Assisting effect of Al_(2)O_(3) on MnO_(x) for NO catalytic oxidation

Various Mn-based catalysts for NO oxidation were prepared using MnO_(x)as active compound,while Ti O_(2)and Al_(2)O_(3)were adopted as catalyst support.The performance of the catalysts was tested to study the effect of support on Mn-based catalyst activity.Performance of the catalysts followed as Mn_(0.4)/Al>Mn_(0.2)/Al>Mn_(0.4)/Ti>Mn_(0.2)/Ti>MnO_(x)>Al_(2)O_(3)on the whole,indicating the synergism of MnO_(x)and Al_(2)O_(3)for NO catalytic oxidation.Results were analyzed according to characterization data.Adsorbed oxygen on catalyst rather than lattice oxygen was detected as the active oxidizer for NO oxidation.As catalyst support,Al_(2)O_(3)provided more sites to carry surface adsorbed oxygen than TiO_(2),resulting in the presence of more active oxygen on Mn O_(x)/Al_(2)O_(3)than on MnO_(x)/TiO_(2).Moreover,MnO_(x)/Al_(2)O_(3)possessed high surface area and pore volume,which greatly benefited the adsorption of NO on catalyst and further favored the oxidation of NO by active oxygen.All these advantages helped Mn_(0.4)/Al exhibited the best catalytic efficiency.

企业危险废物日常管理中典型违法行为和减量化措施

企业目前在危险废物管理方面还相对薄弱,在危险废物日常管理中存在诸多违法不合规行为,本文根据可公开的行政处罚信息和案例,总结了企业危险废物日常管理中典型的违法行为。并根据企业产生的典型危险废物特点,从源头管控、强化管理、工艺技术优化升级改造、危险废物资源化利用等方面提出危险废物减量化措施建议,为企业主管人员日常规范化管理危险废物提供参考。

2D Ca/Nb-based perovskite oxide with Ta doping as highly efficient H_(2)O_(2)synthesis catalyst

Perovskite oxides(POs)are emerging as a class of highly efficient catalysts for reducing oxygen to H_(2)O.Although a rich variety of POs-based catalysts have been developed by tuning the complex composition,a highly efficient PO catalyst that is able to alter the reaction pathway from a 4e−process to a 2e−process for H_(2)O_(2)production has rarely been achieved.We modified the structure and composition of a Ca-and Nb-based PO material by realizing a uniform two-dimensional(2D)morphology and varied Ta doping,resulting in the 2D Ca_(2)Nb_(3−x)Ta_(x)O_(10)−(x=0,0.5,1,and 1.5)monolayer catalysts.The obtained catalysts exhibit a dominant 2e−pathway and show exceptional H_(2)O_(2)production efficiency.The typical Ca_(2)Nb_(2.5)Ta_(0.5)O_(10)−nanoflakes showed an onset potential of 0.735 V vs.reversible hydrogen electrode(RHE),a remarkably high selectivity over 95%across a wide range of 0.3-0.7 V,an impressively high Faradaic efficiency of 94%,and a notable H_(2)O_(2)productivity of 1571 mmol·gcat^(−1)·h^(−1).These findings highlight the great potential of 2D perovskite oxide nanoflakes as advanced electrocatalysts for 2e−oxygen reduction reaction.

Cascading V_(2)O_(3)/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries (LIBs), aqueous Zn-ion batteries (ZIBs) have been getting a lot of attention because of their cost-effectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivalence. However, vanadium oxide cathodes still suffer from unsatisfactory capacity, poor stability, and low electrical conductivity. In this work, cascading V_(2)O_(3)/nitrogen doped carbon (V_(2)O_(3)/NC) hybrid nanosheets are prepared for high-performance aqueous ZIBs by pyrolyzing pentyl viologen dibromide (PV) intercalated V_(2)O5 nanosheets. The unique structure features of V_(2)O_(3)/NC nanosheets, including thin sheet-like morphology, small crystalline V_(2)O_(3) nanoparticles, and conductive NC layers, endow V_(2)O_(3)/NC with superior performance compared to most of the reported vanadium oxide cathode materials for aqueous ZIBs. The V_(2)O_(3)/NC cathode exhibits the discharge capacity of 405 mAh/g at 0.5 A/g, excellent rate capability (159 mAh/g at 20 A/g), and outstanding cycling stability with 90% capacity retention over 4000 cycles at 20 A/g.

Experimental studies of ash film fractions based on measurement of cenospheres geometry in pulverized coal combustion

In pulverized coal particle combustion, part of the ash forms the ash film and exerts an inhibitory influence on combustion by impeding the diffusion of oxygen to the encapsulated char core, while part of the ash diffuses toward the char core. Despite the considerable ash effects on combustion, the fraction of ash film still remains unclear. However, the research of the properties of cenospheres can be an appropriate choice for the fraction determination, being aware that the formation of cenospheres is based on the model of coal particles with the visco-plastic ash film and a solid core. The fraction of ash film X is the ratio of the measuring mass of ash film and the total ash in coal particle. In this paper, the Huangling bituminous coal with different sizes was burnt in a drop-tube furnace at 1273, 1473, and 1673 K with air as oxidizer. A scanning electron microscope (SEM) and cross-section analysis have been used to study the geometry of the collected cenospheres and the effects of combustion parameters on the fraction of ash film. The results show that the ash film fraction increases with increasing temperature and carbon conversion ratio but decreases with larger sizes of coal particles. The high fraction of ash film provides a reasonable explanation for the extinction event at the late burnout stage. The varied values of ash film fractions under different conditions during the dynamic combustion process are necessary for further development of kinetic models.