The 50 most-cited articles in Industrial & Engineering Chemistry Research, 2017

Graphene is considered as one of the most promising materials in a wide range of applications because of its outstanding electronic, optical, thermal, and mechanical properties. Given its large specific surface area, two-dimensional structure, facile decoration, and high adsorption capacity, numerous graphene-based nanomaterials with unprecedented characteristics have been designed, prepared, and applied in catalysis. In this article, we first reviewed common synthetic methods to prepare graphene-based catalysts followed by critical comments and possible solutions. We then briefly summarized the characterization techniques that were relevant to catalysis applications and their applications in energy conversion, environmental protection, and several other typical fields. Finally, we discussed the challenges and opportunities for the future development of graphene-based nanomaterials in sustainable catalysis. This review provides key information to the catalysis community to design and fabricate graphene-based novel nanomaterials with great performance.

Fibrillar and particulate structure magnetic carbons (MCFs and MCPs) were prepared from the same precursor (polyacrylonitrile and Fe(NO 3 ) 3 ·9H 2 O) by using a different method, displaying a significant morphology dependence on wastewater treatment. TEM, SEM, XPS, TGA, etc. were systematically carried out to characterize the carbon samples to verify the morphology difference between these two kinds of carbon adsorbents. The results demonstrated that, along with the increase of the Fe(NO 3 ) 3 ·9H 2 O loading in the precursor from 10 to 40 wt %, the fibrillar nanoadsorbents displayed an improved activity from 12.6% to 51.4% Cr(VI) removal percentage with the initial Cr(VI) concentration at 4 mg/L. For the maximum removal capacity, the fibrillar sample (MCFs-40) demonstrated 3 times higher removing capacity (43.17 mg/g) than that of particulate nanoadsorbents (MCPs-40, 15.88 mg/g) for the Cr(VI) removal with pH at 1, demonstrating that the fibrillar sample was more favorable for the wastewater treatment than particulate sample. This enhanced removal was mainly attributed to higher…

The xylene isomers p -xylene, o -xylene, and m -xylene are aromatic hydrocarbons comprising with two methyl groups located at different positions on a benzene ring. The mixture originates from catalytic reforming of crude oil, and each individual isomer acts as a valuable intermediate; however, similar physicochemical properties make their separation difficult. This Review focuses on materials employed for their separation, such as metal–organic frameworks, molecular sieves, organics, and graphene quantum dots. Recent advances in separation of xylene isomers are summarized, including adsorption, membrane, and chromatographic separation techniques, and adsorption capacity and selectivity combined with mechanisms of separation are discussed.

Heavy metal ions of Pb(II) and Cd(II) have become the global health and environmental concerns. NH 2 -functionalized Zr-MOFs were prepared via a rapid microwave-promoted synthesis and first used in the adsorptive removal of both Pb(II) and Cd(II). The nanosized (<100 nm) Zr-MOFs had an XRD pattern of UiO-66-NH 2 . Effects of adsorption time, temperature, pH, and initial ions concentration were studied on the adsorption of Pb(II) and Cd(II) onto the Zr-MOFs. The absorption results showed that the removal of Pb(II) was 99.95% after 120 min at temperature of 30 °C and pH of 6 with an initial concentration of 10 mg·L –1 . And the adsorption capacity of Cd(II) achieved 177.35 mg·g –1 at an initial concentration of 40 mg·L –1 . The adsorption fit the pseudo second-order kinetic model well and the mechanism was confirmed mainly as a coordination interaction between the amino group (−NH 2 ) and Pb(II) or Cd(II). The NH 2 -functionalized Zr-MOFs have been proven to show good performance in the removal of heavy metal ions as an efficient adsorbent.

A novel flame retardant (FR) DOPO-PEPA, which was synthesized via Atherton–Todd reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane (PEPA), was used as an additive-type FR in epoxy resin (EP). The results of the limiting oxygen index (LOI), vertical burning test, and cone calorimeter test indicated that the flame retardance of FR-EP composites is dependent on the chemical structure of phosphorus-based FRs. EP/DOPO-PEPA shows pretty good mechanical properties and a relatively high degree of cross-linking. Furthermore, the synergy as DOPO-PEPA was more efficient than that of DOPO or PEPA alone to flame retardant EP. When the FR additives were 9.1%, the EP/DOPO-PEPA acquired a LOI value of 35%, UL94 V-0 rating, and the lowest peak of heat release rate (PHRR) of 595 kW/m 2 . Furthermore, its continuous and firm char residue layer also reinforced this kind of action.

Solidified natural gas (SNG) is a promising option to store natural gas in the form of clathrate hydrates because of several benefits offered that include high degree of safety, eco-friendliness, high volumetric storage capacity, and the relative ease of gas recovery. Environmentally benign amino acids have been reported as promising kinetic promoters for enhancing methane hydrate formation. In this work, we examine in detail the effect of three different types of amino acids—tryptophan (nonpolar, hydrophobic amino acid with aromatic side chain), histidine (polar, basic amino acid with aromatic side chain), and arginine (polar, basic amino acid with aliphatic side chain)—on the kinetics of methane hydrate formation. The effect of amino acid concentration on the hydrate formation kinetics was investigated in two reactor configurations, namely, stirred and unstirred tank reactors. Amongst the amino acids studied, the best kinetic promotion for methane hydrate formation (in both stirred and unstirred reactor configurations) was achieved by tryptophan. The optimal concentration for best…

In this work, iron-based and cobalt-based metal–organic frameworks (MOFs) were successfully synthesized by a facile solvothermal method. The obtained MOFs were added into polystyrene (PS) as flame retardants for the first time. The results of thermal gravimetric analysis and cone calorimetry indicated the addition of MOFs significantly enhanced the thermostability and flame retardancy of the PS composites. Compared with that of neat PS, greater than 14% and 28% decreases in the peak heat release rate were observed for PS/Fe-MOF and PS/Co-MOF, respectively, suggesting a flame retardant effect of MOFs. Based on thermogravimetric analysis–infrared spectrometry results and the analysis of combustion residues, the possible mechanism of the enhanced thermostability and flame retardancy of the PS composites was proposed as the combination of thermal barrier effect and catalytic effect of MOFs, which would allow promising application in the development of fire safety polymer materials.

Abstract An effective microwave-assisted process for recycling low-density polyethylene (LDPE) waste into value-added chemicals was developed. To achieve fast and effective oxidative degradation aimed at production of dicarboxylic acids, nitric acid was utilized as an oxidizing agent. Different conditions were evaluated, where recycling time and concentration of oxidizing agent were varied and the end products were characterized by FTIR, NMR, and HPLC. After just 1 h of microwave irradiation at 180 °C in relatively dilute nitric acid solution (0.1 g/mL), LDPE powder was totally degraded. This transformation led to few well-defined water-soluble products, mainly succinic, glutaric, and adipic acids, as well as smaller amounts of longer dicarboxylic acids, acetic acid, and propionic acid. The length of the obtained dicarboxylic acids could to some extent be tuned by adjusting the reaction time, temperature, and amount of oxidizing agent. Finally, the developed process was verified by recycling LDPE freezer bags as model LDPE waste. The freezer bags were converted mainly into…

This work aims to improve the rheological properties of partially hydrolyzed polyacrylamide (HPAM) for enhanced oil recovery by using silica (or silicon dioxide, SiO 2 ) nanoparticles (NPs). Novel aqueous HPAM-based SiO 2 nanocomposites were formulated, and their rheological properties were investigated under different salinities, temperatures, and aging times. The results show that the inclusion of silica NPs significantly improved the viscosity and viscoelastic properties of HPAM especially under high temperature and high salinities. The NP/HPAM hybrid showed an impressive thermal stability at T = 80 °C after 12 days, and the viscosity reached ∼5 times that of HPAM at 0.8 wt % NP loading. The Fourier transform infrared spectral data confirmed that the formation of a hydrogen bond between the carbonyl groups in HPAM and the silanol functionalities on the surface of silica NPs contributed to the improved performance. The oscillation test indicated that seeding SiO 2 remarkably facilitated the cross-links among polymer molecules and made the hybrids more elastically dominant. For a…

Despite extensive studies on the steam reforming of model compounds (e.g., ethanol), steam reforming of real bio-oil is a more practical means for H 2 production. This review summarizes recent advances made in steam reforming of real bio-oil, with an emphasis on catalyst development for the process. Among the catalysts investigated, Ni is shown to be promising given its high activity for C–C and C–H bond cleavage. It also has the added advantage of a low cost of production. Strategies to improve catalyst performance include the mitigation of carbon deposition, inhibition of methanation, as well as promotion of water gas shift reactions. In addition, a discussion on current understanding of the reaction mechanism and catalyst deactivation is included in this review, with the aim to provide insight into the relationship between catalyst structure and performance that will give direction toward the development of high performance bio-oil steam reforming catalysts.

Abstract Equations of state (EoS) are essential in the modeling of a wide range of industrial and natural processes. Desired qualities of EoS are accuracy, consistency, computational speed, robustness, and predictive ability outside of the domain where they have been fitted. In this work, we review present challenges associated with established models, and give suggestions on how to overcome them in the future. The most accurate EoS available, multiparameter EoS, have a second artificial Maxwell loop in the two-phase region that gives problems in phase-equilibrium calculations and excludes them from important applications such as treatment of interfacial phenomena with mass-based density functional theory. Suggestions are provided on how this can be improved. Cubic EoS are among the most computationally efficient EoS, but they often lack sufficient accuracy. We show that extended corresponding state EoS are capable of providing significantly more accurate single-phase predictions than cubic EoS with only a doubling of the computational time. In comparison, the computational time of…

Commercial nanofiltration (NF) membranes have been used to separate dyes and salts in industry; however, NF membrane’s high rejection to divalent salts (i.e., Na 2 SO 4 ) leads to a reduction of salt recovery. In this study, a tight ultrafiltration (t-UF) ceramic membrane (MWCO 8800 Da) is proposed to fractionate dyes and mixed salts (NaCl/Na 2 SO 4 ) for textile wastewater treatment. Performance of the t-UF ceramic membrane and DK polymeric membrane (from GE) has been compared regarding to permeability, retention of reactive dyes, and permeation of salts. The t-UF ceramic membrane presents better permeability, competitive rejection of dye molecules (>98%), and reduced rejection of NaCl (<10%) and Na 2 SO 4 (<30%) in comparison with DK membrane; the pure water permeability of t-UF membrane is at least 6 times that of DK membrane. In particular, the operation parameters (TMP, temperature, and pH) and solution environment (concentration and charges) have been intensively evaluated for dye/dual-salts separation efficiency in the membrane process. It also reveals that the t-UF ceramic…

In situ and operando spectroscopic techniques are crucial for our understanding of complex heterogeneously catalyzed reactions. Under actual reaction conditions, however, many phenomena such as adsorption, (by)-product formation, and desorption of various species in different phases occur simultaneously, leading to crowded spectra that are difficult to interpret. About 15 years ago, modulation excitation spectroscopy (MES) was introduced to the heterogeneous catalysis community and has been increasingly applied since then. The periodic perturbation of a given system, in combination with phase-sensitive detection (PSD) analysis, significantly reduces noise, distinguishes between active and spectator species, and enables extraction of kinetic information. In this review article, we discuss the origin and theory of MES, summarize different application examples (with an emphasis on heterogeneous catalysis), and suggest future developments of the technique.

It has been known for decades that high performances for explosives (as characterized by detonation velocity D, detonation pressure P, or Gurney energy E G ) are connected with high impact sensitivities, i.e., low values of the drop weight impact height h 50 . This trade-off is theoretically substantiated for the first time. It stems from the primary role of the amount of chemical energy evolved per atom for both performance and sensitivity. Under realistic assumptions, log( h 50 ) increases linearly with D –4 or equivalently with P –2 or E G –1 . This prediction proves consistent with experimental data for nonaromatic nitro compounds. The occurrence of different explosophores on the same molecule is suggested as a factor influencing the performance-sensitivity trade-off. Finally, it is shown that a large body of data may be explained by the present approach, which naturally integrates thermodynamic (energy content) as well as kinetic (activation energies) aspects. This model should help in designing powerful high energy compounds with acceptable sensitivity.

Cu x Ni 100– x ( x = 0, 20, 40, 60, 80, and 100) nanoparticles were uniformly grown on the surface of CeO 2 by the liquid impregnation method. The as-prepared nanocomposite abbreviated Cu x Ni 100– x –CeO 2 was characterized by various techniques including, X-ray powder diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface area analyzer, and transmission electron microscopy. The catalytic activity of Cu x Ni 100– x –CeO 2 nanocomposites was investigated in 4-nitrophenol (4-NP) reduction reaction. Among the synthesized nanocomposites, Cu 60 Ni 40 –CeO 2 exhibited the best catalytic activity (rate constant as 0.1654 s –1 ) with high recyclability for five consecutive runs. The mechanism of the reduction was studied, and the adsorption equilibrium constant of 4-NP ( K 4-NP ) and borohydride ( K BH 4 – ) was calculated by using the Longmuir–Hinshelwood model. The energy of activation ( E a ) and thermodynamic parameters such as activation enthalpy (Δ H ⧧ ), entropy (Δ S ⧧ ), and Gibbs free energy (Δ G ⧧ ) have also…

Kinetics of methanol synthesis from carbon dioxide hydrogenation is studied on two noncommercial catalysts: a copper–zinc oxide catalyst on alumina (CuZA) and a copper–zinc oxide catalyst on zirconia (CuZZ). The experiments have been performed in an isothermal fixed bed reactor with a temperature range between 200 and 230 °C, a total pressure comprised between 50 and 80 bar, a gas hourly space velocity (GSHV) between 7800 and 23 400 h –1 and for different hydrogen:carbon dioxide molar ratios (between 2 and 6). Unlike other works in the literature, no carbon monoxide is contained in the feed which corresponds to the conditions of some recent industrial applications, the influence of the catalyst support has been tested to improve the methanol selectivity. The experimental data were modeled using the kinetic laws and adsorption coefficients determined by Graaf et al. based on a Langmuir–Hinshelwood–Hougen–Watson (LHHW) mechanism. The reactor model was based on an isothermal pseudo-homogeneous plug flow model without mass-transfer limitations. An optimization procedure was performed in…

Industrial and nanometallic catalysts are composed of an active component of metallic nanoparticles tailored by one or more additives and/or other metals, which should be in interaction and highly dispersed on a support. Therefore, it is a tough challenge to design and prepare such complicated catalysts. One promising way involves using perovskite-type oxides (PTOs, or written as ABO 3 according to the composition) as the catalyst precursors. That is the subject of this Review, with the aim to provide inspiration for designing and developing supported metallic nanocatalysts. The contents include ABO 3, partially substituted ABO 3 (A 1- y A′ y BO 3, AB 1- x B′ x O 3, and A 1- y A′ y B 1- x B′ x O 3 ), and PTOs supported on a support as the catalysts precursors. In PTOs, transition metal ions at A, A′, B, and B′ sites are confined in a PTO crystallite, and those ions are mixed uniformly at the atomic level, which is the basis for using PTOs as the precursors.

In this work, we perform a comparative techno-economic and environmental analysis for manufacturing ethylene and propylene from naphtha and from shale gas with rich natural gas liquids (NGLs). We first propose two novel process designs for producing ethylene and propylene from NGLs-rich shale gas. These two designs employ steam co-cracking of an ethane–propane mixture and an integration of ethane steam cracking and propane dehydrogenation, respectively. For benchmarking, we also consider a conventional process design in which ethylene and propylene are produced via steam cracking of naphtha. Detailed process models are developed for all the three designs to obtain the mass and energy balances of each unit operation. On this basis, techno-economic analysis and life cycle analysis are conducted for each of the three designs in order to systematically compare the production costs and life cycle environmental impacts of ethylene and propylene manufactured from shale gas and naphtha based on the same conditions. The economic analysis indicates that manufacturing ethylene and propylene…

We report the first comprehensive review of the industrial process for the catalytic partial oxidation of methanol to formaldehyde using silver catalyst. Formaldehyde remains a key, large volume industrial chemical which is ubiquitous to household, commercial, aviation, pharmaceutical and automotive products due to its high reactivity and versatility. Critical analysis of the various technological approaches used to manufacture formaldehyde, characteristics of silver catalysts employed, process conditions, and performance values has been presented. The three common plant types are almost complete conversion (BASF type); incomplete conversion followed by distillation (ICI type); and the off-gas recycle process which dominates world production due to its extensive use in China. Polycrystalline silver remains the most popular catalyst, with only minimal use of alternate supported catalysts or gauze materials. Catalyst physical properties such as bulk density, purity, mechanical strength, size fraction and shape are important in relation to overall formaldehyde synthesis performance.…

This paper develops a methodology to combine diagnostic information from various fault detection and isolation tools to diagnose the true root cause of an abnormal event in industrial processes. Limited diagnostic information from kernel principal component analysis, other online fault detection and diagnostic tools, and process knowledge were combined through Bayesian belief network. The proposed methodology will enable an operator to diagnose the root cause of the abnormality. Further, some challenges on application of Bayesian network on process fault diagnosis such as network connection determination, estimation of conditional probabilities, and cyclic loop handling were addressed. The proposed methodology was applied to Fluid Catalytic Cracking unit and Tennessee Eastman Chemical Process. In both cases, the proposed approach showed a good capability of diagnosing the root cause of abnormal conditions.

The integration of nanometer-sized fillers into polymer matrices to create nanocomposite materials has attracted a great deal of interest, not only because these materials can be tailored to specific practical applications but also because they can exhibit synergistic combinations of properties that display multifunctionality. Herein, we successfully incorporated silica (SiO 2 ) nanoparticles into the rubber-modified polybenzoxazine (PBZ) by mixing and applied as a nanocomposite coating that exhibits both superhydrophobicity and superoleophilicity through a facile dipping and spraying technique. We used PBZ, not only because of its near-zero shrinkage upon polymerization, chemical resistance, and good dielectric, thermal, and mechanical properties but also because, most importantly, of its low surface free energy and low water absorptivity. With superhydrophobicity coexisting with superoleophilicity in one material, potential anticorrosion, anti-ice, and organics/water separation applications of the coating were investigated. Results revealed that the rubber-modified PBZ coating…

Metal–organic frameworks represent a class of microporous adsorbents with high application potential for adsorption heat transformation. Here, we present a functional, full-scale heat exchanger coated with the microporous aluminum fumarate MOF Basolite A520 using a polysiloxane-based binding agent. The function of the heat exchanger was evaluated resulting in a gross cooling power of 2900 W (at the beginning of the adsorption cycle) or, respectively an average cooling power of 690 W (up to a limit of 90% equilibrium loading in 7 min) under the working conditions of a realistic adsorption chiller of 90 °C – 30 °C – 18 °C (temperature level of heat source, heat rejection/condenser, and evaporator).

Nano metal–organic frameworks (ZIF-8) particles were synthesized, and poly(lactic acid) (PLA)/ZIF-8 nanocomposite films were prepared by solution-blending and film-casting methods. The addition of nano ZIF-8 particles improved the mechanical properties and had an impact on the crystallization of PLA. The electrical properties of the PLA/ZIF-8 nanocomposites were found to be dependent on the frequency and the ZIF-8 content. The prepared PLA/ZIF-8 films had good transparency even as the content of the nano ZIF-8 particles reached 3 wt %. Compared with 21.5% of pure PLA, the limited oxygen index value of the nanocomposite film containing 1 wt % ZIF-8 reached 26.0%. Therefore, it is proposed that the prepared nanocomposites can be used as the substrates and dielectric to make disposable electronics. The char residues after burning were studied in detail by scanning electron microscopy and Raman and X-ray photoelectron spectroscopies, and the flame retardant mechanism was also discussed.

The promoting effect of alkali nitrates molten salt on the CO 2 capture capacity of a commercial MgO was investigated in detail. In particular, the ratio of Li/Na/K nitrates and the loading of the molten salt mixture on the MgO particles were optimized, and the influence of calcination and adsorption temperatures was evaluated. The MgO sample doped with 10 mol % (Li 0.3 Na 0.6 K 0.1 )NO 3 was demonstrated to possess the highest CO 2 uptake (up to 16.8 mmol g –1 ), which is the highest value reported for MgO based adsorbents in the literature. The CO 2 adsorption/desorption cycling stability was studied using both temperature swing adsorption (TSA) and pressure swing adsorption (PSA). The morphology and structure of the optimized adsorbent, 10 mol % (Li 0.3 Na 0.6 K 0.1 )NO 3 ·MgO, were characterized thoroughly using XRD, SEM, FTIR, and BET analyses. The thermal stability of doped alkali nitrates was investigated via temperature program desorption and XRD analysis, which indicated that the phase status of the molten salts is crucial for the marked improvement in CO 2 capture capacity…

Globally, liquefied natural gas (LNG) has drawn interest as a green energy source in comparison with other fossil fuels, mainly because of its ease of transport and low carbon dioxide emissions. However, LNG production is an energy and cost intensive process because of the huge power requirements for compression and refrigeration. Therefore, a major challenge in the LNG industry is to improve the energy efficiency of the LNG processes through economic and ecological strategies. Optimizing the design and operational parameters of the natural gas liquefaction cycles has been considered as one of most effective and popular approaches to address this issue. This paper reviews recent developments in the design optimization of LNG processes. In the choice of the most suitable and competitive LNG process, the operating costs, capital costs, environmental impact, and safety concerns must be considered for the optimal design and operation of LNG processes. The challenges in comparing recent researches are also discussed, along with suggestions for future directions to improve the energy…

In this Article, a new electrochemical sensor based on molecular imprinting polymer (MIP) and platinum nanoparticles (Pt NPs)/carbon nitride nanotubes (C 3 N 4 NTs) nanocomposite was developed for atrazine (ATR) analysis. First, the structures of prepared nanocomposites and surfaces were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). After the characterization studies, ATR-imprinted glassy carbon electrode (GCE) based on Pt NPs/C 3 N 4 NTs nanocomposite was developed by 100 mM phenol containing 25 nM ATR. The linearity range and the detection limit of the molecular imprinted sensor were calculated as 1.0 × 10 –12 –1.0 × 10 –10 and 1.5 × 10 –13 M, respectively. In addition, the voltammetric sensor was applied to wastewater samples with high recovery.

Vitrimers were created from a commercial high-performance anhydride-cured epoxy in the presence of various metal transesterification catalysts. Compressive creep strains greater than 50% were observed in samples containing dibutyltin diacetate or dibutyltin bis(2,4-pentanedionate) via a compression set experiment. Stress relaxation experiments were carried out in a parallel plate geometry and analyzed with a newly modified exponential model proposed to better describe the relaxation process. The results demonstrate that it is not only possible to realize reworkability on relatively short time scales (hundreds of seconds) without compromising the mechanical properties of these networks at elevated temperatures but that, with proper catalyst selection, this may be accomplished with negligible activity under curing conditions. This effort also highlights differences in the behavior of different transesterification catalysts in this context. The approach to the selection and analysis of the materials reported here has implications for the design of new vitrimers more generally.

Various single and blended amines (namely, MEA(monoethanolamine), MEA-DEEA (2-diethylamino ethanol), MEA-MDEA (methyldiethanolamine), MEA-1DMA2P (1-dimethylamino-2-propanol)) with three types of catalysts (H-ZSM-5, MCM-41 and SO 4 2– /ZrO 2 ) were studied to determine the respective roles of catalyst and solvent in heat duty and CO 2 desorption rate with an initial CO 2 loading of 0.5 mol CO 2 /mol amine at 371 K. The results show that performance of the three catalysts in all the four investigated aqueous solution systems followed the trend: H-ZSM-5 > MCM-41 > SO 4 2– /ZrO 2 . These results highlight the fact that even though HZSM-5 has moderate acidic sites as compared to MCM-41 and SO 4 2– /ZrO 2, its large B/L acid sites ratio coupled with mesopore surface area had the best performance. Furthermore, based on this study, the blended system of aqueous 5 M MEA+1 M MDEA with H-ZSM-5 provided the best approach for solution regeneration because the strong electron withdrawing chemical structure of MDEA.

A novel all-solid-state RGO/g-C 3 N 4 /BiVO 4 Z-scheme heterostructure was prepared using a facile hydrothermal method. The as-obtained RGO/g-C 3 N 4 /BiVO 4 Z-scheme heterostructure exhibited enhanced photocatalytic activity toward the degradation of tetracycline hydrochloride under visible-light irradiation, which was about 1.13, 1.16, and 1.41 times higher than those of binary RGO/g-C 3 N 4, g-C 3 N 4 /BiVO 4, and RGO/BiVO 4, respectively. The enhanced photocatalytic performance can be ascribed to the synergistic effect between the Z-scheme charge-carrier separation and RGO electron mediator, where RGO serves as a promoter for accelerating charge separation at the heterojunction, thus further leading to the improved photocatalytic activity. It is anticipated that the construction of RGO/g-C 3 N 4 /BiVO 4 Z-scheme heterostructures is an effective strategy for the development of high-performance photocatalysts for the degradation of tetracycline hydrochloride.

Photocatalysis has attracted great attention due to its useful environmental applications for hazardous pollutants degradation and sustainable hydrogen evolution. Recently, transition metal dichalcogenide (TMD) based materials have shown great potential in photocatalysis field. Due to their special two-dimensional layered structure and excellent electrochemical catalysis properties, they can be used as effective cocatalysts and supports to modify semiconductors for enhanced photocatalytic activities. By loading TMDs as cocatalysts, stable junctions could be created to facilitate the photogenerated electrons transfer. Moreover, the exposed edges of TMDs are active for hydrogen evolution or oxygen activation, thus leading to the improved performance for semiconductor/TMD composite in photocatalytic H 2 evolution and pollutants degradation. This review will focus on the roles of TMDs as cocatalysts for semiconductors in photocatalytic hydrogen evolution and environmental remediation. We expect our work can provide enriched information to harvest the excellent special properties of TMDs…

In this work, flowerlike nickel 2-methylimidazole metal–organic framework (Ni-MOF) was prepared by a solvothermal method. Vertically aligned Ni-MOF was fabricated from graphene oxide (GO) solution in the same way. The combination of GO and Ni-MOF (GOF) obviously suppressed the agglomeration of Ni-MOF sheets. As-synthesized, GOF has bigger pore volume and specific surface area, which are beneficial for volatile degradation products adsorption. It is noteworthy that the addition of GOF obviously reduced the fire hazard of polystyrene (PS). More than 33% decrease in the peak heat release rate for the PS/GOF composite was obtained when the content of the additives is only 1.0 wt %. Meanwhile, the reductions of total smoke and CO production were also prominent during the combustion of PS/GOF, respectively 21% and 52.3% decreases compared with that of pure PS. The synergism effects between layered GO and porous Ni-MOF realized the improved performances of PS. Thus, this work paves a feasible pathway to design efficient flame retardants for enhancing fire safety of polymers.

Supported metal single atoms have demonstrated excellent catalytic performance for many chemical transformations. The effects of support on the catalytic performance of supported single metal atoms, however, have not been clearly elucidated. We carried out a systematic investigation of the effects of supports on CO oxidation by single Pt (Pt 1 ) atoms dispersed on different metal oxides: highly reducible Fe 2 O 3, reducible ZnO, and irreducible γ-Al 2 O 3 . It was found that Pt 1 atoms on three metal oxides are active for CO oxidation, and the chemical properties of supports determine the catalytic performance of Pt 1 single-atom catalysts (SACs). Both the presence of −OH groups on support surfaces and the addition of H 2 O significantly modify CO oxidation on three SACs and reduce the effects of supports on their catalytic performances. We conclude that the interaction between single metal atoms and support as well as surface properties of supports control the catalytic behavior of SACs.

In this work, two hydrostable Cr-based metal–organic frameworks (MOFs), MIL-101(Cr) and MIL-101(Cr)-SO 3 H, were successfully synthesized and applied in the adsorption and separation of ionic dye fluorescein sodium (FS) and cationic dye safranine T (ST). Interestingly, MIL-101(Cr) can efficiently adsorb FS dye but hardly adsorbs ST dye, and MIL-101(Cr)-SO 3 H exhibits the thoroughly opposite phenomenon. More importantly, the reversed adsorption with high selectivity on the two MOFs can also be attained in the mixed solutions of the dyes. Finally, a mechanism analysis indicates that this significant reversal in performance for the dyes is mainly attributed to the opposite surface charges of the two MOFs caused by −SO 3 H groups.

Tetrahydrofurfuryl alcohol (THFAL), as a green industrial solvent, can be obtained directly from biomass-derived furfural with 100% conversion and 100% yield over a hydroxyapatite-supported Pd catalyst (Pd-HAP) under relatively mild conditions (40 °C, 1 MPa H 2, and 3 h) in 2-propanol. At room temperature and reacting for 8 h, the yield of THFAL was more than 99%. By capturing the intermediates, two pathways were proposed as follows: (1) Furfural was partially hydrogenated to furfuryl alcohol, and then, furfuryl alcohol was further hydrogenated to THFAL. (2) Furfural and 2-propanol first formed 2-(isopropoxymethyl)furan (2-IPMF) via etherification, and then, 2-IPMF was ultimately converted to THFAL. The Pd-HAP catalyst was characterized by various techniques including XRD, SEM, TEM, HAADF-STEM, XPS, and ICP-AAS. The results revealed that the outstanding catalytic performance of Pd-HAP was attributed to the quasicoordination effect between Pd and HAP, which not only contributed to highly dispersed and stable Pd nanoclusters but also led to better activation of hydrogen. The…

An in situ IR study unraveled that adsorption of CO 2 on 20 μm TEPA film at 50 °C followed a zwitterion-intermediate pathway: zwitterion → ammonium carbamate. H 2 O in the mixed TEPA/H 2 O (5:1) film decreased the rate of CO 2 adsorption but increased the amine efficiency. CO 2 preferentially adsorbs on primary amine sites and H 2 O on secondary amine sites. The presence of H 2 O promotes the formation of carbamic acid and produces a broad IR band centered at 2535 cm –1, which can be assigned to the ν(O–H) of hydronium carbamate, −NCOO – ···H–OH 2 + . The broadness of this 2535 cm –1 band ranging from 2100 to 2800 cm –1 persists at 120 °C. These broad components of the band can be ascribed to ν(N–H) in hydrogen-bonded ammonium carbamate, a R–NH 3 + /R 1 R 2 –NH 2 + ···–NCOO – moiety. The binding strength of adsorbed species on the TEPA film increases in the order adsorbed H 2 O < carbamic acid < ammonium carbamate < hydrogen-bonded water/ammonium carbamate.

Reverse osmosis and nanofiltration are highly adopted, growing technologies that are used to remove salts and other small molecules in water treatment. Both of these technologies primarily use cross-linked polyamide membranes to achieve the desired separation. Many novel nanoporous materials are being developed as alternatives or complements to polyamides, including graphene, graphene oxide, block copolymers, liquid crystals, aquaporins, and other biologically inspired molecular channels. This article evaluates each of these technologies by (i) reviewing the current progress in each area, (ii) identifying key needs for immediate research, and (iii) evaluating considerations for commercial development. The economic benefits of these technologies in reverse osmosis applications are further reviewed to help frame the expected commercial value proposition.

With advances in porous carbon synthesis techniques, hierarchically porous carbon (HPC) materials are being utilized as relatively new sorbents for CO 2 capture applications. These HPC materials were used as a platform to prepare samples with differing textural properties and morphologies to elucidate structure–property relationships. It was found that high microporous content, rather than overall surface area, was of primary importance for predicting good CO 2 capture performance. Two HPC materials were analyzed, each with near identical high surface area (∼2700 m 2 /g) and colossally high pore volume (∼10 cm 3 /g), but with different microporous content and pore size distributions, which led to dramatically different CO 2 capture performance. Overall, large pore volumes obtained from distinct mesopores were found to significantly impact adsorption performance. From these results, an optimized HPC material was synthesized that achieved a high CO 2 capacity of ∼3.7 mmol/g at 25 °C and 1 bar.

The development of metal-free catalysts for hydrogenation reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) has been of great increasing scientific and industrial importance. Herein, we reported the preparation of sulfurized graphene (SG) nanomaterials by a well-developed ball-milling method. The as-prepared SG nanomaterials were systematically characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared, and X-ray photoelectron spectroscopy. The SG exhibited flake-like morphology with average size of 100 nm, and the S doping (3.4 atom %) into the nanocarbon molecules results in asymmetry of electron density distribution, providing high catalytic performance for catalytic reduction of 4-NP to 4-AP by using NaBH 4 as the reducer. The related catalytic mechanism and reaction path of the reduction were investigated. The effects of different initial 4-NP concentrations, initial reductant concentrations, catalyst dosages, and reaction temperatures were presented, which have not been reported so far. The thermodynamic parameters…

A Helmholtz energy functional based on the Perturbed-Chain Polar Statistical Associating Fluid Theory Equation of State is proposed. A weighted density approximation is used to develop two variants of dispersion functionals. We conduct molecular simulations (Monte Carlo) in order to assess both models. The structure of thin liquid adsorbed layers of a few molecular diameters thickness are shown to be particularly meaningful to detect deficiencies of Helmholtz energy functionals and thus discriminate between models. We further compare the model to experimental data of interfacial tensions for pure components and for binary mixtures exhibiting vapor–liquid equilibria and liquid–liquid equilibria. The proposed Helmholtz energy functional is in good agreement with experimental data of pure (organic) substances and mixtures and compares well with molecular simulation data of fluids adsorbing at solid interfaces.

In this work, H 2 O 2 is electrogenerated in the cathodic compartment of a divided filter-press cell with a carbon cloth in the configuration of a gas diffusion electrode using air as the oxygen source. The effect of Teflon content was studied, and it was found that the appropriate content is within the range 10–20%. The production was greatly enhanced after the air-brushing deposition (and subsequent annealing) of simply 0.5 mg cm –2 of carbon black. Higher additions clogged the pores and as a result were counterproductive in terms of H 2 O 2 generation. At a current density of 25 mA cm –2, the production rate was 15 mg of H 2 O 2 h –1 cm –2 with a current efficiency close to 100%. Production rate increased with current density up to more than 40 mg of H 2 O 2 h –1 cm –2 at 87.5 mA cm –2 . The good performance and ease of preparation of this electrode make it an interesting alternative to generate hydrogen peroxide for electro-Fenton processes.

This manuscript demonstrates the synthesis of selective Lewis-acid sites in a metal–organic framework (MOF) for glucose transformation to 5-hydroxymethylfurfural (HMF). These sites are synthesized via partial phosphate modification of zirconia-cluster nodes in MOF NU-1000, which titrates strong Lewis-acid sites that would lead to undesired side reactions. Our mechanistic study using isotope tracer analysis and kinetic isotope effect measurements reveals that an isomerization–dehydration mechanism mainly occurs on the MOF catalyst, where fructose is an intermediate. This mechanism suggests that dilute concentrations are favorable in order to suppress undesired intermolecular condensation of glucose/fructose/HMF and maximize HMF yield. We demonstrate both high yield and selectivity of HMF formation of 64% with the MOF catalyst, at an initial glucose concentration of 1 mM in water/2-propanol. In stark contrast, similar partial phosphate modification of a bulk zirconia yields a catalyst that exhibits poor HMF selectivity, while possessing nearly identical Brønsted acidity to the…

We demonstrated a proof-of-concept catalytic steam reforming flow reactor system heated only by supported magnetic nickel–cobalt nanoparticles in an oscillating magnetic field. The heat transfer was facilitated by the hysteresis heating in the nickel–cobalt nanoparticles alone. This produced a sufficient power input to equilibrate the reaction at above 780 °C with more than 98% conversion of methane. The high conversion of methane indicated that Co-rich nanoparticles with a high Curie temperature provide sufficient heat to enable the endothermic reaction, with the catalytic activity facilitated by the Ni content in the nanoparticles. The magnetic hysteresis losses obtained from temperature-dependent hysteresis measurements were found to correlate well with the heat generation in the system. The direct heating of the catalytic system provides a fast heat transfer and thereby overcomes the heat-transfer limitation of the industrial-scale steam reformer. This could consequently enable a more compact steam reformer design.

Fragrant and antimicrobial properties were conferred to cotton fabrics following microencapsulation using green materials. Limonene and vanillin microcapsules were produced by complex coacervation using chitosan/gum Arabic as shell materials and tannic acid as hardening agent. The effect of two emulsifiers; Span 85 and polyglycerol polyricinoleate (PGPR), on the encapsulation efficiency (EE%), microcapsule’s size and morphology, and cumulative release profiles was studied. The mean diameter of the produced microcapsules ranged between 10.4 and 39.0 μm, whereas EE% was found to be between 90.4% and 100%. The use of Span 85 resulted in mononuclear morphology while PGPR gave rise to polynuclear structures, regardless of the core material (vanillin or limonene). The obtained microcapsules demonstrated a sustained release pattern; namely the total cumulative release of the active agents after 7 days at 37 ± 1 °C was 75%, 52% and 19.4% for the polynuclear limonene microcapsules, the mononuclear limonene microcapsules and the polynuclear vanillin microcapsules, respectively. Grafting of…

Microstructured calcium alginate (Ca-Alg) hydrogel exhibiting superhydrophilicity and underwater superoleophobicity is prepared for high speed and highly efficient oil/water separation. The fabricated mesh works in highly acidic or basic, salty, and high-temperature environments because of the stability of Ca-Alg. Moreover, nonwoven fabric used as a template for Ca-Alg is capable of separation of an oil-in-water emulsion.

Four azole-based DESs from acetyl choline chloride (ACC) and azoles (imidazole, Im, and 1,2,4-triazole, Tri) were prepared and utilized for SO 2 capture. Their physicochemical properties, including density, viscosity, TGA, freezing point, and pH, were determined. The influences of temperature and pressure on the SO 2 absorption performance of the DESs were systematically conducted. The results showed that all the DESs exhibited efficient and reversible absorption for SO 2, and ACC-Im possessed higher absorption capacity than ACC-Tri, with the maximum value of 0.381 g of SO 2 per g of ACC-Im (1:2) DES at 303.15 K and 0.1 bar. The possible absorption mechanism was investigated using 1 H NMR and FTIR spectroscopy. Furthermore, the ACC-Tri (1:2) was used to capture SO 2 at low partial pressure, showing high available capacity of 0.116 g of SO 2 per g of DES for 3300 ppm of SO 2 . Present DESs emerge as promising absorbents for SO 2 due to easy preparation, high absorption capacity, and good reversibility.

Nanofluid of graphene-based amphiphilic Janus nanosheets produced high-efficiency tertiary oil recovery at a very low concentration (0.01 wt %). The more attractive way is to use nanofluid during the secondary oil recovery stage, which can eliminate the tertiary stage and save huge amounts of water, especially at times when the price of oil is low. Here, we continue to report our findings on the application of the same nanosheets in secondary oil recovery, which increased oil recovery efficiency by ≤7.5% at an ultralow concentration (0.005 wt %). Compared with nanofluids of homogeneous nanoparticles, our nanofluid achieved a higher efficiency at a much lower concentration. The nanosize dimension of this two-dimensional carbon material improves transport in rock pores. After single-side surface hydrophobization of oxidized graphene with alkylamine, the partial restoration of the graphitic sp 2 network was detected by Raman, ultraviolet–visible, etc. The amphiphilic Janus nature of nanosheets led to their unique behavior at toluene–brine interface. Oil immersion testing clearly showed…

CO 2 decomposition to CO and O 2 was investigated in a dielectric-barrier discharge (DBD) reactor packed with BaTiO 3 balls, glass beads with different sizes, and a mixture of a Ni/SiO 2 catalyst and BaTiO 3 balls at lower temperatures and ambient pressure. The property of packing beads and the reactor configuration affected the reaction significantly. The Ni/SiO 2 catalyst samples were characterized by SEM, XRD, BET, and TEM. The combination of a DBD plasma and a Ni/SiO 2 catalyst can enhance CO 2 decomposition apparently, and a reaction mechanism of the plasma assisted CO 2 dissociation over the catalyst was proposed. In comparison with the result packed with glass balls (3 mm), the combination of BaTiO 3 beads (3 mm) with a stainless steel mesh significantly enhanced the CO 2 conversion and energy efficiency by a factor of 14.8, and that with a Ni/SiO 2 catalyst by a factor of 11.5 in a DBD plasma at a specific input energy (SIE) of 55.2 kJ/L and low temperatures (<115 °C).

A series of novel dual-emitting solid solution phosphors, (Ca,Sr) 10 Li(PO 4 ) 7:Ce 3+, Mn 2+ (CSLP:Ce 3+,Mn 2+ ), were synthesized by high-temperature solid-state method. CSLP:Ce 3+,Mn 2+ exhibits both Ce 3+ violet emission and Mn 2+ red emission under UV excitation. It is found that Sr 2+ partial substitution of Ca 2+ could result in enhancement of Mn 2+ emission intensity and blue-shift of Mn 2+ emission wavelength, which is due to site symmetry reduction and polyhedron expansion, respectively. The Ce 3+ –Mn 2+ energy transfer (ET) is efficient (∼90%), and the ET mechanism is dipole–dipole interaction. The application potential of CSLP:Ce 3+,Mn 2+ in optical thermometry was studied by exploiting the temperature sensitivity of the fluorescent intensity ratio (violet/red). It is found that the intensity ratio of the Ce 3+ and Mn 2+ emission peak linearly related to the temperature from 293 to 473 K with sensitivity of 0.40% K –1 . These results reveal that CSLP:Ce 3+,Mn 2+ may be a potential candidate for a luminescent ratiometric thermometer with wide temperature range.

Mechanochemical synthesis, driven the chemical transformation by mechanical force, has been a rapid and efficient strategy to prepare metal–organic frameworks (MOFs). In this work, a liquid-assisted mechanochemical method has been successfully applied to the synthesis of copper based MOF-505. The crystallinity and porosity of MOF-505 were investigated by adjusting the synthesis parameters, such as added solvent (type and amount) and grinding time. Results showed that the type and amount of added solvent were crucial parameters for the mechanochemical synthesis of MOF-505. Furthermore, the optimizations of MOF-505 synthesis were carried out: grinding Cu(OAc) 2 ·H 2 O and H 4 bptc as starting materials for 80 min with 0.4 mL of DMF assisted, giving MOF-505-K with Brunauer–Emmett–Teller (BET) surface area of 977 m 2 /g. Meanwhile, MOF-505-K had moderate CO 2 adsorption capacity of 2.01 mmol/g at 298 K and 100 kPa. The adsorptive selectivity determined from ideal adsorbed solution theory (IAST) indicated that MOF-505-K had high CO 2 /N 2 and CO 2 /CH 4 selectivities (26.6 and 5.5) at…

In this work, lignin/zinc oxide nanocomposites with excellent UV-absorbent performance were prepared through a novel hydrothermal method using industrial alkali lignin (AL) as raw materials. AL was first modified by quaternization to synthesize quaternized alkali lignin (QAL). The QAL/ZnO nanocomposites with different lignin contents were then prepared via a facile one-step hydrothermal method using QAL and zinc nitrate hexahydrate and hexamethylenetetramine in aqueous solution. The prepared nanocomposite possessed an average diameter of ∼100 nm and showed excellent synergistic UV-absorbent performance. The particle morphology and hybrid structure were carefully characterized by SEM, TEM, XRD, FT-IR, XPS, UV–vis, and TG analyses. Interestingly, it was found that the UV transmittance of polyurethane (PU) film was significantly reduced and the mechanical properties of the PU were significantly enhanced when blended with the prepared QAL/ZnO nanocomposite. The results of this work were of practical importance for high value-added application of industrial lignin in the field of…