Physicochemical properties and desulfurization activities of metal oxide/biomass-based activated carbons prepared by blending method

Preparation of Manganese Blending-Modified Activated Coke for Flue Gas Desulfurization

In this study, the preparation and desulfurization application of MnO₂ and pyrolusite blending-modified activated cokes (ACM and ACP) were studied. Thermodynamic calculation shows that the blended metal oxides could be reacted with the solid carbon and gaseous products H₂, CO, and CO₂ for activation. The physicochemical properties of the blending-modified ACP and ACM responded considerably differently to preparation conditions. The blended metal oxide significantly improved the mesoporous structure of the modified activated cokes, as well as the surface acidic and basic functional groups. Different metal oxides played different roles in the pore structure and surface functional group evolution, and the current investigation indicates that MnO₂ is more favorable than pyrolusite. The enhanced acidic and basic functional groups, coupled with the catalysis of metal oxides, improved the desulfurization performance of the modified activated cokes. The sulfur capacities of the prepared ACP and ACM were 47.9-208.9 and 119.4-205.9 mg/g, respectively, which were much greater than the sulfur capacity of the fresh activated coke.

Effects of Activation Conditions on the Properties of Sludge-Based Activated Coke

Sewage sludge and waste biomass are unavoidable byproducts of municipal and industrial processes. Both materials have significant carbon contents. Activated coke with a developed pore structure can be obtained after its physical activation. In this study, sewage sludge and waste poplar bark were used as precursor materials to prepare activated coke by steam, carbon dioxide gas, and their mixtures. The effects of different concentrations of activation gas on the activated coke product were investigated. Through nitrogen adsorption analysis, it was found that activated coke has a higher specific surface area and better pore structure when activated in gas containing 20% steam. The activated coke prepared by carbon dioxide gas activation has higher microporosity than that prepared by steam activation. Infrared spectrum analysis shows that steam activation is beneficial to the formation of free hydroxyl functional groups. Through scanning electron microscopy analysis, the pores of activated coke prepared by steam activation appeared to extend deeper in the structure of the coke, while the pores of activated coke prepared by carbon dioxide activation appeared to have fine circular structures. The activated coke prepared by the activation of mixed gas appeared to have ablated particles on the surface due to the ablation of the pore structure. In order to prepare activated coke with excellent adsorption performance, the physical and chemical properties of activated coke under different activation conditions were studied in detail.

Catalytic Steam Reforming of Bio-Oil-Derived Acetic Acid over CeO2-ZnO Supported Ni Nanoparticle Catalysts

The steam reforming of bio-oil-derived acetic acid over the developed Ni/CeO₂-ZnO nanoparticle catalysts for hydrogen production was studied. The correlations of CeO₂ to ZnO mass ratio (CZMR) and nickel loading with the properties and performances of Ni/CeO₂-ZnO catalysts were explored. The H₂, CO, and potential H₂ yields followed a Gaussian normal distribution with increasing the CZMR. An exponential function equation was established to correlate the H₂, CO, and potential H₂ yields with Ni loading. As the CZMR increased from 0 to 1/3, the H₂ yield increased from 57.8 to 69.4%, with a growth rate of 20.1%. Further, on increasing the CZMR from 1/3 to 3, the H₂ yield decreased by 37.6%. The CO yield showed a similar trend for the H₂ yield on increasing the CZMR, which first increased to a peak value, then started to decrease rapidly and finally stabilized. The yield of H₂ increased significantly from 20.6 to 73.5%, with the increase of nickel loading from 0 to 15%. Further, on increasing the nickel loading from 15 to 25%, the H₂ yield increased by only 5.8%. With the CZMR of 1/3 and the nickel loading of 15%, the selectivities of H₂ and CO were as high as 91.6 and 42.3%, respectively.

The effects of metal oxide blended activated coke on flue gas desulphurization

The objective of this study was to investigate the possibility of using some natural minerals or industrial waste containing some metal oxides to prepare modified activated coke (M/AC) for flue gas desulphurization.

Physicochemical characteristics and desulphurization activity of pyrolusite-blended activated coke

In this study, a novel activated coke (AC-P) was prepared by the blending method using bituminous coal as the raw material and pyrolusite as the catalyst. The physicochemical properties of prepared activated coke (AC) were characterized by BET, Fourier-Transform Infrared Spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results indicated that the blended pyrolusite had a slight effect on the structural properties of AC, while the oxygenated functional groups on AC were increased and MnO2 and Fe2O3 in pyrolusite were reduced to MnO and Fe on the AC-P samples, respectively. All the AC-P samples significantly improved the removal of SO2, with the highest sulphur capacity (153 mg/g) for the AC blended with 8 wt% pyrolusite, which was 57.7% higher than that of the blank activated cock. This could be mainly attributed to the change in surface chemical properties of the AC-P samples and the active catalytic components in pyrolusite for the catalytic oxidation of SO2 in desulphurization process.