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Hydroxyapatite (HAP) supported Rh, Fe, and Rh-Fe catalysts were prepared by impregnation, and the synergy effects between the catalyst and NTP (non-thermal plasma) on N2O catalytic decomposition were also investigated. CO2-TPD results show that HAP synthesized at high pH have a greater number of surface alkaline sites and promoted the adsorption of N2O. RhFe/HAP-11 catalyst exhibited 95.9% activity for the direct catalytic decomposition of N2O at 350 °C. Combining NTP with the RhFe/HAP-11 catalyst can significantly enhance the catalytic decomposition of N2O and greatly reduce the reaction temperature. The one-stage combination method enables the radicals generated by the plasma to participate in the reaction immediately on the catalyst surface, so it is more conducive to the N2O catalytic decomposition in the range of 150–200 °C. When NTP is applied, N2O conversion on RhFe/HAP-11 at 200 °C increases a lot from 7.1 to 90.0%. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA) is a promising membrane material for pervaporation (PV) desalination. However, the adjustment and control of the cross‐linking structure is still a challenge for PVA membrane. In this study, a novel pH‐resistant PVA‐based composite membrane for efficient pervaporation desalination was developed by precisely adjusting the cross‐linking behavior. Vinyl alcohol‐vinylamine copolymer (VA‐co‐VAm) containing both hydroxyl and amino groups was synthesized. Cross‐linking reaction was carried out based on the Schiff base reaction between amino groups (in VAm moiety) and glutaraldehyde (GA) under alkaline conditions. Cross‐linking degree of PVA selective layer was carefully controlled by adjusting the amino group content in copolymer. Results showed that membrane prepared with VA‐co‐VAm that containing 5 wt% N‐vinylformamide (NVF) displayed superior hydrophilicity and the largest free volume fraction. Pervaporation test indicated that the modified cross‐linking membrane showed good stability under extreme pH conditions. Specifically, under strong acid conditions (pH ~ 1) and alkaline conditions (pH ~ 14), the membrane showed excellent desalination performance with water flux over 12 kg/(m2 h), and the salt rejection higher than 99.95%. Based on the above results, the prepared membrane offers a promising platform for desalination under extreme pH conditions, which shows great potential in industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is a common greenhouse gas and urgent need to be contained. Direct catalytic decomposition of N2O by high activity catalyst into N2 and O2 is a low-cost and harmless method. Bimetallic catalysts show good catalytic activity in many classes of reactions, and plasma technologies, applied to prepare of catalyst, are considered to be a promising method. In our contribution, DBD cold plasma is applied to synthesize Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition. The influence of cobalt and rhodium content on N2O decomposition activity shows that the optimal amount of metal is determined as 5wt. % cobalt and 0.5wt. % rhodium loaded on Al2O3. The best working voltage is determined as 18kV. The results indicated that the Rh/Al2O3 catalysts prepared by atmospheric-pressure DBD cold plasma showed smaller size and high dispersion of Rh particles, so that the metal-support interaction and the catalytic activity are enhanced. Atmospheric-pressure DBD cold plasma is proved to be an environmentally friendly and efficient method for preparing high performance Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition.

The widely used dyes in the pharmaceutical, chemical, and medical industries have brought about an intensive concern for the sustainable development of the environment. Membrane separation offers a versatile method for classified recycling and the reuse of residual components. In this work, polyimide membranes were synthesized via the polymerization of 4,4′-(hexafluor-isopropylidene) diphthalic anhydride and 1,4-bis (4-aminophenoxy) benzene diamine. The organic solvent nanofiltration membrane was prepared by casting onto a glass plate and precipitating in the non-solvent phase. The properties of the membranes were recorded by FTIR, 1HNMR, TGA, and GPC. The molecular simulations were carried out to analyze the affinity between the membrane and different solvents. The membrane was used in the removal of Rose Bengal, methyl blue, Victoria blue B, and crystal violet from methanol. The effects of the feed liquid concentration, operating pressure, swelling degree, organic solvent resistance, and long-term running on the membrane performance were studied. Results showed that membranes prepared in this work demonstrated high solvent permeation and dye rejection due to the sieving effect and solvent affinity. For methyl blue, the solvent performance achieved a permeability of 2.18 L∙m−2∙h−1∙bar−1 corresponding to a rejection ratio of 94.2%. Furthermore, the membrane exhibited good stability over 60 h of continued testing. These results recommend a potential strategy in the development of a suitable monomer to prepare a polyimide membrane for dye separation. [ABSTRACT FROM AUTHOR]

To achieve a safe, efficient, and sustainable (even fully automated) production for the continuous‐flow hydrogenation reactions, which is among the most often used reactions in chemical synthesis, new catalyst types and immobilization methods as well as flow reactors and technologies have been developed over the last years; in addition, these approaches have been combined with new and transformational technologies in other fields such as artificial intelligence. Thus, attention from academic and industry practitioners has increasingly focused on improving the performance of hydrogenation in flow mode by reducing the reaction times, increasing selectivities, and achieve safe operation. This Minireview aims to summarize the most recent research results on this topic with focus on the advantages, current limitations, and future directions of flow chemistry. [ABSTRACT FROM AUTHOR]

In this study, Mg−Yb binary oxides were synthesized using different MgO concentrations and investigated for the catalytic dehydration of 1,4‐butanediol (BDO) into 3‐buten‐1‐ol (BTO). The physicochemical properties of the catalysts were characterized by N2 physisorption, X‐ray diffraction, Raman spectroscopy, temperature‐programmed techniques, and diffuse reflectance infrared Fourier transform spectroscopy. The Mg−Yb binary oxides exhibited superior catalytic activity and better BTO selectivity compared with the pristine Yb2O3 or MgO. Structures of Mg−O−Yb were generated in the binary oxides via the interchange of Yb or Mg in the MgO or Yb2O3 crystalline phases. Extra basic and acidic sites were formed over the Mg−Yb binary oxides because of the formation of surface defects and the presence of Mg−O−Yb structures, respectively. The acidic as well as basic sites were observed to influence the catalytic performance: BDO reactivity was enhanced by the more acidic sites, while BTO selectivity was favored by the basic sites. The highest BTO yield of 71.1 % was achieved over the Mg7Yb3 catalyst with 90.4 % BDO conversion and 78.6 % BTO selectivity at 350 °C. The in situ DRIFTS results indicated that BDO was first adsorbed on the catalyst and then reacted with the acidic sites to generate butoxides. The β‐H of the surface butoxides was abstracted by the basic oxygen anions to produce aldehyde species, which dissociated to form BTO. [ABSTRACT FROM AUTHOR]

A novel membrane/adsorption hybrid system was proposed for air prepurification in large scale air separation units. Mathematical models were established for cocurrent and countercurrent flow patterns with crude nitrogen as purge stream to describe the membrane separation performance. The experimental and predicted results are in good agreement confirming the validity of the mathematical models. Effects of membrane properties and operation parameters on O2 recovery, N2 recovery, and membrane area requirement were investigated. For countercurrent flow pattern, O2 recovery and N2 recovery were larger than 98 and 99%, respectively, and membrane area requirement was less than 0.25 m2/m3•h−1 with feed side pressure of 0.6 MPa and the purge gas/feed gas ratio of 0.2. [ABSTRACT FROM AUTHOR]

Well-homogenized RhFe alloy nanoparticles and core–shell structured Fe@Rh nanoparticles were highly dispersed on SBA-15 and then applied to N2O catalytic conversion. Compared to RhFe/SBA-15, Fe@Rh/SBA-15 showed a higher catalytic activity for N2O decomposition. This is because the Rh layers covering the Fe core were able to protect against oxidization and so Fe@Rh/SBA-15 was prevented from deactivating. DFT calculations were performed to study the reaction mechanism of N2O decomposition. The rate-determining step, which was found to be the formation of O2 from adsorbed oxygen atoms on the surfaces of RhFe and Fe@Rh, revealed that O atoms prefer to be adsorbed on exposed Fe atoms on the surface of RhFe rather than that of Fe@Rh. The calculation results indicate that the exposed Fe atoms tend to be oxidized on the surface of RhFe, resulting in the deactivation of RhFe/SBA-15 during the experiment. [ABSTRACT FROM AUTHOR]

The dibenzo-18-crown-6 derivatives such as di(nitrobenzo)-18- crown-6 and di(aminobenzo)-18-crown-6 were synthesized by nitration reaction and catalytic hydrogenation with high selectivity. The chemical structures were determined by FTIR, ¹H NMR, 13C NMR, and UV. Regarding the mixture of Ac2O and HNO3 as nitrating agent, the reaction exhibited commendable trans-isomer selectivity. Effects of nitrating agent ratio, reaction temperature and reaction time on yield of trans-di(nitrobenzo)-18-crown-6 were investigated. The yield of trans-di (nitrobenzo)-18-crown-6 was 62.9% for nitrating agent ratio of 1/1, reaction temperature of 50 °C and reaction time of 5 h. Moreover, effect of reaction time on trans-di(aminobenzo)-18-crown-6 was also studied. [ABSTRACT FROM AUTHOR]

The catalytic activity trends of four different metal surfaces (Rh, Pd, Pt and Ni) for N 2 O direct catalytic decomposition were analyzed and predicted using density functional theory (DFT). Some adsorption features on different metal surfaces were investigated, such as the structure, electron and energy of two important N 2 O adsorption sites: the top site and the flat-bidentate site. The DFT results show that the adsorption energy of N 2 O on the top site over Rh, Pd and Pt metal surfaces was negative, which indicates that N 2 O can be easily adsorbed on these metal surfaces. The difficulty of the N–O bond breakage in the flat-adsorbed N 2 O was analyzed by combining the molecular structure, density of state and charge density to predict the catalytic activity of different metal surfaces. The catalytic activity trend of different metal surfaces for N 2 O decomposition is determined as Rh > Pd > Pt > Ni, which is consistent with the corresponding experimental results. [ABSTRACT FROM AUTHOR]

WC-doped Ni over an active carbon catalyst (Ni–WC/AC), prepared by incipient wetness impregnation, is proposed as an anode for the amplified electrochemical oxidation of glucose in 0.1 M KOH solution. Cyclic voltammetry and morphology characterizations were used to explore these electrocatalysts. It was found that Ni–WC/AC catalysts were nanoparticles with a diameter of 10 nm and the 20%wtNi–20%wtWC/AC catalyst showed superior electrocatalytic activity toward glucose oxidation. The extraordinary activity obtained at the 20%wtNi–20%wtWC/AC modified glass carbon electrode (GCE) is attributed to the synergistic effect between Ni and WC toward glucose electroxidation. [ABSTRACT FROM AUTHOR]

Polyether based thin film composite (TFC) membranes were developed by interfacial polymerization (IP) on polysuylfone (PSf) ultra-filtration membrane with poly (dimethylsiloxane) (PDMS) inter-layer. Polyetheramine (PEA) and Trimesoyl Chloride (TMC) were selected as aqueous monomer and organic monomer, respectively. The thickness of the PDMS inter-layer was 550 nm, while IP separation layer was only 100 nm. The effects of the PDMS inter-layer and the PEA molecular weight on the TFC membrane performance were investigated. The gas permeation results show that the TFC membrane with PDMS inter-layer exhibits higher CO 2 /N 2 selectivity compared to the membranes without PDMS inter-layer. PDMS inter-layer is able to eliminate the defects on the support membrane and diminish the TMC hydrolysis as well. Among the membranes prepared with three different molecular weight PEAs (ED-600, ED-900 and ED-2003), the membrane of ED-900 exhibits the best performance with an impressive CO 2 permeance of 360 GPU and CO 2 /N 2 selectivity of 67.2 for a mixture CO 2 /N 2 (20/80 by volume), while for a mixture of CO 2 /CH 4 (10/90 by volume) it demonstrates CO 2 permeance of 275 GPU and CO 2 /CH 4 selectivity of 31.6. [ABSTRACT FROM AUTHOR]

4′,4″(5″) Di- tert-butyldibenzo 18-crown-6 (DTBB18C6) was successfully synthesized by SN2 with 4- tert-butyl catechol as starting material. Effects of reagents, solvents, and templates were investigated. Reaction process was monitored by the real-time online FTIR to study the actual reaction route. The highest DTBB18C6 yield (above 33%) was obtained by using Cs2CO3 as the template, 2,2′-diethylene glycol ditosylate as the reagent, and THF as the solvent. From the result of FTIR, four different reaction stages of DTBB18C6 synthesis process were proposed. [ABSTRACT FROM AUTHOR]

ABSTRACT A vinyl amine-vinyl alcohol copolymer (VAm-VOH) was synthesized through free-radical polymerization, basic hydrolysis in methanol, acidic hydrolysis in water, and an anion-exchange process. In the copolymer, the primary amino groups on the VAm segment acted as the carrier for CO2-facilitated transport, and the vinyl alcohol segment was used to reduce the crystallinity and increase the gas permeance. VAm-VOH/polysulfone (PS) composite membranes for CO2 separation were prepared with the VAm-VOH copolymer as a selective layer and PS ultrafiltration membrane as a support. The membrane gas permselectivity was investigated with CO2, N2, and CH4 pure gases and their binary mixtures. The results show that the CO2 transport obeyed the facilitated transport mechanism, whereas N2 and CH4 followed the solution-diffusion mechanism. The increase in the VAm fraction in the copolymer resulted in a carrier content increase, a crystallinity increase, and intermolecular hydrogen-bond formation. Because of these factors, the CO2 permeance and CO2/N2 selectivity had maxima with the VAm fraction. At an optimum applied pressure of 0.14 MPa and at an optimum VAm fraction of 54.8%, the highest CO2 permeance of 189.4 GPU [1 GPU = 1 × 10−6 cm3(STP) cm−2 s−1 cmHg−1] and a CO2/N2 selectivity of 58.9 were obtained for the CO2/N2 mixture. The heat treatment was used to improve the CO2/N2 selectivity. At an applied pressure of 0.8-0.92 MPa, the membrane heat-treated under 100°C possessed a CO2 permeance of 82 GPU and a CO2/N2 selectivity of 60.4, whereas the non-heat-treated membrane exhibited a CO2 permeance of 111 GPU and a CO2/N2 selectivity of 45. After heat treatment, the CO2/N2 selectivity increased obviously, whereas the CO2 permeance decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40043. [ABSTRACT FROM AUTHOR]