In Situ Surface Analysis in Selective Oxidation Catalysis: n-Butane Conversion Over VPP

In situ analysis of the surface of a working selective oxidation catalyst is an essential yet rarely conducted experiment in attempts to derive structure–function relationships. The case study of n-butane oxidation over vanadyl pyrophosphate (VPP) is used to develop a general working hypothesis and to illustrate that the molecular properties of the substrate sets boundary conditions on the surface chemical properties of the catalyst. Experiments using in situ X-ray photoelectron spectroscopy (XPS) and in situ low-energy X-ray absorption spectroscopy are used to derive compositional, electronic, and geometric structural information of the surface of the working VPP. These data allow the conclusion that a surface phase different from VPP must be present covering at least part of the active material. The recent data together with literature observations are used to derive a scenario explaining the function of VPP as a unique catalytic system.     

Practical aspects of the ventilation of high-speed developing tunnels in hot working environments

The excavation of ramps and tunnels often requires high-speed development with [or without] the use of high-energy mining equipment such as loaders, dump trucks, TBMs and roadheaders. This highspeed development creates a challenge in terms of providing a safe and productive working environment. For example, heat from continuously exposed surrounding rock, heat from broken rock, heat generated by mining equipment, potential inflows of hot ground water, pollution from associated diesel equipment, and the distance of the advancing face from fresh through-ventilation all have to be taken into account when designing ventilation systems for high-speed ramp and tunnel developments. This paper discusses methods of achieving acceptable environments at the face and along the length of the tunnel. The methodology has been successfully implemented in the development of long [up to 20 km] TBM drives in the Lesotho Highlands Project and in mining projects in hot rock using drill-and-blast methods as well as in mechanised methods using continuous miners and roadheaders. The determination of heat loads includes calculation of the heat flow within the surrounding rock, evaluation of the operating cycle of the equipment and the contribution to the overall heat load of the broken rock as it travels out of the tunnel. The determination of heat loads from surrounding rock in new tunnels required a modification of the algorithms generally used for established excavations. The paper also examines the use of, for example, mobile duct and fan systems to ensure that fresh air is delivered to the specific areas where workers are located.     

同步辐射近常压光电子能谱及其应用

介绍了同步辐射近常压光电子能谱的基本概念、发展历程以及该技术的装置和原理。列举了几个近常压光电子能谱的应用领域。该技术填补了超高真空和真实条件下压强上的空白,在原位研究表面化学变化、催化反应,腐蚀以及电化学过程上有着很大的优势。