RSC Advances
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2018
·Vol. 8
·期 16
·8965-8975
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IF 2.936
Meng Xia,Wenjie Dong,Minyan Gu,Cheng Chang,Zheng Shen,Yalei Zhang
An experimental study was carried out to convert carbohydrates using bimetal modified beta zeolite to obtain a maximum yield of lactic acid. The relationship between the properties and the catalytic performance of various bimetal modified beta zeolites was evaluated. The results showed that the maximum yield of lactic acid reached 52% with more than 99% glucose conversion over Pb–Sn-beta (0.3 mmol g−1, Pb/Sn = 4 : 7) at 190 °C for 2 h under ambient air pressure. To evaluate the synergetic mechanism of lead and tin, key intermediates such as fructose, dihydroxyacetone, glyceraldehyde and pyruvaldehyde were used as probe reactants that were catalyzed by Pb-beta, Sn-beta and Pb–Sn-beta. The revealed key role of lead was to promote the isomerization of glucose to fructose and the retro-aldol condensation reaction from fructose to dihydroxyacetone and glyceraldehyde; meanwhile, tin had a superior catalytic performance in the dehydration of dihydroxyacetone, the hydration of pyruvaldehyde and the isomerization of pyruvic aldehyde hydrate.
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RSC Advances
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2018
·Vol. 8
·期 5
·2586-2592
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IF 2.936
Boyang Xu,Youlin Liu,Yuesong Shen,Shemin Zhu
A facile method is to prepare novel CeMoxOy-clay hybrid catalysts with layered structures by using organic cation modified clay as support. During the preparation process, cerium cations and molybdate anions are easily adsorbed and impregnated into the interlamellar space of the organoclay, and after calcination they undergo transformation to highly dispersed CeMoxOy nanoparticles within the interlamellar space of the clay. As expected, the prepared CeMo0.15Ox-OC-T catalysts with layered structures had high selective catalytic reduction (SCR) activity such as high NOx conversion of >90% in the wide temperature range of 220–420 °C. Meanwhile, they also exhibit high stability and tolerance to water vapor (5 vol%) and SO2 (200 ppm), demonstrating that these novel catalysts could serve as a good alternative for NH3-SCR in practical application.
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Catalysts
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2018
·Vol. 8
·期 1
·20
·
IF 3.465
Wenjie Xue,Zenglong Wang,Yu Liang,Hong Xu,Lei Liu,Jinxiang Dong
Bismuth plays important roles in promoting the oxidation of alcohols towards high-value-added chemicals over a noble metal loading catalyst. Herein, Mg–Al hydrotalcite-supported platinum–bismuth nanoparticles (Pt–Bi/HT) were prepared by the co-impregnation method and used in the selective oxidation of glycerol towards dihydroxyacetone (DHA). The incorporation of Bi species into Pt/HT significantly enhances the conversion of glycerol and the selectivity of DHA. The high selectivity of DHA with 80.6% could be achieved at 25.1% conversion of glycerol. The Bi species of the Pt–Bi/HT catalyst mainly exist in the form of BiOCl and Bi metal, which is different from the previous Pt–Bi based catalyst, confirmed by a combination of powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HR-TEM). A plausible mechanism is proposed to elucidate the promoting role of Bi species on the Pt/HT catalyst in the selective oxidation of glycerol towards DHA.Keywords:Mg–Al hydrotalcite;platinum–bismuth nanoparticles;co-impregnation;glycerol oxidation;dihydroxyacetone
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CHEMICAL ENGINEERING JOURNAL
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2018
·
IF 6.735
Chao Shan,You Xu,Ming Hua,Min Gu,Zhichao Yang,Peng Wang,Zhenda Lu,Weiming Zhang,Bingcai Pan
Most heterogeneous catalysts available for catalytic ozonation are present as powders and not ideal for column operation in advanced water treatment. In this study, a mesoporous Ce-Ti-Zr ternary oxide (CTZO) millisphere of large size (0.8–1.0 mm in diameter) and high surface area (180 m 2 g −1 ) was synthesized as a highly stable catalyst to meet the hydrodynamic demand in column ozonation. The fraction of Ce(III) is much higher on the surface of CTZO (49.2%) than CeO 2 (27.5%), resulting in its high catalytic activity in ozone decomposition and mineralization of oxalic acid (OA), an ozone-refractory probe compound. The most favorable catalytic ozonation of OA was observed at pH 3.0 and the adsorption of OA by CTZO via surface complexation is a requisite step for its ozonation. The EPR analysis and radical scavenging experiment confirmed that OH was the dominating reactive species in catalytic ozonation of OA by CTZO. XPS revealed that the oxidation of OA was mediated by the Ce(III)/Ce(IV) redox cycle, which continously accepts the electron supply from OA ligand and meanwhile donates electron to activate O 3 into OH. The catalytic ozonation of OA by CTZO was enhanced in the presence of sulfate due to the generation of sulfate radical. Cyclic runs demonstrated that the CTZO millispheres exhibited high stability for sustainable catalytic ozonation of OA without noticeable release of Ce or change of Ce valence state. This study will provide new insight for the development of efficient ozonation catalysts towards practical application in advanced water treatment.
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ACS Sustainable Chemistry & Engineering
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2018
·
IF 6.14
Muhammad Tariq,Waqas Qamar Zaman,Wei Sun,Zhenhua Zhou,Yiyi Wu,Li-mei Cao,Ji Yang
Minimization of noble metal contents along with enhancement in electrochemical properties with high durability is a major challenge to be overcome for commercializing water electrolyzers and cheap energy storage devices. Sluggish kinetics of the oxygen evolution reaction (OER) within the electrolytic cell and high energy demand to form O═O bonds have attracted more responsiveness to this area. We report the OER beneficial mixed oxide composite of molybdenum and iridium oxides by a facile hydrothermal method. Adhered IrO2 nanoparticles on MoO3 large particles synergistically possessed a robust nature toward harsh acidic water electrolysis as compared to an alkaline environment. Mass specific OER activity of iridium active centers was greatly enhanced by 7-fold, twice the current density, and was attributed to electronic modulation of noble metal. Enhanced surface area and the existence of highly oxidative species in the O(1s) spectrum of IrO2 and two doublet regions in the X-ray photoelectron spectrum of molybdenum metal were found, accountable for the robust performance. Prepared composite possessing only 30% molar fraction of noble metal presented an excellent long-term stability for 40 000 s. Reduction in the Tafel slope from 57 to 77 mV dec–1 for IM-30 and IrO2 respectively was observed. The conducted research will open up new avenues for more applications of molybdenum oxides and their derivatives for water splitting.
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FUEL PROCESSING TECHNOLOGY
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2018
·
IF 3.956
Ting Lu,Yucui Hou,Weize Wu,Muge Niu,Wei Li,Shuhang Ren
Carboxylic acids are considered as an important group of chemicals. Direct conversion of cellulose to formic acid (FA) by vanadium(V(V))-contained catalyst is of significant conceptual and practical interest. A second metal (from Mg(II), Ca(II), Al(III), Cr(III), Mo(VI), Mn(II), Cu(II), or Fe(III)) incorporated into V(V)-contained catalyst system was screened to further improve the oxidation of cellulose by O 2 to yield FA. Fe(III) exhibited the best performance and effects of reaction parameters on the conversion of cellulose in NaVO 3 -FeCl 3 -H 2 SO 4 aqueous solution were investigated. Cellulose could be rapidly converted, and the yield of FA (66.8%) was higher than that obtained by the single use of FeCl 3 (48.4%) or NaVO 3 (57.6%). The conversion of cellulose in another V(V)-contained catalyst system (H 5 PV 2 Mo 10 O 40 ) was explored to verify the universal enhancement of FeCl 3 . Influences of the second metal Fe(III) on the V(V)-contained catalyst system and mechanism of cellulose oxidation in the V(V)-Fe(III)-H 2 SO 4 system were studied. Compared with single use of V(V), the employment of Fe(III) alone is not active enough in the oxidative C C bond cleavage . V(V) other than Fe(III) is the main active species for selective oxidation of substrates. The incorporation of Fe(III) and V(V) shows both synergistic and competitive relationships. Both the synergistic and competitive effects are beneficial to increase FA yield, as they promote the oxidation of V(IV) to V(V), increase oxidative ability, and inhibit the overoxidation to by-product CO 2 . The catalyst system was reused four times without decline in activity.
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Catalysts
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2018
·Vol. 8
·期 1
·37
·
IF 3.465
Yang Zheng,Yangyang Guo,Lei Luo,Tingyu Zhu
The performance of activated carbon (AC) modified by different methods was compared for its catalytic degradation of ortho-chlorophenol (o-CP). For the chemically treated AC, the catalytic effect of AC–NH3·H2O was superior to the other catalysts examined, having ano-CP removal efficiency of 82.2% at 330 °C. For the metal-modified catalysts, AC–V and AC–Co showed similar removal performances of 93.2% at 330 °C. N2adsorption-desorption isotherms, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and gas chromatography—mass spectrometry (GC-MS) analyses were used to characterize the reaction products, and different reaction mechanisms were proposed for both AC–NH3·H2O and AC–V according to the results. Complete oxidative degradation ofo-CP was achieved by AC–V, with AC–NH3·H2O leading to the formation of additional dioxins. It can be deduced that a risk of dioxin synthesis and escape during the regeneration process is possible when nitrogen-modified carbon is used in selective catalytic reduction (SCR) denitrification reactions, especially in the presence of chlorine atoms, benzene rings, and oxygen.Keywords:catalysis;modified carbon;ortho-chlorophenol;degradation mechanism
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FUEL
·
2024
·
IF 6.7
Hongbin Xia,Yuxin Wang,Rui Xia,Xinyang Xiong,Guangwen Xu,Jinggang Zhao,Jun Zhou,Lei Shi
An acetate-functionalized heterogeneous catalyst, N + -(Ac), was successfully synthesized via directed substitution of an inert site in quaternary ammonium resin by a weak-base active center and applied to the transesterification of dimethyl oxalate (DMO) with ethanol to prepare diethyl oxalate (DEO). When the optimal N + -(Ac) catalyst catalyzed the DMO transesterification with ethanol for 2 h, the DMO conversion, DEO yield, and corresponding turnover frequency (TOF) reached 93.4%, 49.7%, and 13.04 h −1 , respectively. Additionally, the synthesized N + -(Ac) exhibited catalytic universality for DMO transesterification with different alcohols, and the catalytic efficiency decreased with increasing difficulty of cleaving the hydrogen–oxygen bond from C 2 to C 4 and steric hindrance of isomeric alcohols. The pretreatment experiments of catalyst with different water content and raw materials were designed and the resin matrix, fresh catalyst, deactivated catalyst and regenerated sample were systematically analyzed using various characterization techniques to investigate the catalytic deactivation mechanism of the transesterification reaction between DMO and ethanol to synthesize DEO. The results showed that DMO played a key role in catalyst deactivation and the catalyst was deactivated upon replacement of the active sites by monomethyl oxalate anions from hydrolysis side reaction of DMO. Finally, an efficient raw material regeneration strategy for the catalyst was proposed. Herein, new theoretical support is introduced for the structural evolution of weak-base catalysts and will aid in developing heterogeneous catalysts for oxalate transesterification.
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CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Qinghua Li,Xuping Liu,Chunyan Deng,Deng Wang,Zixia Chen,Jiewen Xu,Xiao Jin,Jihuai Wu
High power conversion efficiency (PCE) and long-term stability are the keys to the commercialization of perovskite solar cells (PSCs). However, the defects of formamidinium lead tri-halide (FAPbI 3 ) perovskite films limit the PCE of the device to the Shockley Queisser limit. The conventional strategies for enhancing the properties of perovskite films often pivot on the selective interaction between a passivating agent and a solitary constituent within the perovskite matrix. Herein, we present an alternative dual-site regulation approach using 6-fluorobenzamide (6-FB) to modulate the reaction kinetics of Pb and I, resulting in FAPbI 3 films with fewer defects and significantly enhanced carrier lifetimes. 6-FB can not only passivate the uncoordinated Pb 2+ defects and iodine vacancies. The optimized PSCs achieved a PCE of 25.03 % (certified at 24.25 %) with an area of 0.0625 cm 2 , and retained 94.1 % of their initial PCE after storage in ambient air (∼10 relative humidity, RH) for over 800 h. This method expands the scope of chemical interactions possible by leveraging the interaction between 6-FB and the perovskite.
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JOURNAL OF MOLECULAR LIQUIDS
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2024
·
IF 5.3
Han-Qing Pang,Jia-Xiu Guo,Yang Yang,Chuan Jiang,Xuan-Hao Zhang,Wei Shi,Chun-Yang Bi,Bing-Chun Yan
Polygonum multiflorum Thunb. (Heshouwu in Chinese, PMT) is commonly used as a food supplement due to its anti-aging effects. Maximizing the recovery of active compounds and removing hepatotoxic compounds from PMT are effective ways to reduce side effects. In this study, 71 deep eutectic solvents (DESs) were prepared to simultaneously extract active compounds and remove hepatotoxic compounds from PMT by ultrasound-assisted extraction. Betaine-sorbitol (Bet-Sor, 1:1.2 mol/mol) was screened as the most appropriate DES in this series. Afterwards, the major extraction parameters were optimized using single-factor tests and response surface methodology. The optimal conditions (water content of DES of 46.22 %, liquid/solid ratio of 42.50, and extraction time for 20.76 min) resulted in the maximum total contents of active compounds (25.612 mg/g). Compared with conventional extraction solvents, the highest/lowest extraction amounts of active/hepatotoxic compounds were obtained. At the meantime, Bet-Sor exhibited the highest anti-oxidative effects and the lowest hepatotoxicity on HepG2 cells. The scanning electron microscopy test revealed that the cell walls of PMT cells were extremely injured by Bet-Sor, thus the active components could be fully extracted. These results revealed that DES-based extraction provided a simple, ecofriendly and feasible detoxication strategy to ensure the effective and safe utilization of PMT.
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INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
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2025
·
IF 3.1
Peng Yijin,Yun Yurou,Zou Wenhui,Zhou Linyan
Our study analysed the quality differences between 6 pomegranate varieties grown in Yunnan. The results showed that the composition and contents of anthocyanins, the amount of polymeric pigments produced by the reaction between anthocyanins and tannins, and pH were the primary factors affecting the colour of pomegranate arils. Fructose and citric acid were the main sugar and organic acid contributing to the taste of pomegranate arils. In total, 42 phenolic compounds were identified, with BS being classified as a distinct group due to higher concentrations of ACNs and flavonols. Additionally, 32 volatile compounds were identified, with TLZ, SP, and TGY grouped, BS, TNS, and HRY grouped into another. The key phenolic metabolic pathways included flavone and flavonol biosynthesis, anthocyanin biosynthesis, and phenylpropanoid biosynthesis, while fatty acid biosynthesis, pyruvate metabolism, and sulfur metabolism were the main volatile metabolic pathways. These results provide valuable guidance for agricultural practices and promoting industrial development.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2024
·
IF 8.1
Jiang Liu,Bingxue Chen,Yukun Huang,Yijun Cao,Jingbo Chen,Liqiang Wang,Yan Liu,Yangyang Fan
Indium, a strategic key metal, is mainly recovered from zinc leaching residue. However, a challenging problem in the treatment of zinc leaching residue is how to efficiently and cleanly treat the poorly soluble phase, the indium-bearing zinc ferrite (IBZF). Here, we propose a novel strategy for the selective extraction of indium , zinc and iron from IBZF. By introducing water to regulate the coordination environment of a choline chloride-anhydrous oxalic acid based deep eutectic solvent (ChCl-Oxa based DES), efficient leaching and deep separation of indium , zinc and iron were achieved. Water, acting as both co-solvent and diluent, played a critical role in the whole process. The addition of a little water reduces the viscosity of the DES, thereby improving the leaching of indium , zinc and iron. Under specific leaching conditions (leaching temperature of 90 °C, liquid/solid ratio of 20:1 ml/g, molar ratio of ChCl:Oxa = 1:1, molar ratio of DES:H 2 O = 1:3 and reaction time of 3.5 h), the leaching efficiencies of indium, zinc and iron were 96.27 %, 95.55 % and 96.33 %, respectively. The subsequent addition of large amounts of water dilutes and dissociates the structure of the DES, facilitating the stepwise precipitation and deep separation of metal ions. The precipitation efficiency of zinc and iron reached 93.06 % and 98.07 %, respectively. Residual indium ions in the solution were effectively adsorbed by activated carbon, with a recovery efficiency of 75.7 % after five cycles of adsorption. The solution separated from the metal ions was well regenerated by evaporation and addition of Oxa. Our work represents a novel approach for the recycling and clean utilization of zinc leaching residue. And the regulation of the coordination environment of metal ions in DES is proved to have great potential in metal recycling.
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