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NiCo-layered double hydroxide (NiCo-LDH) catalysts, which indicate a profound prospect of oxygen evolution reaction (OER) under alkaline conditions, are facing great challenges in terms of low electrical conductivity, restricted by poor conductivity, limited electrochemical reaction sites, and low-density of edge sites. The authors developed a simple and convenient in-situ one-pot self-assembly method. The Ce-doped defective NiCo-LDH hexagonal nanosheets and nitrogen-doped graphene fabricated the NiCoCe-LDH/RNF electrocatalyst on the nickel foam (NF) substrate, which demonstrated excellent OER activity under alkaline conditions, only needed 299 mV overvoltage to achieve 50 mA cm−2 current intensity, could last for 6 hours at 20 mA cm−2. The highly active OER benefited from the structural advantages of the novelty three-dimensional array structure. The novel geometric structure of tremella-shaped nanoflower integrated with curved nanosheets and curled edges loaded on NF provides more electrochemical reaction sites for intermediate coordination. The nitrogen-doped reduced graphene oxide accommodated better interaction between active materials and charge carriers, enhancing the conductivity and electron transfer performance of nanostructures. The effective synergistic between the heterostructures promoted the excellent OER electrocatalytic activity of NiFeCe-LDH/RNF nanocomposites. DFT calculations at the atomic level of pristine and Ce-doped NiCo-LDH exhibited that Ce-doping can reduce the Gibbs free energy of the potential-determining step and improve the catalytic activity of OER. This work has broadened the horizons for developing simple and highly available OER electrocatalysts. [Display omitted] • Ce doping and conductive composite enabled flexible active site engineering of LDH. • A novel tremella-shaped nanoflower structure was synthesized by in-situ self-assembly. • Effective synergy between heterostructures for efficient electrocatalytic oxygen evolution. [ABSTRACT FROM AUTHOR]

• Catalytic fast co-pyrolysis of RH and WGPFs over hierarchical catalyst via Py-GC/MS. • We designed a hierarchical HZSM-5/MCM-41 catalyst for catalytic fast pyrolysis. • Co-pyrolysis of RH and WGPFs leads to a total hydrocarbon yield of 71.1 wt%. • Optimum temperature and ratio of RH to WGPFs are 600 °C and 1/1.5, respectively. Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk over a hierarchical HZSM-5/MCM-41 catalyst was performed in an analytical Py-GC/MS. We evaluated the effect of pyrolysis temperature and the ratio of rice husk to waste greenhouse plastic films on the total peak area of condensable organic products and CO 2. In order to evaluate synergy possibilities among the two feedstocks, we performed non-catalytic pyrolysis and catalytic fast pyrolysis of rice husk and waste greenhouse plastic films separately. In addition, we report results for the catalytic fast co-pyrolysis of the mixture rice husk and waste greenhouse plastic films. The maximum relative content of hydrocarbons from catalytic fast co-pyrolysis of rice husk and waste greenhouse plastic films is obtained at 600 °C. When the mass ratio of rice husk to waste greenhouse plastic films is 1:1.5, the relative content of hydrocarbons reaches a maximum (71.1%). The hierarchical micro-mesoporous composite molecular sieve used in this work has outstanding catalytic activity and increases the relative content of hydrocarbons. [ABSTRACT FROM AUTHOR]

[Display omitted] • A trimetallic metal–organic framework N-doped nanosheet was synthesized as an electrocatalyst. • N-doping and trimetallic synergistic induce strong electron interaction and endow better intrinsic activity. • The electrode can stably deliver 10 mA cm−2 at 285 mV and with Tafel slopes of 72 mV dec-1 for OER. The serious concern about energy shortage and environmental pollution requires the development of next-generation energy storage and conversion equipment. People have made tremendous efforts in developing alternative electrode materials (like metal oxides, hydroxides, or their compound materials) for water electrolysis. Among them, polymetallic organic framework nanostructures have attracted much attention. Metal-organic frameworks (MOFs) have undergone a topological transformation and surface reconstruction, and the multi-metal coupling effect could significantly improve the performance of oxygen evolution reaction (OER), providing another way to obtain effective catalysts. In this study, a highly active two-dimensional (2D) MoCoFe hybrid nanosheets derived from MOFs (MoCoFe@NC) was prepared as an electrocatalyst for OER. Given the synergistic effect between 2D nanosheet structure and polymetallic electronic modification, it provides highly dispersed and accessible active sites for electrochemical reactions. At the same time, nitrogen doping and the formation of metal sulfide hybrid products on the carbon substrate improve the conductivity, showing the potential of bifunctional electrocatalysts. In alkaline electrolytes, the electrocatalyst reveals an initial potential of 1.45 V and only requires an overpotential of 285 mV to reach a current density of 10 mA cm−2 and has good endurance. It still exhibits excellent activity after continuous operation for 20,000 s. These findings not only contribute theoretical support to the correlation between polymetallic coordination structure evolution and OER catalytic activity in compound materials but also offer prospects for the development of hybrid electrocatalysts. [ABSTRACT FROM AUTHOR]

The high concentration of oxygenated compounds in pyrolytic products prohibits the conversion of hemicellulose to important biofuels and chemicals via fast pyrolysis. Herein a dual-catalyst bed of CaO and HZSM-5 was developed to convert acids in the pyrolytic products of xylan to valuable hydrocarbons. Meanwhile, LLDPE was co-pyrolyzed with xylan to supplement hydrogen during the catalysis of HZSM-5. The results showed that CaO could effectively transform acids into ketones. A minimum yield of acids (2.74%) and a maximum yield of ketones (42.93%) were obtained at a catalyst to feedstock ratio of 2:1. The dual-catalyst bed dramatically increased the yield of aromatics. Moreover, hydrogen-rich fragments derived from LLDPE promoted the Diels-Alder reactions of furans and participated in the hydrocarbon pool reactions of non-furanic compounds. As a result, a higher yield of hydrocarbons was achieved. This study provides a fundamental for recovering energy and chemicals from pyrolysis of hemicellulose. [ABSTRACT FROM AUTHOR]

In order to enhance aromatic hydrocarbon production, catalytic fast co-pyrolysis (co-CFP) of corn stover and fusel alcohol is conducted with ZSM-5 catalyst in a fluidized bed reactor. Effects of co-CFP temperature, catalyst loading and mass ratio of fusel alcohol to biomass on aromatic hydrocarbon yields are investigated and the experimental results show that bio-derived aromatic hydrocarbons can be formed through Diels-Alder cycloaddition and catalyst-induced hydrocarbon pool. It is found that co-CFP temperature of 550 °C results in the maximum aromatic hydrocarbon yield and the carbon and hydrogen yields of individual and total aromatic hydrocarbons increase dramatically with an elevated catalyst loading amount. Additionally, an apparent synergy between biomass and fusel alcohol is observed during co-CFP. With the consideration of aromatic hydrocarbon yields in bio-oil, the mass ratio of fusel alcohol to biomass of 1:1 in the blends is the best option. Moreover, isotopic labeling technique is utilized to unearth the origin of carbon and hydrogen in aromatic hydrocarbons, and the results demonstrate that carbon and hydrogen atoms from both feedstocks can coexist in the individual aromatic hydrocarbon and make up the targeted products during co-CFP of the blends. [ABSTRACT FROM AUTHOR]

An integrated modified HZSM-5 was prepared by sodium hydroxide leaching and followed by hydrothermal process in series, and the co-modified zeolites were then used to conduct the catalytic fast pyrolysis of waste cooking oil to investigate whether an enhanced production of aromatics could be obtained. X-ray diffraction, N 2 adsorption–desorption, TEM and NH 3 -TPD were utilized to characterize the modified zeolites. Experimental results indicated that the crystal structure of HZSM-5 was damaged as alkali treatment time was beyond 4 h, and a micro-mesopore hierarchical system was created inside the zeolites. Simultaneously, the strong acid sites decreased with the increment of modification time, while the weak acid sites performed an opposite inclination. The relative yields of aromatics and olefins presented deviation when alkali treatment time exceeded the specific limitation, and a moderate alkali treatment time of 4 h was beneficial for promoting the yield of aromatics. [ABSTRACT FROM AUTHOR]

The properties and characteristics of metal oxide and sulfate catalysts with different active elements for selective catalytic reduction of NO with NH3were investigated. Cerium-based oxide catalyst showed the widest temperature window for NOxremoval and manganese-based oxide catalyst exhibited the best catalytic performance at low temperature. For all the catalysts, the SCR activities at low temperature were directly related with the redox abilities of catalysts. The existence of sulfate groups inhibited the redox abilities of active species for sulfate catalysts compared with the metal oxide catalysts. The catalytic activities of CeWTi-S and MnWTi-S were seriously decreased in contrast to CeWTi-N and MnWTi-N. The temperature window of CuWTi-S was shifted toward higher temperature comparing with CuWTi-N. The FeWTi-N and FeWTi-S catalysts both showed high NOxconversion in the temperature range between 300°C and 400°C and N2O concentrations for iron-based samples were least among the same kind of catalysts. The abundance of acid sites and weak stability of surface sulfate groups for iron- and copper-based sulfate catalysts might be the main reasons accounting for the better NOxconversion in the medium-temperature range. [ABSTRACT FROM AUTHOR]

The effects of hierarchical porous HZSM-5 zeolites on improving the yield of aromatic hydrocarbons during catalytic fast pyrolysis (CFP) of waste cardboard (WCB) were investigated. Desilicated HZSM-5 zeolites were successfully prepared by alkaline treatment using NaOH solution with different concentrations (0.1 M–0.7 M). A Py-GC/MS apparatus was adopted to carry out the CFP experiments. Results showed that under mild alkaline treatment (NaOH concentration ≤ 0.3 M), the micropores and crystallinity of HZSM-5 were preserved, while the mesopores and weak acid sites increased. The desilicated HZSM-5 zeolites increased the total yield of pyrolytic products from WCB. With regard to the product distribution, carbon yield of aromatics increased dramatically, while that of sugars, carbonyl compounds and other oxygenates decreased obviously. Specifically, HZSM-5 treated by 0.3 M NaOH solution (HZ-0.3 M) was proved to be the most effective catalyst, resulting in a 44% increase of carbon yield of aromatics and an 82% increase of carbon yield of BTX (benzene, toluene and xylenes) comparing to the parent HZSM-5. In addition, the amount of coke deposited on HZ-0.3 M decreased by 29% compared to that on the parent HZSM-5. The retained micropores and the created mesopores of desilicated HZSM-5 zeolites contributed to the enhancement of catalytic performance. However, harsh alkaline treatment of HZSM-5 zeolites (NaOH concentration ≥0.5 M) resulted in the grave collapse of zeolitic crystallinity and the obvious loss of micropores. As a result, the catalytic activities of HZSM-5 zeolites had been weakened. [ABSTRACT FROM AUTHOR]

Catalytic fast pyrolysis is one of the most promising and prevailing technologies for the improvement of bio-oil quality. In this contribution, catalytic fast co-pyrolysis of mushroom waste and waste oil over HZSM-5 zeolite catalyst was conducted to promote the production of aromatics using pyrolysis-gas chromatography/mass spectrometry. The effects of pyrolysis temperature and waste oil to mushroom waste mass ratio on the pyrolytic product distribution were investigated and analyzed. The results showed that with temperature increasing, the relative contents of hydrocarbons increased at first and then decreased, and 600 °C was an optimum temperature as the maximum yield of hydrocarbons could be reached. Besides, the waste oil to mushroom waste mass ratio was of great significance in the catalytic fast co-pyrolysis process, and the total relative contents of hydrocarbons increased with the increasing of waste oil to mushroom waste ratio. On the other hand, a significant synergistic effect between waste oil and mushroom waste was studied during catalytic fast co-pyrolysis, which played an effective role in promoting the production of aromatics remarkably. Catalytic fast co-pyrolysis of waste oil and mushroom waste made a significant contribution to the practical utilization of biomass pyrolysis and provided an effective and efficient way to promote the upgrading of bio-oil. [ABSTRACT FROM AUTHOR]

In order to minimize coke yield during biomass catalytic fast pyrolysis (CFP) process, ethylene diamine tetraacetie acid (EDTA) chemical modification method is carried out to selectively remove the external framework aluminum of HZSM-5 catalyst. X-ray diffraction (XRD), nitrogen (N 2 )-adsorption and ammonia-temperature programmed desorption (NH 3 -TPD) techniques are employed to investigate the porosity and acidity characteristics of original and modified HZSM-5 samples. Py-GC/MS and thermo-gravimetric analyzer (TGA) experiments are further conducted to explore the catalytic effect of modified HZSM-5 samples on biomass CFP and to verify the positive effect on coke reduction. Results show that EDTA treatment does not damage the crystal structure of HZSM-5 zeolites, but leads to a slight increase of pore volume and pore size. Meanwhile, the elimination of the strong acid peak indicates the dealumination of outer surface of HZSM-5 zeolites. Treatment time of 2 h (labeled EDTA-2H) is optimal for acid removal and hydrocarbon formation. Among all modified catalysts, EDTA-2H performs the best for deacidification and can obviously increase the yields of positive chemical compositions in pyrolysis products. Besides, EDTA modification can improve the anti-coking properties of HZSM-5 zeolites, and EDTA-2H gives rise to the lowest coke yield. [ABSTRACT FROM AUTHOR]

In this study, catalytic fast co-pyrolysis (co-CFP) of corn stalk and food waste (FW) was carried out to produce aromatics using quantitative pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS), and ZSM-5 zeolite in the hydrogen form was employed as the catalyst. Co-CFP temperature and a parameter called hydrogen to carbon effective ratio (H/C eff ratio) were examined for their effects on the relative content of aromatics. Experimental results showed that co-CFP temperature of 600 °C was optimal for the formation of aromatics and other organic pyrolysis products. Besides, H/C eff ratio had an important influence on product distribution. The yield of total organic pyrolysis products and relative content of aromatics increased non-linearly with increasing H/C eff ratio. There was an apparent synergistic effect between corn stalk and FW during co-CFP process, which promoted the production of aromatics significantly. Co-CFP of biomass and FW was an effective method to produce aromatics and other petrochemicals. [ABSTRACT FROM AUTHOR]

• The CHP of lignocellulosic biomass was carried out over a hierarchical catalyst. • The products of CFP and CHP of rice husk are compared. • CHP of rice husk (RH) over hierarchical catalyst led to a high hydrocarbons content. • The optimum conditions for the CHP of RH were 400 °C and 35 bar. In this study, we compare the products of catalytic fast pyrolysis (CFP) and catalytic hydropyrolysis (CHP) of rice husk over an HZSM-5-based hierarchical catalyst. The results suggest that the addition of hydrogen inhibits polycondensation reactions, leading to a reduction of 2.3 wt% in coke yield at 400 °C and 35 bar. The presence of hydrogen increases the relative content of hydrocarbons in both liquid and gas products, with a more significant increase in CH 4 and C 2 –C 3 yield in the gas, suggesting that hydrodeoxygenation, decarbonylation, and decarboxylation reactions are promoted. Alkali-treatment of the HZSM-5 improves the catalytic activity and coking resistance of the catalyst. The addition of an extra external MCM-41 layer to the alkali-treated HZSM-5 further improves the catalytic activity, resulting in a relative hydrocarbon content of 48.9%, which is higher than that obtained with the alkali-treated HZSM-5 and pristine HZSM-5. We also report the effect of pressure on the products. As the pressure increases from 1 to 35 bar, the relative content of hydrocarbons increases from 39.9 to 48.9%, while the coke yield decreases from 3.4 to 1.9 wt%, and CH 4 and C 2 –C 3 yields decrease from 10.3 wt% and 5.1 wt% to 14.2 wt% and 6.7 wt%, respectively. As the temperature increases from 300 to 400 °C, the relative content of hydrocarbons increases from 38.2% to 48.9%. Both CH 4 and C 2 –C 3 yields reach the highest values of 14.2 wt% and 6.7 wt% at 400 °C and 35 bar. [ABSTRACT FROM AUTHOR]

To delve into the law of hydrocarbon production in microwave-assisted catalytic fast pyrolysis (MACFP) of corn straw, physical mixed Mesoporous Crystalline Material-41 (MCM-41) and Zeolite Socony Mobile-5 (ZSM-5) catalyst prototypes were exploited in this study. Besides, the effects exerted by temperature of reaction and MCM-41/ZSM-5 mass ratio were explored. As revealed from the results, carbon outputs of hydrocarbons rose initially as the temperature of MACFP rose and reached the maximal data at 550 °C; subsequently, it declined as reaction temperature rose. Moreover, the MCM-41/ZSM-5 mass ratio of 1:2 was second-to-none for hydrocarbon formation in the course of biomass MACFP. It was reported that adding MCM-41 can hinder coke formation on ZSM-5. Furthermore, MCM-41/ZSM-5 mixture exhibited more significant catalytic activity than ZSM-5/MCM-41 composite, demonstrating that hydrocarbon producing process can be stimulated by a simple physical MCM-41 and ZSM-5 catalysts mixture instead of synthesizing complex hierarchically-structured ZSM-5/MCM-41 composite. [ABSTRACT FROM AUTHOR]

To investigate the catalytic pyrolysis performance of complex metal oxide catalysts for biomass, γ-Al2O3 was prepared through the precipitation method, and then ZrO2 and γ-Al2O3 were blended in the proportion of 2:8 using the co-precipitation method. Next, CeO2 was loaded on the surface of the catalyst for further modification. The three catalysts, A, ZA and CZA, were obtained. The specific surface and acidity of the catalysts were characterized by nitrogen adsorption–desorption and NH3-Temperature Programmed Desorption (NH3-TPD) respectively. The catalytic pyrolysis performance of catalysts for bamboo residues was investigated by Pyrolysis gas chromatography mass spectrometry (Py-GC/MS). Chromatograms were analyzed for identification of the pyrolysis products and the relative amounts of each component were calculated. Experimental results indicated that catalyst A had a good catalytic activity for the fast pyrolysis of bamboo residues. The addition of ZrO2 and CeO2 could continuously enhance the acidity of the catalyst and further promote the pyrolysis of macromolecular compounds and deoxidation of oxygen-containing compounds. Finally, catalyst CZA, obtained by compound modification, could not only dramatically reduce the relative content of phenol, acid and aldehyde and other oxygen-containing compounds, but also achieved the maximum hydrocarbon yield of 23.38%. The catalytic performance of catalyst CZA improved significantly compared with catalyst A. [ABSTRACT FROM AUTHOR]