Xiaolong Liu

Catalytic oxidation of toluene over a porous Co3O4-supported ruthenium catalyst

Porous Co3O4-MOF and Ru/Co3O4-MOF were prepared through a metal–organic frameworks (MOFs)-templated method, and the bulk materials resulted from precipitation method were prepared for comparison. All catalysts were tested for the catalytic oxidation of toluene in the temperature range of 150–300 °C, and Ru/Co3O4-MOF showed apparently higher catalytic activity and CO2 selectivity than other materials. The influence of water vapour on the catalytic oxidation of toluene was studied at 235 °C and 245 °C, and it could be found that the inhibition effect weakened with the increase of temperature. Additionally, the test of 12 h on-stream reaction was conducted to explore the stability of Ru/Co3O4-MOF.

Catalytic oxidation of methyl bromide using ruthenium-based catalysts

Ruthenium-based catalysts Ru/TiO2, Ru/SiO2, Ru/γ-Al2O3, and Ru/ZrO2 were prepared and evaluated for CH3Br oxidation, and Ru/TiO2 showed better catalytic performance than the other samples. The product yields and selectivities were also studied. The thermal stability was examined with a 48 h on-stream test. The influence of water vapor on the catalytic oxidation of CH3Br was studied at 210 °C and 230 °C, and it was found that the inhibition effect weakened with the increase in temperature. Additionally, Ru/TiO2 was also employed in the catalytic oxidation of CO, benzene, methyl acetate, and multi-pollutants of simulated PTA offgas.

Simultaneous removal of PCDD/Fs and NOx from the flue gas of a municipal solid waste incinerator with a pilot plant

The pilot-scale plant on the simultaneous removal of PCDD/Fs and NOx from the flue gas of a municipal solid waste incinerator is presented. In order to research the influence of temperature on the catalytic decomposition of PCDD/Fs and the selective catalytic reduction of NOx, the experiments were performed at 220 °C, 260 °C, and 300 °C, and the congener profiles of PCDD/Fs for the samples collected at the inlet and outlet were illustrated. Noteworthy, the detailed congener distributions of PCDD/Fs in the gas-phase and particle-phase of the inlet and 300-outlet (decomposition temperature = 300 °C) samples are presented, and the removal efficiencies η(g-I-TEQ) and η(p-I-TEQ) reached to 94.94% and 99.67%, respectively. The effect of the SCR process on the removal of PCDD/Fs was also studied at a relatively low temperature of 220 °C. Additionally, the NOx emissions and the SCR efficiencies were investigated.

Gas-solid catalytic reactions over ruthenium-based catalysts

Ruthenium (Ru)-based catalysts are widely employed in several types of gas-solid reactions because of their high catalytic activities. This review provides theoretical research on Ru-based catalysts and an analysis of their basic properties and oxidation behavior. There is particular emphasis on Ru-catalyzed gas-solid catalytic reactions, including the catalytic oxidation of VOCs, preferential oxidation of CO, synthesis of ammonia, oxidation of HCl and partial oxidation of CH 4 . Recent literature on catalysis is summarized and compared. Finally, we describe current challenges in the field and propose approaches for future development of Ru-based catalysts.

Gas-phase and particle-phase PCDD/F congener distributions in the flue gas from an iron ore sintering plant

The activated carbon injection-circulating fluidized bed (ACI-CFB)-bag filter coupling technique was studied in an iron ore sintering plant. For comparison, the removal efficiencies under the conditions without or with ACI technology were both evaluated. It was found that the polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/F) removal efficiency for total international toxic equivalence quantity (I-TEQ) concentration was improved from 91.61% to 97.36% when ACI was employed, revealing that ACI was very conducive to further controlling the PCDD/F emissions. Detailed congener distributions of PCDD/Fs in the gas-phase and particle-phase of the Inlet and Outlet samples were determined. Additionally, the PCDD/F distribution for the Fly ash-with ACI sample of was also studied.

Catalytic oxidation of benzene over ruthenium–cobalt bimetallic catalysts and study of its mechanism

In this work, ruthenium-based bimetallic catalysts of the formula Ru–5M/TiO2 (M = Mn, Co, Ce, Cu, Fe) were prepared and evaluated in benzene oxidation, and Ru–5Co/TiO2 exhibited the lowest complete oxidation temperature (220 °C), demonstrating Co3O4 as the best dopant. The influence of the Ru and Co contents on the catalytic activity was also studied, and 1 wt% Ru and 5 wt% Co3O4 were confirmed. Water vapor showed an inhibition effect on benzene oxidation at 210 °C, whereas the catalytic efficiency was barely influenced at a higher temperature (230 °C). STEM analyses revealed that Ru–Co bimetallic species showed similar distributions on the catalytic surface. Based on the correlation of the catalytic results with various characterization techniques, the synergistic effect between Ru and Co was well demonstrated, and a four-step transformation in the oxidation process was concluded. Besides, systematic in situ FTIR studies for benzene oxidation over Ru/TiO2, Co/TiO2, and Ru–5Co/TiO2 were conducted and compared, and many organic intermediates were observed in the in situ FTIR spectra. Accordingly, the reaction mechanism for benzene oxidation over the Ru–Co bimetallic catalyst was proposed.

Catalytic oxidation of chlorobenzene over noble metals (Pd, Pt, Ru, Rh) and the distributions of polychlorinated by-products

Catalytic oxidation of chlorobenzene over noble metal catalysts Pd/TiO2, Pt/TiO2, Ru/TiO2, and Rh/TiO2 was evaluated, and Ru/TiO2 contributed the highest catalytic activity and CO2 selectivity. During the oxidation, polychlorinated benzenes PhClx (x ≥ 2) were observed, and Ru/TiO2 showed apparently lower PhClx concentrations than other three samples. With the improvement of temperature, the maximum concentration appeared in the sequence of dichlorobenzene (PhCl2), trichlorobenzene (PhCl3), tetrachlorobenzene (PhCl4), and pentchlorobenzene (PhCl5), whereas the concentration of hexachlorobenzene (PhCl6) was always low and showed no apparent regularity. Besides, the dioxin-like PCBs (dl-PCBs) were collected and analyzed for Pd/TiO2 and Ru/TiO2. The ∑dl-PCBs produced by Pd/TiO2 (0.0055 ng WHO-TEQ/Nm3) was about 1.5 times that of Ru/TiO2 (0.0027 ng WHO-TEQ/Nm3). XPS analyses revealed that Ru/TiO2-used and Rh/TiO2-used gave the lowest and the highest Cl content of 0.61% and 1.87%. Ru/TiO2-used afforded the lowest (Clad+Clor)/Cl value (22.1%) and the highest Clbr/Cl value (77.9%), which might be an important reason for its strongest chlorine removal ability and the lowest yields of polychlorinated by-products, whereas other three catalysts showed similarity in the Cl distributions. Additionally, systematic in-situ FTIR studies were conducted, and a reaction mechanism for the catalytic oxidation of chlorobenzene was proposed.

Catalytic oxidation of ethyl acetate over LaBO3 (B = Co, Mn, Ni, Fe) perovskites supported silver catalysts

A series of silver catalysts supported on lanthanum based perovskites LaBO3 (B = Co, Mn, Ni, Fe) were synthesized and evaluated in the catalytic oxidation of ethyl acetate. XRD, BET, TEM/HRTEM, HAADF-STEM, XPS and H2-TPR were conducted, and the results indicate that redox activity of the catalysts is of great importance to the oxidation reaction. Activity tests demonstrated that Ag/LaCoO3 was more active than the other samples in ethyl acetate oxidation. Moreover, the CO2 selectivity, COx yields and byproduct distributions for all catalysts were studied, and Ag/LaCoO3 showed the best catalytic performance. Besides, Ag/LaCoO3 also showed excellent catalytic activity for other OVOCs.