Functional MRI and NMR spectroscopy of an operating gas–liquid–solid catalytic reactor Igor V. Koptyug a, T , Anna A. Lysova a , Alexander V. Kulikov b , Valery A. Kirillov b , Valentin N. Parmon b , Renad Z. Sagdeev a a International Tomography Center, Novosibirsk 630090, Russia b Boreskov Institute of Catalysis, Novosibirsk 630090, Russia Abstract A dynamic in situ study of a-methylstyrene catalytic hydrogenation on a single catalyst pellet or in a granular bed is performed using 1 H MRI and spatially resolved 1 H NMR spectroscopy. Owing to reaction exothermicity, a reciprocating motion of the liquid front within the pellet accompanied by pellet temperature oscillations has been observed. Spatially resolved information on the reactant to product conversion within the catalyst bed has been obtained for a steady-state regime. Two-dimensional 27 Al NMR images of alumina catalyst supports and other alumina-containing materials have been detected using moderate magnetic field gradients (80 G/cm) and a two-pulse spin-echo sequence. Temperature dependence of signal intensity and 27 Al T 1 time of alumina are considered as possible temperature sensors for NMR thermometry applications. D 2005 Elsevier Inc. All rights reserved. Keywords: Heterogeneous catalysis; Hydrogenation; Gas–liquid–solid reaction; a-Methylstyrene; Alumina; Nuclear magnetic resonance imaging; 27 Al MRI; NMR thermometry 1. Introduction To adequately respond to the challenges of the new century, chemical and process engineering must develop innovative industrial processes and enhance the efficiency and safety of large-scale multiphase reactors. This requires a detailed knowledge of the chemical and transport processes within an operating reactor. The mutual influence of these processes often leads to an unconventional behavior, e.g., concentration oscillations, traveling waves, hot spots for- mation and reactor runaway. Therefore, in many cases dynamic studies on an operating reactor are required to obtain relevant information. In this respect, MRI represents a unique experimental toolkit which holds significant promise for characterizing various aspects of reactor behavior. However, the MRI studies performed in the field of chemical engineering and catalysis are mostly concerned with the internal structure and mass transport under simplified, nonreactive conditions [1– 4]. Only a few room temperature studies of two-phase (liquid–solid) reactors have been reported to date [5,6]. At the same time, the behavior of the three-phase (gas–liquid–solid) reactors operating at elevated temperatures can be fundamentally different owing to their inherent tendency to the develop- ment of critical phenomena due to the nonlinear coupling of transport and reaction. Application of MRI to study such processes remained a challenge until very recently [7,8]. Reactors with cocurrent downward multiphase flow are widely employed in petrochemical synthesis and oil refining processes, which makes the dynamic studies of their operation extremely important. 2. Experimental Alumina pellets or beads (g-Al 2 O 3 , specific surface area 206 m 2 /g, pore volume 0.65 cm 3 /g) were used in the experiments. Supported catalysts (g-Al 2 O 3 +1% Pd+0.1% Mn) were prepared by impregnation as described else- where [8]. a-Methylstyrene (AMS), cumene and molecular hydrogen were used as received. Prior to catalytic experi- ments, catalyst was activated in a stream of an air/ hydrogen mixture for half an hour and then placed in the reaction cell positioned inside the NMR probe. During 0730-725X/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.mri.2004.11.022 T Corresponding author. Tel.: +7 3832 333561; fax: +7 3832 331399. E-mail address: koptyug@tomo.nsc.ru (I.V. Koptyug). Magnetic Resonance Imaging 23 (2005) 221 – 225