查看更多>>摘要：Hormuz Red Soil (HRS), as a naturally hematite-containing mineral was used to enhance the catalytic ozonation process (COP) of Acetaminophen (ACT) elimination. The surface properties and particle size of HRS mainly composed of alpha-Fe2O3 were modified via calcination (C-HRS) demonstrating notable catalytic activity. The catalytic activity of C-HRS was evaluated for the ozonation of ACT under various conditions. Complete degradation of 50 mg L-1 ACT was obtained within 10 min at natural conditions with 1.0 g L-1 of C-HRS which was > 10 times faster than single ozonation process (SOP). The C-HRS accelerated the decomposition of ozone to hydroxyl radical on the catalyst's surface. Moreover, the C-HRS efficiently catalyzed the peroxone reaction for the degradation and mineralization of ACT. The C-HRS exhibited high stability and reusability in consecutive catalytic cycles. This work offers a new, effective, and low-cost catalyst for accelerating of ozone decomposition that can be used in oxidation of pollutants.
查看更多>>摘要：Ion imprinted CdS/HTNW photocatalytic membrane (IM-Cd/HT membrane) was prepared by assembling the oxidation type H2TinO2n+1 center dot xH(2)O nanowires (HTNW) and the reduction type ion imprinted CdS (IM-CdS) for the removal of Cr6+ and tetracycline. Due to the imprinted cavities, Cr6+ was preferentially adsorbed and trapped at specific reaction sites for reduction reactions under the interference of other ions, and the selective reduction coefficients reached 80.01-fold and 91.92-fold. More intriguingly, Cr6+ and tetracycline reacted on the IM-Cd/HT membrane in a heterotopic manner, Cr6+ migrated to IM-CdS for selective reduction, while tetracycline migrated to HTNW for synergistic oxidation, and there was no interference between the two reactions, thereby IM-Cd/HT membrane exhibited a good synergistic balanced removal effect for Cr6+ and tetracycline. Besides, the Cr6+ flux of IM-Cd/HT membrane reached about 2952 L m(-2) h(-1) bar(-1), and the rejection rate of Cr6+ was 62.02%. This study provides a reference for the design of functional self-cleaning membrane with good synergistic photocatalytic ability.
查看更多>>摘要：The dynamic nature of active sites on La-Fe-based perovskites in chemical looping methane oxidation has been studied. According to experimental observations, the reduction of the oxygen carrier is divided into three stages occurring at different active ensembles where the Fe cations are in different coordination environments. The Mars van Krevelen mechanism formulated by microkinetic analysis describes well the effect of oxygen vacancy on the catalytic performance of LaFeO3. CO2 is not produced by CO oxidation but rather is a primary product of methane oxidation, and the presence of surface oxygen vacancies would dramatically increase the overall energy barrier for total combustion, thus decreasing the selectivity toward CO2. Hence, the Fe coordination environment (and hence the oxygen vacancy concentration) is the key parameter governing the catalyst selectivity, in the sense that methane oxidation can vary from total combustion on the O-rich surface to fully selective partial oxidation on the O-deficient surface.
查看更多>>摘要：Modifying and controlling sites at the metal/oxide interface is an effective way of tuning catalytic activity, beneficial for bifunctional catalysis by reducible oxide supported metal nanoparticles. We employed mixed ceriapraseodymia supported Au clusters for the water gas shift reaction (WGSR). Varying the Ce: Pr ratio (4:1, 2:1, 1:4) not only allows to control the number of oxygen vacancies but, even more important, their local coordination, with asymmetrically coordinated O# being most active for water activation. These effects have been examined by X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), Xray photoelectron spectroscopy (XPS), Raman spectroscopy, temperature programmed desorption/reduction (TPD/TPR), and density functional theory (DFT). Using the WGSR performance of Au/CeOx as reference, Au/ Ce4Pr1Ox was identified to exhibit the highest activity, with a CO conversion of 75% at 300 degrees, which is about 5times that of Au/CeOx. Au/Ce4Pr1Ox also showed excellent stability, with the conversion still being 70% after 50 h time-on-stream at 300 degrees. Although a higher Pr content leads to more O vacancies, the catalytic activity showed a "volcano behavior". Based on DFT, this was rationalized via the formation energy of oxygen vacancies, the binding energy of water, and the asymmetry of the O# site. The presented route of creating active vacancy sites should also be relevant for other heterogeneous catalytic systems.
查看更多>>摘要：In this study, we designed and synthesized a 1% Fe-N-C nanotube (FeCNT) doped g-C3N4 (1%FeCNT@C3N4) to reduce the biotoxicity of g-C3N4 by reducing ROS generation and enhance its catalytic efficiency at the same time. The 1%FeCNT@C3N4 can not only effectively reduce the ROS generation at neutral pH but also had an extremely low electron-hole pairs recombination rate, which was attributed to the fact that O2 undergone a fourelectron oxygen reduction reaction (ORR) pathway at the Fe-N-C site. Additionally, the degradation results of tetracycline hydrochloride (TH) and Naproxen (NPX) by 1%FeCNT@C3N4 and g-C3N4 showed that the reaction rate constants of 1%FeCNT@C3N4 (0.0176 +/- 0.0012 min-1 and 0.05045 +/- 0.0010 min-1 for TH and NPX, respectively) were much higher than those of g-C3N4 (0.0098 +/- 0.0004 min-1 and 0.0281 +/- 0.0008 min-1 for TH and NPX, respectively). Moreover, the 1%FeCNT@C3N4 is proved to retain its high catalysis property in surface water.
Gao, KangIliuta, Maria C.Sahraei, Ommolbanin Alizadeh
20页
查看更多>>摘要：Application of coal fly ash (FA) residues as catalyst support is mainly restricted because of low surface area and high sulfur content. In the present work, the physicochemical properties of a low-efficiency FA were significantly improved via simple acid/alkali treatments consisting of one-step (HNO3 or NaOH) or two-step (NaOH/HNO3 or HNO3/NaOH) leaching-partial-dissolution (LPD). As a result, as compared to Ni-FA, the catalytic activity of the Ni-FA(treated) catalysts for glycerol steam reforming was considerably enhanced. Alkali-LPD is more effective than acid-LPD in simultaneously improving FA's surface area and regulating FA's elemental distribution. Ni-FA (HNO3/NaOH) has the best performance with high glycerol conversion to gas (99.2%) and H2 yield (74.5%), attributed to i) removal of sulfur-containing species by acid-LPD, ii) upgrading specific surface area, ironexposure, and Ni dispersion via alkali-LPD, iii) diminishment of coke using acid/alkali-LPD sequence treatment, and iv) enhancement of catalytic stability due to the formation of NiFe alloys.
查看更多>>摘要：When internally polarized by mechanical energy, piezoelectric materials can establish polarization electric field and provide driving force for separating photogenerated carriers. Herein, S vacancies are introduced as an intermediate to make metal ions form coordination bond with F- on PVDF (polyvinylidene fluoride) surface, and the built-in electric field is intimately related to polarized electric field. We successfully synthesized ZnS/Bi2S3-PVDF film photocatalyst containing S vacancies (ZnS-VS/Bi2S3-PVDF). Polarized electric field on PVDF caused by ultrasonic cavitation and built-in electric field formed between ZnS-VS/Bi2S3 heterojunction structure are beneficial to interfacial charge transferring. Theoretical calculation simulation demonstrate that the synergistic effect of the double electric fields is propitious to inhibit the recombination of carriers. The hydrogen evolution rate of ZnS-VS/Bi2S3-PVDF reaches 10.07 mmol h(-1) g(-1). Moreover, it has excellent reversibility and facile recovery capacity. This work provides new platform for photocatalytic reduction of hydrogen evolution and is expected to contribute to clean energy production.
查看更多>>摘要：CO2 cycloaddition reaction from propylene oxide and CO2 to cyclic carbonates is a desirable process to become carbon neutral. Photo energy can decrease the temperature and pressure needed for this reaction according to our previous results. However, the relationship between Lewis acidity and the photophysical process needs to be clarified and optimized. Hence, in this work, Zn is introduced into UiO-bpydc via the coordination of Zn with the bipyridyl group in bpydc. It is found that the introduction of Zn not only effectively activate propylene oxide, but also promote ligand to metal charge transfer (LMCT) process, which ultimately is beneficial for CO2 activation. However, Ce plays a negative effect under light irradiation. namely, the presence of Ce facilitates the energy transfer process rather than the LMCT process.
查看更多>>摘要：5-Hydroxymethylfurfural (HMF) synthesis from glucose over in-situ phosphated titania catalysts is presented. Phosphates were incorporated into titania framework forming a titanium phosphate surface layer, where the coordinatively unsaturated tetrahedral TiO4 units act as water-tolerant Lewis acid site (LAS) and the adjacent protonated phosphate as Bronsted acid site (BAS), together forming Lewis-Bronsted acid pairs at molecular-level proximity. Glucose turnover and HMF selectivity were enhanced due to the rapid fructose transfer from LAS to the adjacent BAS for its dehydration to HMF, facilitating LAS liberation for another glucose turnover. Reactions in a water-2-methyltetrahydrofuran biphasic system in packed-bed microreactors gave 66% HMF yield (from 1 M glucose at 150 degrees C), where the HMF space time yield is about two orders of magnitude higher than that in batch and the literature work. Phosphate leaching from the catalyst is rather limited, whereas the catalyst deactivated mainly by humin deposition and could be regenerated by calcination.
Nash, Connor P.Dupuis, Daniel P.Kumar, AnuragFarberow, Carrie A....
11页
查看更多>>摘要：The paraffin-to-olefin (P/O) ratio in gasoline fuel is a critical metric affecting fuel properties and engine efficiency. In the conversion of dimethyl ether (DME) to high-octane hydrocarbons over BEA zeolite catalysts, the P/O ratio can be controlled through catalyst design. Here, we report bimetallic catalysts that balance the net hydrogenation and dehydrogenation activity during DME homologation. The Cu-Zn/BEA catalyst exhibited greater relative dehydrogenation activity attributed to higher ionic site density, resulting in a lower P/O ratio (6.6) versus the benchmark Cu/BEA (9.4). The Cu-Ni/BEA catalyst exhibited increased hydrogenation due to reduced Ni species, resulting in a higher P/O ratio (19). The product fuel properties were estimated with an efficiency merit function and compared against finished gasolines and a typical alkylate blendstock. Merit values for the hydrocarbon product from all three BEA catalysts exceeded those of the comparison fuels (0-5.3), with the product from Cu-Zn/BEA exhibiting the highest merit value (9.7).
NSTL
Elsevier