Mesoporous silica-amine beads from blast furnace slag for CO2 capture applications

Steel slag, abundantly available at a low cost and containing over 30 wt% silica, is an attractive precursor for producing high-surface-area mesoporous silica. By employing a two-stage dissolution-precipitation method using 1 M HCl and 1 M NaOH, we extracted pure SiO2, CaO, MgO, etc. from blast furnace slag (BFS). The water-soluble sodium silicate obtained was then used to synthesize mesoporous silica. The resulting silica had an average surface area of 100 m2 g-1 and a pore size distribution ranging from 4 to 20 nm. The mesoporous silica powder was further formed into beads and post-functionalized with polyethyleneimine (PEI) for cyclic CO2 capture from a mixture containing 15% CO2 in N2 at 75 °C. The silica-PEI bead was tested over 105 adsorption-desorption cycles, demonstrating an average CO2 capture capacity of 1 mmol g-1. This work presents a sustainable approach from steel slag to cost-effective mesoporous silica materials and making CO2 capture more feasible.

Commercial SCR catalyst modified with Cu metal to simultaneously efficiently remove NO and toluene in the fuel gas

Developing an environmentally friendly selective catalytic reduction (SCR) catalyst to effectively eliminate both nitric oxides (NO) and toluene has garnered significant attention for regulating emissions from automobiles and the combustion of fossil fuels. This study synthesized a series of novel commercial V2O5-WO3/TiO2 catalysts modified with Cu through the wet impregnation method, which was employed to simultaneously remove NO and toluene from the fuel gas. The assessment of catalyst removal performance was conducted at a selective catalytic reduction system, and the experimental results showed a significant increase in the catalytic activity due to the modification of the copper metal. The 10% Cu/SCR catalyst showed a superior activity that the NO and toluene conversion reached 100% and 95.56% at 300 °C, respectively. Subsequently, various characterization techniques were employed to investigate the crystal phase, morphology, physical features, chemical states, and surface acidity properties of the synthesis catalysts. According to the characterization results, the presence of Cu metal did not have a noticeable impact on the physical property. However, the redox performance was enhanced, and the number of surface acidic sites was also increased after adding Cu to the SCR catalyst. Furthermore, the redox cycle of Cu metal and V species was facilitated to produce more active oxygen which helped to improve the NO and toluene conversion. This work offered a novel perspective into the synergistic oxidation of both NO and toluene, which was potentially relevant for improving the selective catalytic reduction process in coal-fired power plants.

Progress of selective catalytic reduction denitrification catalysts at wide temperature in carbon neutralization

With the looming goal of carbon neutrality and increasingly stringent environmental protection policies, gas purification in coal-fired power plants is becoming more and more intense. To achieve the NOx emission standard when coal-fired power plants are operating at full load, wide-temperature denitrification catalysts that can operate for a long time in the range of 260–420°C are worthy of study. This review focuses on the research progress and deactivation mechanism of selective catalytic reduction (SCR) denitration catalysts applied to a wide temperature range. With the increasing application of SCR catalysts, it also means that a large amount of spent catalysts is generated every year due to deactivation. Therefore, it is necessary to recycle the wide temperature SCR denitration catalyst. The challenges faced by wide-temperature SCR denitration catalysts are summarized by comparing their regeneration processes. Finally, its future development is prospected.

Vanadium-bearing steel slag catalysts for the selective catalytic reduction of NOx by NH3

In this paper, denitration catalysts were prepared by different modification methods using vanadium-bearing steel slag as raw material.

Efficient reduction of nitric oxide using zirconium phosphide powders synthesized by elemental combination method

Zirconium phosphide (ZrP) powders were synthesized by elemental combination method via the direct reaction of zirconium powders with red phosphorus, and characterized by XRD, SEM, XPS, XRF, SAED and TEM measurements. The obtained ZrP powders were found to exhibit apparent activity in the ready eliminateion of nitric oxide (NO) via facile redox reactions, and the elimination dynamics was evaluated within the context of various important experimental parameters, such as reaction temperature and gas concentration. At a fixed amount of ZrP powders, an increasing amount of NO would be eliminated with increasing reaction temperature, and complete conversion of NO to N₂ could be reached in the range of 700 to 800 °C. The addition of NH₃ also facilitated NO elimination at a fixed reaction temperature. Furthermore, of the products of the elimination process, zirconia (ZrO₂) powder is a kind of biocompatible material, red phosphorus can be used to produce safety matches, organophosphorous pesticide and phosphor bronze, and the produced N₂ might be collected and used as a protective gas or be converted into liquid nitrogen for other purposes.