects play a critical role to enhance the production efficiency of a variety of reactions. In this contribution, we used ZIF-67 nanocubes (size of 140 nm) as a template and conformally deposited Al2O3 thin films by the atomic layer deposition (ALD) technique, wherein Pt nanoparticles (Pt NPs) as active sites were loaded on either the inside or outside of the Al2O3 films. Notably, it was found that the water treatment of the nanoreactors was critical to the enhanced catalytic CO oxidation performance with substantially decreased T100 (temperature to achieve 100% conversion). Various characterization results indicated the successful synthesis of yolk–shell structured ZIF-67/Pt@10Al2O3-W catalyst with excellent CO oxidation activity and good long-term stability. In addition, in situ diffuse reflectance infrared Fourier transform spectroscopy was used to explore the catalytic oxidation process, and the results revealed that the reason for the superior CO catalytic activity of the designed nanoreactors was ascribed to the moderate CO surface coverage provided by the Al2O3 films and the activated oxygen species. In summary, this work provides some insights into the preparation of metal–organic framework-based nanoreactors using ALD-assisted methods.
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RSC Advances
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2022
·Vol. 12
·期 21
·13261-13266
·
IF 4.036
Tao Li,Hongjun Kang,Songtao Lu,Wei Qin,Xiaohong Wu
As deep space exploration moves farther and farther away, thermal control coating of the in-orbit spacecraft will suffer a serious vacuum-ultraviolet radiation environment, which seriously threatens the reliability of the spacecraft in orbit. Therefore, it is important to improve the vacuum-ultraviolet resistance performance of the thermal control coating. In this work, the inorganic Al2O3–ZnO–Y2O3 thermal control coating was in situ fabricated on a 6061 aluminum alloy surface by PEO technology, and its vacuum-ultraviolet resistance performance was investigated. The results show that the Al2O3–ZnO–Y2O3 thermal control coating has a good resistance performance to vacuum-ultraviolet radiation, which is mainly because the large extinction coefficients of the ZnO and Y2O3 materials in the ultraviolet band are conducive to improving the ultraviolet resistance performance. Furthermore, the life prediction model of the Al2O3–ZnO–Y2O3 thermal control coating shows that its Δαs value first slightly increases and then tends to be stable with the increase of ultraviolet irradiation time from 0 ESH to 25 000 ESH, and the maximum variation of Δαs is about 0.0536. This work provides a material basis and technical support for the thermal control system of spacecraft with long life and high reliability.
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PubMed
高影响因子
Molecular Catalysis
·
2022
·
IF 5.089
Zhiquan Yu,Yan Li,Yunlong Yao,Yao Wang,Ying-Ya Liu,Zhichao Sun,Chuan Shi,Wei Wang,Anjie Wang
A bifunctional Ni 3 P/γ-Al 2 O 3 catalyst with both metal site and Lewis acid site was prepared by an electroless plating method, and applied in hydrogenative ring-rearrangement of furfural to cyclopentanone. The obtained catalyst was characterized by XRD, XPS, XAS, N 2 adsorption-desorption, ICP, TEM, CO chemisorption, NH 3 -TPD and Py-FTIR. The ultrafine Ni 3 P nanoparticles (∼3.8 nm) were highly dispersed in the catalyst. The exclusive Lewis acidity of Ni 3 P/γ-Al 2 O 3 was beneficial for the aqueous-phase hydrogenative ring-rearrangement. The effects of DP time, reaction parameters (temperature, H 2 pressure, solvent composition, and reaction time) on the catalytic performance were investigated. The yield of cyclopentanone was 74.6% at furfural conversion of 99.9% at 180 °C in 1 h over Ni 3 P/γ-Al 2 O 3 catalyst using pure water as the solvent. Moreover, the kinetics of hydrogenative ring-rearrangement of furfural catalyzed by Ni 3 P/γ-Al 2 O 3 was investigated.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Yixi Wang,Wenqing Xu,Chaoqun Li,Yang Yang,Zanbu Geng,Tingyu Zhu
Gaseous ammonia (NH 3 ), especially that emitted from selective catalytic reduction with NH 3 (NH 3 –SCR) units in the atmosphere is potentially harmful to both human health and the environment. The noble metal catalytic oxidation technology placed behind the SCR unit has been considered to be a promising method for decreasing NH 3 slip. In this study, we prepared Ir/Al 2 O 3 catalysts using two different crystal structures of Al 2 O 3 (α–Al 2 O 3 or γ–Al 2 O 3 ) as supported by an impregnation method and evaluated the performance of the selective catalytic oxidation of NH 3 (NH 3 –SCO). We found that the Ir/γ–Al 2 O 3 catalyst performed better than the Ir/α–Al 2 O 3 catalysts, with 99% of NH 3 converted at 260 °C. The X–ray absorption fine structure revealed that the active species on the Ir/Al 2 O 3 catalysts are mainly oxidized IrO 2 . High–angle annular dark–field images of aberration–corrected scanning transmission electron microscopy revealed that IrO 2 species over 1 nm in diameter are beneficial for activity. In situ diffuse reflectance for infrared Fourier transform spectroscopy studies suggested that the differences in NH 3 –SCO activity were caused by the activity of reactive oxygen species, and the formation of –NH 2 may be the decisive step of the NH 3 oxidation reaction.
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高影响因子
Crystals
·
2022
·Vol. 12
·期 3
·318
·
IF 2.67
Ze Li,Jie-Ying Jing,Zhi-Qiang Qie,Wen-Ying Li
Jet fuel rich in hydroaromatics and cycloalkanes could be derived from direct coal liquefaction oil via the hydrogenation saturation process. Developing an efficient catalyst to transform naphthalene hydrocarbons to hydroaromatics and cycloalkanes with high selectivity plays a significant role in realizing the above hydrogenation saturation process. In this work, Ni2P/Al2O3catalysts were prepared at different reduction temperatures via the thermal decomposition of hypophosphite. We investigated the influence of reduction temperature and the results showed that reduction temperature had an important impact on the properties of Ni2P/Al2O3catalysts. When the reduction temperature was 400 °C, the Ni2P particle size of the Ni2P/Al2O3catalyst was 3.8 nm and its specific surface area was 170 m2/g. Furthermore, the Ni2P/Al2O3catalyst reduced at 400 °C obtained 98% naphthalene conversion and 98% decalin selectivity. The superior catalytic activity was attributed to the smaller Ni2P particle size, higher specific surface area and suitable acidity, which enhanced the adsorption of naphthalene on Ni2P/Al2O3catalyst.Keywords:nickel phosphide;reduction temperature;naphthalene hydrogenation;thermal decomposition of hypophosphite
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高影响因子
Atmosphere
·
2022
·Vol. 13
·期 2
·333
·
IF 3.11
Chao Wang,Lingdong Kong,Shengyan Jin,Lianghai Xia,Jie Tan,Yuwen Wang
Soot and aged soot are often found to be mixed with atmospheric particles, which inevitably affect various atmospheric heterogeneous reactions and secondary aerosol formation. Previous studies have investigated the heterogeneous reaction of NO2with different types of soot, but there are few studies on the heterogeneous reaction of NO2with mixtures containing diesel soot (DS) or aged DS and mineral dust particles. In this study, the effects of DS and aged DS on the heterogeneous reaction of NO2on the surface of γ-Al2O3were investigated via in-situ diffuse reflectance infrared Fourier transform spectrometry (DRIFTS). The results showed that the DS or DS n-hexane extract significantly inhibited the formation of nitrate on γ-Al2O3particles and promoted the formation of nitrite. At 58% RH, with the increase of DS or DS n-hexane extract loading amount, the effect of DS or DS n-hexane extract on the formation of nitrate changed from promotion to inhibition, but DS or DS n-hexane extract always promoted the formation of nitrite. The results also showed that light was conducive to the formation of nitrate on the DS-γ-Al2O3or DS-n-hexane extract-γ-Al2O3particles. Furthermore, the influence of soot aging on the heterogeneous reaction of NO2was investigated under light and no light. In the dark, O3-aged DS-γ-Al2O3or O3-aged DS-n-hexane extract-γ-Al2O3firstly inhibited the formation of nitrate on the mixed particles and then promoted it, while the effect of aged DS on nitrite formation was complex. Under light, the O3-aged DS-γ-Al2O3firstly promoted the formation of nitrate on the mixed particles and then inhibited it, while the O3-aged DS-n-hexane extract-γ-Al2O3promoted the formation of nitrate on the mixed particles. Our results further showed that the production of nitrate on the O3-aged particles under light or no light was greater than that of the UV-nitrate-aged particles. This study is helpful to deeply understand the atmospheric chemical behavior of soot and the heterogeneous conversion of atmospheric NO2.Keywords:soot;NO2;heterogeneous reaction;aged soot;γ-Al2O3
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Weichao Wang,Gu Liu,Liuying Wang,Chaoqun Ge,Long Wang,Bin Wang,Jie Huang
The advancement of absorption materials and coating preparation technology is crucial to address the challenges posed by electromagnetic interference and pollution in high-temperature extreme environments. Here, by using a granulation and plasma spraying strategy, we successfully fabricated a series of La 0.8 Sr 0.2 MnO 3 /Al 2 O 3 –13%TiO 2 (LSMO/AT13) high-temperature microwave absorption coatings that have excellent dielectric properties and extremely thermal stability. The results showed that the LSMO/AT13 coatings exhibited remarkable oxidation resistance , withstanding high-temperature aerobic environments of up to 1000 °C. Based on the temperature-dependent permittivity of the coatings, the establishment process of polarization and the transformation of loss mechanism were observed and explained. With the increase of temperature, the main dielectric loss mechanism of the coatings transitions from polarization loss to conductive loss. Thanks to the coordinated effects of impedance and loss, the coatings are capable of effectively absorbing microwave over a wide temperature range. When the LSMO content was 30 wt% and the thickness was 1.9 mm, the effective bandwidth ranged from 1.7 GHz to 2.4 GHz at temperatures below 773 K. This study demonstrates the promising application of LSMO/AT13 microwave absorption coatings for ultra-high temperature environment, and provides a reference for the design and optimization of high-temperature microwave absorption coatings.
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SURFACE & COATINGS TECHNOLOGY
·
2021
·
IF 4.158
Lei Dai,Tingting Wang,Boxuan Jin,Na Liu,Yifei Niu,Wenhao Meng,Ziming Gao,Xianwen Wu,Ling Wang,Zhangxing He
Zinc is a widely used anode material for zinc-ion batteries. However, the problems of dendrites and side reactions faced by the metal zinc anode limit its cycle stability and service life. Surface modification is a simple and effective strategy for preparing high-performance anodes. Here, we used a simple method to coat the γ-Al 2 O 3 on surface of metal zinc as an artificial protective layer for the anode/electrolyte. γ-Al 2 O 3 coating can guide the uniform deposition of zinc ions . The coating has good hydrophilicity, which is conducive to accelerate ion transmission. In addition, the importance of controlling the thickness of protective layer on surface of zinc metal anode to obtain good electrochemical performance is emphasized. The appropriate thickness of Al 2 O 3 coating ensures the rapid migration of zinc ions and improves the uniformity of zinc plating/stripping, which is conducive to more uniform zinc nucleation and high-quality deposition. Therefore, the discharge capacity of Zn@Al 2 O 3 -15 full cell at a current density of 0.3 A g −1 is 174.3 mAh g −1 , which is much higher than that of bare zinc cell (71.8 mAh g −1 ). This work has certain reference significance for the development of anode coating strategies in zinc-ion batteries.
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高影响因子
Journal of Water Process Engineering
·
2023
·
IF 7
Longxiang Xia,Jing Shen,Dengfeng Wu
Herein, Al 2 O 3 supported ultra-small Mn-CeOx nanoparticles (Mn-CeOx/Al 2 O 3 ) are prepared by a facile impregnation method for removal of phenolic compounds via catalytic ozonation . Mn and Ce species are in the form of polyvalent oxide nanoparticles with an average size of 0.9 nm. The removal efficiency of total organic carbon for phenol-containing model wastewater by Mn-CeOx/Al 2 O 3 shows a volcano relationship by changing the mass ratio of Mn and Ce, and reaches up to the peak value when the mass ratio is 5:5. The cycle stability tests suggest the removal efficiency of Mn-CeOx/Al 2 O 3 could maintain at 90.16 % after 5 circles. The enhanced performance should be attributed to the optimized magnetism and accelerated charge transfer by composition regulation. The magnetic strength changing affects the adsorption mode of O 3 , while the redox cycle of Mn(IV)/Mn(III) and Ce(IV)/Ce(III) could enhance the activation of O 3 to produce more ·OH and 1 O 2 for the organic molecules mineralization.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Yuxi Gao,Baofang Jin,Zhenyu Xi,Zhenguo Li,Xiaodong Wu,Rui Ran,Zhichun Si,Duan Weng
Silver-based catalysts are promising candidates for soot oxidation because of their good catalytic performances and low costs compared with platinum catalysts. NO2 acts as a strong agent for the oxidation of soot over Pt/Al2O3. However, an abnormal inhibition effect of NOx was observed over the Ag/Al2O3 catalyst during the processes of soot temperature-programmed oxidation and transient reaction analysis. The formation of silver nitrates was confirmed by temperature-programmed decomposition of NOx, ultraviolet–visible spectroscopy, and temperature-programmed reduction with H2. The intrinsic reactivity of silver nitrate was found to be much lower than that of metallic silver in ″loose″ and ″tight″ contacts between soot and catalyst. Moreover, the formed silver nitrate was relatively thermally stable, with the decomposition completed at around 450 °C. At higher temperatures, the catalyst recovered and the nitrate poisoning effect no longer worked.
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