Catalysis Science & Technology
·
2020
·Vol. 10
·期 17
·5829-5839
·
IF 5.721
Hanlin Chen,Gaoling Wei,Xiaoliang Liang,Peng Liu,Yunfei Xi,Jianxi Zhu
Thermal catalytic oxidation is regarded as an effective technique to eliminate volatile organic compounds (VOCs), whereby perovskite-type oxides have been reported as low-cost and highly efficient transition metal catalysts. In this study, we employ two facile modification methods, i.e., Ca substitution and citric acid etching, to further improve the catalytic activity of LaCoO3 perovskite for toluene oxidation. The Ca-substituted LaCoO3 (La0.9Ca0.1CoO3) and citric acid-etched LaCoO3 (LaCoO3–CA) show T90 values at 220 and 215 °C, respectively, which are substantially lower than that of pristine LaCoO3 (305 °C). When LaCoO3 is modified by both Ca substitution and citric acid etching, i.e., La0.9Ca0.1CoO3–CA, the T90 further decreases to 202 °C, even lower than that of the commercial catalyst 0.5 wt% Pt/Al2O3 (208 °C). In terms of specific reaction rate at 200 °C, the activity of the above catalysts is also enhanced as follows: LaCoO3 (0.14 μmol s−1 m−2) < La0.9Ca0.1CoO3 (0.31 μmol s−1 m−2) < LaCoO3–CA (0.47 μmol s−1 m−2) < La0.9Ca0.1CoO3–CA (0.63 μmol s−1 m−2). The effects of Ca substitution and citric acid etching are discussed in light of the crystal structure, morphology, and lattice defects. On the one hand, Ca substitution and citric acid etching increase the specific surface area and pore volume, which facilitate the contact between toluene and active sites. On the other hand, these methods produce more oxygen vacancies, enhance the reducibility, and facilitate the adsorption of oxygen. The above merits result in the increase in the specific reaction rate. The modified catalysts show a better water resistance than pristine LaCoO3. As verified in the H2O-TPD characterization, this phenomenon is ascribed to the generation of surface hydroxyl groups, which are beneficial for toluene oxidation at high humidity.
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JOURNAL OF MOLECULAR LIQUIDS
·
2019
·
IF 4.561
Hengxin Fang,Zhixu Tang,Xinjuan Liu,Yongli Huang,Chang Q. Sun
It has been a long pursuit to discriminate the ionic roles of mono- and di-valent salt solutions in modulating the hydrogen bonding network and solution properties. We attended this issue by examining the effect of concentrated YX 2 (Y Mg, Ca, Sr; X Cl, Br) solvation on O:H O bonds transition from the mode of ordinary water to hydration in terms of the number fraction f YX2 ( C ) and the segmental O:H O bond phonon stiffness shift Δω(C) with C being the solute concentration. The invariant df Y ( C ) / dC at C ≤ <0.05 suggests that the small Y 2+ forms a constantly-sized hydration droplet with weak responding to interference of other ions because its hydrating H 2 O dipoles screen mostly its electric field. However, the number inadequacy of the highly-ordered hydrating H 2 O dipoles partially screens the large X − . The X − ↔ X − electrostatic repulsion weakens its electric field. The concentration-trend consistency of the f YX2 ( C ), the solution conductivity σ YX2 ( C ), and surface stress (contact angle) θ YX2 ( C ) for YX 2 solutions clarifies their common origin of ionic polarization. However, the Jones–Dale notion disobedience of the viscosity η YX2 ( C ) suggests the dominance of the inter-ion repulsion.
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THERMOCHIMICA ACTA
·
2017
·
IF 2.236
Mei Wang,Xianghai Song,Jianchun Jiang,Jianling Xia,Shouhai Li,Mei Li
Hydroxyl and nitrogen rich groups-containing tung-oil-based Ca/Zn (Ca-HTMA-1, Zn-HTMA-1, Ca-HTMA-2 and Zn-HTMA-2) and polyol thermal stabilizers (HTMA-1 and HTMA-2) were successfully synthesized from tung-maleic anhydride (TMA). The thermal stability tests show that CaSt 2 /Zn-HTMA-2/HTMA-2 displays the best thermal stability for poly(vinyl chloride) (PVC). The superior performance is attributed to the synergistic effect of CaSt 2 , Zn-HTMA-2 and HTMA-2, which is originated from the simultaneous introduction of hydroxyl and nitrogen rich groups into the Zn-HTMA-2 and HTMA-2 structures. The nitrogen rich groups can absorb the hydrogen chloride released during the PVC degradation process, which helps to inhibit the “autocatalytic effect” and lead to better long term thermal stability. Besides, hydroxyl groups can form stable chelates with ZnCl 2 to avoid “zinc-burning” during the later PVC degradation. Besides the better stabilization performance, CaSt 2 /Zn-HTMA-2/HTMA-2 also displays comparable plasticization performance for PVC compared with other stabilizers. A possible stabilizing mechanism of PVC/CaSt 2 /Zn-HTMA-2/HTMA-2 system was presented.
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BIOMACROMOLECULES
·
2016
·
IF 5.583
Jing-Xiao Hu,Jia-Bing Ran,Si Chen,Pei Jiang,Xin-Yu Shen,Hua Tong
By in situ combining the dual cross-linking matrices of the carboxylated agarose (CA) and the silk fibroin (SF) with the hydroxyapatite (HA) crystals, the CA-SF/HA composites with optimal physicochemical and biological properties were obtained, which were designed to meet the clinical needs of load-bearing bone repair. With the synergistic modulation of the dual organic matrices, the HA nanoparticles presented sheet and rod morphologies due to the preferred orientation, which successfully simulated the biomineralization in nature. The chemical reactivity of the native agarose (NA) was significantly enhanced via carboxylation, and the CA exhibited higher thermal stability than the NA. In the presence of SF, the composites showed optimal mechanical properties that could meet the standard of bone repair. The degradation of the composites in the presence of CA and SF was significantly delayed such that the degradation rate of the implant could satisfy the growth rate of the newly formed bone tissue. The in vitro tests confirmed that the CA-SF/HA composite scaffolds enabled the MG63 cells to proliferate and differentiate well, and the CA/HA composite presented greater capability of promoting the cell behaviors than the NA/HA composite. After 24 days of implantation, newly formed bone was observed at the tibia defect site and around the implant. Extensive osteogenesis was presented in the rats treated with the CA-SF/HA composites. In general, the CA-SF/HA composites prepared in this work had the great potential to be applied for repairing large bone defects.
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高影响因子
DALTON TRANSACTIONS
·
2016
·Vol. 45
·期 27
·11129-11136
·
IF 4.177
Yue Su,Xiuling Liu,Pengpeng Lei,Xia Xu,Lile Dong,Xianmin Guo,Xingxu Yan,Peng Wang,Shuyan Song,Jing Feng,Hongjie Zhang
Core–shell–shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) have been successfully fabricated via the thermal decomposition method. Upconversion nanoparticles (UCNPs) were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectroscopy, etc. Under 980 nm excitation, the emission intensities of the UCNPs are remarkably enhanced after coating the MF2 (M = Ca, Sr, and Ba) shell. Among these samples, CaF2 coated UCNPs show the strongest overall emission, while BaF2 coated UCNPs exhibit the longest lifetime. These results demonstrate that alkaline earth metal fluorides are ideal materials to improve the UCL properties. Meanwhile, although the lattice mismatch between the ternary NaREF4 core and the binary MF2 (M = Sr and Ba) shell is relatively large, the successfully synthesized NaLuF4:Yb/Er@NaLuF4:Yb@MF2 indicates a new outlook on the fabrication of heterostructural core–shell UCNPs.
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POLYMER DEGRADATION AND STABILITY
·
2017
·
IF 3.386
Mei Li,Jianling Xia,Haiyang Ding,Chengxiang Ding,Mei Wang,Shouhai Li
An adduct of myrcene and maleic anhydride (AMMA) was synthesized using a Diels-Alder reaction. The adduct was transformed into the corresponding sodium , calcium salt and zinc salts (Na-AMMA, Ca-AMMA, and Zn-AMMA) using a metathesis reaction . The chemical structures of AMMA, Na-AMMA, Ca-AMMA, and Zn-AMMA were confirmed with Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), 1 H and 13 C nuclear magnetic resonance ( 1 H NMR and 13 C NMR), and X-Ray Diffraction (XRD). Mixed Ca/Na/Zn salts from AMMA provided thermal stabilization for poly (vinyl chloride) (PVC). The thermal and mechanical properties of the PVC samples were investigated using discoloration and Congo red tests, scanning electron microscopy analysis (SEM), thermal gravity analysis (TGA), TGA–FTIR analysis, thermal gravity-mass spectrometer analysis (TGA-MS), and dynamic mechanical analysis (DMA). Optimal design of the Ca/Na/Zn-AMMA formulation was studied. The application of Ca/Na/Zn-AMMA in an optimized formulation for a biobased, primary thermal stabilizer for PVC could significantly improve PVC thermal stability. The optimized Ca/Na/Zn-AMMA formulation had higher thermal stability, higher storage modulus , and lower glass transition temperatures than PVC blends without any thermal stabilizers and using commercial CaSt 2 /ZnSt 2 . The weights of the Ca/Na/Zn-AMMA samples were 33.3–75.0% that of CaSt 2 /ZnSt 2 , but provided higher thermal stability. Myrcene-derived Ca/Na/Zn-AMMA was shown to have strong potential as a primary PVC thermal stabilizer.
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高影响因子
FUEL
·
2025
·
IF 7.5
Dawei Wu,Aijia Zhang,Jing Liu,Yingju Yang
MFe 2 O 4 (M = Ca, Mn, Co, Ni, Cu and Zn) spinel sorbents were synthesized by a low-temperature sol–gel auto-combustion method for arsenic adsorption from flue gas. CuFe 2 O 4 spinel exhibited the highest arsenic removal performance among these sorbents, and the adsorption capacity reached 14.09 mg/g at 800 °C. The pseudo-first order, pseudo-second-order and Elovich kinetic models can well predict arsenic removal process, which indicates that the mass transfer and chemisorption processes are important during arsenic capture by CuFe 2 O 4 . The impact of incineration flue gas components on As 2 O 3 adsorption was elucidated. It was found that HCl showed negligible effect on arsenic removal by CuFe 2 O 4 sorbent while CO 2 , H 2 O, SO 2 and NO played inhibition roles. X-ray photoelectron spectroscopy results revealed that the adsorbed arsenic exists in the forms of As 3+ and As 5+ on the sorbent surface. The chemisorption and oxidation mechanisms are responsible for arsenic adsorption by CuFe 2 O 4 . The toxicity characteristic leaching procedure and sequential extraction experiments demonstrated that arsenic can be considerably immobilized in the CuFe 2 O 4 sorbent. The high arsenic capture capacity, excellent HCl resistance and low risk of secondary contamination make CuFe 2 O 4 an efficient sorbent for gaseous arsenic capture.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2025
·
IF 5.4
Yang Zhang,Hanjun Wu,Zhenyue Zhang,Wenda Guo,Junxia Yu,Rongying Zeng,Ruan Chi,Zhiquan Pan
In this work, Ca-Al LDHs were modified via co-precipitation method utilizing two distinct chemical forms of adipic acid (adipate salt and adipic acid) as intercalation agents, with the resulting materials denoted as At-LDHs (adipate-intercalated LDHs) and Aa-LDHs (adipic acid-intercalated LDHs). The results indicated that At-LDHs and Aa-LDHs all exhibit a sheet-like porous structure stacked with each other. Due to the different synthesis conditions, the sheet structure of Aa-LDHs is smaller than that of At-LDHs. The kinetic and isotherm simulation results indicated that the capture capacity of At-LDHs for Mn 2 + was up to 227.53 mg·g −1 when the pH value was 7, while that of Aa-LDHs for naphthol green B reached to 132.73 mg·g −1 at a pH value of 9. The kinetic and thermodynamic simulation results indicated that the capture of Mn 2+ by At-LDHs conformed to the pseudo-first-order kinetic model and the Langmuir isotherm model, and the capture of naphthol green B by Aa-LDHs conformed to the Elovich kinetic model and the Temkin isotherm model. In addition, the capture process of both was a spontaneous exothermic reaction. Benefiting from the excellent adsorption properties of At-LDHs composites (Ion exchange, electrostatic attraction, adsorption precipitation, functional group chelation), the adsorption effect on Mn 2+ was better. Aa-LDHs have good adsorption effect on naphthol green B in solution through electrostatic attraction, dipole-dipole hydrogen bond, Yoshida hydrogen bond and n-π interaction. At-LDHs and Aa-LDHs have great potential to be employed as the materials for the removal of organic and inorganic composite pollutants from wastewater.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yuxuan Zhang,Jian Sun,Yuyao Tan,Yi Shi,Zijian Zhou,Chuanwen Zhao,Wenqiang Liu
Solar radiation heat replaces pulverized coal as the heat source in the calcination reactor of the direct solar-driven Calcium Looping (CaL) system, eliminating the adverse impact of in-situ coal combustion on Ca-based sorbents. To ensure the system’s efficiency, the Ca-based sorbents must exhibit strong light absorption capabilities, with manganese incorporation being an effective strategy to enhance this characteristic. The integration of impregnated layer solution combustion with hydrophobic layer-assisted casting is a promising approach for fabricating highly efficient Mn-incorporated Ca-based sorbent pellets. Constructing Mn-incorporated Ca-based sorbent pellets with a graphite hydrophobic layer results in better performance compared to using a Nano-TiO 2 hydrophobic layer. The latter is prone to forming a white shell on the sorbent pellets’ surface, which seriously affects the light absorption features. High levels of Mn loading work to increase the optical absorbance of hydrophobic graphite layer assisting-casted Ca-based sorbent pellets, but this inevitably leads to a sacrifice in their CO 2 sorption capacity. Therefore, the core–shell structured Ca-based sorbent pellets, comprising a highly active Al-stabilized CaO pristine core and a dark Mn-based outer shell, fabricated with a graphite/MnO 2 mixture as the hydrophobic layer, exhibit exceptional optical absorbance (88.4 %) alongside excellent CO 2 sorption capabilities (maintaining average CO 2 uptake of 0.39 g/g during 20 cycles), making them optimal candidates for direct solar-driven CaL.
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CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Jian Zhou,Changyou Liu,Jinshan Lu
The utilization of granite sludge offers significant economic and environmental advantages. This study focuses on preparing porous glass-ceramics from Ca(OH) 2 -modified granite sludge through a two-step sintering process comprising dense sintering and high-temperature foaming, with the addition of 1 % SiC powder as a foaming agent. The impact of foaming temperature and Ca(OH) 2 addition on the structure, compressive strength , specific strength , and thermal conductivity of the porous glass-ceramics is examined. Incorporating the Ca(OH) 2 modifier reduces the glass's viscosity and effectively eliminates micropores on the pore walls. The former promotes foaming and increases porosity, while the latter increases the specific strength of porous glass-ceramics. Increasing both the foaming temperature and the Ca(OH) 2 concentration reduces glass viscosity and promotes mineral dissolution, facilitating the foaming process. However, the specific strength of the porous glass-ceramics initially increases before decreasing due to pore coalescence and excessive mineral dissolution. Theoretical evaluations of compressive strength and thermal conductivity indicate that porous glass-ceramics possess a closed-cell pore structure . Porous glass-ceramic made from granite powder containing 3.5 % Ca(OH) 2 and foamed at 1240 °C exhibits an apparent density and porosity of 0.73 g/cm 3 and 67.1 %, respectively. The compressive strength and thermal conductivity are 14.2 MPa and 0.422 W/(m·K) respectively, with a peak specific strength of 19.4 kN·m/kg. This innovative process enables the scalable recycling of granite sludge into energy-saving building materials.
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ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Ying Zhong,Xiao Chen,Shiyao Liu,Huibin Liu,Deng Hu,Gwendoline Lafaye,Changhai Liang
The industrial advancement of downstream products resulting from the directed hydrogenation of maleic anhydride is hindered by the limitations related to the activity and stability of catalysts. The development of nonprecious metal intermetallic compounds, in which active sites are adjustable in the local structures and electronic properties embedded within a distinct framework, holds immense potential in enhancing catalytic efficacy and stability. Herein, we report that nickel-based silicides catalysts, RNi2Si2 (R = Ca, La, and Y), afford high efficiency in the selective hydrogenation of maleic anhydride. Among the RNi2Si2 with the same tetragonal structure, CaNi2Si2 with complete isolation and highest electron density of Ni sites presents the low apparent activation energy (98.4 kJ/mol). Preferential adsorption of intermediate succinic anhydride via C═O bonds is achieved by the high oxygen affinity of CaNi2Si2, resulting in chemoselectivity to γ-butyrolactone (>80%). Additionally, the silicide with good resistance to sintering and acid corrosion presents remarkable stability for at least 130 h. The design of the silicide structure will offer fresh perspectives on the development of effective and enduring selective hydrogenation catalysts.
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高影响因子
Catalysis Science & Technology
·
2025
·
IF 4.2
Dajian Li,Alfin Kurniawan,Tania Roy,Jin Wang,Cheng lan Liu,Ze Zhen Wang,Rong Zhen Mu,Chun Hui Zhou
The efficient production of allyl alcohol from glycerol is of great importance due to its significance as a valuable intermediate in chemical industries. While catalytic conversion of glycerol to allyl alcohol by solid acid catalysts, carbon deposition (coking) is prone to occur on the catalyst surface, leading to slow down the conversion process and fast deactivation of the catalyst. In this study, we obtained an efficient catalyst for the preparation of allyl alcohol from gas-phase glycerol by controlling the pore structure and surface acidity of the catalyst. The characterization results showed that hydrochloric acid and citric acid removed the silicon and aluminium elements from montmorillonite, and the acidity, pore volume, and surface area ratio of Na-MMT (SBET=34.5 m2 g-1, VT=0.19 cm3 g-1) of the porous montmorillonite(HA1MMT) catalyst were all improved (SBET=97.9 m2 g-1, VT=0.28 cm3 g-1); After adding MoOx and VOx, the selectivity of Mo/V-HA1MMT catalyst for allyl alcohol was improved. The XPS characterization results indicate that the synergistic effect of Mo and V can promote the transfer of electrons during the reaction process of glycerol conversion. Within 480 minutes of catalyzing glycerol dehydration reaction, Mo0.6V0.4(5)-HA1MMT was almost deactivated (Conv.= 19.5%, Sel.allyl alcohol=31.2%) due to carbon deposition. When the catalyst was doped with calcium and magnesium components, a new active phase CaMo4 was discovered on the catalyst, and the acidity of Ca0.5Mg0.5-Cat. (Cat. is Mo0.6V0.4(5)-HA1MMT) decreased to 214.0 μmol g-1. The coking resistance performance of Ca0.5Mg0.5-Cat. was improved, and after 660 minutes of reaction, the catalyst was deactivated (Conv.= 32.1%, Sel.allyl alcohol=30.1%) due to carbon deposition. During the 3rd catalyst regeneration test, Ca0.5Mg0.5-Cat. still maintained high activity (Conv.= 63.3%, Sel.allyl alcohol=35.2%, Sel.acrolein=31.2%). The results of this study indicate that suitable pore structure and acidity are crucial for designing a catalyst with coking resistance properties.
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