Today many chemical reactors use fluidized beds. For example, the commercial synthesis of acrylonitrile, phthalic anhydride, aniline, maleic anhydride, and a portion of the polymerization of ethylene (to polyethylene) and propylene (to polypropylene) are all done in fluid bed reactors. There are noncatalytic processes, such as ore roasting, coking, combustion of coal and other solid fuels, as well as purely physical processes such as drying and conveying of fine particle products like flour, rice, and cement, which use the principles developed for the fine-particle fluidized bed.