Processes and systems for using silica particles in fluid bed reactor

A reactor system for preparing acrylonitrile product, comprising:

• a fluid bed comprising a catalyst composition comprising a catalyst and an inert additive composition comprising from 0.5 wt % to 30 wt % of silica particles, based on the total weight of the catalyst composition;
• and
• one or more gas inlet feeds for passing one or more reactants upwardly through the fluid bed to form an acrylonitrile product,
• wherein the difference between the density of the silica particles and the catalyst particles ranges from 0.5% to 75%,
• wherein the silica particles reduce erosion of the reactor by greater than 10% compared to a similar process conducted without from 0.5 wt % to 30 wt % silica particles.