Crystalline silica mol. sieve prodn. by hydrothermal treatment - using fly ash from silicon or ferrosilicon mfr. as amorphous silica

摘要

Prodn. of crystalline SiO2 mol. sieves (I) involves hydrothermal treatment of a reaction mixt. with a pH of min. 10 (min. 11, esp. 12-13), contg. amorphous SiO2 (II), water an alkyalonium cpd. (III) of the formula R4X(+) (in which R is H or 2-6C alkyl; X is N or P) and opt. an alkali metal hydroxide or NH4OH at temps. above 100 (100-200) deg. C and elevated pressure, followed by isolation and calcination of the prim. crystalline prod. The novel feature is that fly ash formed in the prodn. of Si and/or ferrosilicon alloys is used as (II). The process is much quicker than usual and uses a less costly starting material.