... the catalyst and prolong the operating cycle of the system. As the impurities present in the materials are different, the user can select the product by their sizes ... %,and every more 5% constitutes a grade, but 12 sizes by reference to the diameter, such as Φ3 ,Φ6 ,Φ8 ,Φ10 ,Φ13 ... , Φ16 ,Φ20 ,Φ25 ,Φ30 ,Φ38 ,Φ50, Φ75. The products in other grade and sizes can be designed and manufactured if to ...