Progress in Adsorption-Enhanced Hydrogenation of CO2 on Layered Double Hydroxide (LDH) Derived Catalysts

Xin Fang,Chuang Chen,He Jia,Yingnan Li,Jian Liu,Yisong Wang,Yanli Song,Tao Du,Liying Liu 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.95 No.-

It is acknowledged as a promising strategy to reduce excessive CO2 emissions by catalytic conversion tovalue-added chemicals, in which layered double hydroxide (LDH) derived catalysts play essential roles. Inthe present review, latest progresses were summarized to gain insights on this issue. LDH-derivedcatalysts can be prepared via various methods and possess favorable characteristics of reversibletopotactic transformation for further development. Compared to conventional catalysts, they showspecific advantages in specific surface area, metal element dispersion and active site distribution. Despiteof distinguished LDH-derived catalysts applied in CO2 reduction reactions to methane, methanol,hydrocarbons, etc., state-of-art LDH-derived catalysts consisted of catalyst-adsorbent synergistic systemare recently constructed to employ the surface CO2 adsorption boundary layer to increase the CO2 partialpressure near active sites for hydrogenation. The overall catalytic performance is thus promoteddramatically. Accordingly, the strategy of adsorption-enhanced hydrogenation is expected to facilitatethe industrialization of CO2 hydrogenation and is instructive for catalyst design in future.

Sport impact on the strength of the nanoscale protein tissues under the thermal condition

Xin, Fang,Mengqian, Hou Techno-Press 2022 Advances in nano research Vol.13 No.6

The stability of protein tissues and protein fibers in the human muscle is investigated in the presented paper. The protein fibers are modeled via tube structures embedded in others proteins fibers like the elastic substrate. Physical sport and physical exercise play an important role in the stability of synthesis and strength of the protein tissues. In physical exercise, the temperature of the body increases, and this temperature change impacts the stability of the protein tissues, which is the aim of the current study. The mathematical simulation of the protein tissues is done based on the mechanical sciences, and the protein fibers are modeled via wire structures according to the high-order theory beams. The thermal stress due to the conditions of the sport is applied to the nanoscale protein fibers, then the stability regarding the frequency analysis is investigated. Finally, the impact of temperature change, physical exercise, and small-scale parameters on the stability of the protein tissues are examined in detail.

Tetragonal zirconia based ternary ZnO-ZrO2-MOx solid solution catalysts for highly selective conversion of CO2 to methanol at High reaction temperature

Xin Fang,Yunting Xi,He Jia,Chuang Chen,Yisong Wang,Yanli Song,Tao Du 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.88 No.-

Catalytic conversion of CO2 to methanol has attracted increasing interests as a promising strategy forreducing excessive CO2 emissions. However, the methanol selectivity drops rapidly with elevatedtemperature due to enhanced CO synthesis using conventional catalysts, which hiders its application. Herein, ZnO-ZrO2 solid solution catalysts (SSCs) were prepared with different methods and modified byadding extra metal, i.e., Al, Cr, Fe or Mg. As-prepared SSCs were characterized and tested in reaction. Theresults show that prepared ZnO-ZrO2 SSCs possess similar chemical compositions but different crystals,morphologies and pore systems, among which the C-ZZ synthesized by co-precipitation exhibits theoptimal property. After doping, the basic crystal of tetragonal ZrO2 can be retained and ternary ZnO-ZrO2-MOx SSCs are successfully prepared. There come dramatic improvements in overall catalyticperformance. Specifically, the 3Mg-C-ZZ SSC, at 3.0 MPa and GHSV of~2000 h 1, maintains a considerablemethanol selectivity of 81.5 % even at 320 C. Prepared catalysts present remarkable superiorities toconventional copper-based catalysts especially at high reaction temperatures, which endures thempromising applications in coupling conversion of CO2 to valuable chemicals with the intermedia ofmethanol.

Highly dispersed Cu-ZnO-ZrO2 nanoparticles on hydrotalcite adsorbent as efficient composite catalysts for CO2 hydrogenation to methanol

Xin Fang,Yuhan Men,Fan Wu,Qinghu Zhao,Ranjeet Singh,Penny Xiao,Liying Liu,Tao Du,Paul A. Webley 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.4

CO2 hydrogenation to methanol is attracting specific interest because of its potential economic and environmental benefits in transforming waste CO2 to value-added hydrocarbons. Copper-based catalysts are documented as efficient and widely applied, whereas insufficient catalytic properties of conventional catalysts hinder their application. Herein, catalysts using Mg-Al hydrotalcite (HT) as the carrier of Cu/ZnO/ZrO2 (CZZ) nanoparticles were prepared to exploit special advantages of hydrotalcite on copper dispersion and catalytic performance. The results show that CZZ nanoparticles can be uniformly dispersed on external surfaces of HT, elevating BET surface areas of CZZ-HT samples by at least 2.5 times compared to pure CZZ. The HT carrier also enriches strong basic sites and hence elevates CO2 adsorption capabilities in the range of reaction temperature. Both copper surface area and copper dispersion of CZZ-HT samples are improved dramatically. A catalyst containing 45.1 wt% of CZZ shows 1.1 times higher copper surface area per gram CZZ and 1.6 times higher copper dispersion than the reference CZZ. Subsequent reactions demonstrate the CZZ-HT samples show remarkably promoted turnover frequency (TOF) for methanol synthesis and retain considerable catalyst stability. The typical catalyst prepared in this research, at the reaction temperature of 523 K and pressure of 3.0MPa, presents a 68.2% higher methanol STYCu per gram copper and an 117.0% higher SMeOH/SCO ratio than the commercial catalyst. The support HT plays a crucial role for the enhanced catalytic performance physically and chemically. Thus, the as-prepared CZZ-HT catalyst provides a significant improvement for CO2 utilization.

Metallothionein cDNA Cloning and Metallothionein Expression in Sea Cucumber (Apostichopus japonicus, Slenka) from the WeiHai Coast of China

Xinfang Lv,Xinfang Lv,Xinfang Lv,Zhaoyang Hua 한국해양과학기술원 2018 Ocean science journal Vol.53 No.4

The aims of this work were (1) the identification of the metallothionein (MT) gene cDNA sequence in Apostichopus japonicus and (2) the quantification of MT mRNA expression in the intestine, body wall and respiratory tree of A. japonicas after exposure to cadmium or zinc. Using RT-PCR and RACE-PCR, we cloned the MT complete cDNA sequence of A. japonicus using the RNA extracted from Cadmium-exposed intestines. The 1351 bp MT cDNA consisted of a 126 bp 5’ untranslated region, a 1069 bp 3’ untranslated region, and a 156 bp open reading frame coding for 51 amino acids, including 16 cysteines. The MT sequence of A. japonicus was 47% identical to the sequence of MT from Strongylocentrotus purpuratus. Through real-time quantitative PCR analysis, we found that the MT expression levels were significantly higher when the specimens were exposed to heavy metals, and the response to combined metal ions exposure occurred earlier than that for single metal ion exposure. Additionally, the induction of MT transcription was more responsive to zinc and can be envisaged as a potential biomarker for zinc contamination.

Optimization design for a new large-scale eight-link mechanical press

Xinfang Ge,Chang’an Zhu,Yi Jin 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.4

This study proposes a new, large-scale, eight-link mechanical press that consist of four single degree-of-freedom (DOF) planar eightlinkmechanisms and has a carrying capacity of 2000 tons. Kinematic analysis of a single DOF planar eight-link mechanism is presented. On the basis of kinematic analysis and the required output displacement curve, a single DOF planar eight-link mechanism is synthesizedusing differential evolution algorithm. We propose the use of an improved minimum sum of displacement variance (MSDV) cost functionto minimize the influence of processing error on the same positions of different single DOF planar eight-link mechanisms. The improvedMSDV cost function enables the setting of different weights for different stages with one stroke depending on the importance ofeach stage. Simulation results show that the designed mechanical press is consistent with the requirements, and that the improved MSDVcost function effectively reduces the influence of machining error.

Effects of water vapor, CO_2 and SO_2 on the NO reduction by NH_3 over sulfated CaO

Xinfang Yang,Bo Zhao,Yuqun Zhuo,Changhe Chen,Xuchang Xu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.8

Gas effects on NO reduction by NH_3 over sulfated CaO have been investigated in the presence of O_2 at 700-850℃ . CO_2 and SO_2 have reversible negative effects on the catalytic activity of sulfated CaO. Although H_2O alone has no obvious effect, it can depress the negative effects of CO_2 and SO_2. In the flue gas with CO_2, SO_2 and H_2O coexisting,the sulfated CaO still catalyzed the NO reduction by NH_3. The in situ DRTFTS of H2O adsorption over sulfated CaO indicated that H_2O generated Brønsted acid sites at high temperature, suggesting that CO_2 and SO_2 competed for only the molecularly adsorbed NH_3 over Lewis acid sites with NO, without influencing the ammonia ions adsorbed over Brønsted acid sites. Lewis acid sites shifting to Brønsted acid sites by H_2O adsorption at high temperature may explain the depression of the negative effect on NO reduction by CO_2 and SO_2.

Adsorbate Selectivity of Isoreticular Microporous Metal–Organic Frameworks with Similar Static Pore Dimensions

Liu, Xinfang,Oh, Minhak,Lah, Myoung Soo American Chemical Society 2011 Crystal Growth & Design Vol.11 No.11

<P>Adsorbate selectivity has been investigated using three isoreticular metal–organic frameworks (MOFs) {[ML], <B>1</B> (M = Cu<SUP>2+</SUP>) and <B>2</B> (M = Zn<SUP>2+</SUP>) where L = 5-(pyridin-3-ylethynyl)isophthalate; <B>3</B> (M = Cu<SUP>2+</SUP>) where L = [(pyridin-3-ylmethyl)amino] isophthalate} of similar “static aperture size” but of different framework flexibility, where the MOFs have the same two different types of cagelike pores, cage A and cage B. While cage A of the MOFs with sufficiently large aperture size compared with the dimensions of the adsorbates investigated does not show any adsorbate selectivity, cage B with an approximate size match between the adsorbates and the pore apertures shows size selectivity for the adsorbates. Although the static aperture size of cage B in <B>3</B> is smaller than those in <B>1</B> and <B>2</B>, the order of the “effective aperture sizes” of the cage Bs of the activated MOFs, <B>1a</B>–<B>3a</B>, is <B>2a</B> ≥ <B>3a</B> ≥ <B>1a</B>, which reflects the differing framework flexibility. The size selectivity of the MOFs for N<SUB>2</SUB> and Ar follows the more shape-dependent second minimum dimension (MIN-2) of the adsorbate rather than the widely used kinetic diameter (KD). However, the size selectivity of the MOFs for CO, CO<SUB>2</SUB>, and O<SUB>2</SUB> is neither based on the KD nor on the MIN-2. Not only the aperture size but also the functionality of the aperture-constituting group plays a role in the selective adsorption.</P><P>The adsorbate selectivity of microporous metal−organic frameworks (MOFs) follows the “static aperture size”, not the “effective aperture size”. The size selectivity of the MOFs for N<SUB>2</SUB> and Ar follows the more shape-dependent second minimum dimension (MIN-2) of the adsorbate rather than the widely used kinetic diameter (KD).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cgdefu/2011/cgdefu.2011.11.issue-11/cg200983y/production/images/medium/cg-2011-00983y_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cg200983y'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cg200983y'>ACS Electronic Supporting Info</A></P>

Dispersion behavior and thermal conductivity characteristics of Al2O3–H2O nanofluids

Dongsheng Zhu,Xinfang Li,Nan Wang,Xianju Wang,Jinwei Gao,Hua Li 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Nanofluid is a kind of new engineering material consisting of solid nanoparticles with sizes typically of 1–100 nm suspended in base fluids. In this study, Al2O3–H2O nanofluids were synthesized, their dispersion behaviors and thermal conductivity in water were investigated under different pH values and different sodium dodecylbenzenesulfonate (SDBS) concentration. The sedimentation kinetics was determined by examining the absorbency of particle in solution. The zeta potential and particle size of the particles were measured and the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to calculate attractive and repulsive potentials. The thermal conductivity was measured by a hot disk thermal constants analyser. The results showed that the stability and thermal conductivity enhancements of Al2O3–H2O nanofluids are highly dependent on pH values and different SDBS dispersant concentration of nano-suspensions, with an optimal pH value and SDBS concentration for the best dispersion behavior and the highest thermal conductivity. The absolute value of zeta potential and the absorbency of nano-Al2O3 suspensions with SDBS dispersant are higher at pH 8.0. The calculated DLVO interparticle interaction potentials verified the experimental results of the pH effect on the stability behavior. The Al2O3–H2O nanofluids with an ounce of Al2O3 have noticeably higher thermal conductivity than the base fluid without nanoparticles, for Al2O3 nanoparticles at a weight fraction of 0.0015 (0.15 wt%), thermal conductivity was enhanced by up to 10.1%. Nanofluid is a kind of new engineering material consisting of solid nanoparticles with sizes typically of 1–100 nm suspended in base fluids. In this study, Al2O3–H2O nanofluids were synthesized, their dispersion behaviors and thermal conductivity in water were investigated under different pH values and different sodium dodecylbenzenesulfonate (SDBS) concentration. The sedimentation kinetics was determined by examining the absorbency of particle in solution. The zeta potential and particle size of the particles were measured and the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to calculate attractive and repulsive potentials. The thermal conductivity was measured by a hot disk thermal constants analyser. The results showed that the stability and thermal conductivity enhancements of Al2O3–H2O nanofluids are highly dependent on pH values and different SDBS dispersant concentration of nano-suspensions, with an optimal pH value and SDBS concentration for the best dispersion behavior and the highest thermal conductivity. The absolute value of zeta potential and the absorbency of nano-Al2O3 suspensions with SDBS dispersant are higher at pH 8.0. The calculated DLVO interparticle interaction potentials verified the experimental results of the pH effect on the stability behavior. The Al2O3–H2O nanofluids with an ounce of Al2O3 have noticeably higher thermal conductivity than the base fluid without nanoparticles, for Al2O3 nanoparticles at a weight fraction of 0.0015 (0.15 wt%), thermal conductivity was enhanced by up to 10.1%.

Structural investigations of toluene diisocyanate (TDI) and trimethylolpropane (TMP)-based polyurethane prepolymer

Yong He,Xinfang Zhang,Jie Chang,Huanqin Chen,Xinya Zhang 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5

Polyurethane prepolymer prepared from nonequivalent amounts of toluene diisocyanate (TDI) over trifunctional trimethylolpropane (TMP) was followed by gel permeation chromatography (GPC). Steric hindrance of TMP was considered as the main factor affecting the molar mass distribution, especially in the higher molecular weight region. An optimum reaction condition was the initial NCO/OH ratio of 3 and the reaction temperature of 50 8C. Then polyurethane prepolymer could be purified through the thin film evaporator with excellent properties. A combination of mass spectrometry (MS) and 1H nuclear magnetic resonance (NMR) spectroscopy was employed to identify and confirm the individual compounds presented from GPC analysis.