Mo-modified ZSM-5 catalysts were prepared and used to produce aromatic hydrocarbons during catalytic fast pyrolysis (CFP) of biomass. The composition and distribution of aromatics were investigated on pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The reaction factors, such as the Mo content, the reaction temperature and the catalyst/biomass mass ratio, were also optimized. It was found that the 10Mo/ZSM-5 catalyst displayed the best activity in improving the production of monocyclic aromatic hydrocarbons (MAHs) and decreasing the yield of polycyclic aromatic hydrocarbons (PAHs) at 600 °C and with a catalyst/biomass ratio of 10. Furthermore, according to catalyst characterization and the experiment results, the aromatics formation mechanism over Mo/ZSM-5 catalysts was also summarized and proposed.
ZrO2 and catalysts were prepared by a co-precipitate method and coupled with a HZSM-5 zeolite catalyst through a mechanical mixing method; these were applied to the direct synthesis of aromatic hydrocarbons from syngas through an oxygen-containing intermediate route. The physical and chemical properties of the catalysts were characterized by XRD, H2-TPR, CO2-TPD, and SEM methods. The comparative catalytic effects of ZrO2 and MgZrOx catalysts were discussed under different reaction conditions. The reaction results showed that the addition of Mg to a ZrO2 catalyst reduced the selectivity of CO2 by inhibiting the water–gas conversion reaction, and increased the selectivity of aromatics and the proportion of BTX in aromatic products.
In the present work, LDHs-derived Ni–Al nanosheet arrays (NiAl/NA) were successfully synthesized via a one-step hydrothermal method, and applied in the steam-reforming of glycerol reaction for enhanced and stable hydrogen production. The physicochemical properties of catalysts were characterized using various techniques, including XRD, SEM–EDS, XPS, N2-physisorption, Raman, and TG–DTG. The results indicate that smooth and cross-linked Ni–Al mixed metal oxide nanosheets were orderly and perpendicularly grown on the Ni foam substrate. The SEM line scan characterization reveals the metal concentration gradient from the bottom to the top of nanosheet, which leads to distinctly optimized Ni valence states and an optimized binding strength to oxygen species. Owing to the improved reducibility and more exposed active sites afforded by its array structures, the NiAl/NA catalyst shows enhanced glycerol conversion (83.1%) and a higher H2 yield (85.4%), as well as longer stability (1000 min), compared to the traditional Ni–Al nanosheet powder. According to the characterization results of spent catalysts and to density functional theory (DFT) calculations, coke deposition is effectively suppressed via array construction, with only 1.25 wt.% of amorphous carbons formed on NiAl/NA catalyst via CO disproportionation.
1 April 2020 in Journal of Biobased Materials and Bioenergy
The objective of this study is to catalytically upgrade fast pyrolysis vapors of sawdust using various Fe-based catalysts for producing phenolic-rich bio-oil by analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique. A variety of parameters, including support characteristic, calcination temperature, pyrolysis temperature, as well as the catalyst-to-biomass ratio during the pyrolysis process were evaluated for their effects on product distribution of bio-oil. GC-MS analysis showed that compared to Fe–Mg and Fe–Al catalysts, the developed Fe–Ca catalyst significantly promoted the formation of phenols and its derivatives. The phenolic concentration declined with increasing calcination temperature and pyrolysis temperature, while increased monotonically along with increasing catalyst-to-biomass ratio. The phenolics concentration was high upto 81% (peak area) under optimum conditions of calcination temperature of 500 °C, pyrolysis temperature of 600 °C and catalyst-to-biomass ratio of 10. At higher catalyst-to-biomass ratio of 20, phenolics (88.03% in peak area) and hydrocarbons (including 7.86% of aromatics and 4.1% aliphatics) were the only two components that can be detected, with all the acids, aldehydes and ketones completely eliminated. This indicated the excellent capability of developed Fe–Ca catalyst in promoting the decomposition of lignin in biomass to generate phenolic compounds and meanwhile inhibiting the devolatilization of holocellulose.
The proper disposal of antibiotic mycelial residue (AMR) is a critical concern due to the spread of antibiotics and environmental pollution. Pyrolysis emerges as a promising technology for AMR treatment. In this study, we investigated the effect of pyrolysis temperature on the thermal decomposition behavior and product characteristics of avermectin (AV) mycelial residues. Various characterization techniques were employed to analyze thoroughly the compositions and yields of the obtained gas, liquid, and biochar products. The results indicated that most of the organic matter such as protein, carbohydrate, and aliphatic compounds in AV mycelial residues decomposed intensely at 322 °C and tended to end at 700 °C, with a total weight loss of up to 72.6 wt%. As the pyrolysis temperature increased, the biochar yield decreased from 32.81 wt% to 26.39 wt% because of the enhanced degradation of volatiles and secondary reactions of the formed aromatic rings. Accordingly, more gas components were formed with the gas yield increased from 9.76 wt% to 15.42 wt%. For bio-oil, the contents were maintained in the range of 57.43–60.13 wt%. CO and CO2 dominated the gas components with a high total content of almost 62.37–97.54 vol%. At the same time, abundant acids, esters (42.99–48.85%), and nitrogen-containing compounds (32.14–38.70%) such as nitriles, amides, and nitrogenous heterocyclic compounds were detected for the obtained bio-oil. As for the obtained biochars, particle accumulation and irregular pores were presented on their bulk surface, which was primarily composed of calcium oxalate (CaC2O4) and calcium carbonate (CaCO3). This work can provide theoretical insights for the harmless disposal and resource recovery for AMR, contributing significantly to the field of solid waste reuse and management.