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Herein, SnxCe1−xO2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1) catalysts have been synthesized by a co-precipitation method and their catalytic performance for soot oxidation in the presence of water is investigated. The results show that the catalyst with the optimal mole ratio (Sn : Ce = 4 : 6) exhibits the best catalytic performance, providing a T90 value of 413 °C and 92.8% CO2 selectivity. The characterization results reveal that the incorporation of Sn4+ into the lattice of CeO2 can result in the decrease of crystallite size and the improvement of Oα (the chemisorbed oxygen) and Ce3+ contents, which is beneficial for the enhancement of catalytic performance. The mesoporous structure and the increased specific surface area enhance the contact condition between the catalyst and soot. The presence of Sn converts Ce4+ to Ce3+, which increases the adsorbed oxygen content of the catalyst. The improvement of the redox activity and defective sites enhances the adsorption and activity properties of oxygen species. Moreover, repeat experiments were carried out to explore the durability. [ABSTRACT FROM AUTHOR]

Bi2O3–Fe2O3 system catalysts were synthesized by a hydrothermal method in different ratios. Six materials were synthesized: Fe2O3, Bi2O3, Bi2O3/Fe2O3, BiFeO3, Bi2Fe4O9 and Bi25FeO40. The resulting catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), H2-temperature-programmed reduction (TPR), and O2-temperature-programmed desorption (TPD) measurements, and X-ray photoelectron (XPS) and Raman spectroscopies, in order to investigate their physical–chemical properties and to detect soot combustion through temperature-programmed experiments. XPS and O2-TPD measurements show that composite catalysts have higher amounts of active oxygen than pure catalysts. The ratio of active oxygen is the largest in the Bi0.2Fe1.8 catalyst. All of the composite catalysts show superior low temperature catalytic activity than single Bi2O3 or Fe2O3 catalysts, and the Bi0.2Fe1.8 catalyst shows a minimum T90 of 422 °C with the best catalytic properties, because Bi2O3 is able to increase the formation of oxygen vacancies by accelerating the transport rate of the active oxygen species (O2−) for its high mobility and reactivity at the Bi–Fe interface layer. The mechanism of the Bi0.2Fe1.8 catalyst in the catalytic oxidation of soot is discussed. [ABSTRACT FROM AUTHOR]

Graphical Abstract Highlights • The Diels-Alder reaction was used for aromatics production during the segmented co-pyrolysis of biomass and HDPE. • High selectivity of aromatics (95.9%) bio-oil was obtained. • The synergistic effect was promoted by using MgCl 2 and HZSM-5 in the segmented co-pyrolysis of biomass and HDPE. Abstract For the catalytic co-pyrolysis of glucose and high-density polyethylene (HDPE) in a fixed-bed reactor, the effects of different layout schemes of feedstock and catalysts on bio-oil yield and aromatics selectivity were investigated based on the Diels-Alder reaction of furans and short-chain olefins on HZSM-5 for aromatics production. Experimental results showed that the arrangement (HDPE/HZSM-5/glucose/HZSM-5) had advantages on bio-oil yield and aromatics selectivity. A mixture of pine sawdust and MgCl 2 as a glucose substitute that provided furan compounds (Furfural) reacted with short-chain olefins for aromatics production. We found that acquiring high selectivity of aromatic bio-oil from the catalytic co-pyrolysis of pine sawdust and HDPE with MgCl 2 and HZSM-5 is feasible. The effects of co-pyrolysis temperature, biomass to HDPE ratio, and feedstock to catalyst ratio on bio-oil yield and chemical compositions were discussed. Notably, an appropriate ratio between the amounts of furans and short-chain olefins is necessary for increasing bio-oil yield and aromatics selectivity. Maximum oil phase product yield of 20.6% and aromatics selectivity (area %) of 95.9% were obtained when pyrolysis temperature, biomass to HDPE ratio, and feedstock to catalyst ratio were 600 ℃, 1:2, and 1:1, respectively. [ABSTRACT FROM AUTHOR]