Manufacturers and suppliers of catalysts and adsorbent materials. Catalysts interact with chemical substances and induce reaction of these substances, without themselves being converted. They are commonly divided into heterogeneous catalysts (solids that are not soluble in the reaction media), and homogeneous catalysts (which are miscible or soluble in the reaction media). Adsorbents are solid materials that interact with chemical substances in a gas or liquid phase, but do not chemically convert these substances. They are typically used in separation processes, for example to remove impurities. Catalysts and adsorbents are closely related because they share similar surface properties, and are often manufactured by the same companies.