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.
Biomass thermochemical conversion with in situ CO2 capture is a promising technology in the production of high-quality gas. The adsorption competition mechanism of gas molecules (H2O, CO2, CO, CH4, and H2) on CaO-based catalyst surfaces was studied using density functional theory (DFT) and experimental methods. The adsorption characteristics of CO2 on CaO and 10 wt % Ni/CaO (100) surfaces were investigated in a temperature range of 550–700 °C. The adsorption energies were increased and then weakened, reaching their maximum at 650 °C. The simulation results were verified by CO2 temperature-programmed desorption (CO2-TPD) experiments. By the density of states and Mulliken population analysis, CaO doped with Ni caused a change in the electronic structure of the Osurf atom and decreased the C–O bond stability. The molecular competition mechanism on the CaO-based catalyst surface was identified by DFT simulation. As a result, the adsorption energies decreased in the following order: H2O > CO2 > CO > CH4 > H2. The increase of CO2 adsorption energy on the 10 wt % Ni/CaO surface, compared with the CaO surface, was the largest among those of the studied molecules, and its value increased from 1.45 eV to 1.81 eV. Therefore, the 10 wt % Ni/CaO catalyst is conducive to in situ CO2 capture in biomass pyrolysis.
The effects of ash and slag from a biomass power plant on the compressive strength, setting time and fluidity of the pastes of Portland cement (P.O) and sulfoaluminate cement (SAC) were studied, and the hydration products and microstructure at the age of 7 days were analyzed via XRD, SEM and other test methods. The results show that the compressive strength of the composite cementitious material decreases, the setting time prolongs and the fluidity increases with the increase in the ash and slag content in the power plant. The microscopic analysis shows that the ash and slag of the biomass power plant can promote the hydration of Portland cement and sulfoaluminate cement paste, and increase the generation of hydration products. The results showed that replacing SAC clinker with 20–30% biomass power plant ash (BPPA) decreased the cement strength, and that an appropriate amount of BPPA (10–15%) could significantly improve the mechanical strength of SAC blended cement. The compressive strength of blended BPPA composite cementitious material in 28 days could reach 60 MPa. This study provided solutions to utilizing the BPPA as a building material admixture to minimize the consumption of energy-intensive cement and to meet the growing needs of the construction industry.
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.