Catalysis Science & Technology
·
2016
·Vol. 6
·期 14
·5656-5667
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IF 5.287
Fufeng Cai,Guomin Xiao
In this work, a series of Cu–Co–Al catalysts with different Ce loadings were applied to the hydrogenolysis of glycerol to 1,2-propanediol in a fixed-bed flow reactor. The physicochemical properties of the synthesized catalysts were analyzed using BET, N2O chemisorption, SEM, TEM, XRD, H2-TPR, NH3-TPD and XPS techniques. Systematic characterization demonstrated that the incorporation of Ce into the Cu–Co–Al catalyst could effectively restrain the aggregation of active metal species as well as the growth of metallic particles during calcination and reduction, which resulted in the formation of highly dispersed active metals. Large amounts and superior strength of acid sites were present in the Ce-promoted Cu–Co–Al catalysts, as confirmed by NH3-TPD analysis. The reducible nature of the Cu–Co–Al catalyst greatly increased after the addition of Ce. The higher concentration of acid sites, excellent reducibility and highly dispersed active metals were responsible for the superior catalytic activity of the 8Ce/Cu–Co–Al catalyst and it attained 91.6% glycerol conversion and 92.4% 1,2-propanediol selectivity. In addition, the effects of different process parameters such as the solvent, reaction temperature, operating pressure, catalyst loading, glycerol concentration and liquid flow rate on glycerol hydrogenolysis together with the catalyst stability were studied in detail, showing that the Ce-promoted Cu–Co–Al catalyst had high efficiency and stability for glycerol hydrogenolysis.
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CATALYSIS TODAY
·
2017
·
IF 4.636
Xinli Tong,Linhao Yu,Xuan Luo,Xuli Zhuang,Shengyun Liao,Song Xue
The efficient transformation of furfural (FUR) with aliphatic alcohols to achieve the carbon-chain growth has been developed using a binary Cu-Ce oxide as the catalyst. In the presence of molecular oxygen, the tandem oxidative condensation of FUR with n -propanol is successfully performed, in which an 85.4% conversion of FUR in 95.3% selectivity of 3-(furan-2-yl-)-2-methylacryaldehyde was obtained. The effects of different Cu/Ce ratios and base additives were investigated in detail. As a result, it is found that the CuO-CeO 2 (1: 9) catalyst is optimal and potassium carbonate is a suitable additive. Next, the recycling of CuO-CeO 2 catalyst was tested and there is no obvious activity loss after being reused five times. Moreover, the oxidative condensation of FUR with various aliphatic alcohols including ethanol, isopropanol, n -butanol and n -hexanol was studied where the long chain alcoholic molecule hinders the proceeding of reaction. Finally, based on the experimental results and reaction phenomena, a possible mechanism for the oxidative condensation of FUR with n -propanol-O 2 is proposed.
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APPLIED CATALYSIS A-GENERAL
·
2017
·
IF 4.339
Baohuai Zhao,Rui Ran,Xingguo Guo,Li Cao,Tengfei Xu,Ze Chen,Xiaodong Wu,Zhichun Si,Duan Weng
Mn/Ce/Ti and Mn/Ce/Nb/Ti catalysts were synthesized using a precipitation method and their catalytic activities for NO selective reduction with NH 3 at low temperatures were evaluated. Nb doping not only improved the activity of the catalyst over a wide temperature range but also restricted the generation of NO 2 and N 2 O. The Mn/Ce/Nb/Ti catalyst displayed 100% NO conversion from 150 to 250 °C and >90% N 2 selectivity below 250 °C. The specific surface area of the catalyst was increased and its surface acidity was strengthened after Nb doping. Moreover, Nb doping increased the NO oxidation ability and lowered the NH 3 oxidation activity of the catalyst. All the above factors contributed to enhancing the overall NH 3 -SCR performance of the Mn/Ce/Nb/Ti catalyst compared with that of the Mn/Ce/Ti one. The long-term stability and resistance to H 2 O and SO 2 of the Mn/Ce/Nb/Ti catalyst were also evaluated.
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JOURNAL OF NUCLEAR MATERIALS
·
2015
·
IF 1.865
Kuibao Zhang,Guanjun Wen,Dan Yin,Haibin Zhang
Synroc is recognized as the second generation waste form for the immobilization of high-level radioactive waste (HLW). Zirconolite-rich (CaZrTi 2 O 7 ) Synroc minerals were attempted by self-propagating high-temperature synthesis (SHS) using Fe 2 O 3 , CrO 3 , Ca(NO 3 ) 2 as the oxidants and Ti as the reductant . All designed reactions were ignited and sustained using Ca(NO 3 ) 2 as the oxidant, and zirconolite-rich ceramic matrices were successfully prepared with pyrochlore (Ca 2 Ti 2 O 6 ), perovskite (CaTiO 3 ) and rutile (TiO 2 ) as the minor phases. The sample CN-4, which was designed using Ca(NO 3 ) 2 as the oxidant with TiO 2 /Ti ratio of 7:9, was readily solidified with density of 4.62 g/cm 3 and Vickers hardness of 1052 HV. CeO 2 was successfully stabilized by the CN-4 sample with resultant phase constituent of 2M-CaZrTi 2 O 7 and CaTiO 3 .
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Yanping Yang,Shengchen Li,Shunli Shi,Jie Hu,Zexi Xuchen,Shunmin Ding,Dan zhao,Shengjun Deng,Weiming Xiao,Shuhua Wang,Chao Chen
Manganese oxide (MnO x ) catalysts are promising for low-temperature NH 3 -Selective Catalytic Reduction (NH 3 -SCR) with their superior catalytic performance. However, the presence of alkali metals in flue gases, particularly potassium (K), leads to catalyst deactivation and limits their industrial application. This study investigates the synergistic effects of Ce and Nb doping on the K resistance and low-temperature NH 3 -SCR activity of MnO x . The surface acidity and redox properties of MnO x were modulated by Ce and Nb modification. In addition, the phase structure, surface state and active sites of the catalysts were characterized before and after K poisoning. The results indicated that Nb 0.05 Ce 0.05 MnO x exhibited exceptional low-temperature performance, achieving over 90 % NO conversion at 125-250°C, along with significant resistance to K poisoning·NH 3 -TPD and in-situ experiments revealed that the loss of acid sites is the primary cause of K poisoning. The mechanism follows the L-H mechanism with L-acid sites as the main active sites on the catalyst surface and bridging nitrate as the key intermediate state. This research provides valuable insights into enhancing the industrial applicability of MnO x- based catalysts for low-temperature denitrification.
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Materials Today Communications
·
2024
·
IF 3.7
Kunyi Ma,Lin Liu,Yanan Wang,Di Wu,Qingyu Zhao,Jinjuan Xing
In this work, a new polyvinylidene fluoride nano-ultrafiltration membrane modified by graphene oxide/ titanium dioxide doped with cerium composite materials (GO/Ce-TiO 2 -PVDF) was prepared by phase inversion method. The water contact angle, porosity, pore size distribution , and photocatalytic performance of the membrane were studied. Compared with the PVDF membrane, the water contact angle of the modified membrane decreased to 36.5°, the pure water flux improved to 119.64 L·m -2 ·h -1 , and the retention rate of bovine serum albumin (BSA) was 95.3%. The synergistic effect of GO and Ce-TiO 2 could improve the photocatalytic activity of the composite membrane , and the degradation rate of BSA was 97.4%. The flux recovery rate (FRR) of the modified membrane was 82.38%, which was 22.24% higher than that of the PVDF membrane (67.39%). The FRR of the modified membrane increased to 91.54% under water cleaning and UV irradiation. Five cycle experiments showed that the permeate flux of the polluted membrane was further restored from 78.45 L·m -2 ·h -1 to 76.95 L·m -2 ·h -1 after UV irradiation, and the retention rate of BSA was maintained at about 95%. Therefore, as predicted, the GO/Ce-TiO 2 -PVDF membrane could be widely applied in the water treatment industry due to its high anti-fouling and self-cleaning performances.
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JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Shun Qiu,Zhanxun Chen,Ling Yu,Chuying Liu,Chenghan Ji,Pengfei Shen,Sikai Cheng,Hui Qiu,Zhuoyao Fang,Xiaolin Zhang
Herein, a highly efficient As(III) purifier Ce-Mn@N201 with excellent reusability was developed by stepwise precipitating hydrated cerium(IV) oxides (HCO) and hydrated manganese(IV) oxides (HMO) inside N201, a widely-used gel-type anion exchange resin . Owing to confinement of unique nanopores in N201, the in-situ generated nanoparticles (NPs) inside Ce-Mn@N201 were highly dispersed with ultra-small sizes of around 2.6 nm. Results demonstrated that HMO NPs effectively oxidized As(III) to As(V) with the conversion of Mn(IV) to Mn(II), while the generated Mn 2+ was mostly re-adsorbed onto the negatively-charged surface of HMO NPs. During the regeneration process by simple alkaline treatment , the re-adsorbed Mn 2+ was firstly precipitated as (hydr)oxides of Mn(II) and then oxidized to HMO NPs by dissolved oxygen to fully refresh its oxidation capacity. Though HCO NPs mainly served as adsorbent for arsenic, they could partially oxidize As(III) to As(V) at the beginning, while the oxidation capacities continuously diminished with the irreversible conversion of Ce(IV) to Ce(III). In 10 consecutive adsorption-regeneration cycle, Ce-Mn@N201 efficiently decontaminated As(III) from 500 μg/L to below 5 μg/L with Mn 2+ leaching less than 0.3% per batch. During 3 cyclic fixed-bed adsorptions, Ce-Mn@N201 steadily produced 8500–9150 bed volume (BV) and 3150–3350 BV drinkable water from the synthesized and real groundwater, respectively, with Mn leaching in effluent constantly < 100 μg/L.
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PubMed
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POLYMERS FOR ADVANCED TECHNOLOGIES
·
2024
·Vol. 35
·期 6
·e6474
·
IF 3.1
Yi Li,Ning Zhang,Yanchao Zhu,Min Cheng,Shuang Gao
In this work, surface-modified Ce-Zr oxides and ZnO nanoparticles were conveniently prepared by dopamine (Dpa) treatment and then composited with epoxy (EP) by hot pressing. Thermogravimetric analysis (TGA) and UV-shielding properties of the EP composites with surface modification with Dpa-CZ and Dpa-ZnO were measured. The TGA results showed that the modified treated fillers had no loss of heat resistance of the matrix and had an enhancement effect on the initial and maximum decomposition temperatures. In addition, the UV-shielding properties of EP composites after Dpa-CZ and Dpa-ZnO modifications both showed a significant enhancement effect compared to pure EP. The T(UVA) of the 0.5 wt% Dpa-ZnO modified composite decreased to less than 0.017%, and the T(UVB) decreased to less than 0.0059%. The T(UVA) of the 0.5 wt% Dpa-CZ modified composite decreased to less than 15.98%, and the T(UVB) decreased to below 1.14%. The composites have both excellent thermal stability and UV-shielding efficiency.
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APPLIED CATALYSIS A-GENERAL
·
2024
·
IF 4.7
Yating Xie,Nicui Yuan,Hongyang Liu,Lukai Luo,Jun Gong,Xiping Yin,Tengfei Li,Yonghua Zhou
Defect engineering by creating oxygen vacancies (OVs) and heterogeneous frustrated Lewis acid-base pairs (FLPs) emerged as an efficient strategy to enhance the selective conversion CO 2 to CH 4 . Considering the intrinsic FLPs contained in UiO-66-NH 2 (UNH for abbreviation), in this paper, the OVs was introduced therein by fabricating the Ce-doped UNH (denoted as UNH(Ce/Zr)) via one-step solvothermal route. The as-prepared UNH(Ce/Zr) catalyst exhibited the CH 4 yield of 31.02 μmol·g −1 ·h −1 accompanied with the CH 4 selectivity of 93 % and satisfying recycling stability. The XRD, SEM, FT-IR, XPS, TG, TPD and NH 3 in situ DRIFTS and in situ FT-IR characterization results justified that the UNH(Ce/Zr) possess the obviously increased OVs sites and enhanced Lewis acidic and basic properties. Additionally, the photoelectrochemical characterization results showed that UNH(Ce/Zr)−0.014 efficiently improved photogenerated electron-hole separation efficiency and charge transfer rate. It could be concluded that it was the cooperative action of OVs and FLPs that led to the high CH 4 selectivity and CH 4 yield.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2025
·
IF 5.4
Mengqi Bian,Rui Liu,Qinghai Zhang,Yunlong Qu,Guanghui Chen,Jihai Duan,Hui Zhao,Weiwen Wang
The one-step preparation of methacrylic acid from isobutylene presents a significant challenge. In this study, three-dimensionally ordered macroporous (3DOM) Mo-V-P-Ce was synthesized using the hard template method and employed as a carrier for heteropolyacids in the selective oxidation of isobutene (IBN) to produce methacrylic acid (MAA). The CuNH 4 PAV@3DOM Mo-V-P-Ce catalyst developed through this method exhibits an ordered macroporous structure, which significantly enhances its thermal stability. Additionally, it contains a significant number of active species (VO 2 + ) and appropriate moderately strong acidic centers, which collectively improve the overall performance of the catalyst. The combination of CuNH 4 PAV with the 3DOM structure increases the surface concentration of oxygen vacancy species, thereby promoting the catalytic activity of the composite catalyst in converting these oxygen vacancy species into lattice oxygen species. Notably, the selectivity of the synthesized heteropolyacid catalysts for MAA increased to 84 % after loading. This work offers a novel approach to the development of efficient catalysts.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Xuebi Du,Dawei Shao,Shichao Feng,Yinhua Wan
Two-dimensional (2D) metal–organic framework nanosheets (MONs) materials exhibit significant potential in achieving high CO 2 separation performance. This study presents a demonstration of the rapid synthesis of Ce 6 BTB nanosheets at a low temperature of 80 °C and atmosphere pressure of approximately 1 atm. The resulting Ce 6 BTB nanosheets possess notable characteristics, such as high aspect ratios and 1D diamond shaped channels, which facilitate the fast rapid transport of CO 2 molecules. The Ce 6 BTB was firstly blended into PIM-1 with different loadings to form PIM/Ce 6 BTB mixed matrix membranes (MMMs). The incorporation of well-dispersed Ce 6 BTB fillers enhances the efficiency of CO 2 transport by inter-flake nano-channels and intra-flake pores. Moreover, the increased crystallinity, dense chain spacing, and hydrogen bonding contribute to enhanced sieving ability, resulting in high gas selectivity. Consequently, the MMMs containing 2 wt% Ce 6 BTB demonstrate high CO 2 permeability of 5930 Barrer and CO 2 /N 2 selectivity of 23.2, which is far surpasses 2008 upper bound from Robeson and approaches the refined 2019 upper bound from MeKenow. Furthermore, the PIM/Ce 6 BTB-2 MMMs present relatively good anti-pressure properties and long-term operation stability, which is advantageous in terms of industrial applications.
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Materials Science and Engineering B-Advanced Functional Solid-State Materials
·
2025
·
IF 4.6
Yiqing Wu,Xiangmei Ma,Bin Wang,Yanan Li,Shengtao Gao
The detrimental effects of ultraviolet (UV) and electromagnetic (EM) radiation on human health and physiological functions are well documented. The development of efficient shielding materials to mitigate these effects is therefore an urgent necessity. In this study, Zn/Ti-LDH@Ce/Fe-MOF@PPy composites were successfully prepared by hydrothermal synthesis and interfacial polymerisation. The properties of the composites were compared and analysed with those of pure Zn/Ti-LDH and Ce/Fe-MOF, and the results show that the prepared materials have excellent comprehensive properties, with a broad EAB of 5.2 GHz and a RL min of −46.2 dB at 14.8 GHz at the thickness of 3 mm, while exhibiting excellent UV shielding capability.The present study offers novel concepts and efficacious methodologies for the engineering of high-performance microwave absorbing and UV shielding materials.
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