This invention relates to a process for converting a hydrocarbon feedstock, comprising the steps of (A) feeding the feedstock to a reactor or adsorption unit; (B) contacting the feedstock in the reactor or adsorption unit with a solid particulate material useful for converting the feedstock under conversion conditions; (C) withdrawing converted feedstock from the reactor; and (D) removing, under the conversion conditions for a fractional time of step (B), at least a portion of the solid particulate material while the feedstock is being fed to the reactor or adsorption unit, wherein the portion is more than 0.1 wt. % of the solid particulate material in the reactor or adsorption unit and wherein the fractional time is less than 95% of the time of step (B).