Two new lead rare-earth polyborates, PbTbB7O13 and PbEuB7O13, have been successfully synthesized via a high temperature molten salt method. Single crystal X-ray diffraction analysis reveals that they are isostructural and feature a 2D layer structure that contains alternating layers of [B7O13]∞ and [Tb]∞. The [B7O13]∞ layer is constructed of BO3 and BO4 groups with the fundamental building block of B7O17 (3Δ4□: <Δ2□>Δ<Δ2□>). Solid solutions of PbTb1−xEuxB7O13 (x = 0–1) were prepared via a solid state reaction and the photoluminescence properties were studied. The results show that under UV or near-UV excitation, the luminescence colour of samples of PbTb1−xEuxB7O13 (x = 0–1) can be tuned from green through yellow to red by simply adjusting the relative Eu3+ and Tb3+ concentrations, because of the Tb3+ → Eu3+ energy transfer mechanism.

Two new lead rare-earth polyborates, PbTbB7O13 and PbEuB7O13, have been successfully synthesized via a high temperature molten salt method. Single crystal X-ray diffraction analysis reveals that they are isostructural and feature a 2D layer structure that contains alternating layers of [B7O13]∞ and [Tb]∞. The [B7O13]∞ layer is constructed of BO3 and BO4 groups with the fundamental building block of B7O17 (3Δ4□: <Δ2□>Δ<Δ2□>). Solid solutions of PbTb1−xEuxB7O13 (x = 0–1) were prepared via a solid state reaction and the photoluminescence properties were studied. The results show that under UV or near-UV excitation, the luminescence colour of samples of PbTb1−xEuxB7O13 (x = 0–1) can be tuned from green through yellow to red by simply adjusting the relative Eu3+ and Tb3+ concentrations, because of the Tb3+ → Eu3+ energy transfer mechanism.

•Pt/C was identified as the most suitable catalyst.•A synergistic effect existed during the in situ upgrading of the UEO (used engine oil) and microalgae.•Denitrogenation and desulfurization reactions manly occurred at 350–400 °C.•All of the oils have an energy density higher than that of diesel fuel.•The S content of the oil is even below the minimum requirement of China IV diesel.Co-hydrotreating of microalgae (M) and UEO (used engine oil) was examined for the direct production of gasoline and diesel fuels or blending components. The addition of the noble metal catalysts promoted the cracking and in situ hydrogenation of liquid products (oils) and was beneficial for the production of liquid products. Using Pt/C as the catalyst, the effects of temperature (350–450 °C), time (2–6 h), UEO/M mass ratio (6/0–0/6), catalyst loading (1–60 wt.%), and initial H2 pressure (0.1–8 MPa) on the yield and quality of the liquid products were studied. A synergistic effect existed during the co-hydrotreating of the UEO and microalgae, which not only favored the production of liquid products but also promoted in situ denitrogenation and deoxygenation. Co-hydrotreating produced an upgraded oil with fuel properties (e.g., density, calorific value) comparable to traditional liquid transportation fuels derived from fossil fuel. The S content (45 ppm) of the upgraded oil produced at 450 °C is even below the minimum requirement of China IV diesel (50 ppm). Examination of the composition of the upgraded oils showed the formation of dominant light aliphatic and aromatic hydrocarbons that could also be used as a chemical feedstock.

•Hydropyrolysis and co-hydropyrolysis of algae and UEO were examined.•Co-hydropyrolysis showed many advantages relative to the hydropyrolysis.•Co-hydropyrolysis favored the production of light-end products.•All of the pyrolysis oils flowed well and have a viscosity of 8.0 mPa s.•Approximately 85% of the pyrolysis oils were composed of saturated hydrocarbons.The catalytic hydropyrolysis and co-hydropyrolysis of algae (microalgae and macroalgae) and used engine oil (UEO) for the production of potential fuels for automobiles were examined. The co-hydropyrolysis of algae and UEO produced oils that possessed slightly higher H and C content, a higher H/C atomic ratio, and an extensively reduced heteroatom (59.78–75.62% for O, 6.98–81.65 for N, and 43.30–86.41 for S) content and O/C atomic ratio compared to the oils that were obtained via the hydropyrolysis of algae, with the exception of oil produced from UEO and Schizochytrium limacinum (SL). The co-hydropyrolysis of microalgae and UEO was found to decrease the amounts of saturated hydrocarbons and aromatics present in the oils compared with the hydropyrolysis of the microalgae, except for SP. By contrast, the co-hydropyrolysis of macroalgae and UEO resulted in an increased number of saturated hydrocarbons and a decreased aromatic content in the oils compared with the hydropyrolysis of the macroalgae, except for LM. The co-hydropyrolysis of algae and UEO also led to increased energy recovery ranging from 80.19 to 91.26% compared with the hydropyrolysis of algae ranging from 53.25 to 79.58%. All of the pyrolysis oils flowed well and had similar viscosities of approximately 8.0 mPa s.

•Facile synthesis from commercial fiber and detailed characterization at all stages.•Highly tandem catalytic activity and mild reaction conditions.•Excellent recyclability and stability reused without activation and protection.•Extremely simple separation procedure and efficient lager-scale process.A potential industrialized fiber catalyst for “click chemistry” via the one-pot multicomponent Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) for the synthesis of 1,2,3-triazoles in water, is reported. Detailed characterization by appearance, mechanical properties, elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber catalyst during the preparation and utilization processes. Moreover, the fiber catalyst-mediated reactions proceeded smoothly to afford triazoles with nearly quantitative yields in short time (15 min). Furthermore, the fiber catalyst has shown tandem activities and superior recyclability (over 10 cycles), and the procedure is operationally simple and amenable to the gram-scale on a simple fixed-bed reactor.Download high-res image (113KB)Download full-size image

•Hydrothermal liquefaction of duckweed was performed at 350 °C for 30 min.•Effect of extraction solvents on the yields and composition of bio-oils was examined.•The polar solvents extracted higher gravimetric yields.•Polarity and molecular structure of solvent affect the composition of the bio-oils.•Polar solvents provided higher yields and ER of the bio-oils than the nonpolar solvents.The influence of the extraction solvents on the yields of the product fractions and on the composition of the bio-oils obtained from the hydrothermal processing of duckweed at 350 °C for 30 min was investigated. Ten solvents were employed including polar solvents (isopropanol, ethyl acetate, dichloromethane, diethyl ether, dichloroethane, benzene, carbon disulfide) and nonpolar solvents (cyclohexane, n-hexane and petroleum ether). The extraction solvents with high relative polarity values tended to produce higher yields of the bio-oils. The highest bio-oil yield of 26 ± 1 wt.% was obtained using isopropanol, followed by dichloromethane (24 ± 1 wt.%). Nonpolar solvents including cyclohexane, n-hexane, and petroleum ether produced the yields of the bio-oils ranging from 3 ± 0.2 to 9 ± 0.4 wt.%. The bio-oils always had a significantly higher C and H contents and a substantially lower O and S contents than those of the biomass material. The C and H contents of the bio-oil from nonpolar solvents, which averaged 78 ± 0.8 wt.% and 10 ± 0.5 wt.%, respectively, were slightly higher than the values from the polar solvents, which averaged 75 wt.% and 9 wt.%, respectively. In contrast, the N and O contents of the bio-oils from nonpolar solvents was lower than that from the polar solvents. The energy recovery (ER) obtained from the polar solvents varied from 42 ± 2 to 60 ± 3%, which is much higher than the ER obtained from the nonpolar solvent (24 ± 1% for cyclohexane) and lowest (10 ± 0.5% for n-hexane). Significant differences in molecular composition were observed in the bio-oils when varying the solvent, and these differences were attributed to the combined effects of the polarity and the molecular structure of each solvent.

In the present work, crude bio-oil derived from the hydrothermal liquefaction (HTL) of duckweed (Lemna sp.) was treated in subcritical water at different reaction environment (H2,CO), temperature (330–370 °C), time (2,4 h), and Pt/C sulfide (Pt/C–S) catalyst loading (0–20 wt %), aiming to find how these parameters affect the products yield and properties of the treated oil. The results demonstrated that treating the crude duckweed bio-oil in subcritical water with or without catalyst under either H2 or CO environment effected several desirable changes in the oil. Compared to H2, using CO as initial gas led to treated oil with higher yield, lower viscosity, and higher hydrogen, and could also achieve larger energy recovery. Higher temperatures and longer reaction times produced treated oil with better quality but at the expense of reducing oil yield, respectively, due to the increased coke and gas formation. Larger catalyst loading was also favorable in realizing high quality treated oil, but it also promoted the production of coke and water-soluble material. During the treatment, the oxygenates in the crude duckweed bio-oil were more reactive than that of the nitrogenates, especially with catalyst. The higher heating values of the treated oils were estimated within the range 34.3–38.2 MJ/kg. CO2 was the dominant gas formed under either CO or H2 environment. Thus, this study suggested that the crude bio-oil from the HTL of duckweed can be effectively upgraded in subcritical water.

•Hydro-pretreatment can reduce the viscosity and heteroatom contents of crude oil.•MCM-41 provided the highest upgraded bio-oil yield of 54.5 wt.%.•All of the zeolites promoted the denitrogenation, deoxygenation, and desulfurization.•Zeolite can also accelerate the cracking reaction of the pretreated oil.•The upgraded oil mainly consisted of hydrocarbons.We report the catalytic hydrothermal upgrading of pretreated algal bio-oil. The reaction was performed at 400 °C for 240 min with the addition of 6 MPa H2 and 10 wt.% zeolite catalyst in supercritical water (ρH2O = 0.025 g/cm3). Nine zeolites (Hβ, HZSM-5 (SiO2/Al2O3 = 25:1), HZSM-5 (SiO2/Al2O3 = 50:1), HZSM-5 (SiO2/Al2O3 = 170:1), HY (5% Na2O), HY (0.8% Na2O), SAPO-11, MCM-41 (50% Si), and MCM-41 (100% Si) were screened to investigate their effects on the yields of the product fraction and the properties (e.g., elemental composition and heating value) of the upgraded bio-oil. The catalyst type affected the yields of the product fractions: SAPO-11 produced the lowest upgraded bio-oil yield of 42.4 wt.%, and MCM-41 provided the highest yield of 54.5 wt.%. Compared with non-catalytic upgrading reactions, all of the zeolites promoted the denitrogenation, deoxygenation, and desulfurization of the pretreated bio-oil due to the presence of acid sites. HY (5% Na2O), HY (0.8% Na2O), and HZSM-5 (SiO2/Al2O3 = 25:1) showed the highest activity toward denitrogenation, deoxygenation, and desulfurization, respectively. The upgraded bio-oil mainly consisted of hydrocarbons, accounting for 80% in total and as high as 95.6% of the fraction below 400 °C.Download high-res image (122KB)Download full-size image

Two new lead rare-earth polyborates, PbTbB7O13 and PbEuB7O13, have been successfully synthesized via a high temperature molten salt method. Single crystal X-ray diffraction analysis reveals that they are isostructural and feature a 2D layer structure that contains alternating layers of [B7O13]∞ and [Tb]∞. The [B7O13]∞ layer is constructed of BO3 and BO4 groups with the fundamental building block of B7O17 (3Δ4□: <Δ2□>Δ<Δ2□>). Solid solutions of PbTb1−xEuxB7O13 (x = 0–1) were prepared via a solid state reaction and the photoluminescence properties were studied. The results show that under UV or near-UV excitation, the luminescence colour of samples of PbTb1−xEuxB7O13 (x = 0–1) can be tuned from green through yellow to red by simply adjusting the relative Eu3+ and Tb3+ concentrations, because of the Tb3+ → Eu3+ energy transfer mechanism.

Two new lead rare-earth polyborates, PbTbB7O13 and PbEuB7O13, have been successfully synthesized via a high temperature molten salt method. Single crystal X-ray diffraction analysis reveals that they are isostructural and feature a 2D layer structure that contains alternating layers of [B7O13]∞ and [Tb]∞. The [B7O13]∞ layer is constructed of BO3 and BO4 groups with the fundamental building block of B7O17 (3Δ4□: <Δ2□>Δ<Δ2□>). Solid solutions of PbTb1−xEuxB7O13 (x = 0–1) were prepared via a solid state reaction and the photoluminescence properties were studied. The results show that under UV or near-UV excitation, the luminescence colour of samples of PbTb1−xEuxB7O13 (x = 0–1) can be tuned from green through yellow to red by simply adjusting the relative Eu3+ and Tb3+ concentrations, because of the Tb3+ → Eu3+ energy transfer mechanism.