A mathematical model considering the effects of axial mixing of continuous phase and polydispersity of dispersed emulsion drops was developed to describe the mass transfer mechanism of an emulsion liquid membrane (ELM) in a modified rotating disc contactor (MRDC). The calculated results indicate that the axial mixing lowered the concentration gradient along the column, and the polydispersity caused the maldistribution of the interfacial area and the volume for the different sized drops, which also reduced the mass transfer performance. In order to evaluate the degree of the axial mixing and the polydispersity, the important variables affecting axial dispersion coefficient (EM), emulsion phase holdup (Φ), and drop size distribution (α and β) including rotating speed, flow ratio, total flow, surfactant concentration, and stirring paddle width were also studied. It was found that the standard deviation of the drop size (β) had same variation trend as the mean drop size (α). The increase in the rotating speed and the paddle width enhanced the turbulence which increased the EM and the Φ and simultaneously decreased the α and the β. The increase in the flow ratio markedly increased the Φ, the α, and the β, whereas the increase in the total flow signally increased the EM. The increase in the surfactant concentration primarily decreased the α and the β; meanwhile, the membrane leakage was obviously inhibited. Finally, the dimensionless correlations were established to predict these hydrodynamic parameters (EM, Φ, α, and β) with the AAREs of 5.2%, 7.5%, 2.7%, and 4.4%, respectively.

Associated with the carbonization of glucose in the hydrothermal process, MoS2/amorphous carbon composites were synthesized by a one-step hydrothermal method and characterized by various technologies. Introducing carbon into MoS2 increased its surface area and enlarged the edge-to-corner ratio of the MoS2 slab of the MoS2 phase, which contributed to a high deoxygenation degree in the hydrodeoxygenation (HDO) of p-cresol, but excessive carbon covered some MoS2 edges that acted as active sites for HDO reaction and lowered the conversion. The presence of water modified the surface structure of MoS2 and had a great effect on the HDO activity and product distribution. During the HDO reaction, sulfur–oxygen exchange at the edges of MoS2 resulted in the loss of S atoms and the intensity decrease of the (002) diffraction peak for MoS2 phase, which was accelerated by increasing the amount of added water. Carbon in MoS2 only acted as a support and had no preventing effect on water. When the added water was 0.2 g, i.e., water/p-cresol molar ratio was 0.5:1, after reaction at 275 °C for 8 h, toluene selectivity and deoxygenation degree increased to 91.3% and 94.2%, respectively.

Because of energy crisis, how to minimize hydrogen consumption and improve the catalytic activity is of importance for the hydrodeoxygenation (HDO) of phenols. In this study, Co–Mo–S catalysts were prepared by a one-step hydrothermal method, and their properties were characterized by nitrogen physisorption, X-ray diffraction, and transmission electron microscopy. The effects of Co content and catalyst preparation temperature on the catalytic activity were studied using the HDO of p-cresol as a probe. The effects of reaction conditions such as temperature and hydrogen pressure on the conversion and product distribution were also studied. Adding Co into the MoS2 catalyst decreased its surface area but increased the HDO activity and reduced the hydrogen consumption. The HDO of p-cresol on Co–Mo–S proceeded with two separate reaction routes: hydrogenation–dehydration (HYD) and direct deoxygenation (DDO). The HDO active sites were well explained by the Rim–Edge model. The high conversion of p-cresol and low HYD/DDO was attributed to the short slab length and high number of layers in stacks, respectively.

Hydrophobic reduced graphene oxide supported Ni-B-P-O and Co-B-P-O catalysts were synthesized by a chemical reduction method and these dispersed relatively well in a non-polar solvent, prevented contact with water, and consequently protected the active phases and exhibited high catalytic activity in the liquid-phase p-cresol hydrodeoxygenation reaction: both the conversion and deoxygenation degree were higher than 99% at 225 °C for 1 h.

CoS2/MoS2 catalysts were prepared using a two-step hydrothermal procedure for the first time, i.e., MoS2 was synthesized and then CoS2 was prepared and deposited on the surface of the MoS2. The characterization results presented that CoS2 and MoS2 are separated in the resultant catalysts and the surface area of CoS2/MoS2 was much higher than that of Co–Mo–S prepared using a one step method. In the hydrodeoxygenation (HDO) of p-cresol, the presence of CoS2 enhanced the conversion, but excessive CoS2 on the surface of the MoS2 reduced its activity. With an appropriate amount of CoS2, the catalyst presented an unprecedented HDO activity and direct deoxygenation (DDO) selectivity: 98% deoxygenation degree with a selectivity of 99% toluene at 250 °C for 1 h. This CoS2/MoS2 catalyst also exhibited high DDO activity for other phenolic monomers, which minimized hydrogen consumption and improved the economic efficiency.

ZrO2–Al2O3 and CeO2–Al2O3 were prepared by a co-precipitation method and selected as supports for Pt catalysts. The effects of CeO2 and ZrO2 on the surface area and Brønsted acidity of Pt/Al2O3 were studied. In the hydrodeoxygenation (HDO) of p-cresol, the addition of ZrO2 promoted the direct deoxygenation activity on Pt/ZrO2–Al2O3 via Caromatic–O bond scission without benzene ring saturation. Pt/CeO2–Al2O3 exhibited higher deoxygenation extent than Pt/Al2O3 due to the fact that Brønsted acid sites on the catalyst surface favored the adsorption of p-cresol. With the advantages of CeO2 and ZrO2 taken into consideration, CeO2–ZrO2–Al2O3 was prepared, leading to the highest HDO activity of Pt/CeO2–ZrO2–Al2O3. The deoxygenation extent for Pt/CeO2–ZrO2–Al2O3 was 48.4% and 14.5% higher than that for Pt/ZrO2–Al2O3 and Pt/CeO2–Al2O3, respectively.

•Flower-like Co–Mo–S catalyst was synthesized by a facile hydrothermal synthesis.•Co–Mo–S exhibited a high activity and aromatics selectivity in p-cresol HDO and benzothiophene HDS.•The synergy between CoS2 and MoS2 and flower-like morphology resulted in the high HDO activity.•Adding appropriate benzothiophene into the HDO of p-cresol on Co–Mo–S maximized the deoxygenation degree.•Adding p-cresol decreased the desulfidation activity in benzothiophene HDS because of the competitive adsorption.Co–Mo–S catalysts were synthesized by a facile hydrothermal synthesis and their activities were tested in the hydrodeoxygenation (HDO) of p-cresol, hydrodesulfurization (HDS) of benzothiophene, and simultaneous HDO of p-cresol and HDS of benzothiophene. When Co/Mo mole ratio in Co–Mo–S was adjusted to 0.3, the catalyst presented a flower-like morphology and exhibited high HDO and HDS activity, which was attributed to its specific structure and the maximum synergy between CoS2 and MoS2. In the HDO of p-cresol, direct deoxygenation (DDO) was the main reaction route and toluene selectivity reached to 97.5%. The hydrogen consumption was markedly cut down. By adding small amount of benzothiophene, p-cresol conversion was enhanced because the produced H2S from the HDS of benzothiophene slowed down the catalyst deactivation. In simultaneous HDO of p-cresol and HDS of benzothiophene, because of the competitive adsorption of reactants on the active sites, both the toluene selectivity and desulfurization degree were lowered compared with the single component reactions.Flower-like Co–Mo–S catalyst was synthesized by a facile hydrothermal synthesis and exhibited high activity and aromatics selectivity in the HDO of p-cresol and HDS of benzothiophenes. Adding appropriate amount of benzothiophene into the HDO of p-cresol over Co–Mo–S enhanced the deoxygenation degree. In the simultaneous HDO and HDS reactions, the initial reaction rate constant for p-cresol/benzothiophene, DDO activity or desulfidation degree were decreased compared with that in single reactions.

•Two-step hydrothermal method was developed for the synthesis of NiS2//MoS2 catalysts.•NiS2 and MoS2 existed separately in the resultant catalysts.•NiS2//MoS2 catalyst presented a higher surface area and exposed more active sites.•Both methylcyclohexane selectivity and deoxygenation degree on NiS2//MoS2 catalysts were enhanced.•The hydrodeoxygenation mechanism was well explained by the Remote Control model via spillover hydrogen.NiS2//MoS2 catalysts with different Ni/Mo molar ratios were prepared by two-step hydrothermal method, i.e., MoS2 was firstly synthesized and then NiS2 was prepared and deposited on the surface of MoS2. The resultant catalysts were characterized by XRD, XPS, TEM, SEM, N2 physisorption and their activities were tested using the hydrodeoxygenation of p-cresol as a probe. The results showed that separated NiS2 and MoS2 phases rather than Ni–Mo–S phase existed in NiS2//MoS2 catalysts. In the HDO of p-cresol, NiS2 acted as a donor phase to provide spillover hydrogen, which migrated to MoS2 for reaction. Because of the particular synthesis procedure, NiS2//MoS2 had higher surface area to expose more active sites. When Ni/Mo molar ratio was adjusted to 0.3, p-cresol conversion and the deoxygenation degree reached to 98.5% and 95.4% at 275 °C for 4 h, respectively. The hydrogenation activity was enhanced in the presence of NiS2, leading to the increases on both methylcyclohexane selectivity and deoxygenation degree. NiS2//MoS2 catalysts prepared by this two-step synthesis method exhibited higher hydrodeoxygenation activity than that by other methods, presenting a good potential of this method for the synthesis of other bi-component sulfides with high catalytic activity.NiS2//MoS2 catalysts were prepared by two-step hydrothermal method and separated NiS2 and MoS2 phases were presented in the resultant catalysts. In the HDO of p-cresol, because of the large surface area to expose more active sites, these catalysts exhibited higher activity than that synthesized by other methods. Both methylcyclohexane selectivity and deoxygenation degree were enhanced.

A simple, efficient, economic and environmentally-friendly recovery process for large amounts of potassium chloride from blast furnace flue dust (BF flue dust) with an abundant potassium content is developed. This process is mainly composed of water-leaching, purification, decolorization, vacuum evaporation and cooling crystallization. In this study, the basic properties of blast furnace flue dust were identified by X-ray diffraction (XRD), inductively coupled plasma analysis (ICP), and laser granulometry (LG). The purity of the KCl products was analyzed by ICP combined with the sodium tetraphenylborate (Na-TPB) chemical method and XRD. The particle sizes of the KCl products were characterized by LG and SEM. The results showed that the BF flue dust had a good recovery value with a potassium chloride content of 39.58%. After treating the dust by water-leaching and processing the as-prepared eluent via purification, decolorization and vacuum evaporation, the KCl crystal products were obtained with a yield of 72.77%, 79.52% and 71.09% with 0 °C, 5 °C and 10 °C as the cooling crystallization temperature and 2.27, 2.52 and 2.36 as the mass distribution coefficient, respectively. The KCl crystal products exhibited a narrow particle size distribution with a purity of greater than 96.00%.

In this study, bimodal mesoporous MoS2 nanosheets were successfully synthesized by a hydrothermal method. The effect of pH value, pressure, time and temperature in the preparation process of MoS2 on its structure property and catalytic activity were studied in detail. Low pH value and pressure were beneficial for the preparation of a MoS2 nanosheet with a large surface area and narrow bimodal pore distribution, which exposed more effective active sites on the surface and provided suitable space for reactants and products to diffuse in less resistance. But the acceleration hydrolysis of CS(NH2)2 at the low pH value enhanced the formation rate of MoS2 and then weakened the nanosheet structure. In the HDO of p-cresol, MoS2 exhibited high catalytic activity, and the dominant route was direct deoxygenation. After 4 h, both the conversion and deoxygenation degree reached 99.9% at 300 °C, and toluene selectivity was 66.2%. The HDO reaction mechanism could be well explained by the Rim-Edge model. The higher conversion in the HDO of p-cresol on MoS2 depended on the larger surface area and greater number of big pores of the catalyst, while the higher direct deoxygenation activity of MoS2 depended on the greater number of layers in its stacks.

To improve the dispersity of the emulsion phase in an emulsion liquid membrane (ELM) system, a modified rotating disc contactor (MRDC) was developed. Then, the Sauter mean diameter (d32) of emulsion drops and their drop size distribution were measured by photographic method and analyzed by an image processing program in MATLAB. The effects of rotating speed, flow ratio, total flow, stirring paddle width and surfactant concentration on the drop size and its distribution were studied. The results show that, with the increase in the rotating speed and the paddle width, the degree of turbulence was enhanced which led to the reduction in the drop size. Meanwhile, membrane breakage increased with the turbulent fluctuation, which resulted in the leakage of the internal phase. Fortunately, the membrane breakage could be prevented by a suitable increase in the surfactant concentration. In addition, the drop size decreased with the increase in the surfactant concentration. Besides, the increase in the emulsion phase flow obviously increased the drop size, whereas the increase in the continuous phase flow induced the entrainment of small drops. An empirical correlation for the prediction of the d32 was established with an average absolute relative error (AARE) of 4.1%. The drop size distribution based on the drop volume was accurately fitted with a normal distribution, and its probability density function parameters (α and β) were well predicted by the dimensionless correlations, with the AAREs of 4.2% and 5.9%, respectively.

An Ni–P–B amorphous nano-catalyst was synthesized using a facile chemical reduction method. The amorphous degree was enhanced and the transferred electron decreased with an increase of P content in Ni–P–B. In the hydrodeoxygenation (HDO) of p-cresol, the conversion using Ni–P–B was high up to 98.9% with a selectivity of 6.5% for toluene and a deoxygenation degree of 96.8% at 498 K.

Ni–Mo–S catalysts were prepared by sodium dodecyl benzene sulfonate (SDBS) assisted hydrothermal synthesis. The presence of SDBS increased the NiS2 crystallite size, enlarged the interlayer distance of MoS2 plane and formed loose flower-like architecture, which contributed to the enhanced HDO activity. Compared with Ni–Mo–S synthesized in the absence of SDBS, p-cresol conversion, methylcyclohexane selectivity and deoxygenation degree was increased by 24%, 25.1% and 26.3%, respectively.

MoS2 catalysts were synthesized by hydrothermal method using ammonium heptamolybdate and thiocarbamide as materials, focusing on the effects of the addition of surfactants (such as hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, and sodium lauryl benzenesulfate) during the MoS2 catalyst preparation on their structure and activity in the hydrodeoxygenation (HDO) of 4-methylphenol. The addition of surfactant not only increased the surface area of MoS2, but also changed its microstructure in the stack layer. Compared with Mo—S prepared without any surfactant, Mo—S—DB, Mo—S—CT, and Mo—S—PV exhibited higher activity in the HDO of 4-methylphenol. According to the characterization and catalytic activity results, the structure–activity relation was revealed, and the HDO mechanism of 4-methylphenol on these catalysts was well illustrated by the Rim–Edge model. The HDO of 4-methylphenol on these MoS2 catalysts proceeded with two parallel routes (HYD and DDO), and their selectivity depended on its layer number in the stacks.

•Mesoporous Al2O3 was synthesized by improved precipitation method.•Al2O3 possesses large surface area (412 m2/g) and big pore diameter (19.2 nm).•Large surface area enhances the dispersion of active species.•Big pore diameter improves the diffusion rate of reactants and products.Mesoporous Al2O3 was synthesized using aluminum sulfate as an inorganic precursor and ammonia water as the pH adjustor, adopting the strong chemical and mechanical effects of ultrasound, improving the washing method and adding surfactant in the precursor. The resulting materials were characterized by FT IR, XRD, N2 physisorption, TEM and TG–DTA, which revealed the mesoporous Al2O3 had large surface area (412 m2/g), pore volume (2.3 cm3/g), pore diameter (19.2 nm) and high thermal stability (up to 1000 °C). As the supports for NiMo-based sulfide catalysts in the hydrodeoxygenation (HDO) of p-cresol, the good mesoporous structure of the Al2O3 support resulted in the high dispersion of active species and the rapid diffusion of reactants and products in the pores, hence, improved the HDO activity of NiMoS/Al2O3 catalysts. This synthesis method possesses a great potential for the preparation of support with large surface area and large pore diameter.Graphical abstractMesoporous Al2O3 with large surface area (412 m2/g), large pore volume (2.3 cm3/g), large pore diameter (19.2 nm) and high thermal stability (up to 1000 °C) was prepared adopting the strong chemical and mechanical effects of ultrasound, improving the washing method and adding surfactant in the precursor to. NiMoS supported on these mesoporous Al2O3 exhibited high activity in the hydrodeoxygenation of p-cresol.

Titania–alumina supports were prepared successfully using the ultrasound-assisted precipitation method. The resulting supports were characterized by fourier transform infrared analysis (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and N2 physisorption. The effects of precipitants, washing method and the addition of surfactant CTAB were studied. The supports prepared with NH4HCO3 showed better textural properties compared with that with NH3·H2O, which was attributed to the low NH4+ release rate of NH4HCO3. TiO2–Al2O3 support with SBET = 283 m2/g, Vp = 2.34 mL/g and Dp = 33.0 nm was obtained with this modified precipitation method.Research highlights▶ A new method for preparation of TiO2–Al2O3 support with high surface area and large pore diameter was developed. Ultrasound was introduced into the preparation of support. The water in as-prepared precipitate was replaced with anhydrous ethanol and then CTAB was added in as-prepared support before drying. ▶ TiO2–Al2O3 support with SBET = 283 m2/g, Vp = 2.34 mL/g and Dp = 33.0 nm was obtained with this modified precipitation method. ▶ This modified precipitation method was also suitable for the preparation of other supports such as TiO2, Al2O3, ZrO2 and ZrO2–Al2O3 with high surface area and large pore diameter.

Ni–W–B and La–promoted Ni–W–B amorphous catalysts were prepared by chemical reduction and applied within the hydrodeoxygenation (HDO) of phenol. The resulting catalysts were characterized by surface area, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results showed that some of the electrons were transferred from B0 to Ni0 in Ni–W–B amorphous catalyst. La promoted the reduction of Ni2+ to Ni0 and increased the WO3 content on the catalyst surface. Adding appropriate La in Ni–W–B amorphous catalyst improved the amorphous degree of the catalyst, but excess amounts of La covered some active sites and decreased the catalyst surface area. The HDO of phenol on these amorphous catalysts proceeded via the hydrogenation–dehydration route, leading to no benzene in the products, which could meet the standard of clear fuel in European regulation. La–Ni–W–B amorphous catalysts exhibited higher activities in the HDO of phenol than Ni–W–B amorphous catalyst.

Co–Mo–O–B amorphous catalysts were prepared by the chemical reduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The hydrodeoxygenation (HDO) properties of these catalysts were tested using phenol as the model compound. The catalyst preparation time had no influence on their amorphous structure but a great effect on the catalyst surface composition and the HDO activity. With the prolongation of preparation time, the catalyst particle size and the relative content of Co on the catalyst surface were increased gradually. The conversion of phenol could be as high as 100% with a selectivity of 99.6% for deoxygenation. The aromatics content in the products could be decreased to below 2% and the total H/C atomic ratio could be improved to 1.98. The pseudo first-order reaction rate constant of the phenol transformation on Co–Mo–O–B amorphous catalyst was high to 0.67 mL/(g catalyst s). The main reaction route in the HDO of phenol on Co–Mo–O–B amorphous catalyst proceeded with hydrogenation–dehydration rather than direct hydrogenolysis.

Different contents of promoter (Co) in Co–Ni–Mo–B amorphous catalysts were prepared by chemical reduction of the precursors of metal salts with a sodium borohydride aqueous solution. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Adding a proper content of the promoter Co into Ni–Mo–B amorphous catalyst could increase the MoO2 content and decrease the particle size, but doping excess Co would cover some of the active sites and increase the particle size of the catalysts. The effect of Co content on the catalytic hydrodeoxygenation activity of the amorphous catalysts was studied using phenol as a model compound. The main route for the HDO of phenol on these amorphous catalysts was hydrogenation–dehydration and the content of aromatic compounds in HDO products was decreased obviously. The pseudo first-order reaction rate constant of the phenol HDO on Co–Ni–Mo–B amorphous catalyst was much greater than that of MoS2 when adding proper promoter Co.

The amorphous Ni–Mo–B catalysts were prepared by ultrasonic as well as regular chemical reduction and characterized by BET, SEM, XRD, XPS, and FTIR. Their catalytic activity in the hydrodeoxygenation of phenol was evaluated. The influences of the catalyst preparation conditions and the reaction temperature on the phenol hydrodeoxygenation were investigated, and a reaction mechanism was proposed. The results showed that the particle size, agglomeration phenomenon, surface area, and MoO2 and B content of the Ni–Mo–B catalysts can be regulated by introducing the ultrasonic treatment into the chemical reduction, which is effective to enhance their catalytic activity in phenol hydrodeoxygenation. At 498 K, the conversion of phenol is 81.08% and the hydrodeoxygenation selectivity reaches 93.39%.

Ni–Mo–B amorphous bimetallic catalysts were prepared by chemical reduction of nickel nitrate and ammonium heptamolybdate with sodium borohydride aqueous solution. By introducing the ultrasound, the particle size was decreased and the formation of boron oxide was inhibited. The catalyst, prepared by ultrasonic-assisted reduction, exhibited higher catalytic activity than the normal amorphous catalysts prepared via direct reduction in the phenol hydrodeoxygenation (HDO). The higher catalytic activity could be attributed to the higher contents of Mo4+ and unsaturated Ni active site.

Ni–Mo–B amorphous catalysts promoted by Co and La were prepared by chemical reduction of the corresponding metal salts with sodium borohydride. The effects of additives for the catalytic activity were studied using the hydrodeoxygenation of phenol as model reaction. Co- and La-promoted Ni–Mo–B amorphous catalysts exhibited higher catalytic activity. The total selectivity of oxygen-free products was increased to 93.1% with a selectivity of 3.2% aromatics on Co–Ni–Mo–B and the total H/C atomic ratio in the products was improved to 1.99 on La–Ni–Mo–B.

Ni–Co–W–B, Ni–W–B and Co–W–B catalysts were prepared by chemical reduction method and showed high activity in the HDO of cyclopentanone. Co–W–B had higher thermal stability than Ni–Co–W–B and Ni–W–B catalyst. The conversion of cyclopentanone could be high to 96.6% with a cyclopentanol selectivity of 0.4% and a deoxygenation rate of 95.4%. The HDO activity of the catalyst was related to its thermal stability, surface area, hydrogen supplying ability and Brönsted acid sites.Ni(Co)–W–B amorphous catalysts exhibited high catalytic activity in the hydrodeoxygenation of cyclopentanone.The hydrodeoxygenation of cyclopentanone on Co–W–B amorphous catalyst at 548 K.Download full-size imageResearch Highlights► Ni(Co)–W–B amorphous catalysts were prepared with chemical reduction method. ► Ni(Co)–W–B amorphous catalysts were applied into the HDO of cyclopentanone. ► The cyclopentanone conversion was high to 96.6% with a deoxygenation rate of 95.4%. ► The catalyst activity depended on its thermal stability and Brönsted acidity.