Migration and emissions of selenium during chemical looping combustion of coal

Selenium is one of the most volatile toxic elements in coal, and its emissions must be strictly controlled. Chemical looping combustion (CLC) is a clean and efficient technology for coal. Herein, the iron-based oxygen carrier (OC) was used as an adsorbent to study the migration and emissions of selenium during the CLC of coal. Due to the oxidation and adsorption of selenium by iron-based OC, most of the selenium was retained in OC or distributed in the CO₂ stream. The proportion of gaseous selenium released into the atmosphere was less than 10%—significantly lower than that from the traditional combustion process of coal, which had a value of 91.79%. The presence of OC increased the distribution phase of selenium, promoted the conversion of gaseous selenium to solid selenium, and reduced selenium emissions in flue gas. During CLC of coal, the fuel reactor (FR) temperature and the number of OC re-oxidation cycles played an important role in the emissions and retention of selenium. The increasing FR temperature increased the gaseous selenium in the CO₂ stream, reduced the particulate selenium absorbed by OC, and reduced the selenium emissions in the atmosphere. After 10 continuous CLC cycles, the selenium concentration in OC increased from 0.889 to 8.20 mg kg⁻¹. The continuous cycling of CLC could realize the enrichment of selenium from coal to OC. Furthermore, the migration and transformation mechanism of selenium during CLC was deduced by experiments and thermodynamic simulation. This research provides a suitable reference for reducing selenium emissions and developing CLC technology.     

Deep neural networks for rank-consistent ordinal regression based on conditional probabilities

Pattern Analysis and Applications - In recent times, deep neural networks achieved outstanding predictive performance on various classification and pattern recognition tasks. However, many...     

Directed Urea-to-Nitrite Electrooxidation via Tuning Intermediate Adsorption on Co,Ge Co-Doped Ni Sites

The electrochemical urea oxidation reaction (UOR) is an alternative to electrooxidation of water for energy–saving hydrogen (H₂) production. To maximize this purpose, design of catalysts for selective urea-to-nitrite (NO₂^–) electrooxidation with increased electron transfer and high current is practically important. Herein, a cobalt, germanium (Co, Ge) co-doped nickel (Ni) oxyhydroxide catalyst is reported first time that directs urea-to-NO₂^– conversion with a significant Faradaic efficiency of 84.9% at 1.4 V versus reversible hydrogen electrode and significantly boosts UOR activity to 448.0 mA cm⁻². Importantly, this performance is greater than for most reported Ni-based catalysts. Based on judiciously combined synchrotron-based measurement, in situ spectroscopy and density functional theoretical computation, significantly boosted urea-to-NO₂^– production results from Co, Ge co-doping is demonstrated that optimizes electronic structure of Ni sites in which urea adsorption is altered as NO-terminal configuration to facilitate C N cleavage for *NH formation, and thereby expedites pathway for urea to NO₂^– conversion. Findings highlight the importance of tuning intermediate adsorption behavior for design of high-performance UOR electrocatalysts, and will be of practical benefit to a range of researchers and manufacturers in replacing conventional water electrooxidation with UOR for energy-saving H₂ production.     

Tuning the Chiral Structures from Self-Assembled Carbohydrate Derivatives (Small 25/2023)

Carbohydrates have been regarded as one of the most ideally suited candidates for chirality study via self-assembly owning to their unique chemical structures, abundance, and sustainability. Much efforts have been devoted to design and synthesize diverse carbohydrate derivatives and self-assemble them into various supermolecular morphologies. Nevertheless, still inadequate attention is paid to deeply and comprehensively understand how the carbohydrate structures and self-assembly approaches affect the final morphologies and properties for future demands. Herein, to fulfill the need, a range of recently published studies relating to the chirality of carbohydrates is reviewed and discussed. Furthermore, to tune the chirality of carbohydrate-based structures on both molecular and superstructural levels via chirality transfer and chirality expression, the designing of the molecules and choosing of the proper approaches for self-assembly are elucidated.