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Microwave-assisted pyrolysis of Chinese tallow kernel oil with silicon carbide (SiC)-foamed ceramic catalyst in a downdraft reactor was carried out in this study. In this paper, we studied the influence of catalytic temperature, catalyst-to-feed ratio, and feeding rate on product distribution and chemical components of bio-oil. The aromatic proportion reached a maximum value of 89.707 wt% when catalytic conditions were set as follows: 300 °C catalytic temperature, 1:2 catalyst/feedstock ratio, and 1 ml/min feed rate. Fourier-transform infrared spectra were consistent with the results obtained from gas chromatography–mass spectrometry. Their outstanding thermal stability allowed SiC-foamed ceramics to perform well in five cycles of repeated experiments under optimal conditions. These results indicate that the SiC-foamed ceramics are promising catalysts for aromatic production in microwave-assisted pyrolysis of Chinese tallow kernel oil in a downdraft reactor. This pathway can also improve the application prospects of microwave pyrolysis technology. [ABSTRACT FROM AUTHOR]

Graphical abstract The effect of hydrothermal pretreatment on aromatic formation during co-pyrolysis of biomass and polyethylene has been illustrated. Highlights • Understanded the biomass structure changes in depth during hydrothermal pretreatment. • The destroyed biomass recalcitrance facilitated the formation of aromatic. • More aromatics were produced due to the removal of AAEM and hemicellulose and increased H/C eff ratio. • Effect of hydrothermal pretreatment on aromatic formation was illustrated. Abstract The effect of hydrothermal pretreatment (HTP) on the biomass structure and aromatic production in the catalytic co-pyrolysis process was investigated in this study. Fundamental characteristic analysis indicated that HTP removed most of the hemicellulose and some oxygen, enhancing the hydrogen-to-carbon effective ratio (H/C eff) of biomass. X-ray diffraction, Fourier-transform infrared spectroscopy, and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance analysis revealed that HTP mainly interrupted unstable chemical bonds (acetyl groups, glycosidic bonds, and ether linkage in lignin) and changed the biomass crystallinity. Furthermore, HTP remarkably removed alkalis and alkali earth metals (AAEM) from the biomass. To determine the effect of HTP on co-pyrolysis, individual pyrolysis of raw and pretreated corncob was carried out. Results showed that HTP significantly enhanced yields of levoglucosans and furans, both of which are important intermediates for aromatic formation during co-pyrolysis. HTP remarkably increased the aromatic contents of bio-oil in the co-pyrolysis of different corncob samples and polyethylene. The influence of HTP on aromatic production mainly included AAEM removal, hemicellulose decomposition, furan formation, and H/C eff increments in the pretreated biomass. Thus, HTP has great potential in improving aromatic production during co-pyrolysis of biomass and polyethylene. [ABSTRACT FROM AUTHOR]

Graphical abstract Value-added bio-oil with high selectivities of aromatics is produced via catalytic fast pyrolysis of torrefied corn cob over Ni-modified hierarchical ZSM-5 catalyst. Highlights • NaOH solution treatment and Ni modification significantly change the properties of catalyst. • Ni/hierarchical ZSM-5 catalysts for upgrading of torrefied corn cob pyrolysis vapors. • Obtained bio-oil is enriched in aromatics especially mono-aromatics. • Kinetic analysis of catalytic pyrolysis process is conducted to understand thermal behaviors. Abstract Catalytic fast pyrolysis (CFP) of torrefied corn cob using Ni-modified hierarchical ZSM-5 catalyst was conducted in this study. The prepared catalysts were characterized by N 2 adsorption and desorption (N 2 -BET), X-ray diffraction (XRD), and temperature-programmed desorption of NH 3 (NH 3 -TPD). NaOH solution treatment resulted in the lower peak intensities of hierarchical ZSM-5 catalyst in the XRD patterns while Ni modification improved the catalyst framework. In addition, NaOH solution treatment created some mesopores or macropores, but the incorporation of Ni reduced BET surface area and volume of micropores. Though the addition of Ni lowered the acidity of catalyst, Ni-modified hierarchical ZSM-5 catalyst led to higher yields and of aromatic hydrocarbons. What is more, hierarchical ZSM-5 catalysts significantly improved the selectivities of mono-aromatics. Kinetic analysis shows that CFP of torrefied corn cob was second-order reaction and the addition of Ni can obtain a lower activation energy compared with hierarchical ZSM-5 catalyst. [ABSTRACT FROM AUTHOR]

Microwave-assisted catalytic fast co-pyrolysis using HZSM-5 as catalyst was tested on soapstock and waste tire. Effects of co-pyrolysis temperature, catalyst to feed ratio and soapstock to tire ratio on product fractional yields and chemical composition were studied. Experimental results indicated that the optimal co-pyrolysis temperature was 550 °C, where the highest yield of bio-oil and proportion of aromatics in the bio-oil was obtained. The use of catalyst enhanced the proportion of aromatics, but reduced the yield of bio-oil. Waste tire presented a significant synergistic effect with soapstock to facilitate the production of aromatics in the bio-oil. In addition, the char as a by-product can be used as soil amendment or solid fuel. [ABSTRACT FROM AUTHOR]

This study investigated the microwave-assisted catalytic fast pyrolysis (MACFP) of straw stalk and soapstock with HZSM-5 as a catalyst. The effects of pyrolysis temperature, catalyst:feed ratio, and straw stalk:soapstock ratio on bio-oil yield and composition were discussed. Results showed that temperature greatly influenced the yield and product distribution of bio-oil. The maximum bio-oil yield and highest proportion of aromatic hydrocarbons were obtained at 550 °C. Adding HZSM-5 decreased bio-oil yield but improved bio-oil quality. Co-feeding straw stalk and soapstock can improved the proportion of aromatic and aliphatic compounds. The optimal range of straw stalk:soapstock ratio was 1:1 to 1:2. Moreover, biochar is rich in various essential elements and can be used as good soil amendment. [ABSTRACT FROM AUTHOR]

• Composite catalysts (ZSM-5/MCM-41) were synthesized and its optimum catalytic conditions were studied. • Microwave-assisted catalytic fast co-pyrolysis (co-MACFP) was adopted in this experiment. • The synergistic effect of lignin and catalyst promotes the formation of aromatic compounds. Microwave-assisted catalytic fast co-pyrolysis (MACFP) of lignin and waste oil with SiC as microwave absorbent and hierarchical ZSM-5/MCM-41 as catalyst were implemented in a microwave-induced reactor. ZSM-5/MCM-41 is a kind of composite catalyst with MCM-41 as shell and ZSM as core. The effects of catalyst temperature, the ratio of feedstock-to-catalyst and the ratio of two reactants (lignin and waste oil) on product distribution and yield were studied. The study shows that catalytic co-pyrolysis is a complex reaction process, and many reaction conditions could affect the final reaction results. The optimum reaction conditions are as follows: catalytic temperature 400 °C, the feedstock-to-catalyst ratio of 10:1 and the ratio of lignin to waste oil of 2:1. Under this reaction condition, the conversion of feedstocks reached 76.00%, the proportion of aromatics was 50.31% and the selectivity of monocyclic aromatic hydrocarbons (MAHs) was 42.83%. [ABSTRACT FROM AUTHOR]