Instilling an acidic catalyst to a reaction mixture can be beneficial during the acylation of cellulose. Methods described herein can comprise preparing a reaction mixture comprising an acylating agent and cellulose, instilling a catalyst comprising an acid to the reaction mixture at an overall catalyst loading level of about 1% or less by weight of the cellulose, and reacting the cellulose with the acylating agent in the presence of the catalyst, thereby forming an acylated cellulose.