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Rates of hydration of isobutene were measured with Amberlyst-15 catalyst particles in a differential, liquid-full recycle reactor operating at atmospheric pressure and 303 to 333 K. Catalysts pretreated in two different ways were studied. Liquid-to-particle mass transfer had a small but measurable effect on the rate. Intraparticle diffusion was more significant, as indicated by effectiveness factors from 0.26 for the larger catalyst particles (dp = 1.04 x m) at 333 K to 0.84 for the smaller particles (dp = 0.45 x m) at 303 K. The intrinsic rate was first-order in isobutene concentration with an activation energy of 67 kJ/mol. The intraparticle diffusion resistance is due to the macropores surrounding the very small gel-type microparticles of which the particles were composed. Some data were obtained for reaction rates in trickle-bed operation. Global rates were somewhat lower in the trickle-bed operation than in the liquid-full runs. Using the previously determined intrinsic kinetics and effectiveness factors, the liquid-to-particle mass transfer coefficients could be approximated for the trickle-bed operation.

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KEY WORDSMoS 2 structure; high resolution electron microscopy; image simulation; moiré patterns. ABSTRACTThe contrast observed in the 700018 HREM images of MoS 2 are interpreted with a model based on rotational moiré patterns. Computer-simulated images show that rotations of two supercells by angles of 3, 5, 8, and 16 degrees around their centers reproduce the contrast observed in the experimental images. The calculations suggest that these rotations occur between the sulphur layers of the MoS 2 structure.

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