Nanoscale MgO, prepared by an aerogel method (AP-MgO), has been found to be a good destructive adsorbent for dehydrochlorination of 1-chlorobutane. MgO is converted to MgCl2 during reaction, but conversion continues because MgCl2 itself is a good catalyst for dehydrochlorination. Pelletization will likely be required in industrial use of AP-MgO to ensure lower pressure drop. Pelletization, however, can lead to internal diffusion limitations. In addition, the phase transformation of MgO to MgCl2 inside the pellets leads to physical changes that may limit the reaction rate. This study reports the changes in AP-MgO physical properties upon pelletization and reaction with 1-chlorobutane. Pore diffusion limitations are noted for all pellets. The phase transformation of MgO to MgCl2 plays an important role in the process, as the physical characteristics substantially change with this transformation. A layer Of MgCl2 forms on top of MgO, rendering much of the starting pellet inaccessible to reactants. (C) 2004 American Institute of Chemical Engineers.