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In recent years, Co, N co-doped carbon (Co–N–C) materials as oxygen reduction reaction (ORR) catalysts have attracted great attention because of their good ORR stability as well as decent activity. Co-doped zeolitic imidazolate framework-8 (Co@ZIF-8) as the precursor for synthesizing Co–N–C has attracted great interest recently. Co@ZIF-8 synthesis method may affect the properties of the as-synthesized Co@ZIF-8 precursors, which will surely affect the properties and ORR performance of Co@ZIF-8-derived Co–N–C catalysts. Herein, three methods, viz. room-temperature stirring method, reflux method, and hydrothermal method, were used to synthesize Co@ZIF-8 precursors. Physical characterization shows that the synthesis method has a great influence on the textural properties, composition, and graphitization degree of the as-synthesized Co–N–C catalysts. Electrochemical characterization shows that Co–N–C-R synthesized with reflux method exhibits an onset potential (Eonset) of 0.905 V, a half-wave potential (E1/2) of 0.792 V and a limiting current density (JL) of 5.85 mA cm−2 in acidic media, which are higher than those of Co–N–C–S (Eonset = 0.870 V, E1/2 = 0.770 V, JL = 4.71 mA cm−2) and Co–N–C–H (Eonset = 0.892 V, E1/2 = 0.785 V, JL = 4.68 mA cm−2) synthesized with room-temperature stirring method and hydrothermal method, respectively. The better ORR activity observed on Co–N–C-R can be attributed to its larger graphitization degree and larger mesopore volume. Catalytic stability test shows that Co–N–C-R has negligible activity loss after 5000 potential cycles. This work demonstrates that reflux method is a more suitable method for synthesizing Co–N–C catalysts for ORR.

Porous liquids, a new porous material with fluidity, can be applied in numerous fields, such as gas storage and/or separation. In this work, the separation of binary gas mixtures CO2/N2 and CO2/CH4 with porous liquids was examined by molecular dynamics (MD) simulations. The pure gas adsorption capacity was analyzed with different concentrations of porous liquids. The dependence of the separation effect of a gas mixture on the total pressure and temperature was investigated. Meanwhile, for both CO2/N2 and CO2/CH4 systems, the adsorption and separation effects of porous liquids with a cage:solvent ratio of 1:12 are better than those of 1:91 and 1:170. The results of the spatial distribution function and/or trajectories indicated that porous liquids prefer CO2, leading to the location of CO2 in the channels formed in porous liquids. However, N2 and CH4 are hardly adsorbed into the bulk. The diffusion of gas molecules follows the order of CO2 > N2 (for CO2/N2) and CH4 > CO2 (for CO2/CH4) in the bulk and N2 > CO2 (for CO2/N2) and CH4 > CO2 (for CO2/CH4) at the interface of porous liquids. Upon increasing the concentrations of porous liquids, the working capacities of CO2 show small decreases in CO2/N2 and CO2/CH4 systems, but the sorbent selection parameters are higher in pressure- and temperature-swing adsorption processes. The porous liquid with a cage:solvent ratio of 1:12 is more suitable for the separation of CO2/N2 and CO2/CH4 systems than ratios of 1:91 and 1:170.

Fe/N/C full of ultrafine Fe-based species and pores is synthesized by pyrolyzing a g-C3N4-coordinated Fe matrix embedded in carbon for oxygen reduction. Enhanced oxygen reduction activity is observed on Fe/N/C with higher pore volume and the Fe/N/C catalyst with the largest pore volume shows the highest half-wave potential of 0.890 V.

Herein, by screening 89 porous materials (metal–organic frameworks and covalent organic frameworks), the ultradeep desulfurization from model gasolines was investigated by the facile adsorptive app...

The scarcity and poor long-term stability of Pt has greatly hindered its commercial application as oxygen reduction reaction (ORR) catalyst. In this work, carbon-supported Pd9Au1 alloy particles with a Pd/Au molar ratio of 9:1 synthesized by using an ethylene glycol-based reduction method were used to catalyze ethanol oxidation to coat Pd9Au1 core with Pt atomic layers to synthesize Pd9Au1@Pt/C catalyst. Physical characterization shows that the as-synthesized Pd9Au1@Pt/C catalysts present a well-defined core-shell structure and the surface Pt layers can be well controlled by tuning the amount of Pt precursor added during synthesis. Electrochemical characterization shows that among the synthesized catalysts Pd9Au1@Pt2/C with 2 atomic Pt layers exhibits the best activity and excellent stability for ORR, as evidenced by its even increased half-wave potential after 10000 potential cycles between 0.6 and 1 V in O2-saturated 0.1 M HClO4 solution. This enhanced ORR activity and stability of Pd9Au1@Pt2/C catalyst can be attributed to the compressive strain and stabilizing effect of Pd9Au1 core on Pt shell.

NH3 decomposition over non-noble catalyst to generate COx-free H2 has attracted great attention in recent years. In this work, fumed SiO2-supported Ni, Co and Ni–Co bimetallic catalysts are synthesized by using a co-impregnation method and evaluated for NH3 decomposition, which shows that the bimetallic catalysts exhibit better catalytic activity than the monometallic ones. This enhanced activity observed on bimetallic catalyst can be largely attributed to the more appropriate catalyst metal-N binding energy resulting from the synergistic effect between Ni and Co in the formed Ni–Co alloy. Among the synthesized catalysts, Ni5Co5/SiO2 synthesized with the Ni/Co molar ratio of 5:5 achieves 76.8% NH3 conversion under a GHSV of 30,000 mL h−1 g−1cat at 550 °C and shows the best catalytic activity, which can be further improved by doping with K (78.1% NH3 conversion at 30,000 mL h−1 g−1cat), and the obtained Ni5Co5/SiO2–K also shows excellent catalytic stability.

The commonly used Pt/C catalyst has low durability for oxygen reduction reaction (ORR). In this work, CNT-supported TiO2 nanoparticles, which synergistically combines the merits of TiO2 (high stability and strong interactions with the supported Pt nanoparticles) and CNT (high specific surface area and large electrical conductivity), are prepared by a sol-gel process coupled with an annealing process and used as the support for Pt nanoparticles, which are anchored around TiO2 nanoparticles by a photodeposition technique. The as-synthesized Pt/TiO2@CNT catalyst exhibits a mass activity 5.3 times as large as that of the commercial Pt/C catalyst (0.358 A mgPt−1 vs. 0.067 A mgPt−1 at 0.9 V) and an excellent stability (no activity loss after 10000 potential cycles) for ORR, which can be mainly attributed to the lower oxygen adsorption energy of Pt, resulting from the strong metal-support interaction induced by the deposition of Pt nanoparticles around the well-dispersed TiO2 nanoparticles on CNT.

Among the Fischer-Tropsch synthesis (FTS) catalysts, Cobalt catalysts are currently attracting a lot of research interests due to their high activity and high selectivity. But the dispersion and reducibility of cobalt catalysts with moderate interaction between cobalt and support are still a challenge. A novel amino-ended hyperbranched polyamide (AEHPA) was used to modify SBA-15 and then was applied as support for obtaining cobalt catalyst (15Co/SBA-15-N). The catalysts were characterized by XRD, TEM, XPS and H2-TPR techniques. The results showed that AEHPA doped mesoporous SBA-15 caused the generation of N species in the SBA-15 pore channels. The N-Co bonds resulted in the formation of highly-dispersed cobalt nanoparticles with uniform sizes inside the ordered mesopores of support. AEHPA doping was an effective way to modify the surface properties of the SBA-15 for immobilizing cobalt nanoparticles. Compared with the conventional 15Co/SBA-15 catalyst without doping AEHPA, the AEHPA doped 15Co/SBA-15-N catalyst showed improved cobalt dispersion and stabilized cobalt location, which led to much better reaction stability as well as C5+ selectivity.

ZSM-5 seeds grafted mesoporous aluminosilicates with different morphologies (SZM-1 (two-dimensional (2D) structure), MZM-2 (three-dimensional (3D) structure), MZM-1 (mixture of 2D and 3D structure)) were synthesized by varying benzene addition amount. These composites were used as supports for Co (20 wt%) catalysts, which were prepared by simple incipient wetness impregnation method. Their catalytic performance was evaluated by Fischer–Tropsch synthesis (FTS) reaction. The supports and corresponding catalysts were characterized by N2 adsorption–desorption, XRD, TEM, H2-TPR, NH3-TPD techniques. 20Co/SZM-1 catalyst showed a highest FTS activity and best reaction stability, due to its higher cobalt dispersion, good cobalt reducibility and the confinement effect of two-dimensional structure. Compared to 20Co/SZM-1, 20Co/MZM-2 catalyst exhibited much higher selectivities to short-chain hydrocarbons and iso-paraffins, which may be attributed to the combination effects of its three-dimensional open pore structure and stronger acidity, leading to less diffusion limitation of hydrocarbon products and thus presenting a smaller chain-growth probability.

Nitrogen-doped carbon (N–C) materials are promising low-cost catalysts for oxygen reduction reaction (ORR). However, the commonly used route for N–C synthesis, viz., the high-temperature pyrolysis of N- and C-containing precursors, usually results in a great loss of N-containing species determining the ORR catalytic performance. Herein, porous N–C materials are synthesized by using g-C3N4 embedded in glucose-derived carbon as template and N source. The N–C sample synthesized at 900 °C with a mass ratio of glucose to g-C3N4 being 4:1 exhibits a positive half-wave potential (E1/2 = 0.823 V), good long-term stability and dominant 4 e− pathway for ORR in alkaline media, which can be attributed to its large specific surface area, high porosity, and large fraction of pyridinic and graphitic N. When a small amount of Fe is doped into the N–C sample, its ORR performance can be greatly improved and outperforms the commercial Pt/C catalyst in terms of ORR activity (E1/2 = 0.880 V), long-term stability and methanol tolerance. Notably, primary Zn-air batteries with N–C and Fe–N–C being the cathode catalysts exhibit peak power densities of 88 and 100 mW cm−2, respectively. This work offers a promising route for the synthesis of porous carbon-based materials highly efficient as ORR catalyst for Zn-air battery.

Comb-shaped polysulfone anion exchange membranes (AEMs) containing various pendant alkyl side chains were synthesized and characterized. Ionic clusters aggregation is observed in transmission electron microscopy (TEM) image and small-angle X-ray scattering (SAXS). The comb-shaped quaternized ammonium polysulfone (Cx-QAPSU) membranes show enhanced dimensional stability and ultra-low membrane area resistance (Rm). Notably, the C16-QAPSU with 16 carbon atoms has the best hydrophilic-hydrophobic phase separation structure and lowest Rm of 2.5 Ω cm2 despite low ion exchange capacity (IEC) of 1.55 mmol/g and swelling ratio of 5.3%. Moreover, comb-shaped AEMs show much higher tensile strength (TS) compared to QAPSU membrane under the same IEC level. The C16-QAPSU with lowest Rm of 2.5 Ω cm2 exhibits the highest TS of 16.7 MPa. These results indicate that the long alkyl side chains especially the length of the pendant side chain of Cx-QAPSU up to C16 achieve an electrochemical-mechanical balance of AEMs. In electro-electrodialysis systems, the comb-shaped AEMs exhibit higher purification efficiency of wet phosphoric acid than non-comb-shaped AEMs.

Pyrolyzing precursors containing iron, nitrogen and carbon elements is a commonly used process for synthesizing Fe N C catalysts for oxygen reduction reaction (ORR). Generally, aggregation of iron-based species is prone to occur because of a lack of chemical bonds between iron-based species and carbon matrix and synthesizing highly porous Fe N C catalysts is difficult because carbon skeleton is prone to collapse during pyrolysis. Herein, highly porous Fe N C catalysts with fine iron-based species are synthesized by selecting glucose as carbon source, FeCl3 as iron source, and urea-derived g-C3N4 as nitrogen source, iron anchoring and stabilizing species, and pore-forming template. The multi-role g-C3N4-derived catalyst synthesized at 1100 °C (Fe N C 1100) has fine iron-based species, large specific surface area (737 m2 g−1), and extremely high pore volume (2.66 cm3 g−1). Accordingly, Fe N C 1100 shows a larger half-wave potential (E1/2 = 0.894 V), a higher stability (ΔE1/2 = 6 mV) after 10,000 potential cycles in alkaline media, and a higher peak power density (P = 152 mW cm−2) when employed as ORR catalyst of zinc-air battery, which are all superior to those of the commercial Pt/C catalyst (E1/2 = 0.864 V, ΔE1/2 = 30 mV, P = 134 mW cm−2). The present work brings a new method for synthesizing highly porous Fe N C catalysts decorated with fine active sites for ORR.

We employ molecular simulations to screen the best microporous materials for deep desulfurization of dry air. Pressure-swing adsorption and temperature-swing adsorption in desulfurization processes are investigated. The selectivity, working ability, selection parameters, and diffusivity of mixed gases are examined to evaluate those materials. The results show that UiO-66, ZIF-71, ZIF-69, and ZIF-97 exhibit good performance for the separation of H2S from air. The selectivity and adsorption capacity of H2S are larger than 300 and 0.01 mmol/g at room temperature and atmospheric pressure, respectively. UiO-66, ZIF-71, ZIF-69, MIL-100, Zn-DOBDC, ZnBDC, IRMOF-11, and MIL-140B are ideal materials to remove SO2 in air. The selectivity of SO2 is higher than 500 and the adsorption capacity is higher than 0.06 mmol/g. The diffusivity of sulfides is determined by the competition between the sterically hindered effect and the intermolecular synergistic effect. Comprehensive analysis found that zeolitic imidazolate frameworks (ZIFs) are good materials for the removal of sulfides.

The advantage of g-C3N4 as nitrogen-rich precursor for synthesizing nitrogen-doped carbon-based oxygen reduction reaction (ORR) catalyst has not been brought into full play. Herein, a simple approach with S-doped g-C3N4 (S-g-C3N4) and P123 as precursor for synthesizing nitrogen and sulfur co-doped carbon (N-S-C) catalysts highly efficient for ORR was developed. S-g-C3N4 synthesized via pyrolysis of a mixture of urea and thiourea was used as nitrogen and sulfur source, and P123 serving as carbon source was used to envelop S-g-C3N4 to form core–shell S-g-C3N4@P123 sample, whose pyrolysis yielded N-S-C catalyst. Characterization shows that the N-S-C catalyst synthesized at 900 °C with a S-g-C3N4/P123 mass ratio of 2:1 (N-S-C-2) exhibits the largest nitrogen and sulfur content and the highest half-wave potential of 0.863 V vs. RHE in alkaline media, which can be ascribed to the selection of the mixture of urea and thiourea for S-g-C3N4 synthesis, and the suitable S-g-C3N4/P123 mass ratio and pyrolysis temperature. N-S-C-2 also shows good ORR catalytic stability, excellent methanol tolerance, and high performance as the cathodic catalyst of Zn-air battery. This study gives full play to the advantage of g-C3N4 and provides a novel route for synthesizing N-S-C catalysts highly efficient for ORR.

A novel SBA-15 (2.5N-SBA-15) with pores penetrating into the silica walls has been synthesized with amino-ended hyperbranched polyamide (AEHPA) and P123 as co-templates. This novel template method successfully imprints mesoporous cavities into the silica structure. The obtained composites are used as a Co (15 wt%) catalyst support for Fischer–Tropsch Synthesis (FTS). The catalytic activity and product selectivity are significantly influenced by the support structure. Compared with the conventional 15Co/SBA-15 catalyst, the 15Co/2.5N-SBA-15 catalyst with a penetrating pore structure shows improved reducibility of cobalt species, leading to better catalytic properties with respect to CO activity and C5+ selectivity during the FTS reaction.

A ZIF-derived Fe–Zn–N–C catalyst with sufficient exposure of bimetallic active sites and well-balanced micro/mesopores is synthesized by a two-stage pyrolysis process and exhibits superior oxygen reduction activity with high half-wave potentials of up to 0.819 V in 0.1 M HClO4 and 0.918 V in 0.1 M KOH.

ZnO materials with a range of different morphologies have been synthesized via a simple solvothermal method in dimethylacetamide (DMAc) media. DMAc was used as the base source and solvent in such solvothermal syntheses for the first time. The effect of the DMAc content in the solvothermal process on nucleation, growth, and the final morphology of the ZnO nanostructures was investigated. XRD results revealed that single-phase ZnO with the wurtzite crystal structure was obtained for different DMAc contents in solution. X-ray photoelectron spectroscopy confirmed high purity of the as-prepared ZnO crystals. SEM imaging showed that ZnO with spherical shapes, dumbbell, and rod-like were synthesized by controlling DMAc content. In addition, vibrational properties of ZnO crystals with different morphologies were investigated by Raman spectroscopy. The optical properties of the as-prepared ZnO materials were investigated by UV–vis absorption and room temperature photoluminescence. The possible mechanism was also proposed to account for the growth of the ZnO crystals in the DMAc solvent.

ZnO crystals have been prepared via a simple aqueous solution route using zinc acetate-hexamethylenetetramine (HMTA) solution. To understand the role of HMTA in the formation processes of ZnO crystals, concentration measurements of Zn(II) remaining in the solution as well as SEM and XRD analyzes of the solid product have been made at regular intervals. The results demonstrated that the HMTA concentration has determinative effects on the growth rate of obtained ZnO products by controlling the composition of zinc complex species and mediating the transformation rate of building blocks. XRD results revealed the single phase nature with the wurtzite structure of the as prepared ZnO rods. X-ray photoelectron spectroscopy confirmed high purity of the ZnO rods. By varying the concentration of HMTA in the solution, the average size of rods was varied from 5 μm to 10 μm. Photoluminescence spectra indicated that the photoluminescent intensity of the emission peak at 380 nm increase to different degree with increasing HMTA concentration. These results revealed that the concentration of HMTA plays a vital role to control the properties of ZnO crystals.

Ion-exchange polymer SPEEK has been used as membrane material in proton exchange membranes and microfiltration/ultrafiltration /nanofiltration membranes. In the present study, SPEEK was synthesized by sulfonating of PEEK, afterward the SPEEKs were applied to prepare dense SPEEK/PES composite membranes for pervaporative desalination. Properties of the SPEEKs including thermal stability, ion exchange capacity and water uptake were measured. The SPEEK/PES membrane morphology and hydrophilicity were characterized. Influences of membrane prepare conditions (polymer concentration in supporting membrane, thickness of supporting membrane, sulfonation degree of SPEEK, coating layers and SPEEK concentration) and the pervaporation parameters (NaCl concentration and feed temperature) on the pervaporative desalination performance were studied. The SPEEK/PES composite membranes show high water flux up to 6 L/m2*h and salt rejection > 99.9%. During 40 h pervaporation for different NaCl concentrations (10–100 g/L) and temperatures (50–70 °C), the rejection maintains >99.9%. The permeate flux ranges to 2–6 L/m2 * h, depending on feed concentration and temperature. The total salt rejection of composite membranes is not affected by temperature and feed concentration, attributing to the supper hydrophilicity and stability of SPEEK. The results indicate that SPEEK could be considered as a candidate material for pervaporative desalination membrane.

SPEEK (sulfonated poly ether ether keton) is a type of very attractive polymeric material in membrane applications. Properties of SPEEK membranes can be tailored through controlling its sulfonation degree. However, the sulfonation degree affects the mechanical strength and membrane stability. SPEEK/PES composite membranes were prepared via a surface coating method. Those membranes show lower retentions due to the swelling of SPEEK. ZIF-8, constructed from zinc centers and 2-methlimidazole ligands, was incorporated into SPEEK to improve their performance. Sulfonation groups in SPEEK closely link to ZIF-8 through the coordination and electrostatic interactions, proved by ATR-IR characterizations and IEC measurements. The ionic crosslinked ZIF-8-SPEEK composite membranes show a higher desulfonation temperature and a lower swelling, evidenced by the TGA results and the water uptake values of ZIF-8-SPEEK composites. The crossflow filtrations show the ionic crosslinked ZIF-8-SPEEK composite membranes have good retentions of PEG1000 (70–90%), dyes (>90%) and salts (30–40%). The membrane retentions increase, whereas the permeances decrease after filling of ZIF-8. More than 100 h filtrations indicate that those membranes have a good stability. Although ZIF-8 particles are believed providing extra permeating channels, the strong ionic interactions have a domain effect on the membrane permeance.

The enhanced potassium leaching mechanism of phosphorus-potassium associated ore with sodium dodecyl sulfate (SDS) was systematically elucidated and attributed to the combined effects such as the wetting, adsorption, dispersion and permeation actions. First, the formation of the adsorption film with 1.25 g L−1SDS led to the surface tension and the contact angle obviously decreased, promoting the wetting, dispersion and permeation actions. Second, more acid and fluorine entered into the interior of the ore due to the enhanced molecular and convective diffusions and the enlarged fissures and particle size of the ore, leading to higher potassium dissolution fraction. However, much micelle covering on the residue fixed layer would be formed if 5.00 g L−1 SDS exceeded the critical micellization concentration (CMC), which hindered acid and fluorine entered into the interior, indicating decreased potassium dissolution fraction. Finally, an intensified leaching process schematic diagram of the ore in HCl-CaF2 media with SDS was developed. These novel findings demonstrate that SDS can enhance effectively and obviously the leaching of potassium from phosphorus-potassium associated ore. In addition, the intensified leaching mechanism by SDS will be helpful for efficient extraction, enrichment and utilization of mineral resources.

In this work, carbon-doped TiO2 nanocoating (TiO2–C) was prepared by a sol–gel process and employed as the support of Pt nanoparticles for methanol oxidation reaction (MOR). The obtained Pt/TiO2–C catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. XRD characterization shows that the average crystallite sizes of Pt particles and TiO2–C support are 2.7 and 6.5 nm, respectively. TEM characterizations show that Pt particles are highly dispersed on TiO2 nanocoating, which preserves its nanoscale structure without no apparent sintering after carbon doping. XPS characterization shows that the Pt particles anchored on TiO2–C exhibit positively shifted binding energies of Pt 4f. Cyclic voltammetry (CV) and chronoamperometry (CA) characterizations show that TiO2–C has a greatly enhanced electrical conductivity and Pt/TiO2–C catalyst has better electrocatalytic activity and stability than Pt/C catalyst for MOR, which could be attributed to the high dispersion of Pt particles on TiO2–C support, the strong metal-support interactions between Pt particles and TiO2–C support, and the rich active –OH species on TiO2–C support.

Carbon-doped TiO2 nanocoating (TiO2-C) on carbon black (CB) was prepared and employed as the support of Pd catalyst for ethanol oxidation reaction (EOR) in alkaline media. The obtained catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. TEM characterization shows that TiO2 nanocoating is formed uniformly on CB and still preserves its structure with no apparent sintering after carbon doping, and Pd particles are well dispersed on the conductive TiO2-C support. XRD characterization shows that TiO2-C presents an anatase structure. XPS characterization shows that oxygen vacancy defects resulting from carbon doping present in TiO2-C. Cyclic voltammetry (CV) and chronoamperometry (CA) results demonstrate that the as-prepared Pd/TiO2-C catalyst exhibits much enhanced catalytic activity and stability for EOR in alkaline media than Pd/C catalyst. The enhanced activity presented by the Pd/TiO2-C catalyst may result from the strong interactions between TiO2 and Pd, the facilitated oxidation removal of CH3COads intermediate, and the facilitated transportation of ethanol to Pd active sites.

Carbon nanotubes (CNTs) have attracted increasingly interest in preparing CNTs/epoxy nanocomposites for improving thermal and mechanical properties. The well distribution of prime CNTs in epoxy matrix is still a challenge due to the strong interaction among nanotubes and property of self-aggregation. Here, we report a highly efficient approach to functionalize prime CNTs by a thiol-ene click reaction between double bonds of CNTs and thiol groups of mercaptans, and the resulted in thiol-functionalized CNTs with different chemical chains show well dispersion in ethyl acetate and epoxy. The thiol-functionalized CNTs show a positive effect on reinforcing and toughening diglycidyl ether of bisphenol-A (DGEBA). With an increase in the thiol-functionalized CNTs content, the mechanical and thermal properties of the CNTs/DGEBA nanocomposites, including tensile, flexural and impact strengths, and thermal conductivity, increase first and then decrease. The maximum improvements on the tensile, flexural, impact strengths and thermal conductive were 43.75%, 25.11%, 196.44% and 33.81%, respectively. These grafted mercaptans chains play a bridging action between CNTs and epoxy matrix to supply a strong interaction, substantiated by their good rheological property and ductile SEM micrographs. Both the simple method of thiol-functionalized CNTs and preparation of CNTs/DGEBA nanocomposites will supply dependable data for wide application of CNTs.

To improve the oil conversion, high methanol/oil molar ratio is required in the continuous production of biodiesel via supercritical methanol transesterification in tubular reactor. And thus the subsequent excess methanol recovery needs high energy consumption. Based on the feature of high temperature and high pressure in supercritical methanol transesterification, excess methanol recovery in reaction system by flashing vaporation is conducted and the effect of reaction temperature, reaction pressure and flashing pressure on methanol recovery and methanol concentration in gas phase is discussed in detail in this article. Results show that at the reaction pressure of 9–15 MPa and the reaction temperature of 240–300 °C, flashing pressure has significant influence on methanol recovery and methanol content in gas phase, which can be effectively improved by reducing flashing pressure. At the same time, reaction temperature and reaction pressure also have an important effect on methanol recovery and methanol content in gas phase. At volume flow of biodiesel and methanol 1:2, tubular reactor pressure 15 MPa, tubular reactor temperature 300 °C and the flashing pressure 0.4 MPa, methanol recovery is more than 85% and methanol concentration of gas phase (mass fraction) is close to 99% after adiabatic braising; therefore, the condensate liquid of gas phase can be injected directly into methanol feedstock tank to be recycled. Research abstracts Biodiesel is an important alternative energy, and supercritical methanol transesterification is a new and green technology to prepare biodiesel with some obvious advantages. But it also exists some problems: high reaction temperature, high reaction pressure and large molar ratio of methanol/oil will cause large energy consumption which restricts supercritical methanol for the industrial application of biodiesel. So a set of tubular reactor-coupled flashing apparatus is established for continuous preparing biodiesel in supercritical condition and separation of excess methanol, which provides an appropriate method to solve the separation and recycle of excess methanol and waste heat utilization.

High methanol-to-oil ratio is required to obtain a high conversion of oil for the production of biodiesel with supercritical methanol. Recovering the methanol of a stream issuing from a transesterification supercritical reactor by flash distillation instead of evaporation was analyzed. The one-stage and two-stage flash distillation processes were presented and compared. The difference of the recovery percentage of methanol of the above two flash processes is less than 0.5% and the methanol concentration in the vapor for the one-stage process decreases rapidly when feed temperature increases. The process in which the product of transesterification of soybean oil with supercritical methanol is cooled to an appropriate temperature (about 240°C) first and then flashed was put forward. The effect of cooling temperature, feed pressure and flash pressure on methanol concentration and recovery percentage was investigated. According to this study, when the feed pressure range is 15–30 MPa, the flash pressure equals 0.4 MPa, and cooling temperature range is 240°C–250°C, the recovery percentage of methanol is not less than 85%, and the concentration of the vapor in mass fraction of methanol is approximately 99%. Thus, the vapor leaving the flash tank can be directly circulated to the transesterification reactor.

Biodiesel is an important renewable energy. Supercritical methanol transesterification for biodiesel has recently been concerned because of its obvious advantages. The tubular reactor is an ideal reactor for continuous preparation of biodiesel via supercritical methanol transesterification. A methanol preheating tube is necessary for the tubular reaction system because the reaction temperature for supercritical methanol transesterification is usually 520–600 K. Therefore, in the range of 298–600 K, changes of the density, isobaric capacity, viscosity and thermal conductivity of sub/supercritical methanol with temperature are first discussed. Then on the basis of these thermophysical properties, an integration method is adopted for the design of sub/supercritical methanol preheating tube when methanol is preheated from 298 K to 600 K at 16 MPa and the influencing factors on the length of the preheating tube are also studied. The computational results show that the Reynolds number Re and the local convection heat-transfer coefficient α of sub/supercritical methanol flowing in Φ6× 1.5 mm preheating tube change drastically with temperature. For the local overall heat transfer coefficient K and the average overall heat transfer coefficient Km, temperature also has an important influence on them when the inlet velocity of methanol is lower than 0.5 m/s. But when the inlet velocity of methanol is higher than 0.5 m/s, K and Km almost keep invariable with temperature. Additionally, both the outlet temperature and the inlet velocity of methanol are the key affecting factors for the length of the preheating tube, especially when the outlet temperature is over the critical temperature of methanol. At the same time, the increase of tin bath’s temperature can shorten the required length of the preheating tube. At the inlet flow rate of 0.5 m/s, the required length of the preheating tube is 2.0m when methanol is preheated from 298 K to 590 K at 16 MPa with keeping the tin bath’s temperature 620 K, which is in good agreement with the experimental results.

Dissolution of cellulose with ionic liquids allows the comprehensive utilization of cellulose by combining two major green chemistry principles: using environmentally preferable solvents and bio-renewable feed-stocks. In this paper, the dissolution of cellulose with ionic liquids and its application were reviewed. Cellulose can be dissolved, without derivation, in some hydrophilic ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-allyl-3-methylimidazolium chloride (AMIMCl). Microwave heating significantly accelerates the dissolution process. Cellulose can be easily regenerated from its ionic liquid solutions by addition of water, ethanol or acetone. After its regeneration, the ionic liquids can be recovered and reused. Fractionation of lignocellulosic materials and preparation of cellulose derivatives and composites are two of its typical applications. Although some basic studies, such as economical syntheses of ionic liquids and studies of ionic liquid toxicology, are still much needed, commercialization of these processes has made great progress in recent years.