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In the present study, Ru modified hierarchical zeolites xRu-MZSM were developed for cellulose fast pyrolysis. Comprehensive catalyst characterizations including XRD, XPS, N2 adsorption-desorption, Py-IR and so on, were performed to unveil the essential structural properties. The chemical modification and Ru decoration remarkably regulated the distribution of Bronsted/Lewis acid sites. The presence of RuOx species would supply abundant strong Lewis acid sites for participating catalytic cracking, dehydration, decarbonylation, decarboxylation, cyclization, aromatization, etc., in cooperation with Bronsted acid sites. In-situ generated active Ru0 centers during cellulose pyrolysis might facilitate the proceeding of deoxygenation, hydride transfer, and dehydrogenation. Among the as-prepared catalysts screened, 2Ru-MZSM was much more efficient in aromatics production from cellulose fast pyrolysis compared to parent ZSM, wherein the total aromatics yield achieved 16.8% at temperature of 650 °C and heating rate of 10 °C/ms with corresponding E value as low as 23.40 kJ/mol. Also, plausible reaction mechanism for xRu-MZSM involved cellulose fast pyrolysis was proposed in detail.

Magnetic separable biochar holds great promise for the treatment of Pb2+-contaminated wastewater. However, the absorption effect of unmodified magnetic biochar is poor. Considering this gap in knowledge, CeO2-doped magnetic coconut coir biochar (Ce-MCB) and magnetic coconut coir biochar (MCB) for Pb2+ absorption were prepared by the impregnation method, and the efficiency of Ce-MCB for Pb2+ absorption was evaluated in comparison with MCB. Conducting the absorption experiments, the study provided theoretical support for the exploration of the absorption mechanism. The quantitative analysis exposed that the enhanced absorption capacity of Ce-MCB was attributed to the increase in oxygen-containing functional groups and mineral precipitation. The Langmuir and Freundlich isotherm model showed that Ce-MCB is a suitable adsorbent for Pb2+. The absorption characteristics of Ce-MCB was fit well with the pseudo-second-order (PSO) and Langmuir models, which revealed that the absorption of Pb2+ in water was monolayer chemisorption with a maximum theoretical adsorption capacity of 140.83 mg·g−1. The adsorption capacity of Ce-MCB for Pb(II) was sustained above 70% after four cycles. In addition, the saturation magnetization intensity of Ce-MCB was 7.15 emu·g−1, which was sufficient to separate out from the solution. Overall, Ce-MCB has wide application prospects in terms of biomass resources recycling and environmental conservation.

In the present research, a series of metal oxides were employed to investigate the role of varied acid-base site on kinetics and mechanism for catalytic fast pyrolysis of cellulose using TG-MS and Py-GC/MS. The results showed that the modulation of acidity-to-basicity value via altering metal oxides constituents significantly affected the transformation pathway for cellulose pyrolysis. Higher acidity-to-basicity ratios accelerated the proceeding of deoxygenation process, wherein 39.4% aromatics and 34.7% aliphatic hydrocarbons were achieved using Al2O3 (acidity-to-basicity value of 1.38) at 750 °C with a catalyst/cellulose mass ratio of 15:1. In comparison, lowering acidity-to-basicity ratios mainly facilitated the ketonization and aldol condensation, therefore over 70% ketones was attained in the case of CaO catalysis. The kinetic studies further verified the promotional role of acid-base sites on cellulose pyrolysis with apparent activation energy as low as 33.72 kJ/mol, in comparison with that of cellulose pyrolysis without adding catalysts. From another aspect, the composite metal oxides with better porous structures contributed to deoxygenation conversion for the production of aromatics and aliphatic hydrocarbons. Moreover, plausible reaction pathway for cellulose pyrolysis over metal oxides was proposed. This work would provide a good reference for the realization of product regulation from cellulose pyrolysis via adjusting acid-base sites in metal oxides.

e-Caprolactone is traditionally produced through Baeyer-Villiger oxidation of cyclohexanone oxidized by peracids in industry, which inevitably results in large discard acid and environmental pollution. To this end, a green route to e-caprolactone was developed by coupling the direct generation of hydrogen peroxide from aerobic oxidation of benzhydrol catalyzed by NHPI and Baeyer-Villiger oxidation of cyclohexanone with the in situ hydrogen peroxide over Sn-Beta zeolites in one pot. Molecular oxygen was employed as the terminal oxidant, and the effects of several reaction factors were studied. Compared with one-step process, the one-pot two-step method noticeably improved the selectivity of e-caprolactone. When the amount of in situ hydrogen peroxide was 0.72 equivalent, the selectivity of e-caprolactone was obtained 94.8% with 39.2% conversion of cyclohexanone, and the efficiency of H2O2 was up to 51.5%. As compared to the commercial 30 wt% aqueous H2O2 added directly, in situ H2O2 dramatically improved the selectivity of e-caprolactone and had higher efficiency. Additionally, the catalyst could be easily separated from the reaction solution and reused several times without the remarkable loss of activity.

Lead ion (Pb2+) in wastewater cannot be biodegraded and destroyed. It can easily be enriched in living organisms, which causes serious harm to the environment and human health. Among the existing treatment technologies, adsorption is a green and efficient way to treat heavy metal contamination. Novel KMnO4-treated magnetic biochar (KFBC) was successfully synthesized by the addition of Fe(NO3)3 and KMnO4 treatment during carbonization following Pb2+ adsorption. SEM-EDS, XPS, and ICP-OES were used to evaluate the KFBC and magnetic biochar (FBC) on the surface morphology, surface chemistry characteristics, surface functional groups, and Pb2+ adsorption behavior. The effects of pH on the Pb2+ solution, initial concentration of Pb2+, adsorption time, and influencing ions on the adsorption amount of Pb2+ were examined, and the adsorption mechanisms of FBC and KFBC on Pb2+ were investigated. The results showed that pH had a strong influence on the adsorption of KFBC and the optimum adsorption pH was 5. The saturation adsorption capacity fitted by the model was 170.668 mg/g. The successful loading of manganese oxides and the enhanced oxygen functional groups, as evidenced by XPS and FTIR data, improved KFBC for heavy metal adsorption. Mineral precipitation, functional group complexation, and π-electron interactions were the primary adsorption processes.

Waste rice husk char supported Fe and Ni were synthesized to prepare the monometallic and bimetallic catalysts for removing the tar model compound benzene in a laboratory dual-stage reactor. The prepared catalysts were examined by microstructure and textural characterization to analyse catalytic performance and stability. The molar proportions of CO, H2, CO2 and CH4 in the generated gas and the influence of residence time (τ) and the steam-to-carbon ratio (S/C) on the catalytic reaction were investigated. The results show that the rice husk char-based catalysts showed excellent catalytic activity for syngas production and benzene conversion. Under optimized conditions, the benzene conversion can reach 95.2%, and the mol% of syngas in the generated gas is greater than 93.0%, of which 91.0% is H2. The experimental results show that the influence of residence time on catalytic performance is greater than that of the steam-to-carbon ratio, and that excessive τ or S/C values will have no more positive effect on the performance of the catalyst. The stable active sites on the catalyst surface can guarantee the catalytic activity in the reaction. Ultimately, rice husk char-based catalysts can be used to remove tar and produce syngas.

Quinolones are widely used in the pharmaceutical industry; however, the high residue of these antibiotics has caused serious water quality issues, and their effective removal is still a great challenge. In this work, bimetallic magnetic FexMny catalysts are prepared by a facile impregnation method and are efficient for photocatalytic removal of five typical quinolone pollutants without oxidant under simulated light irradiation. The fabricated bimetallic magnetic FexMny catalyst with the Fe3+/Mn2+ ratio of 1 : 1 exhibits a large surface area of 122.5 m2 g−1, highly porous structure, rich defects and a covalent metal environment. These fabricated semiconductor catalysts can degrade 98.3% of ciprofloxacin (CIP), 96.0% of ofloxacin (OFL), 91.0% of enrofloxacin (ENR), 92.2% of levofloxacin (LEV), and 93.5% of norfloxacin (NOR) in 30 min without using any oxidant. The magnetic FexMny catalysts can be simply recycled using a magnet and maintain high stability, avoiding complex recycling procedures. Even after five cycles, the degradation rate of CIP was still over 92.0%. The degradation performance is far superior to that of most previously reported candidates. The bimetallic FexMny catalyst improves the ability to capture sunlight, increases the interface charge transfer rate, and inhibits the recombination of photogenerated electron–hole pairs. In addition, the mechanism and the main intermediates in the photocatalytic degradation of CIP are explored by quenching experiments, electron paramagnetic resonance (EPR) and liquid chromatography-mass spectrometry (LC-MS) analysis. These noble-metal free magnetic FexMny catalysts provide a promising opportunity for advanced photocatalytic oxidation technology to treat wastewater.

The efficient utilization of renewable biogas has attracted ever-increasing interest in the past few decades. Ni–Ce1−xZrxO2 supported on monolithic SiC-F (named Ni–Ce1−xZrxO2/SiC-F) is developed and applied in biogas reforming. Monolithic Ni–Ce1−xZrxO2/SiC-F catalysts were comprehensively characterized by ICP-AES, XRD, SEM, HR-TEM, CO2-TPD, etc. The promotional roles of Ce1−xZrxO2 in coke elimination as well as CO2 activation were deeply analyzed via in situ CH4-TPSR/CO2-TPO and in situ H2-TPR/CO2-TPSR. Ni–Ce1−xZrxO2/SiC-F exhibits satisfactory catalytic activity and ability to inhibit sintering and coke-deposition due to (a) the homogeneous dispersion of Ni nanoparticles (NPs) and (b) the strong interaction between Ce1−xZrxO2 solid solutions and Ni NPs. At 900 °C and a weight hourly space velocity (WHSV) of 24 000 mL gcat−1 h−1, an excellent CH4/CO2 conversion of 90/92% was initially achieved over the Ni–Ce1−xZrxO2/SiC-F catalyst, followed by a slight decrease after 150 h, but remained basically stable for the next 250 h.

Pyrolytic char as a catalyst carrier has been widely used in tar removal. This paper aimed to develop a cost-effective and eco-friendly tar steam reforming approach by using waste peat char supported Ca catalysts in a laboratory dual-stage reactor. Tar model compound toluene was used in steam reforming experiment for facilitate fundamental research. The reaction temperature, residence time, steam-to-carbon ratio and the molar ratios of H2, CO, CO2 and CH4 in the generated gas were investigated. Experimental results show that the peat char supported Ca catalysts had good selectivity for H2, especially the catalyst which activated by KOH and CO2. The catalyst demonstrated better catalytic activity with a higher residence time (0.6 s–0.7 s) and S/C ratio (S/C > 2.5). Under the optimized conditions, the toluene conversion and the mol% of H2 can reached 94.4% and 68.5%, respectively. Meanwhile, the activity of the catalyst was proved by a variety of performance tests, and the deactivation and mechanism of catalysts were investigated. Finally, these cost-effective and green peat char-supported Ca catalysts could be used for tar removal.

The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway.

Efficient electrocatalyst at renewable, economic and for oxygen reduction reaction are particularly important for next-generation fuel cells and metal-air batteries, yet remains a great c...

In this contribution, biochar from municipal sludge was used as a novel matrix for the synthesis of a series of calcium-based heterogeneous catalysts toward biodiesel production. Their catalytic activity was investigated in terms of catalyst loading and calcination temperature during preparation, in addition to the transesterification parameters including the methanol/oil molar ratio, reaction time, and catalyst amount. The highest biodiesel yield up to 93.77% was achieved with the 30Ca/A-SBC-700, and it maintained as high as 84.9% even after 10 cycles of a consecutively alternating catalysis and regeneration process. It was revealed that the porous municipal sludge biochar and autologous SiO2 were accountable for the superior stability of the present catalyst. This work may provide a new path to value-added valorization of sludge waste and also a renewable and efficient catalyst for biodiesel production at a low cost.

Microbial fuel cells (MFCs) are widely explored for promising green and renewable energy generation; however, their strong reliance on noble metal-based catalysts causes high fabrication costs and thus limits their widespread applications. Herein, metal-free alternatives derived from naturally abundant, renewable pomelo peels are explored. Two kinds of pomelo peel-derived novel N-doped carbocatalysts are presented, i.e., biochar microspheres (BCMs) and their activated porous counterpart (a-BCMs). In comparison with BCMs, the thermal activation processing endowed a-BCMs with significantly enhanced porosity, an elevated N doping content (2.41 vs. 0.51 at%), a 5-fold increased specific surface area (314.3 vs. 62.8 m2 g−1), and a much improved electrical conductivity (0.13 vs. 0.006 S cm−1). This metal-free a-BCM catalyst is subsequently employed to construct an MFC cathode for the oxygen reduction reaction (ORR), and an impressive electrocatalytic activity is achieved in 0.1 mol L−1 phosphate-buffered saline (PBS) buffer. The maximum power density reaches as high as 907.2 mW m−2, comparable to that of the costly Pt/C counterpart (1022.9 mW m−2). The long-term durability of the a-BCM electrocatalyst is also demonstrated by continuous running for 90 days, even superior to that of Pt/C. The origin of this excellent electrocatalytic performance of a-BCMs is deeply analyzed and discussed. Furthermore, the 4e− reduction pathway is also unraveled for the efficient and durable carbocatalysis of the ORR over a-BCMs in MFCs.

A series of TiO2/biochar composite catalysts were prepared by the hydrolysis method for the degradation of methyl orange, where biochar was obtained from the pyrolysis of waste walnut shells. The catalysts were examined by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS), elemental analysis and ultra violet-visible diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activity results showed that the catalysts noted as CT0.1/1, CT0.2/2 and CT 0.5/1 exhibited higher catalytic activity than that of pure TiO2. Besides, catalyst CT0.2/1 exhibited the highest catalytic activity (the decolorization efficiency of 96.88% and the mineralization efficiency of 83.23% were obtained), attributed to the synergistic effect of biochar and TiO2, while CT1/1 possessed the lowest activity due to the shelter of light by the excess biochar. After 5 repeated use, the catalyst CT0.2/1 still exhibited rather high activity toward the degradation of MO, where the decolorization efficiency and mineralization efficiency of MO achieved 92.45% and 76.56%, and the loss of activity was negligible.

Although oxygen reduction reaction (ORR) plays a key role in the cathodic part of many emerging energy conversion devices, it has naturally suffered from sluggish kinetics and high overpotential. We here report the facile synthesis of Fe-N co-doped carbon with a hierarchical porosity and in-situ formed graphene from biomass tar using urea as the nitrogen dopant, and FeCl3 as the porogen, catalyst, and Fe dopant. This exhibited an ORR catalytic activity comparable to that of a Pt/C catalyst in relation to its onset potential, limited diffusion current, and stability under an alkaline condition. It was found that the excellent catalytic performance should have originated from its large specific surface area, abundant active centers, and long-term conductive network. This renewable non-noble-metal catalyst may serve as an appropriate alternative to conventional noble catalysts in ORR-based techniques, and will also encourage investigations on the use of biomass tar for advanced materials toward various ends. Keywords: Biomass tar, Graphene, Hierarchically porous carbon, Co-doping, Oxygen reduction reaction

In this study, the biochar which was obtained from peat was modified and served as the support for the preparation of cost-effective solid base catalysts for the transesterification reaction. The composition, structure and texture of prepared catalysts were examined by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), N2 adsorption/desorption, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and the Hammett indicator method. It was found that the surface area and pore volume of the peat biochar were increased significantly (from 80.25 m2/g and 105.36 mm3/g to 230.86 m2/g and 296.23 mm3/g, respectively) by chemical activation treatment with KOH. The best performance is observed for the resulting 30Ca/APB-700 catalyst (30% CaO loading and 700 °C calcination temperature), and over biodiesel yield of 93.4% was achieved at catalyst amount of 5 wt.%, methanol/oil molar ratio of 8:1 and reaction time of 150 min. Besides, after reused for 10 cycles, the catalytic efficiency had a slight deactivation in biodiesel production (above 81.6% of yield obtained). The high stability of catalyst was mainly attributed to the formation of Ca O Si bond on the catalyst surface.

In the present study, catalytic fast pyrolysis of waste mixed cloth in an ex-situ method using hierarchical HZSM and commercial CaO was investigated. Pyrolysis of waste mixed cloth in a temperature range of 450 °C to 750 °C mainly allowed for the formation of levoglucosan without any catalysts. The utilization of HZSM with Bronsted/Lewis acid sites on micro- and mesoporous structures significantly contributed to monocyclic/dicyclic chemicals production, mainly referring to monoaromatics and naphthalene-based derivatives, especially in the case of high heating rates and catalyst usages. Furthermore, CaO revealed strong deoxygenation performance for the transformation of waste mixed cloth into low oxygen-containing chemicals, such as ketones, aliphatic hydrocarbons and aromatics. The present research thus highlights a feasible route for the catalytic upgrading of waste mixed cloth into some kinds of value-added chemicals.

Biomass-derived chemical looping gasification (BCLG) is a novel technology for lignocellulose energy applications. Ca-Fe oxygen carriers have been proven to be a potential material for efficient lignocellulose conversion and hydrogen-enriched syngas production in process studies. In this study, Thermogravimetry-mass spectrometry (TG-MS), pyrolysis chromatography-mass spectrometry (Py-GC-MS) and fixed-bed experiments were conducted, and the cellulose BCLG product was analyzed to explore the mechanism of reaction between Ca-Fe OCs and biomass char or volatiles. The mechanism of the synergistic effect of Ca-Fe was analyzed to explain the characteristics of the OCs. The results showed the Ca-based materials act as catalysts to promote the decomposition of cellulose monomers at primary reaction and char at secondary reaction. And also promote the reforming and oxidation of volatiles by chemisorption. Ca participates in the construction of inert substances, such as Ca 2 Fe 2 O 5 , to avoid the deep oxidation of CO and H 2 . Fe-based material supplies oxygen and promotes the reforming of volatile. Compared with Fe 2 O 3 and CaO/Fe 2 O 3 , CaFe 2 O 4 showed a better performance on carbon conversion and H 2 production below 850 °C.

Hierarchically three-dimensional (3D) micro-nanostructures have promising applications in multifarious fields. Herein, we report a general strategy, that is, in situ catalysis process, for fabrication of nitrogen-doped carbon nanotube (NCNT) arrays on one-dimensional (1D) nitrogen-doped carbon (NC) skeletons. The NCNT arrays branch out from the 1D NC surfaces, resulting in the formation of hierarchically 3D micro-nanostructures. The strategy is involved in the pyrolysis of M-precursor (M = Fe, Co, and Ni) nanowires with the assistance of dicyandiamide. During the synthesis process, the metal components in the precursors serve as catalysts for growing NCNTs, while dicyandiamide provides carbon and nitrogen sources. With the ongoing reaction, the NCNTs were catalytically grown and branched out from 1D NC skeletons. Through the strategy, three kinds of hierarchically 3D structures with encapsulated Fe/Fe

Biomass-derived chemical looping gasification (BCLG) is a novel technology for lignocellulose energy applications. Ca-Fe oxygen carriers have been proven to be a potential material for efficient lignocellulose conversion and hydrogen-enriched syngas production in process studies. In this study, Thermogravimetry-mass spectrometry (TG-MS), pyrolysis chromatography-mass spectrometry (Py-GC-MS) and fixed-bed experiments were conducted, and the cellulose BCLG product was analyzed to explore the mechanism of reaction between Ca-Fe OCs and biomass char or volatiles. The mechanism of the synergistic effect of Ca-Fe was analyzed to explain the characteristics of the OCs. The results suggest the Ca-based materials act as catalysts to promote the decomposition of cellulose monomers at primary reaction and char at secondary reaction, and also promote the reforming and oxidation of volatiles by chemisorption. Ca participates in the construction of inert substances, such as Ca2Fe2O5, to avoid the deep oxidation of CO and H2. Fe-based material supplies oxygen and promotes the reforming of volatile. Compared with Fe2O3 and CaO/Fe2O3, CaFe2O4 shows a better performance on carbon conversion and H2 production below 850 °C.

An investigation of aerobic oxidation of 2-methoxy-4-methylphenol to vanillin catalyzed by a number of cobalt salts, complexes, oxides, and hydroxides in alkaline solutions is reported. A good yield of vanillin (90%) was obtained when CoCl2 was used as the catalyst, while a poor yield (6%) was obtained with Co3O4. Unexpectedly, however, the Co3O4 catalytic activity was restored after heating in an alcoholic solution of NaOH for 24 h, producing a good yield of vanillin (85%). The recovered catalytic activity of Co3O4 indicated a conversion of inactivated heterogeneous particles to activated particles. In addition, precipitates were generated when “homogeneous” CoCl2 was employed as a catalyst, making us wonder about the true nature of the catalyst in this reaction. A series of experiments are described, including kinetic studies, filtration tests, centrifugation tests, dynamic light scattering, transmission electron microscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction, for the investi...

Ionic liquids-based microwave-assisted hydrolysis was successfully applied for hydrolysis of puerarin and daidzein derivatives from Radix Puerariae Lobatae extract. The ionic liquids with different cations and anions have been investigated, and [Omim]HSO4 was selected as catalyst. In addition, the hydrolysis parameters, including catalyst quantity, ionic liquids concentration, microwave power and microwave time, were optimized by Response Surface Methodology. The optimal conditions were as follows: 0.82 mol/L [Omim]HSO4; catalyst quantity, 1.42 mL; microwave time, 7 min; microwave power, 400 W. Under those condition the average hydrolysis efficiency of puerarin and daidzein derivatives was 57.93 ± 3.08%. Compared with the traditional acidic catalysts, the [Omim]HSO4 exhibited higher efficiency, which demonstrates that ionic liquids-based microwave-assisted hydrolysis was a rapid, efficient, and simple hydrolysis technique.

The paper aims to investigate an effective method of catalytic reforming of toluene using peat char-supported Ni metal to achieve clean gas production. Utilizing KOH or CO2 activation to increases the surface area and pore volume of peat char during catalyst preparation. The chemical and structural properties of catalysts is explained based on SEM, EDS, XRD, BET method. Meanwhile, the influence of reaction temperature, residence times (τ), steam-to‑carbon ratios (S/C) in catalytic reaction and the molar ratio of CO, CO2, H2, CH4 in clean gas were investigated. The results indicated that SiO2 structure plays a significant role in nickel-based peat char catalyst, and the catalyst exhibited high catalytic performance. Conversion efficiencies of toluene can reach about 95.3% using Ni/APC catalyst at residence time of 0.5 s, steam-to‑carbon ratio of 3:1, temperature of 850 °C. The catalyst also exerted a positive effect on the syngas (CO + H2) production with the maximum molar ratio reaching up to 94.7 mol% under the optimized conditions. The high catalytic activity was mainly attributed to the structure of AlNi2Si and NiSi on the catalyst surface. Therefore, the cost-effective peat char-supported Ni catalysts could be used for aromatic tar conversion.

A homogeneous catalyst system FeCl3/DMSO was developed to catalyze α-substituted cyclohexanone to corresponding 6-oxohexanoic acid, an important intermediate involved during the synthesis of (+)-biotin. A highly efficient oxidation with 95.3 % of conversion and 88.0 % of selectivity was achieved using oxygen as the oxidant, which shows great advantage over the traditional peroxide method from industrial aspects. The detailed reaction process was evaluated to determine the parallel reactions scheme consisted by two oxidative reactions and one chlorination reaction. The [Fe(DMSO)4Cl2]Cl complex detected by UV–vis and FT-IR spectrometer was proposed as the active component during the catalytic process. The control experiments, capture of important intermediates, and kinetic study were performed, which showed the oxidation proceeded via the combination of ionic and radical pathway. The FeCl3/DMSO can be recycled with minor yield loss.

The development of highly efficient and inexpensive carbon-based catalysts for the production of hydrogen from water electrolysis is a considerable challenge in the field of sustainable energy transformation. Herein, an in situ N-, P- and Ca-codoped biochar was successfully fabricated from animal bone by thermal treatment at 800 °C. This in situ N-, P- and Ca-codoped catalyst exhibits high atomic contents with synergistic effects of N, P and Ca, a large electrochemically active surface area, a low charge-transfer resistance, high conductivity, and a large specific area. These characteristics lead to an outstanding hydrogen evolution reaction (HER) activity and good stability in a H2SO4 acidic solution, with an onset potential of 80±3 mV, an overpotential of 162±3 mV at a current density of 10 mA/cm2, a Tafel slope of 80 mV/dec, and an exchange current density of 52.5 µA/cm2, which are comparable to or even better than those of synthetic heteroatom-doped or transition metal-doped carbon-based catalysts. These findings demonstrate that animal bone is a useful material for the preparation of N-, P- and Ca-codoped carbon materials as effective electrocatalysts for the HER.

In this manuscript, the biochar obtained from waste pig meat and bone meal was modified and served as the support for the preparation of cost-effective solid base catalysts for the transesterification reaction. The composition, structure and texture of prepared catalysts were examined by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), N 2 adsorption/desorption, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and the Hammett indicator method. In addition, the effects of catalyst preparation conditions, reaction conditions and the catalyst reusability were studied in detail. Meanwhile, the mechanism of catalyst was also discussed. It was found that the surface area and pore volume of the biochar were increased significantly (from 142.644 m 2 /g and 190.63 mm 3 /g to 430.517 m 2 /g and 486.56 mm 3 /g, respectively) by chemical activation treatment with KOH. The best performance is observed for the resulting 30K/AMB-550 catalyst, and over biodiesel yield of 98.2% was achieved at catalyst amount of 5 wt%, methanol/oil molar ratio of 7:1 and reaction time of 150 min. Besides, after reused for 10 cycles, only a slight deactivation was found (above 84% of yield obtained) due to K + ions leached into reaction media.

Heteroatom-doped lamellar-structured carbon with a high surface area synthesized from alfalfa leaves is utilized as a cathode catalyst in this study to improve the power output of microbial fuel cells (MFCs). Different chemical activation agents are used to treat alfalfa leaf-derived carbon (ALC). It is found that chemical activation agents substantially affect the catalytic activities of the alfalfa leaf-derived carbon materials in the power output of MFCs and the oxygen reduction reaction (ORR). ALC materials activated by KOH (ALC-K) exhibit the best electrochemical activity compared with those of materials activated by FeCl3 (ALC-Fe) or ZnCl2 (ALC-Zn). A high limiting current density and excellent long-term stability can be seen with ALC-K as the cathode catalyst, which gives superior results to those of Pt/C. Moreover, a maximum power density of approximately 1328.9 mW/m2 is obtained from an MFC equipped with an ALC-K cathode, offering performance characteristics comparable to those of a Pt/C cathode ...

In the present study, the peat, as solid waste, was utilized as the support to prepare carbon solid base catalyst for biodiesel production from palm oil. The chemical and structural properties of catalysts were examined by thermogravimetric analysis (TGA), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), N2 adsorption/desorption and the Hammett indicator method. The results indicated that 30K/PB-600 catalyst exhibited the highest catalytic activity (the maximum biodiesel yield of 98.6% was acquired) owing to its highest total basicity. Besides, the stability of the catalyst during reaction was also demonstrated. After 9 repeated use, the catalyst could still possess a rather high catalytic activity (biodiesel yield of 81%). The little deactivation of catalyst was mainly owing to K+ ions leached into reaction media. Therefore, biochar derived from peat could prove to be an appropriate material for catalyst synthesis.

A series of stable natural diatomite-supported CaO catalysts were synthesized for biodiesel production. All materials have been thoroughly characterized by Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS), Fourier transform-infrared spectroscopy (FTIR), IR-Raman, X-ray diffraction (XRD), N 2 adsorption/desorption, and Hammett indicator. The results indicated that 30Ca/Di_800 catalyst exhibited the highest catalytic activity (a biodiesel yield of 92.4% was acquired) owing to its highest total basicity. Meanwhile, the superior stability of the catalyst during reaction was also demonstrated. The catalyst can be recycled 10 times without significant loss of catalytic efficiency. Therefore, natural diatomite not only can be successfully used as the support for the synthesis of catalyst but also can strongly interact with CaO to form the stable Ca O Si bond. Furthermore, the as-synthesized catalyst also exhibited good better water-tolerant ability. The Ca O Si bond existed on the catalyst surface considered to be a main factor for its high stability and water-tolerance.

A new vision of using carbon dioxide (CO2) catalytic processing of oleic acid into C8–C15 alkanes over a nano-nickel/zeolite catalyst is reported in this paper. The inherent and essential reasons which make this achievable are clearly resolved by using totally new catalytic reaction pathways of oleic acid transformation in a CO2 atmosphere. The yield of C8–C15 ingredients reaches 73.10 mol% in a CO2 atmosphere, which is much higher than the 49.67 mol% yield obtained in a hydrogen (H2) atmosphere. In the absence of an external H2 source, products which are similar to aviation fuel are generated where aromatization of propene (C3H6) oxidative dehydrogenation (ODH) involving CO2 and propane (C3H8) and hydrogen transfer reactions are found to account for hydrogen liberation in oleic acid and achieve its re-arrangement in the final alkane products. The reaction pathway in the CO2 atmosphere is significantly different from that in the H2 atmosphere, as shown by the presence of 8-heptadecene, γ-stearolactone, and 3-heptadecene as reaction intermediates, as well as a CO formation pathway. Because of the highly dispersed Ni metal center on the zeolite support, H2 spillover is observed in the H2 atmosphere, which inhibits the production of short-chain alkanes and reveals the inherent disadvantage of using H2. The CO2 processing of oleic acid described in this paper will significantly contribute to future CO2 utilization chemistry and provide an economical and promising approach for the production of sustainable alkane products which are similar to aviation fuel.

Cathode catalysts with excellent efficiencies, low costs and long-term durability in microbial fuel cell (MFC) applications have attracted considerable attention. Herein, hierarchically structured carbons with honeycomb-like interconnected macro-mesoporous frameworks and N, P, and Fe heteroatom doping have been successfully prepared through direct pyrolysis from livestock sewage sludge. In neutral media, the as-prepared activated livestock sewage sludge carbon (LSC-A) catalyst displayed great electrocatalytic activity for the oxygen reduction reaction (ORR), and a maximum power density of 1273 ± 3 mW/m 2 was obtained when this catalyst applied in MFCs, which is comparable to that of commercial Pt/C (1294 ± 2 mW/m 2 ). Furthermore, after 90 days of operation, the voltage output of the MFC with the LSC-A cathode decreased only 10.2%, which is considerably lower than the 28.4% decrease of the Pt/C cathode, indicating that LSC-A possesses a greater long-term stability than the Pt/C cathode. This study demonstrated that the N, P, Fe-doped honeycomb-like hierarchically structured carbon derived from livestock sewage sludge is a cost-efficient and promising cathode catalyst for scaling up MFCs.

A series of boron doped magnetic zirconium catalysts were developed for the selective transfer hydrogenation of biomass-derived furfural (FFR) into furfuryl alcohol (FA) using 2-propanol as hydrogen source and solvent. Full characterizations with XRD, SEM, TG, Py-IR, NH3-TPD, and CO2-TPD techniques were undertaken to uncover structural properties of magnetic catalysts. Boron doped magnetic zirconium catalysts endowing with adjustable acid-base sites exhibited excellent performance as well as good regenerability in the transfer hydrogenation of FFR, where almost 100% FA yield was achieved in the presence of 2-propanol and the catalyst still sustained good activity after being used five times. Suitable acidity/basicity ratio of 3.8 ~ 4.0 apparently benefited the selective production of FA. Gratifyingly, the activation energy for FA formation over Zr1B3FeO was as low as 48.3 kJ/mol. In addition, plausible reaction mechanism involving two H-transfer paths for transfer hydrogenation of FFR into FA under the catalysis of active Zr/B species was proposed.

With quite limited use, biomass tar has been a long-standing issue that strongly impaired the cost-efficiency of biomass gasification. Here, a facile activation-annealing route for upcycling biomass tar into graphene nanohybrids with developed porosity and enriched pyridinic nitrogen was reported, whilst the metal-free product revealed with superior catalytic activities to the benchmark Pt/C and RuO2 catalysts toward oxygen reduction reaction (ORR) and evolution reaction (OER). By associating the dual functionalities with products’ physiochemical properties, it was unveiled that those pyridinic-N and defects were accounted for the promoted oxygen reduction and evolution, respectively. Together with reinforced electric conductivity and hierarchical porosity and enlarged interface via ammonia annealing, the heterogeneously structured carbon catalyst finally endowed an assembled primary Zn-air battery with maximum energy density of 121 mW/cm−2, in addition to robust stability against long-term running. This work highlights the great potential of biomass tar for advanced carbon materials, and therefore a novel strategy to address the tar-related challenges faced by gasification technologies.

The synthesis of heterogeneous catalysts from waste materials has become increasingly popular over the past two decades. Among them, Ca-based catalysts have widely been tested in the transesterification reaction because of their relatively high catalytic activity and the large amount of feedstock (calcium rich waste materials) available. Those Ca-based catalysts can be simply prepared via the high temperature calcination and using these waste materials to generate the catalyst in addition to the target product makes the system more cost effective and environmentally friendly. This review presents general information related to the recent progress in the development of various Ca-based catalysts derived from waste materials for biodiesel production. The materials described include eggshells, mollusk shells, bones, large-scale industrial wastes and so on. Meanwhile, based on this collection of data and information, the catalytic activity mechanism, future challenges and prospects of renewable resources derived catalysts are also discussed. (C) 2016 Elsevier Ltd. All rights reserved.

The mechanism for aerobic oxidation of methylaromatic compounds using Co(CH3COO)2–Mn(CH3COO)2–KBr was further studied. The experimental results suggested that the intermediates (aromatic alcohols) are unexpectedly inert to direct oxidation via Co–Mn–Br catalysts under moderate conditions. In addition, it is found that both aromatic and aliphatic alcohols can inhibit the oxidation of the substrates and other intermediates (aromatic esters, aromatic aldehydes). UV–vis spectra indicated that oxidation from Co(II) to Co(III) would be interrupted in the presence of a given amount of alcohol. A plausible mechanism was also proposed. The intermediates analyzed by LC–MS and control experiments showed that aromatic alcohols prefer to undergo esterification rather than being directly oxidized as described in previous studies, and aromatic acetates are subsequently oxidized to corresponding aldehydes. According to the new mechanism, a strategy of highly selectively synthesizing aromatic alcohols and aldehydes from corresponding methylaromatic compounds was designed. The selectivities of aromatic alcohols and aldehydes could also be tuned by the added amount of CH3COOK.

Biochar, produced by the thermal decomposition of various biomass sources, is applied in different fields of research due to its distinctive properties. With the recent explosion of methods of a large-scale synthesis of biochar, the number of literatures relevant to biochar and biochar based materials has increased exponentially. This review exclusively focuses on the current development of biochar based functional catalysts, and provides critical emphasis on the different applications in various reactions, including (trans)esterification, catalytic reforming/cracking, gasification/pyrolysis, hydrolysis, electrochemical reactions, photocatalytic and persulfate/peroxymonosulfate oxidation, etc. Thus, in this review, we firstly present a brief description of the design and synthesis of the biochar based catalyst, and then summary the applications of these biochar based catalysts based upon different reactions. Finally, the current advances and the future perspectives of the biochar catalysts will be presented. Hopefully, this review will offer a perspective and guidelines for the future research and development of biochar based catalysts.

Pyrolytic char is widely used for tar removal due to its cost-effective and eco-friendly. In this work, the waste municipal sludge is selected to produce the composite catalyst with transition metal Fe/Ni, and the as-synthesized catalyst was used in the catalytic cracking of the tar model compound toluene by a laboratory-scale plant. The toluene conversion and the molar ratios of CO, H2, CO2, CH4 and C2H4 in the generated gas were investigated. Results show that municipal sludge char-based catalysts are more likely to produce H2-rich syngas (the molar ratio of syngas > 75%), and the molar ratio of H2 can reach 73.3% under optimal conditions. The Fe-Ni bimetallic catalyst combines the advantages of different metal elements to make the catalyst performance more stable. Meanwhile, the effects of residence time (τ) and steam-to-carbon ratio (S/C) on the conversion rate were studied. As a result, the excessive residence time or steam-to-carbon ratio will have no more positive effect on the performance of the catalyst. Ultimately, the catalyst life test of 8 h was carried out, the results showed that cost-effective and green waste municipal sludge char-supported Fe/Ni catalysts in this work could be used for removal of the tar heavy component toluene.

The demand for V2O5-WO3/TiO2 catalysts is growing as many countries impose increasingly stricter limits on nitrogen oxide emissions. Unfortunately, after service, the spent V2O5-WO3/TiO2 catalyst is continuously and considerably discarded. The cost of the catalyst accounts for approximately 30–50% of the total investment in the denitration system. Additionally, the spent catalyst contains significant amounts of valuable metals and some heavy metals. Thus, the regeneration to form a new catalyst or recovery of valuable metals from the spent V2O5-WO3/TiO2 catalyst has gained widespread attention in recent years, not only for meeting the growing demand for corresponding critical metals/catalysts but also reducing the potential ecological and environmental hazards caused by inappropriate disposal. In this article, a systematic review of the literature was conducted to examine recently developed processes and technologies for recycling the spent V2O5-WO3/TiO2 catalyst to recover either new catalysts or valuable metals. Moreover, the challenges associated with process optimization for the regeneration to form a new catalyst and the recovery of valuable metals were analyzed. The aim of this article is to provide a guideline on how effective processes and techniques for the spent V2O5-WO3/TiO2 catalyst recycling can be developed and to motivate further studies in this theme for industrial-scale realization.

One set of biochar-coupled Ag and TiO2 composites were successfully fabricated by mixing, calcination, and photodeposition method to remove methyl orange (MO). It was found that all catalysts modified with Ag showed better photocatalytic degradation performance (the highest decolorization efficiency and mineralization efficiency were 97.48% and 85.38%, respectively) than single TiO2 because of the synergy of Ag, TiO2 and biochar. Characterization results indicated that Ag as well as TiO2 acted as electron donor and biochar acted as electron acceptor, which could effectively promote the separation of photogenerated electron hole pairs. In addition, the catalyst exhibited high stability up to 5 cycles and the loss of activity was negligible. And the catalytic degradation process was consistent with the pseudo-first-order kinetic (PFOK) model with the degradation rate constant of 6.29 × 10−2 min−1.

The pyrolysis char from waste peat with impregnated metal (Fe/Ni/Ca) were investigated for catalytic reforming of toluene in a laboratory dual-stage reactor. The prepared catalysts were examined in microstructure and textural characterization to analyze catalytic performance and stability. The results indicated that under the optimized conditions, the toluene conversions are greater than 92.7% for three types of peat char-supported catalysts, and the maximum molar ratio of syngas (CO + H2) can reach up to 94.7% using Ni/peat char catalyst. The promising results demonstrated that the H2 and CO are favored for Fe/peat char and Ni/peat char catalysts while the H2 and CH4 are favored for Ca/peat char catalyst. After 320 min of experiment, the mol% of syngas decreased by less than 30% for three types of peat char catalysts. Significantly, peat char (C-SiO2) as a carrier can enhance the performance of catalyst through interaction with the metal, and it can be used as an adsorption carrier to absorb unreacted toluene. Such peat char-supported catalysts are thus promising for tar conversion and useful syngas production.

To avoid the use of peracids oxidant or highly concentrated hydrogen peroxide which is potentially hazardous and explosive, herein, a new route to e-caprolactone was developed in which molecule oxygen was employed as the terminal oxidant. The commercial available N-hydroxyphthalimide and ammonium cerium nitrate were used as the key catalysts for the increased yield of e-caprolactone. For instance, the selectivity of e-caprolactone was obtained 92 % with 85 % conversion of cyclohexanone which was comparable to the strategies using highly concentrated hydrogen peroxide. The sacrificed alcohols were transformed into corresponding ketones which were also valuable chemicals. Furthermore, the efficiency of the alcohols was achieved to unprecedented 52 %. The Baeyer-Villiger oxidation of various other cycloalkanones was also examined. The substituent group effect on the efficiency of sacrificed alcohols was investigated in which weak electron-donating substituent induced nearly quantitative yield of e-caprolactone. The reaction mechanism was studied with the help of electron paramagnetic resonance which indicated the existence of a radical pathway.

The pyrolysis char derived from solid waste peat was used in the removal of biomass tar. A laboratory dual-stage reactor was designed to obtain a cost-effective and eco-friendly tar removal approach using peat pyrolysis char-based catalyst. Rich pore structure of pyrolysis char can enhance the adsorption and removal performance of tar, the KOH and CO2 activation method were used to increase the pore structure of pyrolysis char. Toluene was chosen as the model compound of biomass tar for basic research. The effects of pyrolysis char and transition metal Fe on toluene removal were studied. The investigated reforming parameters were reaction temperature (700–900 °C), residence time (0.3–0.8 s) and steam-to-carbon ratio (1.5:1–4:1). The results indicated that the peat pyrolysis char-based Fe catalysts showed excellent catalytic performance (toluene conversion >89%) and gas selectivity, especially the catalyst that activated by CO2 had the best selectivity for syngas (88.1 mol%), and the waste peat catalyst was compared with other waste pyrolysis char-based catalysts. Textural characterization showed that the excellent catalytic activity and stability of the catalysts are due to the presence of FeC and FeSiO3 structures. Such the peat pyrolysis char can as a carrier be used to remove tar and produce high content syngas in pyrolysis process.

A series of magnetic zirconium nanoparticles with varied Zr/Fe molar ratios were synthesized and developed as acid−base bifunctional catalysts in the catalytic transfer hydrogenation (CTH) of biomass-derived furfural (FFR) and levulinic acid (LA) using 2-propanol as both hydrogen donor and solvent. Zirconium constituents coated on nano-sized Fe3O4 endowed the catalysts with abundant acid−base sites, moderate surface areas (94.0‒187.6 m2/g) and pore sizes (3.42–9.51 nm), thus giving nearly 100 % yields of furfuryl alcohol (FA) and γ-valerolactone (GVL) after 2 h of reaction. Particularly, competitive activation energy (Ea) for the CTH of FFR into FA over Zr1Fe1-300 was as low as 50.9 kJ/mol. Moreover, the easily separable nanocatalyst Zr1Fe1-150 was also applicable to CTH of various alkyl levulinates into GVL in high efficiency and could be reused for multiple cycles without obvious loss of its catalytic performance in the transfer hydrogenation of LA.