abstracts - Институт катализа им. Г.К. Борескова

PL-6spatially resolved velocity maps for gas flow in various channels, and distributions of flowvelocities for gas flow in porous media, e.g., in granular beds. This has also allowed us toexplore experimentally the differences in the characteristics of gas and liquid flows. Inparticular, experimentally detected distributions of axial molecular displacements in fibertypemicroreactors demonstrate that gas flow can be readily made plug-like even if the reactorstructure is irregular, while for liquids the distribution of velocities is unfavorable and leads toimpractical distributions of contact times. Our MRI studies of the flow and filtration ofgranular solids have primarily addressed the gravity driven transport of solid particles in pipesand through stationary beds comprised of larger solid grains. Such processes are used for heattransport intensification in endo- or exothermic heterogeneous catalytic reactions as well asfor conversion intensification based on the selective adsorption of a product. However, theability to measure velocity distributions of solid particles and to obtain spatially resolveddensity and velocity maps of the solid phase will be of importance for many technologicalprocesses, such as pneumatic transport of granular solids, soot combustion in diesel engines,fluidized catalyst beds, etc.Drying and adsorption. Our MRI studies of drying processes cover a broad range ofmaterials, including porous alumina pellets, textile samples, unmodified or washcoatedmonoliths, etc. These systems were used as models for evaluating parameters characterizingmass transport and exchange processes which in many cases govern the efficiency ofheterogeneous catalytic reactions. At the same time, drying is an important technologicalprocess in itself and often represents one of the stages of, e.g., preparation of catalyst supportextrudates or impregnated supported catalysts. Therefore, a number of experiments on thedrying of monoliths with or without washcoats and active components have been performed.Adsorption studies will be exemplified by the preparation of supported catalysts as well as thestudies of water sorption by composite water sorbents comprising hygroscopic salts dispersedin a porous matrix. The latter system is important for, e.g., heat pumps development andapplications.Imaging of the solid phase and multinuclear imaging. MRI studies are usuallyperformed on liquids or liquid-containing samples, even if the information about the solidstructure is sought. It will be demonstrated that in fact MRI of many rigid solids can beperformed with commercial microimaging instruments. In particular, alumina and other Alcontainingmaterials (glass, ceramics) are relatively easy to image. This essentially opens up awindow to an entirely new dimension for MRI applications in chemical engineering andcatalysis. The most obvious use is for non-destructive structural studies of, e.g., catalyst beds.19