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[Display omitted] • A comprehensive review of biomass catalytic conversion over Nb-based catalysts. • Properties of various Nb-based catalysts are summarized. • Systematic reaction routes for biomass catalytic conversion are evaluated. • Advantages on the application of Nb-based catalysts are discussed. • Future research on bioenergy production over Nb-based catalysts is proposed. Catalytic conversion of biomass to fuels and chemicals has attracted considerable attention in addressing the global challenges associated with energy and environmental crisis. Catalyst plays a crucial role in the biomass conversion process, and the characteristic of catalysts are continuously improved to meet the requirements. Niobium (Nb) based catalysts, generally in the form of niobic acid, niobium pentoxide (Nb 2 O 5), niobium phosphate (NbOPO 4), and their supporting materials, have been widely employed for bioenergy production. This review summarizes the special characteristics of Nb-based catalysts, and the application of these catalysts on the catalytic conversion of biomass, including (I) properties of Nb-based catalysts, (II) catalytic hydrolysis/dehydration for platform chemicals, (III) catalytic pyrolysis for hydrocarbons, (IV) catalytic esterification, (V) catalytic hydrogenation, and (VI) catalytic oxidation. The Nb compounds become an attractive candidate in the bioenergy field, and this review serves as a basis for future research on biomass catalytic conversion over Nb-based catalysts. [ABSTRACT FROM AUTHOR]

Chloride ion significantly impacts the degradation efficiency of organic pollutants in chemical industrial wastewater during electrocatalytic process, therefore utilization of Cl− to in situ produce reactive chlorine species (RCS) is desired for electrocatalytic degradation of pollutants. We developed a novel catalyst by incorporating Zn into CoO x (Zn n CoO x) as anode for the electrocatalytic removal of 4-chlorophenols (4-cp) in Cl−-containing wastewater. Characterization and electrochemical performance of Zn n CoO x catalysts indicated that Zn incorporation increased Co2+/Co3+ ratio, resulting in lattice distortion and the formation of oxygen vacancy (O V). Electrocatalytic experiments showed that Zn 2 CoO x (i.e., ZnCo = 2:1) had the highest electrochemical reactivity, and the 4-cp degradation rates (k obs) showed a positive correlation with O V. The identified reactive species involved in 4-cp degradation included O 2 •− and RCS. The formation mechanism of reactive species and the degradation pathways of 4-cp during electrocatalytic process using the Zn 2 CoO x anode were proposed. Overall, the developed Zn n CoO x catalyst as anode can utilize Cl− to in situ produce RCS and exhibit an effective performance on the 4-cp degradation in Cl−-containing wastewater. • Zn incorporation increased Co2+/Co3+ ratio, resulting in the formation of O V. • Zn 2 CoO x had the highest electrochemical activity and electrocatalytic performance. • The k obs values of 4-cp showed a positive correlation with O V. • The identified reactive species involved in 4-cp degradation included O 2 •− and RCS. [ABSTRACT FROM AUTHOR]

MIL-100(Fe), a kind of iron-based metal-organic framework materials (MOFs), can be synthesized at room temperature or hydrothermal conditions, which are promising precursor materials for preparing photocatalysts to degrade some recalcitrant chlorophenols in industrial wastewater. However, the relationship between the structural characterization of MIL-100(Fe) derivatives and their photodegradation behavior of chlorophenol pollutants is still unclear. Thus, in this work, a porous Z-scheme α-Fe 2 O 3 /MIL-100(Fe) composite was successfully fabricated via partial-pyrolysis of MIL-100(Fe) precursor synthesized through green synthesis route, which was further used for degrading high-concentration of 2,4-dichlorophenol under visible-light illumination (λ > 420 nm). The effects of synthesis route and pyrolysis temperature of MIL-100(Fe) on the degradation efficiencies of as-derived materials for 2,4-dichlorophenol were investigated. The structure-activity relationship was illuminated in detail. Otherwise, the influence of several process factors, i.e., initial concentration and pH of the 2,4-dichlorophenol solution, catalyst dosage on the degradation efficiency of 2,4-dichlorophenol has also been performed. The removal efficiency of 2,4-dichlorophenol with the initial concentration of 100 mg L−1 reached up to 87.65% under optimized conditions. Lastly, the possible mechanism was explored based on trapping experiments and some other characterization results. The study in this paper not only exhibited new insight into the modified α-Fe 2 O 3 material with high photocatalytic activity but also provided a promising method for treating wastewater containing 2,4-dichlorophenol or other similar organic pollutants. [Display omitted] • Fabricated Z-type α-Fe 2 O 3 /MIL-100(Fe) material via partial-pyrolysis of MIL-100(Fe). • MIL-100(Fe) precursor was obtained via a green and energy-saving synthesis route. • Synthesis routes of MIL-100(Fe) affected the photodegrade activity for 2,4-DCP. • Pyrolysis temperatures of MIL-100(Fe) also affected the photocatalytic activity. • The structure-activity relationship of α-Fe 2 O 3 /MIL-100(Fe) was illuminated. [ABSTRACT FROM AUTHOR]

• Fabrication of sub-micro Si/Sn@SiO x -C composite by a facile milling and annealing process without any by-products. • Nano-SnO 2 was in-situ reduced to metallic Sn via ball-milling with micrometer Si. • The prepared composite delivers excellent rate capability and cyclability. • The superior performance is derived from introduction of sn with high electronic conductivity, dual-buffering of inner SiO x matrix and surface carbon layer. Micrometer silicon (MSi) particles are prospective anode material for high energy-density lithium-ion batteries. Aiming at the scale-up production and the improvement in rate capability, a novel sub-micro Si/Sn@SiO x -C (SSSC) composite via a facile two-step process of milling and annealing is designed and synthesized. With the structural uniqueness including in-situ introduction of metallic tin (Sn) originated from mechano-reduction of nano tin dioxide (nano-SnO 2) with MSi, dual-buffering of inner SiO x matrix and uniform surface carbon layer, SSSC electrodes exhibit impressive rate capability and stable cyclability. The optimum architecture of SSSC-73 (i.e. weight ratio of precursor MSi-to-SnO 2 is 7:3) delivers stable cycling with 1102 mAh g −1 (at 0.5 A g −1) over 100 cycles and exceptional rate performance with a high capacity retention of 95% over 500 cycles at 2 A g −1. Particularly, this facile and cost-effective preparation of SSSC composites has no by-products, making it competitive in practical application. A sub-micro Si/Sn@SiO x -C composite was in-situ mechanochemically synthesized by a combinational milling and annealing method and exhibit excellent high-rate performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrochromic (EC) smart window can dynamically alter optical property under the electric field, showing great potential in building energy conservation. Nickel oxide (NiO) acts as one of the most promising EC candidates while suffering insufficient reaction sites and low electrical conductivity. Herein, we introduced Mn2+ ions into NiO for the heteroatom doping towards improved EC performance. As expected, NiO–Mn–3 film exhibited optimal transmittance modulation (81.8 %) and fast coloring/bleaching time (3.5/5.1 s), which were considerably related to the improved specific surface area and increased electronic conductivity. Electrochemical characterization confirmed that the enhanced ions diffusion coefficient and lowered resistance delivered a positive impact on boosting the EC property. Mott–Schottky study also confirmed that the heteroatom doping effectively increased the carrier concentration. Our results not only provided important insight into a promising electrode material for EC energy–saving application, but also offered an economic and effective synthetic strategy for other doped metal oxide films. [Display omitted] • Mn2+ was introduced into NiO for the heteroatom doping by a CBD method. • The doped sample with reserved porous structure exhibited enhanced conductivity. • The heteroatom doping delivered a positive impact on boosting the EC property. • Mott–Schottky study confirmed that doping increased the carrier concentration. [ABSTRACT FROM AUTHOR]

Abstract Phenol is a typical aromatic organic byproduct in the coking industry, which can be also as a raw material for producing some useful chemicals by catalytic hydrogenation. In this paper, by constructing carbon/ZrO 2 porous support with abundant vacancies for loading nickel and cobalt nanoparticles (i.e., Ni x Co y @C/ZrO 2) with using Zr-based metal organic frameworks as the precursor, the significant phenol converting enhancement in both hydrothermalcatalytic activity and stability has been fulfilled. Specially, the physiochemical characteristics of the Ni x Co y @C/ZrO 2 particles have been analyzed, which verified the presence of Ni Co alloy and its high homogeneity and dispersity. The catalytic results showed that the Ni 3 Co 1 @C/ZrO 2 catalyst has the best catalytic performance at the desired temperature of 200 °C for 240 min, and the conversion of phenol is 96.33% while the selectivity of cyclohexanol is 91.14%. Kinetic study showed that the activation energy was only 44.31 kJ/mol, which reflected that the hydrogenation could be easily carried out with Ni 3 Co 1 @C/ZrO 2 catalyst. These findings can provide a good guidance for designing and developing the non-noble-metal catalysts for achieving the industrial utilization of phenol in coking wastewater in the future. Graphical abstract Image 1061 Highlights • Phenol is a typical aromatic organic byproduct of the coking industries. • The Ni 3 Co 1 @C/ZrO 2 catalyst has been prepared. • Phenol can be easily converted into cyclohexanol with Ni 3 Co 1 @C/ZrO 2 catalyst. • The Ni Co alloy and its dispersity play an important role on the selective catalysis. [ABSTRACT FROM AUTHOR]

Producing biodiesel via transesterification of waste oils or fats with short-chain alcohol is one of the possible ways to alleviate global energy and environmental issues, and further reducing the cost of transesterification catalyst is the essential strategy to enhance the competitiveness of biodiesel, such as applying industrial solid wastes as the source of catalyst active species. Thus in this work, via one-step pyrolysis of the calcium-rich residue, a byproduct from the hydrothermal treating (140–180 °C for 2–4 h) of paper mill sludge (PMS), a novel walnut-shaped calcium oxide-cancrinite based catalyst was prepared and applied to the transesterification of waste frying oil. The hydrothermal condition (changed from 140 oC-2 h to 180 oC-4 h) of PMS slightly influenced the yield of fatty acid methyl ester (Y FAME), which ranged from 98.87% to 96.95% due to the slight decrease of the total basicity of strong basic sites (TSB β+γ) from 149.6 to 102.9 μmol g−1. On the contrary, the pyrolysis temperature had a much greater effect on the transesterification performance of obtained catalysts. The optimum pyrolysis temperature was 750 °C and when it was increased to 850 °C, the increased bonding tendency of Si with Ca passivated the activity of calcium species and reduced the basic intensity and basicity of PS C -850, thus lowering its transesterification activity. Besides, the key process parameters were optimized and at the conditions of 70 °C, 3 h, 6.0 wt% of catalyst dosage, 10:1 of molar ratio of methanol to oil, over 95% of Y FAME can be reached. The work herein not only provided a feasible way to recycle the inorganic solid residue of PMS but further lowered the cost of preparing biodiesel. [Display omitted] • The consistency analysis model and algorithm of grinding roundness error of workpiece journal are proposed. • The rationality of the proposed model is verified by experiments. • The Influence of roundness error batch consistency of workpiece journal grinding is studied. [ABSTRACT FROM AUTHOR]

A novel nano/micro-structured pSi@C composite with buffer void was successfully synthesized via a simple and scalable process with combination of the calcination, spray drying, carbonization and HF etching. The obtained pSi@C composite with this particular structure exhibits high reversible capacity of ca. 2200 mA h g −1 and excellent cycling stability with 90.3% capacity retention after 300 cycles, which benefits from its void spaces between silicon and carbon layer and highly conductive carbon-layer. The simple and scalable synthesis technique and good electrochemical performance of this nano/micro-structured pSi@C composite make it a promising candidate for large capacity lithium ion battery anode material. [ABSTRACT FROM AUTHOR]

Abstract: Activation of the MmNi4.03Co0.42Mn0.31Al0.24 hydrogen storage alloy electrode is performed by immersing the electrode in a solution containing 6.0moldm−3 NaOH and 0.1 mol dm−3 NaBH4. The effects of activation on the electrocatalytic activity of the electrode for NaBH4 oxidation are investigated by cyclic voltammetry and chronoamperometry. Immersion activation greatly improves the electrocatalytic activity of the alloy electrode. Hydrogen was absorbed in the alloy during the immersion activation treatment and its electrooxidation is responsible for the high initial oxidation current. The stabilized current mainly results from the direct oxidation starting from the borohydride species. The effects of activation on structure and surface chemistry of the alloy are also discussed. [Copyright &y& Elsevier]

The transesterification of triglycerides is a critical step in biodiesel production. In this work, by loading boron-doped copper oxides onto SBA-15 mesoporous molecular sieve, an acid-base bifunctional catalyst (i.e., CunO-Bs/SBA-15) was prepared and applied to triglyceride transesterification. Compared with pure copper, sodium or boron oxides-based catalysts, CunO-Bs/SBA-15 enabled a higher biodiesel yield (>97.5%) at near room temperature (i.e., 40 °C) in 120 min. The characterization results showed that after B doping, the CunO-Bs/SBA-15 catalyst contained highly-dispersed acid-base sites without blocking the channels of porous SBA-15 support, which had good catalytic performance. Finally, in-situ DRIFTS was used to reveal the catalytic mechanism of the acid-base bifunctional groups of the as-prepared CunO-Bs/SBA-15 during transesterification. [Display omitted] • A boron-doping process was used to synthesize bifunctional Cu–B oxides on an SBA-15 support. • The Cu n O-B s /SBA-15 catalyst showed near-room temperature activity and stability for triglyceride transesterification. • The highly-dispersed boron and copper sites co-increased the efficiency of triglyceride transesterification. • In situ DRIFTS revealed the presence of acidic and basic catalytic pathways on the Cu n O-B s /SBA-15 surface. [ABSTRACT FROM AUTHOR]

Low-rank coals are very abundant in several regions throughout the world. However, it is difficult to use the low-rank coals directly due to their undesirable characteristics such as high moisture, high ash and high oxygen content. The utilization of low-rank coals has received more and more attention with the increase of consumption of other fossil fuels. Besides the pyrolysis and alcoholysis, the conversion of low-lank coals under hydrothermal conditions (including sub-and supercritical water) for high-quality solid fuel, coal liquefied oil and gaseous fuels has also been widely investigated. In this review, the development of low-rank coal hydrothermal upgrading, the liquid fuel production from coal in sub-and supercritical water and supercritical water gasification of coal for hydrogen production, including partial oxidative gasification, homogeneous/heterogeneous catalytic gasification and related kinetic investigations are discussed. In addition, the element transformation such as N, S and metals during the hydrothermal process are also presented. [ABSTRACT FROM AUTHOR]

Biochar derived from waste water hyacinth was prepared and modified by ZnO nanoparticles for Cr(VI) removal from aqueous solution with the aim of Cr(VI) removal and management of waste biomass. The effect of carbonization temperature (500–800 °C), ZnO content (10–50 wt%) loaded on biochar and contact time (0.17–14 h) on the Cr(VI) removal were investigated. It was found that higher than 95% removal efficiency of Cr(VI) can be achieved with the biochar loaded 30 wt% ZnO. The adsorption kinetics of the sorbent is consistent with the pseudo-second-order kinetic model and adsorption isotherm follows the Langmuir model with maximum adsorption capacity of 43.48 mg g −1 for Cr(VI). Multiple techniques such as XRD, XPS, SEM, EDX and FT-IR were performed to investigate the possible mechanisms involved in the Cr (VI) adsorption. The results show that there is precipitation between chromium ions and Zn oxide. Furthermore, the ZnO nanoparticles acts as photo-catalyst to generate photo-generated electrons to enhance the reduction of Cr(VI) to Cr(III). The as-prepared ZnO/BC possess good recyclability and the removal ratio remained at about 70% in the fifth cycle, which suggests that both contaminants removal and effective management of water hyacinth can be achieved by the approach. [ABSTRACT FROM AUTHOR]

The exploration of non-noble-metal catalysts for high efficiency gasification of biomass in supercritical water (SCW) is of great significance for the sustainable development. A series of Ni–M (M = Co or Zn) bimetallic nanoparticles supported on graphitized carbon black were synthesized and examined as catalysts for gasification of phenol in SCW. It was found that a nearly complete gasification of phenol can be achieved even at a low temperature of 450 °C with the bimetallic nanoparticles catalysts. Kinetic study indicated the activation energy for phenol gasification were 20.4 ± 2.6 and 43.6 ± 2.6 kJ/mol for Ni 20 Zn 15 and Ni 20 Co 15 catalyst, respectively. XRD, XPS and TEM were further performed to characterize the catalysts and the results showed the formation of NiCo and NiZn alloy phase. Catalyst recycling experiments were also conducted to evaluate the stability of the catalysts. The characterization of used catalysts suggest that the severe agglomeration of nanoparticles leads to the decrease in catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The yield of high-efficiency conversion of biomass to furfural was 90.5%. • The ultra-high specific surface area of Fe@BC RSS -SO 3 H can provide abundant reaction sites. • The Lewis acid strength of the metal ion is conducive to the dehydration of xylose to furfural. • The water molecules can promote the ring-opening dehydration of xylose molecules. • The GBL molecules can prevent the degradation of furfural by forming a protective layer. In the conversion of lignocellulosic biomass to furfural, a low yield is often obtained due to the natural degradation-resistant structure of the biomass and the high reactivity of the furfural molecule. However, in this study, the efficient conversion of biomass to furfural (90.5 % furfural yield) was achieved by working in the coordination of both carbon-based solid acid catalyst and water-butyrolactone co-solvent system using bagasse pith biomass as feedstock. The solid acid catalyst prepared by loaded sulfonic acid groups and Fe3+ on biochar showed a high specific surface area and well-developed pore channels, which can facilitate the breakdown of the solid structure of bagasse pith and the adequate hydrolysis. Meanwhile, by adjusting the volume ratio of the co-solvent system, the water in the system can not only foster the hemicellulose hydrolysis in bagasse pith but also facilitate the dehydration of xylose to form furfural. Furthermore, it enables the butyrolactone in the system to form a protective layer around the furfural molecule in time to avoid the degradation condensation reaction of the furfural molecule in the acidic system. Eventually, the 90.5 % furfural yields were obtained at water-butyrolactone volume ratio, reaction temperature, and reaction time were 1:29, 190, and 3 h, respectively. [ABSTRACT FROM AUTHOR]

Hydrogenation of phenol was investigated in a high-temperature water (HTW) system. The characterization of the catalyst used in the system was investigated by BET surface area, XRD, XPS, and TEM testing methods. The results indicated that phosphotungstic acid (PTA) modified Pd/Ce-AlO x catalyst, i.e., Pd/W-Ce-AlO x , could not only increase the values of binding energy of the major elements and thus enhance its ability in attracting electrons, but also enhance the phenol degradation and selectivity in HTW when comparing with non-PTA modified catalysts. The Pd/W-Ce-AlO x catalyst also showed a high activity for the phenol hydrogenation and high selectivity at a moderate temperature (180 °C) in HTW system, because cyclohexanone is the major products (more than 95%) from the reaction. However, at the temperatures greater than 260 °C, the changes of transport properties would increase the dissociation of cyclohexanone from the acidic sites, which resulted in the future reactions with hydrogen to form cyclohexanol rather than cyclohexane. Based on the observation, a kinetic model of detail pathways to give the insight views was proposed. The model confirmed that at higher temperatures over 260 °C, the reactions to form cyclohexanol, benzene and cyclohexane increased dramatically. In the presence of Pd/W-Ce-AlO x catalyst, the formation of benzene can be effectively suppressed. Therefore, PTA modified catalysts have a great potential to improve the hydrogen selectivity of phenol in the HTW system. [ABSTRACT FROM AUTHOR]

Finding a more efficient method for the transesterification of triglycerides to biodiesel fuel (BD) is important in today’s world. In this study, transesterification of trilaurin was carried out in a solution containing 4 wt% of the Lewis acid AlCl 3 dissolved in a cosolvent of ethanol and 5 MPa CO 2 . A conversion rate of over 90% was achieved within 1 h at the low temperature of 180 °C. The process indicates a co-catalytic effect of the Lewis acid and CO 2 . We postulate several key steps for the mechanism. First, the CO 2 –ethanol mixture enhances the hydrogen bonding, increasing the concentration of C 2 H 5 O . Second AlCl 3 attacks the oxygen of C O C to weaken the bonds to form carbonyl carbon OR1, which is then easily attacked by C 2 H 5 O to give the transesterified product (C 2 H 4 COOR1). Third, AlCl 3 is finally replaced by H to form glycerin (GL) and intermediates, such as unmethyl esterified compounds (uME). AlCl 3 was used as a flocculant and catalyst for converting waste cooking oil (WCO) to BD. The process achieved 97% free fatty acid (FFA) conversion at 120 °C in 90 min, making it one of the most efficient systems available for WCO recovery. AlCl 3 was also successfully applied to microalgae, signaling the potential for a process that combines harvesting, lipid extraction, and transterification, leading to fully integrated, microalgae-based BD production. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDH) was proved as preferable retardants for lignocellulosic materials. In this study, Mg/Al-LDH was selected and one-step modified by GP which exhibited superior characteristics of flame retardancy and non-toxicity. Results showed that more complete two-dimensional layered structure with suitable crystal particle size was formed for GP modified LDH. Specifically, GP 3 -LDH not only enhanced the thermal stability of cellulosic composites, but also assisted the peak heat release rate (PHRR) and total heat release (THR) in declining 42.5% and 22.7% compared with those added with non-modified Mg/Al-LDH. In addition, the limiting oxygen index (LOI) achieved as high as 27.7% with 15 wt% addition, indicating the successful modification with GP for outstanding flame-retardant performance, low addition and controlled strength of cellulosic composites. [Display omitted] • GP was inserted into the interlayer of LDH through simple one-step modification. • Two-dimensional crystalline structure with suitable crystal particle size was formed. • The outstanding flame-retardancy and controlled strength exhibited with low addition. [ABSTRACT FROM AUTHOR]

Abstract: Au/Ni-foam electrodes with three dimensional network structures are prepared by simple spontaneous deposition of nano-sized Au particles onto nickel foam surface in an aqueous solution of AuCl3. Their morphology and catalytic performance for NaBH4 electrooxidation and H2O2 electroreduction in NaOH solution are investigated. Au particles with diameters smaller than 100nm are uniformly deposited on the whole surface of all skeletons of the nickel foam substrate. The onset potential for NaBH4 electrooxidation and H2O2 electroreduction is about −1.2V and −0.1V, respectively. A direct liquid feed alkaline NaBH4–H2O2 fuel cell is constructed using Au/Ni-foam electrode as both the anode and the cathode. The effects of the concentration of NaBH4 and H2O2 and operation temperature on the fuel cell performance are investigated. The fuel cell exhibits an open circuit voltage of about 1.07V and a peak power density of 75mWcm−2 at a current density of 150mAcm−2 and a cell voltage of 0.5V operating on 0.2moldm−3 NaBH4 and 0.5moldm−3 H2O2 at 40°C. [Copyright &y& Elsevier]

After normal alkali treatment process, the industrial Cr(VI) containing wastewater still contains a ppm level of Cr(VI) ions which should be further purified before discharging. In this study, the Cr(VI)-containing wastewater has been efficiently treated by the porous paper sludge-based activated carbon (ps AC) with an excellent specific surface area and rich oxygen functional groups. The batch experimental results showed that under acidic conditions, pH has little effect on the Cr(VI) removal. The kinetic and isotherms studies showed that the Elovich and Freundlich model could describe the adsorption process well and the maximum adsorption capacity of ps AC was 54.04 mg/g. The thermodynamic studies indicated that the reaction process was endothermic and spontaneous. Adsorption enthalpy was 17.37 kJ/mol, showing that the chemisorption process was a hydrogen bonding-controlled that has been also verified by some analytical techniques. Lastly, this study also provided an idea for reutilization of waster Cr(VI)-contained ps AC in furfural hydrogenation. Unlabelled Image • The effects of multiple factors on the performance of activated carbon • The highest Cr(VI) removal capacity of ps AC reached as high as 54.04 mg g−1. • Cr(VI) interacts with ps AC surface functional groups by hydrogen bonding. • Cr(VI)-contained ps AC was an excellent catalyst precursor. [ABSTRACT FROM AUTHOR]