Methylation of 2-Methylnaphthalene with Methanol over NH_4 F and Pt Modified HZSM-5 Catalysts

Shape-selective methylation of 2-methylnaphthalene (2-MN) was carried out over NH 4 F and Pt modified HZSM-5 (SiO 2 /Al 2 O 3 = 83) catalysts in a fixed-bed down-flow reactor using methanol as methylating agent and 1,3,5-trimethylbenzene (1,3,5-TMB) as a solvent. Pt promoted HZSM-5 catalysts showed low concentration of coke-like polycondensed aromatics, NH 4 F modification decreased non-shape-selective acid sites. After Pt and NH 4 F co-modification, both conversion of 2-MN and selectivity to 2,6-DMN were improved. 6%NH 4 F/0.5%Pt/HZSM-5 catalyst exhibited 13.8% of 2-MN conversion with 6.2% of 2,6-DMN yield after 7 h time on stream (TOS), and 2,6-/2,7-DMN ratio of 1.7 after 10 h of TOS.

Improving mine safety technology and training in the U.S.recommendations of the Mine Safety Technology and Training Commission

The key issues studied focused on underground coal mining and included (1) prevention of explosions in sealed areas,(2) better emergency preparedness and re- sponse,(3) improvement of miners' ability to escape,(4) better protection of miners before and after a fire or explosion,(5) improved provision of oxygen,and (6) development and implementation of more robust post-incident communication.The U.S.Congress passed the Mine Improvement and New Emergency Response Act of 2006,which mandated new laws to address the issues.Concurrent with investigations and congressional deliberations, the National Mining Association formed the independent Mine Safety Technology and Training Commission to study the state-of-the-art relative to technology and training that could address the vulnerabilities exposed by the mine disasters.As discussed,the report outlined persistent vulnerabilities linked with significant hazards in underground coal mines, and made recommendations to provide a path for addressing them.Overall the commis- sion report made 75 recommendations in the areas of risk-based design and management, communications technology,emergency response and mine rescue procedures,training for preparedness,and escape and protection strategies.In its deliberations,the commis- sion importantly noted that mine safety in the U.S.needs to follow a new paradigm for en- suring mine safety and developing a culture of prevention that supports safe production at the business core.In the commission's viewpoint,the bottom line in protecting coal miners is not only adopting a culture of prevention but also systematically pursuing mitigation of significant risks.

催化:古老却富有挑战性的石墨烯基材料(英文)

An assessment is offered regarding the progress made, and the remaining challenges, in the field of carbocatalysis. The fundamental principles that govern the preparation and performance of sp2-hybridized carbon materials in heterogeneous catalysis have been known for decades, and the level of understanding of key issues – especially the importance of textural and ion-exchange properties (i.e., surface area, pore size distribution, and proton transfer) – remains quite satisfactory. The opportunities for novel catalytic materials – especially graphene nanosheets and carbon nanotubes– are tremendous, especially when it comes to taking advantage of their structural order, such that electron transfer can be both better understood and controlled to enhance catalytic activity and selectivity.

Al2O3 and CeO2-promoted MgO sorbents for CO2 capture at moderate temperatures

A series of Al2O3 and CeO2 modified MgO sorbents was prepared and studied for CO2 sorption at moderate temperatures. The CO2 sorption capacity of MgO was enhanced with the addition of either Al2O3 or CeO2. Over Al2O3-MgO sorbents, the best capacity of 24.6 mg- CO2/g-sorbent was attained at 100 ℃, which was 61% higher than that of MgO （15.3 mg-CO2/g-sorbent）. The highest capacity of 35.3 mg-CO2/g-sorbent was obtained over the CeO2-MgO sorbents at the optimal temperature of 200 ℃. Combining with the characterization results, we conclude that the promotion effect on CO2 sorption with the addition of Al2O3 and CeO2 can be attributed to the increased surface area with reduced MgO crystallite size. Moreover, the addition of CeO2 increased the basicity of MgO phase, resulting in more increase in the CO2 capacity than Al2O3 promoter. Both the Al2O3-MgO and CeO2- MgO sorbents exhibited better cyclic stability than MgO over the course of fifteen CO2 sorption-desorption cycles. Compared to Al2O3, CeO2 is more effective for promoting the CO2 capacity of MgO. To enhance the CO2 capacity of MgO sorbent, increasing the basicity is more effective than the increase in the surface area.