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Bioethanol, as a renewable energy source, is receiving continuous attention for efficient recovery in aqueous solution. In this work, high-permeable ethanol mix matrix membranes (MMMs) were prepared by incorporating covalent organic framework-300 (COF-300) into polydimethylsiloxane (PDMS) by solution blending. The morphology, functional groups, surface roughness, contact angle, and swelling degree of MMMs before and after COF-300 loading were characterized and analyzed. The encouraging finding is that the incorporation of porous COF-300 particles results in a significant enhancement of the hydrophobicity and ethanol affinity, which in turn increases the total flux and separation factor. The pervaporation results showed that the total flux reached 1515.28 g·m–2·h–1and the separation factor reached 8.7 at a 3 wt % COF loading. Compared with pure PDMS, the total flux and separation factor of MMMs increased by 71.4 and 7.8%, respectively. Primarily based on the unique pore structure characteristics of COF-300, it can provide ultrafast channels for ethanol molecules. At the same time, COF-300 itself is a porous hydrophobicity particle with good ethanol affinity, which will promote the diffusion of ethanol molecules, further promote membrane swelling, and thus increase the separation factor and flux. Moreover, the MMMs in this work exhibited satisfactory stability during 6 months of continuous operation. Therefore, COF-300 is expected to be an ideal filler material to improve the separation performance of permeable ethanol membranes.

As the ideal NO removal technology, the biggest challenge associated with the direct catalytic decomposition of NO is the development of highly active deNOx catalysts at low temperatures. Herein, a composite metal catalyst, Rh(0.2)/NC-MnFe, was prepared viaimpregnation for the low-temperature direct decomposition of NO, which exhibited 99.6% NO conversion and 63% N2selectivity at 150 °C, and nearly 100% NO conversion and 98% N2selectivity at 200 °C. The characterization results showed that the Rh(0.2)/NC-MnFe catalyst possessed a regular nanocage structure, good crystallinity, and suitable specific surface area. Its excellent low-temperature activity was attributed to the transfer of the dissociated O of NO from the Rh active site to the NC-MnFe support, which effectively inhibited the deactivation of Rh. The mechanism analysis indicated that NO adsorbed on the Rh(0.2)/NC-MnFe catalyst surface can generate NO2−and NO3−, and then the adsorbed NO together with NO3−is converted to NO2−species accompanied by the release of N2O. At last, NO2−is decomposed to N2.

In this study, a highly hydrophilic membrane was developed by an interfacial reaction using two aqueous monomers for pervaporation (PV) desalination. Two water-soluble monomers, procyanidin (PC) and vinyl alcohol-vinylamine copolymer (VA-co-VAm), were applied to prepare membranes on hydrophobic polyvinylidene difluoride (PVDF) membranes through interfacial reactions. Catechol groups of PC were oxidized to quinone groups under weakly alkaline conditions, which could react with amino groups of VA-co-VAm to form a cross-linked network. The PVDF membrane was first dipped into a PC aqueous solution to form a thin PC liquid layer on the surface. Accompanied by the PC liquid layer, the PVDF membrane was then dipped into the VA-co-VAm solution to induce the interfacial reaction. The composition and structure of membranes were observed, and the effects of different factors on the desalination performance were investigated. By applying two aqueous monomers in the interfacial reaction process, the obtained thin membrane showed good hydrophilicity with a water contact angle of less than 42°. A water flux of 42.16 kg/(m2·h) at 60 °C was obtained by treating a feed solution (3.5 wt % NaCl). At all testing procedures, the salt rejection remained higher than 99.99%. Besides, the membrane displayed superior stability over 48 h of testing. According to the above results, the prepared membranes showed great potential in the process of PV desalination. This work provides a new approach for highly permeable PV membrane preparation through an interfacial reaction using two water-soluble materials.

As one of the important atmospheric pollutants, the removal of NO in flue gas at low temperatures is still a severe challenge. Selective catalytic reduction (SCR) with urea is an effective method for NO removal at low temperatures. Herein, through directly loading urea, an Fe-modified Mn-based molecular sieve catalyst with good low-temperature urea-SCR activity was prepared by a stepwise impregnation method. The results show that with a mass ratio of Mn/Fe of 10:0.5 and a calcination temperature of 500 °C, the catalyst loaded with 15 wt % urea had the highest catalytic activity of 98.5% at 250 °C. Online mass spectrometry results show that NH3formed from the decomposition of urea reacts with NO when the temperature is above 150 °C, while urea directly reacts with NO below 150 °C. The density functional theory calculation demonstrates that the doping of Fe weakens the strength of the Mn–O bond in MnO2, which makes NO easier to combine with lattice oxygen to oxidize into NO2, thereby promoting the whole urea-SCR reaction. This work provides an overall perspective and theoretical support for the design of urea-SCR catalysts over a wide temperature range.

A carbon molecular sieve (CMS) membrane was prepared via a co-polyimide precursor containing a crown ether segment. Two elements ensured that the CMS membrane achieved both high permeability and selectivity: (1) preferential decomposition of the crown ether segment at relative low temperature and (2) the transformation of a pore structure from a micropore (>7 Å) to an ultra-micropore (<7 Å) at a higher-temperature pyrolysis. A BET analysis showed the CMS membrane formed a micropore below 500 °C. Then, the micropore structure gradually transformed to an ultra-micropore when the heat-treatment temperature raised to 500 and 650 °C, followed by formation of a single-distribution ultra-micropore pyrolyzed at 800 °C. The performance of membranes treated at 650 and 800 °C surpassed the 2015 upper bound for H2separation and the 2019 upper bound for CO2separation. Furthermore, the membrane treated at 650 °C exhibited remarkable mixed-gas separation performance and possessed a CO2permeability of 7266.4 ± 22.85 to 7496.3 ± 22.34 barrer and a CO2/N2(20/80, vol%) and CO2/CH4(10/90, vol%) selectivity of ∼60.

The key issues for the use of dibenzyltoluene (DBT) as a liquid organic hydrogen carrier (LOHC) are the high dehydrogenation temperature and the sluggish hydrogen releasing rate. Therefore, highly active catalysts are urgently needed for the dehydrogenation process. Towards an increased perhydro-dibenzyltoluene (H18-DBT) dehydrogenation rate, dielectric barrier discharge (DBD) plasma pretreatment was adopted to modify Pt/Al2O3catalysts. As revealed by various characterization methods, methyl, methylene and carboxylate groups were grafted on Al2O3and S2−and SO42−groups were grafted on Pt/Al2O3after DBD plasma treatment. The Pt dispersion, the different proportions of different crystal planes, the low coordinated Pt sites and hydrogen spillover on the catalyst surface were modified. The catalyst with carboxylate groups showed the highest dehydrogenation productivity and produced the least amount of by-products. These improvements in the catalysts' performance were confirmed and are attributed to the higher proportion of exposed Pt (1 1 1) and Pt (1 0 0) planes, fewer low coordinated Pt sites and more hydrogen spillover.

Membrane free volume is closely related to gas separation property. The free volume can be tuned by adjusting monomer structure for polyimide-based membrane materials, and then the gas separation property can be improved ulteriorly. In this work, crown ether (di(aminobenzo)-18-crown-6, DAB18C6)-based copolyimide membranes containing bulky and flexible diamine monomer (2,2′-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, HFBAPP) were synthesized for CO2separation. The −C(CF3)2– and −O– groups in HFBAPP can improve the membrane free volume and affinity with CO2, respectively. The microcavity size and fractional free volume of HFBAPP/DAB18C6/4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) membranes were investigated by molecular dynamics simulation and positron annihilation lifetime spectroscopy testing. The result showed that fractional free volume was improved obviously due to the presence of −C(CF3)2– in HFBAPP, while the microcavity size only showed very insignificant increase. Correspondingly, these membranes exhibited much higher CO2permeability and satisfied selectivity. Furthermore, the correlation between free volume and gas transport properties of crown ether-based copolyimide membranes was investigated to establish structure–property relationship. CO2/CH4and CO2/N2mixed-gases separation properties of HFBAPP/DAB18C6/6FDA exceeded 2008 Robeson’s upper bounds.

Mixed matrix membranes (MMMs) could combine the advantages of both polymeric membranes and porous fillers, making them an effective alternative to conventional polymer membranes. However, interfacial incompatibility issues, such as the presence of interfacial voids, hardening of polymer chains, and blockage of micropores by polymers between common MMMs fillers and the polymer matrix, currently limit the gas separation performance of MMMs. Ternary phase MMMs (consisting of a filler, an additive, and a matrix) made by adding a third compound, usually functionalized additives, can overcome the structural problems of binary phase MMMs and positively impact membrane separation performance. This review introduces the structure and fabrication processes for ternary MMMs, categorizes various nanofillers and the third component, and summarizes and analyzes in detail the CO2separation performance of newly developed ternary MMMs based on both rubbery and glassy polymers. Based on this separation data, the challenges of ternary MMMs are also discussed. Finally, future directions for ternary MMMs are proposed.

Polycyclic aromatic hydrocarbons (PAHs) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of their high hydrogen storage, easy transportation, low price, and other advantages. Dehydrogenation is the key point of the PAH hydrogen storage. However, the dehydrogenation reaction rate of perhydro-PAHs is slow, and their pathway is still not clear. To clarify the PAH dehydrogenation pathway, three kinds of perhydro-PAHs containing six-membered rings (methylcyclohexane, perhydro-diphenylmethane, and perhydro-dibenzyltoluene) are selected, and their dehydrogenation processes over the Pt/Al2O3catalyst are carried out by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). It was found that the dehydrogenation in the six-membered ring started in the para position of the −CH3group, and then, the six-membered ring was transformed into a benzene ring gradually. Between the six-membered rings, dehydrogenation started from the side ring, which has fewer groups.

Ethanol separation via the pervaporation process has shown growing application potential in solvent recovery and the bioethanol industry. In the continuous pervaporation process, polymeric membranes such as hydrophobic polydimethylsiloxane (PDMS) have been developed to enrich/separate ethanol from dilute aqueous solutions. However, its practical application remains largely limited due to the relatively low separation efficiency, especially in selectivity. In view of this, hydrophobic carbon nanotube (CNT) filled PDMS mixed matrix membranes (MMMs) aimed at high-efficiency ethanol recovery were fabricated in this work. The filler K-MWCNTs was prepared by functionalizing MWCNT-NH2with epoxy-containing silane coupling agent (KH560) to improve the affinity between fillers and PDMS matrix. With K-MWCNT loading increased from 1 wt % to 10 wt %, membranes showed higher surface roughness and water contact angle was improved from 115° to 130°. The swelling degree of K-MWCNT/PDMS MMMs (2 wt %) in water were also reduced from 10 wt % to 2.5 wt %. Pervaporation performance for K-MWCNT/PDMS MMMs under varied feed concentrations and temperatures were evaluated. The results supported that the K-MWCNT/PDMS MMMs at 2 wt % K-MWCNT loading showed the optimum separation performance (compared with pure PDMS membranes), with the separation factor improved from 9.1 to 10.4, and the permeate flux increased by 50% (40–60 °C, at 6 wt % feed ethanol concentration). This work provides a promising method for preparing a PDMS composite with both high permeate flux and selectivity, which showed great potential for bioethanol production and alcohol separation in industry.

Pt-Ni bimetallic catalysts and the corresponding monometallic Pt catalysts supported on active carbon were prepared by incipient wetness impregnation and characterized by X-ray diffraction, N2adsorption, and NH3-temperature programmed desorption. Their activities for decalin dehydrogenation were investigated at a superheated liquid film state in a batch reactor. The effects of temperature, impregnation sequence, and Pt/Ni molar ratio on the dehydrogenation activity and the naphthalene yield were investigated. The results show that the Pt-Ni bimetallic catalyst significantly enhanced hydrogen evolution compared with either Ni or Pt monometallic catalyst. The highest dehydrogenation conversion and naphthalene yield were obtained when the Pt/Ni molar ratio was 1:1 and Pt was impregnated first. The experimental results were correlated with density functional theory calculations of hydrogen binding energy (HBE) on different catalytic surfaces. The correlation confirmed that bimetallic surfaces with stronger HBEs had higher dehydrogenation activities.

Nickel-rich LiNi0.8Co0.1Mn0.1O2(NCM811) with respect to Li metal can enhance the energy density of lithium batteries effectively. However, the unstable Li deposition, together with the dissolution and migration of transition metal (TM) ions toward the anode deteriorate the cycle performance of NCM811||Li battery, especially when commercial carbonate electrolyte is used. Herein, tris(trimethylsilyl)phosphite (TMSPi) and fluoroethylene carbonate (FEC) are used to construct a dual-additive electrolyte, by which both electrodes can be protected. It is found that TMSPi can be preferentially adsorbed on the cathode surface through its strong coordination with Ni4+, playing the role as a HF scavenger and suppressing TM ions dissolution, as well as mitigating the structural degradation of the cathode effectively. When it comes to the lithium anode, the presence of TMSPi may lead to side reactions with Li metal, accompanied by fast dendrite growth. The introduction of FEC could facilitate the formation of stable electrode/electrolyte interfaces on both sides. Particularly, reduce the direct contact between TMSPi and Li anode, thus ameliorate the incompatibility issue. Consequently, the NCM811||Li cell with dual-additive demonstrates excellent capacity retention of 81.2% after 500 cycles at 1 C rate. As a sharp contrast, it only retains 13.9% in the one with blank electrolyte. The findings of this work provide a new insight into enhancing the cycle performance of NCM811||Li system via the synergistic effect between additives.

Fixed‐carrier composite hollow‐fiber membranes were prepared with polyvinylamine (PVAm) as the selective layer and a polysulfone ultrafiltration membrane as the substrate. The effects of the PVAm concentration in the coating solution, the number of coatings, and the crosslinking of glutaraldehyde and sulfuric acid on the CO2 permeation rate and CO2/CH4 selectivity of the composite membranes were investigated. As the PVAm concentration and the number of coatings increased, the CO2/CH4 selectivity increased, but the CO2 permeation rate decreased. The membranes crosslinked by glutaraldehyde or sulfuric acid possessed higher CO2/CH4 selectivities but lower CO2 permeation rates. For the pure feed gas, a composite hollow‐fiber membrane coated with a 2 wt % PVAm solution two times and then crosslinked with glutaraldehyde and an acid solution in sequence had a CO2 permeation rate of 3.99 × 10−6 cm3 cm−2 s−1 cmHg−1 and an ideal CO2/CH4 selectivity of 206 at a feed gas pressure of 96 cmHg and 298 K. The effect of time on the performance of the membranes was also investigated. The performance stability of the membranes was good during 6 days of testing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1885–1891, 2006

Poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate) (VSA–SA)/polysulfone (PS) composite membranes were prepared for the separation of CO2. VSA–SA contained secondary amines and carboxylate ions that could act as carriers for CO2. At 20°C and 1.06 atm of feed pressure, a VSA–SA/PS composite membrane displayed a pure CO2 permeation rate of 6.12 × 10−6 cm3(STP)/cm2 s cmHg and a CO2/CH4 ideal selectivity of 524.5. In experiments with a mixed gas of 50 vol % CO2 and 50 vol % CH4, at 20°C and 1.04 atm of feed pressure, the CO2 permeation rate was 9.2 × 10−6 cm3 (STP)/cm2 s cmHg, and the selectivity of CO2/CH4 was 46.8. Crosslinkages with metal ions were effective for increasing the selectivity. Both the selectivity of CO2 over CH4 and the CO2 permeation rate had a maximum against the carrier concentration. The high CO2 permeation rate originated from the facilitated transport mechanism, which was confirmed by Fourier transform infrared with attenuated total reflectance techniques. The performance of the membranes prepared in this work had good stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 275–282, 2006

4′,4′′(5′′)-Di-tert-butyldibenzo-18-crown-6 (DTBB18C6) was synthesized by improving the electrophilic aromatic substitution of dibenzo-18-crown-6 (DB18C6) using tert-butyl alcohol (TBA) as alkylation reagent, H3PO4(85 wt %) as catalyst and CH2Cl2as solvent. Experimental results show that the optimized reaction conditions were 0.03 mol L−1for TBA concentration, 2.5 for TBA/DB18C6 molar ratio, 0.006 mol L−1for H3PO4concentration, 50 °C reaction temperature, and 6 h reaction time. Under the optimum reaction conditions, DTBB18C6 yield can reach 43.65%.